Ammonia for fuel cells

Ammonia for fuel cells
Traditional fuel cell research involves hydrogen fuel cells, but UD researchers are engineering fuel cells that utilize ammonia, the molecule pictured above, instead. Credit: University of Delaware

Fuel cells are pollution-free power sources that convert chemical energy to electricity with high efficiency and zero emissions. Fuel cell cars, trucks, and buses would allow people to travel long distances with convenient refueling and less of a carbon footprint.

Researchers at the University of Delaware are working on technology to make fuel cells cheaper and more powerful so that vehicles can be a viable option for all someday. Traditional fuel cell research involves hydrogen fuel cells, but the UD researchers are engineering fuel cells that utilize ammonia instead.

In a new analysis published in the journal Joule, a team of engineers at the Center for Catalytic Science and Technology found that among fuels produced from , ammonia has the lowest cost per equivalent gallon of gasoline.

"As a nitrogen-based , ammonia is cheaper to store and distribute than hydrogen and avoids the carbon dioxide emissions of other liquid fuels, which are expensive to capture" said Brian Setzler, one of the lead authors and a postdoctoral associate at UD.

The challenges, however, are that ammonia does not work in a proton exchange membrane fuel cell; and that ammonia is more difficult to oxidize than hydrogen, which causes ammonia fuel cells to produce less power than . The team solved the first problem by using hydroxide exchange membrane fuel cells that have been studied for over a decade in the lab of Yushan Yan, a Distinguished Engineering Professor at UD. Assisted by a $2.5 million grant from the REFUEL program of the Advanced Research Projects Agency-Energy (ARPA-E) in the U.S. Department of Energy, the UD team engineered a fuel cell membrane that can operate at higher temperatures to speed up ammonia oxidation. They also identified catalysts that were not poisoned by ammonia.

"With these improvements, we have demonstrated a new direct ammonia fuel cell prototype with a peak power density of 135 milliwatts per square centimeter, which closes much of the performance gap compared to hydrogen," said research associate Yun Zhao, the lead author of the paper who has been working on direct ammonia fuel cells since 2016.


Explore further

Minimizing ammonia fuel emissions

More information: Yun Zhao et al. An Efficient Direct Ammonia Fuel Cell for Affordable Carbon-Neutral Transportation, Joule (2019). DOI: 10.1016/j.joule.2019.07.005
Journal information: Joule

Citation: Ammonia for fuel cells (2019, August 15) retrieved 17 September 2019 from https://phys.org/news/2019-08-ammonia-fuel-cells.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
128 shares

Feedback to editors

User comments

tpb
Aug 15, 2019
Ammonia is highly toxic and the fumes will cause respiratory problems, eye problems etc.
Ammonia was one of the first refrigerants and is more efficient than the replacements used now.
Ammonia is still used in large commercial refrigerators and freezers, but not in homes or cars because of the danger from a leak.
I can't see using ammonia as a fuel in a fuel cell powered vehicle.

Aug 15, 2019
And the gas stations would smell like a horse stable...

Aug 15, 2019
Ammonia is highly toxic and the fumes will cause respiratory problems, eye problems etc.
Ammonia was one of the first refrigerants and is more efficient than the replacements used now.
Ammonia is still used in large commercial refrigerators and freezers, but not in homes or cars because of the danger from a leak.
I can't see using ammonia as a fuel in a fuel cell powered vehicle.


yet not for any of those reasons you listed.

ammonia is largely made from petroleum. it is a decent way to transport hydrogen. but not as good as natural gas (for which we already have a large permanent infrastructure/transport system. no need to reinvent the wheel).

Aug 15, 2019
...
I can't see using ammonia as a fuel in a fuel cell powered vehicle.

yet not for any of those reasons you listed.
ammonia is largely made from petroleum.

Hunh?!? How is that done? What process do they use to replace the carbon atoms with Nitrogen ones?
it is a decent way to transport hydrogen. but not as good as natural gas (for which we already have a large permanent infrastructure/transport system. no need to reinvent the wheel).

Well, ammonia IS less prone to igniting when you light that mat-

Aug 15, 2019
Ammonia is also a byproduct of sweat glands. Bacteria gravitate to Ammonia and utilise/consume it as fuel, removing the odor of Ammonia from skin. It was found that horses sweating are exuding Ammonia, which is one of the reasons why they roll around on their back in dirt that contains bacteria. The bacteria is picked up by the horses and the bacteria consume the Ammonia, thus eliminating the Ammonia smell from the horses.
There are humans who also have discovered this process and have stopped using soap/body wash in their daily shower. When they sweat, they produce Ammonia, which is consumed by the beneficial bacteria on their skin. The goal is to keep the bacteria on skin to consume the Ammonia and that eliminates the odor from sweating. Showering just washes away most dirt and grime but doesn't kill the bacteria itself that would be washed away and killed by the use of soap/body wash.
It's an interesting concept, so more and more humans have decided to try it.

tpb
Aug 15, 2019
Shootist,
Ammonia toxicity
https://www.atsdr...mp;tid=2

Aug 16, 2019
What process do they use to replace the carbon atoms with Nitrogen ones?


The Haber process. Hydrogen is separated from natural gas using heat from burning natural gas, and then combined with nitrogen under high pressure.

The goal is to keep the bacteria on skin to consume the Ammonia and that eliminates the odor from sweating


Not really, they just get so used to the smell that they stop recognizing it - kinda like people who own cats, whose whole apartment reeks of ammonia from the litter box.

Aug 16, 2019
ammonia is largely made from petroleum. it is a decent way to transport hydrogen. but not as good as natural gas


The reason why they have to propose hydrogen, ammonia, formic acid, etc. as fuels is because governments and regulators everywhere have outlawed emissions of CO2 regardless of the carbon source. If the vehicle emits CO2 from the tailpipe, it is subject to strict regulations such as <95 g-CO2/km in the EU after 2021, equivalent to about 4.1L/100km or about 70 MPG which limits the size, weight, power of the vehicle and makes it non-competitive against battery electric vehicles, which in most places are subsidized or even tax-exempt.

So what happens there is, fuel cell cars are being killed by environmental regulations before they can even enter the market. There's no point in developing them because you're not allowed to use them to any effect, or you have to use such difficult fuels that nobody will actually want them anyhow.

Aug 16, 2019
So even if you feed food scraps and solar power to a vat of bacteria to make you methane - if you put that in your car, it produces CO2, which means it has to go by the emissions limits and fuel economy standards that essentially dictate how much of the fuel you can use per mile of travel.

And already we're at a point where the regulations - if strictly and honestly adhered to - would produce cars that are simply two bicycles welded side by side with a moped engine for a power source. All the manufacturers get around it by lying about the true fuel consumption ("MPG gap").

Having a fuel cell would improve the situation a little by its higher efficiency, but still you couldn't build a proper family car, a truck or a SUV, because you have to go that 70 miles on a gallon equivalent and real world physics limits you to about 40-50 MPG.


Aug 16, 2019
Mind: 55 MPG UK is 45 MPG US. Different gallon.

Then, if you actually do produce a fuel cell vehicle that burns hydrocarbon fuels, and manages to average 70 MPG as per regulations... don't worry, by 2031 it has to do 100 MPG because apparently physics is up to vote.

Aug 16, 2019
"....with high efficiency...."
High efficiency compared to what?
The efficiency of a fuel cell is approx. 60 %. That is not very efficient compared to a SOA-Liion battery; it is, however, more efficient than an ICE. Additionally, a fuel cell is far more EXPENSIVE than a battery.


Aug 16, 2019
Ammonia is also a byproduct of sweat glands. Bacteria gravitate to Ammonia and utilise/consume it as fuel, removing the odor of Ammonia from skin. It was found that horses sweating are exuding Ammonia, which is one of the reasons why they roll around on their back in dirt that contains bacteria. The bacteria is picked up by the horses and the bacteria consume the Ammonia, thus eliminating the Ammonia smell from the horses.
T...

The majority of it is released via urine. If YOU smell like ammonia by sweating, there's something wrong with your system...

Aug 16, 2019
What process do they use to replace the carbon atoms with Nitrogen ones?


The Haber process. Hydrogen is separated from natural gas using heat from burning natural gas, and then combined with nitrogen under high pressure.

Sounds like they release CO2 in the burning...
Doesn't sound very "green" OR efficient...

Aug 16, 2019
Additionally, a fuel cell is far more EXPENSIVE than a battery.


Not really. According to the DoE, $55/kW is attainable with present technology in volume production. That makes a car engine cost around $6,000 which would buy you enough battery cells (but not the assembled battery) of a Nissan Leaf.

Aug 17, 2019
What process do they use to replace the carbon atoms with Nitrogen ones?


The Haber process. Hydrogen is separated from natural gas using heat from burning natural gas, and then combined with nitrogen under high pressure.

Sounds like they release CO2 in the burning...
Doesn't sound very "green" OR efficient...


It's not too bad - it's a closed loop process that recycles most of the heat. 5% of the world's natural gas consumption goes towards making ammonia, which then produces the fertilizers that grow 80% of our food crops.

Aug 17, 2019
"Not really. According to the DoE, ..."
I'm referring to "state of the art" technology. Presently, a 100 kWh FC costs approx. $75,000.00. A complete BEV with a 100 kWh Battery starts at $50 - $60 thousand. In the future, FC prices may drop but so will battery prices. The ratio will remain.

Aug 17, 2019
What process do they use to replace the carbon atoms with Nitrogen ones?


The Haber process. Hydrogen is separated from natural gas using heat from burning natural gas, and then combined with nitrogen under high pressure.

The goal is to keep the bacteria on skin to consume the Ammonia and that eliminates the odor from sweating


Not really, they just get so used to the smell that they stop recognizing it - kinda like people who own cats, whose whole apartment reeks of ammonia from the litter box.[/qsays Eikka

Daily showering should eliminate the Ammonia smell on humans. Excessive sweating would need more than one shower daily. It depends on how active the human is, on a daily basis. On horses that aren't allowed to roll around in the dirt but are washed frequently, they will smell of Ammonia.
Cats are very clean animals, but they also need a cleaned up cat box or they will pee and defecate on a clean floor to avoid going in the smelly litter box.

Aug 17, 2019
so ammonia is cheap but it doesn't work. Why not just do a story on using dirt, or sea water?

Aug 23, 2019
In the future, FC prices may drop but so will battery prices. The ratio will remain.


Unlikely. Batteries will experience material shortages, because the mining industry can't scale up fast enough to meet the demand. With all the potential uses and demands for lithium batteries, the industry would have to scale more than 1000x in a few short years. What happens is, any price drop will be met with an expansion in demand, which largely cancels the price drop because they can't make enough batteries. The insult to injury is that recycling batteries currently costs about 3-4x the price of virgin materials.

Meanwhile, fuel cells can be made using far less materials, and the main reason they're expensive now is because nobody's making them in large-enough volumes. That's the point of the DoE study as well.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more