Last week I wrote an article about a remarkable sounding supercar that uses a revolutionary sort of flow battery that can be recharged with what's implied to be saltwater. The car's design is striking, the specs are very impressive, and the technology seems revolutionary. But it also seems like bullshit.

I felt a little bad after writing that article because I very quickly realized I needed to apply much, much more scrutiny to the remarkable claims the company was making than I did. I expressed skepticism, but what I really needed to do — and what you readers deserve — is an in-depth evaluation of this technology and claims.

For something as crude as the FuelShark, I'm comfortable handling most of the technical side of things. But the company that makes this car, the Quant, they're talking about nanotech and other types of cutting-edge technology that just makes my bountiful ignorance glow red-hot.

That means I need to pull in an expert. Luckily, I've got one: Jalopnik's tamed physicist, Dr. Stephen Granade. I asked him for an in-depth evaluation of nanoFlowCELL's claims and an assessment of how much reality we're actually looking at here, and he didn't disappoint:

A car that runs on salt water! And it uses a crazy new battery design to make it happen! It sounds too good to be true!

Unfortunately, the QUANT e-Sportlimousine probably is too good to be true. There's a kernel of actual technology hidden in the news story about it. Flow batteries are a real thing, and could become a cool alternative to Lithium-ion batteries for cars. I just wish that that kernel wasn't buried in a pile of corporate speak and claims so incredible that I doubt that they're real.

Flow batteries are a way of getting around the problem of scaling up traditional batteries and making them store more energy. Traditional batteries have two electrodes separated by an electrolyte. When you draw electricity from the battery, chemical reactions happen at the electrodes to produce that electricity. The electrodes are both where the energy is stored and where the electricity is generated. That makes it harder to make a single battery that holds a lot of energy. It's one of the reasons that Tesla uses many batteries in a pack rather than one big battery.

Flow batteries separate how the energy is stored from how it's extracted. They have two different electrolytes in tanks, typically metal ions dissolved in a liquid. (Not salt water, though.) The electrolytes flow past a membrane that lets the chemical reaction happen between the two electrolyites, producing electricity. The energy is stored in the electrolytes and extracted by the chamber with a membrane. If you want to store more energy, you can just use more electrolyte while leaving the membrane part of the battery alone. It makes the problem of scaling up battery size much easier. The liquid electrolytes also have a lot of advantages for cars. You could drive a flow-battery car into a recharge station, pump out the used-up electrolyte, and pump in charged electrolyte. Then you'd drive off while the station got to work recharging your exhausted electrolyte. We've gotten very good at storing and pumping liquids for cars, so why not take advantage of that knowledge?

Unfortunately, you can't pack as much energy into flow batteries as you can other kinds. You want batteries to have really high energy density, so that they carry a lot of energy and produce a lot of power for every kilogram they weigh. You have 100 times less energy in a kilogram of Tesla's battery packs than in a kilogram of gasoline. Flow batteries are even less energy dense than Tesla's batteries. One of the problems with flow batteries is that you can only extract energy from the part of the liquid that flows past the metal plates that move the electrons out of one electrolyte, through the circuit the battery's hooked up to, and into the other electrolyte.

Researchers are solving this problem with nanoparticles. Yet-Ming Chiang and his materials science colleagues at MIT have used nanoparticles to, in effect, embed all of these tiny liquid wires in the electrolyte. Those nanoparticle "wires" mean that the battery can reach parts of the liquid that are further away from the metal plates, making it possible to store and extract more energy in the same amount of electrolyte.

I'm guessing that's what the e-Sportlimousine is claiming to use. I say "guess" because nanoFLOWCELL hasn't released detailed information about their flow battery technology. They've barely released any information about their tech. But they have "nano" right there in their name, and their press releases describe how they've come up with a way to pack more energy into a flow battery.

Even without that information, I'm extremely skeptical that the e-Sportlimousine is what it's supposed to be. Not because it runs on sea water — it doesn't, and nanoFLOWCELL hasn't claimed that it does. They've only talked about "metallic salts in an aqueous solution", not table salt dissolved in water. I'm skeptical because of how much better they claim their flow batteries are than the current state of the art. Their press release says that their flow battery has five times the energy density of even Tesla's Lithium-ion batteries. That's an extraordinary claim, and those batteries would revolutionize the portable battery industry. But there's been no proof.

Worse, five years ago the QUANT was "going to be powered by a breakthrough in solar cell technology" and a "Flow Accumulator Energy Storage". An independent test of their solar tech indicated that that technology didn't live up to their claims (as you can read, assuming you read German). Now the QUANT depends on a breakthrough in flow cell technology, one that leading flow battery researchers can't even match. The CTO, Nunzio La Vecchia is a self-described "physicist and autodidact" who is also a musician, pilot, and racing driver. He's one medical degree away from being Buckaroo Bonzai. I'd love for his amazing battery to be real, but past experience tells me that it probably isn't.

A new battery design could lead to a cheap way to address the intermittency of solar and wind power.

I always feel like I'm killing Santa Claus when I talk about something that sounds amazing but is unlikely to pan out. Technology usually improves slowly over time, the way that Lithium ion battery's energy density has been growing by about 9% a year since the 1990s. I say "usually" because sometimes technology really does leap foward, seemingly out of nowhere. But far more often, revolutionary new tech isn't actually revolutionary and will never work. Extraordinary claims require extraordinary proof. In this case, instead of extraordinary proof, we only have overly-breathless press releases.