The solid, residential and industrial waste landfill site, located near the town of Antioch in Lake County, was the area's dumping grounds from 1963 to 1984. During that time, its 51 acres were the receiving point for an estimated 2 million tons of waste. After the site's closing, few thought anything positive would come from heaps of rubbish. For years it sat dormant, allowing the waste to yield considerable amounts of gas. Decomposition in the landfill created methane and carbon dioxide. Both are greenhouse gases also known as “biogas.”
In 1998, the Environmental Protection Agency (EPA) issued a Record of Decision (ROD) requiring that the landfill go through closure. That required a landfill gas and leachate management system as well as landfill cover. In 2001, the EPA monitored gas flow rates, which propelled the concept of using those gases as an energy source.
This was where the Continental Electric Construction Co., Naperville, Ill., stepped in. Continental was to design and establish connections between the cogeneration system and Commonwealth Edison (ComEd), the Exelon-owned local utility provider, within the utility's regulations. The electrical contractor was responsible for ensuring the proper connections from the turbines to the utility, as well as ensuring safety based on ComEd's protocol.
In 2002, environmental engineering and consulting firm RMT Inc. took charge of the project. To begin, RMT completed and submitted a grant application to the Illinois Department of Commerce and Community Affairs. The state agency then awarded Antioch Community High School a $550,000 grant from Illinois's Renewable Energy Resource Program (RERP) to design and construct the facility. The Antioch School District raised $1.9 million by issuing a revenue bond.
First of its kind, the energy system design included an assortment of unique challenges. While cogeneration projects are becoming more common, none are like this. Beyond the efforts of meeting local utility requirements, RMT also needed to resolve easement issues, connect to the school's existing and still active heating system, cross railroads, and meet the EPA operational requirements.
Part of the challenge was to assemble the necessary pieces and players to make this energy source work. That included finding someone to do piping installation and to add the compression and cooling unit and 12 microturbines at the school site, said Mark Torresani of RMT.
Unison Solutions, an Iowa energy services provider that specializes in green energy, designed the cogeneration concept, from the landfill pipe to the pre-engineered building that houses the 12 turbines, said Jan Scott, Unison co-owner and president.
Unison created the sequence of operation for controls and automation as well as the turbines, which were supplied by Alliant Energy. Using the Unison plans, Continental designed and built the switchgears and breakers-work that included turbine operation and measurement of temperature and the pressure of the system.
For the control panel and related components, Continental subcontracted to Johnson Controls System. The school's control system was built by Johnson Controls. The system now established through the microturbines would be integrated with the existing system so that all operational information could be accessed at a central point within the high school, said Continental project manager Jeffrey Arnesen.
Unison built the 360 kilowatt (kW) microturbine plant for the high school, where 12 Capstone model 330 microturbines are housed in a small building in the school parking lot. Connected to them are two Cain heat exchangers that recycle the exhaust heat from the turbines. On average, the cogeneration system collects 325 standard cubic feet per minute of gas from the Antioch landfill. Because the gas emissions fluctuate, the system was designed to not take 100 percent of gas released on any given day. The supplemental gas is burned off.
Mike Hanek, Continental director of engineering, said his company's role was to help the project coordinators navigate the often complicated utility codes and set up an understanding with ComEd. Because it was a cogeneration project, there were multiple layers of regulations and requirements. As with most utility companies, codes were stringent and there was some initial skepticism about the project.
“This was a true design-build project,” Hanek said.
While Unison installed the 12 microturbines, Continental worked out the interface between the radial feed from the utility and the cogeneration plant. ComEd then came to complete a series of protection relay tests and to test the installation. A meter reads power generation and measures how much power is sent back to the grid as supplemental power when school was not in session.
Continental also provided the power connection for the landfill site's compressor building where the gases were pumped from under the fields and transformed into a liquid state.
Hanek said it is hoped that several more microturbines will be eventually installed at the landfill site, which would be fueled by the landfill gases and would power the pumps that pull the gases out of the ground. As it stands now, not all gases are used in the high school power generation system, so some are flared off at the site.
For the most part, Continental was able to let others deal with the more challenging mechanics of the project.
“This was a mechanical job,” Hanek said. “Our part went smoothly.”
The biggest challenge, he said, was working with utility representatives to ensure they understood what was happening at the site. For example, while the project was underway, the utility company wanted the main breaker open, something Hanek could not accomplish with the microturbine operation.
“We worked closely with them from the beginning,” said Ernesto Duran, ComEd spokesman on their relationship with contractors. “We feel it's a very important way to contribute to the development of alternative energy.”
According to Duran, Antioch Community High School during a typical summer month will be able to resell $2,000 worth of energy in addition to fueling the facility in its entirety.
“This has helped the school reduce energy costs twofold,” Duran said, “By selling us the excess energy and by saving in the [energy they use].”
Each microturbine provides 30 kWs of power. Together the microturbines produce enough electricity to power about 120 homes. The entire cogeneration plant still provides only a percentage of the power used during peak hours, when the 262,000-square-foot school requires about one megawatt. However, during off-school hours, the microturbines create more power than needed. Excess power is then sold to the public utility ComEd for use throughout the power grid.
In addition, the plant uses waste heat for the school. Each microturbine, about the shape and size of a refrigerator, creates enough waste heat to equate to 290,000 BTU per hour at 550°F.
The exhaust heat is routed through a waste recovery system into the school's boiler. This heat then fuels the hot water system for the school. When school is not in session, it is possible to route the heat generated from the turbines to neighboring businesses and industries.
By using this system, which was tested in the 2003-2004 school year, the school district expects to save $100,000 per year.
The landfill has been covered with turf and acts as high school baseball and soccer field. The energy recovered from the landfill is expected to last 20 years. The planned schedule states that as the amount of landfill gas decreases over time, the turbines will be taken offline. Another option is that natural gas could be used to supplement the landfill gas.
The school has worked several educational curricula around the system to teach kids about alternative power and technology.
“Really, a lot of people won in this deal,” Scott said. “It's helping the students, helping the environment and helping the taxpayer.”
Some awards that resulted from the project were the National Honor Award to RMT from the American Council of Engineering Companies (ACEC) for its innovative landfill gas-to-energy project with Antioch Community High School and the HOD landfill. RMT also received the ACEC-Wisconsin's Grand Award to RMT. The project also won the EPA Project of the Year award in 2003.
Teamed with Unison, Continental Electric is looking for additional markets for this kind of alternative power installation. The project initially intended the system to pay for itself within seven to eight years, it is now expected to be sooner than that.
“We hope this provides an encouraging example that other institutions can follow,” Duran said. EC
SWEDBERG is a freelance writer based in western Washington. She can be reached at firstname.lastname@example.org.