https://www.kickstarter.com/projects/1846577405/homebiogas-20-transforms-your-food-waste-into-clea
The problem with it being that outside temperature cant fall below 20° Celsius. So some parts in the world works fine, but most would only work for short time in summer. Also far cheaper and better cold protected if a simple hole in ground, one side on a slight slope so excess can run out as new stuff is put in. Food scraps work but cow manure is much better as long as acid and alkaline content are in right amounts. About 2 years ago was experimenting with small 30 liter drum.
They can use gas to heat up electric heater and use the electric heater to heat up the small room where the biogas is stored. - problem solved.