Energy Options > Wind Power

Sailboat wind power turbine?

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mangyhyena:
I'm just throwing an idea out to see what you all think.  I put it in the wind power section, but the generation and storage aspect could be applied to just about any system designed to harness our ocean's energy far from land.  Ships could be sent to collect the energy and bring it back to shore.

To charge a small battery bank on a sailboat, I was wondering about the feasibility of dropping a turbine in the water.  I was thinking that as the wind pushes the boat, the turbine in the water should turn as it is pulled/dragged through the water, charging the battery bank.

It would slow down the sailboat when operating and I don't know how large it would need to be for the purpose of battery charging or how expensive it would be.

If it would work on a small scale, I wonder it could be scaled up to an industrial level.  A large ship with sails and a turbine or turbines beneath the stern.  Ship moves forward, turbine turns, electricity is generated.  The electricity could be stored either in batteries, perhaps Nickle/Iron for long service life, or converted to hydrogen and stored.  I figure that if the input energy is wind, rather than fossil fuel, the 3 to one ratio for electrolyzing water wouldn't be so bad for the environment or the input cost.  Hydrogen storage aboard ship would be harnessing and storing 1/3 of the total energy during a trip.

Anyway, ships like this would leave one port empty and arrive at another port full of energy ready to be offloaded.  Two ships, one at port A and the other at port B, going back and forth between ports, would bring in energy each time they arrived to each port.  Lots of them would bring in lots of energy.

Using modern weather forecasting and perhaps tethered "kites" to catch the wind currents at elevation might help make the system more efficient or reliable.
Anyway, it seems like a way to harness some of the natural energy in our oceans, which cover 70% of our planet and is currently unused for our energy needs.

I realize that the materials used to build the equipment leave a carbon footprint, but to be fair, so do the materials used to build new power plants.  At least the ships don't require the burning of fossil fuel to operate.

What say you all?  Another crazy idea that won't work?

never_retreat:
I don't think we could build anything big enough to meet our energy demands.
I think tidal would be easier to harness.

mangyhyena:
Build a large enough fleet?  You might be right about not being able to build supertanker-sized sailing ships unless it's for transporting oil.  Don't know.  During WWII, we quickly built a large fleet of war ships, but that doesn't mean we are capable of doing that again with energy harvesting ships.  I don't think anyone would argue that we , today, are the greatest generation, or anywhere near the greatest.

For tidal energy, I've been wondering if dams could be used, letting high tide in through turbines and low tide out through turbines.  Perhaps stock the dam with fish meant for food, like a fish farm.  Might be nice to go to the beach and know no sharks are swimming by you.  Then again, maybe it would be bad for sea life.  Don't know.

What I do know is there is a lot of kinetic movement in our oceans and we're not using very much of it.  There is plenty of room for equipment out there and if we could store even 1/3 of what is available, it would go a long way towards meeting human energy needs.

But, the moment we decide we can't harness ocean energy, wether or not it is viable becomes a moot point.  Hopefully, Exxon will help end our reliance on oil and coal.  :)

Skunkeye:
This system wouldn't really be harnessing ocean energy (the energy from wave and tidal action).  It's just harvesting wind energy, and pretty inefficiently at that.  You're using a lot of your captured energy to move the ship and overcome the drag of the water on the hull and the turbine.  It would be more efficient to just put wind turbines offshore, anchored to the sea bed like oil rigs, to take advantage of the higher winds out where there are no landforms or buildings to block them.

DIsregarding that, batteries would be a non-starter for such an application.  Lead-acid batteries have about 1/250th as much energy per pound as crude oil or natural gas.  Even the best lithium-ion batteries on the market are only five times better, so even if you could get past the enormous cost, you'd need 50 supertanker-sized ships to bring in the equivalent of one ship of hydrocarbons.  Hydrogen, if compressed highly enough, would have the energy density to make it practical, but the efficiency losses would be enormous.  Sailing a ship around, dragging a turbine behind it, to crack water molecules and compress the resulting hydrogen - that's a lot of lost energy.  I don't see how that could ever be cost-competitive even with solar, much less traditional wind turbines.

Capturing tidal energy through turbines is already being done, on a fairly large scale:

  https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station

  https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Plant
 
  https://en.wikipedia.org/wiki/Annapolis_Royal_Generating_Station

One idea that I've seen proposed that seems really cool is to attach tidal generators to bridge pilings.  The bridges are already there, so there's not much anyone can say about aesthetics or environmental impact, and it would be a simple matter to run cables up and along the bridge to bring the power to the grid.

gopack84:
If you've got some hours to kill, this is a really interesting course. It's called "Physics for Future Presidents" and he goes into a lot of detail about energy. The problem is that gasoline is just so really, REALLY good at what it does which is store a lot of energy in a small volume and mass. There's really not much else that is consumer friendly that can compete on cost and most everything else has additional problems hydrogen (delivery and stability), batteries (cost and capacity and conversion losses), nuclear (well... lots of problems to make yourself a nuclear powered car), solar (efficiency of photovoltaics and just the total available energy per sq meter from sunlight), and so on.

Definitely worth a listen if you're brainstorming alternative energy I think. The course is designed to be a high-level course with a minimal amount of math needed to prove things to yourself. The downside is it is probably nearly 30 hours of material, but you can pick and choose because the internet is great.

http://www.youtube.com/watch?v=6ysbZ_j2xi0&list=PL095393D5B42B2266

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