Nobody is interested in fuel cells. Thank the obsession with carbon dioxide

lectric cars are wonderful: they have fewer parts, they're quiet, they have no need for fuel injectors, radiators, air filters, spark plugs, or transmissions, they never stall out, and they have more torque at low speed. There's only one problem: you can only drive them about ten feet. Any more than that, your extension cord gets pulled out of the plug and you need a battery.

Well, you might say, ten feet is a long way. But what about fuel cells? A fuel cell uses liquid fuel instead of batteries for energy storage, combining the advantages of electric and gasoline. If someone invented a practical hexane fuel cell, it would be spectacular.

A commercially-available hobbyist-scale direct methanol fuel cell from The Fuel Cell Store. These fuel cells are more sophisticated than the enormous ones used by NASA in the past

Fuel cells never need recharging and they're nearly twice as efficient as combustion engines (over 60% compared to 33%), compensating for the lower energy density of methanol (15.6 vs 33 MJ/L for gasoline). By contrast, lithium-ion batteries store at most 2.43 MJ/L. To make them as energy-dense as gasoline, their capacity would have to be increased by 13.6-fold. If your laptop were powered by a methanol fuel cell, it could run a week on a single fill.

Unlike liquid hydrogen, hydrocarbons and methanol are viable means of energy storage and distribution networks are already in place. To use them, they must be converted to hydrogen in an onboard catalytic reformer. A reformer is a small device inside the fuel cell that converts the fuel either to methanol or directly to syngas. Syngas is a mixture of hydrogen and carbon monoxide, which is never released but used locally in the fuel cell. The science is reasonably well understood, but advances in technology are required to make such reformers truly practical.^[1]

Some papers suggest dimethyl ether as a fuel, as it can be catalytically broken down to two molecules of methanol. Unfortunately, ethers have safety issues due to their tendency to react with oxygen to form explosive peroxides. Peroxides are typically less volatile than the ether and become concentrated when the solvent evaporates. This would turn your car into a Ford Pinto on steroids, even if free radical inhibitors were added.

In a methanol fuel cell, the most significant reaction is oxidation of methanol to carbon monoxide followed by oxidation of carbon monoxide in water:
      CH3OH → CO + 4H+ + 4e−
      CO + H2O → CO2 + 4e−
The e⁻ are the precious electrons and CO is carbon monoxide, which stays at low concen­trations within the cell as it is used up. Each methanol molecule ultimately produces six electrons (or eight according to some sources) and H⁺ ions that are neutralized by OH⁻ formed at the cathode.

The US government sounds enthusiastic about fuel cells, but their focus is on cryogenic hydrogen, which is difficult to transport and store. Industry is hesitant to invest in methanol or hydrocarbon fuel cells because they produce CO₂. They know the government thinks CO₂ is causing a global warming crisis, so any products they make would just be regulated out of existence.

There are still technical hurdles. Better catalysts are needed to speed up the electrochemical oxidation of methanol at the anode, which limits their performance. If methanol crosses over to the cathode, it is oxidized in a corrosion reaction, causing a useless leakage current, so an improved barrier is also needed.^[2]

Some early types of fuel cells, such as alkaline fuel cells, are poisoned by CO₂. Phosphoric acid fuel cells are inefficient and require lots of expensive platinum catalyst. But other types, such as molten carbonate fuel cells, don't need platinum at all and are up to 65% efficient. If the waste heat is captured, overall efficiency rises to 85%. They can use methane and other light hydrocarbons directly instead of H₂ because they run at 650°C.

Unfortunately, the government says, they only last 40,000 hours, or a mere 109.5 years at one hour per day. Of course, since the typical car is essentially a rolling pile of rust after 25 years, this problem is mainly hypothetical.

Cryogenic hydrogen will likely remain impractical in vehicles for the foreseeable future. To sell it to us, they'd have to bombard us with ads telling us how safe hydrogen is, how the Hindenburg disaster was actually caused by a thermite reaction, and how H₂ can easily be stored for weeks at a time below −252.87°C—a smidgen above absolute zero—before permeating through the plastic or leaking out due to embrittlement. True, you might not freeze solid if you stepped in a puddle of it or suffocate (unless you were in a closed structure like, say, a car), and even if your car got rear-ended like a Ford Pinto it wouldn't spill out and blast you into outer space; at most you'd reach low-earth orbit. Converting hydrogen to ammonia for transport creates even worse problems.

The government is tilting the economic balance toward electric by making carbon-based fuels more expensive, almost as if they think batteries are practical. And so a valuable technology goes undeveloped. We are skeptical when scientists on corporate funding tell companies what they want to hear. Maybe we should be even more skeptical about research done for government funding.

jun 05 2022, 9:08 am. updated jun 06 2022, 4:19 am