Troy in New York state is one of the first cities to use an innovative type of heat pump.Credit: TW Farlow/Getty
The half-a-dozen nineteenth-century commercial buildings huddled beside the Hudson River that make up an arts centre in Troy, New York, are destined for a distinctly twenty-first-century energy makeover. The same goes for an apartment building across the street and a department store-turned-technology hub a few blocks away.
The plan — hatched by Troy’s economic-development office to revitalize the downtown area and now driven by regional utility company National Grid — is to combine the buildings’ heating and cooling systems in a single high-efficiency, low-carbon network. The hope is that more buildings will join the scheme before the thermal network begins operating in 2027. Ultimately, it might wean all of the Central Troy Historic District off natural gas.
Heat pumps installed in the buildings will do most of the work. But these are not the same heat pumps commonly used to maintain the temperature of individual homes and businesses. Those devices warm indoor spaces by extracting heat from cold air, and cool them by pushing heat out into already hot air. In Troy, a once-prosperous industrial city about 200 kilometres north of New York City whose manufacturing economy collapsed, the new heating and cooling system will work quite differently.
Nature Outlook: Cities
Behind the Arts Center of the Capital Region, dozens of boreholes are set to be drilled 150 metres into the ground, where the average temperature is 13 °C all year round. In the Hudson Valley’s increasingly scorching summers, the network’s heat pumps can dump heat into the cooler bore holes. And on freezing winter nights, the pumps will keep residents warm by drawing heat from the relatively warm ground.
The thermal energy networks (TENs) that tap geothermal resources in this way are radically changing the image of a technology that utility companies had previously dismissed as prohibitively expensive. “Geothermal would be written off on day one,” says Eric Bosworth, an independent energy consultant in Hopkinton, Massachusetts. “Now there are examples of successful projects all over the place.”
More than 100 of these systems already operate in relatively carbon-conscious Europe, where they are usually called fifth-generation district heating and cooling (5GDHC) networks. There are more than 50 in Germany alone, where installations are accelerating to eliminate the country’s dependence on Russian gas. In North America, the first TEN built by a US utility company began operating last year in the city of Framingham, Massachusetts. More than 20 others are either operating or in development in New York state, including in Troy, and in other cities, such as Boston in Massachusetts, Chicago in Illinois and Toronto in Canada.
Proponents of TENs say that the technology’s efficiency could accelerate a transition from natural gas and ease the demand on power grids. But the technology needs extensive research and development to meet its full potential. The design varies from place to place, and some overly conservative choices are pushing up costs. “There are still no good official or even unofficial design guidelines,” says Marco Wirtz, founder and chief executive of district-energy modelling firm nPro Energy, based in Düsseldorf, Germany. “Engineers are learning as they do.”
Drilling down
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