Some of the best fossil fuel alternatives are not just renewable sources but also local and decentralized sources: Projects in California and Texas are capturing methane from local dairy farms to generate electricity for public use. Meanwhile, Rock Port, Missouri, is set to become the first U.S. city entirely powered by wind.
- Texas Biogas Plant Milks Benefits from Dairy Cow Manure
- California Commission Gives the Go-Ahead for Utility to Produce Electricity from Biogas
- Rock Port, Missouri, Will Be the First Wind-Powered City
Texas Biogas Plant Milks Benefits from Dairy Cow Manure
A manure-to-gas digester in Texas is creating methane from dairy cow manure. The plant not only produces a renewable fuel, it also creates fertilizer, reduces emissions of methane, and reduces pollution to the local watershed. Other "green" benefits include a healthy profit to Microgy, Inc., owner, and operator of the plant.
IMAGE: Digesting tanks at Microgy, Inc.'s biogas plant process manure from about 10,000 cows into methane and compost.
The facility is located on Huckabay Ridge, in Erath County, Texas, about 80 miles southwest of Forth Worth. The plant is adjacent to Producers Compost Incorporated (PCI), which receives cow manure and provides it to the Microgy facility. The facility includes eight, 916,000-gallon tanks that digest manure from up to 10,000 cows. The digesters produce methane and a nutrient-rich compost.
The methane is purified, compressed, and fed into a natural gas pipeline that carries it to Austin, Texas. There, the Lower Colorado River Authority uses the methane as fuel to produce electricity. The compost is sent back to PCI, which sells the product outside the local watershed.
Microgy, which is a subsidiary of Environmental Power in Portsmouth, New Hampshire, has invested $12 million in the Texas facility and expects it to produce 1 billion ft3 of methane per year. This production represents an energy content of 650 million British thermal units. The company expects to make a profit as long as natural gas prices are at least $4 per 1,000 ft3. Over the past year, prices have ranged from $5 to $7 per 1,000 ft3, making the plant's annual output worth at least $5 million.
Further revenue may come from renewable energy credits. Microgy expects the plant to generate offset credits for 200,000 tons of carbon annually. Those credits can be sold in the carbon trading market. On July 20 the Chicago Climate Exchange listed the price for one carbon credit for 1 metric ton of carbon dioxide at $3.50. At that price, the facility's offset credits would be worth $700,000 per year.
The environmental benefits to processing manure into fuel include cleaner air and water. Some dairies get rid of manure by sluicing it off to lagoons, which produce methane that escapes into the air. Methane has a global warming effect that is 21 times that of carbon dioxide, so using the methane for energy production significantly reduces greenhouse gas emissions. And because manure that is used in the biogas plant is not washed off land surfaces by rain and irrigation into local rivers and streams, the local watershed also benefits.
For the past 10 years, Erath County has struggled with elevated phosphorus and nitrogen levels in the soils from manure. The Huckabay Ridge facility holds the promise of reducing these chemicals to manageable levels.
Biofuels are just one part of a burgeoning renewable fuels industry in Texas. Already leading the nation in wind power generation, Texas is also taking advantage of other biomass and geothermal resources. According to a report by the University of Tennessee Department of Agricultural Economics, Texas will lead the nation in renewable fuel production and will reap a $22.8 billion boost to the economy in the process.
For more information, read Microgy's description of the biogas plant.
See more Texas project descriptions published in Conservation Update.
California Commission Gives the Go-Ahead for Utility to Produce Electricity from Biogas
Transforming a waste problem into a revenue stream
A California utility will soon begin using methane from dairy farms to produce electricity.
In late May, the California Public Utilities Commission (PUC) approved a contract between Pacific Gas and Electric Company (PG&E) in San Francisco and BioEnergy Solutions in Bakersfield to provide 8,000 million British thermal units (Btu) of methane from dairy farms in central California.
IMAGE: Manure from dairy farms can be processed to produce methane, creating a second source of income for the farmers.
Under the contract, BioEnergy Solutions will deliver up to 3 billion ft3 of methane per year, enough to produce electricity for about 50,000 homes in central and northern California.
The agreement will help PG&E meet the California renewable portfolio standard that requires investor-owned utilities to procure 20% of their power from renewable sources by 2010.
The idea for the project came from a third-generation dairyman, David Albers, who owns Vintage Dairy in Fresno County. He believes that producing a usable biogas — the term for methane produced from animal wastes — from anaerobic digestion can help transform an environmental problem for the state's 2,000 dairy farms into a source of revenue.
"It's really simple," Albers said. "All we are doing is capturing the gas that is produced by the breakdown of the manure. Really we are just collecting gas and providing a revenue stream for the dairies. And all of us win because there's a reduction of greenhouse gases."
Albers is also the founder and president of BioEnergy Solutions, the company that manufactures, installs, and can operate the digesters at dairies. Albers claims the company's digester reduces methane emissions by 70% compared with uncontrolled manure pits. The BioEnergy digesters also have lower emissions than those used to create on-site power for dairies and other manure handling operations.
In the Vintage Dairy project, manure is digested by bacteria at the bottom of a lagoon in a low-oxygen (anaerobic) environment. This decomposition produces methane that is trapped below a floating cover, then collected and piped into a cleaning system. The system compresses the methane and removes hydrogen sulfide and carbon dioxide. The methane is then tested for quality and injected into pipelines owned by PG&E, which combusts the methane to produce electricity.
Vintage Dairy has 3,000 cows. The American Society of Agricultural Engineering Standard says that one dairy cow weighing 1,000 pounds generates 10 pounds (dry weight) of volatile solids per day. Using that standard, Vintage Dairy cows could produce 30,000 pounds of manure per day. The dairy estimates its manure will produce about 190 million Btu of methane per day. Construction of the lagoon began in June and gas shipments to PG&E pipelines will begin as soon as next month.
Within the next two years, BioEnergy Solutions will expand to as many as 50 additional dairies in Fresno, Kern, Tulare, and Kings Counties to meet the terms of its contract with PG&E. The waste management company will provide digesters at its own expense and then share revenues from the sale of methane with the dairy owners.
See more California project descriptions published in Conservation Update.
Rock Port, Missouri, Will Be the First Wind-Powered City
The town of Rock Port, Missouri, says it will be the first wind-powered city in the United States when the Loess Hills Wind Farm starts producing energy later this year. The wind farm consists of four Suzlon 1.25-megawatt wind turbines and will produce enough electricity to supply all the power needs for this town of 1,395 people.
IMAGE: These wind turbines in Texas are similar to the ones being built at Loess Hills Wind Farm in Missouri.
The Wind Capital Group of St. Louis specializes in small-scale wind developments for communities in Missouri and the Midwest. It is managing construction, and John Deere Wind Energy in Kansas City is handling the financing. These two companies have already worked together on nearby wind farm called Cow Branch that is rated at 50 megawatts.
The Missouri Public Utility Alliance in Columbia will purchase excess electricity from Loess Hills when the output from the wind power plant exceeds consumption in the town. This alliance provides electricity to Rock Port Municipal Utilities, which distributes to customers in town. The wind farm is sized to provide enough electricity over the course of a typical year to match electricity consumption in the town.
For more information, see the John Deere Wind Energy
See more Missouri project descriptions published in Conservation Update.