By Michael F. Carmichael
May 5, 2011
How can an electrical generating plant that burns coal and wastes about two-thirds of its energy possibly be considered “green”? When that waste energy is used to heat or cool thousands of office workers and apartment dwellers who keep warm or cool by way of a district energy system.
In a previous article, Corp! discussed briefly how a district system was providing heat and air conditioning to many of the buildings in Detroit’s Entertainment District as well as others in its downtown core. Instead of each building having its own capability to provide an appropriate temperature range for its tenants, steam, hot or chilled water is created at a centralized plant and sent to each client facility through an underground piping system.
| Downtown district cooling systems have been built in North American cities including Toronto, Ontario and other Canadian locales as well. |
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There are hundreds of these district energy systems across the world, serving not only downtown office and other buildings but also large college campuses – some with as many as 200 buildings including classrooms, administrative areas and residential housing units.
More than three-quarters of these districts use natural gas as the primary material to power the machinery needed to heat and cool the hundreds of thousands who benefit from these centralized operations. Coal provides about 15 percent, with the remaining fuel sources coming from industrial waste, biomass or other sustainable resources. Unlike individual buildings with a permanently installed heating and cooling system, a centralized district energy system often has the ability to use alternative sources when necessary – whether to moderate market price or supply fluctuations – yet another plus for their clients.
The idea of district energy goes back to Roman days but, in Detroit for example, it dates back just to 1903. There, giant tunnels were dug some 80 feet below the surface, lined with brick, then filled with some of the total of 39 miles of pipe that carried steam generated from the original plant – still operating, by the way – out to municipal and private office structures.
Today, says Victor Koppang, CEO of Detroit Thermal the current operator of the system that serves nearly 150 properties – including Ford Field, the domed home of the Detroit Lions, some 75 percent of the energy used comes from the combustion of industrial and commercial waste in a government-certified “renewable resource” facility – more commonly known locally as “the incinerator.” In the coldest days of Detroit winters, says Koppang, “the original plant uses natural gas to augment the steam supplied by the main plant.”
| Victor Koppang, CEO of Detroit Thermal. |
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Koppang points out that having individual heating and cooling plants in each customer building can be expensive. “There’s the initial cost of the boiler and the infrastructure supporting it; while at the same time there’s no need for space to house the equipment; there’s thus no need for licensed on-site boiler operators, or insurance to cover an individual system. There’s still the cost of natural gas to run it and regular maintenance to keep it running. Many of the licensed operators, by the way, come from the U.S. Navy – and you have to have at least four of them because there has to be coverage 24/7.”
“I tell individual building owners who are considering installing their own system,” Koppang continues, “‛why do you want to be in a business that’s not your core business and when you get it all purchased and installed, as soon as it gets bolted down, it begins to get old?’