Gasoline Fuel Cells: Energy, Weight & Efficiency

In summary: Fuel cells also have a weight advantage over traditional engines, but their efficiency is hindered by contaminants that can damage the mechanisms over time. Additionally, removing hydrogen from gasoline for fuel cell reactions can be difficult and costly. Overall, fuel cells have the potential to be more efficient than internal combustion engines, but there are many factors that can affect their performance and efficiency.
  • #1
bbbl67
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I understand that there is some research going on into gasoline (i.e. petrol) fuel cells (as opposed to the more typical hydrogen or alcohol fuel cells). How much energy can be released through a gasoline fuel cell, as opposed to simply burning it in an internal combustion engine? Will more energy be released or less than combustion? Also how much weight do fuel cell apparatuses usually weigh? Compared to an IC engine of course. Just looking for ballpark figures.

Just wondering if fuel cells would be more practical power sources for electric engines than batteries? And if so, how much efficiency can be expected? The reason I'm asking about gasoline fuel cells is because the infrastructure for gasoline already exists throughout the world. I'm pretty convinced that an electric engine is miles above an IC engine in terms of both performance and efficiency, so having cars driven by electric motors is the way to go from here on in, just it's a matter of whether batteries or fuel cells should be the power source?
 
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  • #2
A fuel cell using a liquid hydrocarbon fuel has a great volume advantage over gaseous fuels. A 20 gallon tank with liquid fuel holds much more energy than 20 gallons of gas at modest pressures.

However, the actual efficiency of a fuel cell depends on many factors and IMO is too difficult to estimate without a lot more detail. A persisting problem in fuel cell design is not efficiency but lifetime. As the cell makes energy, the fuel leaves contaminants behind that foul the mechanisms. You would not be happy with an energy efficient fuel cell car if you had to buy a new fuel cell (costing $10000) every six months.

But try the chemistry yourself. If you removed all the hydrogen from gasoline, what are you left with as a waste product? How would you remove that waste from the cell? Then if you took all that hydrogen and combined it with oxygen in the fuel cell, how much energy is there to capture? When you have that answer, then just divide by 2 or 4 to account for real life imperfections and you have a back-of-the-envelope estimate of the efficiency.
 
  • #3
anorlunda said:
A fuel cell using a liquid hydrocarbon fuel has a great volume advantage over gaseous fuels. A 20 gallon tank with liquid fuel holds much more energy than 20 gallons of gas at modest pressures.

However, the actual efficiency of a fuel cell depends on many factors and IMO is too difficult to estimate without a lot more detail. A persisting problem in fuel cell design is not efficiency but lifetime. As the cell makes energy, the fuel leaves contaminants behind that foul the mechanisms. You would not be happy with an energy efficient fuel cell car if you had to buy a new fuel cell (costing $10000) every six months.

But try the chemistry yourself. If you removed all the hydrogen from gasoline, what are you left with as a waste product? How would you remove that waste from the cell? Then if you took all that hydrogen and combined it with oxygen in the fuel cell, how much energy is there to capture? When you have that answer, then just divide by 2 or 4 to account for real life imperfections and you have a back-of-the-envelope estimate of the efficiency.
One thing I'm lost about is why would you need to remove the hydrogen from the gasoline? Couldn't you do a fuel-cell reaction with the whole molecule of petrol (or diesel, or kerosene, etc.)? I mean you'd end up with the same waste products as a regular air combustion of the fuel (carbon dioxide & water), but hopefully it would be a lot slower reaction, and therefore more efficient than internal combustion?
 
  • #4
https://en.wikipedia.org/wiki/Fuel_cell said:
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  • #5
bbbl67 said:
How much energy can be released through a gasoline fuel cell, as opposed to simply burning it in an internal combustion engine?
Well, gas engines tend to run at about 25% efficiency and have complicated drivetrains. Fuel cells run on the order of 60% efficiency. So figure on around triple the output.
 
  • #6
anorlunda said:
hydrogen fuel cell schematic
Well, sure, that's the case for a hydrogen fuel cell, where just hydrogen and oxygen goes in, and out comes water. But in a gasoline fuel cell you'll have other reactions too, like carbon and oxygen, can't you extract electric potential from those reactions too, and not just the hydrogen and oxygen ones?
 
  • #7
russ_watters said:
Well, gas engines tend to run at about 25% efficiency and have complicated drivetrains. Fuel cells run on the order of 60% efficiency. So figure on around triple the output.
Well, that's why I was asking this question. But there are cases where a certain type of reaction is much more efficient than another type of reaction, yet it produces less power in the end. So would this be the case with a fuel cell vs. internal combustion engine? For example, in an IC engine, it's harnessing the heat energy of the fuel reaction. But in a FC, it's harnessing the movement of electrons. Is heat a more abundant source of energy than electrical potential in these reactions?
 
  • #8
bbbl67 said:
from those reactions too,
"Air-garbage" fuel cells are possible in principle; the practice is another matter. The carbon oxidation is also described as a hydrogen reformer/steam reformer https://en.wikipedia.org/wiki/Steam_reforming .
 
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  • #9
Bystander said:
"Air-garbage" fuel cells are possible in principle; the practice is another matter. The carbon oxidation is also described as a hydrogen reformer/steam reformer https://en.wikipedia.org/wiki/Steam_reforming .
Can this be put into an ordinary sized passenger vehicle, or is this something that belongs in an industrial-scale refinery plant situation?
 
  • #10
It's industrial scale;
russ_watters said:
60% efficiency. So figure on around triple the output.
... , and divide by three for the hydrogen/steam reformer, and you're back to square one. Very attractive at first glance, and break-even at best when examined in detail.
 
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  • #11
bbbl67 said:
Well, sure, that's the case for a hydrogen fuel cell, where just hydrogen and oxygen goes in, and out comes water. But in a gasoline fuel cell you'll have other reactions too, like carbon and oxygen, can't you extract electric potential from those reactions too, and not just the hydrogen and oxygen ones?

It's not impossible, but I haven't heard of any such fuel cell designs.

You have to consider the end products too. With a hydrogen cell, H combines with O to produce H2O (water) which can be drained onto the road. With other reactions, the end product might not be liquid or it may be polluting or toxic which means you would also need to carry a additional tank to hold the waste products. You also need a way to dispose of those wastes eventually.

I repeat what I said earlier, factors other than efficiency can dominate fuel cell practicality.
 

1. What is a gasoline fuel cell?

A gasoline fuel cell is a type of electrochemical cell that generates electricity by converting the chemical energy of gasoline into electrical energy. It works by combining gasoline with oxygen from the air to produce a chemical reaction that creates electricity, water, and carbon dioxide as byproducts.

2. How does a gasoline fuel cell work?

A gasoline fuel cell works by using a catalyst to split gasoline into hydrogen and carbon monoxide. The hydrogen is then exposed to a negatively charged electrode, where it releases electrons and becomes a positively charged ion. The electrons flow through an external circuit, creating an electrical current, while the positively charged ions travel to a positively charged electrode and combine with oxygen from the air, producing water and carbon dioxide.

3. What are the advantages of using gasoline fuel cells?

Gasoline fuel cells have several advantages, including high energy density, fast refueling times, and low emissions. They also have a longer lifespan compared to traditional batteries and can be used in a wide range of applications, from powering vehicles to providing backup power for buildings.

4. What is the weight and efficiency of gasoline fuel cells?

The weight and efficiency of gasoline fuel cells can vary depending on the specific design and application. However, on average, they have a weight-to-power ratio of around 40-50 watts per kilogram and an efficiency of 30-40%, meaning they can convert 30-40% of the energy in gasoline into electrical energy.

5. What are the current limitations of gasoline fuel cells?

Some of the current limitations of gasoline fuel cells include high production costs, the need for a steady supply of gasoline, and the potential for carbon monoxide poisoning if not properly managed. There are also challenges in developing efficient and cost-effective methods for storing and transporting gasoline for use in fuel cells.

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