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Scientists see biochar as promising fuel source

Source:  Copyright 2010, News Tribune
Date:  February 28, 2010
Byline:  Kevin McCullen
Original URL: Status DEAD


Scientists in Eastern Washington are at the forefront of research into an ancient practice that shows promise as a clean fuel source, a way to improve soil condition and to capture carbon that otherwise would be released into the atmosphere.

Researchers from Pacific Northwest National Laboratory, the federal Department of Agriculture's research station in Prosser and Washington State University have been integral figures in studies of biochar and its potential uses.

Biochar, a charcoal-like material, is produced when biomass -- including wood, plant and animal waste -- is burned in the absence of or under low oxygen conditions so the material doesn't combust.

This process, called pyrolysis, thermally decomposes the waste into biochar, bio-oil and syngas. Biochar and bio-oil show commercial promise and syngas offers a power source that can run a pyrolyzer.

The USDA's Agricultural Research Service has estimated that if the United States were to pyrolyze 1.3 billion tons of various forms of biomass annually, it could replace 1.9 billion barrels of imported oil with bio-oil. That would represent about 25 percent of the annual oil consumption in this country. In addition, USDA estimates the country could sequester 153 million tons of carbon annually by adding biochar to soils.

Although widespread research on biochar began less than a decade ago, debate already is brewing on whether its prevailing commercial use will be for fuel or for soil and carbon sequestration.

In January, UOP, a subsidiary of the Honeywell Corp., announced it had been awarded a $25 million grant from the federal Department of Energy to build a demonstration plant in Hawaii to take waste feedstocks of wood, agricultural products and algae residue to produce bio-oil. The oil then will be refined into aviation and diesel fuel with technology developed in part by PNNL, a junior partner in the project.

Biofuels, including bio-oil from char, "can't replace all petroleum," said Doug Elliott, staff scientist with PNNL's Chemical and Biological Process Development unit. He has been researching biofuels for three decades.

"But U.S. production of biofuels could replace one-third of our total petroleum products annually and on a continuing basis," he said.

Could create jobs

Or the use of smaller portable pyrolyzer units one day could be deployed in forests to clean up wood waste piles, produce lower-grade fuel, generate power and create jobs in rural communities. The Forest Service is funding research of a small demonstration project in a small Northeastern Oregon community.

"There's all kinds of things that are potentially usable as a fuel source. You can make this work on a whole lot of things that don't have a value and actively have a cost," said Eric Twombly of BioChar Products, who is conducting the forest fuels project in Halfway, Ore.

Twombly fired up his mobile plant in December at an old lumber mill site about eight miles from the Idaho border. He hopes to produce at least 500 tons of biochar and at least 300 gallons of bio-oil using chipped wood waste.

A farmer already is buying some of the oil to use in his orchard heaters, and Twombly uses the syngas to power the plant. It now employs three people, but Twombly envisions one day creating at least a dozen full-time, family-wage jobs.

And ongoing research by soil scientist Hal Collins and his team at the USDA's vegetable and forage crop research unit in Prosser is looking at how dairy waste could be transformed on-site into a product that could be added to the soil, used as an energy source and to eliminate the environmental concerns of waste ponds.

Jim Amonette, a soil chemist at PNNL who has extensively studied biochar, and others say it isn't a panacea that will resolve the nation's energy and environmental challenges. But he says its potential use in storing carbon and as a soil amendment is promising.

"You are basically taking a biomass that would be back in the atmosphere in five to 10 years and converting it into biochar that will be in the soil for hundreds to thousands of years," said Amonette, who contributed a chapter to Biochar for Environmental Management, considered one of the definitive reference works on the topic.

"It is one of the few ways you can pull carbon out of the air and generate energy at the same time," he said.

Different products

The process isn't new. Researchers have found areas in the Amazon basin where people centuries ago deposited charcoal, leaving behind areas with rich soils and lush plant growth. Scientists aren't certain how they created the charcoal, said David Granatstein, a sustainable agriculture specialist at Washington State University and a co-principal investigator of a study published last year.

Scientists subsequently have found that different methods of pyrolysis -- fast and slow, which are distinguished primarily by the rate of temperature increase in the pyrolyzing unit -- produced different amounts of finished product.

Fast pyrolysis takes place in seconds, with temperatures that can reach up to 1,000 degrees. WSU researchers and Collins found in their study, released in 2009, that higher heating produced more bio-oil and less biochar from the same amount of biomass, while slow pyrolysis with slow heating rates yielded more char and less oil.

Amonette said research of the two methods in general has shown that a ton of biomass subjected to slow pyrolysis can produce up to 750 pounds of biochar, while the fast process yields 300 pounds of char.

Pressure to produce bio-oil could grow as oil prices continue climbing. UOP has said it expects to start fuel production in Hawaii no later than 2014. The company estimates it could produce gasoline and diesel for about $2.50 a gallon, Elliott said.

Others, however, tout the potential value of biochar for use in soils and in controlling greenhouse gases. Production of biochar locks up carbon from the biomass that would otherwise rot or be burned, and therefore decreases the amount of carbon dioxide returned to the atmosphere, according to researchers.

"By finding ways to keep this carbon out of the atmosphere for longer periods, we're making better use of the service provided by plants when they remove carbon dioxide from the atmosphere during photosynthesis," Amonette said.

Soil scientists also have found biochar is good for storing carbon because it takes a long time to decompose, Collins said. It also has shown promise in retaining phosphorous, nitrogen and potassium -- helping prevent them from leaching into lakes and streams -- and retains moisture because it is porous.

But research by soil scientists thus far suggests biochar isn't a magic elixir for all types of soil. It may work best in tropical and highly weathered soils -- such as in the southern U.S. -- where minerals have leached out of soil.

"It's not a nutrient. It imparts some characteristics that improve soil conditions," Collins said.

His team in Prosser now is looking at transforming dairy wastes into a fuel source and reducing environmental issues with the waste. The researchers are taking manure run through a digester at an Outlook dairy, running it through a pelletizer to change it to pellet form, and then subjecting it to slow pyrolysis to produce bio-gas or bio-oil.

Biochar produced in the process is being applied to dairy waste water to remove excess nitrogen and phosphorus, which could be sold as a fertilizer.

"We think it shows a lot of promise," Collins said.

Research will yield more clues into potential applications of biochar and bio-oil. Economics also will play a key role in how the technology is developed, said Jim Bartis, a senior policy researcher at the Rand Corp. who specializes in energy.

"We know we can implement (the technology) now on a small scale," Amonette said. "We can't wait 50 years to get all the bugs out."

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