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Title: A cleaner, greener way to store solar and wind energy [flow batteries]
Source:
ScienceMag
URL Source: http://news.sciencemag.org/chemistr ... ay-store-solar-and-wind-energy
Published: Sep 24, 2015
Author: Robert F. Service
Post Date: 2015-09-26 06:57:39 by Tooconservative
Keywords: None
Views: 2014
Comments: 4
With the continuing rise of solar and wind power, the hunt is on for cheap batteries that are able to store large amounts of energy and deliver it when it’s dark and the wind is still. Last year researchers reported an advance on one potentially cheap, energy-packing battery. But it required toxic and caustic materials. Now, the same team has revised its chemistry, doing away with the noxious constituents—an advance that could make future such batteries far cheaper and simpler to build. The new design is what’s known as a “flow battery,” which is usually far larger than your sleek lithium-ion cell or lead-acid car battery. Unlike conventional batteries, flow batteries don’t package all their battery components together. Rather, they separate the chemical power supply—a pair of liquids known as electrolytes—from the electrodes needed to tap that power. This design makes it easy to increase the battery’s energy storage capacity simply by increasing the amount of electrolytes stored in external tanks. That has many engineers eyeing these batteries as a way to store the overabundance of solar and wind power at periods of peak production for use at times when their production is off. At the heart of flow batteries is a sandwich of electrodes, known as a stack, separated by an ion-conducting membrane. The electrolytes are pumped through the stack during charging and discharging. In most designs, when the battery is discharged to provide power, a positively charged electrode strips electrons from molecules in one electrolyte and sends them through a circuit to charge-accepting molecules in the second electrolyte. This process produces positively charged ions in the first electrolyte that travel through the membrane into the second electrolyte, where they balance the charges coming in from the electrons. When the battery is charged, the flow of electrolytes, electrons, and ions is reversed and electrons are dumped into the first electrolyte. Last year, researchers led by Harvard University materials scientist Michael Aziz created a high-energy storage flow battery that used organic compounds called quinones as the electron-storing components of one of its two electrolytes. The other, however, contained bromine, a toxic compound that also readily corrodes steel and other materials commonly used to contain the liquid electrolyte and pipe it around. That forced the Harvard team to contain it with expensive, corrosion-resistant materials, a solution too costly for most applications. Aziz and his colleagues wondered whether there was a way to change the chemistry of their battery so that it wouldn’t need such caustic materials. Most batteries use electrolyte solutions that are either acidic or alkaline, as these are adept at ferrying electric charges from one side of the battery to the other, which is essential for a battery to both charge and discharge. In the team’s previous battery, both the quinone and bromine were dissolved in acidic solutions. The Harvard team realized that a possible bromine replacement was a charge-carrying molecule called ferrocyanide, which sounds dangerous but is actually used as a food additive. Ferrocyanide, however, dissolves in alkaline solutions, not acidic ones. So Aziz and his colleagues tweaked the chemical structure of their quinone—ripping off a couple of sulfur groups and replacing them with pairs of hydrogen and oxygen atoms—in the end converting the compound into one that readily dissolves in an alkaline solution. The scheme worked, and as the researchers report today in Science, the battery readily stores power with only components that are cheap, abundant, and nontoxic. For now, Aziz notes the alkaline quinone battery stores only about two-thirds of the energy per volume as the previous acid-based version. But because it doesn’t require expensive materials to deal with bromine, it’s likely to be far cheaper to produce and friendlier to use. “This is chemistry I’d be happy to put in my basement,” Aziz says. And that may not be far off. A flow battery using the new quinones and ferrocyanide would likely only have to be the size of a couple of hot water tanks to store the energy produced by a conventional home rooftop solar array. “The chemistry sounds great,” says David Keith, an energy expert at Harvard, who was not part of the current study. He notes that most homeowners and small businesses don’t yet need to use batteries as a backup for their renewable power supplies, because they are connected to the grid that can supply power when needed. Aziz agrees, but adds that there are already niche applications where installing batteries makes financial sense. Many businesses, for example, are charged not only for the number of kilowatt hours of energy they use, but also the peak rate at which it is delivered, Aziz explains. That’s because businesses that use most of their power all at once have to have extra electrical power lines to deliver it all, and utilities charge them for it. By installing batteries, those businesses can use stored power to reduce the need for extra electrical connections, and thus reduce their costs. Such applications, Aziz predicts, are only going to grow. If so, cheap, nontoxic flow batteries could become a key part of our energy future.
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#1. To: TooConservative (#0)
Any idea how these would compare to the industry standard, the Trogan T-12?
Well, I know of the Trojan T-12 deep charge batteries, a 12V battery used in series in golf carts and other heavy applications. These would be larger and would likely come packaged in much the same way as these new Tesla home batteries. IOW, you'd have something the size of a water heater (or two) in your basement or garage. Or the size of an old full-size upright freezer. And this would store enough of your solar panel output for days of powering your house. But no lead. No corrosive acids. All very environmentally safe and no fire hazards as with lithium batteries. They aren't saying much in detail but the price of these batteries will depend on how much it costs for the alkaline electrolytic fluid. Anyway, the two big upcoming batteries on the horizon are these flow batteries and the advances we've seen in aluminum batteries. An aluminum battery will be 50%-100% larger than the equivalent lead-acid or lithium batteries. However, unlike a lithium battery that only performs well for the first 300-400 times you recharge it, an aluminum battery can take 8000-9000 full charges with no effect. And aluminum is not toxic and, when you do finally need to replace them, their aluminum can be fully recycled, just like an aluminum can. Aluminum batteries will also be much cheaper to build than lithium batteries and much safer. At a recent demo, they showed how they could drill holes in the casings of these aluminum batteries (fully charged) and they still worked and were not hazardous to the environment or a fire hazard. IOW, the kind of safety you need in home applications where people do dumb things. I only post these articles because there will be some very exciting new battery tech coming in the next few years, much of it the result of corporate and government research projects from the last decade when they all started complaining about how pricey and ineffective the NiCd and NiMH batteries are. There are also some newer types of lithium batteries coming up with higher capacity and more recharge cycles. But I am more interested in storing home-generated power or being able to have reliable electric mowers and other gadgets that can transform general energy usage in the home.
Hmmm....What does that sound like? Oh yeah- a Fuel Cell! Welcome to the wonderful world of the future. And no, I won't be accusing you of posting a "Press Release". This car claims to be powered by "flow batteries"- the Quant Electric Car 900hp Quant EV powered by flow cell battery http://www.gizmag.com/900-hp-supercar-flow-battery/31091/ QUANT e-Sportlimousine with nanoFLOWCELL® drive
900hp Quant EV powered by flow cell battery A big difference between those super-pricey concept cars for only the ultra-rich or for trade show demos and this newer cheaper Greener type of flow battery. Just as there is a big difference between today's fuel cells and the first ones that were made back in the Fifties. Back then, only the military and NASA made much use of them but today they are being hawked to the masses for homes and cars. Flow batteries aren't new but cheap non-toxic flow batteries are very new. I think it will come down to a competition between flow batteries and aluminum batteries. Fuel cells will play a part but I still don't see them dominating in the same way as these others. And lithium batteries are going to become cheaper and have higher recharge cycles in the next few years, extending their hold on the market. Lithium is bad for environment and a fire hazard so I see them as a transitional technology unless they improve safety radically. I'm not sure why everyone thinks only about electric car solutions. What is most needed is home energy storage so that consumers can buy cheap energy at non-peak rates or store their own solar power. Safely. Cheaply. With stuff that can't ever burn down their house or blow it up like the Hindenburg.
#2. To: BobCeleste, Operation 40 (#1)
#3. To: TooConservative (#2)
At the heart of flow batteries is a sandwich of electrodes, known as a stack, separated by an ion-conducting membrane. The electrolytes are pumped through the stack during charging and discharging.
A flow battery is technically akin both to a fuel cell and an electrochemical accumulator cell (electrochemical reversibility). While it has technical advantages such as potentially separable liquid tanks and near unlimited longevity over most conventional rechargeables, current implementations are comparatively less powerful and require more sophisticated electronics...
#4. To: Operation 40 (#3)
his car claims to be powered by "flow batteries"- the Quant Electric Car
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