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Huckabay Ridge

Location Stephenville, Texas
Project Type Centralized/Regional
Animal Type Dairy
Population Feeding Digester 10,000
Baseline System Storage Stack
Digester Type Complete Mix
Co-Digestion Grease and other restaurant waste
System Designer Microgy (Environmental Power Corp.) (Original Developer/Owner); EM Biogas (Current Developer Owner)
Biogas Generation 2,739,726 ft3/day
Biogas Use Pipeline Gas
Receiving Utility Lower Colorado River Authority (through Sept 2008); Pacific Gas and Electric (Beginning Oct 2008); Alcor Energy is getting the thermal energy

Aerial view of centralized digester site

Photo: Environmental Power Corporation

In January 2008, a centralized digester developed by Environmental Power Corporation reached full-capacity production levels of pipeline-quality natural gas. The large-scale facility receives manure from multiple farms in the region, digests the manure in controlled and monitored complete mix digesters, and purifies the resulting gas to pipeline quality. Manure solids are separated and composted on site.

Each day, farmers unload about 10 trucks of manure, paying only for transportation. The facility adds water to achieve a solids content of 8-10 percent before the manure enters one of eight 900,000 gallon digesters. Computer controls monitor the digester's chemistry and temperature (120°F to 150°F). Fats, oils, and grease collected from restaurants are added to enhance biogas production.

The project includes the following benefits:

  • Helps farmers manage manure off site
  • Reduces odor
  • Generates solids for compost and liquids for fertilizer
  • Reduces impacts to the Bosque River Watershed
  • Creates marketable carbon offset credits

Huckabay Ridge is expected to produce approximately 650,000 MMBtu of gas per year—the energy equivalent of over 4.6 million gallons of heating oil. The Lower Colorado River Authority agreed to buy up to 2,000 MMBtu per day through September 2008. Environmental Power then has a 10-year contract to sell up to 8,000 MMBtu per day to PG&E in California .

Not only have we validated our technology, we have developed many innovative best practices and have gained valuable operating experience. We are applying this enhanced operating knowledge to the other large-scale biogas projects we have under development.
—Rich Kessel, President and Chief Executive Officer of Environmental Power, quoted in an Environmental Power press release

Project Update:In 2010, the facility was purchased by EM Biogas, a subsidiary of Elemental Markets. The digesters operated throughout the ownership transition and now process about 12,500 tons of manure and 14,600,000 gallons of substrate annually.

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