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.