Approximately 7 years ago, Crave Brothers Farmstead Cheese of Waterloo, Wisconsin, decided to “go green” and partnered with Clear Horizon of Milwaukee to build an anaerobic digestion system at the Crave Brothers farm. Crave Brothers thought the system would be a good way to generate green energy and eliminate methane gas at the same time.
The anaerobic digestion system works via two large 700,000 gallon enclosed tanks that hold the waste from the farm and cheese factory. The waste is heated to 105°, the ideal temperature for maximum microbial activity. One of the results of the microbial activity is methane gas, which is highly combustible. The methane gas powers the engine that turns the turbine, which in turn produces electricity. The waste is not being burned – just the gas. The digester runs about 98% of the time at 94% of capacity. It holds around 21 days of waste at a time.
When the solids come out of the tank, they are fully dried to use for livestock bedding, while the liquids are used to fertilize the fields that grow Crave Brothers’ cow feed. The fertilizer is of high quality and is very plant-friendly.
George Crave, President of Crave Brothers, said, “This system produces a better fertilizer and livestock bedding, and all with products we already have.”
While their electrical output is fairly constant, there is a little more produced during the summer. This works well, as the cooling fans and refrigeration system at the cheese factory have higher demands in summer. In general, Crave Brothers produces enough electricity to power the farm and cheese factory, plus over 300 additional homes in the area – the equivalent of powering 600 homes in total.
While there are great benefits to having this anaerobic digestion system, there are other considerations, as well. It was a large investment and the equipment requires maintenance. In addition, the digester needs to be run by a qualified engineer. This engineer has to regularly check the digestor and maintain the system to keep it running efficiently.
Crave Brothers is happy with the digester. George Crave says, “It’s a good system. It is one of the spokes in the wheel of becoming more energy independent.”
Crave Brothers Farmstead Cheese produces fresh mozzarella, mascarpone, farmer’s rope cheese, Les Frères®, Petit Frère®, and Petit Frère® with Truffles. For more information, please visit their website. If attending the ACS Conference, you can tour the Crave Brothers facility on Tour E: The Scenic Wisconsin Tour, on Wednesday, July 31st. For more details or to sign up for this tour, contact Jana Hemphill at the ACS office:720-328-2788.