Scientists calculate the carbon footprint of grid-scale battery technologies

Mar 07, 2013 by Mark Shwartz
Solar and wind power pose a challenge for the U.S. electrical grid, which lacks the capacity to store surplus clean electricity and deliver it on demand. Researchers are developing grid-scale storage batteries, but the fossil fuel required to build these technologies could negate some of the environmental benefits of new solar and wind farms, say Stanford scientists. Credit: Dennis Schroeder / NREL

(Phys.org) —Americans take electrical power for granted whenever they flip on a light switch. But the growing use of solar and wind power in the United States makes the on-demand delivery of electricity more challenging.

A key problem is that the U.S. has virtually no , so grid operators can't stockpile surplus and deliver it at night, or when the wind isn't blowing.

To provide more flexibility in managing the grid, researchers have begun developing new batteries and other large-scale . But the fossil fuel required to build these technologies could negate some of the environmental benefits of installing new solar and , according to Stanford University scientists.

"We calculated how much it will cost society to build storage on future that are heavily supplied by ," said Charles Barnhart, a at Stanford's and (GCEP) and lead author of the study. "It turns out that that grid storage is energetically expensive, and some technologies, like lead-acid batteries, will require more energy to build and maintain than others."

The results are published in a recent online edition of the journal Energy & Environmental Science.

Most of the electricity produced in the United States comes from coal- and natural gas-fired power plants. Only about 3 percent is generated from wind, solar, hydroelectric and other renewable sources. The Stanford study considers a future U.S. grid where up to 80 percent of the electricity comes from renewables.

"Wind and solar power show great potential as low-carbon sources of electricity, but they depend on the weather," said co-author Sally Benson, a research professor of energy resource engineering at Stanford and the director of GCEP.

"As the percentage of electricity from these sources increases, grid operators will need energy storage to help balance supply with demand. To our knowledge, this study is the first to actually quantify the energetic costs of grid-scale storage over time."

Pumped hydro

The total storage capacity of the U.S. grid is less than 1 percent, according to Barnhart. What little capacity there is comes from pumped hydroelectric storage, a clean, renewable technology. Here's how it works: When demand is low, surplus electricity is used to pump water to a reservoir behind a dam. When demand is high, the water is released through turbines that generate electricity.

For the Stanford study, Barnhart and Benson compared the amount of energy required to build a pumped hydro facility with the energetic cost of producing five promising battery technologies: lead-acid, lithium-ion, sodium-sulfur, vanadium-redox and zinc-bromine.

"Our first step was to calculate the cradle-to-gate embodied energy," Barnhart said. "That's the total amount of energy required to build and deliver the technology – from the extraction of raw materials, such as lithium and lead, to the manufacture and installation of the finished device."

To determine the amount of energy required to build each of the five battery technologies, Barnhart relied on data collected by Argonne National Laboratory and other sources. The data revealed that all five batteries have high embodied-energy costs compared with pumped hydroelectric storage.

"This is somewhat intuitive, because battery technologies are made out of metals, sometimes rare metals, which take a lot of energy to acquire and purify," Barnhart said. "Whereas a pumped hydro facility is made of air, water and dirt. It's basically a hole in the ground with a reinforced concrete dam."

After determining the embodied energy required to build each storage technology, Barnhart's next step was to calculate the energetic cost of maintaining the technology over a 30-year timescale. "Ideally, an energy storage technology should last several decades," he said. "Otherwise, you'll have to acquire more materials, rebuild the technology and transport it. All of those things cost energy. So the longer it lasts, the less energy it will consume over time as a cost to society."

To quantify the long-term energetic costs, Barnhart and Benson came up with a new mathematical formula they dubbed ESOI, or energy stored on investment. "ESOI is the amount of energy that can be stored by a technology, divided by the amount of energy required to build that technology," Barnhart said. "The higher the ESOI value, the better the storage technology is energetically."

When Barnhart crunched the numbers, the results were clear. "We determined that a pumped hydro facility has an ESOI value of 210," he said. "That means it can store 210 times more energy over its lifetime than the amount of energy that was required to build it."

The five battery technologies fared much worse. Lithium-ion batteries were the best performers, with an ESOI value of 10. Lead-acid batteries had an ESOI value of 2, the lowest in the study. "That means a conventional lead-acid battery can only store twice as much energy as was needed to build it," Barnhart said. "So using the kind of lead-acid batteries available today to provide storage for the worldwide power grid is impractical."

Improved cycle life

The best way to reduce a battery's long-term energetic costs, he said, would be to improve its cycle life – that is, increase the number of times the battery can charge and discharge energy over its lifetime. "Pumped hydro storage can achieve more than 25,000 cycles," Barnhart said. "That means it can deliver clean energy on demand for 30 years or more. It would be fantastic if batteries could achieve the same cycle life."

None of the conventional featured in the study has reached that level. Lithium-ion is the best at 6,000 cycles, while lead-acid technology is at the bottom, achieving a mere 700 cycles.

"The most effective way a storage technology can become less energy-intensive over time is to increase its cycle life," Benson said. "Most battery research today focuses on improving the storage or power capacity. These qualities are very important for electric vehicles and portable electronics, but not for storing energy on the grid. Based on our ESOI calculations, grid-scale battery research should focus on extending cycle life by a factor of 3 to 10."

In addition to energetic costs, Barnhart and Benson also calculated the material costs of building these grid-scale storage technologies.

"In general, we found that the material constraints aren't as limiting as the energetic constraints," Barnhart said. "It appears that there are plenty of materials in the Earth to build energy storage. There are exceptions, such as cobalt, which is used in some lithium-ion technologies, and vanadium, the key component of vanadium-redox flow batteries."

Pumped hydro storage faces another set of challenges. "Pumped hydro is energetically quite cheap, but the number of geologic locations conducive to pumped hydro is dwindling, and those that remain have environmental sensitivities," Barnhart said.

The study also assessed a promising technology called CAES, or compressed air energy storage. CAES works by pumping air at very high pressure into a massive cavern or aquifer, then releasing the compressed air through a turbine to generate electricity on demand. The Stanford team discovered that CAES has the fewest material constraints of all the technologies studied, as well as the highest ESOI value: 240. Two CAES facilities are operating today in Alabama and Germany.

Global warming impact

A primary goal of the study was to encourage the development of practical technologies that lower greenhouse emissions and curb global warming, Barnhart said. Coal- and natural gas-fired power plants are responsible for at least a third of those emissions, and replacing them with emissions-free technologies could have a dramatic impact, he added.

"There are a lot of benefits of electrical energy storage on the power grid," he said. "It allows consumers to use power when they want to use it. It increases the amount of energy that we can use from wind and solar, which are good low-carbon sources."

In November 2012, the U.S. Department of Energy launched the $120 million Joint Center for Energy Storage Research, a nationwide effort to develop efficient and reliable storage systems for the grid. The center is led by Argonne National Laboratory in partnership with the SLAC National Accelerator Laboratory at Stanford and a dozen other institutions and corporations. Part of the center's mission is to develop new battery architectures that improve performance and increase cycle life – a direction that Barnhart and Benson strongly support.

"I would like our study to be a call to arms for increasing the cycle life of electrical energy storage," Barnhart said. "It's really a basic conservative principal: The longer something lasts, the less energy you're going to use. You can buy a really well-made pair of boots that will last five years, or a shoddy pair that will last only one."

Explore further: Many tongues, one voice, one common ambition

More information: pubs.rsc.org/en/content/articl… g/2013/ee/c3ee24040a

Related Stories

Compressed Air Energy Storage: Renewable Energy

Mar 17, 2010

(PhysOrg.com) -- Wind-power turbines have played an important step in renewable energy but now the future of wind power may be underground. By using compressed-air energy storage plants, air is pumped into ...

UM invention helps advance reliability of alternative energy

Apr 16, 2012

A University of Minnesota invention could help make storage of solar and wind energy more efficient and economical. The invention was licensed to SustainX, a leading global developer of grid-scale energy storage solutions ...

From the rustbelt: An iron-based flow battery

May 25, 2011

Researchers at Case Western Reserve University are mixing cheap and plentiful iron in benign solutions to create a flow battery – essentially an unwrapped battery that can be scaled up to hold and supply electricity ...

Recommended for you

Many tongues, one voice, one common ambition

10 hours ago

There is much need to develop energy efficient solutions for residential buildings in Europe. The EU-funded project, MeeFS, due to be completed by the end of 2015, is developing an innovative multifunctional and energy efficient ...

Panasonic, Tesla to build big US battery plant

11 hours ago

(AP)—American electric car maker Tesla Motors Inc. is teaming up with Japanese electronics company Panasonic Corp. to build a battery manufacturing plant in the U.S. expected to create 6,500 jobs.

Simulation models optimize water power

12 hours ago

The Columbia River basin in the Pacific Northwest offers great potential for water power; hydroelectric power stations there generate over 20 000 megawatts already. Now a simulation model will help optimize the operation ...

Charging electric cars efficiently inductive

12 hours ago

We already charge our toothbrushes and cellphones using contactless technology. Researchers have developed a particularly efficient and cost-effective method that means electric cars could soon follow suit.

User comments : 32

Adjust slider to filter visible comments by rank

Display comments: newest first

praos
2.2 / 5 (13) Mar 07, 2013
Adding nonsense to injury. Go nuclear and skip all those problems. It's pure rape of Mother Nature: forcing upon her a technology she evidently abhors. Greens are her suitors; their love is obviously not reciprocated. End of story, stop stalking her.
Job001
1.9 / 5 (9) Mar 07, 2013
Adding nonsense to injury. Go nuclear and .

Pure FUD, it's all about economics and this anti green scarcity nonsense supporting natural utility monopolies doesn't cut it. Grids will adapt, solar and wind will adapt, let the free market win, not these FUD scarcity monopolistic profiteers.
Modernmystic
2.7 / 5 (7) Mar 07, 2013
I wonder if this huge infrastructure investment is included in the costs of such "cheap" renewables....

OTOH we already have a carbon free technology which doesn't require such jury rigging to be practical....
Steambop
4.7 / 5 (3) Mar 07, 2013
I would if the true cost of the damage that fossil fuels are having on our environment and our health are included in the costs of such "conventional" technologies...
joefarah
2 / 5 (3) Mar 07, 2013
I guess Altairnano battery technology would have and ESOI of about 25 to 50, given it's ability to recharge 10s of thousands of times with little degradation.
My guess is that to increase ESOI values, the best approach is to decrease the energy required to build the battery. I would expect we could approach an order of magnitude if we put out minds to it.
antialias_physorg
3.9 / 5 (8) Mar 07, 2013
and some technologies, like lead-acid batteries, will require more energy to build and maintain than others.

Lead acid batteries as grid stability technology? Really? I mean: Seriously? Why even compute the ecological cost for a nonsense solution?
packrat
1.2 / 5 (5) Mar 07, 2013
and some technologies, like lead-acid batteries, will require more energy to build and maintain than others.

Lead acid batteries as grid stability technology? Really? I mean: Seriously? Why even compute the ecological cost for a nonsense solution?


Why not? commercial type lead acid batteries are completely recyclable and as more and more electric vehicles hit the roads there are going to be more and more car batteries that will need to be recycled and the lead reused. They are not the most efficient batteries out there true but they are about the cheapest and if taken care of properly can last for years.
kochevnik
3.3 / 5 (7) Mar 07, 2013
@praos Adding nonsense to injury. Go nuclear and skip all those problems.
Nuclear requires large cooling ponds. Larger than hydropumping. Unlike hydropumping, nuclear produces heat pollution. This makes the water uninhabitable. Moreover nuclear is a magnet for terrorists
Eikka
3.7 / 5 (3) Mar 07, 2013
Lead acid batteries as grid stability technology? Really? I mean: Seriously? Why even compute the ecological cost for a nonsense solution?


Because in the grand renewable future, you're going to have to pretty much scrape all the way to the bottom of the barrel to get it all working.

It's not going to be just hydro storage or CAES or lithium batteries all the way, because none of them alone come even close to the amounts of energy you need to store in order to maintain the grid with 100% renewable energy on a daily, monthly and yearly timescale.

And they're already in use in just that purpose. People with homes off the grid need batteries, and deep cycle lead acid batteries do the job for a reasonable amount of money.
Eikka
1.3 / 5 (3) Mar 07, 2013
They are not the most efficient batteries out there true but they are about the cheapest and if taken care of properly can last for years.


There are lead acid cell types that approach nickel cadmium in energy density, which means less lead used per unit energy, and about twice the ESOI.

In theory, lead acid batteries could hold 120-150 Wh/kg which is roughly equal to midrange lithium ion batteries, but they only do about 30-40 because of the traditional form factor in car batteries, which have poor utilization of the active material in exchange for robustness. With a different cell design, you can push it to 50-60 Wh/kg.
djr
5 / 5 (2) Mar 07, 2013
"Most of the electricity produced in the United States comes from coal- and natural gas-fired power plants. Only about 3 percent is generated from wind, solar, hydroelectric and other renewable sources."
If the authors cannot get a basic fact like this correct - I would not place much faith in the rest of their work. This number (3%) sounded very low to me - and a quick google search suggested the number is closer to 15%. Does any one have more in depth information?

http://en.wikiped...d_States

I think maybe they meant to say wind turbines produce around 3% - but if you don't immediately recognize that size of an error - you should not be writing on this subject.
antialias_physorg
3 / 5 (4) Mar 08, 2013
Maybe they meant 'energy produced' instead of 'electricity produced'. But even then it's closer to 7.3% and not 3%
http://en.wikiped...neration

But yeh: The article seems to be beased on some weird numbers and is looking at a weird (and weirdly limited) subset of available technologies.
Uzza
1 / 5 (2) Mar 08, 2013
Is it just me that reacted to the fact that the headlines says "Scientists calculate the carbon footprint of grid-scale battery technologies", but in the article body there is not a single mention of the carbon footprint, only the ESOI value which is not the same thing.
JRi
1 / 5 (3) Mar 08, 2013
Maybe it is the demand that will change it's behavior with green energy, solar and wind. When the price of electricity will skyrocket during night time or non-windy days, people and industry will decrease their electricity usage.
Modernmystic
2.3 / 5 (3) Mar 08, 2013
Nuclear requires large cooling ponds. Larger than hydropumping.


Really? How large is the volume on which types of reactors? How large is the volume of your typical hydropumping system being proposed? Let's see the numbers and sources...

Moreover you can use towers or ponds, it's not a given in every design :)

Unlike hydropumping, nuclear produces heat pollution. This makes the water uninhabitable.


But fish can live in the water and volume of the hydropumping stations? Interesting...

Moreover nuclear is a magnet for terrorists


Eco terrorists maybe...I don't know of an incident that was any more significant than any other type of power plant. If you have one list it...
kochevnik
2.4 / 5 (5) Mar 09, 2013
@MM Eco terrorists maybe...I don't know of an incident that was any more significant than any other type of power plant. If you have one list it...
How did that strategy work out for you on 9/11?
Mannstein
1 / 5 (1) Mar 09, 2013
Excess electrical power could be turned into hydrogen using water electrolysers. The hydrogen stored on site could then be burned in a gas turbine gen set when power is needed on cloudy or windless days . The exhaust which is water vapor condensed and returned to be reused. Electrolysers have longer life than even the best batteries.
Steven_Anderson
1 / 5 (3) Mar 10, 2013
Conventional nuclear has a huge waste problem. It is a target for terrorists around the world. That is not a show stopper because Uranium reactors are a dinosaur. We have the technology to build generation 4 reactors which are almost impossible to use for proliferation. That is because they do not use Uranium accept the spent Uranium (which as you know we have huge stock piles of) to start off the reaction. The technology is called LFTR nuclear reactors. India will have their first large scale LFTR reactor working NEXT year. It's a 500MWe reactor. Within a few years 6 others will follow. LFTR
Steven_Anderson
1.6 / 5 (5) Mar 10, 2013
Take a look at my article India Full Scale LFTR .http://rawcell.co...-online/
Lilly Anne
2.3 / 5 (3) Mar 11, 2013
@ModernMystic: Eco terrorists maybe...I don't know of an incident that was any more significant than any other type of power plant. If you have one list it...
How did that strategy work out for you on 9/11?

Kochevnik: What do you mean by that? How did WHAT strategy work out for whom on 9/11?

There hasn't been a preponderance of nuclear terrorism to which the USA has been subject, not that I am aware of. In fact, nuclear terrorism hasn't been an especially significant problem anywhere. In Iran, due to Stuxnet, there was sabotage but no intent to harm by release of ionizing radiation. I am probably the only person in the USA who thinks that Iran is sensible for developing nuclear power plants. Just because they use nuclear power as an alternative to fossil fuel doesn't imply they'll decide to drop nuclear bombs on anyone.

Regarding 9/11: The commercial aircraft that were misused in that tragedy were not nuclear powered. So I don't understand the logic in your comment.
antialias_physorg
2 / 5 (4) Mar 11, 2013
Eco terrorists maybe

For all the (media) talk on eco-terrorists: Does anyone have any sources of there ever existing an eco-terrorist action (or even any group claiming to even want to attempt eco-terrorist activities)?

What EXACTLY qualifies one as an eco-terrorist? (and please use some definition of TERROR in your answer. Not just some gut-feeling-"should-be-like-this" definition)

I am probably the only person in the USA who thinks that Iran is sensible for developing nuclear power plants.

And we should not forget that any nation has the right to develop nuclear technology if they want to according to all international treaties out there.
People may not like Iran or Iranian politics (and I certainly am not patricularly fond of it), but that still doesn't mean there is any grounds for getting all fired up over them doing what it is their right to do.
Lilly Anne
1 / 5 (1) Mar 11, 2013
The article says:
Solar and wind power pose a challenge for the U.S. electrical grid, which lacks the capacity to store surplus clean electricity and deliver it on demand... The total storage capacity of the U.S. grid is less than 1%.
Do electrical grids in other countries have greater than 1% storage capacity for extra clean energy? If so, why don't we use a similar approach?
Modernmystic
1 / 5 (3) Mar 11, 2013
Do electrical grids in other countries have greater than 1% storage capacity for extra clean energy? If so, why don't we use a similar approach?


Because of the added infrastructure costs?
Modernmystic
1 / 5 (3) Mar 11, 2013
For all the (media) talk on eco-terrorists: Does anyone have any sources of there ever existing an eco-terrorist action (or even any group claiming to even want to attempt eco-terrorist activities)?


http://en.wikiped..._tactics

Pay close attention to the last example given in 1982 :)
antialias_physorg
2 / 5 (4) Mar 11, 2013


http://en.wikiped..._tactics

Pay close attention to the last example given in 1982

Oh wow.
That really sounds like global threat level purple-orange-red-ultraviolet is merited. And the most recent of these actions is only 30 years old, too. That's just like...yesterday! Evereyone run and hide! (/sarcasm)
Modernmystic
1 / 5 (3) Mar 11, 2013


http://en.wikiped..._tactics

Pay close attention to the last example given in 1982

Oh wow.
That really sounds like global threat level purple-orange-red-ultraviolet is merited. And the most recent of these actions is only 30 years old, too. That's just like...yesterday! Evereyone run and hide! (/sarcasm)


Those were some examples, not all of them. Moreover you wanted some examples, I provided them. If you're going to act like a child when someone complies with a request don't count on your requests getting due attention in the future.
antialias_physorg
2.3 / 5 (3) Mar 11, 2013
Yes, you did provide example. So yes: there were eco-terrorists (operative word being 'were'). And my post did not deride THAT you found something (which I think is cool) but WHAT you found.

But I'm quite sure that none of the arguments about eco-terrorists floating around on this site (or in the media) even remotely refer to the groups you linked to (or groups like them).
They just seem to bandy the word around for anyone who is even minimally ecology-conscious. And that is NOT terrorism.

don't count on your requests getting due attention in the future.

Whatever will I do now? You not paying attention to my requests? Oh woe is me. I am undone.
Modernmystic
1 / 5 (3) Mar 11, 2013
Yes, you did provide example. So yes: there were eco-terrorists (operative word being 'were').


No there ARE, if you bothered to read the entire article.

They just seem to bandy the word around for anyone who is even minimally ecology-conscious. And that is NOT terrorism.


If you threaten to use physical force to further an environmentally based activist issue then YES it is terrorism.


Whatever will I do now? You not paying attention to my requests? Oh woe is me. I am undone.


Do you own research? Get some insight and introspection without expecting others to do it? Just some suggestions.
antialias_physorg
2.3 / 5 (3) Mar 11, 2013
If you threaten to use physical force to further an environmentally based activist issue then YES it is terrorism.

And sinec no one who is arguing for a changeover is advocating violence (just good old democratic principles.) Where's the problem?

Wanting to set up windmills or photovoltaics is NOT terrorism.
Showing up at non-violent protests is NOT terrorism. Even if demonstrations result in scuffles with the police that is STILL not terrorism.
Being vocal about wanting a changeover is NOT terrorism.

Therefore people should just stop using those words in arguments unless they are referring to those dozen guys in the world who spike tress with nails.
Modernmystic
1 / 5 (3) Mar 11, 2013
And sinec no one who is arguing for a changeover is advocating violence (just good old democratic principles.) Where's the problem?


No one? Well there obviously are some people. Are you saying no one on this forum? I'd even have to disagree with that as I've seen some posters here advocating violence in the name of AGW. Are you saying no one in THIS conversation...well no DUH.

That's NOT what we're talking about here though. WE were talking about terrorism in general and the likelihood of terrorist attacks (re-read up thread). I've no clue what YOU'RE talking about, or why you seem to be taking this so personally....

Take a deep breath and dial your "it's all about me" meter down a few notches.
antialias_physorg
2.3 / 5 (3) Mar 12, 2013
Well there obviously are some people.

Like?

I'm sure there are some people who are willing to use violenec to keep others off their lawn. Is therefore everyone who doesn't want someone else on their front lawn a 'lawn-terrorist'?

I'd even have to disagree with that as I've seen some posters here advocating violence in the name of AGW.

Link, please. I've been here quite a while - but I have not yet seen anyone who advocated killing and/or sabotaging of power infrastructure to combat AGW.

WE were talking about terrorism in general

Then you shouldn't have responded to MY post which was not about nuclear terrorism but the mention of eco terrorism.

I've no clue what YOU'RE talking about

Obviously. Reading comprehension is a lost art.
Modernmystic
1 / 5 (2) Mar 12, 2013
Then you shouldn't have responded to MY post which was not about nuclear terrorism but the mention of eco terrorism.


Which is part of terrorism in general. See this is how terrorism is viewed in GENERAL. You have militant Islamist, Catholics (IRA), right wing militia, left wing militia, AND those who commit acts of violence in the name of "the environment" etc. etc. etc... YOU shouldn't have responded to my post about terrorism if you were worried about equivocation or some personal issue I'm not privy to.