The biggest misconception has to do with the use of coal to convert corn or switchgrass into ethanol. The substitution of ethanol for gasoline has a very big net CO2 reduction effect. The use of coal instead of natural gas to provide the heat and steam does not significantly reduce the benefit.
What has been missing from analyses of the greenhouse gas aspect of ethanol is failure to consider the CO2 and methane emissions generated in the oil and gas production, refining and transport of petroleum fuels. It takes more energy to produce a gallon of gasoline than it does a gallon of ethanol. This is without taking into account any of the energy required for security reasons.
When you also consider that the corn or crop absorbs as much CO2 as the ethanol releases, you have more than 100 percent reduction in greenhouse gases when you substitute ethanol for gasoline. So if all transportation fuels which generate 20 percent of greenhouse gases in the U.S. were replaced with ethanol, you would have more than a 20 percent reduction in greenhouse gases.
The difference between use of natural gas and coal for ethanol heat and steam makes almost no difference in greenhouse emissions. The cost of making ethanol with coal is considerably less than with gas. Cost is a factor in production. It would take only a 1 - 2 percent increase in ethanol production to achieve a net gain in CO2 reduction using coal for all ethanol plants instead of gas.
There is a very big potential to use the waste heat from a coal-fired boiler to provide the heat and steam for the ethanol plant. Two such plants are under construction. In this situation there is no CO2 emissions from the ethanol production.
It is not always possible to co-locate the electricity generator and the ethanol plant, but in one case an existing coal plant has been selected as the site for the ethanol plant. In the other a new generating plant is planned along with the ethanol plant and other heat and steam consuming facilities. There is lots of opportunity to achieve this synergy.
Synergy can also be achieved by co-locating a variety of energy using industries at coal plant sites. In Europe combined heat and power, including those facilities providing residential heating and cooling, produce 40 percent less greenhouse gases per unit of usable energy produced.
The biggest reduction in CO2 can be accomplished by replacing old coal-fired plants with new ones. The most efficient coal-fired electrical generating plants release 30 percent less CO2 than the oldest least efficient plants.
Environmentalists have already recognized the CO2 reduction benefits of integrated gasification combined cycle (IGCC) plants. But pressurized fluid bed combustors (PFBC) and super critical conventional pulverized coal boilers have nearly the same CO2 reduction benefits. Regarding other pollutants, all these plants can be cleaned to any level required.
The attractiveness of super critical coal-fired plants is that they are long proven. Experienced suppliers can deliver them in quantity now. A new super critical coal-fired plant which replaces an old one would typically reduce CO2 by 30 percent, NOx by 95 percent and SO2 by 98 percent.
This subject will be discussed in a “hot topic hour” arranged by McIlvaine and is also analyzed in detail in World Market for Your Products: http://www.mcilvainecompany.com/worldindbrochure/worldindcharts/worldindbrochure.htm.