Powerline electrolysis hydrogen production

[artis]

Hydrogen production consumes a lot of energy because one is running current through water in order to produce hydrogen.
Why can't we use current that already runs in powerlines for example like HVDC and create a series electrolysis apparatus.

Water electrolysis needs a minimum voltage difference of about 1.5 volts, so in theory making the HVDC + wire instead a hollow pipe conductor with water in the middle would generate such a voltage drop across some distance of wire easily. So could we in theory have a HVDC transmission line that is also a electrolysis system producing hydrogen along the way.

The current runs in the line nevertheless why not use some of it?

 

[Baluncore]

Because a series electrolysis cell would consume power and drop the line voltage for all consumers. The electrolysis cell would have to operate at the varying current used by the consumers.
Electrolysis is inefficient.

 

[Bystander]

NO free lunch.

 

[artis]

NO free lunch.

I never meant it would be free lunch , all I was implying is that it seems to be more efficient to use current meant for other loads to produce hydrogen through electrolysis than to simply additionally use a power supply to do so , but this is more of a theory question as practically I can understand creaing the infrastructure for this would be far costlier than to do it at a specific location.

I read this has been proposed as possible energy "battery" for renewables as hydrogen can be stored easily and used upon need.

 

[anorlunda]

all I was implying is that it seems to be more efficient to use current meant for other loads to

That would be a free lunch. Using the current without affecting the efficiency of the power grid.

 

[Borek]

current meant for other loads

Basically you are saying that putting a load consisting of electrolytic cells in series with other loads will make it miraculously disappear.

 

[hutchphd]

but this is more of a theory question

Yes and you are confused. By your logic we could just turn the voltage down at the power station and save energy. Power is volts times current and
there is indeed no free lunch.
I once had a boss who was convinced that we could double the battery life of our product by putting the two batteries in parallel instead of series. He was exceptional shall we say.

 

[Vanadium 50]

I once had a boss who was convinced that we could double the battery life of our product by putting the two batteries in parallel instead of series.

I bet he's the CEO now!

 

[artis]

ahh forget it folks, my idea wasn't free lunch I mean judging by my answers here in other posts I should know better than to think that one can produce electrolysis without power consumption.

 

[Baluncore]

So could we in theory have a HVDC transmission line that is also a electrolysis system producing hydrogen along the way.

Yes. But what advantage is there in the generation of mixed H2 and O2 distributed over the grid. How could the gasses be separated and bulked up for transport to a site where it might be used to regenerate electrical energy, or to fuel vehicles?

 

[Rive]

If I take it right, the idea would be about eliminating the conversion loss (power supply loss of feeding the electrolyser) through utilising the current on a transmission DC-link?

I don't think it would be a good idea to mix functions, but more importantly: industrial scale electrolysers are stacks, not cells: with input voltage up to few hundred volts => likely 90+% conversion efficiency. So not much to gain there, for the price of messing up a (really) high voltage DC environment.

 

[artis]

If I take it right, the idea would be about eliminating the conversion loss (power supply loss of feeding the electrolyser) through utilising the current on a transmission DC-link?

Yes that was the idea but as I said myself and you including it's not feasible.