Thermoelectric generator keeps furnace running.
Thermoelectric generator technology promises to keep resident running even during an extended total electrical power outage. Feasibility of this concept was demonstrated by tests of a quarter-scale unit developed by Lionel Levinson and his associates at the General Electric R&D Center, Schenectady, NY, under contract to Rochester Gas & Electric (RG&E).
RG&E instituted the program after a March 1991 ice storm knocked out overhead power lines and left 200,000 customers without electric power for several weeks under severe cold weather conditions. RG&E chief engineer Bruce Snow concluded that a possible solution might involve use of a solid-state thermoelectric generator that generates electricity from heated gas.
"Because natural gas lines are rarely interrupted during a power outage, the furnace is still a potential source of heat," Snow notes, "but only if there's some way to supply electricity that's independent of the grid."
According to the Seebeck effect, discovered in the 19th century by German physicist Thomas Seebeck, an electromotive force is generated at a junction of two different metals in a circuit, when one metal is kept at a higher temperature than the other.
This phenomenon is already used in deep space power, in remote microwave relay stations, and for cathodic protection for bridges where an electric potential is applied to prevent corrosion attack, Levinson told R&D.
The GE design employs two thermocouple components for the junction: one made of an alloy of lead telluride with additions of tin and other dopants, the other of a silicon-germanium alloy. The heat from combustion of natural gas is applied to one element while a coolant--circulating air or water--keeps the other one at a lower temperature.
"You should view this in a cogeneration context where the electricity generated is the topping cycle and the heat to warm the house is the bottoming cycle," Levinson says. "We envision this as not just an emergency technique, but also as a way of running a furnace permanently without going to the grid. The system would be in place all the time to provide electricity for running blowers, controls, and sump pumps. In the 1991 outage, some homes were flooded but had no power to run pumps, which the new design could do."
A full-scale unit is planned to run in 1993. After that, RG&E may set up a consortium with manufacturers to design prototypes.
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|Publication:||R & D|
|Date:||Jun 1, 1993|
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