Electricity is essential to modern life, but nearly a billion people live without access to it. Challenges such as climate change, pollution and environmental degradation demand that we change the way we generate electricity.
In the last century, the main energy sources for electricity generation have been fossil fuels, hydroelectric power and, since the 1950s, nuclear power. Despite the strong growth of renewable energy in recent decades, fossil fuels remain dominant worldwide. Their use for electricity generation continues to grow in both absolute and relative terms: in 2017, fossil fuels generated 64.5% of the world's electricity, up from 61.9% in 1990.
Access to reliable electricity is vital to human well-being. One in seven people in the world currently has no access to electricity. The demand for electricity will therefore continue to rise. At the same time, greenhouse gas emissions must fall drastically if we are to curb climate change, and we must switch to cleaner energy sources to reduce air pollution. This will likely require a major build-out of all low-carbon energy sources, of which nuclear power is a large part.
To achieve a sustainable world, all economic sectors must be decarbonized, including transport, heating and industry. Electricity offers the opportunity to use low-carbon energy sources and widespread electrification is therefore seen as a key tool for decarbonising sectors traditionally fueled by fossil fuels. As end-uses of electricity increase and the benefits of electricity are made available to all, demand will increase significantly.
coal, gas and oil
Fossil fuel power plants burn coal or oil to produce heat, which in turn is used to generate steam to drive turbines that produce electricity. In gas-fired power plants, hot gases drive a turbine to produce electricity, while a combined cycle (CCPP) power plant also uses a steam generator to increase the amount of electricity produced. In 2017, fossil fuels generated 64.5% of the world's electricity.
These power plants generate electricity reliably over a long period of time and are usually inexpensive to build. However, the burning of carbon-based fuels produces large amounts of carbon dioxide, which drives climate change. These plants also produce other pollutants such as sulfur and nitrogen oxides that cause acid rain.
Cottam power station in the UK, using coal and gas to generate electricity (Image: EDF Energy)
Burning fossil fuels to generate electricity causes a significant number of deaths due to air pollution. For example, it is estimated that 670,000 people die prematurely every year in China alone as a result of the use of coal.
Fossil fuel power plants require large amounts of coal, oil or gas. In many cases, these fuels have to be transported over long distances, creating potential supply problems. Historically, fuel prices have been volatile and can rise sharply during times of scarcity or geopolitical instability, leading to unstable generation costs and higher consumer prices.
Most large hydroelectric power plants generate electricity by storing water in large reservoirs behind the dams. The water from the reservoirs flows through turbines to generate electricity. Hydroelectric power plants can generate large amounts of electricity with low carbon emissions, but the number of suitable sites for new large-scale dams is limited. Hydroelectric power can also be generated by run-of-river power plants, but most rivers suitable for this have now been developed.
The Three Gorges Dam in China is the world's largest dam and the world's largest power plant (Image:the great toll,CC BY-SA 2.0)
In 2017, hydropower accounted for 16% of global electricity generation.
Flooding of reservoirs behind dams and reduced flow in the river system downstream of the dam can also have serious impacts on the environment and local people. For example, around 1.3 million people were displaced during the construction of the world's largest hydroelectric power station, the Three Gorges Dam in China.
Measured by the number of accidental deaths, hydropower is the deadliest source of energy. The deadliest accident was the 1975 collapse of the Banqiao Dam in China's Henan province, which official estimates claimed 171,000 direct and indirect deaths.
Nuclear power plants use the heat produced by the fission of atoms to generate steam to drive a turbine. No greenhouse gases are produced during nuclear fission and only very small amounts during the nuclear life cycle. Nuclear power is an environmentally friendly way of generating electricity and does not contribute to air pollution. In 2018, nuclear power generated 10.5% of the world's electricity.
The Paluel nuclear power plant in northern France, one of the largest nuclear power plants in the world (Image: Areva)
Nuclear power plants, such as those that run on fossil fuels, are extremely reliable and can run for many months without interruption, providing large amounts of clean electricity regardless of the time of day, weather or season. Most nuclear power plants can run for at least 60 years, which helps make nuclear power the cheapest compared to other power generators.
Nuclear fuel can be used in a reactor for several years thanks to the immense amount of energy that uranium contains. The energy of a kilogram of uranium is roughly equivalent to that of a ton of coal.
This results in correspondingly little waste. On average, a reactor that supplies one person's electricity needs for a year generates about 500 grams of waste: it would fit in a soda can. Only 5 grams of this amount is used as nuclear fuel, which is equivalent to a sheet of paper. Various management strategies are available for spent fuel, e.g. B. direct disposal or recycling in reactors to generate more low-carbon electricity.
wind and sun
Renewable energies such as wind, solar and small hydro generate electricity with low greenhouse gas emissions throughout their life cycle. In 2017, wind and solar generated 4.4% and 1.3% of the world's electricity, respectively. Due to their inherent dependence on the weather, they do not produce electricity in a predictable or consistent manner. Electricity production from wind turbines varies with wind speed, and when the wind is too weak or too strong, no electricity is produced. The performance of solar panels depends on the intensity of sunlight, which depends on various factors such as: B. the time of day and the amount of clouds (as well as the amount of dust on the modules).
Another problem is that there may not be enough space or public facilities to accommodate the large number of turbines or panels needed to generate enough electricity. This is because the energy from wind or sun is dispersed, meaning very large areas of land are required to generate a significant amount of electricity.
Since electricity cannot be easily stored, renewable energy must be supported by other forms of electricity generation. The largest batteries cannot run for days, let alone the weeks it would take to back up renewable sources to ensure 24/7 power. To ensure a constant power supply, gas-fired power plants are increasingly taking on backup services for renewable electricity. Natural gas plants emit large amounts of carbon dioxide during operation, and significant amounts of methane are often released during gas production and transportation, both of which contribute to climate change.
A biomass power plant works in a similar way to gas and coal power plants. Instead of burning gas or coal, the plant runs on various types of biomass (such as specially grown trees, woodchips, household waste, or "biogas"). In 2017, biomass generated 2.3% of the world's electricity.
The Drax power station in the UK partially replaced coal with imported biomass as fuel for power generation (Image:Andre Whale,CC BY-SA 2.0)
Biomass production can be energy intensive, both in terms of producing the biomass itself and in terms of transportation. Because of this, the energy required can be greater than the energy value of the final fuel, and greenhouse gas emissions can be as high or even higher than equivalent fossil fuels. In addition, it can take more than 100 years for the emitted carbon dioxide to be absorbed, leading to a short-term increase in emissions.
Other environmental impacts related to land use and environmental sustainability can be significant. Like coal, biomass use can contribute to air pollution and therefore negatively impact the health of local biomass crop populations.
What will drive our electric future?
Electricity becomes more important. If we are to combat climate change and reduce air pollution, we must increase the use of all low-carbon energy sources, of which nuclear power is a large part.
To meet the growing need for sustainable energy, the World Nuclear Association launched the Harmony program, which aims to have nuclear power provide at least 25% of electricity by 2050. This would mean nuclear power generation would have to triple to world levels then. In order to drastically reduce the share of fossil fuels, nuclear power and renewable energy must work together to ensure a reliable, affordable and clean energy supply for the future.
Die World Nuclear Associationsilent giant white paperprovides more information on the need for nuclear energy in a clean energy system.