What if this "less-evolved" system is actually a step forward in our evolution as species? Because we use a lot of electricity for the machines required to create, maintain (and promote) our food, what if we could just skip that and directly plug the energy into ourselves?
It can be measured; here's a page listing the energy efficiency of various foods: http://www.theoildrum.com/node/6252. It appears it would depend on what we were giving up; if we replace meat with direct energy, we could save around 95%, for instance, but if we replaced grain with electricity we'd save much less, as grain is already fairly efficient.
Average Corn yield is ~160 bushels per acer. 60lb per bushel. An acre is 4,046 square meters. A square meter gets 1kw in full sunlight. Call it 8 hours a day of sunlight. Corn takes 63 to 92 days so you can get 2 yeilds per year in some area. Call it 72 for sweet temptation. 72 * 8 * 4,048 / 160 / 60 = ~242 kwh worth of sunlight per pound of corn.
Note: Solar cells are ~22% efficient but they also work all year.
