Cows at Fiscalini Farms in Modesto, California.
Three years ago, we visited a Central Valley dairy that was taking an innovative approach to its waste problem. Instead of collecting thousands of pounds of cow manure in open holding ponds, Joseph Gallo Farms uses it in a renewable energy technology known as a methane digester.
Methane gas is a natural byproduct of cow digestion. It's produced as bacteria inside their stomach break down food. That process continues on the back end (so to speak) as cow manure decomposes.
Methane is also a powerful contributor to climate change - about 21 times stronger than carbon dioxide. The UN has estimated that 18 percent of greenhouse gases worldwide come from livestock. (Check out this story from KQED's Climate Watch for more on the sources of methane.)
By capturing methane, dairy digesters keep it out of the atmosphere. But they also create a source of renewable energy. Methane is a natural gas -- it can be burned just like propane. So, Gallo Farms pipes the methane over to a generator, which produces enough electricity to run the farm and their cheese plant.
Since our visit, the story has taken an interesting turn. Both Gallo Farms and another dairy with a digest...