Turn household wastes (human wastes and food scraps) into clean burning biogas with $300-$400? (waiting for current price list) Biotech biogas plants, or make one yourself. Biotech also sells waste to electricity plants. Payback period is only 2-3 years. They now mass produce their biogas plants out of PVC and aim to sell one to every household in India as a standard commodity.
“Getting rid of waste, both food and human, is essential to hygiene. But waste is also a cost-effective and sustainable source of fuel. The evidence? Well, since 2004 Biotech India has improved the lives of hundreds of thousands of people in Kerala, Southern India and saved several thousand tonnes per year of CO2 simply by getting rid of waste. [Way more now since these numbers are five years old and the company is booming and they’ve expanded to other states.]
Their success is all down to their biogas digester. Designed to be easily installed, it comes in different sizes to process not only home waste but also market and municipal waste. Digestion produces biogas which in turn reduces reliance on more expensive and harder to access LPG.”
This second video describes a related project that makes fertilizer.