Midwestern wind turbines could soon transform the air's energy into hydrogen and then into anhydrous ammonia and urea fertilizers. At least that's the intent of Minnesota and North Dakota researchers. Two pilot projects are underway there to demonstrate the commercial viability of producing nitrogen (N) fertilizers from wind-generated hydrogen.

“Our objective is to make the process significantly more economical than natural-gas-based fertilizers,” says Ted Aulich, senior research manager, Energy & Environmental Research Center (EERC) at the University of North Dakota. “We started working on this process about a year ago. We have demonstrated that it works. Now we intend to commercialize it.”

The process being developed at the EERC uses electricity and carbon dioxide, an ethanol co-product, hydrogen and nitrogen oxide (NOx), to produce urea fertilizer. NOx is a by-product of coal combustion, which can be trapped and removed from smoke stacks.

“In two to three years the project might have some possible sales of urea,” says Aulich. “We're currently a non-profit group, but it might be spun off later into a private company.”

Most N fertilizers are currently imported from overseas, where natural gas is the primary feedstock. “The price of nitrogen-based fertilizers has increased 100-200% over the last five years due to high natural gas prices,” says Aulich. “We're trying to create an alternative source that is economical, renewable, local and environmentally sustainable.”

Wind energy is already an economical and renewable energy resource, but converting it into hydrogen makes it more reliable and useful, says Tom Erickson, EERC associate director of research.

“Hydrogen production is one of the niche opportunities for wind, which is bountiful in North Dakota, and it helps to overcome the intermittences of wind energy,” he says.

Producing hydrogen from wind power will allow companies to store the wind's energy for later use, explains Erickson. “When the wind isn't blowing, hydrogen can be used in a fuel cell to supply electricity,” he says. “This system will give you a continuous stream of electricity.”

Hydrogen production should greatly improve wind energy's capabilities, agrees Mike Reese, renewable energy coordinator at the University of Minnesota West Central Research and Outreach Center (WCROC). The Morris, MN, researcher is currently working on a project to produce hydrogen from wind energy, with the ultimate goal to produce anhydrous ammonia.

“There are tremendous wind resources in our region, but wind is variable, and it's difficult to manage as a source of electricity,” says Reese. “This project is an attempt to store wind energy and add value to it.”

The project's first phase is to produce electricity and make hydrogen from wind energy, says Reese. The second phase is to produce anhydrous ammonia.

Phase I of the project could be of great value to utility companies that wish to incorporate wind energy into their electrical grids, points out Reese. For example, Xcel Energy has been paying wind farm owners whenever their turbines produce electricity, even if the utility isn't able to use that electricity. According to the Minnesota State Commerce Department, Xcel Energy paid more than $10 million from February 2004 to May 2005 for wind energy that it couldn't use due to insufficient transmission line capabilities.

The current WCROC wind-to-hydrogen-to-ammonia project is being funded with $2.5 million from a bonding bill, which the Minnesota Legislature and its governor recently signed, says Reese. The University is developing another $1.25 million to add to the project.

“Wind turbines will produce the electricity,” says Reese. “An electrolyzer will use that electricity to split water into hydrogen and oxygen. We'll store the hydrogen and mix it with nitrogen, from air, and send it through a catalyst to produce anhydrous ammonia.”

A year from now, Reese says he expects to have both phase I and phase II operational. “We want to validate the technology and answer the economic questions,” he says. “We hope to produce enough anhydrous ammonia for 600 acres, or about the amount needed for the research station's needs. If we produce any excess, we'll sell it through local co-ops.”

In addition to wind power, ethanol and corn stover may also play a role in increasing the energy efficiency of the process used to produce these N fertilizers. “Future research will look at a biomass gasification system to make hydrogen from corn stover,” says Reese. “We are developing a biomass gasifier to make a synthesis gas to use first for heating and cooling and eventually to scrub the hydrogen from it.”

Ethanol can already be used to produce hydrogen, either with or without help from wind energy sources, points out Aulich. “Ethanol is an excellent hydrogen feedstock, because it converts to hydrogen at a fairly low temperature,” he explains. “You don't need a lot of energy to heat it.”

Ethanol plants currently rely on distillation to separate ethanol from water, adds Aulich. By combining the process used to create hydrogen with the process to produce ethanol, the industry could potentially eliminate much of “the energy-intensive distillation required for ethanol production,” he says. “It would be a big a money-saving process.”

The EERC has already designed a reactor system specifically “to optimize the integrated ethanol to hydrogen process,” says Aulich. “We want to refine the economics of that process to add value to the industry.”

Hydrogen Economy On Its Way

Wind, ethanol and biodiesel energy sources are all compatible with a future hydrogen-based economy, says Tom Erickson, associate director of research at the University of North Dakota's Energy & Environmental Research Center (EERC).

“The transition from a petroleum-based to a hydrogen-based economy is likely to take a lot of time,” says Erickson. “The only way hydrogen is going to work in the future is if we have a number of different ways to produce it.”

Testing various alternative energy sources is the right approach for the future, agrees Lanny Schmidt, University of Minnesota chemical engineer, who helped develop a prototype reactor to efficiently produce hydrogen from corn-based ethanol. (For more information on this reactor, refer to page 15, August 2005 issue, “Corn-Fed Fuel Cells.”) “Pinpointing the future is difficult,” says Schmidt. “Nobody knows which technologies are going to work best to generate energy economically. So, it's best if we try a lot of different technologies and then let the marketplace decide. If one technology out of 10 works well, then we've been successful.”

Schmidt says that current wind-to-hydrogen projects that split water to create hydrogen have a lot of potential, because “when you electrolyze water, you make pure hydrogen,” he says. “Any impurities will disrupt the energy synthesis process.”

However, he adds that the limiting step towards a hydrogen-based economy is the demand for hydrogen, which is itself limited by the need for economically efficient fuel cells. “We're still waiting to develop markets,” says Schmidt. “We know how to make ethanol into hydrogen. That's certainly doable, but the economics of doing it are a little hard to pinpoint right now.”