Duke, Google turn hog waste into clean energy

David Zucchino, Los Angeles Times

Monday, December 26, 2011

Yadkinville, N.C. -- Loyd Bryant used to pump manure from his 8,640 hogs into a fetid lagoon, where it raised an unholy stink and released methane and ammonia into the air. The tons of manure excreted daily couldn't be used as fertilizer because of high nitrogen content.

The solution to Bryant's hog waste problem was right under his nose - in the manure itself.

A new waste-processing system - essentially a small power plant - installed on his 154-acre farm uses bacteria to digest the waste and burns methane to produce electricity. It also converts toxic ammonia into forms of nitrogen that can be used as fertilizer for more profitable crops.

Waste-to-energy systems have been around for at least 15 years. But Duke University, which helped develop and pay for Bryant's system, says this one is the cleanest in existence - and virtually the only one that tackles all of the environmental problems created by animal waste.

Simple process

The system was built with off-the-shelf parts and simple design plans that are free for the asking. It's poised to become the standard for a cleaner waste-to-energy model that brings together farmers, utilities and private companies in an environmentally friendly effort.

"It does it in a way that is not overly complicated and stands to yield many more benefits beyond energy production and environmental protection," said Tatjana Vujic, director of Duke University's Carbon Offsets Initiative.

The $1.2 million project is funded by the university, Duke Energy and Google, which operates a data center in nearby Lenoir, N.C. All three, along with Bryant, will benefit.

Bryant saves money on electricity and gets a cleaner farm. Improved air quality in his hog barns also means his pigs will have lower mortality rates and convert feed more efficiently, fattening Bryant's profits.

Duke University and Google earn carbon offset credits from the system. Duke Energy gets renewable energy credits in a state where a new law requires utilities to produce a small percentage of electricity from renewable resources beginning next year. North Carolina is the only state that will require a portion of that set-aside to include electricity produced from hog waste.

Vast amounts of energy

Bryant, whose family has farmed the rolling Piedmont of central North Carolina for four generations, says the 65-kilowatt turbine generates enough electricity to power the system - and five of Bryant's nine hog barns, where giant fans hum day and night. The digester captures methane equivalent to 5,000 metric tons of carbon dioxide per year and produces enough electricity to power 35 homes a year.

The Duke system is pioneering, said Gary Gero, president of Climate Action Reserve in Los Angeles, a nonprofit group that runs the nation's largest carbon-offset registry and that developed the protocols that register and verify carbon offsets on Bryant's farm.

The number of waste-to-energy systems nationally is growing every year, according to the Environmental Protection Agency. Last year, 162 digester systems on U.S. farms produced 435 million kilowatt-hours of electricity - enough to power 25,000 homes for a year.

If 8,200 eligible dairy and hog farms nationwide used the systems, the EPA estimates, they could generate enough electricity to power 980,000 homes for a year. They would create the equivalent of removing 6.7 million cars from the roads by reducing methane emissions and avoiding power plant carbon dioxide emissions.

This article appeared on page A - 16 of the San Francisco Chronicle