Dairy Digesters Have Struggled
A digester that can turn manure from dairy cattle into renewable fuel is not a new concept, but over the years very few have lasted. Daryl Maas of Maas Energy Works is a part of a collaboration in Tulare County California that have developed a model to make it work.
“Up until 10 years ago, even five years ago, a lot of digesters had struggled in California and elsewhere. They didn’t have a strong revenue model. They were often under capitalized or not maintained well. Just the technology was overly complex, but a covered lagoon in Tulare county California is about the simplest digester you can imagine,” said Maas.
These covered lagoons are located on site and over a dozen dairies and the biogas is connected to Calgren Renewable Fuels via pipeline.
“As a practical matter in California what we do is we build a large tarp, a gas tight tarp over a pond of manure,” said Maas. “So if you can imagine several acres of liquid manure sitting there, which is something we imagine all the time here, we love these topics. If you were to put a gas tight seal over the top of it, the bacteria in that manure, they think there’s still in a cow. They continue breaking down the little bits of calories and releasing methane gas, which we can capture. And then we’ve got a collection of biomethane, which is mostly methane gas, which is the same energy as natural gas.”