The energy often used for cooking, cooling and heating is gas. Most gas, like oil, is drilled from oilfields or gas fields. Another way to generate gas is a bit unique
In Java, Indonesia, people who had used firewood for cooking for a long time started using kerosene recently. But after the price of kerosene increased, some people in rural area had trouble getting enough 
fuel. Some had to collect firewood in the forests again. There was a concern that the forests would shrink due to tree cutting.
A village called Lembang of Java decided to use biogas instead of kerosene. Biogas is a gas generated from livestock manure or food waste through chemical reaction in the absence of oxygen. By processing livestock manure or food waste with bacteria in a closed container, a gas called methane is produced. Unlike the gases extracted from the oilfields underground, methane does not emit extra carbon dioxide (CO2) into the air when it is burned, which makes it an environmentally-friendly energy source.
In Lembang, people use plastic containers called "biodigester" (diameter 1m, length 7m). One biodigester can generate cooking gas for 1.5 families by processing about 100 kilograms of cow dung produced by one cow per week. In addition, as a byproduct, the biodigester produces about 10-20 kilograms of organic fertilizer per 100 kilograms of cow dung, which enables farmers to grow healthy vegetables without using chemical fertilizer.
By saving money for kerosene used for cooking and chemical fertilizers, more children who were once unable to go to school can receive education, and more sick people can afford adequate medical treatment. Livestock manure and food waste were mere wastes before, but now they are important sources of energy.Source: Miracle Report