NRRI roasting wood to replace coal
COLERAINE — It seems like much of the world is plunging headlong toward renewable energy and away from fossil fuels and the carbon dioxide pollution they create.
Ontario has eliminated coal-burning power plants. China is phasing out internal combustion engines for new cars, as are General Motors and Ford. On Wednesday the International Energy Agency reported solar energy was the fastest-growing source of new electric power in 2016, the first year solar surpassed all other new energy sources, even coal.
But Don Fosnacht, associate director of the Natural Resources Research Institute at UMD, says the reality is that it will take years, even decades before the U.S. grudgingly moves to eliminate coal and oil from its energy mix.
"Until then, we need a bridge, a transition that has fewer emissions than coal but can still be used in existing technology," Fosnacht said.
Fosnacht is leading the NRRI's Renewable Energy Initiative team that's developing a coal substitute made from roasted wood. On Wednesday they showed off their results at the institute's Coleraine Research Laboratory, a sprawling 27-acre facility with mining-size buildings and hulking equipment to match.
It's been a 10-year effort, but the NRRI has gone from the laboratory scale, to pilot-size project to demonstrate size — big enough to produce the quantities needed to test at power plants and other customers who are looking to move away from coal.
It's called torrefaction, where woody biomass — tree tops, limbs and other parts that aren't used to make paper or lumber — is slow-roasted in a kiln at 550 degrees, ground to a powder and then pressed into briquettes that look a lot like charcoal for backyard grills.
Better than coal?
Those briquettes can be used instead of coal, in the existing coal-burning power plants. The process concentrates the energy of the wood, producing 11,000 BTUs per pound, considerably more than 4,500 BTUs for raw (wet) woody biomass and even more than 8,500 BTUs for coal or dried wood pellets.
Portland General Electric recently tested 5,000 tons of the coal substitute, simialr to what NRRI produces, at their Boardman, Ore., coal-fired power plant. They burned 3,500 tons of NRRI torrefied wood without any coal "and it worked great for them," Fosnacht said. They also burned 1,500 tons mixed with coal "and that worked, too."
"Oregon is trying to eliminate coal (burning in power plants) by 2020 and what Portland General Electric found is that they can use (the roasted wood) material in the same coal burners without having to spend hundreds of millions of dollars to make a change," Fosnacht added.
The roasted wood also has lower carbon emissions than coal and produces virtually no mercury pollution.
But torrefied biomass also can beat so-called dried "white" wood pellets, a growing U.S. export feeding Europe with biomass energy as nations eliminate coal from their power mix. Those wood pellets have about the same energy value as coal but require major changes in technology.
"The U.S. is shipping 1.1 million tons of white wood pellets to Europe every month. We have more BTUs, fewer emissions and we can ship it and store it better than wood pellets," Fosnacht said.
Ontario Hydro recently spent $165 million converting its Atikokan coal-burning power plant to accept wood pellets, Fosnacht noted.
"They could probably have burned our material without spending much at all and got better results," he said. "We may be able to let (utilities) get more use out of these old plants, which saves money for their customers, and still meet their (carbon cutting) goals."
The NRRI's proprietary torrefaction process, if adopted by large energy producers, could stimulate business for Northland wood products industry, helping maintain forest management and bringing in more money to the low-margin business of cutting and trucking trees to market.
From wood to synthetic gas
NRRI officials also say the torrefied wood and other biomass — such as corn stalks, weeds and invasive species — can be further refined into synthetic gases. NRRI is part of a growing effort to see if gases made from biomass could someday be refined into jet fuel, diesel fuel and special-order gasoline varieties.
NRRI is partnering with private Syngas Technologies, LLC to build a $2.5 million device at the Coleraine lab that will use steam and pressure instead of dry heat to torrefy biomass intended to be refined further into gases.
"The goal is to seek out the highest and best value for our natural resources. It's good we have industries that get $2 per board foot for wood products ... but it will be great if we can also diversify to wood products that create something that's worth $1,000 per kilogram for Minnesota," said Rolf Weberg, NRRI executive director.
Wood waste form the Iron Range, Weberg noted, could someday be made into jet fuel for Delta Airlines.
Right now, with $3-per-million BTU natural gas available in the U.S., $48-per-barrel oil and Powder River western coal at just $11 per ton, synthetic fuels from biomass may not be financially competitive with fossil fuels.
"We're sensitive to the costs that are out there right now," said Todd Simons, Minnesota Power's manager of renewable operations, said. "But we fully support the research and direction this is going. We need places like this that the NRRI has to kick-start some of these technologies."
Simmons noted that the torrefied biomass also can be used to create activated carbon, again replacing coal, that can be used in wastewater treatment and other cleanup applications.
Weberg said it's up to the NRRI to do the homework to be ready when economics change and the value of Minnesota's biomass jumps.
"When people are ready to put the true cost of using (fossil fuels) into the prices, then we'll be ready to jump in and replace them," Weberg said. "That's NRRI's mission, to be setting the stage, looking ahead."