But there's a huge existing fleet of internal-combustion engines in vehicles, generators, and tools like chainsaws and leaf blowers, etc. A locally-produced ecologically benign carbon-neutral fuel source is an important part of the solution, eh?
As for efficiency, consider: Scenario A: grow a crop of corn and feed it to pigs. Scenario B: grow a crop of corn ferment it and extract the alcohol and feed the leftovers to pigs.
In B you get two crops for the price of one. (Alcohol is produced by yeast from sugar. The leftovers are protein, the bodies of the yeast. The corn is a better feed after fermentation and alcohol extraction.)
As for land use in a permaculture farm you would be growing more than one crop on the same land at the same time. You might have two or three crops that produce food and some yams or sugar beets for fermentation.
Also, a lot of things you might not realize can be feedstocks. Pretty much anything with sugar or starch. Farmer Dave had a deal with a donut bakery to get their scrap dough for fermentation and fuel production.
Farm equipment is far more expensive than solar panels and batteries, not to mention the amount of man power to deal with the scale needed for fuel production. Plus the extraction equipment.
In option B you end up with a shit ton of fermented waste. The amount you’ll have to grow for fuel will feed 20x more animals than you’d have in a local/small farm.
You’ll need a lot more land than usual to try this. The soil will be depleted in a few years even if you try crop rotation as your options are limited for fuel production.
Unless you show me an example of this system working I’m very skeptic, a lot of wishful thinking.
Dude, there's a whole book about it.
> an example of this system working
And, yes, Farmer Dave did it. For all I know he's doing it right now. I haven't talked to him in years.
You can contact him right now and ask him to put you in touch with the people who are already doing this.