Pillar to Post: Peter Welander's Blog
News and comment from Control Engineering process industries editor, Peter Welander
Coal troubles: As if carbon isn't bad enough
In what is a real-life example of “pick your poison,” coal-burning power plants are dealing with a choice of spewing out sulfur dioxide that results in acid rain, or mercury that contaminates fish and causes birth defects. We won’t even get onto the topic of carbon emissions.
This is manifest in rising levels of mercury in a number of mid-western states, including Illinois, that come from coal-fired power plant stacks. The tradeoff in this case relates to the fact that many of the western coal fields in the Powder River valley have an unfortunate characteristic. While valued for low sulfur content, they have relatively high mercury levels. Much of the coal from Illinois is just the opposite. Federal restrictions on mercury emissions have been bouncing around for a long time and are likely to bounce for some years to come, although individual states are tighter. Sulfur dioxide is more defined, so utilities tend to deal with that first. (Something to think about if you’re hoping the EPA can restrict carbon emissions.)
Mercury, sulfur dioxide, and most other pollutants (other than carbon dioxide) have mature technologies for abatement. It’s not all that hard to reduce mercury by 80% using a combination of flue gas temperature management and powdered carbon injection. A number of plants in Illinois are installing that technology to meet state regulations. These things can be fixed, or at least most of them. It just gets more expensive.