From a friend
One question I have about renewables in general is has anyone done a rough calculation of the energy and material requirements to actually ramp up a renewable energy regime that would allow some semblence of a complex civilization to continue operating?
...and the friend's subsequent message:
there is no comfort in understanding how much potential energy is available from the sun ...
Actually, for me, understanding solar potential in its various forms _was_ the first step to discovering a plausible path to sustainability. Our challenge is merely to discover what we have to work with and how to use it. (Grown-ups' first job is to figure out how to live within their means, after all.) I did a chart in my recent Solar Today article on page 17 (same issue as Bartlett's article referenced below)
In this chart you note that the sun delivers 120,000 Terawatts ("TW") to the earth's surface continuously, while humans generate only 13 TW = 1/100 of 1% of solar -- everything from nuclear power to firewood. From there you can see how much each form of solar energy might be able to deliver, conservatively at least 60 TW using direct solar, and various amounts for hydropower, wind, geothermal, etc.
WHAT WON'T WORK
You may note in the chart that the potential of annual photosynthesis is 7-10 TW (theoretical) -- and far less as a practical matter. Without even considering its emotional baggage, nuclear is demonstrably pathetic. For details, see these pages on my website:
THE AUTOMOBILE: INEFFICIENT IN THE EXTREME
The next thing to consider is not merely how much energy we will need, but what technologies can plausibly work, post-peak-oil? It has been especially hard for society to dream up a substitute for oil in the private car; we've gone from the New Generation Vehicle (Clinton) to the Hydrogen Highway (Schwarzenegger), cellulosic ethanol and plug hybrids (Bush). These all fall into the category of answering the wrong question. No _fuel_ per se is going to bail us out: the automobile itself will follow the Hubbert curve down. It is just too grotesquely dangerous and inefficient. The IC engine is maybe 25% efficient to the flywheel and the transmission to the tires drops that down to 10% (if you're lucky), so you might think we're doing pretty well. But gasoline pushes 4,000 lbs of parasitic mass (steel etc.) for every 200 lbs of people -- 5% efficient! So take 10% to the wheel x 5% people and the car is 1/2% efficient in converting gasoline to moving people. Drive a Prius or a Tesla and you're up to 1% -- congratulations! You're doing almost as well as the 1813 Puffing Billy.
Conclusion? Pervasive use of fueled vehicles, even electrics (Sorry, Greg!) or hybrids, cannot possibly survive peak oil. And good riddance! Yes, we may still have gasoline ambulances and fire trucks, but not commuter SUVs.
Is there an alternative? Yes. Several well capitalized groups are building personal rapid transit ("podcar") systems which will get 100's of miles per gallon equivalent. A continuous overhead solar panel about 4' wide will deliver all the power necessary to move podcars carrying over 20,000 passengers per day -- a freeway lane's capacity. Solar panels producing electricity without _any_ subsidies will pay off in 4 years compared to liquid fuels (gasoline). Costing less than 10% as much as light rail or "freeway" construction, Podcars are about to scale up rapidly. If implementation in the USA gets bogged down, America will be even further behind Europe and Asia.
Once upon a time, humanity made the connection between hay and horses, and people moved faster. In our times we juxtaposed oil and the automobile, and those of us who survived moved around faster. (Four members of my immmediate family didn't make it. Many of you have also lost friends and family to the automobile.) After peak oil, it will be 80% electricity and 20% fuel (if that), or we will be riding horses again.
Technology isn't the whole story by any means, but here again technology is playing a critical role. Solar manufacturing is capital intensive: $1 million invested in a factory will support 1 million watts of production per year. This is about to change.
I know I've only touched the surface, but the starting point is to realize that the only way out of our collective mess is to make real changes. In his State of the Union last night, Bush spoke of 35 billion gallons of alternative fuel in 10 years. If he's right, the planet is toast. We must deliver credible EROI analyses to our policy makers pronto, so we won't keep wasting so much time and effort, destroying our soils and our aquifers. And we need to demonstrate the physics (thermodynamics) and the economics of plausible technologies.
The rest of my Solar Today article goes into some detail about ramping up to solar. For example, see my graph on page 19. Jack, I can help you to further define the parameters so that our team can effectively calculate the human capacity, energy and materials needed to build a bridge to a world beyond oil.