Don’t recharge EV batteries, fill them
Denis Droppa looks at the advancements being made in much faster pit stops for electric cars
While the driving range of electric vehicles (EVs) is improving, the long time it takes to charge them (along with their expensive price tags) is one of the main reasons consumers have been slow to embrace battery-powered cars thus far.
EVs take several hours to recharge, and even the quick-charging stations being set up in SA take about 72 minutes to charge a vehicle from zero to 80% — far longer than the couple of minutes it takes to fill up a petrol or diesel car.
However, there could be a clever new solution: batteries that instead of being charged can be refilled in minutes at a network of converted petrol stations.
Scientists are working on flow batteries that would allow motorists to drive until the battery electrolyte in their electric car is depleted, and then simply fill up their car with new electrolyte — taking the same time as it would to fill up with petrol or diesel.
Like the lithium-ion batteries used in most EVs in use today, flow batteries produce energy through chemical reactions between the ends of the battery and a liquid electrolyte. The difference is that the flow battery’s electrolyte, instead of needing a recharge when it’s depleted, is simply replaced with a freshly-charged liquid.
Flow batteries have been around for a few decades but their considerable size and weight have made them impractical for use in vehicles so far. Scientists are now working to make them smaller and increase their energy density.
It’s not known how soon flow batteries might make it into production or how much the electrolyte would cost, while setting up a network of filling stations would no doubt be a challenge. However, the technology could be a potential game-changer in terms of making EVs more popular.
In a related development, Australian-Israeli company Electriq-Global (www.electriq.com) claims to have developed a water-based battery fuel made of 60% water and a 40% chemical mix. The liquid fuel reacts with a catalyst to release hydrogen using hydrolysis, then harnesses it to create electricity in a hydrogen fuel cell to power the car’s electric motor.
The Electriq-Fuel claims to have twice the range and half the price of green energy competitors like lithium-ion batteries or compressed hydrogen, but also with zero emissions. Spent fuel is captured and taken back to a plant where it is replenished with hydrogen and water for re-use.
“The innovative fuel is a cost-efficient alternative to batteries and compressed hydrogen,” claims Guy N Michrowski, CEO of Electriq-Global.
“When compared to green-energy storage solutions like lithium-ion batteries or compressed hydrogen, Electriq-Global achieves a greater range at a lower cost. The energy density potential of the technology is up to 15 times that of electric batteries currently in use in electric vehicles.”
Running the Electriq car is claimed to cost $25 (R347) per tank compared with $50 (R694) for unleaded petrol.
The company says electric buses powered by its fuel achieved a range of 1,100km, with refueling taking five minutes. That's compared with a range of 350km and 300 minutes (five hours) of charging for battery powered buses.
The company claims the fuel is safe, nonflammable and easy to use and to transport, unlike compressed hydrogen.
Demonstration and prototyping projects are expected to be launched in 2020.
Meanwhile in India, a Bangalore-based company called Log 9 Materials claims to have made a graphene-based metal-air battery that runs on aluminium, air and water that gives an electric car a range of 1,000km. It works by degrading aluminium into a hydroxide, which produces electricity to drive the car, and the graphene used in the electrode is claimed to increase battery efficiency by five times at one-third of the cost.
The advantage, says Log 9, is that you don’t have to charge the car. Instead you refuel the car with water every 300km, and every 1,000km you have to change the aluminium, which takes 10-15 minutes. This is a lot quicker than charging an electric car and Log 9, which hopes to launch its battery by 2020, says the process discharges into aluminium powder which can be recycled back into aluminium plates.
Hydrogen fuel cells
There are existing electrified cars that can be fuelled up quickly, namely hydrogen fuel cell cars like the Toyota Mirai and Honda Clarity FCX. They mix hydrogen and oxygen inside a fuel cell stack to produce electricity, which powers an electric motor.
Their advantage over regular EVs is that they have longer ranges and can be filled up fast, but the technology’s very expensive and fuel-cell cars are about double the price of a regular petrol or diesel car.
Another major stumbling block would be the high cost of building the widespread infrastructure of hydrogen filling stations.