According to rough estimates from EPRI, corrosion costs the U.S. electric power industry between $5 billion and $10 billion each year. In steam generating plants, for example, EPRI estimates that half of all forced outages are caused by corrosion. Moreover, corrosion can increase the cost of electricity by more than 10 percent.

One way to solve the problem is simply to change your bacteria. Under normal circumstances, the metal surfaces at a power plant become colonized by microbes when the metal is exposed to process waters. Over time, these colonies merge to form a biofilm (well, slime), which is usually damaging: Sulfate-reducing bacteria can cause pitting in most alloys, even corrosion-resistant metals such as stainless steel and aluminum. But biofilms can be engineered to have a protective effect. Certain aerobic (oxygen-loving) bacteria can consume oxygen that would otherwise oxidize the metal, providing as much as a 35-fold decrease in the corrosion rate of mild steel and significant decreases in aluminum and copper corrosion rates.

On top of that, the bacteria can be genetically engineered to release antimicrobial substances to deter the colonization of sulfate-reducing bacteria.

"Wherever there is water, there are bacteria in the form of a biofilm, which is difficult to eliminate," said researcher Thomas Wood of the University of California at Irvine, an EPRI partner in the bacteria research. "Biofilms are not just slime-they have a distinct architecture, and the colonies signal one another. Why not have these biofilms work for us and be protective?"

A single type of engineered bacterium will not fit the bill, according to Wood. The most likely scenario is that researchers will take a sample of bacteria at a specific site, give them the genes to manufacture antimicrobials, and then reintroduce them.

The first testing site will be a cooled-water system on the Irvine campus, but several power plants are planning to participate in the study.



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