Energy From Pig Slurry Helps Fight Climate Change

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Associated Press Writer STERKSEL, Netherlands—The 2,700 pigs on the farm that John Horrevorts manages yield more than ham and bacon. A biogas plant makes enough electricity from their waste to run the farm and feeds extra wattage into the Dutch national grid.

He even gets bonus payments for reducing greenhouse gas emissions.

As the world struggles to reduce pollution causing climate change, attention has focused on the burning of fossil fuels in factories, power stations, and vehicles. But U.N. scientists says farming and forestry account for more than 30 percent of the greenhouse gases that are gradually heating the earth. Much of that pollution comes from cattle, sheep and pigs that belch or excrete methane, a heat-trapping gas more than 20 times as potent as carbon dioxide, the most common global warming gas.

Negotiators from 190 countries have been working to reach a new climate change agreement in December on ways to reduce emissions and help countries adapt to changes in climate. They will reconvene June 1 in Bonn, Germany, for another two-week session.

Yet it is uncertain whether cutting agricultural emissions will be part of the agreement expected to emerge at the final meetings in Copenhagen, Denmark. The subject is complex, emissions are difficult to measure, and the whole question is politically sensitive, touching on the distrust between the world's rich and poor countries.

Scientists say it is too important to be left out.

"It would be absolutely nuts to ignore agriculture and forestry in any future climate deal," said Pete Smith, professor of soils and global change at the University of Aberdeen in Scotland.

U.N. studies say agriculture is the main source of income for one of every three working people. It also is a growing source of pollution, as the global population increases and living standards rise in developing countries where more people are eating meat.

The latest research by the U.N.'s Food and Agriculture Organization says animal husbandry accounts for 18 percent of all greenhouse gases, when taking into account the grassland and forests that are cleared for raising livestock.

When the FAO report came out in 2006, "people in the livestock sector were shocked because they thought they did a good job," says Akke van der Zijpp, a professor of animal husbandry at Wageningen University, a premier Dutch technical facility. Now they "are becoming slowly aware that this problem has to be solved."

One way to deal with it is to reduce the methane animals produce by changing their diet or through breeding.

Another is to make use of it and burn it.

Horrevorts says Wageningen University's Praktijkcentrum, or Sterksel Research Center, creates 5,000 megawatts a year, enough to power 1,500 homes. The farm uses the electricity it needs and feeds the rest into the national grid, for which the government pays up to euro177 ($238) per megawatt as a green energy subsidy.

Pigs can be remarkably house-broken animals. Here, they drop their waste through slats on the floor in the middle of the barn while spending most of their time in open stalls to the side. The slurry is channeled into three 4,000 cubic meter (141,250 cubic feet) tanks, then mixed into a thick goo with other organic waste like low-quality grain and carrot juice to increase the methane potential. Bacteria break down the material in a digester tank and the gas is siphoned off into a generator to produce electricity.

Horrevorts says a group including his operation and four other commercial farms avoids methane emissions equivalent to 40,000 tons of carbon a year. Dozens of private or nonprofit companies known as offset providers will "buy" those tons as a way of supporting renewable energy or other projects that reduce carbon emissions, then resell the credits to individuals or companies who want to shrink their carbon footprint.

Last year, Horrevorts said, a British offset provider paid euro5 ($6.70) per ton for people wanting to neutralize plane travel or rock concert tickets. This year, the farm was negotiating with a Dutch company seeking to become carbon neutral to promote a green image.