Why bat­ter­ies are vi­tal in the fight against cli­mate change

By Adam Vaughan and Sa­muel Gibbs The vari­able na­ture of wind and so­lar power means stor­ing en­ergy is a huge part of the fight to mit­i­gate cli­mate change

The Guardian - Journal - - Front page -

Why have bat­ter­ies be­come im­por­tant?

In a world in­creas­ingly anx­ious about cli­mate change, the surge in the gen­er­a­tion of re­new­able en­ergy over the past 20 years of­fers a sliver of hope. But the vari­able na­ture of wind and so­lar power means that stor­ing en­ergy un­til con­sumers need it has be­come the next big chal­lenge. And so, large-scale bat­tery in­stal­la­tions are spring­ing up across elec­tric­ity grids around the world, to make them more flex­i­ble. In 2017, more than 1GW of en­ergy stor­age ca­pac­ity was added around the world – a record, yes, but still a drop in the ocean of global en­ergy de­mand.

How do bat­ter­ies like this work?

Of course, we are not talk­ing about a few AAA bat­ter­ies here. And yet, all bat­ter­ies broadly work in a sim­i­lar man­ner.

Elec­tri­cal en­ergy is con­verted to chem­i­cal en­ergy when you charge a bat­tery, and then the process is re­versed when you draw power from it. There are three main con­stituents of most bat­ter­ies: two elec­trodes and some form of chem­i­cal medium called the elec­trolyte, which can be a liq­uid, gel or solid. To gen­er­ate elec­tric­ity, a chem­i­cal re­ac­tion takes place that sees elec­trons move from the neg­a­tive elec­trode, called the an­ode, to the pos­i­tive elec­trode, called the cath­ode.

When you charge the bat­tery, the process is re­versed, send­ing elec­trons back to the an­ode.

So how many of these big bat­ter­ies are there?

There is about 500MW of large-scale bat­tery ca­pac­ity in­stalled around the UK, a fig­ure that is ex­pected to dou­ble within three years, ac­cord­ing to the an­a­lysts Aurora En­ergy Re­search. Al­most all ca­pac­ity uses lithium-ion.

Glob­ally in­stalled ca­pac­ity is ex­pected to top 50GW by 2020 – and surge to al­most 1,000GW by 2040, ac­cord­ing to Bloomberg New En­ergy Fi­nance. That would equate to about 7% of the world’s en­ergy ca­pac­ity.

How do bat­ter­ies fit in to the re­new­ables rev­o­lu­tion?

In the UK, bat­tery in­stal­la­tions are pri­mar­ily be­ing de­ployed to sup­ply ser­vices to Na­tional Grid. Such an­cil­lary ser­vices are in­creas­ingly im­por­tant to help match sup­ply and de­mand as a grow­ing amount of in­ter­mit­tent wind and so­lar power comes on­line.

There are also the be­gin­nings of “hy­brid” re­new­able en­ergy power plants, where bat­ter­ies are in­stalled along­side so­lar farms and wind­farms. This is par­tic­u­larly im­por­tant for the eco­nomics of so­lar farms, which can push down power prices around mid­day by peak­ing at the same time. In­stead of ex­port­ing im­me­di­ately, hy­brid farms can store power to sell later at higher prices.

In other parts of the world, such as South Aus­tralia, bat­ter­ies are be­ing used to make the grid more re­silient and avoid black­outs. Cru­cially, bat­ter­ies are not yet suitable and do not make eco­nomic sense for in­ter­sea­sonal stor­age – that is, stor­ing up so­lar power in sum­mer to re­lease in win­ter.

Will we all have big house­hold bat­ter­ies in the fu­ture?

Elon Musk may have pop­u­larised the con­cept of a home bat­tery when he un­veiled Tesla’s ver­sion three years ago, but the firm was not the first and is not the big­gest in this field. Such bat­ter­ies, which are about the size of a gas boiler, can store and re­lease elec­tric­ity ei­ther gen­er­ated by a house­hold or im­ported from the grid.

The Ger­man firm Son­nen, which has about a 25% global mar­ket share in home bat­ter­ies, said most cus­tomers to­day are peo­ple who have so­lar pan­els or live in storm-hit re­gions and want a clean, re­li­able backup source of power. “The mar­ket is still in the very, very early phase,” says the chief ex­ec­u­tive, Christoph Oster­mann. Ger­many, Italy, Aus­tralia and the US states of Cal­i­for­nia and Hawaii are the big­gest mar­kets so far.

For so­lar house­holds, it makes more fi­nan­cial sense to store and con­sume the en­ergy rather than be paid for ex­port­ing it to the grid. In fu­ture, as more time-of-use en­ergy tar­iffs emerge, there might also be enough of an in­cen­tive to in­stall one to avoid peak pric­ing.

How­ever, for Oster­mann, the most ex­cit­ing prospect is har­ness­ing thou­sands of the bat­ter­ies as a “vir­tual power plant”. He de­scribes this as an “Uberi­sa­tion” of bat­ter­ies that the com­pany does not own but can call on, with per­mis­sion. “We

What’s next for elec­tric cars?

We are just be­gin­ning to see the sec­ond gen­er­a­tion of bat­tery­pow­ered ve­hi­cles, ac­cord­ing to the en­tre­pre­neur Hen­rik Fisker, the founder of the elec­tric car maker Fisker Au­to­mo­tive. He views af­ford­abil­ity and a de­cent range be­tween charges as this crop’s defin­ing fea­tures.

While the first models, with the ex­cep­tion of Tesla, could man­age about 100 miles, most new ones now of­fer be­tween 200-300 miles. “I see the mar­ket start­ing to boom about 2020 or 2021, as there is more choice [of models],” says Fisker.

Fisker also views ul­tra­fast charg­ing as vi­tal to help­ing elec­tric cars go main­stream. While a typ­i­cal home will take about 8-10 hours to fully top up a car (with a 3KW socket), some new pub­lic charg­ers can do that in about 10 min­utes (us­ing a 350KW charger).

What about other modes of trans­port?

Elec­tric dou­ble-decker buses, built by the Chi­nese man­u­fac­turer BYD, al­ready ply the streets of Lon­don. Elon Musk has an­nounced plans for an elec­tric truck.

But the en­ergy den­sity re­quired for heavy trans­port makes it a lot harder for bat­ter­ies to beat fos­sil fu­els. “It’s def­i­nitely more chal­leng­ing,” says Prof Paul Shearing, the Royal Academy of En­gi­neer­ing’s chair in emerg­ing bat­tery tech­nolo­gies. “[But] I think the fu­ture is go­ing to be elec­tric, no mat­ter which way you cut it.”

Will we all be fly­ing around in elec­tric jumbo jets soon?

“Not yet,” says Shearing, who adds that en­ergy den­sity and weight of bat­ter­ies meant there would prob­a­bly only be used in un­manned ae­rial ve­hi­cles in the short term. “I think it’ll be a long time un­til we see an elec­tric pas­sen­ger plane,” he says.

‘UK large-scale bat­tery ca­pac­ity is ex­pected to dou­ble within three years’

are not head­ing for util­ity scale, but vir­tual power plants can pro­vide sig­nif­i­cant power,” he says.

What is the en­vi­ron­men­tal and so­cial im­pact of mak­ing bat­ter­ies? A key el­e­ment in lithium-ion bat­ter­ies is cobalt, de­spite man­u­fac­tur­ers’ at­tempt to re­duce the amount re­quired. More than

60% world’s cobalt is pro­duced in the Demo­cratic Repub­lic of Congo, where con­cerns have been raised about the so­cial and en­vi­ron­men­tal im­pact of min­ing the metal.

The lithium in the bat­ter­ies comes mainly from three big pro­ducer coun­tries, Aus­tralia, Ar­gentina and Chile, along with emerg­ing pro­duc­ers such as Bo­livia, Brazil, Canada and Zim­babwe. Wa­ter con­sump­tion and scarcity in some pro­ducer coun­tries is the big con­cern here. “There are def­i­nite ethics is­sues. Large com­pa­nies are go­ing to be driven by cost,” says Shearer, of cobalt and lithium pro­duc­tion.

What hap­pens to the bat­ter­ies to­wards the end of their life is also a big chal­lenge. Dr Jonathan Rad­cliffe, of the school of chem­i­cal en­gi­neer­ing at the Univer­sity of Birm­ing­ham, is wor­ried about the fate of bat­ter­ies when their per­for­mance in to­day’s crop of elec­tric ve­hi­cles is no longer good enough for cars. Some now have a sec­ond life as a home bat­tery, but he fears the mar­ket could be sat­u­rated in a few years, un­der­min­ing the fi­nan­cial case for re­use.

“The risk is that there is no vi­able sec­ond-use in the UK and we have a large amount of bat­tery waste, with­out the pro­cesses in place to deal with it,” he says.

What lim­its ca­pac­ity and bat­tery life?

The big­ger and denser the bat­tery, the more chem­i­cal en­ergy it can store and there­fore the more elec­tric­ity it can gen­er­ate. But a big­ger, denser bat­tery is more ex­pen­sive, heav­ier, takes longer to charge and has more po­ten­tial for de­struc­tion if things go wrong.

The chem­istry and in­ter­nal con­struc­tion of the bat­tery also plays a role in how much en­ergy it can store. Lithium-based bat­ter­ies are pop­u­lar be­cause they have a rel­a­tively high en­ergy-to-weight ra­tio and main­tain their charge well when not in use.

In most de­vices, bat­tery life is a trade-off be­tween phys­i­cal size, de­sign, en­ergy den­sity and safety, along­side the en­ergy ef­fi­ciency of the de­vice it pow­ers.

What about phone bat­ter­ies – why do they de­te­ri­o­rate as they get old? Most bat­ter­ies can only main­tain their full ca­pac­ity for a fi­nite time and num­ber of charge and dis­charge cy­cles. The ex­act process of bat­tery age­ing is still a hot re­search topic, but there are sev­eral mech­a­nisms at play that oc­cur when the bat­tery is used or stored.

The most com­mon is the build-up of ma­te­rial on the an­ode, which slowly gets de­posited when the bat­tery is used or stored. A sim­i­lar ox­i­da­tion can also oc­cur on the cath­ode, while the ac­tive in­gre­di­ents of the bat­tery can re­act and de­grade over time. A com­bi­na­tion of these ef­fects re­duce the amount of ions and ac­tive ma­te­rial avail­able for stor­ing elec­tric­ity, there­fore re­duc­ing max­i­mum ca­pac­ity.

But the in­ter­nal re­sis­tance of the bat­tery can also in­crease as it ages, mean­ing its peak power out­put is lower, a process that causes is­sues in iPhones.

What ac­cel­er­ates bat­tery age­ing?

How a bat­tery is used and stored can dra­mat­i­cally af­fect its age­ing. For in­stance, bat­ter­ies can be dam­aged by ex­pos­ing them to ex­tremes of tem­per­a­ture, which is more prob­lem­atic for a car or sim­i­lar than a smart­phone.

Rapid cy­cling of the bat­tery also in­creases wear, par­tic­u­larly if the power de­mands on the bat­tery are very high, as is the case with elec­tric cars. Charg­ing and us­ing the bat­tery to its ex­tremes also ac­cel­er­ates age­ing, such as charg­ing bat­ter­ies to their max­i­mum and dis­charg­ing them to zero.

What hap­pens if things go wrong?

Safety was thrown into the spot­light when some of the bat­ter­ies in­side the Sam­sung Galaxy Note 7 de­vel­oped a fault that caused them to short cir­cuit and catch fire.

When some­thing dis­rupts the chem­i­cal re­ac­tion in­side the bat­tery, it can cause “ther­mal ru­n­away”, where un­con­trolled re­ac­tions chain to­gether, gen­er­at­ing too much heat, typ­i­cally re­sult­ing in bat­ter­ies burst­ing or catch­ing fire.

Var­i­ous safety mech­a­nisms, both elec­tri­cal con­trol cir­cuits and phys­i­cal mea­sures in­clud­ing shield­ing and bat­tery struc­ture, mean such events are rare. But they are of par­tic­u­lar con­cern for por­ta­ble de­vices, which are of­ten held on a per­son, and elec­tric ve­hi­cles that may be in­volved in a col­li­sion that could dam­age the in­tegrity of the bat­tery.

What next?

Com­pa­nies are work­ing hard to in­crease the amount of en­ergy that can be packed into a bat­tery, and to bring down the cost of mak­ing them.

Fu­ture prices are un­likely to fall as fast as they have in the past, says Oster­mann, be­cause re­duc­tions have al­ready been so rapid. Son­nen has seen prices fall from more than €1,000 (£905) per kilo­watt hour of ca­pac­ity when it started in 2010, to about €150-200 per kWh to­day. But the com­pany ex­pects to cut costs in elec­tron­ics such as in­vert­ers.

New won­der ma­te­ri­als will take a while to break through, Shearer says. “The next 10 years are go­ing to con­tinue to be lithi­u­mion dom­i­nated. It’s taken a long time to get to this pro­duc­tiv­ity and tech­no­log­i­cal ma­tu­rity level.

For any­thing to catch up will take a while.”

Most in­no­va­tion will be around lithium-ion, he be­lieves, such as im­prov­ing the en­ergy den­sity and low­er­ing costs by re­duc­ing the amount of cobalt in a bat­tery. The rate at which bat­ter­ies can take on a charge will also im­prove, Shearer adds.

Rad­cliffe agrees that lithium-ion will con­tinue to dom­i­nate. Cost and per­for­mance will im­prove, driven by the scale-up of man­u­fac­tur­ing and con­tin­ued re­search, he says.

Bat­ter­ies will also be put to new uses. Fisker says that as tech­nol­ogy im­proves, he ex­pects to see them even­tu­ally ap­pear on con­struc­tion sites, in mines and in in­dus­trial equip­ment, re­plac­ing diesel gen­er­a­tors. They will be de­ployed in in­creas­ingly small de­vices, such as med­i­cal im­plants, Shearer says.

‘Sam­sung Galaxy Note 7 bat­ter­ies de­vel­oped a fault that caused them to catch fire’

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