Energy sources

Fossil fuels are a non-renewable energy source, formed from the remains of lived organisms millions of years ago.
Fossil fuels include coal, oil, and natural gas.
Exploitation of these fuels burns carbon and releases large amounts of carbon dioxide (CO2) into the atmosphere, a greenhouse gas responsible for global warming.

Renewable energy, also called clean or green energy, replenishes naturally in a relatively short time.
Forms include hydro, wind, solar, geothermal, and biomass energy.
Hydroelectric energy is obtained from the potential energy of stored water in dams, which is transformed into mechanical and subsequently electrical energy.
Wind energy exploits air flow using wind turbines to generate electricity.
Solar power utilises energy from the sun’s light, converting it into electricity.
Geothermal energy harnesses heat from the earth’s core to generate power.
Energy from biomass comes from organic material - such as plant-based waste - undergoing combustion.

Nuclear energy originates from the nucleus of an atom. The process of nuclear fission can release this energy as heat, which can create steam, powering turbines and generating electricity.
While nuclear power does not produce CO2, it produces hazardous radioactive waste which is difficult to manage and dispose of safely.
Nuclear fusion, a process yet to be effectively harnessed for energy production, promises cleaner and virtually limitless power but presents enormous technical challenges.

The Law of Conservation of Energy means no energy is lost, rather it transforms from one form to another.
The efficiency of an energy system is the proportion of the total energy input that does useful work.
Energy loss usually occurs due to heat loss through friction or air resistance.
Energy systems are designed to maximise efficiency and minimise loss, hence improving energy sustainability and reducing environmental impact.