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Examining alfalfa’s potential as a fuel

Examining alfalfa’s potential as a fuel

By KEVIN TREVELLYAN
ktrevellyan@postregister.com
Bales of alfalfa, 1,300 pounds each, sit behind a facility at Idaho National Laboratory’s Idaho Falls campus. The hay would have been eaten by cattle long ago, but it is contaminated with inorganic bromide.
The bromide came from methyl bromide, a highly toxic pesticide that was sprayed on eastern Idaho farmlands after a rare potato pest was found in 2006.
Progress has been made with the pale cyst nematode, but bromide remains in some of the soil, and some of the crops grown in it.
Employees at INL’s Biomass Feedstock National User Facility are studying how farmers can squeeze some value from contaminated alfalfa as a combustible fuel. The research is unique, and results have shown promise, facility Advisory Engineer Michael Clark said.
“Alfalfa was not something we looked at because it has a more beneficial use as feed, but you have farmers with a crop sitting in their stack yard — they have that same plant growing in the field — and they’re going ‘What should I do?’” he said. “I think there’s a market for it.”
The extent of field contamination was not realized until methyl bromide treatments stopped in 2014 after a farmer began to notice side effects in cattle that were fed from crops grown in the treated soil.
Cattle fed hay grown on the fields experienced lesions, stillbirths and other health issues, including death. Farmers filed a lawsuit against state and federal officials arguing the nematode treatment was “ad hoc” and “overreaching.”
About 2,000 acres of farmland in Bonneville and Bingham counties owned by more than a dozen growers are still within the Idaho Department of Agriculture’s pale cyst nematode program, Administrator at the Division of Plant Industries Lloyd Knight said, though not all farmers are experiencing bromide issues.
Alfalfa is grown as a rotation crop, and because there’s restrictions on what farmers can grow under the nematode program. It represents a small percentage of crops grown in contaminated soil, Knight said.
Some crops, such as wheat and potatoes, contain lower bromide concentrations than alfalfa. State and university researchers are still trying to find out why.
“That’s what we’re struggling with: how low levels of bromide in the soil result in high levels of bromide in certain crops,” Knight said. “We’re not quite sure we’ve figured out the biological mechanism.”
In the meantime, questions remain over what to do with crops that have been and continue to be grown on contaminated fields.
Landfilling what has become 5,000 tons of alfalfa was considered, but officials wanted to find a more sustainable use. The Biomass Feedstock National User Facility at INL was the perfect resource to turn to, Knight said, as it contains nationally unparalleled resources.
The warehouse-like biomass facility contains a staff of researchers and large conveyors, grinders, bag filters and pellet mills, among other things.
The U.S. Department of Energy created the facility as a “sandbox” for the agriculture and bioenergy industries to overcome challenges processing biomass that often doesn’t have a market. Employees have conducted research on corn stalks, leaves and cobs, for example, that have no immediate use to Midwest farmers growing corn for human or animal consumption.
Facility employees research how to make new products economically feasible — is something profitable after the cost incurred turning it into a product?
“You’re taking biomass residues and making them into a valuable commodity you can buy, sell and trade,” Clark said. “In the real world these companies wouldn’t necessarily have the capital, time and resources to do that research without us.”
State officials approached Clark about a year ago to research potential uses for alfalfa apart from feeding it to cattle.
“And I thought ‘What if we burn it as a fuel?’ Companies already have power plants. What if you can feed them something that’s not coal, but acts like coal, looks like coal and is able to process like coal?” Clark said.

Local potato processing companies use large amounts of heat for daily operations. Representatives told Clark they’d pay $15 to $18 a ton for alfalfa fuel they can burn in their coal-fired plants, but they needed to know it was safe.
“If it’s killing cows, what’s it doing to people?” Clark said. “Before we start burning it, we need to know if the (Environmental Protection Agency) is going to come shut us down because we’re emitting materials.”
Clark’s team donned respirators, suits and gloves at the biomass facility, then monitored air to see if bromide was released at any point that alfalfa is processed into fuel. The process takes bales weighing 12 to 15 pounds per cubic foot and transforms them into pellets or cubes weighing 40 to 50 pounds per cubic foot.
Researchers found bromide was only released during an emergency procedure in the pellet-forming process, and not at all otherwise.
Burning the fuel yielded no bromide to the air. It stayed in the ash, Clark said, which can be used to produce cement.
“You’re diluting it and stabilizing it. Could it be a problem in the future? Possibly, but you’ve got a disposition source, and you know where it is,” he said.
Amid growing sentiment against coal-powered electricity, alfalfa could be an attractive fuel source, Clark said. Carbon dioxide emissions are likely comparable to coal burning, but carbon dioxide isn’t added to the atmosphere.
“With biomass you’re pulling CO2 out of the air with photosynthesis while the crop grows. It’s available carbon you’re returning to the air, but you’re not digging it out of the ground and liberating it,” Clark said. “You can argue there’s emissions transporting it, but you’re still greatly reducing carbon you’ve put into the system.”
Researchers have shown alfalfa can burn as a fuel, but there’s still work to be done.
Pure alfalfa fuel tends to “foul” burning chambers, leaving a material not unlike creosote caked in a home chimney. Combustion could be increased by mixing another biomass with the alfalfa, Clark said.
“It could be as simple as changing your recipe. Maybe we make a pellet or briquette with 60 percent alfalfa and 40 percent wood slash,” he said.
State officials are negotiating with INL researchers to determine additional research steps regarding emissions and ways to make the fuel more viable.
Knight said if a market is established for the fuel, the state would like to remove itself from the alfalfa equation and let growers sell their crops.
Clark doesn’t think that’s out of the question.
“We know we can use the alfalfa; we just need to figure out some of those obstacles,” he said. “And to farmers, you can say ‘Go ahead and grow your alfalfa. The fuel may not be as cost-beneficial as growing it for feed, but there’s a path forward and we’re not just putting it in landfills.”