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.
Grey Lensman:
I am at a loss to understand why your post at September 10, 2013 at 4:16 am is addressed to me when it concludes
I have repeatedly argued that same ;point in this thread; e.g. at September 10, 2013 at 2:48 am I wrote to you saying in total
However, your post I am answering says
Yes, and the over-use of windpower is responsible for that.
Pumped Storage is useful because it avoids the need for a few power stations to operate all the time so they are available to provide power in the short periods when there is peek demand. Pumped storage is expensive and cannot provide power for very long (this inability to provide power for several days is why pumped storage is not a useful back-up to windpower). But pumped storage is cheaper than continuously operating power stations to supply for the short periods of peek demand.
Windfarms require so much back-up that there is no need for the pumped storage: the additional back-up (plus safety factor) for the windfarms is available. And this back-up is but one of the reasons why windfarms are so expensive an addition to electricity grid supply.
Richard
Mike Hohmann:
At September 10, 2013 at 3:41 am you ask
No, it is too stupid for words.
Please read this thread and note the comments (from several commentators) which state both the technical difficulties and the hazards of storing hydrogen. Hydrogen storage is almost as dangerous as large energy storage using flywheels.
Richard
Richard, It was not my suggestion, it was a concept that I put out there to demonstrate the logical fallacy of batteries. That is why i replied. Also to point out that I agree with you and others re what we should be doing. Not keen on nuclear but well done, it has a strong case. I admit no science, no facts, no data, i just dont trust nuclear.
The Dinorwig Pump Storage in Wales, cost so much and used I believe, amongst many other things, one million tonnes of concrete. I am certain, again gut feeling, that greens have little between the ears.
Is storing browns gas better than hydrogen. Even can it be done?
There are now several, well thought out and documented papers, that tell the truth about Wind and Solar, plus the Spanish Green energy managers book saying the same but from actual operational experience, they are not sustainable. How to get that message, out and understood, thats a real problem.
Stephen Rasey says: @ur momisugly September 9, 2013 at 8:00 pm
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?”
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Stephen, I have zero problem with wind and solar and biofuel = “Gobar Gas” in niche markets. Heck I use a solar powered fence charger in areas where it is difficult to run commercial electricity. Windmills were often used to pump water for live stock in the USA but have now been replaced with diesel generators.
Where I have a problem is MANDATING western civilization be run using power generation that has a negative return on energy invested. Are we going to use school kids on treadmills to generate the electric to make the solar panels and windmills to supply the elite with power?
Our civilization is based on cheap readily available power. 82% of Americans are in non rural areas per the last census. Take away electricity for several days (no refrigeration, no stores open…) and you are looking at massive riots especially if the cause is rotten governance instead nature causes.
I read somewhere that all the batteries on earth could store global electricity demand for ten minutes…
Bit simplistic, but if true it gives a feeling for the scale of the challenge..!
nc says:
September 9, 2013 at 11:02 pm
Is there no thought given to the poor Power System Dispatcher that would have to manage all these pipe dreams…..
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Oh we hear you. The key words being Unreliable and intermittent.
Only bureaucrats and ivory tower idiots with no real world experience could have dreamed up this massive idiocy and then think a SMART Grid and constantly shutting down power to consumers is the answer.
I worked in a chemical plant where if the lights flickered everyone from the plant manager down headed for their emergency stations at a dead run so we could shut down the continuous process in an orderly fashion. I also worked for another company that ran steel foundries making aircraft parts. Again constant power is an absolute must. Too bad our bureaucrats and academics don’t have similar experiences under their belts.
it is all nice and free with O.P.M
***
Stephen Rasey says:
September 9, 2013 at 8:00 pm
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.
***
In the utility I worked for, a black-start would be initiated by a relatively nearby once-thru (not pumped-storage) ~60 MW hydro-plant. Once our coal power plant got started, it could power other plant restarts further away. The pumped-storage hydro-plant on our system never came into consideration for a “black-start”.
@ur momisugly Chris y, it appears you performed a linear scale-up to obtain the $110 million figure. The cost would be far less, due to economies of scale.
We use an exponent of 0.6 to estimate costs of larger systems. Therefore, a system 9 times larger would cost 9 ^0.6 = 3.7 times the base cost. Just roughing the numbers, and assuming the base cost is correct, the $110 million should be about $45 million.
That is still prohibitively expensive.
richardscourtney says: @ur momisugly September 10, 2013 at 2:37 am
Gail Combs: I rarely disagree with one of your usually very fine posts, but this is one of those rare occasions….
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We are coming at this from two different directions. As Stephen Rasey indicated Wind, Solar, Batteries, “Gobar Gas” are fine at filling niche markets and I have zero problem with that. However there is no way on God’s little green earth that you can run an entire modern civilization on energy that costs more in energy to produce than it delivers. PERIOD
Unfortunately that is the current plan so that is the point of view I am coming from. It is the only reasonable way to look at the current political situation. Will Wind and Solar and Biofuel provide the energy for modern civilization? The answer is NO, not because of the $$$ but because of the underlying problem of energy expended vs energy return. All life runs on that principle. Break that rule and you eventually end up dead.
My usual backup data:
Poland put on the breaks:
Nuclear and hydro are the only non CO2 producing energy sources that would do the trick of reducing CO2 emissions AND allow a reasonable level of civilization. However these are two energy sources that are vehemently opposed by the GREENIES so we are left with Wind Solar and Biofuel.
Mike Hohmann says:
September 10, 2013 at 3:41 am
OK, pumped storage of surplus energy is ‘good’, but not ubiquitously possible. But splitting water and storing the hydrogen is. Too obvious for words?
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No too darn dangerous! Storage of hydorgen is a (self-snip) nightmare. Take it from a chemist who wrestled with hydrogen tank leaks for years and had a tank blow through a cement wall.
The molecule is so small it leaks through just about anything with a junction. And that is before you deal with Hydrogen Embrittlement of Metals
Gail, thanks for your hydrogen info input. it seems then that any hydrogen solution, is fatally flawed and that includes hydrogen solids, that require low heating to gas. The resultant gas destroys any pipework, devices after generation.
I really cannot believe the sample quoted. The cost of a 1mw battery triples the capital cost, maybe more, of the generating plant, all to reduce nox slightly??. I just cannot believe how they get away with it.
The worlds most powerful electric car, 1,000 hp plus, claims a range of 250 miles, yet only has a massive heavy 92 KW/Hr battery. How does that work?
Richard, sorry for the misunderstanding, at my little place, I am used to being “implicit” rather than “explicit” to cater for my readers less academic qualification. nevertheless, they are still thinkers and I am used to getting them to think, hopefully.
Somehow, we need to get a paper out, with full fanfare and global reach that nails the wind/solar myth once and for all. My readers are still locked into “wind is free how can it be unsustainable”. They just cannot believe it, so strong is the meme. When I direct them here, all I get is “OH, wattsupwith that a very questionable place” lol
@ur momisugly Gail Combs, and energy systems that consume more than they deliver.
Actually, our modern electrical grids do exactly that. We consume 2.5 to 3 times as much energy as is delivered to the customers.
A modern grid in the US has approximately 45 percent thermal efficiency for the generating plants, with a mix of nuclear at about 33, coal at about 40, and natural gas power plants at up to 60 percent. Allowing for losses in transmission and transforming up and down in voltage, the system easily consumes the above numbers, 2.5 to 3 times the delivered power.
It becomes much worse for certain systems, such as a simple cycle gas turbine peaking power plant. Such a plant has low efficiency and can consume 5 times as much energy per unit of energy delivered. We don’t care, because we need that peaking power to stabilize the grid on high-load days.
The prime consideration is economics.
Grey Lensman:
Thankyou for both your comments addressed to me in your post at September 10, 2013 at 7:50 am
http://wattsupwiththat.com/2013/09/09/claim-lets-put-batteries-on-wind-and-solar-farms/#comment-1413294
I write to answer this one
Perhaps it would help to point out the following.
All energy is free. It was all created at the Big Bang. But it is costly to collect energy and to concentrate it for conduct of useful work.
Fortunately, nature has collected and concentrated energy for us.
For example, the little energy available in sunlight has been collected by photosynthesis over geological ages, and the collected energy exists in dry, compressed stores known as fossil fuels.
The energy available in sunlight as it falls, or the solar energy collected as biomass is in such small amounts that collecting it costs much more than collecting the energy concentrated in fossil fuels.
Wind is also energy supplied by the sun but it is also too feeble in normal winds to make its collection affordable when the solar energy collected by fossil fuels is so much and is so concentrated.
However, hydropower is solar energy collected by evapouration over large areas which is concentrated when it falls as rain and is routed to rivers by geography. This large collection area makes hydropower affordable in competition with fossil fuels and nuclear power. (Nuclear power is energy concentrated by now long-dead stars).
The high concentration of energy in fossil fuels is why windpower and muscle power (from animals and slaves) were abandoned when the high energy intensity in fossil fuels became available for use as power by using of the steam engine.
But hydropower was not abandoned and is still used because the energy intensity in falling water is comparable to the energy intensity in fossil fuels.
In summation, collecting energy for use is cheap by using hydropower, fossil fuels and nuclear power because nature has done most of the collecting. But collecting energy is expensive from wind and solar because we have to do all the collection ourselves.
Richard
@Grey Lensman at 7:50 am
And we are PROUD of it.
We question everyone and everything.
Thank you Richard an excellent summation. Indeed the worlds very first hydroelectric plant is still in operation.
“In 1868, a hydraulic engine was installed, with water being used to power labour-saving machines such as laundry equipment, a rotisserie and a hydraulic lift. In 1870, water from one of the estate’s lakes was used to drive a Siemens dynamo in what was the world’s first hydroelectric power station. The resultant electricity was used to power an arc lamp installed in the Gallery in 1878. The arc lamp was replaced in 1880 by Joseph Swan’s incandescent lamps in what Swan considered ‘the first proper installation’ of electric lighting.
The generators, which also provided power for the farm buildings on the estate, were constantly extended and improved to match the increasing electrical demand in the house.
http://en.wikipedia.org/wiki/Cragside”
It is also a place of beauty and wildlife. Also see Willis report re English Canals, industrial behemoth converted to environmental havens and beauty spots. Sad the greens just cannot see themselves in the mirror.
Grey Lensman says: @ur momisugly September 10, 2013 at 7:50 am
….Somehow, we need to get a paper out, with full fanfare and global reach that nails the wind/solar myth once and for all. My readers are still locked into “wind is free how can it be unsustainable”. They just cannot believe it, so strong is the meme. When I direct them here, all I get is “OH, wattsupwith that a very questionable place” lol
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Check out Charles S. Opalek, PE book WIND POWER FRAUD
Also THE DARK SIDE OF “GREEN”: WIND TURBINE ACCIDENTS, INJURIES AND FATALITIES RAISE SERIOUS SAFETY CONCERNS
For a response to “OH, wattsupwith that a very questionable place”
use Amelia Sharmanab, Mapping the climate sceptical blogosphere paper where she says
There is also my count of over 100 people with degrees in math, science and engineering here at WUWT. This means the conversation may get a bit technical but there is usually someone available to explain matters to a newbie.
Roger Sowell says:
September 10, 2013 at 8:09 am
@ur momisugly Gail Combs, and energy systems that consume more than they deliver.
Actually, our modern electrical grids do exactly that. We consume 2.5 to 3 times as much energy as is delivered to the customers…..
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You missed the entire meaning Roger.
The amount of energy produced by a wind turbine during its ENTIRE WORKING LIFE is LESS than the amount of energy needed to mine the ore, process it, manufacture the parts, fabricate the turbine transport it and set it up. Wind turbines are a dead loss! They are an energy BLACK HOLE! Heck you have to use grid energy to turn them during days of no wind so they do not deform or seize up.
That is why Charles S. Opalek, PE says WIND POWER FRAUD: WHY WIND WON’T WORK
Wind power is nothing but a massive wealth transfer mechanism that is sucking money out of the pockets of the poor and placing it in the pockets of the rich. In the UK it is even taking the lives of the poor as they can not afford to eat and stay warm.
It always amazes me that as soon as “batteries” are mentioned, the environmental impact of manufacturing those batteries are never included in the equation. The mining process produces all kinds of toxic runoff. The shipping and refining of the ore, the actual manufacturing of the battery, the shipping of the battery to it’s needed location and eventually the disposal of the battery use all kinds of energy, most of it from non-renewable energy sources. I’m sure the manufacturing of the battery offsets any benefits the storage of “renewable” energy when it comes to the impact on the environment.
RE: Roger Sowell at 8:31 pm
This is not for wind or solar power storage, but to reduce pollutants into the air from the diesel-powered generators on the island. …. The diesel generators now run at a nearly constant rate, with excess power stored in the batteries at night.
This is what I do not understand about the design and operation of hybrid cars. Are there any models where the gasoline engine runs at a constant speed and is not connected to the drive train?
Back in the late 70’s early 80’s I remember a Scientific American article on a flywheel storage hybrid car. (To their credit, they included a photo of the damage a failed flywheel can cause!) The point I remembered from that was it takes only 50 hp to maintain freeway speeds and replace the energy drain from air resistance and rolling friction. Accordingly, these authors maintained that you install a small gasoline engine, run it at its most energy efficient and environmentally clean constant speed to top off the energy storage bank, either batteries or flywheels. The bank itself doesn’t store much energy, only enough for a few miles. What the bank does is provide the power to accelerate and using regenerative braking. I thought at the time it made sense. Flywheels had the advantage of being able to take high power rates for charge and discharde. Flywheels had a bunch of disadvantages, especially in a moving, tilting, bumpy device and that is only some of the reasons we haven’t seen them.
But the concept of a constant running gasoline engine + battery bank for variable power seemed solid.
Yet today, I see a top hybrid 2012 Toyta Prius C: 1.5 L, 4 cyl, Automatic (variable gear ratios). Gear ratios? The gasoline engine has a direct connation to the drive train? 1.5 Liter? That’s not the small, constantly running engine of my youthful imagination.
What the heck is wrong with the continuously running electrical generator, no transmission, totally electrical powered and regenerative drive train concept? Why doesn’t it win on cost from simplicity alone? Is it a human cognitive disconnect of an engine that doesn’t run faster as you accelerate? Is there a more fundamental engineering problem?
The proposed tidal barrage across the Severn Estuary in the UK looks promising as as it would generate the equivalent of 3 modern nuclear or 8 large coal-fired power stations during tidal max. Boats get in and out via a system of locks but migratory fish eg salmon can’t. The risk of flooding, seaward side is increased.
It would divert funds away from unreliable wind power as it would cost £40 billion. The one in La Rance, France has been running for 40 years without major mechanical problems. The warmist WWF, RSPB and Friends of the Earth are against it as they prefer wind farms.
Stephen Rasey says: @ur momisugly September 10, 2013 at 9:30 am
…..What the heck is wrong with the continuously running electrical generator, no transmission, totally electrical powered and regenerative drive train concept? Why doesn’t it win on cost from simplicity alone? Is it a human cognitive disconnect of an engine that doesn’t run faster as you accelerate? Is there a more fundamental engineering problem?
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Possibly too simple, too easy to fix and would last too long. Corporations are not interested in the best engineering only in the engineering needed to sell the product and get repeat customers. Emphasis on repeat customers. Why else don’t we have cars that are powder coated and would last for 25 years without rusting out?
As King Gillette said. “Give them the razors and sell them the blades”
Also do not forget interconnecting board members between corporations not to mention banks.
paulinuk:
re your post at September 10, 2013 at 9:34 am
I am opposed to a tidal barrage but very strongly supportive of tidal coffer dams in the Severn Estuary.
You can read my reasoning here
http://scienceandpublicpolicy.org/images/stories/papers/reprint/courtney_2006_lecture.pdf
Richard
paulinuk says: @ur momisugly September 10, 2013 at 9:34 am
The proposed tidal barrage across the Severn Estuary in the UK looks promising…
The warmist WWF, RSPB and Friends of the Earth are against it as they prefer wind farms.
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Check out who actually funds and therefore controls WWF, RSPB and Friends of the Earth. You can start here: http://nofrakkingconsensus.com/category/money-funding/
@ur momisugly Gail Combs, re missing the point.
I fully understand the point of using more energy to manufacture a device than the device will produce. My point is, we do not care.
Economics is what matters.
All energy systems have losses. That means that always, always, always, more energy goes in than goes out.
As to energy used in manufacturing a device, again nobody cares. If we can build a device by using huge amounts of cheap energy, then the device delivers energy when and where it is needed, we charge enough money for the product energy and walk away happy.
I have not run the numbers, but I suspect that a prime example is a diesel-powered emergency generator. The energy required to mine the metals, refine the metal, shape the machine, and transport it to its destination is likely far more than the energy delivered by its infrequent use.
So, why do we allow emergency generator systems? We can ask the patients in a hospital. Patients would die during a power outage, if not for the emergency generators.
Energy required to build a system is not the issue. Economics is the issue.