Electricity is the motion of electrical charge or power. It is both a fundamental part of nature and one of the most extensively used types of energy. The electricity that we consume is a secondary energy form because it is generated by converting primary energy sources, such as nuclear energy, coal, solar energy, natural gas, wind energy, and tidal energy, into electrical energy (through different methods). Electricity can also be called an energy carrier, as it can be transformed into other types of energy, such as heat or mechanical energy. Primary energy sources include both renewable energy and non-renewable energy sources.
Let’s go through the six best sources of electricity.
Natural gas (fossil gas) is a naturally existing gaseous hydrocarbon mixture primarily composed of methane and smaller quantities of other types of higher alkanes. It is a fossil fuel and non-renewable energy source that is generated when many layers of organic matter (predominantly marine organisms) chemically break down under anaerobic conditions and are exposed to intense pressure and heat buried in the Earth over millions of years. The energy that the decomposed creatures originally gained from the Sun through photosynthesis is accumulated as chemical energy within the methane and other hydrocarbon molecules. It can be used to produce electricity in numerous ways. The simplest natural gas-powered electricity production unit is composed of a steam production unit, where these fuels are burned in a boiler to vaporise water and generate steam that then pushes a turbine to create electricity.
Nuclear power is the application of nuclear reactions to generate electricity. It can be obtained from nuclear decay, nuclear fusion, and nuclear fission reactions. Currently, the bulk of electricity from nuclear power is generated by the nuclear fission of plutonium and uranium in nuclear power stations. The majority of nuclear power plants employ thermal reactors with enriched uranium. The fuel is separated when the relative amount of neutron-absorbing atoms become so huge that chain reactions can no longer be activated, usually for three years. Then, it is cooled for numerous years in on-site spent nuclear fuel pools before being shifted to long-term storage. A nuclear fission plant is typically composed of a nuclear fission reactor in which the nuclear reactions generate heat energy. The cooling system removes heat from the interior of the nuclear reactor. The steam turbine transforms the heat energy into mechanical energy. The electric generator converts mechanical energy into electricity (electric energy).
Coal is a combustible sedimentary rock, occurring as rock strata known as coal seams. It is mostly made of carbon and minor quantities of other elements (oxygen, hydrogen, nitrogen, and sulphur). It is formed when dead plant bodies decompose into peat and are transformed into coal by the pressure and heat of deep burial for over several million years. A huge amount of chemical energy is stored as a result of such a long process. Coal power plants are thermal power stations which burn coal compounds to produce electricity globally. There are about 8,500 coal-based power plants totalling around 2,000 gigawatts of production capacity. The hundred biggest coal power plants range from 3,000MW to 6,700MW. They produce about one-third of total global electricity.
Hydropower (hydroelectric power) is one of the biggest and oldest renewable energy sources, which uses the natural motion of moving water waves to produce electricity. Hydroelectric power is the use of fast-moving or falling water to generate electricity or to propel machines. This is attained by transforming the gravitational potential energy or kinetic energy of water sources to generate power. Hydroelectric power is a sustainable energy generation method. Most hydropower plants generate power by utilising the elevation variation created by dams or diversion structures. Such a power resource can be analysed by its available power range. Power is a direct function of the volumetric flow rate and hydraulic head. Generally, the head is equal to the energy per unit mass (or in unit weight) of water. In fact, the static head increases when the height difference (through which water descends down) increases. Individual water units can do work equivalent to the weight times the head value.
Solar radiation is electromagnetic radiation that is emanated by the Sun. Most of the places on the Earth receive some amount of sunlight in a year. As per geographical features, the amount of radiation that enters any one location on the Earth’s surface often varies. The total sunlight that hits the surface of the Earth in one and a half an hour is enough for the entire global energy consumption for an entire year. Solar power is the transformation of light energy (solar light) into electricity, either directly utilising photovoltaics or indirectly employing concentrated solar power or combinations. Photovoltaic cells transform light into electric current by applying the photovoltaic effect. A concentrated solar system uses mirrors or lenses and solar tracking tools to focus a huge area of solar radiation to a hot pot, typically to drive steam turbines.
Initially, photovoltaics were exclusively used as an electricity source for small and medium-range applications, from calculators or watches powered by the mono solar cell to moving houses powered by off-grid rooftop PV systems. Fully commercial concentrated solar power stations were first constructed in the 1980s. Then onwards, as the production cost of solar energy decreased, the popularity of grid-attached solar PV systems ascended exponentially. Millions of such systems are being installed across the world. Solar PV is on its way to becoming one of the most viable and reliable low-carbon energy technologies. In fact, since 2020, it has provided the most affordable source of electricity.
Wind power is the use of wind turbines to produce electricity. The wind is a popular, renewable, sustainable source of energy with a much smaller effect on the environment than the burning of hydrocarbon fuels. Wind energy is the kinetic energy of air in motion, also known as wind. Throughout history, wind energy has been utilised for propelling windmills, windpumps, and sails, but currently, it is predominantly used to produce electricity. Wind power plants consist of numerous wind turbines, which are attached to the electric power networks. In wind farms, individual wind turbines are interconnected with a relatively medium voltage (typically 34.5 kV) power storing system and communication network. Usually, a length of 7D (seven times the wind turbine’s root diameter) is between each wind turbine in a fully constructed wind farm. At substations, the medium-voltage electric current is raised in voltage using a transformer for synching to the high-voltage power transmission systems.
Since the dawn of human civilisation, people have utilised biomass energy from many sources like wood and other organic matter. As time passed, we gradually shifted using this resource from cooking or heat applications to electricity and other energy applications. Currently, biomass is extensively used to power electric generators and other powerful machinery. The most common examples of biomass are wood, energy crops, agricultural remnants, and industrial and household organic waste. As biomass can be directly utilised as a fuel, it can also be called biofuel. Biomass is composed of energy first absorbed from sunlight; plants absorb the sunlight through photosynthesis and convert water and carbon dioxide into carbohydrates (nutrients).
The energy from living things can be converted into usable energy form through both direct and indirect methods. Biomass can be converted into electrical energy (direct), burned to produce heat (direct), or processed into another type of fuel (indirect). Most electricity produced from biomass is created by direct combustion. Biofuel is burned in a boiling machine (boiler) to generate high-pressure steam. The resultant steam flows over a network of turbine blades, forcing them to rotate. The rotational motion of the turbine powers a generator, creating electricity. Biomass could also act as an alternative for a percentage of coal used in power station furnaces in a method called co-firing (using two different kinds of substances simultaneously).
As science and technology evolve, electricity will largely replace diesel and petrol as fuel for terrestrial vehicles. It will also dominate over the oil and natural gas we burn to cook and heat and power most industries. Ultimately, electricity will grow in prominence even more as a carbon-free energy substitute.