Generation Efficiency of Thermal Power

Large-scale, continuously operational commercial electric utility power plants are typical in their construction. Almost all electric power plants generate alternating current electricity at frequencies of 50 Hz or 60 Hz using three-phase electrical generators. Large organizations, especially those where steam is produced for other purposes, may have their own power plants to provide heating or electricity to their facilities. The majority of ships were propelled during the majority of the 20th century by steam-driven power systems.
Thermal power plants can be built using a variety of energy sources, including fossil fuels, geothermal, nuclear, solar, biofuels, and waste incineration. In addition to producing electricity, some thermal power plants are also built to produce heat for the desalination of water, district heating, or industrial applications.
The saleable energy produced as a percentage of the heating value of the fuel consumed is the definition of a traditional thermal power plant’s energy efficiency. The energy conversion efficiency for a single-cycle gas turbine range from 20 to 35%. Modern fossil fuel plants operate at 46% efficiency, while conventional coal-based power plants function at 35 to 38% efficiency at 170 bar and 570 °C. Systems with a combined cycle can achieve higher values. Their efficiency is constrained and restricted by the laws of thermodynamics, just as that of all heat engines.
A pressurized water reactor (PWR) uses a certain kind of huge heat exchanger to thermally connect the primary (reactor plant) and secondary (steam plant) systems, which produce steam. This device is referred to as a “steam generator” in the nuclear power industry. In a boiling water reactor, water boils inside the reactor core without the usage of a separate steam generator.
Heat recovery steam generators, which use heat from industrial processes, most frequently hot exhaust from a gas turbine, are also capable of creating steam in some industrial contexts. For the steam turbine that powers the electrical generator, the steam-generating boiler must produce steam at the high purity, pressure, and temperature required.
Thermal power plants must release any energy that is not used to generate electricity into the atmosphere as heat. This waste heat can be condensed and discarded in cooling towers or using cooling water. Cogeneration refers to the process of using waste heat for district heating instead. Desalination facilities are a significant class of thermal power plants; these plants are often found in arid regions with abundant natural gas, and they produce both electricity and fresh water as significant byproducts. Different efficiency restrictions apply to other kinds of power plants. The majority of hydropower plants in the United States convert water’s kinetic energy into electricity with an efficiency of over 90%, whereas a wind turbine’s efficiency is constrained by Betz’s rule to roughly 59.3% and real wind turbine performance is lower.
For contemporary utility-connected generators, the generating voltage ranges from 11 kV in smaller units to 30 kV in larger units. Due to their higher current than the cables used in smaller machines, the high-voltage leads for generators are often made of wide aluminum channels. They are supported on adequate insulators and housed in well-grounded aluminum bus ducts. In order to connect to a high-voltage electrical substation (often in the range of 115 kV to 765 kV) for onward transmission by the local power grid, the high-voltage leads from the generator are linked to step-up transformers. Additionally, the generator uses water cooling. An insulating barrier, such as Teflon, is utilized to connect the water line and the high-voltage windings of the generator because the generator coils are at a potential of around 22 kV. It is utilized low-conductivity demineralized water.
While air collected via filters at the input can be used to cool small generators, bigger ones often require separate cooling equipment. Because hydrogen has the highest known heat transfer coefficient of any gas and because of its low viscosity, which lowers windage losses, it is utilized for cooling in an oil-sealed casing.n