Why Can't Fuel Cells Simply Use Water to Generate Hydrogen?

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Discussion Overview

The discussion revolves around the feasibility of using water as a direct source for hydrogen in fuel cells, particularly exploring the processes of electrolysis and energy efficiency. Participants examine the theoretical underpinnings of fuel cells and the practical challenges associated with hydrogen production from water.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why fuel cells cannot directly utilize water to separate hydrogen and electrons, suggesting a cyclical process of borrowing and returning electrons.
  • Another participant points out that using a battery to electrolyze water would involve energy losses, which are typically greater than the net output, raising concerns about efficiency.
  • Several participants reiterate the chemical reactions involved in splitting water and burning hydrogen, noting that while the energy in both processes is theoretically equal, the energy required to split water exceeds the usable energy from burning hydrogen.
  • A participant emphasizes the challenge of sourcing the energy needed for electrolysis, highlighting the dependency on external energy inputs.

Areas of Agreement / Disagreement

Participants express differing views on the practicality and efficiency of using water in fuel cells, with no consensus reached on the feasibility of the proposed processes or the implications of energy losses.

Contextual Notes

Participants acknowledge the energy losses in various stages of the processes discussed, including in power plants, chemical reactors, and during hydrogen combustion, but do not resolve the implications of these losses on overall efficiency.

Who May Find This Useful

This discussion may be of interest to those exploring alternative energy sources, fuel cell technology, and the principles of electrolysis and energy conversion.

Red Ninja
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I was wondering if you could recommend an article that would explain a concept to me. That is: the drawback of fuel cells, reportedly, is that hydrogen is not readily available. However, I am wondering why it is that if the original idea of fuel cells came from reversing the concept that hydrogen could be separated from water, why can't fuel cells take water, separate the hydrogen, separate the electrons and then merge them all back together at the other end of the circuit? Basically borrowing the hydrogen electrons for a minute and then returning them back to the water?
 
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Why not take a battery, use electricity from it and then return it back to the battery? There are always losses in a system, usually larger than the net output.

If you search around a bit, there have been a few good threads about this in the last couple months with a few links to good websites. Would be worth the effort to search this forum a bit.

Cliff
 
Red Ninja said:
However, I am wondering why it is that if the original idea of fuel cells came from reversing the concept that hydrogen could be separated from water, why can't fuel cells take water, separate the hydrogen, separate the electrons and then merge them all back together at the other end of the circuit? Basically borrowing the hydrogen electrons for a minute and then returning them back to the water?
Splitting water: 2H20+ENERGY->2H2+O2

Burning hydrogen: 2H2+O2->2H2O+ENERGY

As you can see, the reactions are mirror images of each other: the energy is exactly the same in each.
 
russ_watters said:
Splitting water: 2H20+ENERGY->2H2+O2

Burning hydrogen: 2H2+O2->2H2O+ENERGY

As you can see, the reactions are mirror images of each other: the energy is exactly the same in each.

The energy used to split water is the same to the energy produced in the burning process. But, the total amount of energy NEEDED to split water into hydrogen + oxygen is a lot bigger then the energy can be USED when we burn the hydrogen.

We have losses in the power plant, transmission grid, chemical reactor in which we split the water, etc.

In the other end, there is losses in the burning process etc.
 
You can certainly electrolyze water to produce hydrogen, which can then be used in fuel cells. The problem, of course, is where do you get the energy to electrolyze the water?

- Warren
 

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