Most school administrators would view a neighboring landfill as little more than an unfortunate eyesore. But Bill Ahlers, the business manager for Community High School District 117 in Antioch, Ill., saw opportunity in the H.O.D. landfill located across the road from Antioch Community High School.
Ahlers’ idea — use gas produced in the landfill to generate electricity and heat for the high school, cut utility costs and provide practical educational experiences for students. He came up with the idea after reading a news report about the 51-acre landfill that had stopped accepting trash in 1984. Landfills typically require monitoring and care for decades after they are filled up. After 20 years of clean up work, the Environmental Protection Agency (EPA) and the landfill owner, Houston-based Waste Management Inc. were making plans for the final closure of the facility.
A key element of the closure plan involved the management of landfill gas, which is produced by decaying organic materials strewn throughout a landfill. The H.O.D. site produces about 300 cu. ft. of gas per minute (cfm), a production rate expected to last for 15 to 20 years. Under the closure plan, Waste Management would install a network of pipes to collect the gas, which would then be flared or burned, an environmentally acceptable disposal procedure used by most landfills.
May Antioch Have Your Landfill Gas?
When the EPA asked for public comments on the final closure plan, Ahlers’ dashed off a letter asking if it would be possible for the school to use the methane to generate electricity and heat for the school.
The letter prompted a visit from representatives of Waste Management and RMT, Inc., an energy management firm based in Madison, Wis. Ahlers’ idea was not only practical, it was being done all over the country under an EPA initiative called the Landfill Methane Outreach Program (LMOP).
According to Chris Voell, the EPA’s program manager for LMOP, more than 360 installations around the country now burn landfill gas to produce electricity that is sold to utilities or used to provide power to offices, manufacturing plants and other kinds of facilities.The LMOP program has seen very promising project development over the past few years, says Voell.
Despite the growing interest in the uses of landfill gas, only a couple of K-12 schools have explored these ideas, and no school has developed a plan as comprehensive as Antioch’s.
After talking to Waste Management and RMT, Ahlers asked for a study describing how Antioch could tap the landfill gas supply at H.O.D. Waste Management and RMT responded with a plan that would cost approximately $1.9 million, pay for itself over the course of 20 years and provide substantial savings in the form of reduced energy costs.
Go Ahead, Use The Gas
The district gave the plan a green light, and Ahlers set out to raise money for the project. He applied for a grant from the Illinois Department of Commerce and Economic Development that brought in $550,000. The district chipped in the rest by issuing $1.2 million in bonds.
While raising the money, Ahlers also negotiated two agreements with Waste Management. First, he worked out a contract under which the district would purchase all the methane gas produced by the landfill. Waste Management’s price: $1. Second, Waste Management agreed to lease 30 acres of the landfill itself to Antioch for 99 years. A second part of the project will involve turning the site into athletic fields, notes Ahlers. Waste Management charged $1 for the 99-year lease.They essentially gave us the gas and the land, Ahlers says.
Collecting And Cleaning The Gas
Mark Torresani, project manager with RMT, managed the design and construction of the Antioch gas-to-energy system, which includes components at the landfill and on the school grounds.
At the landfill, RMT constructed a small building that contains a compressor and a super chiller designed to prepare the gas for use in an energy system. First, the gas flows into the compressor, which compresses it to 95 pounds per sq. in., about the pressure of a bicycle tire. The micro-turbines require this level of pressure in the fuel they burn. After compression, the gas flows into the super chiller, which dries it and removes impurities.
Next RMT constructed a pipeline to move the gas from the landfill to the school grounds. The one-half mile line travels underneath a road and feeds into another new building constructed by RMT about 100 feet from the main high school structure. The building houses 12 micro-turbines manufactured by the Capstone Turbine Corporation of Chatsworth, Calif. The turbines produce a total of 360 kw of electricity from the 300 cfm flow of H.O.D. landfill gas.
The school uses about half of the electricity produced to power its own operations. The remaining electricity is sold to Commonwealth Edison, the regional utility company.
In addition, the turbine operation produces heat. RMT installed a heat exchanger that collects heat energy from the micro-turbine exhaust. This energy in turn heats waterin two of the school’s four hot water boilers. The existing natural gas system remains in the school in case a winter cold snap requires additional heat.
The 12 micro-turbines form a unique component in the design of the system. According to Torresani, the 300 CFM of gas supplied by the landfill is considered too small for most applications for two reasons. First, large industrial applications require much more gas than H.O.D. generates to satisfy their energy requirements. Second, landfill gas, like all energy sources, is finite. Over time, as the landfill produces gas and the school burns it, the gas flow from the landfill will decline. Turbines of different sizes require minimum gas flows to generate electricity. One Capstone micro-turbine, for example, uses 12 to 16 cfm to produce 30 kw of electricity. Together the 12 micro-turbines generate 360 kw.
In 10 to 15 years, when the flow of gas declines by 12 to 16 cfm, a micro-turbine can be disconnected from the system, and the school will continue to use and sell the remaining 330 kw of electricity that the system will then produce. When the gas flow drops again, another micro-turbine will be disconnected, and so on.
We’ll eventually produce less power with this system, but we’ll still be able to produce some power, Torresani says. That’s the advantage of many small engines compared to one large engine.
The economics of the energy system promise three financial benefits to the school district. According to Ahlers, the school will realize savings on electricity that it no longer has to buy from Commonwealth Edison. Additional savings will stem from revenues generated by the sale of excess electricity to the utility. Finally, the school will save money by replacing natural gas, which it must purchase, with landfill gas, which it has already purchased for a dollar.
When everything is said and done, the combined savings will pay off the bonds issued to pay for the construction of the system and generate about $100,000 per year in savings for the first ten years and somewhat less over the next ten years. Over the 20 year life of the project, we anticipate a net savings of approximately $1.5 million over and above the cost of the system, Ahlers says.
With this project we can lead by showing, continues Ahlers. In classes, we tell students that they need to be environmentally conscious. By putting landfill gas to use, we can show them that we’re doing our part.
Antioch’s curriculum coordinators are also working the landfill gas system into course work as well. The Physics Department is developing a study unit in which students will measure actual data from the system and use it to calculate heat conversion factors. The Chemistry Department plans to use the process to illustrate how an engine tears methane down into component chemicals to produce energy.
Taking A Prize
The project impressed the EPA so much that it named the Antioch installation LMOP Project of the Year in 2003. Antioch shares that honor with the BMW manufacturing facility in South Carolina, which has also installed a landfill gas-to-energy system to generate electricity and hot water. Through the efforts of the Antioch
Community High School, Waste Management, the State of Illinois, and RMT, a liability has truly been turned into an asset, says the EPA’s Voell about the Antioch award. Not only has this project turned a former landfill into a source of renewable energy, this project serves as a great learning tool for the students and the community.
Is landfill gas-to-energy an idea other school districts ought to consider?
I don’t think many schools are located next to old landfills, Ahlers says. Antioch, it seems, is one of the lucky ones.