Electrolysis and hydrogen give us the tools needed to decarbonise in ways that batteries never can.

For instance steelmaking:

https://fuelcellsworks.com/news/steeling-from-fossil-fuels-austrians-to-power-steel-industry-entirely-on-clean-hydrogen/

The video in the article here also mentions ammonia, production of which is another massive source of emissions at the moment.

There was an Airbus concept of a hydrogen-powered A380 some time ago.  The hydrogen tank ran along the top of the fuselage and was bigger in diameter than the passenger cabin; it made the plane look like it had hydrocephalus.  Can't find that pic now.

There's a reason that hydrogen isn't going anywhere.

https://www.bbc.com/news/science-environment-11707135

Ignoring 8 year old negative reports eagerly seized upon by the prejudiced there are issues in using hydrogen for commercial aircraft as the storage is still weighty and not very compact.

This route may be more realistic in my view:

'Borer has an idea: Make the X-57 a hydrogen fuel cell aircraft that runs on diesel.

"We're going to pitch that as a flight program. And what will be kind of interesting about that is, for the same weight as what we have for batteries on X‑57, we go from 40 minutes of flight to about three and a half hours."

Fuel cells generate electricity to power electric motors, generally with oxygen from the air and compressed hydrogen. The resulting emissions are nothing more than heat and water. But you don't need hydrogen fuel to power a fuel cell—you can use diesel. "You can store diesel fuel on this airplane, and it converts that," Borer says. "It rips the hydrogen off of the diesel fuel." The diesel fuel cell system does end up producing some carbon dioxide, but only about half as much fuel is needed compared to piston engines.'
https://www.popularmechanics.com/flight/a26609/nasa-plane-electric-x-57-maxwell/

That is still for relatively light aircraft, it is being compared to piston not jet planes, and would take a heck of a lot of doing.

What is realistic is fuel cells for ancillary power, which would reduce pollution considerably in taxiing around the airport and so on.

Aeroplanes are about the toughest application imaginable though, but all sorts of things like buses, trucks, trains and cars are perfectly reasonable and are starting deployment right now.

"... for the same weight as what we have for batteries on X‑57, we go from 40 minutes of flight to about three and a half hours."

3.5 hours is on the low side for a piston-engine plane.  The lowly C-152 carries 26 gallons and burns about 6 gph at medium cruise.  You can easily stretch that to 5 hours at economy cruise.

What is realistic is fuel cells for ancillary power, which would reduce pollution considerably in taxiing around the airport and so on.

Indeed, and there have already been powered nosewheels tested, but you'd need to increase the power to handle taxi demands as well as A/C and avionics and the passenger cabin and everything else.

Ignoring 8 year old negative reports eagerly seized upon by the prejudiced

You say this, and then quote NASA proposing the use of diesel in lieu of H2.  Irony.

If HyperLoops are perfected, high speed domestic air travel will be redundant and air travel will be mostly use over the oceans, provided by hybrid aircraft launched to cruise altitude by booster turbines and maintained at cruise speed by hydrogen fuel cells and ducted electric fans.

It's interesting to read where more and more clean power providers have surplus electricity that they must dump or sell at a loss. One such provider is considering pumped water storage behind Hoover dam. Seems to me that creating hydrogen in storage would be a good use of this surplus.

This is about 'green' ammonia. ThyssenKrupp has been making ammonia plants since 1928 and electrolysis equipment since the 1950's primarily for the Uhde Chlorine business. It is a building a demonstration plant in Port Lincoln, South Australia that will be "one of the first ever commercial plants to produce CO2-free 'green' ammonia from intermittent renewable resources."

Easyjet have been trialling fuel cell based aircraft taxiing along with other systems such as electric tugs since 2016

I am not sure how they are getting on.
http://sustainableskies.org/fuel-cells-for-taxiing/

Arnold:

I think you are right, and what is going on here is testing hydrogen for annealing etc, rather than at this stage for the power.

After all, we pretty well know the process to do the later, even though we have to work on the economics etc, whereas the former needs to be thoroughly tested to ensure it will work in practise before it is deployed at scale.

So it is replacing coal and coke as a test facility.

It looks like they use the oxygen for steel.

Calgarygary:

I found the rate of utilisation of the electrolysers using surplus renewables difficult to understand too, at any reasonable cost.

It seems though that they reckon that costs are reducing fast enough to make it viable though.

They are helped somewhat by wind and solar peaking in an unrelated manner.

IMO though it seems more likely that since hydrogen is transportable it would be produced largely where land is very cheap and there is loads of sun.

And for nuclear fans, yep, I would still like to use that for baseload but I don't waste too much time mourning what is not happening.

Instead I try to figure out what is viable with what is going on.

Trying to understand the "green" steel-making angle came upon several relevant references :

"I wonder, what do they need it for? What is the application of ammonia in steel industry - what processes of making or processing steel require this much ammonia?
"Likely, for nitriding http://en.wikipedia.org/wiki/Nitriding . Essentially, ammonia is used as nitrogen donor. Nitrogen atoms diffuse into steel, producing hardened, corrosion-resistant surface layer."
"Indeed - N2 will not nitride steel in a thermal process. NH3 breaks up much more easily, so that is used"...........

"Hydrogen is produced by dissociation of ammonia at about 982 deg C with the aid of a catalyst – which results in a mix of 75 % hydrogen and 25 % mononuclear nitrogen (N rather than N2). The mix is used as a protective atmosphere for applications during bright annealing of cold rolled coils and strips. Hydrogen is also used as a reducing agent in the manufacture of iron.

Hydrogen is mixed with inert gases to obtain a reducing atmosphere, which is required for many applications in the steel industry, such as in laboratories, heat treating steel and welding. It is often used in annealing stainless steel alloys and magnetic steel alloys.

Large quantities of hydrogen are used to purify argon that contains trace amounts of oxygen, using catalytic combination of the oxygen and hydrogen followed by removal of the resulting water."..........

"Hydrogen – used as a reducing agent replacing carbon, as the
reaction produces only water vapour. Hydrogen, either pure or as
a synthesis gas (syngas) through reforming methane or natural
gas, can be used in conventional direct-reduction reactors or
in more futuristic flash reactors. The hydrogen will need to be
produced using carbon-free energy hydro, nuclear, or renewable
for the new processes such as water electrolysis or natural gas
reforming – which require high-pressure steam or carbon-free
electricity - otherwise, it would defeat the purpose as the energy
requirement is higher than using it directly in the steelmaking
process. The energy used in a hydrogen reduction process is
significantly higher than with carbon due to its cooling effect and
may require 4-5 times the energy needed currently. This energy
also needs to be generated from carbon-free sources to avoid
shifting the emissions elsewhere.".........

So many uses.
I was thinking that for electricity or heat production on site production and storage provides a certain autonomy from the grid if reliability were a problem.
The 6MW does not make reference to electricity production - that's my error of assumption.

What is the price per kW or MW for this system?