As energy costs rise, we are seeing a remarkable resurgence of new energy solutions. Old ideas are being dug up from the trash heap of history and enthusiasts are promoting perpetual motion machines, cold fusion, nuclear power, tar sands, "zero-point" energy and ethanol. Clean This and Smart That, Sustainable Solutions and Carbon-Neutral Technologies. Billionaires and mad scientists alike are seeking their way in uncharted waters, sometimes protected - at least until they plow our future into the ground - from the Second Law of Thermodyamics by government subsidies.

In this confusing arena, it is hard to separate the wheat from the chaff. In the USA, a self-appointed "national" commission with a big budget cites a fraudulent study to advance their hidden agenda, and well-meaning policy wonks (who know how to do library research but didn't do so well in high school algebra) gobble it up as if it were gospel.

We could stand by and watch from the sidelines if we had plenty of time and resources to rearrange things before the big crunch hits - say when global oil supply declines by 10-20% and everybody starts freaking out. Unfortunately, a temporary "transitional" solution could be more damaging than doing nothing. We would adjust to alternative fuels - tar sands, coal-to-liquids, ethanol, who knows what - and then these sources would run dry too. Then we would be completely in over our heads, even deeper than we are now, because we would have exhausted all the easy fossil fuels as well as the marginal sources (with more associated greenhouse gas emissions than conventional fossil fuels) without having built a viable, sustainable solution. This we cannot afford to do. We have to get it right. And there is no time to waste.

How do we go forward? Answers must come from careful analysis of energy alternatives based on scientific fundamentals, not expedient economic metrics. It is tempting but altogether too dangerous to base societal-level energy investments on economic models shaped by the policies which are causing the status quo to fail in the first place.

Many factors are critical to success, keeping the decision matrix full of complexities. I want to highlight just two key issues for the moment, and refer you to a matrix if you want to investigate options in greater depth. These two key issues are scalability and net energy.

Due to the visibility of the US presidency, two proposed responses to peak oil are receiving a great deal of attention - hydrogen and ethanol. The "hydrogen economy" is also a favorite theme in Europe. However, though it is represented as a potential energy solution, hydrogen doesn't even qualify as an energy source - it must be created at considerable thermodynamic penalty from natural gas, electricity, or other sources. Ethanol - from corn, sugar cane or cellulose - requires prodigious amounts of fossil fuel for processing and cannot be brought to scale without destroying our planet's remaining forests, cultivated lands and aquifers.

We can address the scalability of unconventional fossil fuel options, nuclear power, or renewable energy solutions by considering the ultimate recoverable amounts of fuels (including uranium) versus the staggering amount of sunlight that is imparted to the earth on a continuous basis. For example, all the conventional oil that has ever been consumed is equivalent to the energy of the sunlight intersecting our earth's surface (178,000 TeraWatts) for 12 hours. Turning then to the various forms of solar energy, in comparison to the average 13 TeraWatts (TW) of power actively produced by human ingenuity, it has been determined that, on land, the theoretical limit of photosynthesis is 7-10 TW, wind energy is 2-4 TW on land (more over water), hydroelectric is 0.7 TW and direct solar is at least 60 TW, making direct sunlight the most scalable source - if humanity can perfect the instruments at sufficiently large scale to convert sunlight into useful thermal, mechanical and electric energy.

Net energy can be likened to interest on a loan. Higher interest rates mean better returns; if your bank's interest rate is negative, your bank deposits shrink. Net energy returns of 100:1 in the early days of the oil bonanza made societal transformation possible. But now energy return on energy invested for new oil discoveries is typically 5:1 and declining, and because of poor uranium ore quality, the return for nuclear energy is of the same order, even before consideration of long term consequences. So, regardless of price and supply volatility, it makes sense to find alternatives which have a higher net energy yield. Such alternatives exist: at 50:1 or more, wind energy can deliver yields at the same order of magnitude as the oil fields of old. At 40:1, the latest thin-film solar cells can run circles around new oil in terms of net energy yield.

If we squander our remaining fossil energy reserves, either in profligate consumption or into solutions with poor energy yields, we risk global economic collapse. It is essential that we invest the energy in our finite fossil fuel reserves into solutions which can lift us out of the depletion cycle onto a stable, sustainable platform. [Ed.]

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