Is it really possible to hold a charge in nothing but salty water? How about controlling a computer using nothing but the electrical signals in your head? National Geographic expert Leslie Dewan finds out. Further information on official fuel consumption figures and the official specific CO~2~ emissions of new passenger cars can be found in the EU guide "Information on the fuel consumption, CO~2~ emissions and energy consumption of new cars," which is available free of charge at all sales dealerships, from DAT Deutsche Automobil Treuhand GmbH, Hellmuth-Hirth-Strasse 1, D-73760 Ostfildern, Germany and at www.dat.de.
Video by National Geographic

The great green dilemma

There’s lots of excitement right now about our quickening shift to cleaner electricity. But, if we’re to truly make the leap to an electric future, there’s an important hurdle to overcome: we need genuinely clean batteries. While energy storage technology has come on in leaps and bounds, there’s still some way to go in order to lessen batteries adverse environmental side-effects. However, innovative companies are already taking steps to solve this important issue…

Is lithium what we’re looking for?

Lithium batteries are currently the go-to energy storage solution for makers of electric cars, phones, tablets, and laptops. And it’s easy to see why: they’re efficient chargers, easy to dispose of, and have a higher energy density than alkaline batteries.

Dubbed ‘white gold’ by investors, lithium’s demand has seen its price double between 2016 and 2018 as battery makers try to get their hands on this silvery-white alkali metal. Even though there’s a whopping 43 million tons (39 million metric tonnes) of the stuff on Earth, only a third of it is in a form that can be mined; of that, 87 per cent is found in brine waters, mostly in South America’s so-called ‘Lithium Triangle’.

The production process for lithium, or more specifically lithium carbonate, involves drilling holes in salt flats and pumping salty, mineral-rich brine to the surface. This brine is left to evaporate, and the resulting salts are filtered so the lithium carbonate can be extracted. Although a very simple process, it uses large amounts of water and can be time-consuming – taking between 18 and 24 months.

Audi are among those looking for ways to make the production of lithium batteries speedier and more climate-friendly. For instance, valuable elements can be extracted and reused in new products at the end of a battery’s lifecycle; in some cases it’s possible that entire lithium batteries can be repurposed for a second-use, powering transport and factory vehicles. With this in mind, recycling of decommissioned batteries has become a major focus for Audi.

There’s also scope to increase the energy density from these batteries – therefore decreasing their size, and how much lithium is actually required – while also reducing the use of rare and expensive components like cobalt.

Tsuyoshi Hoshino of Japan Atomic Engery Agency’s Rokkasho Fusion Institute recently proposed another idea – a method for recovering lithium from seawater using dialysis – in the journal, Desalination. The system uses a special membrane which only the lithium ion can pass through. Though not yet ready to be commercialized, Hoshino says his osmosis technique “shows good energy efficiency and is easily scalable.”

Are graphene supercapacitors actually super?

While lithium production is being perfected, experts are championing alternatives, like graphene supercapacitors. Despite sounding like they belong on a spacecraft, these may help solve the earth’s energy dilemma. Instead of holding electricity as chemical potential – like alkaline or lithium batteries – supercapacitors store it in an electric field, similar to the way static collects on the surface of a balloon.

The addition of ‘wonder material’ graphene creates supercapacitors that are strong and light. Although it’s still early days, the graphene battery market is predicted to reach $115 million by 2022, with Chinese and Spanish companies using supercapacitors to power everything from laptops to electric motorcycles.

However, there is a very big ‘but’ to all this. Supercapacitors – even graphene ones – can’t yet hold a charge for long. Think how annoying it is when your phone battery plummets, then imagine the same thing happening when you’re in the car miles from a charging station. Not great.

Could we store clean electricity in an equally clean battery?

A battery that’s both practical and environmentally friendly to produce might seem like the Holy Grail, but in Delft, Holland, a group of innovators at AquaBattery believe they’ve found it. The Blue Battery stores power in – you guessed it – water, and could be used to stockpile all the eco-electricity the Netherlands produces, in a 100 per cent sustainable way. So how does it work?

Passing an electic current through salt water splits it into concentrated saline and freshwater – a process known as electrodialysis – storing the energy at the same time. During the second discharging phase, the process is reversed and these two waters are combined, releasing the collected energy – which is then converted back into electric current with the help of special membrane stacks.

It’s a simple, safe technique that has the potential to store huge quanities of electricity for use when needed –making sure a city’s power grid always has enough energy to meet demand, for instance. While the set-up in Delft is currently at a relatively small-scale, AquaBattery director David Vermaas has big plans; he wants to roll out his Blue Battery to places where saltwater and freshwater meet, like the Dutch waterways for example. The energy potential is enormous.

Lithium batteries currently offer the most practical solution to storing energy and are set to remain an integral part of powering a new generation of electric cars. But, in the next decade or so, you might find yourself recharging from a grid supported by Blue Batteries. With increased refinement, they are expected to offer a real alternative that will change our relationship with renewables. Whether it’s in generation, storage, or the powering of an electric vehicle, the hope is that one day, every stage in the energy journey will be 100 per cent green.

Further information on official fuel consumption figures and the official specific CO~2~ emissions of new passenger cars can be found in the EU guide "Information on the fuel consumption, CO~2~ emissions and energy consumption of new cars," which is available free of charge at all sales dealerships, from DAT Deutsche Automobil Treuhand GmbH, Hellmuth-Hirth-Strasse 1, D-73760 Ostfildern, Germany and at www.dat.de.

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