The electric grid
Electricity is a secondary energy source, meaning that it is made from the conversion of other sources of energy. Traditionally, this has meant burning fossil fuels, but more and more power is now being generated by renewable energy1.
The electric grid is a system designed to provide electricity all the way from its generation to the customers that use it for their daily needs. It consists of three main sections: generation, transmission and distribution.
The generation of electricity starts in power plants. Where generation involves fossil fuels, the fuel is burned in a combustion chamber, releasing heat and producing hot exhaust gases. The heat from the combustion is used to heat water, turning it into steam. The high-pressure steam is then directed onto a turbine2, causing it to spin. The rotating turbine is connected to a generator. As the turbine spins, it drives the generator, which converts the mechanical energy3 into electrical energy. This process is similar to how natural gas and coal are used to produce electricity.
Electricity generation using renewable-energy sources is a bit different. In the case of solar energy, solar panels, made of photovoltaic cells, absorb sunlight. When sunlight strikes a photovoltaic cell, it excites electrons in the cell’s material, causing them to move and generate an electrical current. In other words, the photovoltaic effect converts sunlight directly into electricity.
Wind, which is moving air, possesses kinetic energy. Wind turbines are designed with blades that rotate when exposed to wind. The rotating blades turn a generator, which converts the mechanical energy of the rotation into electrical energy.
Once it is generated, electricity needs to be transmitted. Transmission is achieved through the use of power lines.
Electricity exiting the power plant passes through a transmission station where the electricity is “stepped-up”. This means that the voltage is increased by a transformer. This step is necessary because when travelling long distances through a conducting wire, electricity loses energy to resistance. This problem is essentially solved (at least to some level) by the use of high voltage power lines.
Finally, the electricity is distributed. Distribution begins with substations that use “step-down” transformers to bring the voltage down to levels that are safe for people to handle.
The distribution grid then connects these substations to the customers that require electricity, ranging from large industrial buildings to small homes.
A grid operator or utility dispatches generation units throughout the day on the basis of contracts, costs, and other factors. Because it is a shared network as opposed to a direct line, consumers may not be able to identify the specific power plant producing the energy they are using at any given time.
Energy on the grid moves to the nearest point it can be used, and multiple regions can exchange power depending on the capacity and needs of these regions. Steam, heat, and cooling can also be delivered through a grid, often called a district energy system. Such systems provide energy to multiple consumers, though they often have only one generation facility, and serve a more limited geographic area than electricity grids.
Different countries employ a variety of fuels for electricity production, including gas, coal, peat, oil and renewables such as wind and biomass. This is known as the electricity mix.
Globally, as of 2023, coal and gas, were the largest sources of electricity production. Of the low-carbon sources, hydropower and nuclear made the largest contribution; although wind and solar have been growing quickly.
The gap between the proportion of electricity produced by fossil fuels and that produced from renewable sources has been narrowing.
This shift is happening particularly quickly in countries like Ireland, where wind energy provided about 34% of the total electricity supply in 2023, making it the country’s largest source of renewable energy.
Countries utilize a variety of fuels to generate electricity due to factors like resource availability, cost-effectiveness, environmental concerns, and energy security needs. Some countries may have abundant fossil fuels like coal, oil, or natural gas, making them cost-effective for electricity generation. Others may rely more on renewable sources like hydro, solar, or wind power, due to environmental benefits and reduced reliance on imported fuels.
At the outbreak of the Russian invasion of Ukraine in 2022, almost half of EU gas imports were sourced from Russia. In a bid to undermine their support for Ukraine, Russia weaponised the EU’s over reliance of its energy supply by reducing and in some cases cutting off natural gas exports to Europe. Europe quickly recognized a need to end its reliance on Russian imports of fossil fuels and develop alternative ways to ensure constant energy supply. Consequently, it established the REPowerEU Plan. REPowerEU is helping the EU to save energy, diversify energy supplies and produce clean energy. It has enabled the EU to overcome its dependency on Russian fossil fuels. This led to the share of EU gas imports coming from Russia dropping from 45% in 2021 to 15% in 2023.
Footnotes
A turbine is a device that harnesses the kinetic energy of some fluid - such as water, steam, air, or combustion gases - and turns this into the rotational motion of the device itself.↩︎
Mechanical energy is the sum of kinetic energy and potential energy within a system. Kinetic energy is the energy of motion while potential energy is energy stored in an object or system of objects.↩︎