Once-through Cooling Systems
Thermoelectric power plants often make use of once-through cooling (OTC), a system whereby the water from nearby waterbodies is circulated through pipes to absorb heat from the steam in the condensers. The emission of this heated water back into the waterbody can have significant ecological impacts. For example EFDC+ has been used to determine possible thermal impacts on the beluga whale, riverine snails, macroalagae, and other wildlife.
An additional challenge for operators and regulators is the issue of forced evaporation. The higher temperature of the water body due to the thermal emission leads to high rates of evaporation. EE has built in tools for calculating the effect of this phenomenon.
The EE Modeling System has been used extensively to simulate the impacts of thermal diffusion from power plants. The animation below shows output from an EFDC model of a thermal plume emitted from the OTC system of a nuclear power station.
The EFDC+ model has also been used to simulate real time OTC systems to support decision makers in the plant operations. Based on meterological forecasts the operators can estimate allowable OTC emissions that will remain within compliance limits set by regulators. The image below shows output from a EFDC real-time model for temperature at a compliance buoy for a given operational scenario at power plant.
Pumped Storage Facilities
In pumped-storage hydroelectric power plants the pumping of water from a lower reservoir to an upper impoundment, and the return of that water during power generation, can strongly affect the water quality of the reservoirs. In particular, plant operation can alter their thermal structure, deep water mixing, and water circulation characteristics.
Using the Sigma Zed model allows engineers to better determine the impacts of the pumping regime being used in different seasons, including habitat analysis for aquatic plants and animals.
