The whole thing may sound like science fiction, but—for the sake of comparison—Germany has more than 6,000 units like this installed, providing power for more than 4.3 million homes. The U.S. has just over 200 operating farm scale digesters, most installed in cooperation with the dairy industry. That should change as part of the new methane initiative announced by President Obama in March. This summer a partnership of USDA, EPA, the Department of Energy, and dairy will release a biogas roadmap, outlining strategies to increase adoption of digester technology and a range of other improvements.
Dairy CAP research will help guide this work, though for now, admits Larson, “It is a data-gathering nightmare.” Analyzing manure means knowing where the feed comes from, the inputs into the feed, where and how the manure is processed and land applied, and even how much energy one particular manure pump uses. “You have to understand all the inputs and outputs to the entire dairy system in order to assess impacts and make informed recommendations,” she says.
But such detail yields more precise ideas about how to reduce emissions by helping target areas with the greatest potential. Larson is already working on digester additives that might increase gas production and decrease the levels of corrosive sulphur.
Feeding electricity back into the grid is a big financial obstacle, but new technologies may cut that step altogether. For example, biogas can be cleaned and compressed for use as vehicle fuel. Biogas can also be used to make plastic; one company is exploring a system to manufacture plastic from digester methane.
Larson calculates that if digesters processed waste from half of the 1.26 million dairy cows in Wisconsin, it would yield a 6 percent reduction in greenhouse gas from the agricultural sector. Other less capital-intensive processes could yield further reductions when combined with digestion.
“Although sometimes the numbers seem low, this is one piece of many that contribute to greenhouse gas emissions,” Larson says. “It will be critical as we move forward that we take advantages in all sectors to reduce our overall emissions.”
Working alongside climate scientists has opened her eyes to how critical it is to address climate change now—and how behind we really are. “Changes are coming,” she says. “We are on the verge of realizing significant impacts from climate change, if not past it.”