The Changing Face of Power Grids

To slow down climate change, most countries want to say goodbye to fossil fuels. At the same time, however, the demand for electrical energy is increasing. What does this mean for our grids?


Ever since industrialization began, CO2 emissions from burning fossil fuels have been steadily on the rise. The growing concentration of carbon dioxide in the atmosphere is considered the main cause of climate change, and experts agree that replacing fossil fuels with energy sources that are free from CO2 emissions is an essential step toward slowing this trend.

Worldwide, around 80 percent of our energy needs are still met by fossil fuels—which means that only around 20 percent are being met by their CO2-neutral counterparts such as hydropower, nuclear power, natural fuels (biomass, wood, waste), and other renewable sources such as wind power and solar power. In an attempt to slow the acceleration of climate chan­ge, many countries have re­solved to replace fossil fuels with renewable sources of energy.

Our total energy needs

Worldwide, around 80 percent of our total energy needs are still met by fossil fuels—which means that only 20 percent are met by CO2-neutral sources. But this picture is set to change.

2 % Other renewable energy sources
2 % Hydropower
5 % Nuclear power
10 % Biofuel
22 % Natural gas
27% Coal
32% Crude oil

Down With Emissions

The most straightforward way of shifting to alternative forms of energy is to start harnessing the power of the sun and wind, both of which are in plentiful supply and surpass the global demand for primary energy—which is currently around 170,000 terawatt-hours (TWh) annually—sev­eral times over. At least theoretically, therefore, a world of emis­sion-free energy would be more than pie-in-the-sky thinking.

Con­versely, we need to consider whether this solution would result in a future where huge quantities of primary energy were being transported through grids in the form of electrical energy—some­thing that would significantly add to the 27,000 TWh that our grids carry today. This sce­nario therefore leaves us with some big questions to answer: How much energy do we actually need to sub­stitute? How is demand for power likely to develop in the future? And what kind of im­pact would grids feel if they were re­quired to transport sig­nificantly more power?

Useful Energy is the Key

The good news is that the bulk of primary energy is lost during power generation and never actually reaches grids. This is because both conventio­nal and nuclear power plants are essentially nothing more than thermal machines that convert heat into mechanical energy, which itself is then converted into electrical power. They can only perform this process by incurring huge losses—in most cases, these plants operate at efficiency levels of only around 40 percent.

The only kinds of plants that deliver much better results are gas-fired ones. As a result, grids actually transport a comparatively low amount of primary energy for use. This is known as useful energy. The efficiency at which solar and wind power plants operate is less important, as generating power using these resources does not incur any primary energy costs. Only the investment and ongoing costs over the lifetime of these plants need to be considered in deciding whether they present an economically and environmentally sound choice.

Goodbye to Coal and Oil

Around three quarters of coal pro­duction goes into providing a primary energy source for generating power. In a scenario where coal were to be substituted with solar and wind power plants, only the proportion of useful energy would need to be replaced—that is, the electricity generated from heat.

The same effect can be observed in the use of mineral oil in combustion engines, which are on a much smaller scale compared to power plants and operate at efficiency levels below 30 percent. In this case too, only the proportion of useful energy (30 percent) would need to be replaced with renewable energy sources in a scenario where electric vehicles were used instead. Given that mineral oil accounts for 40 percent of primary energy consumption for transport, a total of only about nine percent of electrical energy for electrically powered vehicles would be needed. This amount of energy would also need to be transported through electricity grids in the event of a complete switchover to electric drive formats.

By 2040, global energy demand will be one and a half times what it is today.

Thermal power plants and combustion engines represent the largest consumers of coal and mineral oil, but others include heating systems (which use both) and industrial applications such as steel and cement production (which relies on coal). However, there are also substitution options available for the technology used in these cases. In heating systems, for example, requirements for fossil fuels as a source of primary energy could be reduced mal power plants, since gas turbines can be operated at significantly high­er temperatures, with steam turbines running downstream of them. Another advantage of this technology is that gas-fired power plants offer the most flexible management methods out of all the options available.

 

Growing Demand

Around 17 percent of the current global demand for energy is met in the form of electricity flowing through our grids. Approximately 37 percent of this is already free from emissions. With a view to the future, grid planners will need to account for not only a range of scenarios in which conventional energy sources would be replaced by other sources, but also those in which demand would grow.

Quite simply, the world’s appetite for energy is fierce and many emerging and developing countries are furiously trying to play catch-up. Around 650 million people worldwide still have no access to electricity, so experts believe that by 2040 energy demand will be one and a half times what it is today. Based on this assumption, the International Energy Agency (IEA) has developed two possible future scenarios.

Electricity gen­eration from oil, meanwhile, would virtually disappear and there would be an 80 percent reduction in gen­eration from coal.

All in all, current planning figures envisage the emission-free proportion of electrical energy gen­eration growing to between 52 and 79 percent by 2040, with electricity generation rising by one and a half times in total. Measured against today’s installed base, this would result in energy from nuclear power growing by 0 to 33 percent, from hydropower by 50 to 75 percent, from wind by 400 to 700 percent, from solar plants by 400 to 700 percent, and from other renewable sources by 100 to 200 percent.

Electricity gen­eration from oil, meanwhile, would virtually disappear and there would be an 80 percent reduction in gen­eration from coal. As things stand, the amount of energy generated from gas is set to remain stable or grow by up to 50 percent, depending on how things develop. Gas is the most environmentally sound fossil-based energy source, and the plants that are fired by it also have the potential to use gas produced using regenerative methods, allowing them to provide a storage or buffer function


Two electrical energy scenarios

Around 17 percent of the current global demand for energy is met in the form of electricity flowing through our grids. Approximately 37 percent of this is already free from emissions. With a view to the future, grid planners will need to account for scenarios in which conventional energy sources would be replaced and demand would grow. Experts believe that energy demand is set to grow by as much as 50 percent by 2040. For this reason, the International Energy Agency (IEA) has developed two possible future scenarios.

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