What could air conditioning possibly have to do with black drum? The two subjects may seem as unrelated as hurricanes and butterfly sneezes, but in Florida’s web of action and environmental reaction, there’s a connection all right.

Most of the electricity that runs your grumpy old AC comes from a steam-powered generator. The heart of the system is a heat source, either a fossil fuel-burning furnace or nuclear reactor. Here, water in a hundred-plus-mile network of tubing (or boiler) is cooked at 2,000-plus Fahrenheit, producing steam. Pressurized as it travels through more tubes, the steam ultimately rushes across the fan-like blades of a turbine, which propels an electromagnetic generator. Watts are delivered to your neighborhood—lots and lots of watts come summer.

So where’s the fish figure into all this?

To keep the generators spinning at max efficiency, steam passes through the turbine, then it’s exposed to a cooling source, or condenser, and recirculated. The condenser, another network of pipes, uses its own supply of water—a steady flow, often in the hundreds of millions of gallons per day. That’s known as once-through cooling.

If the condenser drinks from a biologically rich source, like an estuarine bay, whatever’s living in the water has to contend with the possibility of getting sucked into the system. Large fish, turtles and marine mammals can usually swim away from the tractor-beam intake structure, but smaller, slower-swimming critters might get pinned against a debris screen, and drown. That’s termed impingement.

Very small organisms—microscopic plankton, gamefish eggs and larvae—are frequently pulled right on through the system. Their vast numbers are sloshed around, chlorinated, superheated and discharged in an endless broth of dead organic matter. That’s entrainment.

In the late 1970s and early ’80s, the federal Environmental Protection Agency (EPA) required many power plants to document the organisms impacted by once-through cooling. In 1972, Congressional amendments to the Clean Water Act, section 316(b), directed the EPA to regulate cooling water intake structures to “minimize adverse environmental impacts.” Data collecting went on for years, but only in the last couple years—after prodding by environmentalists—has EPA done much regulating.

One of Florida’s largest generating plants is the Tampa Electric Company (TECO) Big Bend station, situated on Tampa Bay, at Apollo Beach. Big Bend provides a telling case study in impingement and entrainment, or I&E. Consultants found that annually, impingement resulted in the loss of 419,286 “age 1” equivalent fish, and 11,113 pounds of fishery yield (age 1 equivalent is a statistical way of converting loss of fish eggs and larvae into numbers of year-old individual fish. Fishery yield loss means pounds of fish that won’t be landed due to I&E losses).

Entrainment was far more lethal: 7.71 billion—Billion!—age 1 equivalent fish were being decimated; 22.8 million pounds of lost fishery yield. Most heavily hit were bay anchovies, but the list included other valuable organisms like stone crabs, pink shrimp, seatrout, herring...and black drum.

I wondered about those drum. The Big Bend plant, with all four generators humming, can supply enough electricity to power about 170,000 households. Entrainment data showed Tampa Bay could be short 5.2 million black drum each year. I did a little math, and the figure that emerged was pretty scary:

In theory, the electrical demands of a single household could wipe out 30 black drum in a year.

Dial down your AC in August, catch fewer drum next March.

It doesn’t have to be that way—and in fairness to the TECO people, the two newer (post 1975) generators at the Big Bend plant have been equipped with fairly effective marine life barriers.

I visited the Big Bend plant as a guest of David Lukcic, Manager of Land and Water Programs, Environmental Health and Safety. Wearing hard hat and protective goggles, I got a look at what happens to critters vacuumed into the cooling water intakes at Apollo Beach. It was more or less an industrialized water park for plankton.

Rectangles of .5 mm mesh, arranged five-across in a long conveyor, circulate through the incoming water stream. A trough at the bottom of each rectangle catches organisms that fall off; what sticks to the mesh is blown into the trough by pressurized water, near the top of the conveyor. The troughs dump into a waterslide, for lack of a better term, which winds down to a sump, and ultimately flows to the plant’s warmwater outfall canal.

The EPA notes that these “fine-mesh traveling screens” at Big Bend have achieved an 86 to 95 percent reduction in entrainment (a certain percentage of creatures don’t survive the waterslide, so it’s more accurate to say 66 to 93 percent survival).

Why haven’t these devices been installed on the other two intakes at Big Bend?

Lukcic was candid in his answer: “We were not required to. Those intake structures were permitted in the 1970s.”

Retrofitting the older intakes would be costly, Lukcic explained, but that’s just what TECO may have to do when its 5-year National Pollution Discharge Elimination System (NPDES) permit comes up for renewal in 2006.

In February 2004, EPA published final regulations for Phase II rule-making under 316(b). The regulations will require large existing power plants using once-through cooling systems to reduce impingement by 80 to 95 percent from uncontrolled levels, and entrainment by 60 to 90 percent.

“We’re currently studying our options,” said Lukcic.

There are 27 plants in Florida affected by the 316(b) regulations, according to Allen Hubbard, Supervisor for Power Plant NPDES Permitting with the Florida Department of Environmental Protection (DEP). In 1995, EPA granted NPDES permitting authority to the Florida DEP. Hubbard and his staff review permit applications, deciding whether they’ll meet EPA standards.

One Florida facility currently up for permit renewal is the Florida Power and Light Cape Canaveral Plant. It’s a mid-sized, oil- and natural gas-burning facility on the Indian River near Titusville. On average, its condenser system siphons some 664 million gallons of Indian River water per day, or the equivalent of more than 664 Olympic-size swimming pools. (TECO Big Bend draws twice that). That’s every day.

In Florida, a power plant must give public notice when a draft NPDES permit has been issued; DEP then coordinates a local public information session, and invites public comment. Related government agencies such as the Fish and Wildlife Conservation Commission and U.S. Fish and Wildlife Service, are also contacted.