[James Jenkins]

James Jenkins  asked the Naked Scientists:
   
Lately I've been  thinking of an  idea that might help the world's energy crisis.

People are battling to find a reliable  renewable energy source. We have tried everything - OR HAVE WE?

What if the ocean could be used as a force,  but not just as tidal or wave energy, but something  bigger.

My Idea - If you had to place large metal pipes into  the ocean the water would flow through the pipes, if not you could insert one  way valves into the pipes so that when the water enters it does not exit again.  From there the water will travel through the pipes until it reaches the end,  where it will exit the pipes and flow over a series of turbines. The  turbines will then spin which will in turn run a series of generators which will  be able to supply  power.  Please if you would be so kind as to share  your opinion and thoughts about my idea, I would be very  grateful.

Kind regards,
James  Â   

What do you think?

[Geezer]

James,

Alas, from your descrption it sounds if it cannot work. The problem is that after the water has driven the turbines, there is nowhere for it to go. There are a few places on Earth that are below sea level, but once you had filled them up with water, the water would stop flowing through your pipes.

Regards,
G

[CliffordK]

James,

I agree with Geezer, your description is a bit confusing. 

Energy can be derived from changes of levels of water.  Changes in pressures.  Flow of water.  Perhaps even temperature gradients.

If you plunged an empty pipe to the bottom of the ocean, then filled it, once it became full, it would take an equivalent amount of energy to empty again, so there would be no net gain.

However, there is certainly a lot of energy in the oceans that could potentially be used.

You mentioned wave energy.  It might be difficult to capture, but certainly one gets lots of waves in some places.  As far as the pipe, one might be able to direct the maximum elevation that waves crash into rocks into pipes and turbines, releasing the water back into the ocean at a lower level.  But, it may be difficult to capture a high enough volume to make it worthwhile, and the tides might be frustrating with different elevations.

Another place one might be able to capture a lot of energy is in the deep ocean currents.  These currents have more flow of water than the rivers on the surface of the continents.  But, there will be significant engineering challenges to build equipment to withstand the saline environment as well as the life at the sea floors, and to capture these currents, and finally to transmit the energy to shore.

Just like geothermal heating that is now being captured in many places, we could also capture a very large amount of very cold temperatures just off the coasts around the world with deep ocean temperatures down to nearly freezing.  Consider the potential of using the deep oceans for air conditioning in Florida where the temperatures on the continent are significantly hotter than at the depths of the oceans.

I suppose the greatest risk would be making signification alterations to natural systems without fully understanding them first.

[MikeS]

James
I think what you are describing are ducted turbines.  You could pick up energy from the gulf stream etc.  The problem is one of scale and hence cost.  I believe that (non ducted) turbines are used, or have been proposed to be used somewhere around the coast of Florida?  They are certainly used in some American rivers.

[Johann Mahne]

I think what you are describing are ducted turbines.  You could pick up energy from the gulf stream etc.

I can see the headlines: "UK freezes over as the gulf stream stops flowing"

[Don_1]

I get your drift James (pardon the pun). But the trouble is your tube would be more likely to restrict the flow of the ocean current. What's more, ocean currents have a tendency to change direction, so your pipe might not always be in direct line with the flow. You'd be far better to have a turbine where flow is restricted, such as a river mouth.

A great place to site such turbines would be at the Thames Barrier.

[Soul Surfer]

Reliable tidal and other currents are already being used as a source of power bit they use underwater windmills rather than pipes because pip[es tend to lose energy and can be a problem with some sorts of hydroelectric systems