It's fermented getting gas from it.
The gas is used to heat the greenhouses and the farmhouse and the town. Just natural energy.
Getting the climate better

And it is used to generate power for electricity for the machines.
And naturally, but that's been ruled out, it can be used to shorten the production time of crops. I'd like to produce tomatoes in 3 hrs
I don't know how complicated it can get, but the soupkitchen (fi) may use 4 energy equivalents per hour/day. Etc.
If you manage to produce more energy than needed, you get xp. Less energy could cost you xp.