Waymo's usually something like 50% more expensive than Lyft in SF, in my experience. But the drivers don't tailgate, have colds, listen to your conversation (AFAIK)...I'll generally opt for Waymo now if I have a choice. The biggest problem I have is that it's usually a longer wait due to the smaller fleet size, but if I'm planning ahead, I'll just book one for a given time, and that takes care of it.
A classmate dropped out in his sophomore year, and 10 years later asked to come back and finish. Caltech said sure, and aced the courses and earned his degree.
I asked him, were you smarter after 10 years? He laughed and said nope, he was just willing to work this time!
(Another gem about Caltech - once you're admitted, they'll give you endless chances to come back and finish. Your credits did not expire.)
One of my friends finally graduated after 6 years there. He endured endless students mumbling "7 years, down the drain!" as they passed by. (The line was from Animal House.)
Yep. Bright light does the same thing. Also, in dim light, I'd expect this to make it pretty hard to see. My optometrist mentioned it to me, but neither of us could see the point.
"Downtime for maintenance is part of normal operations, making this a far more forgiving early application of fusion, unlike the grid where every down hour is lost revenue."
Planned maintenance, sure, but unplanned maintenance means the same lost revenue, plus you're stuck floating in the middle of the pacific ocean, possibly in need of parts or debugging expertise that only exists half a planet away or, for that matter, food. It's certainly a good idea to find a niche to make market entry easier, but I would guess that reliability requirements are actually higher for ships than for microgrids. Find some isolated town or island running off flaky diesel generators on shipped-in fuel and negotiate a reasonable SLA.
This ignores, of course, the bigger problem: making fusion work at all at Q > 1. If it were me, I'd work on solving that before worrying too much about optimizing market entry. So far every single fusion effort has failed to clear that hurdle, and any effort on the other parts is wasted if you can't actually make power.
The first ocean-going steamships still had sails - it took many years for steam power to fully displace sail. Presumably a new maritime power system, like fusion, would follow a similar pattern.
Let's be realistic, it would have a diesel engine as a plan B.
But if you like sails: my pet hypothetical technology is wind-driven hydrogen tankers (or tankers for some other e-fuel derived from hydrogen) that sail out empty, then cruise around wherever there is plenty of wind. They'd have a turbine/generator setup driven by the water passing by and use the energy harvested there for filling the tank. Cruise around as long as it takes to nearly fill the tank then return to port (and fill the rest on the way back). There's a lot of oceans where systems like that could cruise around on. (same concept could also be used for desalonation, there it would not only be about energy but also about avoiding local brine concentrations)
The largest Q-Max-class gas tanker is 345 meters long [1]. Let's say you manage to fit 3 giant Siemens wind turbines on it, with 100m long blades [2]. It's a bit cramped but let's say you have extenders on the side to make room for all 3 of them. And also let's say you found a way to prevent the ship from tipping over when the wind is strong. By deploying floaters on the side or whatever. Not unsurmountable.
Each of those wind turbine has a rated power of 14.7 MW [2]. Let's say that you found a place where the wind blows super strong (but not too strong) and steady all the time. It's possible, since you are a mobile ship, after all. Let's say that you have a way for the ship to keep in the same place despite the strong and steady wind pushing you constantly. Using engines is going to lower your efficiency, so let's say we found another way.
So, now your ship is generating 45MW constantly. According to ChatGPT, this is 32 kg of hydrogen per second, taking hydrolysis losses into account.
Tanker capacity is 18 620 000 kg of liquid hydrogen. It will take 581 000 seconds to fill up. 9697 minutes, 161 hours, or 6.7 days. Much shorter than I thought... Did I miss something?
You have it reverse wind turbines need mooring, stay upright and so on. That's highly impractical. No, you build a fast-going sail vessel (using big traction kites, because it's not the 19th century anymore) and power the generator from much smaller turbine blades in the water. Hydrogenerator is the term established in recreational boating.
I sure would not expect any returns in days, more like months or years. But if we (humanity) could just solve the purely man-made problem of piracy (or would it technically be salvage?), I believe that a robotic fleet of cruising hydrogenerators could be a huge contribution to our energy needs.
The main issue is that prevailing winds have a direction, and there's not a continuous open ocean path other than the Southern Ocean which is harsh even by the standards of oceans. Sure you can steer along trade winds in the Atlantic or Pacific but there's quite some efficiency loss.
(Give climate change another decade or so and the Arctic Ocean maybe becomes an option, although by then we'll have bigger fish to fry, or perhaps poach).
Boats go considerably faster, as in overcoming more water drag, going crosswind than going downwind. I suppose that adding extra drag with a hydrogenerator will change the maths of that relationship, but certainly not so much that it would be prohibitively wasteful to not specialize a hydrogenerator carrier to downwind-only. (if the downwind-only setup can be competitive at all, not sure I'd take that as a given)
It strikes me that having the turbine and hydrolysis plant fixed in place, and having ships visit those sites to refuel, is probably an easier setup than mobile turbines.
But I think your maths is wrong somewhere. Hydrogen supplies 33MWh/tonne, and you've stated the ship capacity as 18620 tonnes. 18620/(33*24) gives a generation time of 23 days, even before we allow for hydrolysis overheads.
Marine hydrogen isn't a terrible idea though. Tank weight and bulk is prohibitive for aviation, but less so for shipping.
There are only so many windy places to affix turbines to. There's a lot of ocean to cruise on.
The mobile hydrolyser (not a boat to solve shipping in a quasi perpetuum mobile away, but an energy harvester that focuses on just that) would solve mooring: the "lateral lift" of the boat would take care of that, just how your plain old America's Cup boat isn't just slowly dragged downwind. It would solve linkup: a serious cost component in not all too conveniently located off shore wind installations is the grid connection. And it would solve intermittency: hydrogen is inconvenient compared to hydrocarbons, but it's super convenient compared to getting even more electricity at a time demand on your grid is already satisfied to saturation.
(GP's math is likely wrong, but the assumption that you could somehow cram multiple turbines from the bigger end of market offerings on a boat and call it a day seems so far off to me that I never really looked at the numbers)
Ugh, turns out I suck at math too. At least attempting it before coffee.
The ship's capacity in MWh is 18620t x 33MWh/t = 614460MWh.
At 45MW generating capacity, an electric hydrolyser at 80% efficiency delivers hydrogen at a rate of 36MW. That will unfortunately take about 70 years to fill the ship to its maximum capacity.
On a more positive note, 36MW is still a heck of a lot of power, plenty enough to run a mid-sized cruise liner or warship. So a marine generating station with three of these turbines could, for example, refuel a liner once a month, and then that liner have enough fuel to cruise for a month, and so on.
This would require a fuel tank with a more reasonable 750 tonne capacity. That's still several times more than the Shuttle, but not beyond the realms of feasibility - and a stronger, heavier tank allows higher pressures / smaller volumes.
I am totally mesmerized by the idea of a floating hydrolizing platform , where ships can dock and load hydrogen fuel ( not sure what form suits best ).
Must start some economics of it. Also marine environment is very unforgiving...
Platforms are does-not-scale hard though: they require mooring and every bit of ocean floor is different. Drilling platforms come in multiple "species", as different as spiders, fish and birds. Roaming hydrolysers on the other hand would be one design fits any ocean. You'd want to build lots of them, more Model T than Death Star. And where a stationary platform would have to be able to brace a hurricane, the roaming unit would just go to a neighboring sea with a friendlier forecast. Or ride along on the edge, if power throughput has enough headroom.
But yes, fuel-based powerplant, likely as part of a hybrid drive running electric motors powering propellers themselves.
Marine propulsion is already pretty optimised for efficiency (turn on engine, set to cruise power, maintain for 14 days, little acceleration, starts, stops, and/or hills), so a hybrid setup would work pretty effectively.
The far greater challenges are Q>1 and reliable fusion within a ship's structure.
As one ridiculous-pong writer to another, I love your work. I really enjoy this kind of technical performance art, both to write and to view. It may also be part of why I juggle: "There must be a harder way to do this."
I implemented pong as a cellular automaton [https://news.ycombinator.com/item?id=19155205]. It was a fun synthesis of skills I'd built on a bunch of previous projects, some of them professional, many of them actually useful. It's basically the one hobby project that I've ever really completed; the others always seem to drag on, semi-finished.
They still have to renew your prescription for you. If you're running out in 5/7 of a month, but only getting renewed monthly, you're just changing the granularity, not the dose.
That's a great list; while not explicitly writing them out, we raise our kids by similar rules, and I think it's been a huge help. #1 is huge. We also explicitly answer any question they ask (barring privacy concerns). The answers vary based on how old they are, and what they're capable of understanding, but they can always ask for more detail if we guess wrong. It lets them know that there are no taboo subjects with us, and they can always come to us with their hard questions.
It did mean nuanced conversations about how not to ruin the "Santa Clause game" for other kids, etc.
This is beautiful; the motion of the legs reminds me of some giant scuttling insect. I'd love to have a coffee table like that. I wouldn't even want the motor, actually. It looks like you can just push it and have it walk smoothly, as if pushing a table with fixed-orientation wheels.
