[XorNot]

You absolutely could lay a cable that long, and IMO we should. There is no reason not to export abundant renewable energy today while we can, and figure out the long term storage issues as we go.

Hydrogen can be manufactured anywhere you have seawater and electricity, so it would be a much better use of resources to lay a subsea superconducting cable once and let Japan store power by generating hydrogen locally.

[credit_guy]

One large LNG carrier of class Q-Max carries 260000 m3 of liquefied gas. If we stitch to hydrogen, that contains 2.2 million gigajoules of energy, which is 614 GWh, or a bit more than 25 GWd. If we assume a conversion efficiency of 60%, then that's about 15 GWd of electricity after taking into account all the losses. If one carrier arrives every 15 days, then this can produce a sustained 1 GW of electricity, which is about the same as a full size nuclear reactor. The transit from Australia to Japan takes about 30 days, so it would take 4 carriers to arrange for 1 to reach Japan once every 15 days. Such a carrier costs about $200 MM, so you get to invest about $1 BN to get a sustained 1GW of electricity in Japan.

How does this compare to submarine power cables? [1] is an example of a 1200 km power cable that will cost about $1 BN for a capacity of 2 GW. This power cable will be across the Mediterranean Sea, much shallower than the Pacific, but let's ignore that. The distance between Australia and Japan is about 6800 km, so you'd need a cable 5 times longer than the one above. This would translate in about $2.5 BN of capital investment per 1 GW of electricity.

[1] https://www.submarinenetworks.com/en/power-cable/a-1-208km-e...

[hokkos]

Except H2 carrier won't carry 1/2 LH2 as LNG but 1/4, liquefaction will consume 35% to 45% of the LHV energy, 9 times more leaks than LNG, completely new infra, and all existing H2 carrier have issues we are nowhere near building them as the same size of LNG and it will cost way more :

https://twitter.com/MLiebreich/status/1596449504194367488

[credit_guy]

Your right, but...

- I never mentioned H2 carriers carry 1/2 the energy of LNG. I used the 8.5 MJ/m3 LHV density of H2, which is 38% of the one for LNG, of 22.2 MJ/m3 [1].

- the 35% to 45% liquefaction energy cost. [2] is a paper written by the Department of Energy stating that the range in the industry (as of now) is 10-20 kWh/kg, which is 30% to 60%. Which means 30% is possible. If we massively scale up this industry, lower values are conceivable

- 1% losses to leaks per day. This number is pulled out of a hat (you didn't mention it, but the tweet you linked to did). The leaks of H2 are not very well studied, so 1% is just a conjecture, and probably a very pessimistic one. [2] is a review of the literature done in July 2022. It finds estimates for lifetime leaks of between 0.2% and 3%. Not daily leaks.

- existing H2 carriers have issues. Of course. The economy is geared towards LNG carriers at this point. 20 years ago LNG carriers were a curiosity, and now they are an essential part of the world's energy infrastructure. LH2 carriers are not needed at this point, since the H2 production is just a drop in the bucket compared to natural gas.

- the H2 infrastructure. We don't need to replace all the natural gas infrastructure with H2 infrastructure. As you may have noticed, there's been some noise recently about retiring natural gas stoves for homes. The move is towards replacing a lot of natural gas infrastructure with power cables. H2 will just be needed at the receiving terminals, where it's going to be stored locally, and converted to electricity based on demand.

[1] https://en.wikipedia.org/wiki/Energy_density#List_of_materia...

[2] https://www.energypolicy.columbia.edu/research/commentary/hy...

[planede]

What about the cost of the supporting infrastructure for cramming that 1GW into hydrogen and back to electricity? Well, with fuel-cell cars you don't need centralized infrastructure for converting back, but then you need infrastructure to distribute it inland. You still need the supporting infrastructure on Australia's side for the electrolysis.

Of course the power cable would also need supporting infra, other than the length of the cable, but I have a hunch that it would cost way less. I have no numbers though.

[kortilla]

4 carriers is not enough if you need this to be reliable. That’s a long trip across an ocean on a route that gets some bad weather.

[bigger_cheese]

There was literally an article in the news today about all the problems they are having building a cable from Australia to Singapore

https://www.abc.net.au/news/2023-01-23/sun-cable-demise-show...

From the article "Crucially, he argued the subsea cable was likely to be its steepest hurdle, pointing out that it was more than five times longer than the world's biggest, the 767-kilometre Viking link between the UK and Denmark currently under construction"

[eru]

They are building a cable from Australia to Singapore. Going to Japan is in a similar order of magnitude.

[defrost]

Nope.

The length was fine .. the single breakable deeply submersed part where it crosses multiple faultlines in an earthquake rich volcanic region was bonkers.

See:

Atlassian CEO's bonkers scheme to pipe electricity from Australia to Singapore collapses

   4,000km extension cords are hard to build

https://www.theregister.com/2023/01/22/suncable_collapses/