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While it’s not exactly New York, New York, making it in a challenging environment is arecurring theme for a startup biogas facility in South Carolina that aims to eventually replicate itself in other, more lucrative green energy markets across the U.S.
BioEnergy Technologies began operating its GenEarth facility in 2013 outside of Charleston, S.C. as a facility that accepts wastewater sludge from municipal wastewater treatment plants, waste byproducts from chicken processors, grease trap waste and other organic wastes to produce methane rich biogas.
The biogas powers a combined heat-power unit (CHP) that includes a Cat® G3520C generator set and a heat recovery boiler in a containerized setup configured by the local CAT dealer, Blanchard Energy.
The CHP produces up to 1.6 MW of electricity, which is enough to power the equivalent of approximately 1,000 homes. The power is sold for distribution on the electric grid operated by the area utility, Santee Cooper, which gives customers the option of purchasing green power blocks on their monthly electric bill. The CHP’s heat-recovery boiler captures thermal energy from the generators’ exhaust. A portion of this heat is used for the anaerobic digester process. As a measure of future potential, the CHP can provide electricity and thermal energy at 80 percent efficiency based on fuel consumption.
“South Carolina has low power costs, with low landfill tipping rates and low disposal costs of the materials we use,” says John Halbig, vice president for Thompson Construction Group, the majority owner of the project. “We figure that if we can make this project work here, we can make it work anywhere in the states, particularly in the Northeast and the Northwest, where there are higher rates for green power and waste disposal which combine to provide a much greater opportunity for the economic success of a project such as this.”
The idea for the biogas plant originated four years ago with Greg Thompson, the CEO of Thompson Construction Group in Sumter, S.C., who viewed entry into the green power business as the right thing to do. “He saw it as an opportunity for Thompson Construction Group to develop expertise that would lead to more construction projects down the road and for us to be properly positioned to take advantage of this market as it matures,” Halbig says. “He was willing to invest significant resources in anticipation of a developing market.”
The GenEarth facility accepts an average of 100,000 pounds of organic waste per day. Wastewater sludge from the Berkeley County and Charleston Plum Island wastewater treatment plants is trucked to the facility in Moncks Corner, S.C., and fed into a mix tank along with waste material derived from poultry processing plants and other organic wastes.
Together with grease trap waste, the mixture of substrates goes into a 1.2-million-gallon anaerobic digester tank, where it’s broken down by microorganisms. From there, the substrates move to an adjacent post- digester, which further breaks down the material and yields a methane-rich biogas.
Together, the two digesters feed methane into the generator at a rate of 660 cubic meters per hour. Before the methane reaches the CHP, moisture is removed by first cooling the biogas to condense the moisture, and then running the biogas through a gravel filter to remove condensation.
Exhaust heat from the CHP is captured to create hot water utilizing a boiler mounted atop the containerized enclosure. The hot water is used to keep the anaerobic digesters heated at just over 100° F, which is necessary for the microbial bugs to produce methane.
After some tweaking six months ago by technicians Blanchard Energy, the generator is now running close to full capacity, 24/7.getting the CHP over the hump. Since then, we have seen some big gains in production.”
Adds J.R. McKenzie, maintenance manager for the facility: “Caterpillar is a very reliable, established name. Having operated the CHP for over a year now, I am very pleased with it. And Blanchard did a great job troubleshooting, and making some good suggestions about what direction we needed to go with the operation of our genset.”
Those technical adjustments resulted in CHP achieving a 96 percent capacity factor in October. This means the Cat G3520C produced 96 percent of the total possible energy should it have run a full capacity without stop the entire month of October. A good deal of the four percent reduction was tied to planned maintenance activity.
“Blanchard has supported us every step of the way, from bringing the heat recovery system online, to making several adjustments to the air intake unit,” Halbig says.
The selection of the Cat G3520C generator set was driven by the fact that it’s a high-efficiency engine, and the heat can be utilized as part of the CHP system, Halbig says. Caterpillar’s extensive dealer parts and service network also influenced Thompson Construction’s decision.
“We knew that if we needed service, that help from Blanchard was right down the street from us in Summerville,” Halbig says. “It’s important to have parts and service support readily available wherever future projects take us.”
Blanchard technicians provide preventive maintenance at 1,100- hour intervals, which includes valve adjustments and oil changes.
McKenzie uses diagnostic software, Caterpillar Electronic Technician (Cat ET), to monitor performance and identify any issues with the generator. When connected to an Electronic Control Module (ECM), a technician has the ability to diagnose existing and potential problems, configure the product, and obtain data for analysis.
“If you have a failure, you can go into the computer and determine what sensor caused the failure,” McKenzie says. “During the startup phase, it proved to be very beneficial.”
With eight employees, GenEarth is steadily growing in its knowledge of how to operate an anaerobic digester biogas plant, says Greiner, who came on board in June.
“A lot of folks, myself included, were new to this,” Greiner says. “This year, we have grown and experienced success by sharing knowledge with others who are familiar with this type of operation. We have seen some good gains in overall productivity and efficiencies, and a big part of that is how effectively we’ve been able to utilize our Cat equipment.
This story is reprinted with permission from RunReady Magazine.