Combined Cycle Natural Gas Fired Power Plant

Q.        What is it?

A.        A combined Cycle Natural Gas Fired Power Plant is an electricity production facility that burns natural gas as its fuel and uses more than one thermodynamic cycle to produce power.  

The first cycle works just like a jet engine.  Air enters a gas turbine where it is compressed, mixed with natural gas and ignited, which causes it to expand.  The pressure created from the expansion spins the turbine blades, which are attached to a shaft and a generator, creating electricity.

The second cycle captures the heat energy that is expelled from the turbine (and would otherwise be lost in a simple cycle plant) and uses it to heat water.  The water becomes steam, which expands and is forced through another turbine that creates electricity in the same manner. 

Q.        What types of emissions do combined cycle natural gas fired power plants put off?

A.        The main emissions produced by combined cycle natural gas fired power plants are nitrogen oxide (NOx), Carbon Monoxide (CO) and carbon dioxide (CO2).  While NOx and CO emissions are generally very low and particulate emissions (dust, smoke, etc.) are non-existent, the distribution of CO2 is a realistic concern.  That being said, the typical combined cycle natural gas power plant emits about 50% of the amount of CO2 per kw/h as a typical coal or petroleum fired power plant.  This makes natural gas fired combined cycle power plants desirable replacements for traditional fossil fuel burning plants.  The federal and state governments regulate power plants to a very strict level and require the application of Best Available Control Technology (BACT) standards to minimize impact to the environment.  See chart below.

A major study performed by the Environmental Protection Agency (EPA) and the Gas Research Institute (GRI) in 1997 sought to discover whether the reduction in carbon dioxide emissions from increased natural gas use would be offset by a possible increased level of methane emissions. The study concluded that the reduction in emissions from increased natural gas use strongly outweighs the detrimental effects of increased methane emissions. Thus the increased use of natural gas in the place of other, dirtier fossil fuels can serve to lessen the emission of greenhouse gasses in the United States.

Q.        What would it look like?

A.        Generally speaking, this type of plant would look like a large building (details to be determined through the master plan process) about 90-feet tall with one cooling tower about 150-feet tall.  All equipment would be contained within the primary building.  Requiring an enclosed facility would have the effect of minimizing both the visual impact and any noise emissions associated with the plant.

Q.        What are the benefits?

A.        The benefits of having such a plant are many.  First off, the assessed valuation of such a facility would approach $500M.  This would add significant new general fund taxes to the community and would go a long way toward diversifying the tax base beyond single family homes and a small amount of commercial property.  Plants such as this generally employ 50 or so full-time people at living-wage and above salaries.  Additionally, during construction, nearly 300-workers from a broad range of trades would be employed. 

            In relation to the Keizer Station site, any plant constructed would utilize nearly 3M gallons of effluent from the Willow Lake sewer treatment plant daily.  The effluent would be piped to the facility and then treated on-site to a level of purity equal to or better than drinking water.  The treated water would then be used as coolant and 90% or more would be evaporated as pure steam.  The remaining purified water would be piped back to the sewer plant for retreatment.  This process would significantly reduce the amount of effluent discharged by the sewer plant into the Willamette River and would create a significant environmental benefit.