New technology aids coal-biomass gasification

May 9, 2011, Durham, NC – Southern Research
Institute’s Clean Energy Technology Development Center in Durham, North
Carolina, has achieved an important milestone in the effort to find low-cost
technologies that reduce greenhouse gas emissions from coal-fired power plants.
The technology development, a collaboration between Southern Research and TK
Energi A/S of Denmark, successfully combined both coal and biomass feedstocks
for use in coal-fired power stations of the future called Integrated
Gasification Combined Cycle (IGCC) systems. The use of biomass as a
supplement to coal could allow power stations to take credit for the carbon
dioxide from biomass. The program was sponsored by the U.S. Department of
Energy, with additional financial support from Southern Research and TK Energi.

In contrast to bulky and expensive
lockhoppers, the prototype feeder creates a highly compressed plug of coal and
biomass so dense that the high pressure inside commercial-scale gasifiers is
held back as the material is pushed into the gasifier. A primary challenge
related to biomass use in IGCC power plants has been the inability to reliably
feed a variety of biomass feedstocks to the gasifier as biomass-coal
mixtures. Southern Research and TK Energi have shown this challenge can be
overcome.

"When we reached 450
pounds/square-inch of pressure, and the feeder was still holding back pressure
and increasing in feed rate, we knew we had a winner," says Dr. Santosh
Gangwal, project leader for Southern Research.

The prototype piston-driven plug feed
system was demonstrated using a blend of two coal types (bituminous and
lignite) and three biomass feedstocks (woody biomass, prairie grass, and corn
stover) fed into a pressurized simulated gasifier environment up to 450
pounds/square-inch.