Slashdot Mirror
Enzymes Make Electricity From Jet Fuel Without Ignition
An anonymous reader writes University of Utah engineers say they've developed the first room-temperature fuel cell that uses enzymes to help jet fuel produce electricity without needing to ignite the fuel. These new fuel cells can be used to power portable electronics, off-grid power and sensors. A study of the new cells appears online today in the American Chemical Society journal ACS Catalysis. "The major advance in this research is the ability to use Jet Propellant-8 directly in a fuel cell without having to remove sulfur impurities or operate at very high temperature," says the study's senior author. "This work shows that JP-8 and probably others can be used as fuels for low-temperature fuel cells with the right catalysts."
Important question: efficiency?
This isn't a heat engine; therefore, it isn't subject to the Carnot efficiency limit that is a key reason that internal combustion engines have such a low maximum theoretical efficiency in terms of extracting energy from the fuel.
Hydrocarbons are actually a great energy store for a vehicle: they are thermally stable/don't discharge over time, it's fast & trivial to "recharge" the energy store, and hydrocarbons have orders of magnitude more energy per mass than any form of battery, which improves vehicle efficiency by reducing the mass that has to be lugged around. However, the internal combustion engine is a wastefully inefficient, complicated machine. Ideally, we could get the best of both worlds with a hydrocarbon fuel cell that efficiently produces electricity to drive electric motors for a vehicle. There are other technologies that could potentially accomplish this, such as the solid oxide fuel cell.
Don't conflate the energy store (hydrocarbons) with the stored energy (e.g. fossil fuels). There is no reason we cannot create hydrocarbons at will using various approaches. Biodiesel from algae is one example as well as "reverse combustion" via more industrial processes (e.g. the Fischer-Tropsch process). Some catalytic processes have been created that use solar power to create hydrocarbons.
Personally, I prefer the idea of large nuclear plants creating hydrocarbons from atmospheric CO2. As a bonus, we would get to keep our existing petroleum distribution infrastructure while our vehicle fleet becomes carbon neutral. Backwards-compatible carbon neutrality FTW?
The sponsor is the US military. They have standardized on JP-8
By the way, the original post was wrong when it said JP-7. That's a specialty fuel used by the SR-71 and hypersonic X-51 Waverider. The research was done using JP-8.
From a logistics point of view, having a fuel cell that uses the same stuff you use in aircraft, tanks, and trucks is a big win. A fuel cell that is a drop in replacement for existing generators that use JP-8 would be a big deal. That;s why the military is interested.
Why is Snark Required?
It is a bacterial enzyme. The purification methods in the article are easily scalable to an industrial scale. The only thing that is not clear are what are the yields. However, there is a significant room for optimization of the yield and this is something that is not hard to do. They have also not done any work on optimizing the stability of the enzymes. So I guess there is a lot of room for improvement. Enzymes are used quite a lot on industrial scale in things like laundry detergents for example.
JP-8 is nearly identical to Jet A-1, which is the fuel used in commercial jet airplanes and is mostly kerosene. It's not very aromatic and is harder to ignite than gasoline. You may be thinking of JP-4, which is similar to commercial Jet B. JP-4 and Jet B have naptha in addition to the kerosene.