Take a jet engine hooked up to some big magnets, add some steam pipes, and what do you have? The comeback of some old-school technologies that could help solve our modern energy problem.

The idea is simple — generate both electricity and heat in the same place, but the potential benefits are big.

Unlike a traditional electric power plant, which can convert about 40 percent of its fuel into electricity but wastes the rest as heat, these combination plants capture that heat and use it to warm or cool buildings. The efficiency of combined heat and power plants can reach into the 80 percent range. If you hook up that plant to a network of steam pipes and electrical wires, you've got the tools to power an entire campus or community.

Combined heat and power, or CHP, could get a a push from possible climate legislation. And this week, the Department of Energy bet $156 million of stimulus funding on these steam-age ideas. It fits with industrial, commercial and municipal interest in reducing fuel costs and environmental footprints.

"We do a lot of work with large commercial and industrial concerns, both public and private, and CHP is really starting to gain momentum," said Brian Casey, CEO of SourceOne, the consulting division of environmental services giant, Veolia. "Ultimately as a country, if we get our act together here about how we regulate carbon, CHP will be a tool in that battle."

The United States could benefit by learning from its past. In fact, the very first central power plant, Edison's Pearl Street Station, produced both heat and power, but in the era of cheap, abundant energy, that idea was almost abandoned.

Today, most of the time, we make electricity and generate heat in different places. We get our electricity for lighting and power from a central station located far away and transmitted to us through the grid. Heating or cooling, on the other hand, is often accomplished with on-site boilers or electric radiators. Both systems work less efficiently when they stand alone. Together, waste heat generated during the process of making electricity can be scavenged and piped around to provide climate control.

In the early 20th century as our current energy system was being built, Americans "ignored the efficiencies of cogenerating electricity and steam heat at central plants in favor of less efficient oil and coal furnaces in each building," wrote energy historian David Nye. Heat and power got farther and farther apart.

Now, though, the century-old trend that accompanied the rise of electricity is being reversed. Many industrial and commercial entities are choosing to build their own combined heat and power generating facilities. In 1998, there were only 46 gigawatts of CHP facilities in the United States. By the end of 2008, 85 gigawatts of CHP capacity had been built.

A DOE report released late last year found that CHP was already responsible for reducing American emissions by 248 million metric tons of CO2, which is equivalent to taking 45 million cars off the road. That's a lot more than wind, solar or any of the other renewables. They have such a big impact because they effectively double the amount of work that we get from burning the same amount of fossil fuel.

With the extra impetus to reduce carbon dioxide emissions to combat global warming, these electric plants that also use their excess heat could experience a lot more growth over the next 30 years. To do so, though, they have substantial challenges to overcome.

For one, many of the regional benefits of CHP are not recognized by existing environmental and utility regulations. Utilities resist CHP systems because they complicate their transmission infrastructure and they say that's costly. And people have grown used to having their power generated in some far off place and often object to the installation of a power plant nearby.

Despite these hurdles, CHP proponents push on. Casey's team worked with Biogen Idec, a biotech firm in Cambridge, Massachussets, to install a plant at the company's new building. After protracted negotiations with the local utility, they are now on good terms, but it was no easy task.

The plant itself is a mini-technological marvel that will pay for itself with energy savings in just four years. It's essentially a jet engine (see photo above) hooked up to magnets located in the basement of an office building.

"It's subterranean, 30 feet underground. There's a beautiful mezzanine and atrium above it and the research scientists in offices," Casey said. "In the footprint of about 20,000 square feet is a combustion turbine.... It turns a generator to make electricity and then we grab all the waste heat we can with a heat recovery steam generator."

The electricity lights the building and the steam is used directly for heat or converted by absorption chillers for refrigeration. It doesn't produce all its own electricity, tapping into the local grid when extra power is needed. But that's not the only legacy network to which it's connected.

"This specific project is blessed that it stayed connected not just to the electric network but stayed connected to the district steam network," Casey said.

Though they are rarely noticed now, most of the big cities in America have some kind of subterranean steam system in place, a relic of the time when steam infrastructure was still being built. And heating whole chunks of cities together, in what are known as district energy systems, has environmental benefits of its own.

"By combining the thermal needs of hundreds of buildings, district energy systems deliver economies of scale for employing equipment and technologies that are far more efficient and versatile than for individual buildings providing their own cooling and heating equipment," argued Veolia CEO Oliver Barbaroux in a Forbes editorial. (Veolia operates more district energy systems in the United States than does any other company.)

The systems are basically a series of huge underground steam pipes connected to boilers at a central station. They can be a perfect complement for CHP systems when custom-built for an university like M.I.T. or the University of Florida or when a local steam system is available to tap into.

San Francisco is a great candidate for a CHP facility. A set of boilers is already located near Mint Plaza, a newly remodeled and trendy area of town. Around the corner from the nation's fanciest coffee shop (Blue Bottle's flagship store), two smokestacks rise 100 feet into the sky. They're part of a steam power system that stretches back 100 years.

On the map, you can see the steam distribution system as it existed in 1917. It's nearly the same today, except for a small, new line that runs to the enormous Westfield mall on Fifth and Market.

"There's still some of the original piping," said Wayne Wong, marketing manager for the plant, which is operated by Minneapolis-based NRG Thermal, a division of one of the nation's largest utilities.

The inside of the plant is probably 100 degrees and louder than an AC/DC show. The boilers are clanging away, supplying energy to 170 buildings with 37 million square feet of space in the city's downtown core. The photo below shows one of the main pipes that connects the plant to the underground system.

Right now, the plant only generates heat, but Wong said they'd like to put in a CHP plant that could produce 50 megawatts of electricity and continue to supply steam to their existing customers. It turns out, though, that hooking up the CHP system with the district energy system won't be easy.

"You know how it is, folks don't want power plants in their backyards," Wong said. "Even if the money was OK, just to get permitting would take years and years and years to overcome the opposition to it."

Perhaps, with the new emphasis on carbon emissions and local systems, more environmentally minded Americans will be willing to allow innovative fossil fuel power plants into their communities. Even though they burn fossil fuels, CHP and steam plants hooked up to district energy systems are more efficient than other solutions. They might use brown fuels, but they should make greens happy.

See Also:

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