This is the second in a series of posts on findings from the Inventory of Missouri’s Estimated Greenhouse Gas Emissions in 1990, published by MODNR in 1996.

One of the most interesting findings of the GHG inventory was that burning fossil fuel to generate electricity was the largest single source of emissions in Missouri. It is a common finding. Electricity generation accounted for 51,539,000 short tons of carbon dioxide equivalent (STCDE), or 34.8% of all Missouri emissions. Of these, 51,239,000 STCDE (more than 99%) came from the burning of coal. Only 300,000 came from burning other fuels.

Why should emissions from electricity be so high? First, electricity is an amazingly versatile and flexible source of energy. We use tremendous amounts of it. It is the energy behind electric lighting, computers and TVs; electric motors power HVAC systems, industrial processes, refrigerating systems, even elevators and doors in buildings.

Second, in 1990 coal was used as the fuel to generate 82% of Missouri’s electricity. Other fossil fuels combined were used to generate less than 1%, while nuclear and renewable sources were used to generate almost 15%. Coal is one of the most GHG intensive fuels in common use. For the same amount of energy, coal emits 175 lb. of carbon dioxide for every 100 lb. emitted by natural gas. And for equal amounts of energy, coal emits 118 lb. of carbon dioxide for every 100 lb. emitted by fuel oil.

A third reason is that many power plants are old and inefficient. The average energy efficiency of power plants across the United States is 30-35%, even less in the oldest plants or in plants where the generating capacity of the plant is only partially used. The rest of the energy goes up the flue. Modern plants use a variety of technologies to increase efficiency to the 60% range.  In addition, some modern plants use natural gas, biomass, or alternative fuel sources, which can reduce GHG intensity even further.

The Labadie Plant, just outside St. Louis County, is one of the larger generating stations in the nation, releasing almost twice as much carbon dioxide into the atmosphere as the next largest power plant in Missouri. Labadie creates a lot of energy, however. I don’t have statistics from 1990, but in 2000 Labadie was middle-of-the-road in GHG intensity compared to other Missouri power plants, emitting 1,846 tons of carbon dioxide equivalent per megawatt hour generated. By 2009, other plants around the state had made such progress that Labadie was now in the top 25% in GHG intensity.

In 2000, four power plants tied for most GHG intense: the University of Missouri Combined Heat and Power Plant, the Anheuser Busch Power Plant, the Butler Power Plant, and the Kahoka Power Plant. By 2009, the Mizzou, Annheuser Busch, and Butler plants had all sharply reduced their GHG intensity, by more than 50% each.  The Kahoka plant, however, had increased its GHG intensity 73%. In 2009, the Carollton Power Plant was the most GHG intense in the state. I don’t know why GHG intensity at these two plants increased so drastically.

Source on Missouri electricity use: Missouri Electricity Profile, U.S. Energy Information Administration, http://www.eia.gov/electricity/state.

Source on fuel GHG intensity: Fuel Source Codes and Emission Coefficients, Voluntary Reporting of Greenhouse Gases Program, Energy Information Association. http://www.eia.gov/oiaf/1605/coefficients.html.

Source on average efficiency of power plants: What Is the Efficiency of Different Types of Power Plants, F.A.Q., U.S. Energy Information Administration, http://www.eia.gov/tools/faqs/faq.cfm?id=107&t=3.

Source on GHG emissions by Missouri power plants: CARMA, www.carma.org.