tag:theconversation.com,2011:/id/topics/redox-flow-batteries-23022/articlesRedox flow batteries – The Conversation2016-11-11T09:35:06Ztag:theconversation.com,2011:article/686022016-11-11T09:35:06Z2016-11-11T09:35:06ZWhy batteries have started catching fire so often<figure><img src="https://images.theconversation.com/files/145427/original/image-20161110-25228-1oicn76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Watch out. </span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-498493102/stock-photo-3d-illustration-of-smartphone-battery-explosion-exploding-mobile-phone-overheating-battery-cells.html?src=jYxTyS8Z9G5nrGkJTcMTVQ-1-37">Igor Zh.</a></span></figcaption></figure><p>All our lives we have relied on batteries in everything from mobile phones and cars to hand torches, but confidence in the technology has deteriorated of late. Many airline passengers <a href="http://www.telegraph.co.uk/technology/2016/10/17/airline-ban-on-samsung-galaxy-note-7-widens-as-concern-grows-abo/">have had to</a> surrender their Samsung Galaxy Note 7 phones in recent weeks because their batteries are considered a fire risk, while those left in baggage holds have delayed aircraft and caused angst to travellers. </p>
<p>These batteries were supposedly the remedy for a previous design that saw 2.5m units <a href="http://www.sciencealert.com/samsung-is-recalling-2-5-million-galaxy-note-7-smartphones-over-exploding-battery-fears">recalled</a> in September when they too were deemed a fire risk. <a href="http://www.cbsnews.com/news/lithium-battery-fire-risk-samsung-galaxy-note-7/">Other</a> mobile phone batteries have also been <a href="https://www.theguardian.com/technology/2016/oct/21/iphone-7-car-fire-australia-exploding-battery-samsung">ignition-prone</a>. </p>
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<span class="caption">Hover bovver.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/136653096@N08/23758306572/in/photolist-CcrwPo-4GTnqa-buUXVJ-8RjVDj-CVRZgo-fwAUH2-b4QC8x-Bmx3mW-cAMBbL-errybf-abMmST-axsWHQ-a5Lfvc-2R5JmN-eB5dhv-qhHDrh-dRUV9H-baD9V-9ApMme-agqEwR-D1CUiU-atuWEe-dS1wmf-3BdwUD-5S9rUP-5RdskC-9HQzKy-4ha64L-dBEhkL-6C52Qf-9bDfbj-7M24eU-8WFPv5-cgmgFy-3Xnciz-bsXMMT-dBCkKM-2kgqFy-3fen4i-6eyWsR-zasQ1d-zPUXKf-zat4xJ-BeRqrK-zVzCQM-DyrHyd-8pvkFW-dpRxJm-9zW56W-dBHGNm">Derin Khsro</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>Meanwhile, airlines <a href="http://news.sky.com/story/airlines-ban-hoverboards-over-battery-fire-risk-10336302">banned</a> hoverboards a few months ago, again because their batteries were considered a fire risk. And we are seeing hundreds of incidents of battery fires in electric vehicles, <a href="http://www.scmp.com/news/china/policies-politics/article/1847086/chinas-industry-regulator-orders-safety-checks-green">particularly</a> in China. What’s the cause of all this trouble?</p>
<h2>Enter lithium</h2>
<p>The story starts in the early 1990s with the arrival of lithium-ion batteries as a <a href="http://www.springer.com/la/book/9783319191072">common feature</a> in phones and other devices. Lithium is a lightweight metallic element which is less toxic than previous battery materials such as cadmium or lead. Unlike earlier “single use” batteries, they can normally be recharged thousands of times. </p>
<p>The other clever innovation in lithium-ions lies in the detailed compact structural design of the layered battery. These optimise the thermal pathways and the accompanying software-driven power system control that (normally) avoids overcharging and over-discharging the cells. </p>
<p>These designs have become more and more refined since the mid 1990s thanks to voracious investment in the technology. The energy density that the cells can achieve <a href="http://batteryuniversity.com/learn/archive/the_high_power_lithium_ion">has grown</a> from 100 watt hours per kilo to 270 watt hours per kilo, which means you can have far more power in a smaller space. This has of course been crucial for the advance of modern consumer electronics in which the size and weight of devices are critical selling points. </p>
<p>But with more energy comes more heat, and when things get hot inside a battery the packaging and physical space for expansion become increasingly critical. The race to produce better and better products and capture market share from rivals has required an enormous amount of manufacturing. In the process, it looks as though insufficient consideration has been given to these heating issues, and that new products are emerging that have not been fully time-tested. </p>
<p>This has resulted in batteries in which sudden friction or external heat can lead to a spontaneous explosion. Not only does this cause damage itself, it sometimes sets the surroundings on fire. We started seeing these problems about a decade ago, but now it has become more common – evidently with results that can be disastrous for the companies in question. </p>
<p>From a consumer point of view, there a couple of possible answers: accept shorter battery lives and recharge your device more often; or adopt my principle of being a late adopter of frontier technologies. At least being a late adopter only means waiting about six months these days.</p>
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<a href="https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=418&fit=crop&dpr=1 600w, https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=418&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=418&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=525&fit=crop&dpr=1 754w, https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=525&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/145429/original/image-20161110-25228-69kswz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=525&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘I’m the firestarter.’</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/pic-327590033/stock-photo-mobile-phone-battery-explodes-and-burns-due-to-overheat-danger-of-using-smart-phone.html?src=jYxTyS8Z9G5nrGkJTcMTVQ-1-0">wk1003mike</a></span>
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<h2>Future-proofing</h2>
<p>One might ask if there are other dangers lurking in the wings. The answer is yes, unfortunately. The investment appetite for batteries is producing a range of devices for large-scale use, such as battery parks for future residential areas and what are sometimes referred to as <a href="http://www.smartresilient.com">smart and resilient cities</a>. These parks would be used to smooth the power supply, offer emergency storage and store power from sources like wind farms that can’t produce all the time. </p>
<p>The concept is excellent. Various systems using <a href="http://energystorage.org/energy-storage/technologies/redox-flow-batteries">redox flow batteries</a> containing either lithium or vanadium are already being used to power residential areas in the US and Europe. <a href="http://energystoragereport.info/bosch-energy-storage-vanadium-redox-flow/">For example</a> the small town of Braderup in northern Germany has a system that produces 2MW of power and can store 2MWh – <a href="http://www.ewea.org/wind-energy-basics/faq/">roughly</a> three hours of output from the average onshore wind turbine, for instance. In Washington state in the US, the system pictured below is used to power laboratories. </p>
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<a href="https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/145432/original/image-20161110-25058-96vvnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Vanadium redox storage system.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Vanadium_redox_battery#/media/File:1_MW_4_MWh_Turner_Energy_Storage_Project_in_Pullman,_WA.jpg">Wikimedia</a></span>
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<p>China <a href="http://www.raeng.org.uk/publications/reports/future-of-energy-storage-technologies-and-storage">has been</a> a leading player in the sector. Current experimental facilities at Zhangbei, a town near Beijing, are reported to be testing systems at 14MW and recently <a href="http://en.cnesa.org/featured-stories/2016/6/8/energy-storage-china-conference-2016-review-chinas-energy-storage-market-to-reach-642-gw-by-2020">announced</a> plans to create a single 500MWh storage facility with an intention to deliver 64GW of power across China by 2020 – <a href="http://www.boiseweekly.com/boise/megawhat/Content?oid=3433953">enough for</a> perhaps 50m homes. </p>
<p>The problem is that the sheer intensity and scale of energy in such parks poses a potential serious explosion and fire risk. If we are to avoid such consequences, designers will need to learn the lessons from smaller batteries. Close attention to safety and proper testing will be essential. </p>
<p>Aside from these risks, we also need to bear in mind that batteries are highly resource consuming. The high cost of reusing and recycling batteries is also rarely talked about. In short, the real <a href="https://theconversation.com/when-the-wind-blows-we-must-capture-it-for-a-calmer-day-14909">challenge</a> and <a href="https://theconversation.com/the-missing-link-why-australia-needs-energy-storage-10846">opportunity</a> is to seek to store energy without using batteries at all. That, however, is another story entirely.</p><img src="https://counter.theconversation.com/content/68602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Andrew Williams does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>They used to be boring. Now they’re little arsonists.Richard Andrew Williams, Principal and Vice Chancellor, Heriot-Watt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/577752016-05-12T13:58:53Z2016-05-12T13:58:53ZVanadium: the ‘beautiful metal’ that stores energy<figure><img src="https://images.theconversation.com/files/122288/original/image-20160512-16435-1kxpxyp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The metal is extracted from brightly coloured ore.</span> <span class="attribution"><span class="source">farbled / shutterstock</span></span></figcaption></figure><p>An unheralded metal could become a crucial part of the renewables revolution. Vanadium is used in new batteries which can store large amounts of energy almost indefinitely, perfect for remote wind or solar farms. And what’s more there is loads of the stuff simply lying around in industrial dumps.</p>
<p>Don’t let the dumpster diving put you off – never mind gold or silver, vanadium may just be the most beautiful metal of all. It’s the 22nd most abundant element in the Earth’s crust, though it’s rarely found naturally in its metallic form. Instead, vanadium can be found in <a href="http://www.sciencedirect.com/science/article/pii/S0009254115300401">more than 100 different minerals</a>. </p>
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<figcaption>
<span class="caption">Colours of vanadium.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Vanadiumoxidationstates.jpg">Steffen Kristensen</a></span>
</figcaption>
</figure>
<p>Once extracted and dissolved in water, various forms of vanadium turn into bright, bold colours. It’s even named after “<a href="http://www.rsc.org/periodic-table/element/23/vanadium">Vanadis</a>”, the old Norse name for the Scandinavian goddess of beauty, Freyja. </p>
<p>Vanadium is not only beautiful, but also strong. Adding small percentages of it creates exceptionally light, tough and more resilient <a href="http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/metalsanduses/extractingmetalsrev8.shtml">steel alloys</a>. Henry Ford was the first to use it on an industrial scale, in the 1908 <a href="http://ophelia.sdsu.edu:8080/henryford_org/06-15-2014/exhibits/showroom/1908/chassis.jpg">Model T car chassis</a>, and today the vast majority of vanadium is used in structural steel, mainly to build bridges and buildings.</p>
<h2>Vanadium flow batteries</h2>
<p>The unique properties of vanadium make it ideal for a new type of batteries that may revolutionise energy systems in the near future – <a href="https://theconversation.com/redox-flow-batteries-could-be-the-answer-to-our-energy-storage-needs-51496">redox flow batteries</a>.</p>
<p>Batteries store energy and generate electricity by a reaction between two different materials – typically solid zinc and manganese. In flow batteries, these materials are liquid and have different electric charges. Both are pumped into a “cell” where the electric current is generated. A tiny membrane separates the two liquids, so they are able to react but don’t come into direct contact.</p>
<p>Vanadium is used in these batteries as it can convert back and forth from its various different states, which can carry different positive charges. As only one material is used, the risk of <a href="http://onlinelibrary.wiley.com/doi/10.1002/er.3260/full">cross contamination</a> is eliminated. The liquids have an indefinite life, so the replacement costs are low and there are no waste disposal problems. Also, the battery is extended to a potentially infinite lifetime. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/0Uk0GQNgtqg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Vanadium flow batteries.</span></figcaption>
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<p>In flow batteries, the energy production and capacity are independent. Energy is stored in tanks, whereas the capacity depends only on the amount of liquid stored. This provides a great design flexibility that other batteries do not allow. They are also safer, as the two liquids don’t mix causing a sudden release of energy. Even President Obama is <a href="https://www.youtube.com/watch?v=iBgENqVLJLs">impressed</a>.</p>
<h2>The new energy reservoir</h2>
<p>Vanadium flow batteries are too big and heavy to replace the lithium batteries found in your phone, however. These batteries are instead used for large stationary long-term energy storage, or to <a href="http://onlinelibrary.wiley.com/doi/10.1002/er.1863/full">supply remote areas, or provide backup power</a>. They’re the basis for a more efficient, reliable, and <a href="http://pubs.acs.org/doi/abs/10.1021/bk-2012-1096.ch007">cleaner electrical energy market</a>.</p>
<p>Energy storage is one of the main factors limiting the spread of renewables. When solar and wind power is produced at the wrong time of day we need to <a href="https://theconversation.com/when-the-wind-blows-we-must-capture-it-for-a-calmer-day-14909">store it to use it</a> during the evening demand peaks. Studies have shown that vanadium batteries can be a <a href="http://www.sciencedirect.com/science/article/pii/S0306261915001610">sustainable solution</a>.</p>
<p>When we can create huge stores of energy to access as required, we will be liberated from the need to maintain rapidly-accessible energy generation such as coal or gas. Vanadium batteries can be a reservoir of energy much in the same way as we use actual reservoirs to store rainwater for later use.</p>
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<figcaption>
<span class="caption">Strengthened with vanadium.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/thehenryford/3641577202">The Henry Ford / Life magazine</a></span>
</figcaption>
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<p>The ability to store electricity would reduce reliance on gas and coal. In turn this would increase fuel security and cut CO<sub>2</sub> emissions, helping to meet agreed emissions targets. No wonder then that the EU considers vanadium a <a href="http://goo.gl/UPgt2G">critical metal</a> for strategic energy technologies. </p>
<h2>The hunt for vanadium</h2>
<p>The metal is mined, and supplies are currently dominated by <a href="http://www.sciencedirect.com/science/article/pii/S0959652615003078">China, South Africa, Russia and the US</a>. Vanadium has a medium risk of supply shortage and a <a href="http://pubs.rsc.org/en/content/chapterpdf/2013/9781849737340-00001?isbn=978-1-84973-616-9&sercode=bk">high political risk</a>. </p>
<p>However, as vanadium can be a byproduct of other sorts of mining, about 70% of the vanadium above ground is unused, left in <a href="http://link.springer.com/article/10.1007%2Fs11783-013-0585-1">industrial wastes</a> such as mine tailings, debris or steel slags. In fact, a study I published with colleagues last year estimated that <a href="http://www.sciencedirect.com/science/article/pii/S0959652615013396">43% of the annual global production of vanadium</a> could be recovered from <a href="https://theconversation.com/wealth-in-waste-using-industrial-leftovers-to-offset-climate-emissions-49249">alkaline wastes</a>, such as steel slag, red mud, fly ashes from coal energy production, and construction and demolition waste.</p>
<p>But there isn’t yet a firmly established technology to recover this vanadium. Certain <a href="http://www.sciencedirect.com/science/article/pii/S0301479715000766">bacteria and fungi</a> can extract more vanadium from industrial wastes, and <a href="https://www.researchgate.net/publication/264976108_Process_development_for_recovery_of_vanadium_and_nickel_from_an_industrial_solid_waste_by_a_leachingesolvent_extraction_technique">various</a> <a href="https://www.researchgate.net/publication/284721163_Recovery_of_vanadium_from_alkaline_wastes_leachates">solutions</a> for turning this into useful metal are under development. But we still need to come up with a better way to reach potential sources of this beautiful metal.</p><img src="https://counter.theconversation.com/content/57775/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helena I. Gomes receives funding from Natural Environment Research Council (NERC) under grant NE/L014211/1.</span></em></p><p class="fine-print"><em><span>Helen Abigail Baxter receives funding from Natural Environment Research Council (NERC) under grant NE/L014211/1. This article does not reflect the view of the research councils.</span></em></p>A metal found in industrial wastes could help store solar and wind energy until it’s needed.Helena I. Gomes, Postdoctoral researcher in Environmental Sciences, University of HullHelen Abigail Baxter, Post Doc Research Assistant, Department of Geography Environment and Earth Sciences, University of HullLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/514962015-12-03T11:08:49Z2015-12-03T11:08:49ZRedox flow batteries could be the answer to our energy storage needs<figure><img src="https://images.theconversation.com/files/104122/original/image-20151202-22467-1y6f69u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Sinisha Karich/shutterstock.com</span></span></figcaption></figure><p>How to store energy has become as important a challenge as how to generate it. The types of batteries that power our electronic devices or vehicles are tried and tested, but they’re not suitable for really large-scale energy storage – the sort of batteries that can power whole communities, key emergency services and critical infrastructure. </p>
<p>Making the jump from small to large capacity batteries that could provide back-up for the national grid in times of high demand has proved difficult. Lithium ion batteries offer high power density in a compact size and have many uses, although concerns have arisen about their <a href="http://batteryuniversity.com/learn/article/safety_concerns_with_li_ion">potential to cause fires</a>. Engineers usually encase the battery in a fire-proof cell, but this eats into the battery’s lightweight advantage. </p>
<p>One technology focused on meeting large power needs is the <a href="http://energystorage.org/energy-storage/technologies/redox-flow-batteries">redox flow battery</a>, with <a href="http://www.rongkepower.com/">Ronke Power</a>, launched at the Dalian Institute of Chemical Physics in China 12 years ago, a leading player. </p>
<p>Like other batteries, a redox flow cell contains electrolyte solutions and a positive and negative terminal, around which electrons flow when the circuit is connected. If the battery is not charged, the electrolyte gradually loses its stored energy. How the redox flow battery differs is that in order to maintain energy, fresh electrolyte is continuously pumped into the battery. </p>
<p>The battery, or converter as it is called, is supplied with positive and negative electrolyte solutions held in separate plastic storage tanks. When the electrolyte solutions are supplied to the converter, power is instant and can be varied simply by controlling the flow of electrolyte.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=436&fit=crop&dpr=1 600w, https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=436&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=436&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=548&fit=crop&dpr=1 754w, https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=548&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/104120/original/image-20151202-22439-3vhe4b.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=548&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A vanadium-based redox flow battery.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Vanadium_battery.svg">Paj.meister</a></span>
</figcaption>
</figure>
<p>An important advantage of redox flow is that it’s relatively low-cost. The converter stays the same size for a given power density, but the duration power can be extended from four hours to more than 12 hours simply by installing larger plastic storage tanks to hold more electrolyte. The electrolytes’ charge can be regenerated through connection to electrical power to reverse the discharge process – in other words, when mains power is connected the tanks charge, and when mains power fails the tanks discharge as back-up. </p>
<p>These are both practical and economical batteries. Several types exist such as zinc bromide, polysuplhides, and zinc-cerium, but it’s vanadium-based batteries that are now most common, for a number of environmental and cost considerations.</p>
<p>A drawback compared with lithium ion batteries is the energy density – the size of the installation is large, although I see this as a positive way to differentiate those uses below 20MW (small, lithium ion batteries), and larger installations of redox flow batteries providing 20MW or more.</p>
<h2>Changing times call for energy storage</h2>
<p>Several changes are occurring that make the need for high-capacity energy storage more pressing. Globally, people are moving from rural areas into cities, concentrating the population in smaller areas and placing greater strain on the energy grid. This means that any disruption has a greater impact and is felt by more people, with an economic impact from the effects on industries such as aerospace, petrochemicals, oil and gas, and engineering.</p>
<p>Another change is the surge in renewable energy generation, part of the jigsaw that will ensure sustainable, reliable and competitive energy production into the future. Booming installations of wind and solar generation have brought about a pressing need to integrate these irregularly generating energy sources into the grid. </p>
<p>It’s particularly obvious, however, that wind energy generated overnight when power demand is low is wasted. If wind farms had proper energy storage systems, this energy could be stored until it was needed, meaning the capital invested in wind farms could be more fully used, something which could <a href="http://www.technologyreview.com/news/514331/wind-turbines-battery-included-can-keep-power-supplies-stable/">double the power generated</a>. </p>
<p>Other systems could also benefit, such as municipal waste systems based on anaerobic digestion of organic waste into methane gas. This natural process continues around the clock, so if power was generated from gas continually and linked to energy storage it would provide the same benefits. Building an energy storage system that’s high-capacity and financially viable is key.</p><img src="https://counter.theconversation.com/content/51496/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Atkins does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We already have them in many sizes – but we’re still looking for a battery to store truly large amounts of energy.Martin Atkins, Professor of Green Chemistry, Queen's University BelfastLicensed as Creative Commons – attribution, no derivatives.