Try following

http://biopact.com/

for awhile and you’ll see what I mean.

It is not even the case that all biofuels have food vs. fuel problem. Algae biodiesel, for example, would not be produced in soil, but in “bioreactors” (one of the original proposals was to use the Sonoran desert).

The bigger issue stems from the fact that plants are an inefficient way to harvest sunlight, because photosynthesis is usually only 1% or so efficient at turning sunlight into biomass. That inefficiency translates directly into land area. Algae are interesting because efficiency can be as high as 7.5%, but even that pales compared to Concentrated Solar Power (CSP). For example, Stirling dishes are approximately 30% efficient at turning sunlight into electricity. That’s a factor of 4 to start (and CSP is getting better). But then combustion fuels can only be converted into work at efficiencies that are one fourth to one half of electricity. (While the efficiency of “heat engines” can be better than what we have in our vehicles today, there is a theoretical limit to heat engine efficiency from thermodynamics called Carnot’s theorem. Practical efficiencies are lower than Carnot’s limit though, e.g. approximated by the Callen efficiency.) In contrast electricity can be turned into work at very high efficiencies. Multiply the factor of 4-16 to start with 2-4, and you get a factor of 8-64 gap between biofuels and electricity. This is demonstrated by doing real calculations using yield data from the literature.

In contrast, just deploy today’s technology (no research required), and you find it would only take a few thousand square miles of CSP to power 420M Americans in 2050 driving 9,300 miles per year. CSP powered passenger travel, in contrast to biofuels, is not a niche technology; it is a solution. Remember also that land area equates to cost. CSP powered travel is several times cheaper than gasoline-powered travel today; in 2050 it should be enormously cheaper.

Fuel cells are not subject to Carnot’s theorem (they are not heat engines). However, they do have efficiency problems (much of the energy ends up as heat, rather than work). Since electricity is the most efficient way to get energy from the sun (e.g. wind or PV or CSP), converting it to hydrogen and then from hydrogen back to electricity introduces two conversions that are guaranteed to to lose efficiency (thermodynamics again). Keeping the energy as electricity is the best choice. If you don’t, and you make your hydrogen from renewable electricity, you’re going to pay three times per mile what it costs to use electricity directly. That makes no sense.

And then there’s the water issue. Where will all the water for biofuels come from in a global-warming drought-suffering world? Even using water to make hydrogen for fuel may be unwise given other pressing uses for water.

Except in the United States, with a quite stupid policy in place regarding corn, it seems to me the food problem is primarily due to too many people (some of whom, like me, eat too well).

Going to go have a big lunch, with meat, just now…