Conventional battery: Ordinary batteries use at least one solid active material. In the lead-acid battery shown here, the electrodes are solid plates immersed in a liquid electrolyte. Solid materials limit the conductivity of batteries and therefore the amount of current that can flow through them. They’re also vulnerable to cracking, disintegrating, and otherwise degrading over time, which reduces their useful lifetimes.
Arthur Mount
Donald Sadoway conceived of a novel battery that could allow cities to run on solar power at night.
Without a good way to store electricity on a large scale, solar power is useless at night. One promising storage option is a new kind of battery made with all-liquid active materials. Prototypes suggest that these liquid batteries will cost less than a third as much as today's best batteries and could last significantly longer.
The battery is unlike any other. The electrodes are molten metals, and the electrolyte that conducts current between them is a molten salt. This results in an unusually resilient device that can quickly absorb large amounts of electricity. The electrodes can operate at electrical currents "tens of times higher than any [battery] that's ever been measured," says Donald Sadoway, a materials chemistry professor at MIT and one of the battery's inventors. What's more, the materials are cheap, and the design allows for simple manufacturing.
The first prototype consists of a container surrounded by insulating material. The researchers add molten raw materials: antimony on the bottom, an electrolyte such as sodium sulfide in the middle, and magnesium at the top. Since each material has a different density, they naturally remain in distinct layers, which simplifies manufacturing. The container doubles as a current collector, delivering electrons from a power supply, such as solar panels, or carrying them away to the electrical grid to supply electricity to homes and businesses.
The key is a modular design, which could make the technology practical as a way to keep the grid stable and reduce electricity costs.
Digital quantum batteries could exceed lithium-ion performance by orders of magnitude.
While the article doesn't state requirements in terms of volumes, it does say that for NYC a 13 GWatt requirement "would fill nearly 60,000 square meters."
Doing a quick back-of-the-envelope calculation, this works out to a little more than a city block of area (660ft x 660ft). How much of that could be stacked and built underground is not known, but depending on how much room you need for interfacing the system to the power grid, buildings and parking for workers, security spaces around the facility, etc., for a 4 square-city-block area this would be about 37% of the available space.
The real driver on renewable power based on wind and photovoltaic systems (after technical feasibility) are the costs of storing a kwh of power, the efficiency of the charge discharge cycle, and the life of critical components. Typically a storage system is only going to go through one or two charge discharge cycles per day. So if the system costs $100 per kwh of storage capability and is 99% efficient kwh in to kwh out(not likely), it costs $1200 to $2400 per daily kwh to run as part of a system. A simple cycle gas turbine system even with fairly expensive gas will be a cheaper way to go for peak needs. It is clear that storage and dispatch capability is the key to a functioning wind or photovoltaic system. We can only hope that this effort will bring a new set of possibilities.
"storage" is not the problem that you describe
The big problem with the electric power grid is producing power when you have little demand. A smaller problem is power produced intermittently.
Roughly two thirds of our power comes from coal and nuclear power plants. Because it takes days to heat them up or cool them down, they are never turned off, except for problems or some types of maintenance. These are called base-load plants.
This means they produce lots of energy in the middle of the night when demand is quite low. The incremental cost of power during peak periods is usually at least an order of magnitude greater than during the least used off peak periods. If your first sentence was correct, we would have none of these plants now.
How does the grid handle this problem now?
First, lower prices for using off peak power induce large industrial customers to shift their use to the middle of the night. We should be doing more of this, including many more commercial and residential customers, as time-of-day meters become less expensive. An important new use would be plug-in hybrid vehicles.
Second, natural gas power plants can be turned from off to full capacity, or the reverse, fairly quickly. They have relatively low fixed costs but relatively high incremental costs. They are called peaking plants.
Third, hydro is used extensively in reverse. Pump water above the dam so more power can be produced during the day. Because of long-distance transmission, this is used for large areas of the country. It's quite efficient.
The same three approaches would be used for wind or solar. Neither could be relied upon for providing peak power, though when available they would substitute for more expensive natural gas power.
The intermittent nature of their power introduces no big problem for the grid either. The power from a portfolio of wind or solar facilities would vary significantly, but it would almost always be slow enough for a natural gas plant to compensate for changes.
If the level of power changes very quickly now, power is quickly brought in from a longer distance or heavy industrial customers that have already agreed have some heavy power uses quickly cut off. The grid has a reserve capacity to adjust to such situations and assure reliability. This would continue.
All of the problems you discuss, we deal with now. Batteries, supercapacitors, peak/off-peak pricing, long-distance DC transmission, and thermal storage should all play a larger role in addressing this problem. They are each quite important, especially if there are any cost breakthroughs—but big changes in these technologies are not essential to absorb large amounts of wind and solar into the grid.
Re: "storage" is not the problem that you describe
Interesting. Has the Mazur MagLev wind turbine been considered with this type of battery storage?
A pod of these turbines with the batteries withing a circle of 2G turbines could enable the states with a lot of wind to contribute mightily.
With liquids sloshing around in giant batteries, what is the likelihood that in an earthquake the metallic electrodes might be shorted out? Could this lead to an explosion? How does a liquid battery respond in such situations? With the "huge" batteries envisaged, safety is also a huge issue. Small individual cells might fare better, and the liquids might need to be stabilized in some kind of porous inert solid to prevent such accidents.
In addition, magnesium is highly reactive and accidental exposure of hot molten magnesium to air, as might happen if the battery is damaged by an earthquake, could result in an extremely dangerous fire.
Plenty of industries--including the current power industry--safely maintain plants that are full of horrible, dangerous, toxic, flammable materials.
I think the use of this device would be better suited to a Distributed power system. The Grid system is an extremely vulnerable and inefficient system, costly to implement and, to a lesser extent, environmentally unfriendly. The use of hydrogen reformers on a fuel cell utilizing natural gas supplemented by solar or wind would boost the efficiency of the system, eliminating line losses and unnecessary infrastructure.
How are these different than Flow Cells?
What are the main differences between this liquid battery and a flow cell device? The Regenesys system sounds more like a large liquid filled tank of electrolytic materials which gets changed out periodcally by flushing the old solution and filling the container back up again. These liquid battery systems look like the fluid flows in continually through some type of filler passage. Correct?
What are the practical sizes that either can be made? If we're to look at electrcial vehicles as our primary mode of transportation in the future we'll all need power systems at home capable of storing inexpensive power at night so we can charge our cars up for travel.
Besides, distributing emergency power house by house removes and SPOF in the power grid from a consumer perspective. A 10 to 20KVA system for home emergency power may be pretty cheap to produce, and low enough to pay for with a HELOC.
Re: How are these different than Flow Cells?
No, in the liquid batteries, the liquid does not flow through.
From a table, that didn't make it into the article, comparing the liquid battery to several other battery technologies:
Flow Battery; Uses liquid active materials, but requires about 5 times more space than the MIT battery because it uses dilute electrolytes. Lifetime uncertain, possibly as short as a few years. (It's also more expensive.)
Re: How are these different than Flow Cells?
But it is basically a very slightly modified Zebra battery (change Ni for Sb, NaAlCl4 for NaS and Na for Mg and you have the original Zebra battery).
Why not available in a year
So the next step is to adapt this storage technology into a Gel, then retrofit the gasoline storage tanks at petrol stations to hold this gel. Then electric cars could easily get a recharge by pumping out the spent gel and pumping in the charged gel. The stations could charge from the grid any time the price was right...
How can I help make this happen?
_Vaughn Micciche
Re: Retrofit Petrol Stations --
I think you may be onto something. i mean that could be a brilliant solution for recharging the batteries of an electric vehicle, i really dont think it matters if its a gel or a liquid but you could hold the spent fluid in a seperate tank and as you pump out spent electrolyte you pump in fresh electrolyte, its genius. of course you need cars that can do this and stations equipped with the new pumps but i dont see why it wouldnt be feasiable.
Re: Retrofit Petrol Stations --
Interesting idea, however, you would be unable to retrofit an existing gasoline station. The economies of scale would prohibit this anytime in this Century. Many of our problems are not in the technology we devise, but the ability to implement and make practical from a cost and safety perspective. Especially the safety aspect.
Re: Retrofit Petrol Stations --
While your gel idea is nice, it really doesn't work with these batteries. The liquids in these batteries are molten metals. It's not a viable option for a car. They have to be kept extremely hot at all times. They need to be really big with lots of thick insulation to minimize heat loss (and thereby minimize the cost of continuously heating them).
VBR flow batteris and car batteries.
I did some reading and compared to the flow batteries I read up on (VBR). This baterry does need a membrane buts uses a salt instead. A pump is not needed with this battery, instead gravity is used. So it is mechanically simple and could have lower maintence cost.
As for using it as a car battery VBR have already been tested in electric golf cart style along with refueling by putting changed battery liquid in . The problem seems to be weight. What is the power density/kg? VBR did not match solid batteries. Also the mechanical simplicity would probably not work in a moving vehical, flow battery might be better in case where the liquid will be moved around, and not sit still.
This would be great on trains, to regenerate braking energy and turn locomotives into large hybrids!
Most locomotives are diesel-electric and could easily put electricity into batteries when breaking instead of burning off electricity via a heating coil.
The liquid battery could be put into three or four liquid containers behind the locomotives, and when the train brake the electrical motor generate energy lowing the train and charging the batteries. Moving forward the train would suck current from the batteries.
If they can get it to a couple million (10million) per unit, it would sell, because of the return on investment and aid in lowering fuel costs!
http://science.howstuffworks.com/diesel-locomotive4.htm
Brian Glassman
Commercialization
Innovation
Aside from the obvious day/night storage problem, there's also the seconds-to-minutes variability of wind and (to a lesser degree) solar output, which causes dispatch and stability problems for the grid.
Being electrochemical, batteries (these, or any others sufficiently cheap) should be capable of sub-second changes in power flow and direction, AND -- unlike supercapacitors -- store enough energy to address the day/night problem as well.
They would seemingly be co-located remotely, at the wind or solar farm, so peak power levels don't have to be sent far and transmission lines from farm to city can be steadily (and efficiently) loaded. Not to mention the safety aspects of keeping gigajoules of stored energy away from populated areas. (With apologies to any country folks here).
The temperature of the material stacks is very important when applied at the small / distributed scale. Does self-resistance heating keep it warm? Too warm? What happens when the stack cools? And how best to warm it up again?
These Liquid Batteries sound very promising. Are there any smaller scale liquid batteries out there for the public yet?
Does Voltage matters to this storage?
Does this form of electricity storage have limit to the input voltage? By think it from top of my understanding, it seems like as far as the input voltage is a little bit higher than what the liquid battery voltage is, the charging will happen.
My next question is what is the input current limitation. It seams like as far as the battery still have room for charging, there should not have current limitation given the probe and connectors touch the liquid is not the bottleneck.
Please, some one confirm with me on these points?
If above understandings are true, then, a control circuit will have very loss requirement in terms of controlling the input voltage and the current. That will give wind turbine out put big relieve.
Thanks,
Jch99233
Correct me if I am wrong but hasn't this concept already been proven at: Gemasolar solar plant in Seville, Spain
http://www.technologyreview.com/energy/37756/page2/#photo
They are using solar reflector to heat molten salt to 900C, which will then be able to produce energy during the day and night
One thing i would like to know for this new battery, is how is the salt being heated to a liquid state. Especially if it is at the back end of a wind mill
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lasertekk
146 Comments
How big?
A stated volume would be more useful in describing the needed battery size.
Reply
TestPilot
13 Comments
Re: How big?
Size not really an issue here. Cylinder 10 meter high, 20 meter radius would hold many thousand tons of liquid metals. Capital cost of investing into battery itself is an issue.
Lets count.
3 times cheaper then small scale batteries. That mean capital cost of storing kwh in proposed battery would be $40 or even less. Thermal losses are less then 5%, probably as low as 1%.
One charge/discharge cycle per day. Utilities will buy electricity at four to five cents per kwh, in a peak hours, and they still be happy to dump excessive electricity during hours of low demand.
Annual income $15 to $20(per kwh capacity). Large scale operational costs probably be in a range of couple dollars annually.
Add ROI, and we are looking 3 to 5 years(5 years is a worst case scenario) till investors get profit.
Major questions - will this battery last 5 years, being daily charged/discharged? Is it really 3 times cheaper per kwh then most competing designs? What is a response time - counting from moment utility decided it need extra power, till pouring megawatts into the grid? Those could affect profitability drastically.
And, BTW, load balancing is already multi-hundred-million dollar business in US alone.
Reply
Guest (Bob61984)
Battery life...
I'm off the grid and use lowest tech "golf cart" lead acid batteries. Life expectancy for golf cart batteries is 4-6 years. My first set lasted 8 years, but was noticeably in need of replacement during the last.
L-16s which are also used in off the grid applications can last several years longer.
I suspect these batteries would be something more in the 3x5 lifetime range rather than only 5 years.
---
BTW, the article talks about storing solar "all night long". That's not what the grid is going to need. We will need to shift some solar produced electricity from day to evening hours. Peak use hours extend until the time that people start going to bed. After that we are likely to have all the power we need from wind farms and other sources.
And these batteries can help smooth input from wind farms so that more than 35% of their produced power can serve as baseload power. (That's "produced", not "nameplate".)
Reply
nick47g
18 Comments
Re: How big?
1) As far as heat loss goes, the bigger the better, a la' whales and polar bears: surface area [heat loss] goes up to the square or cube, but the volume [heat retention] grows with the cube or 4th power. An entire order of magnitude.
2) The Japanese used liquid sodium/sulfur batteries for base load smoothing, how large were they?
3) If we can keep smaller but super efficient combined cycle [gas turbine/steam, either natural gas or coal] running at max efficiency with base load smoothing, our carbon footprint gets much smaller per KWh.
Nick G
Reply
bettergreen
1 Comment
Re: How big?
The size of the container for this type of battery would only be limited by the mind of the designer. Combining New building design that planned for the use both of generation of power(wind/solar)and the storage of the same requires thinking outside the box and a willingness to embrace other peoples thoughts instead of "defending your turf". As a designer of wind/solar, small though I may be, Helping to find the solutions far outweights finding the faults in them.
IHS Ken
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