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Royal Farms Operates Digester For Over 20 Years
| Location |
Tulare, California |
| Project Type |
Farm scale |
| Animal Type |
Swine (farrow-to-finish) |
| Population |
1,650 sows |
| Baseline System |
Anaerobic lagoon |
| Digester Type |
Covered lagoon |
| System Designer |
Sharp Energy |
| Biogas Use |
Cogeneration |
| Generating Capacity |
75 kW and 100 kW Waukesha |
| Receiving Utility |
Southern California Edison |
In 1972, Royal Farms started a waste management program to meet or exceed public health and environmental standards while supporting a large animal population in a confined area. To help meet this objective, they installed a 3-cell anaerobic lagoon to stabilize manure flushed from the hog barns. By the 1980s, the pork industry had become increasingly competitive and owner, Roy Sharp, began to investigate whether it was possible to generate electricity from the biogas as a way to reduce costs and increase profits.
In 1982, the farm covered only one-third of the primary digester cell, but captured enough biogas to power a 75 kW engine-generator set. The digester worked so well that by 1987 Mr. Sharp had expanded the cover by 30,000 ft2 to cover the entire primary cell and had also added a second engine-generator set.
Since then, recovered biogas has fueled two Waukesha engine-generator sets that generate electricity for all the farm's electricity needs with excess sold to the local utility. Heat is recovered from the engine generator and used as supplemental heat in the nursery barns. With regular oil changes, the engines provide 96 percent operating availability.
Royal Farms considers its anaerobic digester as part of a complete manure management system, which includes the following benefits:
- Reduced odors
- Recovered biogas generates enough electricity to offset 80-90 percent of the farm’s monthly energy bills
- Recovered heat produces hot water and reduces energy costs
- Stabilized effluent provides nutrients for corn, wheat, and silage crops
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