Engineering Expert Witness Blog

     Are you familiar with the adage, “Things are not always as they seem”?  It’s probably come into play in your life at one time or another, like when you opted to buy the cheapest model of something, only to find out that its life span was two weeks before falling apart.  Not such a bargain after all.

     Well, it’s kind of that way with low sulfur coal and its application in electric power production.  All coals contain some sulfur, their content ranging from trace amounts to as high as 8%.  This sulfur ends up as a byproduct of the combustion process, meaning it is released into the atmosphere when coal is burned.  There it combines with moisture in the air to form sulfuric acid.  If you will remember from last week’s blog, this is the stuff that forms acid rain, able to dissolve marble statues, corrode metal, and disrupt eco systems.

     In the process of generating electricity for homes and businesses, many utility power plants of the past burned coal with high sulfur content.  This was the case through the middle of the 20^th Century.  This coal was brought into power plants by trains and river barges from nearby coal mines.  In some cases power plants were actually built next to the mines, thereby eliminating shipping cost.  It was effective and cheap.

     Then, in 1963, the Clean Air Act was signed into law, its purpose to improve, strengthen, and accelerate programs for the prevention of air pollution.  By 1970 the Act had empowered the federal government to set and enforce national air quality standards for sources of air pollution, like coal burning power plants.  Under the Clean Air Act, government was able to mandate to utilities that they reduce sulfur emissions or face court injunctions to shut them down.  Caught between a rock and a hard place, utilities learned to comply, switching over to lower sulfur coals.  But the story doesn’t end here.  That lower sulfur created a whole host of new problems, for the power plant and their consumers.

      To begin with, low sulfur coals are scarce in areas of the country where electricity is needed most, like the densely populated eastern half of the country.  It has to come from mines in the western states like Wyoming, and for a power plant located in Chicago, for example, this can get costly.  A lot more costly than simply getting the coal, high sulfur content coal, that is, from nearby mines in southern Illinois.  The result is higher transportation costs, and this cost is passed on to consumers.

     Another problem with low sulfur coals is that they tend to release less heat energy than higher sulfur coals when they are burned.  That means that you have to burn more of it to generate the same amount of power.  As a result, utilities ended up having to buy more coal, another cost that was passed on to the consumer.

     Yet another issue with the switch from high sulfur to low sulfur coals involved the reconfiguration of power plants that was made necessary.  You see, when power plant boilers are designed, they have a particular type of coal in mind, and that originally was high sulfur coal.  In addition, many power plants have been required to install equipment to scrub sulfur from the gases produced when the coal is burned.  This scrubbing equipment is expensive to purchase, install, and operate.  Pollution control equipment like this consumes power, but it does not facilitate the process of generating electricity.

     In addition to these costs, the switch to low sulfur coal causes many other problems that can raise the cost of operations and make the power plant less reliable.  For example, some low sulfur coals have properties that tend to make ash stick to the surfaces inside of boilers, often leading to boilers overheating and springing leaks.  If these leaks are bad enough, the boiler has to be shut down for cleaning and repair, and when this happens the electrical generating unit has to be taken off the utility grid.  The net result is less power being available to meet consumer demand.

     We can thank the Clean Air Act for effectively reducing the amount of airborne pollutants, but we must acknowledge the cost to do so.   Electric utilities are for-profit corporations, not charities, and someone has to pay for the increased coal consumption, higher transportation costs, equipment additions, and operating problems that are a result of the usage of low sulfur coal.  That someone is the consumer.

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