Many people know that power plants are a major source of air pollution and greenhouse gasses ; however, few are aware that many of those same plants kill and injure fish and other aquatic life. Power plants – both nuclear and fossil-fueled – with antiquated “once-through” cooling systems withdraw massive amounts of water from rivers, lakes and estuaries to cool the steam used to create electricity. These withdrawals, which add up to about 135 trillion gallons per year nationwide, kill trillions of fish and other aquatic organisms, particularly small, fragile eggs and larvae, altering the aquatic food chain and ecosystems.
These “thermoelectric” power plants boil water to produce high-pressure steam that turns turbines, producing electricity. The steam is then cooled by a condenser which typically uses water drawn in from a nearby lake, river or estuary. In a once-through cooling system the cooling water is not reused, instead it is discharged at a higher temperature back into the water body from which it was withdrawn. To continue cooling steam, the power plant must constantly withdraw enormous amounts of new water, injuring and killing fish and other aquatic organisms in the process.
By modernizing existing power plants to cool steam with recirculated water - similar to how a car radiator works - rather than continually withdrawing more water, the harm to fish and other aquatic life is dramatically reduced. The “Best Technology Available” to end this environmental destruction — closed-cycle cooling — reduces power plant water intake by approximately 95 to 98 percent, thereby reducing the destruction of aquatic life by 95 to 98 percent.
There are two main types of closed-cycle cooling technologies. In a wet closed-cycle cooling system, water is first circulated through the plant to absorb heat, and then moved through the cooling towers to release heat to the atmosphere, primarily through evaporation. The condensed water is then recirculated through the plant. A dry closed-cycle cooling system uses air flow, rather than the evaporation of water, to transfer heat from the power plant.
The simple, proven solution to ending the destruction of aquatic life by once-through cooling systems is clear, yet nearly 500 power plants nationwide continue to rely on this outdated cooling technology.
Installation of closed cycle cooling can be accomplished as a retrofit to a power plant while it is shut down for a period of time. A more cost-effective installation process is through repowering, which happens when the plant’s old, inefficient and polluting equipment is replaced with newer, lower emissions equipment. Repowering can be done in at least two ways:
While repowering might be suitable in some circumstances, for those power plants that are borderline profitable, retirement might be a better option. Replacing aging power plants with more efficient generation, including investing in clean, renewable energy production and energy efficiency, will help to restore the nation’s rivers, lakes and estuaries while cutting emissions of carbon dioxide and other greenhouse gasses.