'EREI' We hear this term being used when describing the different forms of energy we receive through fuels, hydro, solar cells etc after we've used some energy to get the final energy. Now because of this I’ve started to wonder how can we figure the EREI for biological integrated farming systems?
For example what would the EREI be for a maximum energy efficient solar greenhouse?
http://attra.ncat.org/attra-pub/solar-gh.html with a barn built on the north side for housing small live stock so their breath (CO2) would increase plant growth, some body heat, manure for making methane & fertilizer, food; eggs, meat, milk and textiles; fur, hides, wool, feathers. Then if we keep adding integrated systems as we improve like permiculture ethanol production
http://www.permaculture.com/ in the back barn so the excess heat (from biochar production) and CO2 is once again harnessed along with the other useful by products for food production (fish, mushrooms, fertility). Now because of the biochar and organic fertilizers the plants will grow and harness greater amounts of solar energy, thus helping the whole system increase and improve.
If we could calculate the EREI on such a system which I’m sure would be very good and equal to or greater than energy systems many are dependant on now. If this could be done then we might have a tool to show people it’s worth $$$ their efforts to redirect their energies into learn about and creating such systems.
Digging