Jason Koski/University Photography

Students from the civil engineering course Engineers for a Sustainable World helped bring a biomass heating system to Cayuga Nature Center. From left, Jason Thomason '10, Carolyn Evans '10, Patrick Donaldson '10 and Steve Castonguay '10 were on the team that built the wood chip storage shed, visible in the background.

Visitors to Ithaca's Cayuga Nature Center can step inside the lodge to warm up this winter knowing that its toasty heat is green, thanks in part to Cornell engineering students who helped plan, design and install a new biomass heating system that uses wood chips for fuel.

Over the past two fall semesters, students in the civil engineering course Engineers for a Sustainable World, taught by senior lecturer/research associate Francis Vanek '91 and visiting assistant professor Park Doing, have worked on different aspects of the Cayuga Nature Center biomass heater project. Students have been assigned everything from analyzing biomass energy efficiency and assessing how much fuel the Cayuga Nature Center's own woods could produce to building a shed to store the wood chips.

The students' project adviser was Tony Nekut '72, Ph.D. '78, a member of the Cayuga Nature Center advisory council and longtime activist for renewable energy sources.

The nature center's state-of-the-art, European-designed biomass boiler system, manufactured by the company ACTbioenergy in Schenectady, N.Y., has been operating since December. It is expected to save the nonprofit organization about $6,000 in heating costs per year, according to executive director Tom Trencansky.

"It's a tremendous resource," Trencansky said. "We were paying a fortune for propane."

The $200,000 project was funded in part by the New York State Energy Research and Development Authority, which in 2008 awarded a total of $2.5 million to projects statewide that would advance renewable energy systems. Cost to the nature center was minimal, Trencansky said.

The six students assigned to the biomass project in fall 2009 built the storage shed that houses the wood chips. The structure protects the precious fuel from the elements, as well as shelters two tractors that carry the wood chips to their destination.

Their job included demolishing the old shed, surveying the ground, digging holes for posts, leveling the soil and laying a concrete floor, explained Carolyn Evans '10, a civil engineering major.

"It was a lot bigger than we thought it would be initially," Evans said of the finished product. "It's more like a barn."

The students rotated afternoons and weekends at the nature center, supervised by Nekut, to build the shed. A contractor was hired to build a secondary unit to house the wood chip hopper, where the chips are fed into the heater unit.

"It was cool to have a class where we actually built something," said Patrick Donaldson '10, also civil engineering. "It wasn't just homework problems."

Vanek said the biomass technology faces some hurdles, in part due to the relative expense of the chips, and the work it takes to get the chips and store them. However, as the students showed in their analyses, the wood chips are cost-competitive with traditional fuels when energy conversion efficiency is considered.

Wood chips, the students calculated, are 76 percent more cost effective than natural gas; 80 percent more than home heating oil; 85 more than propane; and 79 percent more than wood pellets -- a different biomass source made of compressed sawdust and that is much more expensive than chips.

Trencansky said the nature center was looking into someday harvesting its own wood chip sources on its 100-acre property. But right now, buying the chips and promoting the technology fits squarely with the center's mission.

"We would like to grow and harvest our own biomass and burn it, and then we would have control from start to finish of our needs," he said.