New battery turns sewage into electricity


U.S. scientists may have found a new way to produce clean energy by way of dirty water, according to a new study.

The engineers have developed a more efficient method to use microbes to harness electricity from wastewater.

They hope their technique can be used in wastewater treatment facilities and to break down organic pollutants in the “dead zones” of oceans and lakes where fertilizer runoff has depleted oxygen, suffocating marine life.

The team from Stanford University has started small, with a prototype about the size of a D-cell battery, consisting of two electrodes plunged into a bottle of wastewater filled with bacteria.

As the bacteria consume the organic material, the microbes cluster around the negative electrode, throwing off electrons, which are captured by the positive electrode. “We call it ‘fishing for electrons,’ ” said environmental engineer Craig Criddle, one of the lead authors of the study, published in the Proceedings of the National Academy of Sciences.

Scientists have long known of microbes that live in airless environments and are capable of “breathing” oxide minerals to generate energy. Several research groups have tried to turn these microbes into bio-generators, but it has proven difficult to harness this energy efficiently.

The researchers said their new model is simple and can harness about 30 percent of the potential energy in the wastewater — about the same rate as commercially available solar panels. The process has the added benefit of cleaning the water.