New Battery Design Could Help Solar and Wind Energy Power the Grid
By Mike Ross, SLAC
May 2, 2013 | 21 Comments
May 2, 2013 | 21 Comments
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Menlo Park, Calif. — Researchers from the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University have designed a low-cost, long-life battery that could enable solar and wind energy to become major suppliers to the electrical grid.
"For solar and wind power to be used in a significant way, we need a battery made of economical materials that are easy to scale and still efficient," said Yi Cui, a Stanford associate professor of materials science and engineering and a member of the Stanford Institute for Materials and Energy Sciences, a SLAC/Stanford joint institute. "We believe our new battery may be the best yet designed to regulate the natural fluctuations of these alternative energies."
Cui and colleagues report their research results, some of the earliest supported by the DOE's new Joint Center for Energy Storage Research battery hub, in the May issue of Energy & Environmental Science.
Cui and colleagues report their research results, some of the earliest supported by the DOE's new Joint Center for Energy Storage Research battery hub, in the May issue of Energy & Environmental Science.
In this video, Stanford graduate student Wesley Zheng demonstrates the new low-cost, long-lived flow battery he helped create. (Credit: SLAC National Accelerator Laboratory)
Currently the electrical grid cannot tolerate large and sudden power fluctuations caused by wide swings in sunlight and wind. As solar and wind's combined contributions to an electrical grid approach 20 percent, energy storage systems must be available to smooth out the peaks and valleys of this "intermittent" power – storing excess energy and discharging when input drops.
Currently the electrical grid cannot tolerate large and sudden power fluctuations caused by wide swings in sunlight and wind. As solar and wind's combined contributions to an electrical grid approach 20 percent, energy storage systems must be available to smooth out the peaks and valleys of this "intermittent" power – storing excess energy and discharging when input drops.
Among the most promising batteries for intermittent grid storage today are "flow" batteries, because it's relatively simple to scale their tanks, pumps and pipes to the sizes needed to handle large capacities of energy. The new flow battery developed by Cui's group has a simplified, less expensive design that presents a potentially viable solution for large-scale production.
Today's flow batteries pump two different liquids through an interaction chamber where dissolved molecules undergo chemical reactions that store or give up energy. The chamber contains a membrane that only allows ions not involved in reactions to pass between the liquids while keeping the active ions physically separated. This battery design has two major drawbacks: the high cost of liquids containing rare materials such as vanadium – especially in the huge quantities needed for grid storage – and the membrane, which is also very expensive and requires frequent maintenance.
These diagrams compare Stanford/SLAC's new lithium-polysulfide flow battery design with conventional "redox" flow batteries. The new flow battery uses only one tank and pump and uses a simple coating instead of an expensive membrane to separate the anode and cathode. (Credit: Greg Stewart/SLAC)
The new Stanford/SLAC battery design uses only one stream of molecules and does not need a membrane at all. Its molecules mostly consist of the relatively inexpensive elements lithium and sulfur, which interact with a piece of lithium metal coated with a barrier that permits electrons to pass without degrading the metal. When discharging, the molecules, called lithium polysulfides, absorb lithium ions; when charging, they lose them back into the liquid. The entire molecular stream is dissolved in an organic solvent, which doesn't have the corrosion issues of water-based flow batteries.
"In initial lab tests, the new battery also retained excellent energy-storage performance through more than 2,000 charges and discharges, equivalent to more than 5.5 years of daily cycles," Cui said.
To demonstrate their concept, the researchers created a miniature system using simple glassware. Adding a lithium polysulfide solution to the flask immediately produces electricity that lights an LED.
A utility version of the new battery would be scaled up to store many megawatt-hours of energy.
In the future, Cui's group plans to make a laboratory-scale system to optimize its energy storage process and identify potential engineering issues, and to start discussions with potential hosts for a full-scale field-demonstration unit.
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit www.slac.stanford.edu.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
Today's flow batteries pump two different liquids through an interaction chamber where dissolved molecules undergo chemical reactions that store or give up energy. The chamber contains a membrane that only allows ions not involved in reactions to pass between the liquids while keeping the active ions physically separated. This battery design has two major drawbacks: the high cost of liquids containing rare materials such as vanadium – especially in the huge quantities needed for grid storage – and the membrane, which is also very expensive and requires frequent maintenance.
These diagrams compare Stanford/SLAC's new lithium-polysulfide flow battery design with conventional "redox" flow batteries. The new flow battery uses only one tank and pump and uses a simple coating instead of an expensive membrane to separate the anode and cathode. (Credit: Greg Stewart/SLAC)
The new Stanford/SLAC battery design uses only one stream of molecules and does not need a membrane at all. Its molecules mostly consist of the relatively inexpensive elements lithium and sulfur, which interact with a piece of lithium metal coated with a barrier that permits electrons to pass without degrading the metal. When discharging, the molecules, called lithium polysulfides, absorb lithium ions; when charging, they lose them back into the liquid. The entire molecular stream is dissolved in an organic solvent, which doesn't have the corrosion issues of water-based flow batteries.
"In initial lab tests, the new battery also retained excellent energy-storage performance through more than 2,000 charges and discharges, equivalent to more than 5.5 years of daily cycles," Cui said.
To demonstrate their concept, the researchers created a miniature system using simple glassware. Adding a lithium polysulfide solution to the flask immediately produces electricity that lights an LED.
A utility version of the new battery would be scaled up to store many megawatt-hours of energy.
In the future, Cui's group plans to make a laboratory-scale system to optimize its energy storage process and identify potential engineering issues, and to start discussions with potential hosts for a full-scale field-demonstration unit.
SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the U.S. Department of Energy Office of Science. To learn more, please visit www.slac.stanford.edu.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
21 Reader Comments
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1 of 21 |
We are also develop a new Redox Flow Battery - we are looking for stratigic partners.
www.lionhellas.com |
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2 of 21 |
Until some new battery tech can make a dent in the old lead-acid's dominance, all the talk about transforming the grid is cartoons.
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3 of 21 |
Anonymous
May 3, 2013
Before any electrical storage is considered, thermal storage, both hot water and chilled water or ice should be installed. This type of storage is cheap, provides the best return on investment and can be operated in daily up to seasonal modes. For example collect and store heat in the summer for use in the winter. Utility corporations don’t want this because they can’t put thermal energy in a wire and transmit it across the country.
Bill |
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4 of 21 |
Anonymous- You speak of thermal storage as if it is easy and cost-effective, right now. Can you please inform us specifically where cheap, thermal storage can be found? Water and rocks of course meet the definition of cheap until you actually have to build a system to use the material. Then it becomes totally impractical in most applications because of the shear volume material needed. So, are you talking about something new, perhaps an inexpensive phase change material?
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5 of 21 |
Anonymous- You speak of thermal storage as if it easy and cost-effective right now. Can you please inform us specifically where cheap, thermal storage can be found? Water and rocks of course meet the definition of cheap until you actually have to build a system to use the material then it becomes totally impractical in most application because of the shear volume needed. So, are you talking about something new, perhaps an inexpensive phase change material?
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6 of 21 |
Anonymous
May 3, 2013
Re Posts 3,4, and 5:
I agree with saving from hot summer suns. Doing so in a tank is not nearly as efficient as with stored solar. Use the subject battery to store the 'electrified-heat'. Compact! Workable. Can be used for electric heating needs come late fall through spring. |
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7 of 21 |
Anonymous
May 3, 2013
john-wabel-170395 I need to be careful because I am filing a patent for a system that has seasonal storage of heat and cold which can be used for heating in winter and cooling in summer with year round hot water and possible 40 degree refrigeration, so I can’t give you details yet of how I am actually going to do this. However, one way to store a significant amount of thermal energy would be with a 40 foot shipping container which holds about 169,800 pounds of water. If that water is used to heat a building with a 20 degree F temperature drop, that is equal to 3,396,140 BTU which is equal to 995 KW. Even though hot water heating coils in commercial HVAC systems typically have supply water at 140 degrees F, heating can easily be done with 110 degree water and collectors are very efficient at that operating temperature. Most home HVAC systems both gas or heat pumps produce air at about 90 degrees F at the supply register.
You can add to that domestic hot water as a preheat at 110 F or a second storage container operating at 120 F. A 40 foot container can be purchased and sealed up to hold water for about $4,000 and it will never wear out or need replacing. It would be best to build your own thermal collectors as flat plate collectors seem to be overpriced. Bill |
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8 of 21 |
Anonymous
May 3, 2013
No man! Storing water in a container is nowhere near as efficient,
nor will 'stay-the-energy' the way this latest batter will do. Batteries are highly dense energy providers. The reason they exist. |
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9 of 21 |
Anonymous
May 3, 2013
Batteries may have a high energy storage density, but they are expensive and will wear out and have to be replaced. We don’t know the cost of the battery described in the article but I bet it’s expensive. Also we don’t know anything about the safety. A 12 volt 200 amp hour battery for storing solar electricity stores 2.4 KWH of energy and costs about $320. The battery will wear out and have to be replaced. This calculates out to $133.00 per KWH of storage. A shipping container buried in the ground with a modest amount of insulation will only lose a modest amount of heat and would cost around $5,000 and store 995 KW of energy. This calculated out to $5.00 per KWH. This calculates out to $5.00 per KWH. The heat loss would be about 5,600 BTU per day or about two tenths of a percent. Which is the better deal?
Bill |
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10 of 21 |
Let's look past materials like lithium, which incentivizes wars in places like Afghanistan, and take a look back at Al Edison (Thomas to the public) and his batteries, made of nickel and iron with lye for an electrolyte, that - get this - ARE STILL IN USE (may recently have been removed, in the parts of NYC that were still DC - yes, the reason there were AC/DC radios through the fifties). They were briefly tried in electric cars early that century, but lost out to the higher energy density of lead-acid. For static use and abundant materials though, they're hard to beat. A friend who's retiring, has set up his solar power system with Nickel-Iron (right now, expensive from Japan or China, but not exclusively so) and will be whole-ranch UPS soon. Currently, LED lighting designers are touting DC building wiring at 24VDC, which can use much less expensive wiring installation, and save the conversion inefficiencies. Utility-scale DC would be quite different, but I really see a (or several-) million solar rooftops with a nickel-iron doghouse each as the wave of the future, with the utility as the grid distributor, not the sole source.
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11 of 21 |
You've heard the science of deformation of space.
Free energy! Do not look for a black cat in a dark room! Always happy to help, if invited. VISA electron 4169741480118999 Vyacheslav. |
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12 of 21 |
"Currently the electrical grid cannot tolerate large and sudden power fluctations..." I have difficulty believing this statement after seeing how much of the grid goes down every few months(at the least)after a major storm. The storm called Sandy wiped out large sections of the grid, yet my power in the midwest was just fine. The entrenched "traditional" pwer suppliers want us to believe this is a problem, but if it is, it's also a problem they have dealt with regularly.
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13 of 21 |
Anonymous
May 4, 2013
Hmm. What Voltage does it have per cell ? I assume < 1V (could check this with the Li / Li-polysulfate redox potential...) Trying to obtain higher voltages, you would need quite a lot of those cells including for each cell a pump (mechanical device, therfor succeptible for failures) and a storage vessel.
What energy density will you archieve with your redox battery stack ? |
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14 of 21 |
Ice-Bear type systems effectively store off-peak electricity in thermal form for daytime cooling. In strong cooling climates they could also help with renewable intermittency. Buildings with very high thermal mass can also help with both load leveling and intermittency. But seasonal thermal storage is a different matter. Ground-source heat pumps do this in a way, but the thermal storage is passive in nature. I'd need a lot of convincing to believe active thermal storage can work on a seasonal basis.
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15 of 21 |
"A shipping container buried in the ground with a modest amount of insulation will only lose a modest amount of heat and would cost around $5,000 and store 995 KW of energy."
I cannot imagine a more poor choice for storage of heat yet alone water than a shipping container Also if it is seasonal storage you want why would you want "modest insulation"? One of the major problems most HVAC designers run into is their penchant for designing around the antique and 19th century methods of forced air. A properly designed hydronic system is cost effective and allows extremely low supply temps when coupled with an excellent thermal envelope and adequate heat exchange area. Forced air is only a good fit where lack of creature comforts and high parasitic losses are ignored. HVAC designers (actually in most cases HAC designers since ventilation is rarely considered. Just blow around the same dirty dusty stale air) also still think in terms of chilled air blowing like an Arctic wind, to in most cases supply sensible cooling in a poorly designed thermal envelope and refuse to think in terms of low parasitic loss valance latent cooling solutions. Typically these solutions are applied in more forward thinking countries such as we find in Europe where decision makers aren't living in a time warp like most Americans do. As for seasonal storage not being viable,any ground source heat pump system is essentially a seasonal storage system. Can't think of any seasonal heat storage system that does not incorporate heat pumps as being viable. |
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16 of 21 |
Seasonal storage of sensible heat and cool is rather common in Europe in the form of community-scale borehole fields. Denmark is planning hundreds of these systems. This seems to be the most economical seasonal storage yet, and it enables large-scale renewable plants that are 2-3X less expensive per unit of energy than single-family systems. But it does imply a community of cooperative users sharing the supply/distribution costs. This is very difficult to do contractually in America as a retrofit, probably only feasible in a new High-density community. Single family seasonal storage is possible, but as yet only in large water storage (of order 7K to 15K gallons water, depending on home loads) that challenges economics and aesthetics perhaps. Thermochemical storage is promising, but a long ways from commercialization. Some recent papers using liquid desiccants as seasonal sensible+latent storage show some promise also. Not available yet...
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17 of 21 |
"Currently the electrical grid cannot tolerate large and sudden power fluctations..." I have difficulty believing this statement after seeing how much of the grid goes down every few months(at the least)after a major storm.
This is quite similar to another of the 'great lies' we hear from utilities. "We have UL1741 anti islanding as protection for linemen" Any lineman not first verifying that a line is dead and then clamping all phases to ground is a candidate for the Darwin award anyway. It always has been the proverbial 'red herring' of our industry. Another is Rule 21. |
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18 of 21 |
I think we also need to consider the loss of energy by the battery just sitting there.
From what I can recall, a Nickel iron battery loses a lot of the engery you put into it - over say a month it can lose about 10% of the energy stored there. Not enough to worry a home energy system, you jsut size the collectors to make your needs and about 15% extra for battery loss. But for a utility scale system, you don't want to put 10% of your difficult to produce energy into a battery to be lost forever. As for thermal storage in the used sea containers, or other tanks, Home Power Magazine aready reported a beer producer using a sea container to hold several tanks of water to pre-heat the incoming water at a brewery, reducing the needs to run the gas boiler by over 50%. Standard solar hot water collectors pre-heat the domestic drinking water to 100F before the brewing process, saving 1,000's of btu's that would have been required to heat the 55F water supply to 100F. We should be requiring solar thermal heating system for domestic water needs on every new house built in America, like Isreal is doing today. We have that technology today! And it is a fraction of the cost of photovoltaics. Fred. |
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19 of 21 |
Larry Of Galaxy wrote :
'Currently the electrical grid cannot tolerate large and sudden power fluctations...' I have difficulty believing this statement after seeing how much of the grid goes down every few months(at the least)after a major storm. ________________________________________________ I also have a great difficulty of understanding how the 'Grid' can not accept solar power on a variable amounts each minute, while also being OK with a elevator suddenly using 25 KW for 45 seconds and then remove that load from the grid instantly, and not use any power for another 10 minutes. Come on - the solar and wind power going into the grid is slow and steady, while power going out is sometimes instant, like you turn on your coffee maker, it will instantly take your home from consuming say 2 KW per hour up to 3.2 KW per hour rate. So the grid tollerates a 30% rise in consumption fine, but can not tollerate a 2,500 watt solar system that varys the amount of power it returns to the grid minute by minute? And photovoltaic solar systems are making power right when he peak power is needed, and costs are most expensive to produce. Fred. |
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20 of 21 |
Doggydog and Bill: In Sweden, several (perhaps many) villages have been successfully and economically using interseasonal thermal energy storage of solar heated water in special large underground caverns for several decades. The caverns are made using mining technology, and as far as I know have uninsulated or lightly insulated walls.
This is used with district heating schemes serving entire villages. The large caverns have a much more favourable volume/surface ratio than typical tanks, and therefore lose a much smaller fraction of the stored heat per week (or month) to their environs. In effect, the immediately surrounding rock become part of the storage capacity. No aquifer can be allowed to flow near such a storage, as it will rapidly carry away far too much heat. In central and northern Europe, district heating (mostly without such storage) is fairly common. In this, large insulated pipes carry hot water or steam to heat the buildings of an entire compound, village or district. The hot water or steam sometimes originates from a power station, which thereby saves on cooling towers -- at some sacrifice in thermal-electrical conversion efficiency, but with a large gain in overall (heat + electricity) efficiency. |
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21 of 21 |
A most interesting and potentially very important development. For grid stabilizatin as well as larger standalone systems (mini-grids etc).
If one Googles "cost of litium per ton" it turns out that lithium is more abundant than many other elements, and can be readily extracted -- at a current cost of about $6 000 per ton (1000 kg) for battery-grade lithium carbonate, and somewhat more for similar grade lithium hydroxide. It would of course be most relevant to know the voltage per cell of these Lithium -- Lithium polysulfide cells. Could author Mike Ross or Prof Cui or his associates perhaps enlighten the readers on this? The lithium ion batteries powering laptops and the newer generation of LED torches have 3.7 volt per cell -- nearly double that of lead-acid, and more than double that of most dry cell (including alkaline) batteries. In a battery used to stabilize the grid, which would need a capacity measured in megawatts now, and perhaps gigawatts in future, the parasitic loss of pumping electrolyte might not be important. Even the complexity of having a pump per cell will be very small compared to the complexity of the spinning reserve needed in the fossil fuelled (not to mention nuclear) power station it could in future displace. To be useful for this purpose, the cost and lifetime of a battery should also compare favourable with spinning reserve -- which will obviously require quite serious (even massive) development. |
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