Electronic International Standard Serial Number (EISSN)
Thermoelectric plants consume large amounts of water for electricity generation, mainly for coolingpurposes. The performance and cooling capacity of power plants is thus strongly dependent on risingambient temperatures. This study investigates the effect of rising ambient temperatures on power-plantperformance and water use. A natural gas combined-cycle and a coal power plant, using both recircu-lating and once-through cooling systems, have been analyzed under increasing cooling water temper-ature and increasing ambient air temperature. Higher ambient temperatures lead to higher pressure atthe steam turbine outlet, decreasing power-plant performance. The efficiency of the power plants isfound to be more sensitive to ambient temperature variations when a recirculating cooling system isused, as opposed to once-through cooling. For example, a 10 C temperature increase leads to an effi-ciency decrease in coal plants of 0.5e0.7 percentage points, when they are equipped with recirculatingsystems, versus a 0.3e0.4 percentage-point decrease, when they are equipped with once-through sys-tems. The cooling-water massflow is also found to be more sensitive to temperature increases in plantswith recirculating cooling than in plants with once-through cooling. When comparing coal to natural gasplants, it is seen that the cooling water quantity of coal-fired plants is more sensitive to temperaturechanges. On the other hand, the efficiency of natural gas plants is more sensitive to temperature changesoverall. This is related to higher losses in gas turbine systems caused by increased ambient temperaturesand to the fact that the gas turbine system delivers approximately two-thirds of the total power output inthe natural gas plants.
climate change; energy and water nexus; energy security; power plants; water consumption