<P> The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power station's location (it may be possible to lower the temperature beyond the turbine limits during winter, causing excessive condensation in the turbine). Plants operating in hot climates may have to reduce output if their source of condenser cooling water becomes warmer; unfortunately this usually coincides with periods of high electrical demand for air conditioning . </P> <P> The condenser generally uses either circulating cooling water from a cooling tower to reject waste heat to the atmosphere, or once - through water from a river, lake or ocean . </P> <P> The heat absorbed by the circulating cooling water in the condenser tubes must also be removed to maintain the ability of the water to cool as it circulates . This is done by pumping the warm water from the condenser through either natural draft, forced draft or induced draft cooling towers (as seen in the adjacent image) that reduce the temperature of the water by evaporation, by about 11 to 17 ° C (20 to 30 ° F)--expelling waste heat to the atmosphere . The circulation flow rate of the cooling water in a 500 MW unit is about 14.2 m3 / s (500 ft3 / s or 225,000 US gal / min) at full load . </P> <P> The condenser tubes are made of brass or stainless steel to resist corrosion from either side . Nevertheless, they may become internally fouled during operation by bacteria or algae in the cooling water or by mineral scaling, all of which inhibit heat transfer and reduce thermodynamic efficiency . Many plants include an automatic cleaning system that circulates sponge rubber balls through the tubes to scrub them clean without the need to take the system off - line . </P>

Which type of coal is used in thermal power plants