Molten metal may not be what you want in your smartphone battery, but it turns out to work great for larger grid-scale batteries. MIT engineers have created devices that can provide up to 20 times as much current as lithium-ion batteries with the same electrode area, according to New Scientist.
The new battery simply consists of tanks filled with three liquid layers kept at 1,292 degrees F (700 degrees C). Molten magnesium sits on top, and antimony sits on the bottom. The middle layer consists of a compound mixture of the two outer layers.
Charging the battery with electricity breaks down the middle layer, and thus enlarges the upper and lower layers, while discharging reverses the process, in a chemical reaction that releases electrons to provide power. Once running, the battery also creates enough self-sustaining heat to keep everything deliciously molten.
A battery as large as a shipping container could deliver a megawatt of electricity, or enough to power about 10,000 100-watt light bulbs for several hours. Its cheaper material costs compared to lithium make it a more cost-effective candidate for scaling up the power grid.
Some utility companies and cities have already turned to sodium sulfur batteries as backup power that can ease reliance on the aging transmission grid -- the Texas town of Presidio recently charged up the largest battery of this type in the U.S. But the molten metal battery technology could provide part of a newer energy infrastructure that supports a growing variety of renewable energy sources.
[via New Scientist]
I got first comment!
Surge64, u r a tool.
What the heck is a 100 watt light bulb? Is that one of those old things that Edison invented that is illegal in California, nobody uses anymore and has no relevance to anything? Can't you use a modern analogy to describe the power of megawatt?
On an "Intelligent Grid" with both Wind, Tidal, and Solar inputs, and with some consistent Nuclear seed power, the whole idea of using all the electricity produced in gainful ways for mankind becomes a possibility - As the American dollar falls, harbinger to an American conversion from a foreign, liquid energy economy to a domestically created Solar, Wind, Wave, Hydro, Tidal, Geothermal, Nuclear electric based economy, we see the electric car charging as a useful "Ballast" to the system, not a detrimental "load". Ideas are changing, but Americans still trade oil generated dollars for Nuclear generated Chinese goods and lose big-time both ways on the exchange! Molten batteries of industrial proportion could make Solar from the South Western deserts a viable reality if Capitalists are forced to "pull the Oil Plug" by the shrinking dollar, and go to perpetual or renewable power as China has and is doing as fast as they can! Even smaller, cheaper, more energy specific reactors such as the Tsinghua University of China's Pebble bed High efficiency Reactors could be modulated or Ballasted for varying demand by such powerful batteries - A small reactor furnishing the huge daylight loads and charging the batteries in times of lower demand? America is not totally lost, only floundering, wounded by its poor dollar performance and the need to convert from foreign liquid energy economy to domestic electric economy, and we fear change like all little children faced with a new reality do! Here's hoping for a graceful maturation for America, no longer sweetheart to the world, and not yet the young woman we want her to become! May these great new batteries help her on her way.
Popsci can you please use units of energy like megawatt HOUR rather than or in addition to things like light bulb time.
Sorry meant units of power not energy ^_^
So, just how much of this increased capacity will be required to keep the metal at 700C?
Not sure that there is any net gain once the power to heat the metal is subtracted.
I like the concept, I really do. But I also have to wonder if widespread use of such batteries could have a compromising effect on our power grid in the event of a widespread failure that lasts days or weeks. For example, let's say that in 20 or 25 years we have tons of huge molten metal batteries across our power grid to balance a large amount of renewable but not sustained sources (ie wind, solar, etc). Then let's suppose that a very strong solar flare fries the grid. If this were to happen today, it would take many years to get power up and running everywhere again. But let's say we are better prepared in the future and that most areas can be back up in a matter of months.
Now here's the question: With no inputs or outputs on most of these batteries for weeks or months, will the temerature of the metals drop until the metals solidify completely? I would assume so. If that is the case, and much of our infrastructure is variable (wind, solar), would it then take longer to bring the system back up? Would we have to run nuclear and coal for days or weeks of time to pump enough juice into the system's batteries in order to make them molten again so we can start once again using all our variable renewable sources? Will solidification and reheating of the batteries cause them problems or failure?
Energy storage certainly needs to be addressed. But as we become more and more dependent on our energy grid for essential daily functions, I think we need to look at all the implications of future technologies in terms of worst case scenarios.
@ holstein13, Obviously you don't understand. A 100 watt light bulb is your everyday incandescent bulb. Not those fancy-shmancy florescent bulbs that can't work for crap, but the regular, reliable, been around for ages bulbs with a little wire in it. And if those are illegal in California, than most Californians would be under arrest right now.
Do the ends justify the means. I see utility companies using this technology to augment storing renewable energy devices however it takes a lot of energy and time to heat it up and to keep it heated. One ray of hope is throw a few "Pebbles" in the holding tank to keep it warmed-up for years...
"The base of the PBR's unique design is the spherical fuel elements called "pebbles". These tennis ball-sized pebbles are made of pyrolytic graphite (which acts as the moderator), and they contain thousands of micro fuel particles called TRISO particles. These TRISO fuel particles consist of a fissile material (such as U235) surrounded by a coated ceramic layer of SiC for structural integrity and fission product containment."
The self contained radioactive pebbles can get as hot as 1,600 C.
magnesium is highly inflammable, there are some dangers in using thermal batteries. Recent explosion killed 10.
Yay we invented a battery that will store a megawatt of power for an hour. All we need to do is heat it up for three hours using 6 megawatts! Oh, wait...
@ford2go: Batteries like this are typically stored in a double walled vacuum container - basically a large thermos. Once it is warmed up to operating temperature the internal resistance is more than sufficient to make up for thermal losses and it will stay molten for a long time even without any current flow.