Solar, Wind Renewable Energy

[NW-Bound]

Europe is going big on hydrogen with the H2Med project. A BarMar undersea pipeline between Barcelona and Marseille will transport 2 million tonnes of hydrogen a year.

This hydrogen will be generated by electrolysis with solar energy from Spain and Portugal.

See: https://www.thelocal.es/20221210/hydrogen-pipeline-between-spain-and-france-to-be-ready-by-2030/

 

[misanman]

A BarMar undersea pipeline between Barcelona and Marseille will transport 2 million tonnes of hydrogen a year.

Just curious, how do you weigh hydrogen?

 

[Gumby]

Just curious, how do you weigh hydrogen?

I would imagine you would weigh an empty flask, fill it with hydrogen and weigh it again. The net is the weight of the hydrogen.

 

[Alan]

Glasgow has a green hydrogen project underway as well.

https://itm-power.com/projects/gree...cility aims to supply,and back again each day.

The funding will be used for a 10MW electrolyser and associated four tonnes of storage in what is the first phase of development for ScottishPower’s 20MW Whitelee Windfarm hydrogen production and storage facility to be sited near Glasgow. The facility aims to supply green hydrogen made from wind power to the commercial market by the end of 2023. When operational, it will be capable of producing up to eight tonnes of green hydrogen a day. That’s equivalent to fuelling over 550 buses to travel from Glasgow to Edinburgh and back again each day.

The project is designed to provide carbon-free transport and clean air for communities across the city and wider central belt region, with Glasgow aiming to become the first net-zero city in the UK by 2030.

 

[misanman]

I would imagine you would weigh an empty flask

I think it would need to be empty as in a "complete vacuum". If it had air in it then the air would weigh more than the hydrogen.

 

[braumeister]

I think it would need to be empty as in a "complete vacuum". If it had air in it then the air would weigh more than the hydrogen.

So make it easier. Just cool it down to 20°K and pour it into your previously weighed, evacuated flask.

 

[Gumby]

I think it would need to be empty as in a "complete vacuum". If it had air in it then the air would weigh more than the hydrogen.

But the net change would still be the hydrogen, with or without air. I do this all the time when I make soap. I put an empty bowl on the scale, zero the scale, pour one type of oil in it and read the weight. Then I re-zero the scale and pour another type of oil into the mix and read the weight. The fact that there is already oil in the bowl is irrelevant to the ability to weigh the additional oil.

 

[NW-Bound]

We have talked about how converting PV electricity to hydrogen then back to electricity has a much poorer efficiency than charging up a lithium battery.

However, until batteries get cheaper, it looks like hydrogen is the only means we have for bulk storage and transfer.

 

[Gumby]

We have talked about how converting PV electricity to hydrogen then back to electricity has a much poorer efficiency than charging up a lithium battery.

However, until batteries get cheaper, it looks like hydrogen is the only means we have for bulk storage and transfer.

Hydrogen will be most useful for applications that require higher energy density at lighter weight, like aircraft.

 

[NW-Bound]

But the net change would still be the hydrogen, with or without air. I do this all the time when I make soap. I put an empty bowl on the scale, zero the scale, pour one type of oil in it and read the weight. Then I re-zero the scale and pour another type of oil into the mix and read the weight. The fact that there is already oil in the bowl is irrelevant to the ability to weigh the additional oil.

I beg you to reconsider.

When you pour oil into the bowl, it displaces the air that was there.

When you put hydrogen in a container, does it not also replace the air that was there?

 

[NW-Bound]

Hydrogen will be most useful for applications that require higher energy density at lighter weight, like aircraft.

Hydrogen has a very high energy density, in terms of Joules per pound. However, its volumetric energy density is lousy, because you cannot easily make and store liquefied hydrogen.

Even in liquid form at -423F, a tank of 75 liters (20 gal) holds only 5 kg (11 lbs) of liquid hydrogen. This 5 kg of liquid hydrogen has the energy of 31 kg of gasoline or 8 gallons.

In short, 5 kg of liquid hydrogen = 31 kg of gasoline. Good weight!

But 20 gal of liquid hydrogen = 8 gal of gasoline. Bad volume!

And worse, for practical applications we can only use stored compressed hydrogen. And high-pressure vessels for 10,000 psi weigh alot!

 

[Gumby]

I beg you to reconsider.

When you pour oil into the bowl, it displaces the air that was there.

When you put hydrogen in a container, does it not also replace the air that was there?

No. The preexisting air in the cylinder is compressed, but it remains.

 

[mpeirce]

Glasgow has a green hydrogen project underway as well.

https://itm-power.com/projects/gree...cility aims to supply,and back again each day.

Our local nuclear power station is also a DOE pilot site for “zero-carbon” hydrogen production (most hydrogen is still more cheaply produced from natural gas today). It should start producing hydrogen in quantity next year using electrolysis.

That being said, hydrogen as a fuel for transportation, heating, or heavy industry is still very much in the research realm. Hence the need to have the DOE fund the work. No company is ready to commercialize this stuff.

 

[JoeWras]

Just curious, how do you weigh hydrogen?

Oh, it has been 40+ years, so the memory is fuzzy. We used a device similar to this:

Not exactly that, as you can see, since it has a clamp.

So you bubble the gas you want to weigh up into the tube which had a full water column. As long as the column is forced up by atmospheric pressure, you are OK. (The column can't be too high.)

The gas displaces the water and ends up in the trough. You weigh the whole mess before and after. There's your hydrogen weight.

We created a few different gases this way and did our molar math. This is not precise because the gas can diffuse into water, water evaporates, and blah, blah, blah, but it is good enough for an experiment.

Surprised we don't have more ChemE's on this forum. They could probably talk volumes (pun intended) on the matter.

 

[NW-Bound]

No. The preexisting air in the cylinder is compressed, but it remains.

In that case then yes, the incremental weight that is measured is due to the additional substance that is introduced.

 

[misanman]

The gas displaces the water and ends up in the trough. You weigh the whole mess before and after. There's your hydrogen weight.

Fascinating! Goes to show that there is (almost) no question that someone on this forum can't answer! (Sounds funny - too many negatives?)

 

[NW-Bound]

The gas displaces the water and ends up in the trough. You weigh the whole mess before and after. There's your hydrogen weight...

The scale must have a very good resolution to work.

If you capture 1 quart of hydrogen at atmospheric pressure, that's 83 mg or 0.003 oz of hydrogen.

If the whole apparatus weighs 1 lb or 16 oz before the hydrogen is captured, it weighs 16.003 oz afterwards.

 

[JoeWras]

The scale must have a very good resolution to work.

If you capture 1 quart of hydrogen at atmospheric pressure, that's 83 mg or 0.003 oz of hydrogen.

If the whole apparatus weighs 1 lb or 16 oz before the hydrogen is captured, it weighs 16.003 oz afterwards.

Yes. First of all, the tube was pretty big. Second of all, I think our professor used some fancy scale to "prove" to us the concept.

EDIT: if I recall, it was actually a simple balance scale with one size having calibrated 1g and other side a calibrated 0.99g, and then the experiment is run until it balances with the extra 0.01g of gas? Something like that. This proved the molar volume measurement method.

What we classroom peons did was measure the volume. And through the concepts of molar math, we derived the weight.

 

[NW-Bound]

^^^ If you try to catch more gas to have a larger volume to weigh, then the apparatus gets accordingly larger and heavier. The required resolution of the scale stays the same.

Well, how did the physicists of the 18th-19th centuries measure or weigh anything, without the equipment we now have?

 

[NW-Bound]

I forgot something.

If you capture 1 quart of hydrogen by displacing 1 quart of water, then the water alone is 32 oz. Your scale must see 0.003 oz change in 32 oz, and that does not include the weight of the container.

 

[JoeWras]

^^^ If you try to catch more gas to have a larger volume to weigh, then the apparatus gets accordingly larger and heavier. The required resolution of the scale stays the same.

Well, how did the physicists of the 18th-19th centuries measure or weigh anything, without the equipment we now have?

This was kind of like the supercollider of the day. Weights and measurements were the actual research, and a whole lot of work was done on it. Clock makers were developing fine machining, so naturally some of that could be applied to precision scales.

From this work, much was learned about volume and mass. Right away, the metric system was designed with this in mind. And of course the table of elements was based on molecular weight.

All of this was derived and inferred by super clever methods, like measuring gas volume (which is easy) at a certain temperature and atmosphere.

BTW, if I recall, our experiment took the long tube and we filled with water and acid and inverted it onto a piece of metal which dissolved. I think our lab test was to discover what gase(s) were given off by the volume produced.

It is hazy. I was really into chemistry but after some of this mind numbing computation, I decided to go into computers instead.

One last memory: my stupid lab partner decided to siphon the water out of the trough. Don't ask me why. The water had diluted acid in it. He ended up talking about his "clean teeth" the rest of the semester. Nothing like a little hydrochloridic acid bath to get rid of the plaque.

 

[explanade]

Read that handling hydrogen isn't easy.

For instance, they wouldn't want to use hydrogen in households to power the stove or furnace.

So it's going to be used at some scale, probably at power plants.

 

[Gumby]

...

So it's going to be used at some scale, probably at power plants.

I don't see why you would do that. Producing hydrogen by electrolysis, then turning the hydrogen back into electricity by burning it and spinning a turbine is just inefficient. If you already have sufficient electric power to make the hydrogen, then you have sufficient electric power. The place to use hydrogen is where you can't have an electric power plant. I'm thinking areas like transportation (rail, road, ship or air)

Although, I can envision producing hydrogen as a way to potentially "store" electric power like a battery, if you have temporary excess wind and/or solar generation.

 

[NW-Bound]

It is planned to store solar and wind power via hydrogen generation by electrolysis. The sun does not shine at night, and the wind does not blow 24/7/365.

We don't have cheap enough lithium batteries, and run out of places to build huge reservoirs for pumped hydro storage.

What I found surprising is converting hydrogen back to electricity via burning it in a turbine to spin a generator is about as efficient as feeding it to a hydrogen fuel cell. I thought a fuel cell would be more efficient, but both can be about 50% efficient.

If you are going to use compressed hydrogen in a vehicle, then a fuel cell is used to generate electricity to run an EV. There are production cars made by Honda, Toyota, and Hyundai that work this way.

 

[NW-Bound]

Read that handling hydrogen isn't easy.

For instance, they wouldn't want to use hydrogen in households to power the stove or furnace.

So it's going to be used at some scale, probably at power plants.

There's talk of blending some hydrogen into the nat gas lines to the homes. Not 100% carbon free, but they say it helps in the interim.