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Emergency Power with Spinoff Applications Combined Heat and Power Systems Make Sense for Multi-Res
November, 2007
By Danny da Silva
Anyone living in Ontario or the U.S. northeast in August 2003 will likely remember dark residential towers and office buildings during the power blackout, which affected 10 million people. While most people experienced only minor inconvenience of being without power for a few hours, others went without power or water for several days. For some elderly people and/or those with medical conditions making them heavily dependent on electrical power, the blackout was a serious problem.
During the blackout, backup generators including those on tower roofs sputtered into life, but they were not able to meet much of the potential load. Concerns about another blackout means that for some members of the buying public they find the assurance of reliable power a major attraction.
Although it may not have the sales sizzle of a marble countertop or a rooftop pool, reliable power can appeal to many potential customers. Changes in technology are making it more possible for multi-residential developers to offer reliable power from on-site generation as a differentiator. An added extra may come in lower operating costs that translate into lower utility bills for unit-holders.
Recent technology makes it possible to develop gas-fired generation capacity that meets the complete power needs of a building, does not disturb residents with noise or vibration, and requires low maintenance. Combined heat and power (CHeP) systems divert the auxiliary power system's excess heat for use in heating the building, and meet the building's power needs as well.
Traditional emergency power systems generally use diesel generators and might operate 24 to 30 hours per year - meaning a great deal of capacity and investments sits idle most of the time. Even with an on-site storage tank, it will likely have only about 24 hours' worth of capacity. Also, it will be sized to meet only a partial power load, meaning that while residents indeed have reliable power, they still suffer some inconvenience. These systems are also fairly low efficiency in converting fossil fuel into electricity.
Recent improvements in small-scale gas-fired engine generators mean that gas power is an increasingly viable alternative. Gas-powered CHeP systems can be sized for full power load, so that residents' lives are not interrupted - which, for some, is more than just a convenience factor but is health-preserving and even life-saving.
No on-site storage tank is needed, which means simpler operation and less capital investment. It also requires less space and there is no need for truck deliveries of fuel.
Higher efficiency means that more fossil energy is converted to electricity. As a bonus, excess heat from the system can be recovered and cycled into the building's heating systems, reducing costs.
The cost-effectiveness of gas turbine generation means it can be, at times, a lower-cost source of electrical power than the electrical grid. Automated start-up and operation, coupled with software systems that check the relative prices of gas and electricity, allow a complex to switch back and forth between the two sources of electrical power. In this way, the gas-fired CHeP system moves from being emergency power to, in effect, co-generation of power.
Gas turbine generators have also made advances in noise and vibration control. Better ways to dampen vibration and isolate equipment from the surrounding building make these systems less disruptive. Better shielding, attenuation and other measures from the acoustic engineers' box of tricks makes them quieter.
It is likely that gas-turbine CHeP will be, at least initially, most effective in buildings targeted at seniors, for whom reliable power is often a medical necessity, but the appeal is spreading to a wider range of markets.
Danny da Silva, P.Eng. is a member of the Noise group at Golder Associates Ltd. He can be reached at tel. 905-567-4444; dandasilva@golder.com or noise&vibration@golder.com.
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