Biomass Feasibility Project Final Report - Xcel Energy

cut energy consumption 10%. But his biggest energy-saving measure so far is a fluidized-bed
boiler that burns an ethanol byproduct, syrup, to reduce his purchases of natural gas. Corn Plus,
according to Kor, is the first company in the industry to adopt fluidized-bed technology. It has
received a patent on its application in ethanol production.
The fluidized bed boiler has raised the plant’s energy efficiency dramatically. Its ratio of outside
energy inputs to product energy output is down to one-to-six, and natural gas consumption has
dropped 55%. Kor now is working on a plan to make the plant completely independent of
outside energy, but details are not public.
Central Minnesota Ethanol Cooperative (CMEC) in Little Falls
Kerry Nixon, General Manager of Central Minnesota Ethanol Coop, is taking a different route to
energy independence. Working with engineer Cecil Massie, he has eliminated all natural gas
purchases by installing a gasifier fueled by wood wastes – sawdust, slabs, shavings, off-fall and
trimmings from loggers, sawmills and wood shops – available within a 20-mile radius of Little Falls.
It’s ironic that an ethanol plant, not a paper mill or a lumber mill, is the first facility in Minnesota to
gasify wood waste.
Gasification has acquired a reputation for being finicky about fuel, but Massie says it can handle
pretty much any kind of biomass as long as it contains less than 30% moisture. Slagging of silica
in the wood supply has been a challenge, though. Besides wood, the gasifier is set up to run
also on dried distillers grains (a byproduct of ethanol production), stover (corn stalks and leaves),
or straw. Since stover and straw contain silica, too, more tweaking will be needed to resolve the
slagging problem.
Stricter EPA permitting requirements and higher costs of natural gas are driving CMEC’s project.
The gasifier will enable the plant to meet lower VOC emissions levels without adding a thermal
oxidizer, which would use more natural gas; avoid $3.5 million per year in natural gas costs; and
co-generate about 30% of the mill’s electric load. The gasifier’s syngas also dries DDGs, and
conversely, DDGs could fuel the gasifier if getting wood fuel became a problem. Xcel Energy
will purchase 1 MW from the mill, but the plant will purchase 3 MW from the grid. The plant also
may sell steam to the city of Little Falls. Payback on the gasifier is estimated at three years.
Chippewa Valley Ethanol Company (CVEC)/Frontline BioEnergy, LLC, Benson
This is an important project not only in its own right, but also for the multiplier effect it might have
throughout the ethanol industry. A Minnesota cooperative ethanol producer, CVEC, and an
Iowa biomass gasification engineering firm, Frontline BioEnergy, have formed a joint venture to
design and install a prototype gasification system in CVEC’s Benson plant to process biomass
feedstocks like corn stover, distillers dried grains, corn, wheat straw and wood waste. The syngas
produced will replace $20 million worth of natural gas annually.
CVEC will pay the Iowa firm, Frontline, $3.4 million for research, $12.4 million for equipment, and
$1 million for working capital. In return, Frontline will give CVEC an equity position in its company
and licensing rights for a limited number of future installations in other plants. Both partners thus
will have an incentive to spread gasification technology to as many other plants as they can.
MUNICIPAL COMBINED HEAT AND POWER
European countries, especially Denmark, provide many examples of CHP plants that gasify local
biomass, like wood waste and crop wastes, to produce heat and power for small towns. Some
Identifying Effective Biomass Strategies: Page 83
Quantifying Minnesota’s Resources and Evaluating Future Opportunities