Cash from Trash

Turning trash into cash is probably the most environment-friendly profitable production in the world. Silently, the recycle industry has been deriving increasing amounts of methane from the trash we throw away (See National Geographic, January 2014).

Methane (CH4) is found in natural gas that is burned to generate energy. It is less dirty than oil or coal. It is formed from the decomposition of organic materials in the garbage. In the United States, the amounts of methane derived from all existing garbage landfills total nearly 4,000 megawatts (MW) of energy, enough to power roughly one million homes. This compares with wind (60,000 MW) and solar (7,500 MW).

At present, there are about 600 energy projects near the landfills across the country to feed on the methane from trash. Wells are constructed into the ground to pipe the methane to the surface for fuel. California has 75 of such projects, the largest number.

Typically in a landfill, the trash collected is sorted first to separate the recyclable materials for extra revenue generation. The garbage heap is reduced after the sorting and dumped into a large grave for natural decomposition. Steel-wheeled vehicles are used to spread and compact the garbage. The bottom and sides of the grave are layered with clay, rubber and plastic materials to prevent leakage into underground aquifers. The top of the grave is capped off with layers of clay, a drainage layer, topsoil and vegetation to prevent methane gases from escaping due to natural erosion and flooding.

January 2014