Another "Energy Saving" Device

[Eddie Watkins]

Do a search on Brown's Gas. What's your opinion?

Eddie

[Chris Padilla]

Is this a thinly-veiled attempt to discuss flatulence in the OT forum? ;)

:D

Provide a link or two so we can all read the same thing.

[Skip Weiser]

www.brownsgas.com (http://www.brownsgas.com)

[Mike Henderson]

Without reading everything on their site, it appears that the device uses electricity to generate hydrogen and oxygen by electrolysis of water. You can certainly do that, but at a net loss of energy.

If you're somewhere where you can't purchase gas, and electricity won't work for your needs, this would be a solution.

I'm not sure exactly what problem they're trying to solve, however. Maybe you could use it as a way to store solar energy for later use. Anyone else see a use for it?

Mike

[Jerome Hanby]

There is always a net loss whenever you convert one form of energy to another, but you have to ante up in order to get the form you need. What I wonder is what the overall return is using electric current to perform electrolysis versus using the current to charge batteries. It would be interesting to see how many watts you can get back for each kilowatt you expend "charging". If it's even close, looks like using hydrogen would be more economical and less harmful (what do you do with all of those worn out batteries and their innards?).

[Mike Henderson]

There is always a net loss whenever you convert one form of energy to another, but you have to ante up in order to get the form you need. What I wonder is what the overall return is using electric current to perform electrolysis versus using the current to charge batteries. It would be interesting to see how many watts you can get back for each kilowatt you expend "charging". If it's even close, looks like using hydrogen would be more economical and less harmful (what do you do with all of those worn out batteries and their innards?).
The problem I see with any flammable gas is the storage space required (the gas takes a lot more space than the water). You have to compress it, which takes energy, and there's always a danger in compressed flammable gas.

Also, when you go to use the energy, an electric motor can easily be 90% efficient, but almost any internal combustion engine is only about 25% efficient.

As you point out there is a disposal or recycle problem with batteries but I would guess that batteries and electric motors will provide much greater efficiency than converting the electricity to hydrogen and oxygen gas to burn in an internal combustion engine.

Mike

[Jerome Hanby]

Guess I should have stated outright, I'm talking about converting H2 and O2 back into electricity and running an electric motor, not burning them in an IC. Electric versus IC is like comparing apples and oranges in this context. Sort of like who's the better baseball player, Godzilla or King Kong. Personally, I'd bet Godzilla since he's Japanese.


The problem I see with any flammable gas is the storage space required (the gas takes a lot more space than the water). You have to compress it, which takes energy, and there's always a danger in compressed flammable gas.

Also, when you go to use the energy, an electric motor can easily be 90% efficient, but almost any internal combustion engine is only about 25% efficient.

As you point out there is a disposal or recycle problem with batteries but I would guess that batteries and electric motors will provide much greater efficiency than converting the electricity to hydrogen and oxygen gas to burn in an internal combustion engine.

Mike

[Mike Henderson]

Guess I should have stated outright, I'm talking about converting H2 and O2 back into electricity and running an electric motor, not burning them in an IC. Electric versus IC is like comparing apples and oranges in this context. Sort of like who's the better baseball player, Godzilla or King Kong. Personally, I'd bet Godzilla since he's Japanese.
I assume you would convert the hydrogen and oxygen back to electricity in a fuel cell. While different fuel cells have different efficiency ratings, a reasonable value might be 50% efficient.

According to wikipedia, a lead acid battery is between 70% to 92% efficient (charging to discharging) while a lithium ion battery is 99% efficient.

It would be interesting to compute the overall efficiency of putting electricity into a battery, then running a motor - compared to using that electricity to generate hydrogen and oxygen, to compress the hydrogen and oxygen for storage, then to use it in a fuel cell which would then drive an electric motor.

Mike

I did a bit more research on electrolysis. It appears that a reasonable efficiency value for the energy conversion of water to hydrogen and oxygen is 80%. So let's look at the net energy output from each system. Let's assume we start with 100 units of energy in the form of electricity.

For a battery system, let's assume we use an 80% battery, so after storage, we have 80 units of electricity to drive a motor. If that motor is 90% efficient, the output of mechanical energy is 72 units.

For the hydrogen and oxygen system, after conversion of the electricity to hydrogen and oxygen we have 80 units of energy. Let's ignore the energy loss for compressing the gas for storage. If we then put the hydrogen and oxygen into a fuel cell at 50% efficiency, we will get 40 units of energy out of the fuel cell. Using that to drive a 90% efficient motor gives us 36 units of mechanical energy.

So the battery system is much more efficient, even ignoring the energy lost to compress the gases.

[Daniel Savard]

Producing hydrogen from water isn't the best way to do it. The chemical bonds requires more energy to break than producing hydrogen from fossils fuels.

It will cost 50 kilowatt-hours of electricity to produce 1 kg of hydrogen from electrolysis process.

[Jerome Hanby]

Kinda depends on your criteria for "best". You can produce a tremendous amount of electricity for electrolysis with a nuclear power plant and have almost zero carbon left over. From Fossil fuels, lots of carbon, some sulfur, and assorted not too useful compounds.


Producing hydrogen from water isn't the best way to do it. The chemical bonds requires more energy to break than producing hydrogen from fossils fuels.

It will cost 50 kilowatt-hours of electricity to produce 1 kg of hydrogen from electrolysis process.