Electric power industry makes new connections

Electric power industry makes new connections

Goldstein, Jerome

Portland General Electric, Alliant Energy, Wisconsin Electric and Pennsylvania Power & Light are some utilities that are plugging into biogas.

DURING the past six months, editors of BioCycle, Journal of Composting and Organics Recycling, have been gathering detailed information on projects, systems and companies that are using feedstocks such as manure, food processing residuals and municipal solid waste to generate biogas – which can be converted to heat and electricity. Increasingly, we have come across electric utility companies that are making use of recovered methane in their electric grid systems.

For example, Portland General Electric (PGE) of Portland, Oregon has teamed up with Cal-Gon Farms of Salem, Oregon to construct an anaerobic digester system to produce methane gas for use by the utility. According to Jeff Cole, biogas program manager for PGE, the digester began loading in mid-December. Cole supplies this background information on the combination pilot project/R&D site:

PGE began investigating biogas opportunities as a green resource during the summer of 1999. Toward the end of 1999, the utility contacted the Oregon State University extension service and the Oregon Dairy Farmers Association to test market perceptions and to see how receptive dairy producers might be to a utility initiative developed around farm-based anaerobic digesters.

“As a pilot,” Cole continues, “we were looking for a moderate size dairy (Cal-Gon is permitted for 500 cows) at a site served by PGE. As an R&D project, we have made some design decisions and added some systems and features that might not be included in subsequent projects.

PGE is also working with Threemile Canyon Farm in Boardman, Oregon, where the digestion facility will consist of two complete reactors. PGE hopes to work with additional farms on biogas recovery projects and is currently in early stages of additional feasibility studies. “We are being cautious about moving forward too aggressively,” Cole notes. “We would like to evaluate both design and operating practices.”

When asked about PGE renewable energy development plans and long term goals for biogas energy production, Cole replies: “The regulation of green power programs in Oregon is changing. As of March, 2002, PGE will be required to bid all green power supply and marketing services. While we began our biogas initiative under a regulatory imperative, we would expand upon these first two projects based upon the commercial potential of biogas, not in response to regulatory demand.”

PGE is Oregon’s largest electric utility with more than 730,000 customers in the Portland, Salem and northern Willamette Valley region. According to a recent report in Dairy Today, the CalGon Farms digester will generate 100 kilowatts of power from up to 500 cows, enough for 65 homes. Effluent from the digester will be processed through a solids separator, with the solids to be composted for commercial nursery use. The remaining liquid will be pumped to the farm’s two existing lagoons and later used to fertilizer cropland.


According to an October, 2001 article in the Portland Oregonian, the digester at Cal-Gon is fairly low-tech, relying on the dairy herd and colonies of bacteria and other microorganism to do most of the work. Officials estimate the cost of a facility capable of handling manure from 500 cows to be about $300,000. Regarding costs of generating energy by burning biogas, estimates have ranged from 5.5 cents to six cents a kilowatt hour (competitive in the region with wind-generated energy) to nine cents a kilowatt hour. “With prices for natural gas and other fuels rising, and utilities interested in becoming partners with farmers,” noted the Oregonian article, “biogas is becoming a more realistic alternative.” According to a dairy specialist with Oregon State University, who supplied the pricing data, there are 98,000 dairy cattle in Oregon – enough potential energy to supply nearly 10,000 homes.

Adds a biochemical engineer with the U.S. Department of Energy’s National Renewable Energy Laboratory: “No one should expect biogas to become a dominant energy resource, akin to oil and coal. But as the nation works toward attaining a sustainable energy supply, power produced from biogas with be part of the mix.


With offices throughout the Midwest in places like Cedar Rapids, Iowa and Portage, Wisconsin, Alliant Energy has arranged biogas recovery projects with Iowa swine farms (Top Deck), Seneca Foods in Minnesota, and others. “Innovative On-Site Technology Puts You In Control” headlines an Alliant Energy brochure adding this information on its agricultural digester gas generation methods:

Gas produced by a digester can be used as fuel for an engine to power an electric generator; Excess heat may be utilized for process heating or refrigeration applications, while some may be recycled and marketed for fertilizer. These services are listed as being available from Alliant Energy:

Identify digester opportunities; Determine type of digester; and Develop preliminary costs. “After the preliminary work is complete,” sums up the brochure, “Alliant Energy will work with you to design and construct the digester and install the electric generator and associated equipment. You can own the power generated or we will own, operate and maintain the digester generator for you. It can also provide a backup supply of electricity to your operation.”


Since August, 2001, the Pennsylvania Power & Light Company (PPL Spectrum) has been making electricity from the biogas generated at the Allentown, Pennsylvania wastewater treatment plant. The plant’s biogas is collected from two primary digesters and one secondary digester. According to John Steckel of PPL Spectrum, “the bottom line is that the system is working and – as with any cutting edge project, we are tweaking the process to boost production and solve some problems with gas composition.” PPL is also involved with creating power from methane gas recovered at landfills.

The Allentown project is using microturbines manufactured by Capstone Turbine Corporation of Chatsworth, California. The 12 microturbines are each capable of converting biogas into 30 kW of electric power. The microturbines, explains Steckel, operate in a “grid connect mode,” that is, only when utility power is available. In an article in a trade journal, Water World, Steckel wrote that the 12 microturbines would use about 191,500 cubic feet of gas per day at full capacity. The system would be capable of producing hot water to meet about 96 percent of the plant’s thermal requirements. Designers expect heat output from the microturbines will exceed plant needs the vast majority of the time. Allentown’s use of Performance Contracting with PPL Spectrum provided the means to address such issues and allow the project to move forward.

Under the performance contract, PPL Spectrum will assume all performance risks to the new equipment and guarantee saving from the project. The reduction in utility costs provides money for the payment and net savings in the city’s operating budget.

Founded in 1988 by two engineers, Capstone Turbine Corporation received major investments from individuals associated with high-profile Silicone Valley computer companies. Applications of its microturbines are at a wide variety of sites – from landfills for methane recovery to a dairy waste processing plant in Japan. “In resource recovery operations,” sums up Capstone president and CEO Ake Almgren, “the microturbines enables conversion of biomass waste gases into electricity, using fuel that is otherwise wasted and essentially `free.”‘

As further indication of how gas use applications are steadily emerging, Kurt Roos – AgStar program manager – points out that one of the program’s partner farms, Colorado Pork, has a 50 kW Capstone microturbine operating on biogas generated from a 5,000 sow heated mixed digester. “This is the first farm-scale application of this kind,” Roos notes. A 120 kW reciprocating engine operates in series with this system.


As part of the grand opening of a manure-to-energy digester at Tinedale Farms in Wrightstown, Wisconsin in June, 2001, the president and CEO of Wisconsin Electric/Wisconsin Gas, Dick Grigg, delivered these remarks:

“I’ve helped design, construct and operate power plants in Wisconsin for more than 30 years, and this is definitely a first. This facility represents the creativity and innovation our state needs to care for our environment and secure our energy future.”

Added Carl Theunis of Tinedale Farms: “Farming and caring for the environment go hand in hand. I’m very proud that we’ve developed a way to turn our waste into renewable energy and protect the land for future generations. This project also demonstrates how important the link is between our urban and rural areas. The electricity we generate here on the farm will flow to businesses and people’s homes.” Tinedale Farms milks about 1,800 cows. The generating unit at Tinedale Farms produces 750 kW; enough to provide electricity for about 250 homes.

Ag Environmental Solutions, LLC owns and operates the manure digester facility, taking the manure from Tinedale Farms, processing it through the digester and generating electricity. The processed manure is returned to the farm. Wisconsin Electric/Wisconsin Gas purchases the renewable energy for distribution throughout its service area. This facility will capture about 300,000 cubic feet of methane gas each day, reducing the methane odor by more than 90 percent.

In Minnesota, East Central Energy (ECE) the state’s oldest customer owned electric cooperative – distributes energy to more than 40,000 homes, farms and businesses throughout East Central Minnesota.

ECE is a partner in a digester operation at the Dennis and Marsha Haubenschild 760-cow dairy farm in Princeton, Minnesota. According to published reports, for a period last winter, the dairy cows were earning the farm 40 cents a day from their milk and 30 cents a day from their electricity. Biogas captured in a digester tank generates 3,000 kW of electricity daily, enough to power the Haubenschild farm plus 78 average size homes. ECE pays the farm 7.25 cents per kW hour, the full retail rate. Farm sales of electricity average $900 per week.

Copyright J.G. Press Inc. Jan/Feb 2002

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