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« A creative solution for the car makers | Main | Is part of our problem that we are voracious informavores? »

November 24, 2008


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Cosmic Rays is the next source for energy since bombairds the earth 24/7.

Eric Hacker

Overall a very good post. I'm having a little trouble with the energy density comparison. I thought that with solar at 1.4 kW / m2 that you'd get 1.4 kilowatt-hour per square meter.

I also thought the comparison to coal was difficult to understand. Since transportation is a significant part of our oil usage I thought I'd try kWh per gallon. I came up with about 36 kWh / gal based on 34.2 MJ / l reported at

George Mobus


I did put some caveats on interpreting my numbers, and will readily admit I've been known to displace a decimal point from time to time.

The point of that paragraph was to emphasize the low density of sunlight and therefor the greater area needed and the concentration required to approach fossil fuels in their power delivery (energy units per unit time). I fudged a bit to try to make the point and my approach shouldn't be taken too seriously (especially by physicists and engineers who might prefer a finer point).

The Wikipedia link went to a service page. Did you have another specific topic link?


Eric Hacker

Silly Typepad included the period in the URL that most other programs do not do when the URL is at the end of a sentence.

I think part of the problem with energy density arguments with solar is that there actually is enough energy available for a similar lifestyle if we were to imagine something crazy like converting all paved road surfaces to solar panels. In other terms, if you or I decided to be more financially frivolous we could probably borrow enough money and get enough solar panels to power our car. Will everyone be able to do that anytime soon, if ever? No, but that fact that it might be attainable for a few individuals has some believing that the problem is essentially solved.

In case it is not clear, I agree with your message, but I've been told by many I am an extremist and this is easy for me to accept. I am trying to help refine the message so that people don't have as much wriggle room when confronted.

Tim the Optimist

Energy is only part of the problem. Imagine if we had a source of unlimited free energy, this would still not save our ever growing economy. In fact, free energy would simply enable the growth-maniacs to destroy the biosphere more quickly.

We need to address the question of unlimited growth, and I believe we need to attempt to transition to a stead state economy. In such an economy a free energy source would be a blessing, but in our present growth based economy, free energy would be a curse.

So I believe the question of "where will the energy come from" is secondary, the primary question should be, "is this never-ending growth economy sustainable" - regardless of where the energy comes from.

Cheers, Tim.

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