In chemistry lab work the student gets to see first-hand how the science of life really works. He learns that every reaction must be balanced, that is to say that at the end of every chemical process there are three entities to consider;
- The spent products of the reaction
- Enthalpy, or the amount of energy, heat, given off or consumed in the reaction
- The end product
In the college lab of course, the amounts of these entities are small and can easily be absorbed into the air, and disposed of in the trash and sinks. In full scale industrial production however, each of these entities can be quite large and generally require significant technology and infrastructure to handle.
The casual observer, not usually being a scientist or engineer often judges technology only by assessing if the end product is desirable or not. When it comes to so-called clean energy and green technologies, this type of analysis is dangerous and sets us up to celebrate the wonders of today’s end product, only to suffer the horrors of the hidden side of the process decades later.
The tragedies associated with Thalidomide, DDT, and Asbestos are just a few examples of how looking only at the end product benefits have come back to haunt us in later years.
Nowhere is this end-product myopia more in play than my hometown Memphis where the TVA is leaning towards cooling the turbines of a new Combined Cycle Energy (CCE) plant by taking water out of the Memphis Sand Aquifer. I have already written a piece called “Whose Water Is It” that addresses water rights, but what I want to talk about here is the push-back TVA is getting from environmental and conservation groups.
For fear of depleting the drinking water source, many are claiming that TVA can simply use Mississippi River water, or industrial gray water to cool the turbines. On the surface, simplistically this sounds reasonable. “Take the junk water and leave the good stuff for us”.
When we inject science into this argument however, the well-meaning citizen comes to find out that what he is suggesting is actually not Green, and anything but good for the environment.
The cooling of turbines requires very clean water. If the water is dirty and causes deposits, those deposits cause the spinning turbines to become unbalanced, and just like a spinning car tire, undue stress on the mechanical parts will lead to expensive failures.
Can Mississippi river water be treated to be compatible with cooling turbines? Of course it can. However, the river water will have to be treated, and that treatment is not environmentally pretty;
- First the pH will have to be adjusted with caustic soda and aluminum coagulants so that the dirt forms clumps and sinks to the bottom of a clarifying filter.
- That toxic sludge will have to be sent to land fill, transported I might add by fossil fuel-burning vehicles.
- Once clarified, the pH will have to be normalized with hazardous acid.
- The clarified water will have to have any iron oxidized, most likely using large doses of chlorine.
- Once the iron is removed the water will require softening. This will consume immense amounts of salt and put immense amounts of chlorides back into the environment.
- Remember also that treating river water will require 200% the required energy for pumping. The water will be pumped first to the clarifier, which is an open filter that works on gravity. Once clarified the water will again have to be pressurized to send to the subsequent filtration steps.
The take-away here is that while well-intended, many times the emotional nature of environmental stewardship, when not originating from a scientific starting point, can do more damage to the environment than good. In the case of using river water to cool a CCE plant while there is much cleaner water readily available, this would be one of those occasions.