Overcoming the Coal Conundrum

Researchers at North Carolina State University think we should head back to the future – that wood might be able to replace coal, as the world’s primary energy source, just as coal once replaced wood. The NC State researchers are part of a team that is using a process called torrefaction to turn woodchips into a new fuel that is greener, cleaner and more efficient than burning coal. And, as Triple Pundit readers know, coal is the dirtiest source of energy on the planet. NASA climate scientist James Hansen says that reducing the use of coal must be our number one priority if we’re to save the planet.
During torrefaction, woodchips go through a machine – an industrial-sized oven – that toasts the biomass to remove any moisture. The chips are physically and chemically altered in this low-oxygen environment to make them drier and easier to crush, so they retain 80% of wood’s energy content, but just one-third of the weight, making them an ideal feedstock for power utilities that traditionally burn coal.

Torrefaction is not a new process, but the world hasn’t seen anything like NC State’s Autothermic Transportable Torrefaction Machine (ATTM), a portable and largely self-heated torrefier that can be used in the field, thereby reducing the cost of transporting woody biomass to power utilities. Even better, ATTM is also largely self-powered, producing a large energy return while also removing carbon from the atmosphere.
“This process could help us build a bridge to more energy independence,” says Chris Hopkins, a doctoral student in forestry at NC State and developer of the torrefier machine. Woodchips are a low-carbon energy source, and they could help states like North Carolina – which spends $4 billion annually importing coal – keep more of their hard-earned dollars at home, and put people to work tending their abundant forests. Hopkins estimates that if woodchips were collected and sold to power utilities in his state, the tax base would expand by $400 million. Many states and provinces with similar natural resources could benefit in the same way.
The first commercial machine should be available late this year. NC State’s Office of Technology Transfer (OTT) announced an exclusive license agreement with AgriTech Producers in South Carolina to commercialize this technology under the brand name Carolina Coal.

Richard is a writer and editor based in Halifax, Nova Scotia who specializes in clean technology and climate change. He's the founder of One Blue Marble, a climate change activism blog and web site.

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