Large power stations only rarely manage to convert more than 40 percent of the produced energy into electrical power. The rest is released unused, mainly via the cooling towers, into the atmosphere.
Researchers at the Fraunhofer Institute for Material and Beam Technology IWS in Dresden, have been working on using the potential lying dormant in the over 150m high concrete giants. The idea is to use thermoelectric devices fitted inside cooling towers, where there can be very large differences between the hot steam and cooler concrete skin under some circumstances.
Dr. Aljoscha Roch of the Fraunhofer Institute for Material and Beam Technology IWS in Dresden explains: "Thermoelectric generators (TEG) currently have an efficiency of around eight percent. That sounds very small. But if we succeed in producing TEG cost-effectively, on a large scale and from flexible materials we can install them extensively on the insides of the concave cooling tower wall. In this way, through the enormous amount of energy produced in the huge plants, we could generate large quantities of electricity".
The "not in my backyard" syndrome typically keeps these power stations away from highly populated areas where the excess heat could be used to heat buildings. Next best is efficient energy extraction at every stage in the system (from steam to hot water to cold water).
I agree with the "no free lunch" dictum, however, there is also no sense in not availing one self to a low-cost lunch. Well aware that the intuitively obvious solution is not always viable, couldn't we take advantage of convection air currents swirling upward through the cooling towers to capture energy via wind turbines? Recognizing air flow reduction would lower cooling efficiencies, is there a middle ground where some portion of blatantly excess losses might be recaptured?
The conversion of waste heat to usable power is easier said than done because of the "no free lunch clause" of thermodynamics. Besides, the idea of using TEGs to capture waste heat in generating station (silicon-germanium TEGs) is not new, and has not met with much economic success in the past due to the difficulty in economically producing vast amounts of of SiGe material (although there are dozens of other TE materials, most include one or more expensive/rare elements)...but I wish the professor good luck.
I agree. The amount of wasted heat energy is staggering. A lot of our power generation wastes about 50% or more of the initial thermal energy. Even capturing a fraction of the waste would be a significant increase in power available.
Just a thought.