Hot Topic Hour Recordings

May 31, 2007

Biomass Co-firing Makes Sense in Lots of Ways - This is the Conclusion of our Hot Topic Experts

Lots of experience and expertise were displayed on May 31 in a very good discussion of biomass and its use to generate electricity. Dave Tillman has the hands on experience at Foster Wheeler and Detroit Edison to caution that while biomass co-firing has lots of advantages it also has lots of potential problems. The potential problems are primarily in material supply and handling. So the advice is to proceed but to take advantage of lessons learned.

Boris Eiteneer of GE made a good case for biomass reburn. In terms of NO_x reduction it is better than most other fuels. It is more effective if introduced as particles rather than as a gas. This applies to wood and agricultural waste. When you consider sewage sludge and other less desirable waste fuels, gasification makes more sense. In either case reburn can provide both increases in output and decreases in emissions. He also pointed out that biomass accounts for more electricity production than any of the other better publicized renewable options.

Ken Ragland of Energy Performance Systems Inc. explained that you can grow hybrid poplar trees and with a novel system burn whole logs. The area required for planting would be about two percent of the land in a 50 square mile area around a 100 MW plant. So this is an interesting alternative to co-firing for Wisconsin, Michigan, and other areas with the proper climate and available land.

Pat Travis of Energy Products (EPI) pointed out that the advantage of fluid bed gasification of biomass is the fuel flexibility. The company has decades of experience in the industrial arena and has had successful demonstrations in the utility industry including a program at Nebraska Public Power. EPI is supplying fluid bed combustors for ethanol plants. PRB coal is the typical fuel. APC equipment is usually a dry injection or spray drier system followed by a baghouse. SNCR has been used in most ethanol plants burning coal for NO_x control.

Bill Guyker, formerly of Allegheny Energy, pointed out that the whole co-firing question is dominated by regulations This observation can be expanded to say that environmentalists and lawyers are going to have a big impact on what is done.

The UK situation is such that every coal-fired plant co-fires biomass. Furthermore the quantities are increasing. Fiddlers Ferry is utilizing 20 percent biomass. The 4,000 MW Drax plant will grow biomass to account for 10 percent of energy input.

Doosan Babcock had wanted to participate in this discussion but was unable to do so. We have included an older power point presentation in our Decision Tree and will replace it with something more current. But the older power point does lay out the very active biomass co-firing program.

Here are the McIlvaine thoughts based on the meeting and lots of research in this area.

A new approach is needed to permit either a new power plant or a new ethanol plant using a coal-fired generator. The same is true for expanding an old coal-fired power plant.
Biomass is the “magic” word which starts the dialog with the environmentalists. Also incorporate “ethanol” and you have the environmentalists with you instead of against you.
Reburn can result in increased steam production.
The excess steam can supply a co-located ethanol plant.
You can also make hydrochloric acid and capture and concentrate mercury.

THERE IS A HUGE POTENTIAL SYNERGY WHICH NEEDS FULL EXPLORATION. A cellulosic based ethanol plant is co-located at a coal-fired power plant. The lignins from the ethanol plant are used in a gasifier to deliver reburn fuel to the coal fired boiler. (EPI has positive experience here.) The waste steam from the coal-fired power plant supplies the energy needs for the ethanol plant.

Another big potential is the production of hydrochloric acid and the capture and concentration of mercury (there is a big interest in avoiding gypsum contamination). A feature article by McIlvaine in Chemical Engineering this month has the details and schematics on this. The article is included in the NO_x Decision Tree below.

McIlvaine is preparing a feature article on this subject for the July Power Engineering magazine. If you have any additional comments for use in the article or our newsletters and Alert please contact us.

The entire 2.5 hour webinar can be viewed through the following link:

Co-firing and Gasifying Biomass 154 minutes

The individual power points are incorporated in the NO_x Decision Tree through the following links (the EPI material will be added later):

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Cofiring