Electric Ocean Cargo Ship with Wind/solar Charging stations along the route

[Electrifying]

Electric ships have been popping up but most I hear are either ferry boats or short range shipping. For a half million ton oil tanker to be electric , it needs to be charged along its route. How feasible is it to have anchored or semi-floating wind/solar powered mega-chargers along busy shipping routes to charge these ships? These charging stations can be backed by many power packs so their peak charging rate can be many MW's. It'll be nice to have a huge container ship to get charged in one of these stations for 1 hour and that amount of charge will allow it to sail for another 500 miles to reach the next charging station.

 

[TheTalkingMule]

I think the question to ask is.....What's the drag on 5MW of floating thin film solar trailing behind a tanker for 1/4 mile?

 

[wart]

Why not just put windmills on the ship? I mean, it's not like wind-powered ships are a new idea. Though I suppose if the windmills are in a fixed location you have the ability to put them in a place with lots of steady wind.

Also, there's a school of thought that with the rise of 3D printing/automated manufacturing, more products will be manufactured close to the consumer and there will be less demand for large-scale intercontinental shipping anyway.

 

[Todd Burch]

Why not just put windmills on the ship? I mean, it's not like wind-powered ships are a new idea. Though I suppose if the windmills are in a fixed location you have the ability to put them in a place with lots of steady wind.

The Law of Conservation of Energy/First Law of Thermodynamics make that impossible.

Putting wind turbines on the ship itself would increase the drag of the ship and act as sails themselves, pushing the ship back against the wind. The energy the windmills would generate would be cancelled out by the energy needed to overcome this resistance. In fact, since energy is lost in conversion, and a lot of other factors (increased weight and therfore water displacement by the ship, etc) it would actually be far LESS efficient to have wind turbines on the ship.

WRT the OP’s idea, it would be possible but probably not practical at this point. Wind turbines would have to be anchored somehow. A floating solar field would have to be resistant to storms and high seas.

You would have to make a “net” of individually floating panel pieces tethered to each other but constrained not to crash into each other during high seas.

A huge barge could potentially do the trick and maybe even serve as an anchor to mount turbines as well, but I suspect the cost wouldn’t be practical.

You’d also probably need to anchor it to the sea floor or have electric motors constantly keeping it centered on a GPS location.

Neat idea though, and maybe it will happen eventually.

 

[TheTalkingMule]

There are certainly floating wind turbines, but to have some kind of mid-ocean battery charge/swap setup you'd likely have to piggyback off a military application. That's just too much effort and resources to get done naturally by the market itself any time remotely soon.

That's international waters so maybe a private fronted, CIA operated network has applications 20 years down the line? On the surface(literally) it's a cargo "fueling" station, but 200ft below they're charging unmanned surveillance submarine drones.

Plenty of sun, wind and wave power out at sea, it's an interesting system to think about.

 

[wart]

The Law of Conservation of Energy/First Law of Thermodynamics make that impossible.

Putting wind turbines on the ship itself would increase the drag of the ship and act as sails themselves, pushing the ship back against the wind. The energy the windmills would generate would be cancelled out by the energy needed to overcome this resistance. In fact, since energy is lost in conversion, and a lot of other factors (increased weight and therfore water displacement by the ship, etc) it would actually be far LESS efficient to have wind turbines on the ship.

I get what you're saying, but it's not actually that simple, because you're not trying to move relative to the wind, you're trying to move relative to the water. If your thermodynamics-based explanation were correct then sail-powered boats would never go anywhere. As long as the WIND is moving relative to the WATER it is possible to exploit the difference between the two and move your vehicle relative to the WATER.

Wind turbine powered vehicles are absolutely possible and have been built.
Wind-powered vehicle - Wikipedia

 

[Todd Burch]

I get what you're saying, but it's not actually that simple, because you're not trying to move relative to the wind, you're trying to move relative to the water. If your thermodynamics-based explanation were correct then sail-powered boats would never go anywhere. As long as the WIND is moving relative to the WATER it is possible to exploit the difference between the two and move your vehicle relative to the WATER.

Wind turbine powered vehicles are absolutely possible and have been built.
Wind-powered vehicle - Wikipedia

My response refers to capturing the energy in the relative wind generated by the forward motion of the ship (so, assuming zero wind).

And yes, rotor-powered vehicles are possible--and demonstrable with small, lightweight aerodynamic wheeled vehicles in which the energy captured due to motion of wind relative to the vehicle can be enough to overcome the low air resistance and mechanical drag.

But since there isn't always a relative wind (sometimes the wind doesn't blow--I'm a degreed engineer and meteorologist so I know this , and sometimes you're traveling in the same direction and at the same speed as the wind, you won't have any generation in those cases.

Suppose you have a ship that requires 5 MW of power to cruise at 5 m/s through the water. If the wind is blowing 5 m/s to the east, and you're travelling from China to the US, you'd have zero relative wind and would have to supply the power via batteries. A 25 day trip (about 11,000 km at 5 m/s) with a power requirement of 5 MW would require a battery pack in this situation of 3 GWh! That would make the Hornsdale system look puny in comparison.

Going back from the US to China with a 5 m/s easterly wind and cruising at 5 m/s, you'd have a 10 m/s relative headwind. If your rotor could capture 100% of the energy, AND if the system could convert it to electricity, store it, and re-extract it from the batteries and turn the motors with zero losses, AND if the rotor system itself had zero induced or aerodynamic drag losses, it would have to be generating 10 MW: 5 MW to keep the ship going, plus another 5 MW to store for the wind-free return trip.

To generate 10 MW with a 10 m/s relative headwind, you'd need a 150 m diameter (almost 1/10 of a mile!) turbine strapped to the ship! And that's assuming zero losses.

So theoretically it's possible, but not practical. In reality, the wind situation is a bit better, but there are losses in the real system. The key is that you would need a massive battery storage system and a massive turbine to make it work.

 

[wart]

My response refers to capturing the energy in the relative wind generated by the forward motion of the ship (so, assuming zero wind).

And yes, rotor-powered vehicles are possible--and demonstrable with small, lightweight aerodynamic wheeled vehicles in which the energy captured due to motion of wind relative to the vehicle can be enough to overcome the low air resistance and mechanical drag.

But since there isn't always a relative wind (sometimes the wind doesn't blow--I'm a degreed engineer and meteorologist so I know this , and sometimes you're traveling in the same direction and at the same speed as the wind, you won't have any generation in those cases.

Suppose you have a ship that requires 5 MW of power to cruise at 5 m/s through the water. If the wind is blowing 5 m/s to the east, and you're travelling from China to the US, you'd have zero relative wind and would have to supply the power via batteries. A 25 day trip (about 11,000 km at 5 m/s) with a power requirement of 5 MW would require a battery pack in this situation of 3 GWh! That would make the Hornsdale system look puny in comparison.

Going back from the US to China with a 5 m/s easterly wind and cruising at 5 m/s, you'd have a 10 m/s relative headwind. If your rotor could capture 100% of the energy, AND if the system could convert it to electricity, store it, and re-extract it from the batteries and turn the motors with zero losses, AND if the rotor system itself had zero induced or aerodynamic drag losses, it would have to be generating 10 MW: 5 MW to keep the ship going, plus another 5 MW to store for the wind-free return trip.

To generate 10 MW with a 10 m/s relative headwind, you'd need a 150 m diameter (almost 1/10 of a mile!) turbine strapped to the ship! And that's assuming zero losses.

So theoretically it's possible, but not practical. In reality, the wind situation is a bit better, but there are losses in the real system. The key is that you would need a massive battery storage system and a massive turbine to make it work.

Thank you for the thorough explanation. When you appealed to the First Law I assumed you were saying a wind-powered ship was impossible (i.e. a perpetual motion machine). I see now that you're saying it's just impractical.

 

[Todd Burch]

What I was saying was impossible was using a turbine from the wind generated by moving forward to power the ship. (Zero wind situation).

If you had a turbine/battery system, you could do the charging while in port for the return trip. But that would still require a large wind turbine and a massive battery pack.