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Nils Löhndorf

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Nils Löhndorf

Researcher of the Month

Im­prov­ing en­ergy stor­age ef­fi­ciency for cheaper re­new­able en­ergy

Due to the in­creased use of re­new­able en­ergy sources, the gen­er­a­tion of elec­tri­city is be­com­ing in­creas­ingly de­pend­ent on weather con­di­tions. En­ergy stor­age plants can be­ne­fit from this devel­op­ment by stor­ing power when it’s plen­ti­ful and selling it when sup­ply is lim­ited and the price goes up. The bet­ter sup­ply and de­mand are syn­chron­ized, the lower the price of elec­tri­city. Un­cer­tain weather con­di­tions cre­ate a di­lemma for stor­age plants, as they are in danger of miss­ing just the right mo­ment. Nils Löhndorf from WU’s In­sti­tute for Pro­duc­tion Man­age­ment has spent years devel­op­ing a de­cision-­mak­ing model to help solve this prob­lem. This model al­lows en­ergy sup­pli­ers to op­tim­ize the man­age­ment of com­plex stor­age sys­tems at times when prices and en­ergy sup­ply are un­cer­tain. Aus­trian en­ergy sup­pli­ers already keep an eye on Löhndorf’s re­search.

The European Union wants to cover 20% of its gross fi­nal en­ergy con­sump­tion us­ing re­new­able en­ergy sources by 2020. In Aus­tria, hy­dro­power plants have been in ex­tens­ive use for many dec­ades. Un­like solar and wind power, hy­dro­power can be stored in reser­voirs until needed. The vary­ing sup­ply of power from re­new­able sources is a ma­jor chal­lenge for the Aus­trian power stor­age in­dustry. Today, en­ergy is traded on en­ergy ex­changes throughout Europe. When wind en­ergy is plen­ti­ful, prices drop on the en­ergy ex­change; when sup­plies are low, prices rise. En­ergy stor­age pro­viders try to profit from these fluc­tu­ations by filling their stor­age plants when the price is down and re­leas­ing the en­ergy for sale when prices are higher. Aus­tria’s reser­voirs act as huge bat­ter­ies for re­new­able en­ergy from all over Europe. “Power com­pan­ies rely on fore­casts to de­cide on the op­timal time to buy and sell en­ergy. In­ac­cur­ate fore­casts can lead to losses for en­ergy pro­viders,” ex­plains WU Assist­ant Pro­fessor Nils Löhndorf. He de­cided to try and solve this prob­lem. After years of work, he has developed a de­cision-­mak­ing model based on scen­arios rather than fore­casts. This model al­lows power com­pan­ies to make bet­ter de­cisions when trad­ing their en­ergy.

More ef­fi­ciency = lower price

Löhndorf’s model al­lows users to take into ac­count a wide vari­ety of factors in the de­cision-­mak­ing pro­cess, in­clud­ing con­nec­ted reser­voirs, nat­ural in­flow, and vari­able prices. “The dif­fi­cult part is find­ing an op­timal solu­tion for all possible scen­arios, as the num­ber of scen­arios be­comes astro­nom­ic­ally huge the fur­ther into the fu­ture you try to plan. The method I developed re­duces the prob­lem size by ef­fi­ciently re­com­bin­ing scen­arios to com­pute an op­timal solu­tion,” says the re­searcher. This method has been in­teg­rated into the op­tim­iz­a­tion soft­ware QUASAR, already in use by Aus­trian en­ergy pro­viders to cal­cu­late when and how much en­ergy they should buy and sell on the en­ergy ex­change to be able to man­age their reser­voirs most ef­fi­ciently. Other coun­tries with a large stor­age ca­pa­city, for example Switzer­land, Nor­way, or Canada, could also be­ne­fit from the use of this soft­ware. “En­ergy stor­age is ex­pens­ive. The bet­ter we man­age our en­ergy stor­age sys­tems, the more af­ford­able elec­tri­city from sun, wind, and wa­ter will be­come,” says Löhndorf. “With ex­ist­ing stor­age sys­tems, a 5-10% in­crease in ef­fi­ciency is real­istic, while high-speed stor­age sys­tems like bat­ter­ies, whose out­put is traded on a ‘day-a­head’ basis, can ex­pect to profit con­sid­er­ably more.” Bet­ter stor­age man­age­ment also be­ne­fits con­sumers, as lower costs for pro­du­cers also res­ult in lower en­ergy prices for end users.

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