STORAGE RISK: Storing large amounts of energy, in batteries or other devices, inherently poses risks -- but also offers benefits.
Image: Mariordo/Wikimedia Commons
People still need electricity when the wind isn't blowing and the sun isn't shining, which is why renewable energy developers are increasingly investing in energy storage systems. They need to sop up excess juice and release it when needed.
However, storing large amounts of energy, whether it's in big batteries for electric cars or water reservoirs for the electrical grid, is still a young field. It presents challenges, especially with safety.
The most recent challenge first appeared in May, three weeks after a safety crash test on the Chevrolet Volt, General Motors Co.'s plug-in hybrid. The wrecked vehicle caught fire on its own in a storage facility, raising questions about its lithium-ion battery.
Last week, after a series of additional side-impact crash tests on the Volt battery, the National Highway Traffic Safety Administration (NHTSA) launched what it called a "safety defect investigation" into the risk of fire in a Chevy Volt that has been involved in a serious accident.
Problems have also afflicted spinning flywheels, which allow power plants and other large energy users to store and release powerful surges of energy. In Stephentown, N.Y., Beacon Power's 20-megawatt flywheel energy storage facility suffered two flywheel explosions, one on July 27 -- just two weeks after it opened -- and one on Oct. 13. The company declared bankruptcy earlier this month.
In Japan, sodium-sulfur batteries at Mitsubishi Materials Corp.'s Tsukuba plant in Ibaraki prefecture caught on fire on Sept. 21. It took firefighters more than eight hours to control the blaze, and authorities declared it extinguished on Oct. 5.
NGK Insulators Ltd., the company that manufactured the energy storage system, said it is still investigating the incident's cause and has halted production of its sodium-sulfur cells, which are installed in 174 locations across six countries.
"Clearly, storing large amounts of energy is difficult from a physics standpoint; [the energy] would rather be somewhere else," said Paul Denholm, a senior energy analyst at the National Renewable Energy Laboratory.
He explained that energy naturally wants to spread out, so packing it into a small space like a battery or a fuel cell creates the risk of an uncontrolled energy release like a fire or explosion. Similar issues come up with mechanical storage, whether it's water behind a dam, compressed air underground or spinning flywheels.
Some storage risks are 'grandfathered'
However, these risks are not unique to storing electricity. Fossil fuels, which are technically forms of stored energy, pose plenty of problems in their extraction, refining, distribution and delivery.
"We basically have grandfathered these risk factors. Gasoline catches on fire all the time," said Denholm. Electrical energy storage systems aren't inherently riskier than petroleum or natural gas, according to Denholm, but their risks are different.
The NHTSA shares Denholm's assessment when it comes to cars. "Let us be clear: NHTSA does not believe electric vehicles are at a greater risk of fire than other vehicles," said the agency in a press release earlier this month responding to the Volt fire. "It is common sense that the different designs of electric vehicles will require different safety standards and precautions."
For batteries, the main issue is how they control the heat they generate. "What you really want to avoid is cascading failure," said Denholm. "A failure of any one of those batteries is not a huge event, but if you don't have proper thermal management, a failure in one battery can cause failure in another."
This condition, known as a thermal runaway, happens when a cell fails and releases its energy as heat. This heat can cause adjacent cells to fail and generate heat, as well, leading to melting materials and fires.
See what we're tweeting about
14 Comments
Add CommentThis is an inherently silly and pointless article. Can certain batteries catch fire, yes; can certain batteries explode under harsh conditions, yes; does this need to be planned for in the design, yes, and it already is; will it ever be 100% fool proof, no.
Reply | Report Abuse | Link to thisNow how about our current fuel, gasoline. Can it catch fire under any and all normal driving conditions, yes, only a single spark and you can say bye bye; Can gasoline explode under harsh conditions, of course, that's how we get the car to move in the first place; Is it possible to make it 100% safe, no, not at all, gasoline explode in an oxygen atmospher [period].
inherently, batteries are far supior to gasoline in regards to safety, INHERENTLY! So, why are you even talking about it? Why not talk about the more massive safety concerns with chemical energy storage systems rather than electrical storage systems?
All good points. But the problem is one of image and consumer acceptance. This has considerable potential to harm the image of the Volt and similar vehicles in the mind of the average consumer, with serious consequences for its greater acceptance.
Reply | Report Abuse | Link to thisDon't worry about this problem harming the Volt. When you walk up the vehicle in the showroom and see a sticker price more than $40,000, you won't be thinking about vanishingly unlikely battery fires (you'll be leaving).
Reply | Report Abuse | Link to thisI believe that you are missing the big picture. While gasoline is very highly explosive, the risks and means of control are well understood, and in fact are a mature technology. Note that millions of cars around the world last for many years without exploding spontaneously, as has happened with the electric vehicles mentioned. It should also be noted -adventure movies notwithstanding- that explosions in serious accidents are rare as well.
Reply | Report Abuse | Link to thisAlso, please note that the natural response of a battery to an overload or excessive heat is meltdown and self destruction. Control of that requires electronic battery management subsystems that also must be designed to be inherently fault tolerant. The equivalent energy management system for a gasoline powered car is a well designed tank! That this defect is showing up now with a production of only a few thousand vehicles is a disturbing trend, and must be addressed before serious mass production is contemplated.
Yes, it is more about "new" rather than "accepted".
Reply | Report Abuse | Link to thisWhat I found interesting is how the Volt is safer because it is heavier. I hadn't considered that hybrids could and are significantly heavier than gas equivolent vehicles.
Could the problems with the GM/Chevy Volt be a direct result of their becoming Government Motors? Run by the federal government and the unions, what could go wrong? Poor quality and shoddy workmanship is what. Buy a Ford.
Reply | Report Abuse | Link to thisYes, it's disturbing if someone would stay in their car for hours or even weeks after an accident, just waiting for a battery fire to occur. If you mangled your gas tank and it started leaking all over the ground, I don't think you would stick around for any length of time if you could help it.
Reply | Report Abuse | Link to thisThere are several electric vehicles coming to market and the Volt seems to be the only one having that problem. The Leaf, all electric, has been on the market longer than the Volt and there has not been a single fire with the Leaf. GM killed the electric car a few decades back, and maybe they are trying to do the same thing again by making people believe that the electric battery is unsafe and will burn down your house while you sleep.
Reply | Report Abuse | Link to thisGM is owned and operated by the GOP and everyone knows how the GOP feel about anything that improves or cleans up the environment. I don't believe the American people will allow GM to kill the electric vehicle again because we really do want to get away from fossil fuel forever and clean up our environment.
How do you get that GM is owned by the GOP? It was taken over by the Democrats in charge and given to the UAW, who are 100% dems. I'm not finding any GOP connection at all. Please explain how you came to your conclusion.
Reply | Report Abuse | Link to thisHey, why don't we leave the politics at the doorstep when we come here to discuss scientific issues here at SCIENTIFIC American. That goes for both of you.
Reply | Report Abuse | Link to this@Postman1
Reply | Report Abuse | Link to thisThis has nothing to do with politics. And the Volt has been rated safer than gasoline equivolents. This is just a bad title with a decent article covering battery safety issues. I'd much rather store energy in a lithium car battery than as gasoline in a tank.
Thank you editor, for removing the spam!
Reply | Report Abuse | Link to thisThe killer consideration is simple! IF I run out of gas, I walk to the station to buy a can. Or the tow truck driver has a can.
Reply | Report Abuse | Link to thisWith electric -- Tow it a charging station. But, you'll only be 10 miles from home!
This risk can be very real even when relatively small amounts of energy are stores. I'm familiar of cases where ordinary deep-cycle marine batteries hooked together in series to increase voltage have shorted out and burned through an aluminum hull in a few seconds. It's not hard to imagine how a battery with enough energy to power an electric car could be very dangerous under some circumstances, either by poor design or because of an accident. Simply beause a large amount of stored energy is not a flammable liquid like gasoline does not make it automatically safe.
Reply | Report Abuse | Link to this