One of the biggest obstacles to electric vehicle (EV) adoption is electric vehicles’ relatively long refueling time. Sure, you can charge while you sleep, and there is DC rapid charging for road trips, but compared to conventional fossil fuel vehicles, it’s still inconvenient and takes extra time. (Editor’s note: Well, that argument is getting much harder to make, as Max Holland explains well here.)
One German company, nanoFlowcell, is showing that there may be a better way to recharge an electric vehicle: by replacing its liquids as fast as a gas car.
The Test Vehicle
Most of today’s electric vehicles run on sealed batteries. The only thing that really goes in and out of the battery cells are electrons and some thermal energy (waste heat) that may build up or need to be added by warming the battery in cold conditions. Unlike older lead-acid batteries, there’s no lid to pop open to check fluid levels and add distilled water as needed. Energy density of lithium ion batteries are a lot better than lead-acid batteries, but they still can’t be replenished that quickly once discharged.
It’s worth noting that nanoFlowcell isn’t the first company or set of researchers to experiment with flow batteries for electric vehicles and other energy storage uses. The idea is attractive, because a good flow battery shouldn’t degrade very quickly, and may go for tens of thousands of hours before needing any parts replaced.
The difference now is that somebody actually built a car that runs on this and tested it for hundreds of thousands of kilometers, both on the track and on public roads in Europe.
The car has two liquid tank and pump systems, with a membrane separating the liquids. When in contact, the system can generate electricity from chemical energy, much like a traditional EV battery does. This energy then powers an unusual 48 volt system to drive the vehicle. Compared to most electric cars, 48V is pretty low. For example, vehicles like the Nissan LEAF and current Tesla models have voltages from 350-425 volts. This makes it much easier to work on the system and makes the vehicle subject to easier low-voltage regulations in many jurisdictions.
The biggest advantage is that you can have another flow battery charging at home or at the equivalent of a gas station, preparing new liquid for the car’s battery, while you drive. To recharge the car, it can charge like any other EV, or you can pump the liquids out and replace them with those from another fully-charged flow battery. Then, drive away.
Longevity
Earlier this month, the company’s QUANTiNO test vehicle passed the 350,000 km mark (that’s almost 220,000 miles, for the metrically challenged). The vehicle’s flow battery showed no signs of damage to the membrane or the pumps, and didn’t seem to have suffered any wear at all. The vehicle’s engineers pointed out that it had driven for 10,000 hours at this point. The company wants to offer these batteries to EV manufacturers and give the system a 50,000 hour guarantee.
If this pans out the way they say it will, that means that the vehicle could make it to over a million miles with no battery degradation. With electric motors also being able to go the distance between rebuilds, this means the drive and battery system should outlast the rest of the vehicle.
The Impact and the Gotchas
While the EV industry is currently working on other solutions, this may provide a solid alternative that could help increase adoption of clean transportation technology. That being said, there are drawbacks to this idea that nanoFlowcell doesn’t discuss on its website.
First, electricity is available nearly everywhere. As I write this article, I’m sitting at an RV park in a small town near the US-Mexican border charging my Nissan LEAF up. Building a rapid charging station is a big challenge, but Tesla, Chargepoint, Blink, AeroVironment, EVgo, Electrify America, and many others prove that it’s possible. Flow battery pumping stations, on the other hand, may be a harder nut to crack.
Take hydrogen fuel cell vehicles for one example. Sure, you can build hydrogen filling stations, but outside of California, there just aren’t many (or any) around. Power lines can bring the juice for EVs and do it without staff or complicated electrochemical machinery in the parking lots where stations are installed. Hydrogen, and possibly flow battery liquids, will have to be charged and recharged somewhere, and maybe brought in trucks like gasoline and diesel.
The challenge of infrastructure puts DC fast charging in a better position to proliferate than flow battery stations. I may be wrong, but that’s what it looks like from where we sit today.
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