Understanding Energy Sources: Types, Uses, and Impacts

Item 12: Energy Sources

Coal

Coal is a fossil fuel (not a renewable energy source) that was formed by decomposition in the absence of oxygen from buried plant remains. Its main uses are generating electricity at power plants and as a heating fuel. Its impacts include air pollution (sulfur dioxide, acid rain, global warming from carbon dioxide) and mine tailings.

Cogeneration

A cogeneration system allows for the combined production of electricity and thermal energy from one fuel (usually natural gas), which greatly increases energy efficiency (a measure of energy savings). The combined heat and power (CHP) system is used to generate electricity in a place of use (industry, hospitals, etc.), and the heat normally lost to the atmosphere is used for various purposes (heating, hot water, etc.).

Fossil Fuels

Fossil fuels are substances formed from the transformation, in the Earth's interior, of the remains of organisms over millions of years. They are used as fuel in power stations, transport, heating, etc. Examples include coal, oil, and natural gas. They are a non-renewable resource, and their greatest impact is air pollution (smog, acid rain, climate change, etc.).

Biomass Energy

Biomass energy is contained in organic molecules that form living organisms and is present in forest and agricultural waste, animal waste, organic matter in municipal solid waste (MSW), etc. It can be exploited as fuel to generate heat or electricity or can be transformed into biofuels such as biodiesel or biogas.

Wind Power

Wind power is the mechanical energy of wind. It is used to generate movement (sailing, windmills to grind grain, or pumping water) or for conversion into electricity in mills coupled with electric generators (wind turbines, wind farms). It is a clean and renewable energy source, but it is irregular and dispersed and has a landscape impact.

Geothermal Energy

Geothermal energy is the thermal energy inside the Earth (geothermal gradient) that is used by drilling holes through which water is injected into the geothermal reservoir. Once hot, it is used for heating, or steam is generated to produce electricity. Its main disadvantage is that geothermal reservoirs are scarce (areas with volcanic activity).

Hydroelectric Power

Hydroelectric power is obtained through the use of the energy of water falling on the continents (water cycle) and is often retained by dams. Water drives the turbines at hydroelectric plants. It is a renewable energy source that emits no pollution. Impacts arise from the flooding of large areas and changes in river flow.

Nuclear Energy

Nuclear energy is currently generated in nuclear plants where nuclear fission (division of the nucleus of uranium or plutonium, etc.) releases a large amount of energy used to generate electricity. Its greatest impact is the possibility of leaks of radioactive materials, which are harmful to living organisms (mutations, cancer, etc.). Its main advantage is that it emits no carbon dioxide.

Solar Energy

Solar energy is the energy of the sun. It is used with photovoltaic systems, which directly convert light into electricity, or with solar thermal systems (with collectors to produce hot water or solar thermal power plants, which concentrate sunlight with mirrors, etc.) to heat a liquid and generate electricity. It is a clean and renewable energy source.