From Stanford University
Stanford scientists calculate the energy required to store wind and solar power on the grid
Renewable energy holds the promise of reducing carbon dioxide emissions. But there are times when solar and wind farms generate more electricity than is needed by consumers. Storing that surplus energy in batteries for later use seems like an obvious solution, but a new study from Stanford University suggests that might not always be the case.
“We looked at batteries and other promising technologies for storing solar and wind energy on the electrical grid,” said Charles Barnhart, the lead author of the study and a postdoctoral scholar at Stanford’s Global Climate and Energy Project (GCEP).
“Our primary goal was to calculate their overall energetic cost – that is, the total amount of fuel and electricity required to build and operate these storage technologies. We found that when you factor in the energetic costs, grid-scale batteries make sense for storing surplus solar energy, but not for wind.”
The study, which is supported by GCEP, is published in the online edition of the journal Energy and Environmental Science.
Climate change and renewable energy
Most electricity in the United States is generated at power plants that run on coal and natural gas – fossil fuels that contribute significantly to global warming by emitting large amounts of carbon dioxide. Solar and wind power are emissions-free and renewable, but depend on sunlight or wind to operate.
“For the grid to function efficiently, power supply needs to match power demand at all times, but with renewables, that’s not always the case,” Barnhart said. “For example, wind farms sometimes produce too much electricity at night when demand is low. That excess energy has to be stored or used elsewhere. Otherwise it will be lost. However, the U.S. grid has very limited storage capacity.”
A wide variety of technologies are being developed to address the lack of grid-scale storage. The Stanford team looked at several emerging technologies, including five battery types – lead-acid, lithium-ion, sodium-sulfur, vanadium-redox and zinc-bromine.
In a previous study, Barnhart calculated the energetic cost of building and maintaining each of the five battery systems for grid-scale storage. Lead-acid batteries had the highest energetic cost, lithium-ion the lowest, he found.
“We calculated how much energy is used over the full lifecycle of the battery – from the mining of raw materials to the installation of the finished device,” Barnhart said. “Batteries with high energetic cost consume more fossil fuels and therefore release more carbon dioxide over their lifetime. If a battery’s energetic cost is too high, its overall contribution to global warming could negate the environmental benefits of the wind or solar farm it was supposed to support.”
For this study, he and his colleagues calculated the energetic cost of grid-scale photovoltaic solar cells and wind turbines.
“Both wind turbines and photovoltaics deliver more energy than it takes to build and maintain them,” said GCEP postdoctoral scholar Michael Dale, a co-author of the study. “However, our calculations showed that the overall energetic cost of wind turbines is much lower than conventional solar panels, which require lots of energy, primarily from fossil fuels, for processing silicon and fabricating other components.”
To store or curtail?
Next the scientists looked at the energetic cost of curtailment – the practice of shutting down solar panels and wind turbines to reduce the production of surplus electricity on the grid.
“Curtailment of renewable resources seems wasteful,” Barnhart said. “But grid operators routinely curtail wind turbines to avoid a sudden, unexpected surge of excess electricity that could overload transmission lines and cause blackouts. Curtailment rates in the U.S. will likely increase as renewable energy becomes more prevalent.”
Shutting down a clean source of electricity seems counterproductive, but is storing surplus energy in batteries a practical alternative?
To find out, the researchers compared the energetic cost of curtailing solar and wind power, versus the energetic cost of grid-scale storage. Their calculations were based on a formula known as “energy return on investment” – the amount of energy produced by a technology, divided by the amount of energy it takes to build and maintain it.
Using that formula, the researchers found that the amount of energy required to create a solar farm is comparable to the energy used to build each of the five battery technologies. “Using batteries to store solar power during periods of low demand would, therefore, be energetically favorable,” Dale said.
The results were quite different for wind farms. The scientists found that curtailing wind power reduces the energy return on investment by 10 percent. But storing surplus wind-generated electricity in batteries results in even greater reductions – from about 20 percent for lithium-ion batteries to more than 50 percent for lead-acid.
“Ideally, the energetic cost of curtailing a resource should at least equal the amount of energy it cost to store it,” Dale said. “That’s the case for photovoltaics, but for wind farms, the energetic cost of curtailment is much lower than it is for batteries. Therefore, it would actually be more energetically efficient to shut down a wind turbine than to store the surplus electricity it generates.”
He compared it to buying a safe. “You wouldn’t spend a $100 on a safe to store a $10 watch,” he said. “Likewise, it’s not sensible to build energetically expensive batteries for an energetically cheap resource like wind, but it does make sense for photovoltaic systems, which require lots of energy to produce.”
Increasing the cycle life of a battery would be the most effective way to improve its energetic performance, Barnhart added. Conventional lithium-ion batteries last about four years, or 6,000 charge-discharge cycles. Lead-acid batteries only last about 700 cycles. To efficiently store energy on the grid, batteries must endure 10,000 to 18,000 cycles, he said.
“Storing energy consumes energy, and curtailing energy wastes it,” Barnhart said. “In either case, the result is a reduction in the overall energy return on investment.”
Other options
In addition to batteries, the researchers considered other technologies for storing renewable energy, such as pumped hydroelectric storage, which uses surplus electricity to pump water to a reservoir behind a dam. Later, when demand for energy is high, the stored water is released through turbines in the dam to generate electricity.
“Pumped hydro is used in 99 percent of grid storage today, ” Barnhart said. “It works fantastically from an energetic perspective for both wind and solar. Its energy return on investment is 10 times better than conventional batteries. But there are geologic and environmental constraints on where pumped hydro can be deployed.”
Storage is not the only way to improve grid reliability. “Energy that would otherwise be lost during times of excess could be used to pump water for irrigation or to charge a fleet of electric vehicles, for example,” Dale said.
It’s important for society to be energy-smart about implementing new technologies, Barnhart added. “Policymakers and investors need to consider the energetic cost as well as the financial cost of new technologies,” he said. “If economics is the sole focus, then less expensive technologies that require significant amounts of energy for their manufacture, maintenance and replacement might win out – even if they ultimately increase greenhouse gas emissions and negate the long-term benefits of implementing wind and solar power.”
“Our goal is to understand what’s needed to build a scalable low-carbon energy system,” said co-author Sally Benson, the director of GCEP and a professor of energy resources engineering. “Energy return on investment is one of those metrics that sheds light on potential roadblocks. Hopefully this study will provide a performance target to guide future research on grid-scale energy storage.”
Adam Brandt, an assistant professor of energy resources engineering in Stanford’s School of Earth Sciences, also co-authored the study.
This article was written by Mark Shwartz of the Precourt Institute for Energy at Stanford University.
When you plough through all Barnhart’s B.S. there is a simple answer.
It doesn’t work. Period.
“Renewables” need to be stored in the Dustbin of History.
@Bruce of Newcastle at 2:54 pm
No one has mentioned the reason why 4 of the 5 chemical battery systems in the study cannot be used for baseload storage.
There isn’t enough lithium, lead, zinc, bromine and vanadium in the world for that level of usage.
I’m in full agreement. Almost… It has been talked before: A Scott June 30, 2013 at 3:44 pm talked about USGS Lead reserves.
It should be recognized that as demand for a material raises its price and expand efforts to add reserves. But, let’s also recognize that just to store one week’s worth of electricity, we need a thousand times more lead than what is currently in reserves.
Our current reserves of lead converted into national batteries might then run the country for 1/1000 of a week or about 9 minutes.
There is, however, another material that can be mined that will give the nation hundreds of years of stored electricity. — coal.
And Thorium, Uranium (with full reprocessing), hydropower.
Not exactly new ideas, true, but still the best.
It would appear that whenever pumped hydro is considered then the surplus power from (say) a renewable source is used to pump water into an enormous lake, with it’s enormous dam, and so on. Obviously this sort of stuff is not readily available near to centres of population, etc.
Now, consider a diesel power station. This is probably the most efficient energy transfer device known to man (simply because of thermodynamics). In practice we have yer basic diesel engine driving an electrical generator. However, that basic diesel carries it’s own individual turbocharger, it doesn’t share a common giant turbocharger with a whole bunch of other basic diesel sets, that would be absurd. Similarly it will probably have it’s own intercooler sets, a set for each basic diesel. And so on. Individual self-contained units, paralleled up. Unbelievable reliability.
Yet with renewables, we persist in storing our surplus power in mighty lakes and dams.
Unfortunately these are not really compitable with centres of population.
Let us have a renewable plant design based on (say) individual wind turbine sets (compare diesel sets). So each turbine of course, is connected to it’s own generator. Thus for wind power surplus situations, each turbine has an adjacent water column, simply a large water tower, capable of accepting all of the surplus energy output of each turbine as water head and equipped with it’s own dedicated hydro-generator.
I realise of course that diesel sets (which I love) do not over produce by reason of governing and/or selective starting/stopping.
The direct comparison with windturbines would be governors, such that in case of excess power production, the blades would be feathered.
Why don’t they do this?
“””””…… Claim: Let’s put batteries on wind and solar farms
Posted on September 9, 2013 by Anthony Watts
From Stanford University
Stanford scientists calculate the energy required to store wind and solar power on the grid
English: The , also known as the Green Mountain…
Green Mountain Energy Wind Farm, West Texas. (Photo credit: Wikipedia)
Renewable energy holds the promise of reducing carbon dioxide emissions. But there are times when solar and wind farms generate more electricity than is needed by consumers. Storing that surplus energy in batteries for later use seems like an obvious solution, but a new study from Stanford University suggests that might not always be the case…….””””””
Well for 69Cents, and a senior coffee at McDonalds, I could have told him, that !
Seldom, is a solution good for every problem.
Concerning a potential future National Battery Project and resources needed:
I always think back to a Barney Miller episode “Child Stealers” 1980
One of the subplots was a vagrant that told Det. Harris he was really a Columbia Univ. sociologist researcher…. from the year 2057. While the guy was in the holding cell, Harris calls his broker thinking about investing in gold (then at $850/oz before the plunge). Harris catches the guy in cell subtly shaking his head in pity.
Harris hangs up. He talks to the “researcher”. “What’s wrong with investing in gold?”
“I shouldn’t be telling you this, but in a couple of years there will be a huge gold strike in the Yukon. It drove the price right back down to $35/oz. In the Economic turmoil the worlds governments had to find a new base metal for currencies.”
Harris: “So… what did they switch to?”
Guy: “Zinc!”
Harris (puzzled goes back to desk) (dials broker). “I’m back. I’m not sure about gold at these prices. …. Say, what is the current quote on Zinc?
Seventeen and a half CENTS a POUND?!
(glances at guy in cell who is giving a thumbs up). Ok, pick me up a couple of tons.”
Another link to the story: “Climateer Investing”
I have the perfect solution for storage of electricity from wind, and solar PV.
The wind can rotate a huge propeller, so they say; even can be coupled to a generator to make electricity. Well you don’t need the generator; you use the propeller rotation directly to operate a pump; when the wind blows of course.
And you use the wind operated pump to pump oil out of the ground (when the wind blows). When the wind doesn’t blow, it doesn’t pump oil, but when it does, it does.
With the solar PV, you are at a disadvantage, because you have to use the PV electricity to run an electric motor to pump the oil out of the ground (when the sun shines of course).
Well then you pipe the oil to someone who has an electric power station, to provide continuous uninterrupted electricity.
The conclusion of the study … that battery storage makes sense for photovoltaic farms but not for wind farms … is based upon faulty logic. Rather than looking at the cost per kWhr, the study looked only at the energy cost of the generator system vs the cost of the battery storage.
Using the logic of this study, if the capital cost of a generator is low, then it never ever makes sense to couple it with a battery backup. Think about how ridiculous that conclusion is if one it looking at the whole system from the perspective of minimizing either cost or CO2 emissions.
george e. smith says (September 9, 3:50 pm)
I have the perfect solution …
Indeed you do. 😉
The one battery they didn’t compare but should have is Nickel Iron. The will last over 30 years and are the longest life battery out there. The one problem is they waste the most power in the charge part of the cycle. In the early 1900’s they were very common but have fallen out of favor because of size an weight. I don’t think wind and solar power are there yet and may not ever be but Nickel Iron is still used today for off the grid applications mostly with older batteries that are still in service.
Google VRB Technologies of Vancouver, B.C. Vanadium storage batteries, long out of business. Seemed like a good play at the time.
A Japanese tool maker put in a 10-100 for 34,000,000 yen, which you can round to $250,000. It stores 100kWhr of power, delivered at a rate of 10kW. To store one day’s output from a 1,000 MW power plant would require 240,000 of them for a total of $60 billion (with a “B”) dollars. It would be cheaper, by a factor of about 10, to build a spare power plant.
If they made one a tenth the capacity for a tenth the price, it would still be cheaper for me to buy a natural gas-fired 10KW generator and hook it up to my home and spend all the avoided installation cost for the solar or wind power to charge the battery as fuel for the indefinite future.
My personal favourite energy storage is supercapacitor storage.
Say you wanted to store the output of a 1GW renewable facility for 1day – to cover 1GW of grid usage for 24 hours of no wind.
The energy storage requirement is:-
1GW x 1 day
= 1,000,000,000 watts x 86400 seconds
= 86,400,000,000,000 joules or 8.6 x 10^13 joules.
By an interesting coincidence, the amount of energy released by little boy, the nuclear bomb which destroyed Hiroshima, was 6.3 x 10^13 joules. http://en.wikipedia.org/wiki/Little_Boy
So if your 1GW supercapacitor storage facility suffered sudden catastrophic dielectric failure, as highly stressed capacitors sometimes do, or terrorist attack, earthquake, or lightning strike, the resulting energy release would be indistinguishable from a 10 kiloton nuclear explosion.
You would need 100s of supercapacitor storage facilities to stabilise a 100% renewable grid, all of them would have to be located physically fairly close to major cities, to reduce transmission losses.
You know what? I’d rather face a little global warming.
Stephen Rasey says:
September 9, 2013 at 3:17 pm
Another issue, Stephen, is the run-of-mine grade of metal ores have been falling as easily found rich deposits have been exploited. Pricing changes means this isn’t a great barrier to production, since if the price is higher you can afford to mine and process lower grade ores. And increase recycling, although the lead recycling rate is already about 85%.
Unfortunately mining and processing of lower grade ores requires more energy per tonne of metal produced, since you almost always have to crush and grind the rock before you can extract the metals. This would be made worse if large increases in battery metals production were to be required since average head grades would fall even faster.
Here in Australia energy use by mining already is about 10% of the total used in the country, and a lot of that is the trucking and grinding of ore. The energy intensity of mining is getting worse because of the grade effect.
At a certain point as grades decline the energy required to extract the metals required for the batteries will become more than the solar or wind generator can produce in its lifetime. This would be a good study for Stanford team to do, although they probably wouldn’t like the results.
I am aware that bromine and some lithium comes from non-hardrock sources, but the grade vs energy consumption relationship would be much the same. For example the energy and cost of recovering bromine from seawater will be considerably higher than from the rich waters of the Dead Sea, which is the biggest single source of bromine at the moment.
richardscourtney nailed it when he pointed out that there was nothing in the study about economics. It doesn’t matter one bit how much energy it takes to make what. The ONLY thing that matters is the cost effectiveness of the systems with and without batteries. By leaving money out of the equation, they manage to avoid the central issue which is that solar and wind are both uneconomical and if you add batteries to the system, they can only become more uneconomical.
Their safe analogy is equally ludicrous. No, you wouldn’t store a $10 watch (wind power) in a $100 safe. You also wouldn’t store a $200 watch (solar) in a $100 safe if you could get a $10 watch in the first place! And you would purchase neither a $200 solar watch nor a $10 wind watch if you could get a coal or gas watch for 10 cents that didn’t need a $100 safe/battery in the first place.
i read of all these so called scientific studies on all sorts of “what if” situations that all assume we are all going to hell in a CO2 heated global bread basket unless “we do something” and i can never quite get over the utter futility of the logic that drives this sort of inane, so called climate warming science and research.
But most of all the complete ignoring by present science and scientists and the media and blog commentary of the really important items that are fundamental to the survival of the human race. And that is the almost pathological concentration on climate, something that is almost entirely peripheral and inconsequential to our survival as a species.
My reaction is that all this climate BS and crap can only come from so called researchers who like their acolytes have full bellies and all the world’s goods, who have never experienced hunger and who cannot in any way comprehend a world where their local supermarket has rows of shelving and refrigerators almost empty of food items.
[ I saw for myself that rather shocking to a westerner situation of rows of empty supermarket shelves during the last days of the USSR in 1991. ]
One good plant breeder, be it a breeder in any of the world’s basic food grains, is worth a whole truckload or perhaps far more of climate scientists in terms of their importance to mankind.
Sadly in our collective stupidity, the plant breeders and their stupendous achievements in breeding the basic food crops to provide constantly increasing yields and resistance to disease and pests that has led to the ability to feed the world’s ever growing population for near a century now are totally ignored and almost unrecognised in every format and media outlet in the western world..
And yet the climate scientists who together with their so called and mostly heavily biased towards warmist based research, collect vast amounts of publicity, fame, notoriety and some wealth despite being almost completely peripheral and of little consequence to the survival and the quality of the life and of little or no consequence to the survival of billions of people.
Plant breeders and their research and practical application of their research to the plants that feed humanity on the other hand are vital and absolutely fundamental to our ability to adequately feed and to provide a adequate standard of living for the entire human race, all seven billion plus of us.
.
Sadly in our total stupidly, we reward and pay those two groups of researchers, the ultimately inconsequential climate researchers and their vast output of what is just mostly high falutin science sounding and generally useless crap and the fundamental to our survival as humanity, the plant breeders, in completely inverse proportions to their importance to the human race.
In the original batman movie with jack nicholson as joker the evil power company was claiming there was not enough electricity so they needed money to build another plant. But really there was plenty of electricity and they were secretly building a GIANT CAPACITOR!
Using batteries to store energy does seem to be futile and potentially fraught with problems from the availability of raw materials needed to build them and the need to keep them in working order. Not to mention how to dispose of them once they are no longer useable. The US Department of Energy is currently funding experiments into the use of various schemes using battery storage. (Vanadium Redox). It is also funding flywheel technology used to capture energy from wind and solar as a means of storing energy for use when needed. Flywheel technology seems much gentler to the environment than batteries but it doesn’t seem to be talked about. A project in Temecula, California, received $40 Million to start up in 2010 but I can’t find any news, good or bad. You’d think the US DOE would have something to say about it by now?
@Eric Worrall
You know what? I’d rather face a little global warming
That Sir, is a great closing line.
When the cure is worse than the disease.
When we are taking chemotherapy for a cold
When it is 50 times more expensive to stop global warming than adapt to (or welcome) it
When electricity rates must “necessarily skyrocket under” a Progressive’s Plan,
Before we freeze in the dark because the coal mines are closed,
You know what? I’d rather face a little global warming, too.
davidmhoffer says:
September 9, 2013 at 5:42 pm
richardscourtney nailed it when he pointed out that there was nothing in the study about economics. It doesn’t matter one bit how much energy it takes to make what. The ONLY thing that matters is the cost effectiveness of the systems with and without batteries. By leaving money out of the equation, they manage to avoid the central issue which is that solar and wind are both uneconomical and if you add batteries to the system, they can only become more uneconomical….
>>>>>>>>>>>>
No David, I disagree. The first test is whether you use more energy making the darn things and installing them than will be returned over the live of the equipment.
Once that test is passed THEN you look at the $$$$.
Solar, biofuel and wind fail before they get out of the starting gate. They use more energy to manufacture and site than they will generate over their lifetime.
Here in the UK on Channel 4, we have just watched a genuinely frightening play called ‘Blackout’. It showed how quickly slightly annoyed reaction would turn to terror and violence: rioting mobs, theft and murder. With no telephones or mobiles and no petrol pumps operating communications would be at a standstill. Food stolen from unlit stores and no deliveries, leading to panic, housefires and hospitals reduced to batteries as the generators dry up. Then armed soldiers and police deployed (and would we lose democracy at this point?) The helplessness of ordinary people certainly scared me!
So let’s get [fracking] without delay and forget giant batteries.
[Cracking works also. Mod]
I wrote FRACKING but the mobile changed it!
Hope it’s OK this time. In case it writes cracking again that word should begin with an ‘f’.
Philip Bradley says: @ur momisugly September 9, 2013 at 12:46 pm
….Use intermittent solar and wind to pump water up over hills/mountains then harvest the energy used on the other side when electricity is needed. The big advantage of such an approach is that transporting water isn’t time critical, as reservoirs along the way buffer supply to demand for periods of days to months.
>>>>>>>>>>>>>>>>>>
That is the most sensible suggestion but I rather use nuclear power to do the pumping and desalinization.
Its funny how those scientists or researchers trying to fix spilled milk , instead to avoid it in the first place . Can you imagine how much money was wasted in this study alone in wages ? Most people without any academic title know how not to spill milk . Yep , maths are simple , the more wind and solar we build from now on , the more we lose .
@Eric Worrall 5:11 pm – Supercapaciters = Hiroshima
Yes. Any energy storage system contains the danger of releasing it’s energy in uncontrolled ways. Gasoline can catch fire. Gas pipelines can leak. Coal stock piles can combust. We’ve learned hard lessons how to handle these and how to prevent and limit trouble.
Supercapaciter banks, Li-Ion banks, flywheel banks. These hold new types of disasters. All these have the potential for cascading failure, especially in large facilities. Each can release a day’s worth of energy in a few seconds. Immense Power = Energy/Time. Imagine a flywheel breaking free of its mounts imparting its momentum to its housing and neighboring equipment and people.
There might be a Fat Man of electrical energy stored in a supercapaciter bank. There is also the aluminum of the capacitor bank that will burn to add to the inferno. The energy stored in a Li-Ion battery is a fraction of what the battery can release if it burns.
Next to these disasters, I rather adapt to a little global warming. 😉
@ur momisuglyrichardscortney – 10:28 am – economics, not energy return.
@ur momisuglydavidmhoffer 5:42 pm – $10 watch in $100 safe
@ur momisuglyGail Combs 6:32 pm – energy payout
You all have excellent points. What I want to add is the question, “What are you willing to pay for electricity when you do not have it?”
A Boy Scout flash light with batteries is a device that takes far more energy to make than it will ever return. It is outrageous on a $/watt and $/kwr basis. But it is essential equipment because it provides some crucial light when and where you need it.
Why should I buy oil at $100/bbl or gasoline at $3.50/gal when I can get Natrual Gas at $4 / mcf. For one thing, I can carry a gallon of gas, not so the methane. It is a form of energy that can be turned on and off easily, transports safely and lightly, and keeps for months. When connected to a pipeline, nothing better than Nat Gas. When it comes to ease of handling, coal is a pretty useless commodity — except when you work with it in units of 100-ton railroad cars @ur momisugly $30/ton for base load electricity and steam.
I was taken aback by that bit about Cruachan Dam (10:51am) and the need to keep 12 hrs of storage for a “Black Start”, an emergency storage of energy to restart other power stations. Kind of like that Boy Scout Flash Light — it’s not meant to payout, only to save the day if you need it. A little like that flashlight.
Barnhart’s mistake is to consider using battery powered flashlights for everyday lighting instead of for their intended purpose of providing energy when and where you have no other choices.