By Becky Beyers
Morris, Minn.—Stand at the top of the hill under these wind turbines and you can hear the wind whistling across the prairie, all the way from Saskatchewan or perhaps points north.
It’s the sound of opportunity.
Researchers at the West Central Research and Outreach Center are ready to launch continuous operation of a process that takes the energy from these prairie winds, converts it to hydrogen and then to ammonia that can be used as fertilizer on the surrounding crop fields. The processing plant is part of the center’s larger efforts to reduce fossil-fuel consumption in agriculture over the next five to 10 years, says Mike Reese, director of renewable energy research at the center and leader of the project. As far as anyone knows, it’s the only plant of its kind in the world.
Photos by David Hansen
Making fertilizer from wind has been on the center’s agenda since before 2005, when the first 1.65-megawatt wind turbine went up. Today it provides more than half the electricity to the nearby University of Minnesota-Morris campus and has become a visual symbol of the university’s interest in sustainable energy. A few years later, a companion facility was built that converts wind into hydrogen. In the past few months, the final pieces to the puzzle were locked in with the installation of equipment that takes nitrogen from the air, combines it with hydrogen from the plant and makes anhydrous ammonia that can be used to fertilize farm fields.
The process takes place in two sheds marked “ammonia production room” and “hydrogen production room” that sit a few feet apart in a fenced-in area near the wind turbine. Inside the ammonia room, a complicated series of pipes and gauges connect to a tall pressurized reactor where the chemical conversion takes place. It’s called an ammonia production skid because it sits on runners that could be pulled out of the building for upgrading technology or maintenance, if needed.
The pipes bring in hydrogen and nitrogen under high pressure, mix the gases, preheat them to 800 degrees Fahrenheit and then send them into a reactor, pass the gases through an iron-based catalyst to create ammonia gas, which is then cooled to become liquid anhydrous ammonia. The pipes then take the ammonia back out and into waiting storage tanks, and residual hydrogen and nitrogen are recycled through the system. Sensors continuously monitor heat, pressure and other factors and can be read inside the building or from the team’s offices.
Asked how the team learned to run the equipment because it’s one of a kind, researcher Cory Marquardt, who manages operations, grins a little sheepishly. “A lot of trial and error,” he says.
“The idea is that one of these could run with three or four people trained,” perhaps producing enough fertilizer for a group of farms or a small-town cooperative, Reese says. This year, the center will produce about 25 tons of fertilizer and sell to farmers via Morris area co-ops; that’s a tiny portion of what the local farmers need, but it provides an alternative that may grow over time.
Whether similar facilities would be economically viable in the short term remains to be seen, Reese says, because the energy market is so volatile and agriculture production costs are currently high.
The project also considers the larger economic and environmental costs of the system. Scientist Joel Tallaksen (’93–B.S., ’02–Ph.D., plant biological sciences) is using life-cycle analysis models to evaluate exactly how much fossil fuel can be saved by using the new system as well as the costs of energy inputs and the net carbon balance once the equipment is running continuously.
Economics are part of the puzzle, Reese says, but consumers’ opinions also will play a role in whether the process catches on. “It’s kind of like the swine industry, where consumers are driving change in production,” he says. “Consumer demand eventually will drive us toward greener fertilizers.”
The team’s efforts are gaining worldwide attention; scientists from the World Wildlife Fund have visited to see the plant, as have colleagues from the Swedish University of Agricultural Sciences. Wind power is used in Sweden for electricity but hasn’t been used as an alternative to petroleum-based products, says Serina Ahlgren, a researcher who spent a week in Morris this January, but “interest is very high. Things are happening here.”
The center’s renewable energy work goes well beyond the fertilizer project. Research projects are under way that could find new ways to store large quantities of wind energy for non-windy days; to create fertilizers from other processes such as using non-thermal plasma; or to create other kinds of fertilizer beyond anhydrous ammonia. Reese and his team are working with faculty from several colleges and institutes across the university.
The hydrogen created from wind also is being used as a test fuel in two Workman utility vehicles that were donated to the center by Toro Co. The vehicles can run on electricity or hydrogen or, possibly, ammonia. The company tried them out at a New York state facility, but discovered limitations on hydrogen availability. So the vehicles were donated to the center for further research.
When renewable energy scientist Eric Buchanan fires up one of the vehicles on a cold winter day, it sounds like a small jet pressurizing before takeoff, until he puts it in gear. Then it’s silent and emits no smoke or fumes—just what a groundskeeping crew on a golf course or a farmer going out to check a field might want for early-morning maintenance. “We’re in the very beginning stages of deciding what we can do with them,” Buchanan says, but this summer the alternative fuels will be tested and evaluated for efficiency and economy.
“It’s definitely a viable technology,” Reese says of the utility vehicles. “It may be three or four years down the road, though, and that’s a long time for a company (like Toro) to wait. But we have the infrastructure here to really take advantage of the opportunity.”