The efficiencies of Hydrogen

[tcp71]

Every since Ballard Energy started Hydrogen fuel cell work in 1979 we have been hearing about the use of hydrogen as a clean fuel. Since that hasn't happened yet, here is an explanation about hydrogen production and use:

Hydrogen as a vehiclular fuel.

 

[CT8]

I am waiting for the hydrogen revolution .

 

[billt460]

It will never happen. Hydrogen takes more energy to produce than it makes.

 

[StevieC]

It will happen we are still figuring out the logistics, we are close but not quite there yet.

 

[kschachn]

Originally Posted By: StevieC
It will happen we are still figuring out the logistics, we are close but not quite there yet.

No, we are not close. In terms of energy density one would be hard pressed to chose a fuel that's worse than hydrogen. Plus where are you getting it from? You don't just drill a hole in the ground and it comes out like methane. You have to "manufacture" it somehow which immediately puts it on an unfavorable thermodynamic pathway as compared to something that you just extract from the earth.

All of which is separate from the issues hydrogen has for storage and distribution which are significant. You're really a lot better off just utilizing natural gas if you're really bent on using a gaseous fuel (which is a challenge in and of itself for motor vehicles).

 

[sloinker]

The key for use of hydrogen would be an efficient way to extract it from water. Need an alchemist for this. We use hydrogen in our generators at work for cooling. I believe it is also critical in refining processes as a selective catalyst in oil/chemical manufacture. Would be nice if it would become another leg in energy production as coal is phased out.

 

[kschachn]

Originally Posted By: sloinker
The key for use of hydrogen would be an efficient way to extract it from water. Need an alchemist for this. We use hydrogen in our generators at work for cooling. I believe it is also critical in refining processes as a selective catalyst in oil/chemical manufacture. Would be nice if it would become another leg in energy production as coal is phased out.

Yeah getting it from water is just about the worst, oxides are stable compounds and it's going to take a lot of energy to break those bonds no matter what. Some of the stuff that's been posted here before shows that obtaining it from methane is more viable but still thermodynamically costly - especially when compared to just burning the methane directly.

There's a source of unlimited hydrogen only 93 million miles away, all we need is a long pipeline.

 

[Shannow]

Originally Posted By: StevieC
It will happen we are still figuring out the logistics, we are close but not quite there yet.


Probably further away I reckon.

Using renewables at 25% efficiency and 30% capacity factor means that we would need many, many time the nampelate rating of (lets say nukes) to generate "green" hydrogen...then there's the conversion efficiency of hydrogen, throwing the process efficiency down the toilet.

Would direct conversion of fossil fuels be considered "green" ?
Japan is looking at turning Australian brown coal directly to Hydrogen as part of their hydrogen economy.

http://www.abc.net.au/news/2018-04-12/coal-to-hydrogen-trial-for-latrobe-valley/9643570

So yes, they'll have one, but will it be really as the advocates are telling us the future of hydrogen is in terms of "pure water vapour" as the only emission ?

Definitely not...on renewables, it will take massive land use and resources for a nett energy negative. On fossil fuels, or clean nukes, why not just go batteries ?

 

[Dave1027]

Originally Posted By: billt460
It will never happen. Hydrogen takes more energy to produce than it makes.


It can be a lot cheaper if you use solar power to extract it from water.

 

[OVERKILL]

Originally Posted By: Dave1027
Originally Posted By: billt460
It will never happen. Hydrogen takes more energy to produce than it makes.


It can be a lot cheaper if you use solar power to extract it from water.



Electrolysis is not efficient, as already covered above. There are far better ways of extracting hydrogen if that's the end game, that have significantly higher yields and most of them involve nukes.

On the topic of doubling the efficiency of electrolysis, which is covered here: https://phys.org/news/2016-03-efficiency-electrolysis.html

Quote:
Only four per cent of all hydrogen produced worldwide are the result of water electrolysis. As the electrodes used in the process are not efficient enough, large-scale application is not profitable. "To date, hydrogen has been mainly obtained from fossil fuels, with large CO2 volumes being released in the process," says Wolfgang Schuhmann. "If we succeeded in obtaining hydrogen by using electrolysis instead, it would be a huge step towards climate-friendly energy conversion. For this purpose, we could utilise surplus electricity, for example generated by wind power."


And from the Wiki on hydrogen production:
Originally Posted By: Wikipedia
Efficiency of modern hydrogen generators is measured by energy consumed per standard volume of hydrogen (MJ/m3), assuming standard temperature and pressure of the H2. The lower the energy used by a generator, the higher would be its efficiency; a 100%-efficient electrolyser would consume 39.4 kilowatt-hours per kilogram (142 MJ/kg) of hydrogen,[20] 12,749 joules per litre (12.75 MJ/m3). Practical electrolysis (using a rotating electrolyser at 15 bar pressure) may consume 50 kilowatt-hours per kilogram (180 MJ/kg), and a further 15 kilowatt-hours (54 MJ) if the hydrogen is compressed for use in hydrogen cars


So 65kWh per kg of hydrogen produced for automotive fuel let's say. 1kg of hydrogen is 14L/3.73 gallons. To fill a 30 gallon tank then, you'd be looking at 523kWh, which is almost my entire month's hydro usage.

 

[Uphill_Both_Ways]

Shell opened a Vancouver, B.C., hydrogen station in June of 2018. There's nothing about the cost at the pump; it's a bit of a puff piece.

https://www.cbc.ca/news/canada/british-columbia/hydrogen-fuel-pump-opens-in-vancouver-1.4709016

 

[redbone3]

For the money Methane is the most efficient, relatively green fuel. Assume a electric generating plant uses methane (pretty common) to generate electricity, sends it to your battery operated car via wires and transformers, you use an inverter to convert from AC to DC, you have to lose at least 20% of the energy. Burn the methane in your car and that lost 20% goes away. Compared to a hydrogen powered car the methane is much better--the hydrogen is produced from methane and at least 40% of the energy is lost, plus hydrogen has much less power potential per mole so the methane will produce more power from the same sort of storage tank on your car. Most people don't consider the fact that electricity is not a source of energy. You can't dig a hole and mine it. It is produced from an actual source of energy and is only a means of transferring that energy. So, your electric car is using energy that generally requires burning some hydrocarbon. Not as green as you would think. The reason the manufacturers are betting on electric cars is that it really isn't a bet on fuel source. Any fuel source can produce electricity.

 

[oil_film_movies]

Originally Posted By: redbone3
For the money Methane is the most efficient, relatively green fuel.
IF they can solve the problem of leaking methane gas at the wells (powerful greenhouse gas it is...), then it would be green. When you found out how much of it leaks, you wonder if its worth it.
https://www.forbes.com/sites/kensilverst...-sitting-still/

When Budweiser (beer and gas H2 experts) decided to launch 800 H2 trucks, I wondered if they had gone crazy.
https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4799072/1/Budweiser's_New_800-fleet_H2_S
Originally Posted By: oil_film_movies
Bud might not be crazy after all: What could save the H2 approach is dendritic core-shell nickel-iron-copper metal/metal oxide electrodes for efficient electrocatalytic water oxidation, obviously, right??!!
..... I don't know why I didn't think of that before. Actually, I do know why it didn't occur to me, & its probably because I have no idea what that freakin' is!!! Anyway, translated: There might be an easier way to get hydrogen out of water than the current old ways of electolysis or yanking it away from CH4 (methane), too energy intensive there.
https://www.sciencedaily.com/releases/2018/03/180305093708.htm
https://www.sciencedaily.com/releases/2018/04/180410103512.htm
https://www.sciencedaily.com/releases/2018/02/180201141512.htm
etc.

 

[Donald]

Convert hydrogen to helium and in doing so a lot of energy will be produced. Just look at the sun.

 

[97prizm]

Talk with a physicist. You can't change the laws of hydrogen. It's not energy dense, is very light and hangs out in the upper atmosphere. why hydrogen vehicles don't work

 

[Shannow]

Originally Posted By: 97prizm
Talk with a physicist. You can't change the laws of hydrogen. It's not energy dense, is very light and hangs out in the upper atmosphere. why hydrogen vehicles don't work


I built and commissioned (not designed) an electrolytic plant in 1993 to feed the power station generators.

Went back into it on first engineering principals with all the curves available for the Knowles Cells that we installed, KW input, and H2 output...it was an interesting rabbit hole, and scared me given all the hype back in the day for H2 powered cars.

Energy density, and leakage are phenomenol issues to deal with.

 

[PandaBear]

Hydrogen fuel cell was only proposed back in the days because it is not a thermal engine, and therefore in theory gives you near 90% efficiency.

Except the hydrogen "generation" part, so most stationary fuel cell are SOFC that uses natural gas as fuel instead of hydrogen, and then the efficiency goes way down to near combine cycle gas turbine. With the exotic material and construction cost, it end up no cheaper or more efficient than CCGT. Anyone remember Bloom energy? I don't think they are doing well these days, when cheap solar, wind, and batteries came online due to over investment from low interest rate.

The best investment these days is power grid across large areas to dilute the sporadic generation of solar and wind, even better if across many timezone.

Another would be ice storage for refrigeration / air conditioning to shift generation and consumption.

 

[UncleDave]

The efficiency expense to get it into a car under pressure to then convert it back to usable energy to run the car is ludicrous compared to just charging a battery.

Musk on Hydrogen

“Hydrogen is an energy storage mechanism. It is not a source of energy. So you have to get that hydrogen from somewhere. if you get that hydrogen from water, so you’re splitting H20, electrolysis is extremely inefficient as an energy process…. if you say took a solar panel and use the energy from that to just charge a battery pack directly, compared to try to split water, take the hydrogen, dump the oxygen, compress the hydrogen to an extremely high pressure (or liquefy it) and then put it in a car and run a fuel-cell, it is about half the efficiency, it’s terrible. Why would you do that? It makes no sense,”

 

[kschachn]

Originally Posted By: Donald
Convert hydrogen to helium and in doing so a lot of energy will be produced. Just look at the sun.

Sure thing but he devil is in the details.

Kind of like changing U235 into Pb but a lot more difficult.

 

[SubieRubyRoo]

Originally Posted By: kschachn
There's a source of unlimited hydrogen only 93 million miles away, all we need is a long pipeline.


Might be some upcoming projects for that, considering...