Forget old batteries. Here comes the energy storage revolution

12 Oct 2017

Energy demands from developing countries are going to grow by about 10 per cent between now and 2040, according to the US Energy Information Administration. By that year, they will be using 65 per cent of the world’s total energy supply.

But although new renewable energy technology can be adopted quickly, the basic energy infrastructure in the developing world is lagging behind. As a result, energy supplies are nowhere near as reliable. And that’s a problem. “In some places we have hospitals that have 12 hours of blackouts a day,” says Enass Abo-Hamed, chief executive and co-founder of hydrogen storage startup H2GO.

If electricity could be stored on-site for when it is needed, outages would be far less frequent. But the cost of existing battery technology is prohibitive. Abo-Hamed and her colleagues are working on an innovative way of storing hydrogen gas that can be burned in fuel cells. The system uses nanomaterials to create a partially flexible sponge that is able to trap hydrogen atoms in its pores. The gas can later be released by heating the structure.

“Once you reach the required temperature, the structure gets distorted and releases the hydrogen,” says Abo-Hamed. It’s a bit like pushing corks out of bottles. But first, you have to get hydrogen. From splitting water molecules (H2O) into hydrogen and oxygen. H2GO will use a water electrolyser for this process. Abo-Hamed says that, based on their calculations, a medium to large hospital in sub-Saharan Africa, for example, would need about 50 litres of water per hour. About 80 to 90 per cent of this supply is returned after the hydrogen is burned to make power, and can therefore be used again.

The H2GO team is now working on developing a cheaper material that mimics the mechanical behaviour of their prototype, so that the technology might be made affordable to buyers in developing countries. Leaving aside hydrogen-based solutions, the vast proportion of the world’s electricity is generated in more conventional ways. And many distributers simply want cheaper and more reliable ways of storing it.

David Howey at the University of Oxford points out that lithium ion batteries, which have more or less conquered the world, still have many shortcomings.n “What we know from testing in a lab is we can take ten cells from the same manufacturer, test them the same way and spread over time – they won’t behave in the same way,” he says.

That variability is worrying if you’re planning to invest in large lithium ion installations. And the energy density of lithium ion – how much energy can be packed into a particular volume – is currently limited. Hence the large-sized batteries being put into electric vehicles today.

Howey says there are a myriad of alternative battery technologies out there, including lithium metal designs. These promise higher capacities, but most are experimental and face their own challenges in terms of becoming commercially viable.

The cost of manufacturing is also a concern when it comes to the production of larger lithium ion batteries that could be used to, say, store power for a building or group of buildings in a neighbourhood. Yet-Ming Chiang, a professor at MIT, has spent years working on novel battery designs. He hasn’t always been successful – one venture, A123, went bankrupt in 2012. But he’s hoping for much better results with 24M, which has developed a “semisolid” lithium ion battery that he thinks could be ideal for grid storage applications.

In conventional lithium ion batteries, several material layers are painstakingly manufactured and sandwiched together. But in 24M’s design, a dough-like, semi-solid mixture is used to make chunky electrodes. “Instead of baklava, we have a brownie,” Chiang says. “Fewer, thicker, softer layers.” The result is a battery that uses a smaller range of materials, has up to 25 per cent greater energy density, and is more resilient to deformation than other lithium ion batteries. “Our design has a 25 to 30 per cent lower cost of materials than a conventional lithium ion battery,” he adds.

Chiang is not planning to manufacture and sell his batteries directly to firms that want to put them in their devices. Instead, he intends to licence the manufacturing technology itself to companies; 24M’s largest investor, for example, is the former national oil company of Thailand, PTT.

But Chiang has other ideas, too. He’s developing a sulphur-based flow battery in which ions flow across a membrane between a sulphur-containing anode and a cathode. When discharging energy, ion flow is enabled by the oxidisation of sulphur compounds in the anode. “The beauty of sulphur is it’s produced as a by-product of refining,” he says.

“Currently, the stockpiles we have of sulphur due to natural oil and gas refining are enormous in terms of the storage we could potentially generate from them.” A separate start-up founded by Chiang, Baseload Renewables, is developing this sulphur battery technology with the hope that it might be used in developing countries to store energy for days or even months. That way, a basic energy supply could be provided to local electricity networks. Baseload Renewables has just been selected to receive investment from MIT accelerator The Engine.

As the renewables industry booms but energy supplies continue to be wasted, better storage technologies will be essential. The race is on to find out who can do it most effectively – and at the most favourable cost.