SoylentNews is people
SoylentNews
It's quick, it's quiet, and it's covered in 300 square meters (3,229 sq ft) of solar panels. The 78-ft (24-m) electric SolarImpact yacht is a concept designed as the first of its kind – an ocean-going solar-powered yacht. An 800-kWh battery on board gives it 10 hours of cruising capability, which can be extended by topping up the battery when the Sun's shining.
The yacht's giant solar array, which covers the vast majority of its upward-facing surfaces, can generate up to 320 kWh a day if they're getting lots of sun. They can serve as the vessel's sole power source if conditions allow, and you're prepared to take your time.
Although this 70-ton aluminum-hulled beast boasts 1,000 kW (1,341 hp) of all-electric power and has an impressive maximum speed of 22 knots, if you're running all the regular systems solely on solar, you will be able to cruise indefinitely, but only at a slow 5 knots – which would take you around the world in about six months if there wasn't a whole lot of land in the way.
Sea-steaders, rejoice!
(Score: 4, Interesting) by suburbanitemediocrity on Wednesday September 19 2018, @07:14PM (16 children)
I did the numbers once for a solar powered boat and it's a feat they got it to do anything.
(Score: 3, Informative) by VLM on Wednesday September 19 2018, @08:23PM (2 children)
You got modded funny but I did the same math and got the same result.
I think anyone who's ever seen a sailboat with a solar panel, some batteries, and an electric trolling motor has had a "hmm" moment, leading to some math, leading to "this isn't going to work..."
It does work if your range is, say, half a mile across the harbor. Purists will make fun of you for not trying that under sail or being patient enough to wait thru a calm, but more pragmatic people are "f it" and use the trolling motor, leading to "I wonder if the solar panel could run that dude 12 hours per day"
I also remember I made a pitiful attempt at "righting moments of inertia" or that stability plot of angle of heel vs righting force or whatever its called and putting thousands of pounds on the roof of a sailboat usually did nothing for stability statistics. The center of balance is usually belowdecks for most ships (lobsta trawlers maybe exception?) so you can't go by sheer bulk capacity alone.
(Score: 3, Informative) by JoeMerchant on Wednesday September 19 2018, @08:33PM
If you pack on enough batteries (preferably down low), a solar system can charge them all week long and give you a couple of hours of cruising on the weekend. Without a sail, forget it (or charge off dock power all night long.)
Also, bring a checkbook, no way you can safely transport all the $100 bills required to pay for such a system.
🌻🌻 [google.com]
(Score: 0) by Anonymous Coward on Thursday September 20 2018, @07:56PM
I seem to recall something about solar fabrics, targeted at generating electricity with clothing, but could "solar canvas" be used for sails? Would a turbine (spun by water) generating energy while sails are deployed lead to too much drag or some other kind of instability? Personally, I've been waiting for some of Harry Harrison's ideas to be implemented...
(Score: 4, Informative) by JoeMerchant on Wednesday September 19 2018, @08:24PM (11 children)
I "do the numbers" for electric vehicles every couple of years.
20 years back it was basically no-go, at least for what I would call a practical use case (car, boat, whatever...)
15 years back (lithium batteries starting to show up in production quantities) it became more a case of "sure, you can do it, but how much are you willing to spend on something that's barely practical to use?"
10 years back the supporting technologies started coming together to the point that you could buy more integrated systems "off the shelf" and make things go with less detailed engineering. Costs for any vehicle I would want still were running $100K+ just for the motors, batteries, controllers and charging circuitry.
5 years back costs were coming down, but the cost for my "custom conversion" car was still about the same in parts as to buy a Tesla Roadster new, for similar performance.
Sailboats are "almost there" today, if you only need the motor for marina maneuvering. If you intend to run significant distances on electric power, I've heard figures quoted like: 1kWh per mile cruised at 1/2 hull speed for something like a 17000lb 34' sailboat. 1/2 hull speed is not even 4 knots, so that's not going to be an attractive replacement for diesel (for me) until there's upwards of 25kWh of storage onboard, and unless you're scrounging used batteries lithium costs about $500/kWh, the PowerWall is a good deal at $5900 for (advertised) 13.5kWh useable capacity, but... if you're wanting to run a 12.5kW motor, you'll need qty. 3: 5kW PowerWalls, installed cost > $18K, and a weight > 825 lbs just for the batteries, about the same as a full 100 gallon tank of diesel, for something like 5% of the range. Even some of the people who sell regen kits on the sailboat motors will tell you: regen doesn't usually work too well, or at all, in most existing sailboat prop-drive configurations. Solar works, and is improving dramatically, but 100 square feet of solar panels only gives 1.4kW, and if you want the fancy flexible direct-on-hull solar panels that you can walk on that 1.4kW (totaling an average of ~5.6kWh/day) would run about $16K. So, if you're O.K. with 18K for batteries that might carry you 40 miles in calm water (much less with any headwinds/waves), 16K for solar panels that will take a week to charge them, a 12.5kW motor, charger and controllers at $6K-12K shouldn't be too much for you. At this point, we're just about as heavy as a typical diesel powerplant, but with tremendously reduced range, max power, and a cost upwards of $45K (equivalent new diesel power, tanks and all, should run less than $15K, installed.)
But, the solar cells charge the batteries "for free", yeah, 2000 times, and then it's time to replace the pack. If you've spent $18K on your battery pack, that's $9 per discharge cycle, or about the equivalent of 3 gallons of diesel which could have given you more flexibility, and higher max power.
Still, the silent, fume free drive system is a big thing, I love my e-bikes, even the cheesy Sondors Original (which has a practical heavy assist e-range of about 10 miles at 20mph.)
As for this mega-yacht, hull speed is much better due to the length - closer to 12 knots, and cubic dollars don't seem to be an issue. By covering the whole top surface in solar, they're possibly at break-even for a slow cruise, on a sunny day. Like the bikes, if I had the money, I'd get one just for the grins.
🌻🌻 [google.com]
(Score: 2) by VLM on Wednesday September 19 2018, @08:42PM (1 child)
Here's how to verify the numbers: A 30-footer will probably have around 10HP to reach hull speed and speed is non-linear with power so I could totally see a mere couple HP pushing a cruiser up to half hull speed. So if 3 HP pushes the thing up to 4 knots for an hour, thats about right, 1 kWh per mile.
(Score: 3, Informative) by suburbanitemediocrity on Thursday September 20 2018, @09:16AM
Ocean currents can reach up to 6 knots.
(Score: 2) by deimtee on Wednesday September 19 2018, @09:53PM (6 children)
I'm assuming a regen kit uses wind to push the boat, which drives the propeller connected to a generator.
If you did optimise for power generation on a sailboat, ie. larger prop, slower RPM, higher torque etc, how much power could you generate? Just thinking about it, it seems like it could be significant.
You have a large sail area to catch the force of the wind and ground based hydroelectric generators get around 90% efficiency.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by JoeMerchant on Thursday September 20 2018, @01:55AM (5 children)
In theory, quite a lot. In practice, you're not often "overpowered" by the wind, so usually any power you extract from the prop will translate to lower speed through the water - in high enough wind conditions where hull-speed is the limiting factor regen gets a whole lot more attractive since it won't significantly slow progress.
Then, there's the fact that existing props and shafts are placed and designed to push the boat, not to catch passing water and generate power from it. Not common on sailboats, but a jet drive is an excellent extreme example of a propulsion unit that can move the vessel forward quite well, but extract energy from the vessel moving through the water quite poorly. Of course, common on sailing boats, feathering props won't generate any power at all, by design. But, if you go for a fixed prop and put up with the extra drag even when not generating, you can probably get a few kW while underway at near hull speed (~7 knots), particularly if you have a planetary gearset which can re-gear to optimize generation from the passing water.
All in all, solar is a whole lot less fuss, and even wind turbines seem to be more popular/practical than sail-power prop-shaft generation.
🌻🌻 [google.com]
(Score: 2) by deimtee on Thursday September 20 2018, @02:53AM (4 children)
But what if you didn't care about going slow, and were just going to cruise across the ocean mining bitcoin? :)
I actually meant a design that was optimised to extract power. Something like a catamaran where the bit between the hulls funnels into a turbine. If the funnel/turbine were lightweight and retractable, you could charge your batteries when you weren't in a hurry and still have nearly full speed when you were.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 0) by Anonymous Coward on Thursday September 20 2018, @02:53PM
One of the reasons that boats don't sink anymore is that, due to weather forecasting, they usually have enough time to get out of the way. Sailboats can do about 100-200nm/day under sail or power. Speed is counted as a safety feature, and you need lot of them.
(Score: 2) by JoeMerchant on Friday September 21 2018, @02:24AM (2 children)
Yes, you could. I still think that solar cells plastered to the top surfaces are a lot less fuss and bother, for better gain in anyplace I'd want to be sailing (yes, above the arctic circle in winter the wind powered generators will win, but... who wants to go there?)
🌻🌻 [google.com]
(Score: 2) by deimtee on Friday September 21 2018, @06:11PM (1 child)
Solar cells are great where you have a lot of surface to mount them on. There is a specific use case I was thinking of. I know some people who go somewhere between 2 and 20 km off the coast, slowly drift along fishing for most of the day, then go home arriving just before dark.
Each day they do this, it costs them fifty to a hundred dollars (AUD). Over their average two week holiday, they spend more than a thousand on fuel, plus there is all the weekends they take the boat out.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 2) by JoeMerchant on Friday September 21 2018, @09:36PM
The short answer is: if they're spending 50 to 100 AUD on fuel, they'll be spending a VERY large multiple of that on batteries to hold the energy of the fuel, and the batteries will end up weighing quite a bit more.
If money is the problem: get a trawler and be content to motor at 15kph or so - they might spend an extra hour each way on the travel time, but their fuel cost would drop by a factor of 5 to 10. Odds are, they could motor their current fishing boat at 15kph and dramatically reduce their fuel consumption - it's just that the trawlers are designed to travel like that so "feel" a bit better while doing it, and can also be quite comfy on the inside...
Around here, boats like this: https://www.boattrader.com/listing/1991-albin-32-sportfisher-twin-diesel-103160017/ [boattrader.com] in good running condition but less than stellar cosmetics occasionally come down under $20K asking...
🌻🌻 [google.com]
(Score: 2) by suburbanitemediocrity on Thursday September 20 2018, @09:31AM (1 child)
I used to sail a bit and hope to again someday and technology is not 'almost there'.
Batteries have nothing to do with it, it's all about energy density from solar panels...about 100w/m^2 max, People I've listened to who do long distance cruising have to ration power to keep their autopilot alive and most use a passive windvane steering mechanism. You might get half hull speed on a calm day, but a headwind on the surface area of a boat will push you backwards, sail or not. Hove to boat can drift tens of miles overnight.
(Score: 2) by JoeMerchant on Friday September 21 2018, @02:32AM
There are some devotees who claim it's awesome stuff. I think they mostly charge up their battery banks from shore power and just use the electric auxillary for docking / undocking maneuvers.
We've been looking at buying a cruising yacht (either sail or a diesel trawler) and you see all kinds of stuff where people have setup solar and wind generators and hear all these great stories about what they can do, but... it's about all that a $300 solar panel can do to charge up a cellphone on a sunny day. A/C is an interesting use case: 16000 BTU draws ~1.5kW, which you might get out of 300 sq ft of solar panels, so... if the sun is shining really hot, you just might be able to fire up the heat exchanger and reject some heat (and humidity) out of your cabin air into the sea - if you've got 30' x 10' of surface to put the panels on (and about $50K for the fancy walk-on solar panels....) Of course, a little 6kW diesel generator charging up a battery bank could do the job for less than half the cost, for 10+ years.
🌻🌻 [google.com]
(Score: 2) by RS3 on Wednesday September 19 2018, @09:36PM
Article doesn't say, but it looks like a catamaran, so it should be much more efficient than standard single hull.