Pros & Cons of Using Human Waste As an Energy Source

Human waste may be a stinky alternative as a future energy source, but some believe it may be useful -- at least on a small scale. The concept could benefit the environment and foster energy independence, but it has drawbacks that scientists and governments will have to consider.

Provides Fuel for Cooking

• While it may not sound particularly appetizing, feces can be converted into methane gas for cooking. Wired.com reports that a Rwandan prison uses prisoners' feces to produce the gas, reducing wood-fuel costs by 60 percent and saving about $1 million. The prison uses beehive-shaped biogas facilities that are up to 1,000 cubic meters, where the feces ferments using bateria, releasing methane gas that's captured and used for fuel.

Pollution Reduction

• The conversion of feces into energy has the potential to reduce pollution in some areas. In the Rwandan prison example, overcrowding led to large amounts of human waste the prison couldn't process, so the waste was simply thrown down a hill into natural bodies of water, polluting them. The biogas facilities significantly reduced pollution.

Expensive Alternative

• Despite its benefits, biogas derived from human waste is still expensive on a small scale and not nearly as productive as traditional energy sources such as oil on a larger scale. For example, a one-cubic-meter digester can provide a four-person family in India with gas for cooking all their meals as well as with fertilizer, but it costs about $425. The manufacturer argues that it will eventually pay for itself, but the up-front price is cost-prohibitive for most Indians.

Inefficient System

• Since direct burning of biomass releases greenhouse gasses such as carbon dioxide, it must be converted into methane, an expensive process. It costs a lot more to accumulate and harvest human waste energy than it does to extract fossil fuels. In addition, the power plants required to process the fuel would take up a lot of space, and the conversion process requires large quantities of water.