Cornell plant scientists have invented a new method that uses manure and other farm byproducts to remove toxic hydrogen sulfide from biogas -- a renewable energy source derived from the breakdown of animal waste.

Hydrogen sulfide can combine with water to cause acid rain and to corrode engines. Its removal makes biogas a more viable alternative fuel source. The new method will be marketed under the name SulfaMaster.

"SulfaMaster has a very large potential application for distributed bioenergy production at small sites around the country," said Gary Harman, professor of plant biology at the New York State Agricultural Experiment Station in Geneva.

Harman and Terry Spittler, a retired analytical chemist at Cornell, own Terrenew, a small company at Cornell Agriculture and Food Technology Park in Geneva that will market the product. In addition, Terrenew markets two other products that also use agricultural waste to help clean up environmental contaminants, including oil spills and heavy metals, from water.

With more than 9 million dairy cows in the United States, each producing on average more than 120 pounds of manure daily, biogas is already a key energy source for many sustainable farms. It's created by anaerobic digestion -- a process by which microorganisms break down manure and other organic matter in the absence of oxygen. The resulting biogas contains high levels of methane and carbon dioxide, but also a small amount of hydrogen sulfide.

Most methods for hydrogen sulfide removal require expensive industrial scrubbers that are not feasible for smaller farms.

"In most cases, these methods are meant for oil refineries and are not suited to small-scale use," Harman said.

On the other hand, Terrenew's process uses manure as a major component of a special medium, which is placed in barrels. "The gas is then piped into the bottom of barrels, [and as it] passes through the medium, the hydrogen sulfide is removed," Harman explained. "The resulting clean methane (plus carbon dioxide) can then be used for energy."

Harman estimates that the SulfaMaster medium can be reused up to six times before it needs to be replenished in the biogas mixture.

The new product also has promise off the farm. Biogas is prevalent in sewage treatment plants and landfills, especially those that accept construction and demolition waste. These sites can capture cleaner biogas and use it to power their operations.

Terrenew, using partial funding from the New York State Energy Research and Development Authority, demonstrated the product last summer at El-Vi Farms in Phelps, N.Y., and found promising results. The company plans to run another test to remove hydrogen sulfide from a landfill before releasing SulfaMaster. Last month, the Cornell Center for Technology Enterprise and Commercialization filed a patent on the technology that will be licensed to Terrenew.

Marissa Fessenden '09 is a former intern with CALS Communications.