Different fuel types have vastly different effects on greenhouse gas emissions in the electricity sector. Here is a breakdown.
Coal
Produces the highest amount of CO2 emissions per unit of electricity generated due to its carbon-rich composition. Coal-fired power plants are a major source of global greenhouse gas emissions, releasing large quantities of carbon dioxide and other pollutants like sulfur dioxide and mercury.
Natural Gas
Emits about 50-60% less CO2 than coal when burned for electricity, making it a cleaner, though not emission-free, alternative. Methane leaks during extraction and transportation can undermine its lower carbon footprint, as methane is a potent greenhouse gas.
Oil
Less commonly used for electricity generation but highly carbon-intensive when employed. Burning oil for power generates significant amounts of CO2 and other pollutants, including nitrogen oxides and particulates.
Nuclear
Produces minimal direct CO2 emissions during electricity generation. The emissions are primarily associated with plant construction, uranium mining, processing, and waste management, but on a lifecycle basis, it's considered low-carbon.
Hydroelectric
Generally produces very low direct greenhouse gas emissions. However, reservoirs can emit methane and CO2 from decomposing organic material, particularly in tropical regions, though these emissions are significantly lower than fossil fuel sources.
Wind
Generates electricity without direct emissions of greenhouse gases. The main emissions come from the manufacturing, transportation, and installation of turbines, but these are relatively low over the turbine's lifecycle.
Solar
Has minimal direct emissions during operation. The majority of emissions result from the manufacturing of solar panels, including the extraction of raw materials and the energy used in production processes.
Biomass
Considered carbon-neutral under certain conditions, as the CO2 released during combustion is offset by the carbon absorbed by the plant material during its growth. However, emissions can vary based on the type of biomass, its source, and how it is harvested and processed.
Geothermal
Low emissions compared to fossil fuels, with most emissions arising from plant construction and the release of non-CO2 gases like sulfur dioxide. The direct CO2 emissions from geothermal plants are relatively minor.