5-2-08

Co-firing Biomass is Front if not Center in Utility Plans - Hot Topic Hour Yesterday

On May 1 utilities, suppliers and government experts answered questions and described all the options for co-firing biomass. There is lots of interest because utilities know this will be one of the least expensive ways to meet future CO₂ regulations. But it is not center stage. Some research is going forward but it is modest. On the other hand there is lots being done in Europe, so the U.S. need to learn from them.

Southern Company is moving forward with its testing program. Tom Johnson described their experience with both switchgrass and small wood chips. Switchgrass comes in bales and goes through a tub grinder before it is pneumatically conveyed to dedicated burners which are above the coal burners. Co-firing ranges from 5 to 10 percent at the Gadsen. However it is not continuous. Small wood chips (less than ½ inch) can be fed through the coal pulverizers. Larger chips would cause problems. There is not likely to be a problem with the quality of the ash but a new ASTM specification would be needed. The one problem other than supply would be concern about effect on the SCR catalyst. European experience shows only a slightly reduced catalyst life. But Southern would like to directly evaluate performance.

Larry Swanson of GE Energy told the participants that an additional 60 percent NO_x reduction can be obtained by injecting the biomass as a reburn fuel rather than primary fuel. It takes as little as 15 percent biomass to obtain greater than 50 percent NO_x reduction. A fuel flexible process allows injection of either biomass or coal as the reburn fuel. GE is presently looking for a beta site to move to full scale demonstration with this technology.

Tim Hansen of Southern Research Institute described use of biomass at two spreader stoker boilers. With 15 percent biomass there was a net 10 percent CO₂ reduction. SO₂ and NO_x were also reduced. In one unit when biomass was increased above 90 percent, condensable particulate emissions were reduced by more than 80 percent. There were also reductions in HCl, HF, and primary metals.

Mark Freeman of DOE NETL provided lots of background information on the projects. He indicated that DOE is putting lots of emphasis on biofuels. There are implications for co-firing. He showed a 25 million gallons per year (gpy) cellulosic ethanol plant providing 10 percent of the fuel for a 400 MW coal-fired power plant.

Mark did not take this further but we have. The goal is 75 billion gpy of cellulosic ethanol. There would be enough waste to generate 120,000 MW of electricity. Put it another way you could co-fire 33 percent biomass at every coal-fired power plant in the country. Last week we reported on the Spiritwood Energy Complex, which will be 66 percent efficient because the coal-fired low pressure steam will be used to make ethanol. This is a corn-based plant. If this were a cellulosic plant you could have chlorinated cellulosic waste to co-fire in the coal-fired boiler and steam and hydrochloric acid to supply to the ethanol plant. We have said before that the coal generator and ethanol plant union is a marriage made in heaven. It is the first time there is a heat user large enough to make a significant difference in the coal-fired power plant net efficiency. Now ethanol may be the one source of biomass large enough to make co-firing practical at every plant.

Mark was very helpful in guiding participants to a number of valuable documents available on the web. Here are the links.

The Handbook of Biomass Combustion and Co-firing (updated December, 2007)

http://www.earthscan.co.uk/default.aspx?tabid=1429

1) U.S.

EIA Biomass Co-firing Database by Plant Name & State in the U.S.

http://www.eia.doe.gov/cneaf/solar.renewables/page/trends/table9.html

EIA Renewable Energy Annual Outlook for the U.S.

http://www.eia.doe.gov/cneaf/solar.renewables/page/rea_data/rea_sum.html

Bioenergy Feedstock Information Network (BFIN)

http://bioenergy.ornl.gov/

DOE Bioenergy Program

http://www.doe.gov/energysources/bioenergy.htm

2) International

IEA International Biomass Co-firing Database by Plant Name, Country, etc.

http://www.ieabcc.nl/database/cofiring.php

http://www.ieabcc.nl/database/cofiring.html

IEA Bioenergy Task 32 Activities ... scroll down this link and you can find interesting information, including a detailed study on the public perception of biomass co-firing for numerous countries published in 2004.

http://www.ieabcc.nl/

IEA Summary Papers

http://www.ieabcc.nl/publications/paper_cofiring.pdf

http://www.ieabcc.nl/publications/Task 32 end-of-task report.pdf

Integrated European Network for Biomass Co-firing (NETBIOCOF)

http://www.netbiocof.net

Recent European Conferences

1st Conference of the European Biomass Co-firing Network (NETBIOCOF) in Budapest during July 2-4, 2007

http://www.netbiocof.net/conference.html

International BIOENERGY 2007 Conference in Jyväskylä, Finland during September 3-6, 2007

http://seminaarit.ohoi.fi/default.asp?seminarID=6

Biographies and pictures of speakers are shown at Bios and Photos of Speakers at Co-firing Biomass