Okay, beer was once food. But as a general rule, it's safe to say that alcohol is not food. Yet we're willing to convert food calories to alcohol calories and then burn them in our cars rather than eat them. It's things like this that make me understand why Gaia is thinking about thinning the human herd.
Famine is one of those things on my mind these days. The UN is warning of food shortages and a crisis in distribution, prices are rising steadily as big money is finding big profits in speculating on food futures markets, and global warming is devastating worldwide production. But we still don't see the linkages between the diverse issues facing us--which, I have to say, leaves me batting my head against a wall. We love the "traditional" western diet, but it takes 700 food calories to produce 100 calories of animal protein. And that doesn't include the calories expended to produce the initial 700 calories. This is the same problem we're facing in fossil fuel production; eventually it takes more energy to produce a barrel of oil than a barrel of oil contains (the Alberta tar sands is approaching this already). That is simply unsustainable, whether it's food or oil--and particularly when it's food AND oil.
The oil shocks of the '70s showed a lot of ingenuity still exists to deal with problems. Mother Jones magazine ran article after article about people learning to distill their own alcohol and how to convert various machines over to run on alcohol. But most of these solutions had one thing in common; they were intended for individual production and use. When the Bush administration began encouraging the production of ethanol on an industrial scale, pressure was put on worldwide food stocks as food (mostly corn) was tapped as feed stock for the new production. Brazil went a slightly different route, using sugar cane as the feed stock. The downside for Brazil was the increased rate of deforestation, as trees were cleared to free land for cane production.
Back in the exurban US in the '70s, no one ever suggested using food for ethanol production. Instead, it was all about using waste. And no one expected full fossil fuel replacement--the best we hoped for was to reduce our use of conventional fuels. One of the problems faced by exurban Americans was that fuel ethanol and drinking ethanol were both produced the same way, and there was a lot of legal pressure brought to bear to ensure that fuel production didn't somehow become drinking production. And, truth be told, ethanol production for human consumption has always been more lucrative than production for fuel.
But there are several of these techniques that integrate food/waste/power production. There are small scale methane harvesters designed for small farm use (there's a home experiment version here) that convert plant and animal waste into useable methane and compost. Gerry Baron has built one in the Philippines that produces cubic metres of methane--enough for cooking three meals a day. And this tech has been discussed for quite a while. Popular Mechanics ran an article on the topic back in 1974.
Jane Jacobs, in Cities and the Wealth of Nations, writes about the theory of import replacement; that economic growth occurs as urban economies replace imported goods with their own manufacturing. Methane harvesting, composting, alcohol production, all of these can serve the same purpose for small and medium sized farms: The replacement of expensive imported goods with less expensive locally produced alternatives.