'Recycling' Energy Seen Saving Companies Money
Have you ever taken a really close look at a smoke stack rising from a factory or power plant? Tom Casten does, even when watching a TV show like The Simpsons.
Casten surveys a picture of the fictional nuclear power plant where Homer Simpson works in his cartoon hometown of Springfield. "What you see is two giant structures, they're cooling towers. ... Giant amounts of steam coming out of the cooling towers basically reflecting that two out of three units of energy are basically being thrown into the air as waste heat."
For every three units of fuel — like coal, natural gas or oil — that are burned to make electricity, two are lost in the process, most of it as waste heat that just drifts away, says Casten, who is chairman of Recycled Energy Development, a company that works with industrial clients to capture waste heat to produce clean electricity.
Casten sees waste heat everywhere, not just in cartoon power plants, but at factories, mills and refineries all across the country.
With rising fuel prices taking a bigger bite out of the profits of the nation's manufacturers, Casten says many of them could save a lot of money, and reduce greenhouse gas emissions, by capturing that waste heat and recycling it to produce power.
"There are many industrial processes that emit high-temperature exhaust," he explains. "You can use that high-temperature energy to boil water, make steam, and drive an electric generator."
For 30 years, Tom Casten has been developing and selling the technology to recycle energy. Before starting Recycled Energy in 2006, he served as CEO for Primary Energy Recycling Corporation, which has several energy recycling projects in place at the giant ArcelorMittal steel mill in East Chicago, Ind.
Standing on a platform some 200 feet up, high above the sprawling steel mill's vast complex on the shore of Lake Michigan, John Prunkl, president of Primary Energy Recycling Corporation, points to a battery of coke ovens below, that stretch at least a quarter of a mile long.
"There's a lot of heat down there," Prunkle says. "Coke is coal that's burned in an oxygen-deprived environment. And when you do that, you create and release a tremendous amount of heat. [It's] very hot, probably 2,500 degrees."
This excess heat used to just drift away. In 1998, ArcelorMittal, a European-based company, contracted with Primary Energy to install 16 boilers above the coke ovens. Those boilers capture the waste to generate steam, which turns turbines to make electricity.
"We can produce almost a hundred megawatts of electrical generation out of the steam that's produced off the waste heat that we're capturing here today."
That's enough electricity to power more than 60,000 homes, according to Department of Energy Statistics.
Recent EPA and DOE studies suggest U.S. industries waste enough heat to generate an estimated 200,000 megawatts of power — nearly 20 percent of what this nation uses. That's enough electricity to replace up to 400 coal-fired power plants.
And it's not just excess heat that can be recycled.
In another part of the ArcelorMittal steel mill, waste gas from the blast furnace is captured and re-used. The waste gas usually is just burned off by a flare at the top of a stack, but when mixed with oxygen, it can be used instead of purchased natural gas.
"We're taking a gas, waste gas, that would have been flared into the atmosphere, we're creating steam, using that steam for a variety of purposes, obviously to drive the blast furnace and to create power," says Tom Riley, ArcelorMittal's manager of utilities for the steel mill. Riley says that energy recycling can generate 65 to 70 megawatts of power.
And here's another way the plant recycles energy: That waste gas leaves the blast furnace at a very high level of pressure, 30 pounds per square inch (PSI). The waste gas' pressure has to be lowered to three PSI to burn, so Riley says they've recently equipped the blast furnace with a recovery turbine to utilize the huge amount of energy produced by such a big drop in pressure.
"We put a turbine into that gas stream, the turbine spins, basically taking that pressure drop, drives a generator and we're making on average about 16 megawatts of electric power," Riley says. "That's the same as generating as eight wind turbines, big wind turbines, at full speed. No additional fuel at all, just taking advantage of the change in pressure, and no emissions."
Energy recycling creates about 250 megawatts of power at this steel mill. That's about half of the electricity it uses each day, the company says. In 2004, the total at this one steel mill equaled the total electrical output of all the grid-connected solar collectors in the world.
That's according to Casten, and the comparison shows that with the clamor to go green and use solar and wind power, there's vast potential in energy recycling that is available right now. Energy recycling saves ArcelorMittal tens of millions of dollars a year in energy costs, and the company says it reduced carbon dioxide emissions by 1.3 million tons a year.
This type of energy recycling is commonplace in Northern Europe and Japan (it's one of the reasons ArcelorMittal is actively utilizing the technology in its U.S. plants). Denmark generates close to 55 percent of its electricity this way. In the Netherlands and Finland, the figure is closer to 40 percent, and in Germany it is 35 percent. But in the U.S., energy recycling accounts for just 8 percent of the nation's electrical power, according to the U.S. Department of Energy.
So why isn't it done more often here?
"The real challenge is that it's typically illegal," says Casten, "and you've got to find a way around the laws."
Casten says state and federal laws protect monopoly utilities, often preventing energy recyclers from selling excess power back to the grid or from running power lines across a street. Even the Clean Air Act prevents utilities themselves from recycling waste heat at older coal-fired power plants, because any modification subjects them to newer regulations.
But with soaring energy costs and an increasing push for green power, Casten and others hope recycling energy can start to get as much attention as solar panels and windmills.
"We think we could make about 19 to 20 percent of U.S. electricity with heat that is currently thrown away by industry," he says. "This electricity is just as pristine as making it with a windmill or making it with a solar collector — no additional fuel, no additional pollution. Just a little bit of additional brains."
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