Municipal Energy Transition“Crowd concepts for battery storage systems are not just an option. They are a must!”

No ener­gy tran­si­tion with­out short-term stor­age: Pro­fes­sor Bruno Burg­er from Europe’s largest solar research insti­tute explains why experts agree on this point.

Professor Burger, the energy turnaround is now to move ahead rapidly. In the German government’s “Easter Package,” it was decided to expand solar and wind energy to 360 GW by 2030. Can the power grids even absorb this amount without additional storage capacities?

No. We need more trans­port capac­i­ty from north to south and, above all, we need lots of bat­tery stor­age by 2030.

Why is battery storage so important for the future of grids?

Let’s take a look at the elec­tric­i­ty con­sump­tion of an aver­age week in 2030. It becomes clear that we will need more stor­age than before because dur­ing the day, gen­er­a­tion is greater than load due to solar feed-in. This means that we need to store elec­tric­i­ty at mid­day, which we then con­sume at din­ner time; and at night, we can store wind pow­er that is then avail­able to us at break­fast. So the stor­age has two cycles a day. This is the per­fect appli­ca­tion for a bat­tery.

Are there no alternatives to battery storage such as pumped storage power plants or electrolyzers?

Since we will main­ly need short-term stor­age up to 2030, pumped stor­age would be an alter­na­tive. How­ev­er, we do not have suf­fi­cient resources for this, at least not in Ger­many and there are only a few pos­si­ble sites for new con­struc­tion. And even if we expand them, that would still be far from suf­fi­cient for the ener­gy tran­si­tion.

Hydro­gen will not play a role until 2030. Only then will we have sig­nif­i­cant sur­plus­es to start produc­ing it. How­ev­er, we should not con­vert the green hydro­gen back into elec­tric­i­ty, which would gen­er­ate loss­es again, but rather use it direct­­ly in indus­tri­al process­es to make its use as effi­cient as pos­si­ble. In this respect, elec­trolyz­ers will only play a role in the ener­gy indus­try in the medi­um term.

„By 2030, we will need around 250 GWh of bat­tery stor­age. As of today, we have 4 GWh.“

What volumes are we talking about? How great is the need for storage in the grids?

For our fore­casts, we sim­u­lat­ed the ener­gy tran­si­tion up to 2045 on an hourly basis and used this to cal­cu­late the demand for bat­tery stor­age. By 2030, we will need around 250 GWh of bat­tery stor­age. As of today, we only have around 4 GWh so these are huge dimen­sions that are com­ing our way.

Which network levels are mainly affected by this expansion?

This will take place at all grid levels—from grid boost­ers with up to 250 MW to small PV stor­age units in pri­vate homes with 5 kW. How­ev­er, grid boost­ers have a spe­cial posi­tion. They belong to the trans­mis­sion sys­tem oper­a­tors and are there­fore not allow­­ed to par­tic­i­pate in the elec­tric­i­ty mar­ket accord­ing to cur­rent reg­u­la­tions. This means that they are only used in the event of faults or grid bot­tle­necks to avoid redis­patch mea­sures. It’s real­ly a pity that such huge invest­ments are only allowed to per­form a few tasks and are not per­ma­nent­ly in use. It would make more sense to change the reg­u­la­to­ry frame­work and open up these capac­i­ties to the elec­tric­i­ty mar­ket.

There are already many approach­es for renew­able pow­er plants. In this way, oper­a­tors can cir­cum­vent restric­tions applic­a­ble to grid con­nec­tions. Bat­tery stor­age can be used to install more pow­er and bet­ter adapt the gen­er­a­tion curve to the avail­able grid capac­i­ties. Cou­pled solar and wind parks with bat­tery stor­age could then offer more or less reli­able gen­er­a­tion and mar­ket it accord­ing­ly.

“A sig­nif­i­cant por­tion of renew­ables are being fed into low volt­age.“

A large part of the energy transition will take place in the distribution networks. What does it look like there?

Yes, the dis­tri­b­u­tion grids are par­tic­u­lar­ly affect­ed. By 2030, for exam­ple, the Ger­man gov­ern­ment wants to expand onshore wind pow­er to 115 GW and solar to 215 GW. A great deal of this will be local­ly dis­persed. Espe­cial­ly in the south, there will be no large wind farms, but rather indi­vid­ual sys­tems that will then feed into the dis­tri­b­u­tion grid. And solar is also large­ly found on roofs. This means that a sig­nif­i­cant pro­por­tion of renew­ables will be fed into the low-volt­age grid.

What role do battery storage systems play at this level?

Pri­vate house­holds can use bat­tery stor­age to save their solar pow­er gen­er­a­tion through­out the day for the high-con­sump­tion evening hours. Instead of feed­ing the elec­tric­i­ty into the grid for a low feed-in tar­iff (cur­rent­ly this is 8.2 cents/kWh for new instal­la­tions), they can con­sume it them­selves and cur­rent­ly save them­selves 30 to 40 cents per kWh in pur­chas­ing costs.


On the inter­ac­tive web­site devel­oped by Prof. Bruno Burg­er, users can freely con­fig­ure all graph­ics on elec­tric­i­ty pro­duc­tion, and elec­tric­i­ty mar­ket prices in all coun­tries of Europe. The site is fed by a vari­ety of neu­tral and always up-to-date sources and wants to con­tribute to more trans­paren­cy and an objec­ti­fi­ca­tion of the dis­cus­sion about the ener­gy tran­si­tion.

What about the batteries of electric cars? There is always talk here of crowd concepts. Do you think that’s a realistic option?

This is not just an option. It is a must! Because if we have fluc­tu­at­ing gen­er­a­tion, we should adjust the loads to the gen­er­a­tion if pos­si­ble. It is always cheap­er to con­sume elec­tric­i­ty direct­ly than to store it and con­sume it with a time lag. So, as a first step, it is impor­tant that we have control­lable loads that increase elec­tric­i­ty con­sump­tion when there is a lot of renew­able ener­gy avail­able. That means, for exam­ple, that you go to work in the morn­ing and expect your bat­tery to be full by the evening. What hap­pens in the meantime—whether charg­ing stops, what pow­er is used for charging—doesn’t mat­ter. This is all left to a con­trol sys­tem.

Con­cepts to inte­grate bat­ter­ies bidi­rec­tion­al­ly and then to com­pen­sate the cus­tomer for this ser­vice are more dif­fi­cult. This rais­es the ques­tion of who is respon­si­ble for con­trol and remu­ner­a­tion? Do the dis­tri­b­u­tion net­work oper­a­tors have access to all charg­ing sta­tions and wall­box­es, or should the man­u­fac­tur­ers of the elec­tric cars instead do this?

“High­er prices would be an incen­tive to bet­ter match con­sump­tion to gen­er­a­tion. So there’s already a strong case for invest­ing in ener­gy stor­age across the board.”

Will car manufacturers thus become participants in the electricity market?

Yes, because the man­u­fac­tur­ers already have com­mu­ni­ca­tion inter­faces to their vehi­cles and cus­tomers. They are in con­stant con­tact with cars, for exam­ple, to upload soft­ware updates and the like. These inter­faces could also be used to con­trol the charg­ing of the bat­ter­ies. The man­u­fac­tur­er, Volk­swa­gen for exam­ple, could pool this func­tion and thus con­trol the charg­ing of the entire fleet depend­ing on mar­ket elec­tric­i­ty prices, so that renew­able ener­gies are used opti­mal­ly. It could also charge the elec­tric­i­ty costs direct­ly to the cus­tomer, which would be a sim­pler solu­tion than con­trol­ling it via the wall­box.

Who are the battery storage operators and how are they financed?

The grid boost­ers are financed by a levy on the grid fees. Oth­er­wise, any­one will build stor­age facil­i­ties for whom it pays off. The pri­vate cit­i­zen, because he pro­duces solar pow­er for 6 cents per kWh and saves 40 cents; and it is also inter­est­ing for com­pa­nies. If they have high elec­tric­i­ty prices and store their own gen­er­a­tion in such a way that it fits bet­ter with con­sump­tion, then that is already an argu­ment. If a com­pa­ny doesn’t have its own gen­er­a­tion, it can use stor­age to low­er peak prices or pur­chased-pow­er lev­els. This is also of inter­est for munic­i­pal­i­ties and pub­lic util­i­ties. There are more and more appli­ca­tions where bat­tery stor­age pays off.

What then stands in the way of expansion with battery storage?

One impor­tant ques­tion, is how the elec­tric­i­ty price zones with­in a net­work devel­op. Until four years ago, we still had a com­mon elec­tric­i­ty price zone with Aus­tria. This meant that Aus­tria bought its elec­tric­i­ty when elec­tric­i­ty prices were neg­a­tive. That was always the case when we had a lot of wind in the north. But since the trans­mis­sion lines from the North Sea to Aus­tria had too lit­tle trans­port capac­i­ty, this was solved via redis­patch. This means that the wind plants in the north were shut down and gas-fired pow­er plants in the south had to start up and pro­duce elec­tric­i­ty for Aus­tria at a neg­a­tive price. Now, with the sep­a­rate elec­tric­i­ty price zones, this no longer hap­pens. But we have this prob­lem with­in Ger­many as well. For exam­ple, the com­mon elec­tric­i­ty price zone allows Bavaria to buy cheap wind pow­er from the north, even though there is not enough trans­mis­sion line capac­i­ty to trans­port it. Then gas-fired pow­er plants have to start up in Bavaria and pro­duce this elec­tric­i­ty. And the costs for this are passed on to cus­tomers through­out Ger­many.

With different electricity price zones, electricity prices would be higher in southern Germany and lower in the north. What consequences would that have?

Elec­tric­i­ty prices would prob­a­bly vary sea­son­al­ly because we have more wind ener­gy in the north and more solar ener­gy in the south. High­er prices would def­i­nite­ly be an incen­tive to bet­ter match con­sump­tion to gen­er­a­tion and to store more elec­tric­i­ty. So there is already a strong case for invest­ing in ener­gy stor­age across the board to sup­port the fur­ther expan­sion of renew­ables


Prof. Bruno Burg­er is Senior Sci­en­tist at Europe’s largest solar research insti­tute, Fraun­hofer ISE, and cre­ator of the Ener­gy Charts.

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