Step 2 : Gas Turbine: The hot gases are used to spin a gas turbine, which is connected to a generator to produce electricity.

Step 3: Exhaust: The exhaust gases from the turbine are expelled into the atmosphere.

This process is called "open cycle" because the hot exhaust gases are not reused to produce more power, unlike in a combined-cycle power plant where the exhaust gases are used to generate steam, which then drives a steam turbine for additional power generation. Open-cycle gas-fired power plants are known for their relatively high efficiency compared to other types of power plants and their ability to quickly ramp up or down to meet changing electricity demands.

Combined-cycle gas-fired power generation is a more efficient method of producing electricity compared to open-cycle gas-fired power generation. It combines two different thermodynamic cycles: the Brayton cycle (gas turbine) and the Rankine cycle (steam turbine).

Step1 : Gas Turbine: Natural gas is burned in a combustion chamber to drive a gas turbine, which generates electricity.

Step 2: Waste Heat Recovery: The hot exhaust gases from the gas turbine are directed to a heat recovery steam generator (HRSG).

Step 3: Steam Turbine: The HRSG produces steam using the heat from the exhaust gases. This steam is then used to drive a steam turbine, which generates additional electricity.

Efficiency: Because the waste heat from the gas turbine is used to produce steam and generate more electricity, combined-cycle power plants are much more efficient than open-cycle plants.

Environmental Impact: Combined-cycle plants produce fewer emissions per unit of electricity generated compared to traditional fossil fuel power plants, making them a more environmentally friendly option.

Combined-cycle gas-fired power plants are a popular choice for large-scale electricity generation due to their high efficiency and lower environmental impact compared to other fossil fuel-based power generation methods.

Coal-fired power generation is a process that involves burning coal to generate electricity. While coal has historically been a major source of energy for electricity generation, its use has been declining in many parts of the world due to concerns about air pollution and greenhouse gas emissions.

Emissions: Coal combustion produces emissions such as carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter, which can have environmental and health impacts.

Efforts to reduce the environmental impact of coal-fired power generation include the use of more efficient technologies, such as supercritical and ultra-supercritical boilers. The implementation of emissions control technologies, such as scrubbers and selective catalytic reduction (SCR) systems. However, many countries are also phasing out coal-fired power plants in favor of cleaner energy sources, such as natural gas, renewable energy, and nuclear power.