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District heating: new-old energy saver lets city be your central heating

District heating. Hardly words to set the world on fire. Nevertheless, mayors and scientists across the country are warming to the idea of reigniting this 19th-century heating method as an answer to 20th-century energy demands.

Used since 1890 to heat several cities across the country by interconnecting steam pipes, district heating is currently enjoying a fresh boost of support as several European cities have successfully replaced the old steam technology with more efficient hot water systems.

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By heating several acres of high-density dwellings with miles of underground piping connected to a few centralized heat generators, fuel efficiency is greatly improved over the traditional individual furnace method. The energy-saving system is proving particularly attractive to US cities in the frost belt.

In addition, the federal government is throwing in $1.5 million worth of research money to help 28 communities from New York City to Santa Anna Pueblo, N.M., develop hot water district heating systems to cut fuel costs.

The proposed benefits include:

* Cuts in energy costs for both the city and the individual -- up to 40 percent in some cases.

* The possibility of using many heating fuels -- coal, oil, natural gas, nuclear-power, even trash to warm the hot water pipes.

* The ability to capture waste heat from a city's electrical generators -- a jump from 40 percent efficiency to 80 percent in most instances. Although some cities, such as St. Paul, Minn., plan to use this cogenerational technology for district heating, others are considering building simpler heat-producing plants.

* Curtailment of pollution levels by gradually eliminating individual furnaces and chimneys.

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* The increase of long-term, low-skill jobs required for installation and maintenance.

"District heating is the best kept secret I've seen in a long time," says Mayor Winfield Moses of Fort Wayne, Ind. "It provides a real opportunity for a cost-effective energy solution."

The great enthusiasm for district heat voiced by mayors and scientists is tempered by the reality that implementing such a system must be an evolutionary process. "This is not a solution that is going to develop rapidly," says Mayor Francis Duhey of Cambridge, Mass.

Although the US has used district heating since the turn of the century, the system currently supplies less than 1 percent of total US energy demands. And most of the systems in the 40 cities across the country that still rely on the old-fashioned steam pipes have fallen into disrepair.

"The old steam systems have atrophied," says Housing and Urban Development program officer Windham Clark. "They're giving district heating a bad name." Indeed, many observers admit the best markets for the new hot-water heating systems are those cities without previous district heat experience.

Another obstacle to mass conversion to district heating is the huge amounts of initial capital required to install piping and convert buildings and generators to the new system.

"The real problem is getting the institutions involved financially," says James powell, a senior nuclear engineer with the Brookhaven National Laboratory. "It's a capital-intensive program."

Not only must the cities appropriate large amounts of funding to install the piping, utility companies also must invest in the multimillion-dollar conversion of generators. In addition, city dwellers must finance their part of the conversion. Paybacks on the original investment, however, are said to be shortterm -- less than 10 years in most cases, after which the savings begin to accrue.

One way to surmount the huge financial investment is to start with a small system -- one or two heat sources and a limited number of users, and apply the first revenues toward enlarging and extending the heating network. Cities in West Germany, Denmark, and Sweden are operating efficient and effective district heating systems that started on such a limited basis.

Of all the US cities, St. Paul is most near to implementing the nation's first new district heating system. With some federal block grant funding, the city is embarking on converting its entire downtown area by fall of 1982. The local utility company has already appropriated $6 million for its generator conversion. And the city is busy finding the nearly $35 million it will need to buy and install the miles of piping.

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