[nocoiner]

Can you elaborate on the use of photovoltaics in shipping? After a few searches, I haven’t been able to find anything that suggests the marine industry was an important sector for its development.

Also, I feel extremely confident predicting that the commercial maritime industry will never ever pay a premium for a particular fuel source. There may eventually be some applications where fusion is most efficient, but fusion reactors aren’t going to make their debut in cargo ships.

[defrost]

I suspect they're referring to the use of PV cells in lighthouses, Light-Buoys, Wireless Relay Stations, LORAN (pre GPS marine navigation) stations, etc.

Economics at the time restricted their limited use to mountainous areas, deserts, isolated areas, remote island outcrops, etc.

I saw PV use in the 1970s in remote Austalian rail operations to power signal boxes and repeaters .. the higher costs offset the equally high costs of maintaining a fueled generator in a remote location.

Marine shipping wasn't, to the best of my recollection, directly using PV's shipboard as they already had massive engines driving propulsion and it was trivial to bled off a little torque for a electrical generator.

[nradov]

Sailboat owners were early adopters of photovoltaics in order to avoid having to run generators. Some newer merchant ships have installed photovoltaics to supply part of the hotel load and maybe save a tiny amount of fuel, but that's a newer development and probably more of a "greenwashing" thing.

[defrost]

Addendum:

I should have addressed this in my peer comment, from the Launch HN header above

  Why ships? They don’t have great alternatives—the shipping industry is desperate to decarbonize. Hydrogen and ammonia are being explored, but come with serious downsides: low energy density, flammability, leaks, and massive infrastructure challenges.

Is a bit odd from my PoV as it skipped over methanol .. the "green" fuel of choice in shipping today, with supply contracts already inked and signed, ships built, and more in pipeline.

DNV GL welcomes Lindanger to fleet – world’s first methanol fuelled ocean-going vessel (2016)

  “We are very pleased to see the completion and launch of this exciting and innovative newbuilding,” says Knut Ørbeck-Nilssen, CEO at DNV GL – Maritime.

  “This is the first time a dual-fuel engine with a Low Flashpoint Liquid (LFL) fuel system has been installed on an ocean-going vessel and it is a testament to the excellent cooperation between all the project partners that we have been able to complete this unique project and gain flag state approval. Methanol as a marine fuel is a very promising option to enable owners to reduce the environmental impact of their vessels and to comply with low sulphur and ECA regulations and we look forward to working on many more projects using this innovative marine fuel and technology.”

~ https://www.dnv.com/news/dnv-gl-welcomes-lindanger-to-fleet-...

Methanol as fuel heads for the mainstream in shipping (2023) - https://www.dnv.com/expert-story/maritime-impact/Methanol-as...

Also - https://www.methanol.org/marine-fuel/ and https://www.methanex.com/about-methanol/marine-fuel/

[algo_trader]

Here is latest (2025) bio methanol project from China [1], at $150/barrel of oil equivalent

And its not even true e-methanol which will be $200-$300boe

[1] https://mp.weixin.qq.com/s/Va0XYtSXQJLVrOZsW5obXA

(if u have any actual contact with the maritime industry would love to connect and chat)

[defrost]

My background is more mining, exploration geophysics, and global mineral resources. I have an interest in related production projects, eg: marine transport is part of mining and we (Australia) have several green methanol projects ~300K tonne per annum coming up this year, entering a global market of some 330 million tonne of general marine fuel.

[dredmorbius]

PV energy capability per unit surface area is low enough that it's impractical for large-scale propulsion.

Marine PV has seen use on pleasure craft (particularly sailboats) for auxiliary power needs (electronics, nav, lighting, pumps, light cooking/heating), and for drone craft (there was a startup out of Alameda, CA, producing what seemed to be aimed as US Naval marine survey craft a few years ago, largely wind-powered but with electronics and back-up propulsion powered by solar arrays, see: <https://newatlas.com/marine/72-ft-autonomous-saildrone-map-s...>.

Wind-capture remains the most viable alternative to fuel-based marine transport, and "windjammers" remained in commercial operation through the 1950s particularly on very-long-haul routes, though ultimately even that niche was captured by oil-powered propulsion. See: <https://omeka2.hrvh.org/exhibits/show/a-new-age-of-sail/last...>.

Containerisation probably accelerated and/or solidified that decline as this permitted not only far more efficient loading and unloading, but requires clear decks and permits vastly larger ships and concommitantly greater crew efficiencies (crewing is almost entirely independent of ship size and capacity, so a larger and faster ship (factors which also trend together given hull speed and its relationship to length) is virtually always vastly more efficient than a smaller one, despite possibly greater total fuel consumption. Fuel use itself per unit cargo is also lower for larger shipping.

Current ship-size constraints are largely determined by harbour and canal dimensions (hence ship dimensions defined by <location>max, e.g., Panamax, Suezmax, Chinamax, Batimax (Baltic Sea, not Baltimore Harbour), etc. I'm fond of the designation "Handy Size", which calls to mind "fun sized" though I'm told there's little relation. Maximum length capable of sustaining large seas (waves) without keel breakage is another marine engineering consideration which has limited ships to ~1,200 ft / 660m maximum length. At larger sizes ships are simply too susceptible to coming apart in heavy conditions.

Ships in general are constrained by the smallest viable dimensions of a port of call or route, and larger ships have fewer viable available ports or routes, though the busiest of such tend also to favour larger hull dimensions.

<https://en.wikipedia.org/wiki/Cargo_ship#Size_categories>

<https://en.wikipedia.org/wiki/Handysize>