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Home biogas: turning food waste into renewable energy
(theconversation.com)
everything about energy production
Yeah, seems like they take up quite a lot of space, too. Only really an option if you live in the countryside or have a huge garden.
EDIT: Plus, the amount of food waste required seems quite high. Sounds like it would be most practical if you had some chickens or goats, or a really big family, to generate that amount of compost.