Nuclear Power's Climate Protection : Water-Use Tradeoff
Most non-natural gas electrical plants use steam to drive their turbines. After superheated steam makes a pass through the turbines, the discharge is condensed, and then recycled back to the hot end of things for another pass through the turbines. Cooling process choices will be very important in coming decades because of the prospect of many "clean coal" or new nuclear plants added to counter climate change. At the heart of the issue is water consumption in a supply-constrained world. Background for non-engineers: -- there are three ways to cool these plants; two wet, and one dry. The wettest way is to withdraw surface water from ocean bay, lake, pond, or river, and pass it through a secondary cooling loop. The one-pass cooling withdrawls are the least aquatic-life friendly, which we'll detail with an example after the fold.There's a variation where a man-made pond is discharged to and recycled from. The other common wet method, much more costly than one-pass withdawl, is to build a bank of evaporative cooling towers, an example of which is shown here. The towers evaporate much water, need a water purification system up front, use biocides to inhibit fungal and algal growth on the tower media, create a fog-laden microclimate, and stab at the horizon. The third method is to use dry (air) cooling towers, which are expensive, less "proven" and more suitable for biomass or coal fired plants than nuclear. Guess which method those twenty new nucs per year or "clean coal" plants would most prefer to use?
The Post-2000 generation of nuclear plants will have plenty of design innovations. The first licensed will be 'prototypes', although you'll not hear the word "experimental" at a public hearing. The last thing designers will want to do is add unnecessary complexity and cost to a "new design." So, they'll almost certainly go for 1-pass cooling water withdrawl when there's plenty of water to be had.
Layer upon this added water consumption Western states mired in extended drought, Mexican farmers bankrupted for lack of water, seriously overtapped aquifers in the grain belt, coastal and Great Lakes fisheries stressed by habitat destruction, a growing population, competition with hydroelectric power plants and you get the picture. By avoiding the cooling water issue, the "clean coal" and new nuclear options can look pretty good. Put it on the table for all to see and water will become a powerful issue for local opponents.
To get an idea of what is at stake, we've included, below, a few excerpts from a recent Asbury Park Press story (subscription only) regarding cooling methods at New Jersey's Oyster Creek nuclear plant site.
Feb 15, 2006 - Asbury Park Press, N.J. "Can the Oyster Creek nuclear power plant afford to install costly cooling towers, or would the plant close to avoid the expense? State environmental officials want towers to be built to preserve aquatic life from Barnegat Bay, but the plant's operator, AmerGen Energy Co., said they are costly and unneeded...In a 2004 meeting with DEP officials, managers with Exelon, which owns AmerGen, said cooling towers, if required, "would cost $25 million to install and would result in Oyster Creek no longer being financially viable," according to the DEP.
Oyster Creek, which began operating in 1969, withdraws about 1.3 billion gallons of water a day from an intake canal linked to the South Branch for cooling, according to a DEP fact sheet. The water intake and discharge system kills millions of small fish, shrimp and other aquatic species each year, according to estimates cited by the DEP".
NOTE: to avoid a visit from Homeland Security (money wasting bureaucrats) we have refrained from posting here any aerial photos or identifiable building pictures (gutless TreeHuggers). That's a shame because only by looking at such images can you get an idea of how important water consumption is to large scale power production (out of sight, out of mind). Ideally, we'd have included a false-color infrared satellite picture showing thermal pollution from hot water discharge plume. We'll just have to close our eyes and imagine (cryptome).