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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