The digester pond is covered with an enormous tarp
Electricity from the Methane Digester powers Albert's electric car
The Straus farm with Methane Digester pond
Poop to power – renewable energy powers the Straus dairy using methane from our cows
We make electricity from manure, the manure from our own cows, to be precise. We create enough renewable energy to power the entire dairy, to charge Albert Straus’ electric car and to feed some electricity back into the grid. We use a methane digester, which turns methane gas, a part of manure, into electricity. Poop to power, so to speak - this is how it works.
How the methane digester works
Twice a day, the barns are flushed clean with recycled water, including water that has been recycled from the creamery. Manure from the barn is also scraped by tractor into a holding pond. From there, it goes through a separator, which separates solids from liquids. The solids are composted and the liquids are piped into a second pond that is covered with an enormous tarp. Under the tarp, the liquid manure is transformed by bacteria, through the process of anaerobic digestion. The result of this sustainable practice is renewable energy in the form of methane gas, carbon dioxide and a small amount of hydrogen sulfite.
The tarp that covers the pond captures the gas. It is then pumped to a combustion engine where it fuels a generator and creates electricity. The heat created in the process is used to heat water for the dairy. This 180-degree Fahrenheit water is used to clean barns.
There are many benefits to this system in addition to the energy it generates. The most important is that it prevents methane gas, a greenhouse gas that is 23 times more detrimental than carbon dioxide, from entering the atmosphere. In addition, it greatly eliminates odors on the farm and significantly reduces flies. Two byproducts, separated solids and leftover liquids, are used as organic fertilizer on pastures. The system allows the Straus dairy to run electrical meters in reverse and to offset electrical usage from other meters at the farm.
Good-to-know facts and numbers:
- Generator capacity: 80 kW
- Average performance per month: 28,800 kWh
- Average performance per day : 960 kWh
- Implementation cost: $334,680 – initial conversion to anaerobic digester plus refurbishment
- Initial funding: $155,261 – DPPP and EPA through CA Water Quality Board
- Annual cost savings: $40,000 - $50,000
- Return on investment: 4-5 years
Learn more about our other sustainable practices >>