By Dominic Crea
Clinton Twp, Michigan 48036
This article is being written in response to a recent paper by Amory Lovins —“Twenty Hydrogen Myths”—and wishes to identify what this author believes are a series of errors and misleading statements contained in that document. Doubtless, this paper will find itself questioned in turn; this is encouraged since an active and healthy debate amongst concerned scientists, engineers and the general public will ultimately clarify rather than confuse the issues surrounding the Hydrogen Economy.
This analysis will begin by considering some of the “introductory facts” that are used in the early part of Mr. Lovins’ paper. Many of these statements, most notably the premise that, “A hydrogen fuel-cell car can therefore convert hydrogen energy into motion about 2–3 times as efficiently as a normal car converts gasoline energy into motion”, need to be examined in detail since they lead to invalid conclusions later in his paper. That having been said, let us continue:
1) Page 5, bullet #1: “…but unlike electricity it [hydrogen] can be stored in large amounts...”
This is a curious remark since the energy contained in hydrogen is electrical in origin.
All chemical reactions—from the explosion of methanol and air in the cylinder of an automobile engine to the movement of electrons in an external circuit of a hydrogen/ oxygen fuel cell-powered vehicle—operate via changes in the electric potential of that system. Therefore, electricity can be (and is) stored. To be sure, hydrogen can effectively store large amounts of electricity when coupled to a fuel cell generator, but even greater amounts (volume energy density) can be stored in the form of various alcohol and methane-fueled heat engine/generator sets of which the hybrid car and combined-cycle generator are but a few examples. While Mr. Lovins’ does acknowledge the superior volume-energy density of methane and alcohol, he later asserts (bullet #6) that the fuel cell’s increased efficiency will more than offset this advantage. This is a false premise and will be explained in a moment.
Many proponents of the Hydrogen Economy will make use of a variant of this statement—the “electricity cannot be stored” argument—but this is really quite misleading, more so when one considers that electricity is, in fact, stored on a regular basis (hydroelectric, compressed air, pumped water storage and heat of fusion storage in solar power tower facilities). Indeed, a most enticing form of electric storage is by means of batteries in electric cars. Furthermore, as we shall see later, battery electric vehicles (BEVs) store excess electricity with far less loss compared to hydrogen storage methods. This in turn translates to a significant reduction in the number of power stations required (in the case of centralized generation) or fewer PV panels and wind generators in the case of distributed, renewably-generated electricity (half as many or less).
Incidentally, now might be a good time to mention the fact that many of the comparisons made in Mr. Lovins’ paper were between “normal cars” that, while admittedly poor (e.g., inefficient, non-hybrid powertrains), are not representative of the current state-of-the-art in vehicular propulsion. The problem with his approach is that it tends only to highlight the most optimistic predictions about hydrogen (and fuel cells) while playing down its many shortcomings. Allow me to expand on this point: Fuel cell vehicles (FCVs) and the hydrogen economy are examples of technologies, while technically possible, have yet to prove themselves practically or economically; there are still a number of very serious hurdles for them to overcome. On the other hand, hybrid electric vehicles ( HEVs) and BEVs ( battery electric vehicles) represent technology that is available today; they are affordable, practical and above all else, proven to work—people actually drive these vehicles on a daily basis. I will speak about this in more detail later.
2) Page 5, bullet #1: “Like electricity, hydrogen is an extremely high-quality form of energy, and can be so readily converted to electricity and back again…”
This is an interesting statement. Using Mr. Lovins’ numbers of 45% roundtrip efficiency (Myth #3) in the conversion of electricity to hydrogen and back again, we are forced to admit a loss of more than HALF of the original electricity that we started with (some estimates put this loss considerably higher). Bearing this in mind, we are confronted with a very sobering fact: Of the number of generators needed to supply energy to this conversion process, less than half as many would be necessary if we never made the conversion to hydrogen in the first place! In a renewable context that is driven by solar and wind, this will effectively amount to sacrificing more than half of the photovoltaic panels or wind generators just to overcome the losses inherent in such a circuitous conversion scheme.
To be sure, there are good and necessary reasons for accepting some conversion losses (I’ll show later how to dramatically reduce these losses) and energy storage is just one of them, but it does not support the premise of equating hydrogen to electricity in terms of “quality”. Trying to compare a process that is 45% efficient to one that is 100% efficient is like comparing two test scores of 45% and 100%: the former, unlike the latter, can hardly be considered as “extremely high-quality”.
3) Page 5, bullet #5: “Hydrogen is thus most advantageous where lightness is worth more than compactness, as is often true for mobility fuels.”
I would tend to agree with Mr. Lovins in the case of the most obvious theoretical example—aviation—more so when you consider the safety of using hydrogen as opposed to kerosene. But even this case has only demonstrated a 10%-15% savings in fuel—not insignificant but far less than one would be led to believe given hydrogen’s 3-to-1 weight-energy density advantage over virtually every other hydrocarbon fuel. While Amory does admit that, “Even when hydrogen is compressed to 170 times atmospheric pressure (170 bar), it contains only 6% as much energy as the same volume of gasoline,” it is unfathomable why he would then assert that hydrogen’s, “lightness is worth more than compactness, as is often true for mobility fuels.”
In fact, it is the volume energy density (the amount of energy contained in a particular volume of that fuel) that is the decisive factor in automotive design and hydrogen fares very poorly in this regard. I know of no other instance, except space travel, where the weight of a hydrocarbon or alcohol fuel was considered a liability relative to hydrogen. Certainly, it has never represented a problem in domestic vehicular systems.
3) Page 5, bullet #6, 1st paragraph:
“Fuel cells (explained further in Myth #6) are not subject to the same thermodynamic limits as fuel-driven engines, because they’re electrochemical devices, not heat engines.
A hydrogen fuel-cell car can therefore convert hydrogen energy into motion about 2-3 times more efficiently as a normal car converts gasoline energy into motion….a good fuel –cell system is about 50-70% efficient, hydrogen-to-electricity, while a typical car engine’s efficiency from gasoline to output shaft averages only about 15-17%”
This premise—mentioned at the beginning of the paper—is perhaps the most contentious of all; it forms the basis of many of the arguments that are to follow in Mr. Lovins’ paper. For that reason, it must be evaluated carefully. Let’s start with the claim that “Fuel cells are not subject to the same thermodynamic limits as fuel-driven engines” which then leads to the conclusion that, “A hydrogen fuel-cell car can therefore, convert hydrogen energy into motion about 2-3 times more efficiently as a normal car…”.
This is false. Fuel cells and internal combustion engines are subject to exactly the same thermodynamic limits that are dictated by the “available energy” which in turn sets an upper limit to both systems of about 83% given the kind of fuel and lower operating temperature. This is a common mistake1 and probably originated from the confusion between the practical limitations of materials in the heat engine vs. the upper theoretical temperature; they are not the same.
The next question is that of fuel cell “efficiency”. In actual automotive applications, 40-50% 2 is considered the normal operating efficiency before including various parasitic losses. Furthermore, Mr. Lovins makes an error typical in fuel cell circles—comparing electrical output to shaft output (they are very different). He then goes on to make the comparison to a “typical car engine” of only “15-17%” and arrives at the “2-3 times” more efficient premise; this is an invalid comparison since it overlooks the fact that electricity is not the same as mechanical energy, which is what actually propels a vehicle. It is especially odd since he later (myth#3) acknowledges only a “1.5 times higher” efficiency advantage of a FCV over an HEV—quite a bit lower! Why he avoids doing this from the beginning, and even more puzzling, why he chooses not to use this fact later in his analysis is somewhat of a mystery since HEVs are currently on the road. Any comparisons made and conclusions drawn are only valid relative to the most efficient technology available today; we might just as well compare an FCV to a “Model T” or “Stanley Steamer”.
Let us return for a moment to the question of an FCV’s efficiency: we need to be very careful how this is defined. Including the losses in the air compressor, inverter, motor, etc., we find that the actual efficiency is somewhat lower—31-39% as measured in some labs—and while this number is the subject of much discussion (and, understandably, disagreement), it becomes clear that it is no where near the “2-3 times” premise espoused by Mr. Lovins’, especially when compared to an ordinary HEV. In fact, if we go a little further and make comparisons to a high-compression natural gas or alcohol HEV, whose shaft efficiency is just over 40%, the distinction between the two vehicles begins to blur. Many engineers are aware of this fact and are beginning to agree that the reported differences in efficiency are probably not as great3 as has been assumed.
To provide an example of how easily we can jump from one conclusion to another, consider two representative real world vehicles: The Honda FCX (fuel cell) and the Toyota ES3 diesel hybrid (Eco-Spirit 3), both of which hold four passengers. The Honda FCX was rated at 50 mpg; the Toyota ES3 at 104 mpg. Wait a minute! Haven’t we been told that fuel cell vehicles are “2 to 3 times more efficient”? Things seemed to have reversed—how can a hybrid get more than twice the mileage of an FCV? Well, the answer is in the details and who is doing the reporting. It is highly unlikely that a hybrid could be more than twice as efficient as a fuel cell car; the comparison is somewhat tainted. For one thing, the Toyota uses diesel fuel (12% greater energy per unit volume). For another, the Honda FCX is a heavier and offers more wind resistance. An attempt was made to deliberately avoid comparing “apples to apples” in an effort to demonstrate how easily (and incorrectly) one can distort the facts and arrive at contradictory conclusions; this is why we need to be very careful when assessing efficiency and the claims thereupon made.
Still, the stark reality is that an existing hybrid car seating 4 passengers gets twice the mileage of an existing fuel cell car holding the same number of people—this is a fact, not a prediction. In all fairness, when the dust finally settles, fuel cell and hybrids cars will probably come out in a tie; this is a fair (and probably safer) assumption upon which to base all future arguments.
Having made this point, we move on to the very next statement in the same bullet where Mr. Lovins again uses the “2-3 times” premise to make the following conclusion:
“This means you can drive several times as far on a gallon-equivalent (in energy content) of hydrogen in a fuel-cell car as on a gallon of gasoline in an engine-driven car. Conversely, hydrogen costing several times as much as gasoline per unit of energy contained can thus cost the same per mile driven.”
This would be true if we used the “2-3 times” greater efficiency premise, but Mr. Lovins later acknowledges the fact that hybrid vehicles will reduce this advantage to only “1.5 times” better efficiency; therefore his conclusion does not follow; i.e., “…hydrogen costing several times as much as gasoline…can cost the same per mile driven.” On the contrary, it would now appear that hydrogen will cost almost twice as much as gasoline per mile driven using Mr. Lovins’ own numbers (even more if we agree that FCVs and HEVs will probably come out even in terms of efficiency). Again, making such a conclusion based on non-hybrid inefficient engine technology is no comparison at all; he is using an inappropriate premise which leads to a false conclusion.
The reader is advised to remember that many of the estimates for the cost of hydrogen are based on the assumption that it will be produced from natural gas—hardly the basis for a renewable energy program. Mr. Lovins also assumes that we will eventually wean ourselves off of this feedstock long before depletion becomes an issue. I have very strong misgivings about such an assumption and am in direct opposition to such a plan for many reasons, not the least of which is the fact that it will trade foreign dependency on oil for foreign dependency on natural gas. I will speak on this matter in greater detail in my concluding remarks at the end of this paper.
In this second installment, I’ll begin to touch on some of the “myths” in Amory Lovin’s paper:
Myth #1, page 8, 3rd paragraph:
“Pipelines may be cheaper, easier to site, and more secure than aboveground high-voltage electric transmission lines.”
While there are many problems with this statement and the section that contains it, I am particularly curious about the use of the word “secure”. The sentence suggests that vulnerability exists in our current electric grid that may not be the case with hydrogen. Interestingly, Amory comments on the susceptibility of pipelines in general in another article (page 6 of Amory Lovins article “Energy Security Facts: Details and Documentation”, April, 2003.) and discusses the possibility of these pipelines being a target for would-be terrorists; in fact, he lists several incidents of sabotage in the same article. Why Amory would think that a hydrogen pipeline is more secure—especially after listing the weaknesses and reported acts of malice against such pipelines in Alaska—is baffling; he ends up refuting his own claim.
I would only like to add that being more “secure” is a matter of opinion: putting an incendiary shell through a 1,000 psi hydrogen pipeline is not very reassuring; the same projectile going through a high-voltage transmission line is far less devastating in its effect. If anyone has ever seen a natural gas fire from the end of pipeline distribution node (I have), I think they will agree that it is quite a spectacle. Consider this: severing a transmission line, while certainly disruptive, essentially stops the flow of energy; a ruptured pipeline on the other hand, ignited by an explosive or incendiary shell, will dump an enormous amount of compressed hydrogen into the atmosphere, whereupon, it will ignite and burn with a fury. Furthermore, consider the operations involved in repairing this problem: First, the gas line must be shut down allowing the compressed hydrogen to burn itself off (it will do this rather quickly). From here, the line must be purged of any remaining hydrogen; the damaged section cut away and a new section welded back in place; now the line must be purged of air and then brought back up to pressure with hydrogen. This is a crippling situation that warrants consideration as to what we mean by “secure”.
On the other hand, repairs made to electric transmission lines are routine and are often done while the line is “hot” using helicopters that support workers who make repairs while actually touching lines at potentials of several hundred thousand volts. This is dangerous work to be sure, but these highly skilled workers make repairs in many cases with little, if any, interruption of service to their customers.
Which of the two targets—a hydrogen pipeline or an electric transmission line—would provide a more inviting target to a would-be terrorist? Which do you think would disrupt a nation’s energy supply more completely?
Myth #2, page 9, 2nd paragraph:
“Hydrogen mixtures in air are hard to explode, requiring a constrained volume of elongated shape.”
I honestly don’t understand what Mr. Lovins means by “hard to explode”; hydrogen is very easy to explode when just the least bit constrained. As a chemistry and physics instructor, I can tell you stories about all kinds of explosions that took place in my lab with hydrogen—without terrible difficulty I should add! Some “events” were very insidious as invisible flames flashed back suddenly into the hydrogen generator causing a very well defined explosion along with some messy clean up and pretty frightened students (fortunately, “experience” has taught me to use plastic containers and rubber hoses). As far as requiring an “elongated shape”, I regularly demonstrate the explosive limits of fuel gases—including hydrogen—in a very squat paint can; the experiment illustrates dramatically the explosive force of hydrogen (not to mention the fact that it has the highest flame velocity of any fuel gas). Interestingly, I have never once experienced an alcohol burner explosion (although, admittedly, I have burned myself on a number of occasions!)
Let us be very clear on this point: Hydrogen mixed with air in an enclosed space (like a garage for instance) is very easy to explode. If you’d like a scenario that is a little more convincing, imagine a hydrogen car leaking into a closed garage. Now further imagine that someone comes from inside the house into the garage with a lighted cigarette. If you’re a non-smoker great, but what if you hit the garage door opener button (the closing contacts of the switch create just enough of a spark to do the deed nicely and at a higher elevation where gasoline fumes don’t hang out). And what about all the explosions (this happened to a friend of mine) that occur every year when people are recharging their car batteries? Fortunately, only very small amounts of hydrogen are produced but it’s still enough to destroy the battery and spray a person with acid.
The point is this: Hydrogen can and does explode; I can set off hydrogen/air explosions with the greatest of ease (hydrogen is more susceptible to a static discharge than any other fuel). I can make all kinds of sparks from anything like recharging my dead battery in the garage to dropping a work light on the floor or even combing my hair. True, gasoline and, to a far lesser extent, alcohol are susceptible to these dangers, but these fuels cling to the ground and flow out of openings like the bottom of the garage door. Moreover, leaks in liquid fuel tanks are generally very easy to detect by your nose and eyes; hydrogen would require an odorant (this actually may be easier said than done since most odorants contain sulfur compounds that will “poison” PEM fuel cell) and would still lack the visual clue.
In short, given the choice of being in a garage with any leaking fuel…I’d rather not have to make the choice! Let’s not understate the danger of hydrogen; it has an insidious way of doing just what you think it shouldn’t. Doesn’t it make a lot more sense to assume that it can explode rather than play down the hazard? I really believe Mr. Lovins should have passed on this one and simply admitted that any fuel—gasoline, methane, alcohol and even hydrogen—is simply too dangerous to be treated as though it won’t explode and have left it at that.
Myth #3, page 11, 2nd paragraph: “Using Japanese round numbers from Toyota, 88% of oil at the wellhead ends up as gasoline in your tank, and then 16% of that gasoline energy reaches the wheels of your typical modern car, so the well-to-wheels efficiency is 14%. A gasoline-fueled hybrid-electric car like the 2002 Toyota Prius nearly doubles the gasoline-to-wheels efficiency from 16% to 30% and the overall well-to-wheels efficiency from 14% to 26%. But locally reforming natural gas can deliver 70% of the gas’s wellhead energy into the car’s compressed-hydrogen tank. That “meager” conversion efficiency is then more than offset by an advanced fuel-cell drive system’s superior 60% efficiency in converting that hydrogen energy into traction, for an overall well-to wheels efficiency of 42%. That’s three times higher than the normal gasoline-engine car’s, or 1.5 times higher than the gasoline-hybrid-electric car’s. This helps explain why most automakers see today’s gasoline-hybrid cars as a stepping-stone to their ultimate goal — direct-hydrogen fuel-cell cars."
This is why the original premise of “2-3 times higher efficiency” was questioned earlier; it forms the basis of all ensuing conclusions. If we agree that a high-compression HEV will achieve the same overall efficiency as an FCV, then everything turns around: reforming natural gas into hydrogen to be used with an FCV wastes about 20% more fuel than would be the case of running the methane directly into a high compression HEV. The real point of this observation is why Mr. Lovins repeatedly insists on making the comparison between an FCV and a non-hybrid (conventional engine power train) in his analysis; it is logically irrelevant for the reasons stated earlier; i.e., any comparisons must be made relative to the most efficient existing power train—high-compression HEVs.—since this will be the competing force that drives the decision as to what system we eventually adopt (HEV vs. FCV).
He goes on to explain “why most automakers see today’s gasoline-hybrid car’s as a stepping-stone to their ultimate goal—direct hydrogen fuel-cell cars.” I have talked with several auto manufactures; they have given me very different and very intelligent reasons why they’re interested in hybrids: hybrid technology can operate on a variety of fuels; the current liquid and gaseous fuel infrastructure is perfectly compatible with these cars and finally, they are the test-bed for improvements in battery technology should such developments occur (I believe this is inevitable). If anything, I believe it is safe to say that hybrid technology will usher in an era of “Plug-in Hybrid Electric Vehicles” (PHEVs: cars that can go some reasonable distance on electricity alone). This will require no technical breakthrough; the Toyota Prius is an example of one step in this inevitable evolutionary chain.
Pursuing hybrid technology is a sensible and secure plan; it involves virtually no change to our present infrastructure and allows for the possibility of a completely renewably-based system of fuels. Redundancy is the key word here and the ability to use electricity, alcohols, propane, methane, butane, gasoline and even hydrogen makes this choice far less problematic than the fuel-cell powered car.
Moving on to the middle paragraph on the same page:
“In competitive electricity markets, it may even make good economic sense to use hydrogen as an electricity storage medium. True, the overall round-trip efficiency of using electricity to split water, making hydrogen, storing it, and then converting it back into electricity in a fuel cell is relatively low at about 45% (after 25% electrolyzer losses and 40% fuel-cell losses) plus any byproduct heat recaptured from both units for space-conditioning or water heating. But this can still be worthwhile because it uses power from an efficient base load plant (perhaps even a combined cycle plant converting 50–60% of its fuel to electricity) to displace a very inefficient peaking power plant (a simple-cycle gas turbine or engine-generator, often only 15–20% efficient). This peak-shaving value is reflected in the marketplace. When the cost of peak power for the top 50–150 hours a year is $600–900/MWh, typically 30–40 times the cost of base load power (~$20/MWh), the economics of storage become quite interesting. Distributed generation provides not only energy and peak capacity, but also ancillary services and deferral of grid upgrades. Hydrogen storage can also save power-plant fuel by permitting more flexible operation of the utility system with fuller utilization of intermittent sources like wind. Once all the distributed benefits are accounted for, using hydrogen for peak storage may be worthwhile, particularly in cities with transmission constraints (such as Los Angeles, San Francisco, Chicago, New York City, and Long Island). Such applications may be able to justify capital costs upwards of $4,000/kW.”
As Mr. Lovins rightfully points out, the premium on energy storage can sometimes justify it’s greater cost and lower efficiency, but there are other ways to achieve this goal—ways that are far more efficient and less costly: Why not store that extra electric capacity in the ultimate form in which it’s needed, thus reducing or entirely eliminating the need for peak shaving generators? For example, refrigerators and air conditioners could easily incorporate heat of fusion materials for storing cold (ice is amazingly effective and essentially free). To provide actual numbers, consider the following: using excess electricity (day or night), we can freeze a cube of water 3 feet on a side (about the size of a household dishwasher) using very inexpensive refrigeration technology. This amount of ice (about 2,000 lbs.) will store the equivalent of 288,000 BTUs or about 12 hours of air conditioning for the average house in the full heat of a summer day (increasing this cube to 4 feet on a side will more than double the storage capacity); it will displace more than ½ of all the electricity used for that same house on that particular summer day (when demand for electricity is greatest). To accomplish this same storage in the form of compressed hydrogen (100 atmospheres) will require a cube that is 2 ½ feet on a side—virtually no difference in size from the block of ice but absurdly more expensive. In addition, you would need to absorb the cost of the fuel cell, electrolyzer, compressor and a dozen or more other components—all of this compared to a simple cube of water at normal air pressure with absolutely no danger other than the slight chance of a wet basement in the event of a leak. Add to this the fact that the water and its container will probably never wear out in your lifetime and you have a pretty convincing system of cold storage. And who is to say that we can’t store heat in this same container of water in the winter?
This next possibility is actually a variation of one of Mr. Lovins’ more brilliant ideas and due credit should be given to him: How about storing excess daytime electricity directly in an electric or hybrid car parked at work or a shopping mall (Wall mart actually provided free charging to electric car owners in California) and tapping off some of that energy (say, no more than 10%) to buffer daytime variations in electric demand? The power companies could offer an incentive plan to BEV and HEV owners—perhaps a reduction in electric charging rates or even an “interruptible” service plan (as is done currently with air conditioning service where the rates are about half of normal service). There are many possibilities and it could be a “win/win” situation; it could even provide an impetus to buy an HEV, PHEV or BEV.
More importantly, consider how this would play out compared to an FCV using the converted “electricity-to-hydrogen” scheme: “25%” would be lost in the electric-to-hydrogen conversion alone, coupled with the overall efficiency of an FCV of about 35% (you need to pump that hydrogen into the storage tank)—you’ll end up with about 28% of the energy contained in the original electricity. Compare this to dumping that same electricity directly into a BEV or HEV and you’re looking at about 65%, or more than twice the energy efficiency of an FCV—not to mention the fact that it’s embarrassingly cheaper and doesn’t require an electrolysis or reforming unit; it eliminates the need for hydrogen compressor pumps and the hoses that must be coupled to the fuel tank of the FCV (sealing a hydrogen hose to the tank of an FCV is far more problematic than using electric recharging “paddles”).
We can extend this technique to include the home as well: PV panels “intertied” to the grid could—in fact they already do—act as “distributed generators” helping to level the changing loads that occur throughout the day when the demand for power is greatest. An arrangement might even be made to credit this daytime power for nighttime charging of an electric vehicle whose charging characteristics represent a very smooth, non-varying load; the car could even act as a home emergency reserve of electricity (see the addendum below) in the event of a power blackout . The “Plug-in hybrid electric vehicle” (PHEV) would be even better since it could produce power indefinitely—remember the natural gas line and the ability of a hybrid to operate on all kinds of fuels?.
There really appears to be no sound reason why these alternatives could not do the job far cheaper and more practically than a hydrogen fuel cell system. Mr. Lovins states that even $4,000 per kilowatt might be justified for these fuel cell peak shaving devices; a PHEV with the ability to absorb and deliver power to the grid will run only about 1/10 this price and provide transportation as well.
The point is that the current electric grid, bolstered by renewable energy sources and vastly cheaper storage techniques along with the electric and hybrid car, offer a multitude of far simpler (and potentially more enticing) solutions than those claimed by hydrogen storage techniques. In short, a hydrogen fuel cell peaking generator is unnecessary; use the money to buy PVs and wind generators instead.
Addendum: On Friday, August 14th, 2003, one of the largest, If not the largest, power blackouts hit our country. While the world around us ground to a halt, small pockets of electricity were still being produced, albeit with disturbing levels of noise, by home generator units. My neighbor tapped into my own emergency generator to power his well pump and refrigerator (remember that little discussion about storing cold?), and over the annoying growl of the generator, we began to talk about how disruptive a loss of power was. Suddenly my neighbor made the kind of observation that represented, in a nutshell, the dilemma most Americans face when contemplating the purchase of an emergency standby generator: “I really should buy a generator,” he said, “but it seems that it would pretty much remain idle most of the time—how often do we get power outages anyway?”
This simple observation, so true indeed, brought home the importance and benefit of the PHEV (a hybrid vehicle that includes a substantial battery pack for extended runs on pure electricity alone) that I mentioned earlier in this installment: a plug-in hybrid vehicle could easily double as a home emergency generator, camping generator or even a contractor/domestic portable power source; it would be as mobile as the car itself and would never require lifting or protecting from theft; it would be immune to the weather and never suffer from the malfunctions that occur when equipment remains idle for many years; it’s fuel would never go stale. Keep in mind that such an arrangement has the advantage of operating the engine in the most efficient part of the power curve and electricity would only be drawn as needed. Contrast this with a noisy, polluting (small engines produce tens, if not hundreds of times more pollution than a hybrid vehicle) and inefficient small-engine generator (even when supplying no current, the engine consumes about 50% of its full-power fuel consumption). To give the readers a feel for what I’m talking about, let me illustrate with some real numbers:
A true hybrid would normally carry a minimum of 10 kilowatt-hours of electricity within the NiMH battery pack; this is enough to supply a typical home with about 10 hours of electricity and more like 24-48 hours for a judicious rate of consumption. Unlike the small-engine counterpart, this supply of electric energy would only be drawn as needed, thus accounting for the greatly enhanced storage time (normal generators, even when not supplying power directly will consume about 1/2 gallon per hour or 12 gallons per day—not to mention that unnerving noise!). The hybrid car/electric generator would be completely quiet while operating on batteries; it would be very efficient (typically about one gallon of fuel per day as opposed to 12-15 gallons for the small-engine generator), and its modest 10 gallon fuel tank could conceivably power a house for up to 10 or 20 days—all of this as a bonus for simply making the transition to a true hybrid car! Even when the batteries were running low, the engine would come on automatically every day or so and charge up the batteries in one or two hours of very quiet and clean operation (a 15 kW engine would provide for 80% of full charge in less than an hour).
This same car could even tap into the natural gas line of a home (estimates for the cost of power would be very similar to current utility rates) and charge indefinitely. A family building a house in the country could even tie into an onsite propane tank (many people in rural areas are supplied with propane instead of methane) to supply all of their electrical needs—cheaply, quietly, with great efficiency and far lower emissions, extremely low pollution, much greater lifetime because of the operating cycle and finally, with great reliability as well. And again, all of this at a cost that is only marginally greater than the basic price of the PHEV (The onboard inverter would require only slight modification to add 60 Hz, 120 volt AC).
What I propose involves no “breakthroughs” in technology; hybrids exist—this is a fact—and creating a design that satisfies the requirements I’ve laid down is technically and economically feasible—it will work!
And to put the “icing on the cake”, consider this: It is an extremely simple matter to store renewable fuels like alcohol. I can refuel my hybrid car with nothing more than a simple funnel; I can literally carry alcohol in everything from an empty plastic milk jug to a child’s beach ball. Ethanol, if spilled, dilutes in the groundwater and is bio-degraded in several days to acetic acid or vinegar (methanol degrades, biologically, in a somewhat different pathway) and finally, CO2 and H2O (this is a normal biological reaction). I can easily store, indefinitely, 55 gallons of ethanol or methanol with confidence and the greatest of ease. Contrast this with hydrogen: I can only store about 2-3 gallon equivalents of this in a car; when it’s used up, the only place that I can get fuel is from a hydrogen filling station; that’s moot since, during a massive power outage, there’s no electricity to run the pumps. Alcohol, on the other hand, can be easily dispensed with nothing more than a hand pump if necessary and no worry about containment.
Even if you could somehow manage to get a hold of a tank of compressed hydrogen with the intention of walking back to your stalled car, consider the fact that fully 95% of the weight of this fuel is due to the tank itself: One gallon equivalent of hydrogen (one kilogram) would require a tank weighing something near 50-100 pounds and would only be able to deliver ½ of the fuel contained in the tank to your car (the tank would only transmit fuel until pressures were equalized—hence the fact that only ½ of the fuel would be delivered). Alcohol, would be much less problematic: by far, the weight of the container is only a small fraction of the total weight; you could easily transfer ½ gallon of fuel (remember that one gallon equivalent of hydrogen will only be able to transfer ½ gallon of actual fuel) weighing only about 4 pounds—hardly a daunting task!
Hybrid cars are the most sensible approach in this author’s opinion, moreover, there is nothing in the hybrid design that precludes the use of a fuel cell down the road when (and if) such technology matures. Why not use what we have now instead of what we think we might have later?
Myth #4, page 1, 2nd paragraph:
“For example, even under conservative assumptions about car design, a good reformer making hydrogen for fuel-cell car releases about 40% to 67+% less CO2 per mile than burning hydrocarbon fuel in an otherwise identical gasoline-engine car. That’s because the fuel cell is 2–3 times more efficient than the internal-combustion engine, and methane has twice the hydrogen/carbon ratio of gasoline. (It’s possible, with some difficulty, to reach contrary conclusions by making sufficiently peculiar design assumptions, and some U.S. studies have done so, but we should be comparing good designs, not bad ones.)
The “2-3 times” premise appears frequently in Mr. Lovins’ analysis; indeed, it occurs so often that it might prove expedient to refer to it in the future as the “2-3 premise”. What makes this so disturbing is why, after having previously admitted in myth #3 that an FCV is only “1.5 times higher [more efficient] than the gasoline-hybrid-electric car”, he would then choose to return to the “2-3 premise” in making his comparisons. Certainly he is mindful of the fact that if we compare an HEV to an FCV that is only “1.5 times” more efficient, the conclusion he then makes will have been rendered false; i.e., a fuel cell vehicle will now emit the same amount of CO2 (possibly more) as a hybrid.
Even more surprising is the last sentence. If we take Mr. Lovins’ own advice; i.e., “comparing good designs, not bad ones”, then why not compare a high-compression, natural gas HEV of “good design” (instead of a low-compression conventional “gasoline-engine car”) to an FCV? This point needs to be driven home: The overall efficiency of a well designed HEV and an FCV will probably come out the same, in which case, all arguments predicated on a “2-3 times” better efficiency will be invalidated and we will then find, because of reformer losses, that a fuel cell car now emits considerably more CO2 compared to an HEV.
Myth #6, page14, 2nd paragraph:
“Invented in 1839…fuel cells have been widely used for decades in aerospace and military applications, where they’re prized for their ruggedness, simplicity, and reliability. Now they’re rapidly emerging as power sources for portable electronics and home appliances (such as hand tools and vacuum cleaners), due to market by 2004–05.”
Unfortunately, predictions, by their very nature, are subject to embarrassing scrutiny long after they have been elucidated. As of this writing (April of 2004), I have seen none of the “rapidly emerging” power sources that Mr. Lovins has spoken of (the methanol fuel cell for laptop computers may be an exception and I welcome its introduction—when it appears). “Coleman” was planning on offering a fuel cell generator sold through Home Depot last year, but it is still not available on any store shelf. Fuel cell products have been “coming down the pike” since 1991; auto company executives have decreed that, “the reign of the piston engine is coming to an end”—okay, where are the fuel cells?
No doubt, fuel cells will find markets, albeit very special ones at that, but it’s going to take an enormous reduction in price and complexity before fuel cells make an entry in the general consumer market let alone the transportation sector.
Readers should be wary of the approach Mr. Lovins has taken in his paper; many of his arguments are built upon predictions that are impossible to prove one way or another; this is inappropriate for a meaningful discussion on the technical merits of whether or not to invest in a hydrogen economy. Here are some more examples that occur in Myth #6:
“Continuing advances in both the fuel-cell “stack”…make it realistic to expect fuel cells to start competing with grid electricity in general use (i.e., at about $500–800/kW if no distributed benefits are counted) within this decade, and even with internal-combustion engines by around 2010 in carefully integrated vehicle designs needing ~$100–300/kW.”
It’s going to take a much greater price reduction to achieve what Mr. Lovins has in mind; consider this recent report:
"The first cost of fuel cells is very high compared to those of other DER technologies. The only product available commercially today is the PC-25T built by UTC. The 2001 cost of the unit is approximately $4,000/kW. The installed cost of the unit approaches $1.1 million. At a rated output of 200kW, this translates to about $5,500/kW, installed. Other fuel cell types are less developed." [web reference]
Moving on to the very next paragraph:
“In the next few years, more durable membranes and manufacturable designs are widely expected to permit rapidly expanding mass production of fuel cells for both vehicles and buildings. Once those innovation triggers have occurred, then as for most other manufactured goods, real cost should fall by ~20–30%70 for each doubling of cumulative production until limited by the cost of the basic materials. In very high volume, production cost of a low-temperature fuel-cell stack can ultimately reach a few tens of dollars per kilowatt, comparable to or less than the cost of internal combustion engines, which have been refined for more than a century and are produced in enormous volumes.”
Mr. Lovins’ claim is built on the initial premise of what to “expect”; he uses this premise to arrive at the conclusion of “expanding mass production” which, in turn will now make fuel cells amenable to falling costs that apply to “most” manufactured goods. He then invokes the principle that the lowest price will be limited only by the material cost and this “can” bring down the cost of fuel cells to only a “few tens of dollars per kilowatt”.
Contained within this paragraph are some very “iffy” terms—“can, expect, should”—why, should we allow someone else’s expectations to guide us? It was expected that nuclear power would be so cheap as to make it unnecessary to meter it at one time; it was expected that we’d be flying to work in our own personal gyrocopters; it was expected that we’d have a base on the moon by this time— an expectation is fine for stimulating conversation and ideas but invalid for proving a point. Furthermore, I would tend to disagree with Mr. Lovins on the notion that prices are limited by the cost of materials; there is another limitation that comes into play long before this occurs—the total manufacturing costs (exclusive of the cost of the “basic materials”). Here are a few examples that describe the notion: An automobile engine contains only a few tens of dollars in steel and miscellaneous components, yet the actual cost after more “than a century of refinement” is still several thousand dollars. The basic material used in an order of large French Fries can be bought for less than a penny, but MacDonald’s has the gall to charge several orders of magnitude higher for this tasty delight! It’s probably safe to say that the auto companies and MacDonald’s have pretty much reduced the cost of their product to the bare minimum while preserving the quality.
And here’s another point that needs to be thought about: The fuel cell actually predates the advent of the internal combustion engine; it has had at least the same amount of time to develop. It may be that the internal combustion engine “survived” over the fuel cell by virtue of a kind of Darwinian technological “survival of the fittest”—call it “Techvolution” if you will—and the fuel cell simply couldn’t compete. Perhaps this may change one day, but the internal combustion engine has many things going for it and is tremendously good at adapting; it may not, contrary to some predictions, “go the way of the dinosaur”.
A fuel cell and its various systems, on the other hand, constitute a very complex system; any claims that it will “ultimately reach a few tens of dollars per kilowatt” need to be considered with sobriety.
“FedEx and UPS reportedly plan to introduce fuel-cell trucks by 2008. Many applications are being pursued for scooters, recreational vehicles, boats, and even large ships.”
“A Deutsche Shell director predicted in 2000 that half of all new cars and a fifth of the car fleet will run on hydrogen by 2010, while the German Transport Minister forecast 10% of new German cars.”
These are all examples of using predictions to bolster a position; the problem is, as mentioned a moment ago, that predictions are not in the same category as reasonable and quantitative proofs.
Myth # 6 started out by saying:
“We don’t have practical ways to run cars on gaseous hydrogen, so cars must continue to use liquid fuels.”
Cars do not have to run on liquid fuels, indeed many fleet vehicles run on natural gas, but the advantages of liquid fuel are numerous, including as they do the following: they are very easy to contain; they hold an enormous amount of energy in a small volume relative to gaseous fuels; they are easily transferred with a minimum of equipment; they can be seen in the event of a leak; they generally have an odor; they can be recovered, in the event of a leak, without the necessity of separating them from air as would be the case with gaseous fuels; their containers are of the simplest and least expensive nature to build.
These are just some of the many reasons why we use liquid fuels and why the “myth” is perhaps more accurate than Mr. Lovins has made it out to be.
Myth #7, page 16, 2nd paragraph:
“Such carbon-fiber tanks could be mass-produced for just a few hundred dollars, and can hold ~11–19% hydrogen by mass, depending on pressure and safety factor. A 345-bar hydrogen tank (2.7 MJ/L at LHV and 300 K) is nearly ten times the size of a gasoline tank for the same energy content. However, the 2–3-fold efficiency advantage of the fuel cell, i.e., less energy expended per mile, compared to a gasoline engine reduces this enlargement to ~3.2–4.8-fold — even less when you include the saved size and weight of other parts of the car that are no longer needed, such as the catalytic converter. That factor shrinks still further — making the hydrogen tank only modestly bigger than a same range gasoline tank in today’s cars, but far lighter — when cars are designed to use two-thirds less power to move them, hence two-thirds less stored hydrogen for the same driving range.”
There are many problems with this paragraph so let us get right into it:
1) Making a carbon-fiber tank for a “few hundred dollars” is questionable since a stamped metal (very inexpensive both in terms of materials and manufacturing) automotive gasoline tank runs anywhere from one hundred to several hundred dollars at the auto store—it seems doubtful that the price will be lower than several thousand dollars considering the material, size and safety devices (will it have a turbo expander built into the tank or will it be throttled internally?).
2) A 345 bar tank is one scary thing to think about. Do you remember the high school shop class safety movies where they showed an ordinary steel pressure cylinder (100 bar) that was ruptured and went through a couple of cinder block walls like a rocket? There has been much talk about the safety of a hydrogen tank; we’ve all seen them in fires and watched as bullet were fired through them, but I keep thinking about the backyard mechanic who drills a hole in his car to route wires for his stereo and…well, give it some thought.
There is also the concern that occurs during the filling operation; unless the hose seal is gas-tight (“hydrogen-tight” raises the standard for leak integrity even higher), 345 bar hydrogen is an awfully powerful force to reckon with. If a leak should occur while a customer was filling their tank, the sheer force of the escaping gas (assuming it didn’t ignite) would have disastrous consequences for the person’s hands and face. Liquid fuels are much more benign in this respect.
3) Mr. Lovins uses the “2-3 premise” again in reducing the size of the hydrogen tank. Dismissing this premise brings us right back to “10 times” or more in tank size.
4) Eliminating the weight of a catalytic converter will theoretically increase range but due consideration must be given to the fact that an FCV is an intrinsically heavy car as evidenced by the Honda FCX at 3,900 lbs. Any imagined improvement due to the elimination of a catalytic converter is more than compensated by the FCV’s other unique requirements—like a 40% larger radiator (FCVs require larger radiators due to their operating temperature), heavier fuel tank and turbo expander to recover compression energy of the stored hydrogen (this alone will weigh as much as the catalytic converter) to name but a very few items.
5) The last sentence of the paragraph is actually quite baffling:
“That factor shrinks still further — making the hydrogen tank only modestly bigger than a same range gasoline tank in today’s cars, but far lighter — when cars are designed to use two-thirds less power to move them, hence two-thirds less stored hydrogen for the same driving range.”
Would not this improvement apply with equal validity to the tank of a HEV? The factor remains the same since the fuel requirements are lessened by the same proportion.
Myth #8, page 20, 1st paragraph:
“Compressing hydrogen to fill tanks to 345 bar using standard 93–94%-efficient intercooler technology takes electricity equivalent to about 9–12% of the hydrogen’s energy content. However, most of that compression energy can be recovered aboard the car by reducing the pressure back to what the fuel cell needs (~0.3–3 bar) not with a throttling valve but with a miniature turboexpander like a supercharger run backwards. In addition, where the compressor’s externally rejected heat can be put to good use, it need not be wasted. And compression energy is logarithmic
— it takes about the same amount of energy to compress from 10 to 100 bar as from 1 to bar, so using a 690- instead of a 345-bar tank adds only one percentage point to the energy consumption, raising the compression energy from ~9–12% to ~10–13%. Modern electrolyzers are therefore often designed to produce 30-bar hydrogen, and some electrolyzers in advanced development yield 200 bar, at only a slight efficiency penalty. This can cut the compression energy required for filling a 345-bar tank by half or by three-fourths, respectively — i.e., to only ~3–6% of the hydrogen’s energy content.”
The ability to recover compression energy is certainly true; what is of concern is the efficiency map for the turboexpander over the full range of hydrogen delivery rates. The best you can hope for is about 70-80% recovery at one particular region of the power curve (it falls of rapidly, especially on the low speed side); this is a questionable point however, since the turboexpander will add both cost and weight to the total system. More importantly is where the turboexpander would be placed in the system: Unless it is integrated within the tank, you will have a high pressure pipe and its attendant vulnerability to deal with; on the other hand, locating it within or as part of the tank brings certain service questions to bear—it gets complicated very fast.
The last part of this paragraph takes an interesting turn: were we not told that hydrogen would be produced from natural gas because of the excessively high cost of electrolytic hydrogen? The numbers given are certainly credible but they are not applicable to natural gas (you can’t electrolyze it); in that instance we would find numbers that are closer to 20% of the energy contained in the hydrogen if we assume that the electricity to run the compressor system came from another fuel cell (this could be reduced to about 10% if we used electricity direct from a PV panel or wind generator.).
Again, because of the complexity issues that arise when contemplating these systems, the numbers can take a turn for better or worse depending on who sees what. Generally, the fewer the components that are part of analysis, the more likely one is to arrive at numbers that are reasonable; It seems that one or more of “Murphy’s Laws” might apply here.
Myth # 9, page 20, 1st paragraph:
“Using illustrative, rather conventional fuel-cell cars nominally 2.2 times as efficient as gasoline cars, onsite miniature reformers made in quantities of only some hundreds, each supporting a few hundred fuel-cell vehicles and using natural gas priced at a robust $5.69/GJ or $6/MBTU, could deliver hydrogen into cars at well below $2/kg. That’s as cheap per mile as U.S. untaxed wholesale gasoline at $0.90/U.S. gallon or $0.24/L. (U.S. retail gasoline taxed to a ~50% higher price is still cheaper than bottled water.”
As of this writing, natural gas has increased dramatically in price but that’s actually quite moot; Mr. Lovins has invoked the “2-3” premise again. If we agree that FCVs and high compression HEVs are about equal), then the conclusion does not follow (just the opposite occurs!)
Continuing with the last paragraph of this myth:
“However, small-scale electrolyzers — now entering the market for demonstration and remote-location use — avoid the cost of hydrogen distribution from remote central plants, and in some circumstances they may compete with the decentralized gas reformers that offer the same advantage. Specifically, mass-produced (~1 million units) miniature electrolyzers, each serving a few to a few dozen cars, could produce hydrogen competitive with taxed U.S. gasoline even using 3¢/kWh off-peak electricity, so household-to-neighborhood scale could become a successful electrolysis niche market if enough units are made.”
I think the old “2-3 premise” is sneaking around somewhere in this paragraph! Well, let’s get started with some more realistic numbers. First, small electrolyzers are generally very inefficient (50-60% overall), effectively doubling the price of energy from 3 to 6 cents/kWh. Since 1kg of hydrogen (or a gallon of gas) contains about 36 kWh of thermal energy, this works out to $2.16 /kg H2 or, if we tax hydrogen auto fuel at the same 50% rate that applies to gasoline (why Mr. Lovins seems to think that hydrogen will not be subject to the same fuel tax as gasoline is a mystery), we end up with an actual cost of roughly $3.32 per gallon-equivalent of hydrogen. Now, even using Mr. Lovins’ “1.5 times” more efficient use of fuel in an FCV compared to an HEV, we find that the actual cost per gallon relative to $1.25/gallon gasoline is more like $2.20 /gallon-equivalent of hydrogen—assuming, of course, that you can supply electricity at 3 cents per kWh. Again, his conclusions are just the opposite of reality!
Actually, it is very confusing why Mr. Lovins keeps making comparisons to gasoline; why can’t we run hybrids on the same natural gas that he assumes will be reformed into hydrogen? One of the many fallacies in his arguments is based on his insistence of comparing hydrogen that is untaxed, to gasoline that is taxed 50% higher than its wholesale price. If he really wants to bring his point home, why not make a comparison to gasoline purchased in Europe where the taxed price is currently over $5 /gallon? Perhaps it’s because the absurdity of the argument would then become all too obvious.
“Since renewables are currently too costly, hydrogen would have to be made from fossil fuels or nuclear energy.”
Rather than list the various instances in this myth that are troubling, let me point out that the premise of the myth is actually true; i.e., “renewables are currently too costly”. While Mr. Lovins contests the conclusion, he does little to invalidate the premise. Instead, you will find that he lists several techniques that generate hydrogen from fossil fuel sources which is exactly the conclusion stated in the myth above; he has only lent credence to the so-called myth.
As of this writing, nuclear power is being seriously reconsidered in this country. President Bush supports the idea and even Scientific American’s April 2004 issue hosted a 4 page advertisement from Exxon Mobile and the NEI that extols the virtues of nuclear power—small wonder since the nuclear industry conceived of and promoted the concept of the “hydrogen economy” in the early ‘70s.
The fact of the matter is (like it or not) that 20% of the electricity in this country is generated via nuclear; it is arguably a relatively constant source of energy unlike wind and photovoltaics. Like coal, it is abundant, but unlike coal, it does not pollute the atmosphere with SO2, NOx and mercury, and this is why it is a little naïve to think that nuclear will not make a resurgence, especially since it offers to create “environmentally friendly hydrogen”. The only glimmer of hope that will preclude its unchecked return is, as Mr. Lovins points out, the fact that it is expensive—not to mention that little problem with waste disposal. I personally oppose a return to nuclear power—I hope, as does much of the world, that nuclear will slowly be phased out—but it is anything but dead and the hydrogen economy may, unwittingly, find itself involved in a questionable alliance.
Wind may well be cheaper per kWh (if you don’t include its capacity factor of 35%) compared to nuclear (capacity factor of 75% and higher depending on how it’s measured), but it must be remembered that wind is a very capricious energy source; it makes sense as long as it supplements base load generation (up to 20%). If we want to increase the amount of energy derived from wind beyond this, we will have to start talking about storage (hydrogen of course). But this will increase the cost per kWh generated, especially when one considers the economics of providing storage to cover all the energy generated by the wind (an impossible but illustrative point); nuclear relaxes this storage requirement dramatically (as does coal). This is why at some point, nuclear may begin to look more attractive economically and even, perhaps, aesthetically.
Mr. Lovins mentions that it is not “generally true that electricity from renewable sources is uncompetitively costly, leaving no climate-safe source to run electrolysis except nuclear power”. He provides some very interesting, mostly predictive and optimistic thoughts on why this is may be true, but this is moot: even if nuclear is too expensive, hydrogen derived from natural gas is still cheaper than renewably-generated electrolytic hydrogen (Mr. Lovins admits this). We are, therefore, forced to accept the conclusion of the original myth; i.e., “hydrogen would have to be made from fossil fuels or nuclear energy”. The point is that hydrogen will not be made from renewables as long as it can be made more inexpensively from natural gas (a fossil fuel), and that was exactly the contention of the so-called “myth”. One might argue that when natural gas becomes scarce, this argument will no longer apply—indeed, I believe that day is fast approaching, but we must remember that hydrogen can also be produced from coal, a resource that is claimed to represent more than several centuries of supply.
All in all, it would appear that as long as there is a cheaper way in which to manufacture hydrogen (and fossil fuels win hands down), then you can bet that Americans will take the most inexpensive route which only goes to show that the “myth” is probably a lot more true than we would care to admit.
Moving on to page 24, part “b” of the same myth:
“This concern is partly prompted by allegations — probably unprovable either way — that the Department of Energy may have diverted funds that Congress voted for renewable energy R&D into fossil-fuel hydrogen programs. Such diversion would be illegal and unwise. A similar re-allocation is regrettably proposed in the President’s 2004 budget, which seems to take hydrogen funds mainly out of efficiency and renewables. But both many renewables and many hydrogen programs are worthwhile and important for national prosperity and security, they support each other, and their diversity is inherently valuable, so we should do both, not sacrifice one for the other. Trading them off would be a sign of uninformed and therefore poor policy, not a demerit of hydrogen.”
One can view the last part of the paragraph with some measure of sympathy; it would indeed be sad and wrong to dismiss hydrogen and fuel cell research, but the distinction must be made between research and policy and how money is to be allocated to either. Hydrogen and fuel cells should receive money to continue their development, but the greater share of those funds should have been directed towards programs that are undeniably effective such as rebates on hybrid cars, PVs or solar water heaters; these programs would do far more in promoting a sensible energy future and would also foster the development of the technology to support it.
Perhaps even more effective (and contentious) is a move to raise the price of gasoline as is done in Europe; the effect would be two fold: it would “stimulate” the move to more efficient cars and provide revenue to support the various energy programs—including fuel cells and hydrogen.
I disagree with Mr. Lovins’ last sentence. Sometimes we need to recognize where the money is best spent and place one program above the other or else we could lose it all. Besides, no one is saying that we should abandon hydrogen; some of us simply think that it should retain the status of “investigative research” until (and if) it actually reaches maturity. In the meantime, I think it is because we are informed that some of us have questioned the proposed role that hydrogen will play in the immediate future and therefore, not a sign of “poor policy”, but rather, just the opposite.
Continuing with “myth #12, page 25:
“?The 2–3-fold more efficient use of hydrogen than gasoline in the car means that at the wheels, the equivalent of $1.25/gallon ($0.33/liter) U.S. retail gasoline is electricity at about 9–14¢/kWh with a proton attached to each electron. Since electricity sells for only about 2¢/kWh in competitive U.S. wholesale markets, the proprietor of, say, a hydroelectric dam or windfarm can get a 4–8-fold better price (even more in higher-priced countries) by turning a raw commodity (electrons) into a value-added product (hydrogen) through electrolysis. Splitting the water and delivering the hydrogen will typically add far less cost than that higher price earns.”
Rather than spending a lot of time explaining the problems with this paragraph, I’ll begin by citing the most obvious error—the “2-3 premise”. But even this doesn’t compare to the singular flaw in his reasoning: Mr. Lovins is again basing his analysis on the use of a fuel (gasoline) that is not only taxed 50% higher than it’s wholesale price, but is by no means the cheapest fossil fuel source from which to make hydrogen. Furthermore, the absurdity of this argument becomes even more apparent if we allow, for a moment, a world in which FCVs reign supreme. The argument then reduces to this simple question: what is the cheapest source of hydrogen— renewably generated electrolytic hydrogen or reformed natural gas hydrogen? Mr. Lovins had supplied the answer earlier on page 20, last paragraph—in his words:
“Splitting water with electricity can seldom make cheaper hydrogen than reforming natural gas unless the electricity is heavily subsidized, bought at very low offpeak prices (usually well under 2¢/kWh), or at very small scale (a neighborhood with a few dozen cars); that’s why only a few percent of the world’s hydrogen is now made electrolytically, powered mainly by old hydroelectric dams.”
What are the actual numbers for the cost? Mr. Lovins has kindly furnished those as well (footnote #83 of his paper):
“The variable cost economics are straightforward. An 85%-efficient reformer converts, say, $4/GJ HHV or $4 ??1.11 = $4.44/GJ LHV natural gas into $4.44/0.85 = $5.22/GJ LHV hydrogen, or $0.63/kg. With 75% (LHV) electrolyzer efficiency, since 1 kWh contains 3.6 MJ, $0.02/kWh yields $7.4/GJ or $0.89/kg hydrogen…”
So, it becomes clear that it is cheaper (31%) to generate hydrogen from a non-renewable fossil fuel (natural gas) than the cheapest renewable source ($0.02/ kWh hydro). But this is not the complete story, since the numbers are based on the implicit assumption that $0.02/kWh electricity is as plentiful as natural gas; it is not. In fact, the hydroelectricity that Amory uses in his analysis represents a very limited resource in America, having been fairly well developed and accounting for only about 1% of all the electric energy this country generates.
Mr. Lovins likes to use wind in his analysis, but if we consider the bus-bar price of wind-generated electricity quoted earlier by Amory (page 23, bottom paragraph), the case for natural gas becomes even more compelling: At $0.042/kWh, renewable wind electricity comes in at $1.87/kg of hydrogen, or more than twice the cost of reformed hydrogen; this from what he refers to as “…cheapest new bulk power source known…”.
Having made these points, we find the argument to be fallacious and are forced to accept, once more, that myth#12 is in reality, no myth at all. Continuing…
“Thus Assistant Secretary of Energy David Garman got it right when he wrote: “Over the long term, we want to make our hydrogen from sustainable, renewable energy, and that is where the majority of our hydrogen production R&D is focused. But if environmental advocates persist in the notion that all hydrogen must come solely from renewable energy in the near term, they will only ensure our continued and growing dependence on foreign oil.”
I really don’t know what to make of this paragraph. If ever there was reason not to believe in hydrogen, this one takes the cake! First off, if we grant for a minute (just a minute mind you!) that hydrogen is the way to go, then I think we must insist on it being done exclusively from renewables for the simple reason that to do otherwise, turns hydrogen into a non-renewable source of energy—by definition!
Granted, one can argue that PVs and wind generators are “imbedded” with non-renewable energy, but remember, these devices are “renewable-energy breeder reactors” (I really hate to use that term but it’s so effective), creating more energy than was necessary to fabricate them; once you burn hydrogen that was created from non-renewables, you have, unequivocally, consumed a fossil or nuclear fuel and hydrogen served only as a veil for that fact (“if you put a dress on a pig, it’s still a pig”).
And finally, we arrive at the last section of myth #12, page 26, bottom paragraph:
“Natural gas is at least a 200-year global resource, has only about half the carbon content per unit energy of oil, is far more widely distributed than oil (including major gas reserves in North America), and is generally considered to have greater geological and economic abundance and to be less depleted than world oil.”
This is a very interesting statement, especially in light of recent price increases in natural gas; even more so when one realizes that so provocative an assertion, in spite of the voluminous footnotes and references collected by Mr. Lovins, are not backed up in any way. Lacking any such citations let me list one from the document DOE/EIA-0216(2001) (November 2002). The document reports the U.S. reserves of natural gas as 183.5 trillion cubic feet. Using the current rate of U.S. consumption as 22 trillion cubic feet (we import about 17% from Canada) works out to about 8 years…assuming, of course, that we don’t use more of that gas to fuel a hydrogen economy.
Is it really possible that we have only 8 years of natural gas left? Probably not; these numbers are based on the term “recoverable reserves” and take into consideration what is “economically” feasible today—things can change dramatically in the next few years to make other reserves worth exploiting. But this calls into question what is meant by a “200-year global resource”; does this include all known reserves or maybe 50% of the total? Does his “200-year global resource” imply that we will be importing natural gas from other countries? Unless Mr. Lovins provides a reference that we can corroborate, I think it pays to use information supplied by the DOE or EIA.
Skipping over to myth #15, page 32, which states:
“There are more attractive ways to provide sustainable mobility than adopting hydrogen.”
Mr. Lovins’ proceeds to expose this “myth” by making several observations; here is the first claim that he attempts to refute:
“We should run cars on natural gas, not hydrogen”
His first response to this statement is as follows:
“Cars fueled with compressed natural gas or LPG have become quite popular in fleet markets and with some customers (especially government fleets, which must meet an alternative-fuels mandate) and in some countries (such as India and China, where conversions are cutting urban air pollution). They usually lower fuel and maintenance costs significantly and cut smog, but don’t compromise safety. It’s reasonable to suppose that hydrogen fuel cells, which provide all these advantages to an even greater degree, should win even more market support.”
Not true. Given that high compression natural gas HEVs will probably be as efficient, if not more efficient than an FCV, and the fact that no reforming is necessary, coupled with the 2/3 lower storage requirement (methane contains 3 times the energy per unit volume compared to hydrogen), it becomes unreasonable to assume that hydrogen would win any market support.
He then moves on to counter the following contention:
“We should improve batteries and increase the required electricity storage capacity (battery electric driving range) of hybrid cars.”
This he does by saying:
“California has largely abandoned its mandate to introduce battery-electric cars because battery technology, as RMI predicted, was overtaken by hybrid technology, which will in turn be trumped by fuel cells”
Mr. Lovins does concede that BEVs will have a niche market but wants us to believe that HEVs will be “trumped” by FCVs. What he fails to realize is that no FCV has even come close to “trumping” an advanced HEV (remember the discussion about the Honda FCX and the Toyota EC-3?). Furthermore, the fact that an HEV can run on a variety of fuels dispensed from existing infrastructure that can be (in the case of a PHEV) charged up at home or work via renewable solar and wind electricity, makes for a very compelling set of reasons to develop batteries and hybrids over FCVs.
And, in the very last claim:
“If we have super efficient vehicles, we should just run them on gasoline engines or engine hybrids and not worry about fuel cells.”
He responds with:
“I think such competition will ultimately tend to favor fuel cells, because they scale down better, being inherently modular and probably having less fixed-cost “overhead” than engine-driven powertrains, with or without hybrid drive. Fuel cells also undoubtedly have more potential for maturation and simplification, and lower asymptotic costs at very high volume, than the internal-combustion engine, now highly mature after about a century of volume production.”
This remains to be seen and a simple argument will demonstrate why it’s unlikely: In order for a fuel cell to compete with conventional engines, it must drop from its current, pre-mass production price of $3,500/kw to about $35/kw (the current cost of automobile engines)—let’s see what happens if we think we can get it down to this price. Now, if we accept Mr. Lovins’ statement that fuel cells “scale down better, being inherently modular” as true (and it is), then we should be able to build a 30 kw fuel cell (about the size necessary to run a hyper car) for around $1,000—almost half the cost of a standard, natural gas, forced-air furnace and close to the same power3.
These two devices—a fuel cell and a natural gas furnace—convert a gaseous fuel into another form of energy—the fuel cell can produce heat and electricity; the furnace can only generate heat. The furnace has been mass-produced for more than ½ of a century; it resides in virtually every American home and is one of the simplest appliances imaginable, composed of little more than a cast iron burner and blower motor (modern units sometimes have a microprocessor) and weighs less than the 30 kw fuel cell system. On the other hand, an automotive fuel cell system4 is made up of anywhere from 200-300 individually gasketed, cell units; a special humidification system along with a 30 psi blower assembly, coolant pumps, 30 kw electronic inverter, 30 kw electric propulsion motor and dozens of additional components.
Is it reasonable to believe this system could be sold for ½ the price of a natural gas furnace? If we assume for a moment that this were true, then a simple question is begged: Why not heat homes with the fuel cell instead of a furnace (this is actually one of the better ideas—cost aside—proffered by hydrogen enthusiasts)—according to this calculation you could do this quite effectively and provide electricity at the same time, all for only ½ the price of a natural gas furnace. What’s more, if we eliminate the ancillaries—the hydrogen storage tank, inverter, electric motor and many other components that are specific only to a system designed for transportation—then we should be able to get the price down even further—perhaps ¼ of the price of a natural gas furnace!
The fly in this ointment of wishful thinking is the fact that a fuel cell system for automotive use is an exceedingly complex technology requiring many layers of inherently expensive materials. An internal combustion engine5, on the other hand, is a very inexpensive engineering marvel, comprised of essentially so much steel—a plentiful, recyclable and very easy material to work with. No, it is unreasonable to think that a fuel cell system will ever come down in price to anything approaching the absurdly low cost of an internal combustion engine.
This completes the analysis of “Twenty Hydrogen Myths”; I’ll make my concluding remarks in a moment but for now, I would like to finish up with the very last sentence written by Mr. Lovins in myth #15; there’s a prophetic bit of irony contained in his words:
“It appears, therefore, that the hydrogen economy needs super efficient vehicles a lot more than super efficient vehicles need the hydrogen economy.”
I couldn’t agree more; super-efficient vehicles have little need of the hydrogen economy!
After reading this paper, the reader might understandably conclude that my criticism of the hydrogen economy is unfounded and perhaps somewhat harsh—that it will ultimately harm rather than help the renewable energy movement. Such is not the case I assure you; rather, it is my aim to make certain that renewable energy is given every chance it deserves and that was the true reason for writing this paper. I can only say that after researching the subject, after applying the laws of physics and chemistry, I began to find that many of the basic tenets of the hydrogen economy seemed flawed; the topic was laced with simply too many pieces of misinformation, distortions and contradictions. What surprised me even more, however, was the often blatant disregard for the quantitative aspects of this subject—from people who should have known better. It was only when I began to look more deeply into the matter—beyond the simple and obvious violations of the physics—that a reason became evident for why the general public was so eager to embrace such a controversial subject as the hydrogen economy: it is, quite simply, the long sought-after energy panacea that Americans have been waiting for…or so it seems.
Perhaps a better view can be gained by considering two of the most salient facts surrounding hydrogen: (1) it can be used to store relatively large amounts of energy and (2) it is easily manufactured from a variety of sources including electricity and virtually any carbonaceous material.
Now the first characteristic is one that, while certainly true, is not the most important reason why interest in hydrogen is so strong…it’s the second reason that contains the answer as to why intelligent people choose hydrogen in spite of the science against it, namely, the ease with which it can be manufactured! Granted, this would hardly seem to be justification for disparaging hydrogen, in fact, it’s a very positive attribute of the gas, but there is a subtle concern buried in that statement as well—one that could dramatically affect our energy future.
To make this concern more apparent, consider the following: America may be facing shortages of natural gas and oil, but what it is not in short supply is coal—estimates run well over 300 years. But coal, while containing enormous quantities of energy in a very small volume, has a number of drawbacks: As a solid, it is not as easily dispatched as are the gaseous and liquid fuels that can be transported via pipeline; it can hardly be considered in the role of a transportation fuel, although Rudolf Diesel had originally designed his now famous engine to operate (unsuccessfully it turned out) on pulverized coal; and while it was used for many years as a home heating fuel, it was eventually displaced by natural gas and oil for obvious reasons (obvious to those who remember hauling the dirty fuel from a coal-bin; shoveling it into the fiery maw of a coal furnace and then removing the dusty ashes afterwards!). Coal is also a very polluting fuel, producing significant quantities of SO2, NOx, mercury6 (48 ton per year in America) and our old friend CO2. Unless a great deal of attention is paid to scrubbing the exhaust, coal-burning facilities represent a significant source of pollution. Granted, the power industry has made much progress in cleaning up these emissions, but they are still a long way from being “pollution free”.
All these reasons have conspired against coal, which once was highly regarded, both as a transportation fuel in locomotives and ocean liners, and as a heating fuel for homes and industry; it provided the energy for the burgeoning electric industry, released iron from its ores and was unquestionably the primary source of energy in this nation at one time. Natural gas and oil have largely supplanted coal in transportation and heating; coal has now been relegated to the primary task of providing centralized-generation of electricity—not an ignoble task, but a far cry from it’s former glory…until recently.
Coal is experiencing a promising comeback in the form of the proposed 7 Hydrogen Economy. The “promise” is based on the fact that coal, along with natural gas and oil, can be transformed—like the proverbial “frog into a prince”—into hydrogen; clean, safe and easily transported hydrogen, also known as the “forever fuel”!
Repackaged in the form of hydrogen, coal can literally be given “wings” and used to fuel everything from commercial and military aircraft to ocean liners and submarines; it can power our cars and trucks, heat our homes, supply us with electricity, fertilize our crops and hydrogenate our margarine; it can be made from any source of electricity—solar, wind, hydro, geothermal and even…well, even nuclear energy.
The flaw in this idyllic picture stems from a quirky little trait that humans share called avarice. For some strange reason, when given a bountiful supply of anything, the first thing we Americans do is “spend it like there’s no tomorrow”. The same will be true of inexpensive, non-renewably generated hydrogen; it will—pardon the pun—“burn a hole in our environmental pocket”. This is more than just idle speculation; our recent energy history is replete with examples validating this point: In the 1970’s and ‘80’s, America responded to the rising price of oil by implementing a national speed limit on highways of 55 mph in an effort to conserve fuel8. We built smaller, more efficient cars, formed ride pools and offered special parking benefits to ride pool participants and compact car owners; up to a 50% tax credit on the cost of a solar hot-water heater or photovoltaic system was initiated in an effort to promote renewable energy—these were sensible ideas that were correcting a wasteful and spiraling trend in America.
But things started to change in the late 80’s and throughout the 1990’s; slowly we began to abandon the philosophy of conservation and sustainability as oil once again became plentiful. First to go was the 55 mph speed limit. Next to succumb would be an end to the federal tax credits for the installation of solar devices; ride pools became a thing of the past along with special parking. But nowhere was our faltering regard for energy more evident than with the advent of the “Suburban Utility Vehicle”—“SUV” as it has now come to be known—and this trend continues, unabated, in such demonstrable examples of American overindulgence as the GM “Hummer”9 and Ford “Excursion”. For the record, I do not fault the auto companies; they manufacture a wonderful product and will sell us exactly what we want—which is, apparently, very large cars.
So how does the hydrogen economy figure in all of this? Quite simply it turns out. America has been offered a way to continue “doing business as usual”, driving big cars on very cheap hydrogen derived from coal and natural gas. But it doesn’t end there; even nuclear, while currently experiencing an unsure future, is trying to get into the act as well. Indeed, President Bush and Vice-President Dick Cheney are very interested in this possibility and are pushing for the introduction of nuclear-derived hydrogen.
There appears to be no real reason to conserve energy because coal and nuclear—fuels that are in abundant supply—can be reincarnated in the politically correct “green” form of hydrogen. We have been told that, at least for the “near term”, natural gas will be the feedstock that drives the hydrogen economy and this will ultimately promote the adoption of renewable energy. This rationale suffers from a major fallacy: Change only occurs when a system is stressed; it is unreasonable to think that America and the world will ultimately adopt renewable energy sources as long as there is a cheaper method of accomplishing that same task. We are, to quote Henry David Thoreau, “…as lazy as we dare to be,” and we can, quite literally, afford to be…for now at least.
The problem will be one of “too little too late”. We will have created an environmental mess long before we run out of coal, nuclear and natural gas; our thirst for cheap energy will drive us, more and more, into the affairs of other nations and political conflict will escalate in step with our desire for cheap energy.
We see this same sort of behavior being played out today with the push for fuel cells. Since California suspended its “zero emission vehicle” (ZEV) mandate (largely as a result of auto companies promising to meet those requirements soon with fuel cell cars), practical cars like the Toyota RAV4 Electric10 have been discontinued in spite of the very positive response from owners. The attention given to hydrogen and fuel cells is far outstripping its actual potential; this in turn is diverting attention away from the renewable side of the equation. This is a point that deserves special mention: The hydrogen economy is dependent upon a source of energy like, but not confined to, renewable sources such as PVs and wind; it can only transform energy that is already present or can be made by other means. Therefore, it will only be useful as long as, or more to the point, not until such time as, a source of energy is made available to it. In other words, “you can’t store what you don’t have”. And what hydrogen does not have at this time is a set of reasonable sources of renewable energy to drive it.
We have been taken in by the promise that non-renewable sources will eventually spur the development of renewable alternatives to fuel the hydrogen economy. This is false logic—sort of like “putting the cart before the horse” instead of the other way around. Currently, renewable energy sources (PV and wind) account for less than 1% of our energy portfolio. Storage doesn’t become an issue, at least for electricity, until renewables are providing at least 20% of the total installed capacity of utilities. We should not be concerned with storage until, and not before, we arrive at this number and likewise, our efforts should be directed at making these sources a practical reality first and foremost.
In terms of heating and transportation, we have, respectively, solutions in the form of solar heat and electroyltically generated methanol11 and methane (ethanol, depending on the process, can be added to this list). Not only would a high compression hybrid PHEV (mentioned earlier in the text) allow for incredibly miserly fuel consumption, but, as previously mentioned, it would lend itself nicely to home and work-based renewable recharging.
The number of practical options is immense; we can ill-afford to ignore them in favor of putting all of our “energy eggs in one basket” as would be the case with the proposed hydrogen economy. Moreover, as shown earlier, there are good reasons to doubt the veracity of the claims proffered by the hydrogen enthusiasts. We have been told that the hydrogen economy is “emerging” but the question still remains: what will be the primary source of energy that drives it? Unless we can stop kidding ourselves into believing that a non-renewable “transitional approach” will make this a reality, we are in serious trouble. Time is growing short and we need to start making decisions that will provide real solutions, not hopeful ones.
April 16, 2004
It is with great appreciation that I wish to call attention to the kind efforts of both John Richter, who contributed his thoughtful review of the technical statements made in this paper, and Timothy Hudson, who has always pushed me to put into words, the connection between science and reality. To these gentleman and, more importantly, life-long friends, I am most indebted.
1a I have often seen this view in print; it is a serious error that has been perpetuated because of a confusion between a practical temperature limit due to materials used in the construction of an internal combustion engine (e.g., lubricants, seals, metallurgy, etc.) and a thermodynamic temperature limit; they are, as I explained in the main text, entirely different limitations and have nothing in common with one another. The misapplication of “The Second Law of Thermodynamics” is a common occurrence in the debate between fuel cells and internal combustion engines; it has created a series of mistaken premises that need to be corrected.
The resolution of this on going problem can be accomplished by considering two “reversible systems”: A “Carnot engine” operating between an upper temperature dictated by the enthalpy of the particular fuel/oxidizer combination, and an electrolytic cell operating with the same combination of fuel and oxidizer. Both of these systems are ultimately limited by the “Gibbs Free Energy” (ΔG=ΔH-TΔS) which takes into account the fact that even if we eliminate all dissipative “losses” (e.g., friction in the engine and ohmic loss in the fuel cell), we will never be able to convert all of the heat content of the fuel into useful work—some heat (the TΔS term) must always be transferred in the process and, consequently, is unavailable to provide useful work. The entropy term in the above equation (TΔS), when subtracted from the theoretical heat content of the fuel/oxidizer combination, or enthalpy (ΔH) will determine the available energy that can be converted into work (ΔG) and hence, the efficiency for either system; this in turn, is dependent upon the lower temperature (as is the Carnot engine) and is one reason why fuel cells, if they are to achieve a high theoretical (if not practical) efficiency need to operate at as low an ambient temperature as possible.
Contrary to what Mr. Lovins has stated, fuel cells are in fact subject to the very same laws of thermodynamics as a heat engine, specifically, “The Second Law”, and this in no way proves, or even suggests that “a hydrogen fuel-cell car can therefore convert hydrogen energy into motion about 2–3 times as efficiently as a normal car converts gasoline energy into motion…”.
The excerpt from the “Fuel Cell Handbook” (footnote “1b” below), gives a more lucid explanation of these maters.
1b “It is commonly expressed that a fuel cell is more efficient than a heat engine because it is not subject to Carnot Cycle limitations, or a fuel cell is more efficient because it is not subject to the second law of thermodynamics. These statements are misleading. A more suitable statement for understanding differences between the theoretical efficiencies of fuel cells and heat engines is that if a fuel cell is compared to an equivalent efficiency heat engine, the fuel cell is not limited by temperature as is the heat engine (5). The freedom from temperature limits of the fuel cell provides a great benefit because it relaxes material temperature problems when trying to achieve high efficiency.”
Fuel Cell Handbook, 5th edition, 2000
2 The overall efficiency of an internal combustion engine is often quoted as between 15 and 25%. These values are representative of the output efficiency at the wheels of a vehicle; efficiencies at the output of the flywheel are more typically between 30 to 35% and even higher for diesel engines. For a fuel cell power plant operating on pure hydrogen, the comparable efficiency breakdown at the output of the fly-wheel is roughly as follows:
Fuel cell efficiency: 40 to 50%
Air compression: 85% (uses 15% of gross power)
Inverter efficiency: 95%
Electric motor efficiency: 97%
Multiplying each of these values together yields an overall system efficiency of roughly 31 to 39%
3 A standard forced-air natural gas furnace has a heat rating of 100,000 btu/hour; this is equivalent to roughly 30 kw of power.
4 A point commonly ignored by hydrogen advocates is the fact that a fuel cell is only part of the entire system necessary in getting a shaft to turn; additional systems and components are required including, at the very least, an inverter and electric motor. An internal combustion engine has no need for these additional links in the “chemical energy-to-shaft energy” chain since it converts chemical energy into motion directly in one package—the engine proper.
Most cost estimates for the fuel cell system never take this simple fact into consideration and incorrectly quote a price for just the fuel cell stack alone while conveniently forgetting to include the price of the inverter and electric motor.
5 One might rightfully ask, “If an internal combustion engine is so inexpensive, why is it not possible to replace an existing gas furnace for the very same reasons outlined in the case of the fuel cell argument?” The answer is quite simple: An internal combustion engine produces too much vibration and noise if contained within a home. Moreover, there is the admitted danger of carbon monoxide poisoning in such confined quarters and the fact that oil changes would be required periodically. All of these objections are, for the most part, non-existent with engines used in a hybrid automotive setting.
Interestingly however, is the fact that at least one engine manufacturer has tested a residential outdoor heat pump powered by an internal combustion engine. The benefit here stems from the fact that the engine not only supplies heat but air-conditioning as well and avails itself of the heat pump’s ability to deliver several times as much heating or cooling for every heat unit of fuel consumed in the engine. A large, 5 gallon oil reserve, reduces oil changes to once every year and the engine heat pump system can be potentially employed as an emergency back up generator as well.
6 As of this writing, much concern over the levels of mercury contamination has been evinced: since mercury is a bio-toxin—it concentrates in the bodies of animals, most notably, marine life—it has been implicated in a number of cases involving birth defects. Our government has now issued warnings as to how much of certain kinds of fish we eat each week.
7 I stress “proposed” since many have been lead to believe that the Hydrogen Economy is a forgone conclusion; this is a matter of opinion and one of the reasons why this paper was written.
8 More than anything else, the desire, not the necessity, to drive at high speeds, has imposed constraints on vehicle design that are significant: As a car’s speed increases from 55 mph to 75 mph, the actual power consumed (and consequently, the size engine installed) becomes dramatically larger—over twice the size! This is primarily a result of the power expended that increases as the cube of the speed (while the tire resistance remains essentially the same, the air resistance force increases as the square of speed, but power is “Force x Speed”, hence the cube relation).
But this is not the only problem: When moving from a speed of 55 mph to 75 mph, the fuel consumption rises dramatically as well. In a conventional gasoline car this is not nearly as significant (perhaps a 20-30% increase in fuel consumption) because of the fact that an ordinary engine is more efficient at higher loads, partially offsetting the increased power requirement. But, in an FCV (whose efficiency goes down with load) and HEV that has been designed to reduce rolling resistance (consequently increasing the relative loss due to air resistance) as much as possible, the difference in fuel consumption can rise to over twice the value at 75 mph as it would at 55mph!
Either way, one of the most effective ways to conserve fuel and with no technological breakthrough required, is to simply restore the original 55 mph speed limit. Clearly, Americans would rather waste fuel than spend a little more time in their cars. Paradoxically, we have the methods by which to reduce or eliminate our dependency on oil, but we choose instead to do nothing because the promise of the hydrogen economy allows us to remain complacent. This is the real danger.
9 The latest version of this vehicle contains a very interesting and, in some people’s mind, somewhat suggestive (and perhaps deliberate) example of “green washing”: near the driver’s door is the symbol “ H2 ” which ostensibly stands for “Hummer Two”. Of course, this just also happens to look very similar to the chemical symbol for hydrogen gas. Now some people might just say this is simply a coincidence while others have argued that GM deliberately was aware of the subliminal effect this would have on the perception of the vehicle—who really knows?
10 The RAV4 Electric car was, arguably, the first really practical electric vehicle: with a range of 120 miles per charge and an equivalent fuel cost per mile about half that of an identical gasoline engine RAV4, the electric version could be charged at home or the office; it never needed an oil or antifreeze change and it was as quiet as one could hope for. Unfortunately, Toyota discontinued sales and this will stand as one of the saddest days in the history of renewable energy solutions.
11 Methanol and methane can be manufactured from hydrogen that’s produced electroyltically and, consequently, renewably from wind and photovoltaics. The process is interesting since it uses, or can use, ordinary CO2 from the air or from other sources such as the waste product from the fermentation of biomass to ethanol. What makes this technique so interesting is the fact that hydrogen is now coupled with carbon (and a little oxygen) to create a liquid fuel of extremely high energy density and practicality. The process compares very favorably in terms of energy efficiency (48%) with hydrogen produced electroyltically (65-70%)—more so when due allowance for the losses in compression and delivery of hydrogen are considered (50% overall). Moreover, when the other attributes of methanol and methane are considered—their ease of delivery, higher energy density, compatibility with existing infrastructure and engine designs, etc.—the reasons for choosing these fuels over hydrogen become obvious.
Using methanol and ethanol in HEVs—more specifically in PHEVs—allows one to decide when and how much of a precious liquid fuel is going to be consumed. Considering the fact that fully half of all cars on the road on any particular day will drive less than 25 miles round-trip (90% of all daily round-trips are less than 75 miles), the possibility of using little, if any, alcohol fuel becomes eminently practical.
The point is that a liquid fuel should literally come with a price; it should be regarded as a commodity of the highest value and used only when really needed as, for example, when driving some great distance—the “family vacation” and out of town business for example. America really needs to think seriously about raising the price of any transportation fuel in an effort to not only to discourage current wasteful practices, but to encourage more benign technologies like BEVs and PHEVs; the revenues gained could be used to provide subsidies for the purchase of renewables such as PVs and wind; conservation programs and other projects like bike paths would likewise benefit from the increased cost of fuel.