Technology Research Area:

Biomass Direct Generation

What is biomass direct generation, and what does it have to do with TVA's mission?

Biomass is any organic material used as a renewable energy source. Renewable energy has the potential to greatly reduce overall greenhouse gas emissions and could help reduce global warming. It could also reduce other pollutants released into the air during conventional power generation. TVA is committed to using more renewable energy sources for generating power.

Direct power generation with biomass means burning biomass by itself to produce electrical power. Biomass may also be mixed with coal to produce power in a process called co-firing.

What is TVA doing about it?

TVA is investigating the use of biomass for the direct generation of electricity by converting a coal-fired plant to 100 percent biomass generation.

What are the possibilities for biomass direct generation?

Direct firing of biomass for power generation is a technology that is ready for commercial use. Direct biomass power generation usually uses stoker and fluidized-bed boilers.

Alternatives to direct generation include:

• Modifying pulverized coal boiler systems to burn biomass
• Replacing existing systems at the end of their useful life with new systems built for biomass
• Building entirely new plants dedicated to burning biomass
• Adding gasification to existing boiler systems, allowing biomass to be transformed into syngas for more efficient production of power.

Many of these technologies are already in commercial use. Some, such as gasification, are not yet well established on the larger scale required by electric utilities.

What are the potential drawbacks of biomass generation?

Biomass could become expensive if supply does not keep up with increased demand.

Biomass has a lower heating value than coal, and overall generation efficiency would drop if biomass generation increased.

Alkali in biomass could degrade equipment used to control emission of pollutants at fossil plants.

What would be the rewards of biomass generation?

When biomass fuel is grown sustainably, there is no net increase in carbon emissions. This is a great advantage in the battle against global warming.

Biomass is less expensive than other renewable energy sources. Using more of it could benefit local economies.

Converting biomass to fuel reduces the amount that goes to landfills, where it decomposes to produce carbon dioxide and methane. Biomass generation could reduce these sources of greenhouse gases.