Producing energy from the pressure at the sea bed

[LoneWolf]

I was wondering if anyone knew of any obstacles that researchers or scientists ran into when designing machines to manipulate the pressure at the bed of the ocean into energy. I though of a design and then did a search of the internet for any designs similar to see other obstacles that may have been discovered and ran into this site http://oilprice.com/Energy/Energy-General/Using-Water-Pressure-at-the-Bottom-of-the-Ocean-to-Store-Energy.html which uses the same concept as mine but mine integrates other machinery which already compensates for their issue.

[John Cuthber]

The obstacle is that the laws of physics say it can't work.

Essentially, the pressure is because of the weight of water above the sea bed.

It could only do work if it moved downwards and it can't because the sea bed is in the way.

[Sensei]

According to article, wind turbines or solar panels are producing energy first and using it to pump water out from tanks on the ground of ocean, when there is windy weather or sunny hot day. Tanks are now empty.

 

Then water pass through turbines and fill tanks back. producing energy (according to article 80% of that produced in 1st stage, so 20% is lost).

 

That's smart idea. Currently power stations have to lower their production when there is not enough power consumers on the other end of wire.

 

On the other hand, instead of building it at ocean ground, we can simply make large artificial lake.

Wind turbines and solar panels will be all the time used to pump water from ocean to lake, no matter if consumers need it or not.

And then energy will be just produced in normal dam.

I was wondering if anyone knew of any obstacles that researchers or scientists ran into when designing machines to manipulate the pressure at the bed of the ocean into energy. I though of a design and then did a search of the internet for any designs similar to see other obstacles that may have been discovered and ran into this site http://oilprice.com/Energy/Energy-General/Using-Water-Pressure-at-the-Bottom-of-the-Ocean-to-Store-Energy.html which uses the same concept as mine but mine integrates other machinery which already compensates for their issue.

 

Which "their issue"? In article I don't see they mention any issue.

 

Do you mean you have created 5 times stronger concrete?

Edited May 9, 2014 by Sensei

[LoneWolf]

The issue was that the energy required to remove the water from the tanks required more energy than is produced. They try to compensate by using solar energy and wind energy but those require certain conditions that arent always present. My idea incorporates a device that can be used 24/7 with an efficiency of up to 95%. I was just curious to know issues that others in the past may have faced so I can make adjustments.

[Sensei]

The issue was that the energy required to remove the water from the tanks required more energy than is produced.

That's not an issue. That's normal.

 

They try to compensate by using solar energy and wind energy but those require certain conditions that arent always present.

You misunderstood idea described in article.

It's meant to be storage facility, not regular power station.

Energy is produced elsewhere, and solar panels and windmills are example power stations that are periodically working.

Once they lost energy source (at night, or when there is no wind), energy is restored from storage and customer continuously receive energy.

 

My idea incorporates a device that can be used 24/7 with an efficiency of up to 95%.

I stay doubtful.

 

How did you calculate that your idea will be 95% efficient?

 

[LoneWolf]

The overall process isnt ~95% efficient, the process to remove the water from the tank is, depending on materials used.

[Endy0816]

They are pumping out water with Renewables and gaining some of that energy back whenever the sea water is allowed back in.

 

Pumping and air pressure are the typical solutions. If you have something better then by all means describe it. Likely though, many of the options have already been considered by the enginnering team.

 

Aside:

 

Interesting the new sorts of batteries being thought up. One I saw was based around using renewables to move a loaded rail car up a mountain and gaining energy back whenever it was allowed to come down. Another was using renewables to make fuel and gaining energy back during combustion.

Edited May 9, 2014 by Endy0816

[LoneWolf]

My thought was using electrolysis to turn the water to gases which would basically create a self powering electrolyser. Right?

[Enthalpy]

Anyway, the idea of removing water from a tank with external pressure is bad, because the tank must resist the pressure, and worse, external pressure, and this costs an awful lot to build.

 

Much more clever - and I believe economically viable - are Prof. Seamus Garvey's underwater bags

http://news.bbc.co.uk/2/hi/uk_news/england/nottinghamshire/7315059.stm

http://www.energyharvestingjournal.com/articles/compressed-air-energy-storage-00003358.asp?sessionid=1

which are being prototyped.

 

These have bags anchored at depth, which don't resist the pressure. They store air as a trapped bubble, pumped or turbined to store or recover energy.

 

If you compare both:

- For the save P*V, the evacuated tanks must resist the pressure, the bag not! Bags win, tanks lose.

- You get a bit more energy from an expanded gas, because its V increases when you exploit its P

- Proper heat exchangers can give the air the temperature of the Ocean's depth when you compress it, but of the Ocean's surface when you exploit the expansion.

 

I tried to put some technical and economic figures on the bags (and pumps and pipes and exchangers).

http://www.physforum.com/index.php?showtopic=21016&st=0 sorry for the mess

I believe these belong to the very few sensible methods - together with flywheels

http://www.scienceforums.net/topic/59338-flywheels-store-electricity-cheap-enough/

and just batteries (preferably of sodium instead of lithium if the Japanese university succeeds)

plus of course pumping between two lakes (already done, needs lakes)

and possibly the Belgian artificial ring island on shallow seabed, from which water is removed to store energy.

My thought was using electrolysis to turn the water to gases which would basically create a self powering electrolyser. Right?

 

"Self-powering" sounds like energy created from none, which doesn't exist.

As opposed, electrolyse water to store electricity, consume the gases in a fuel cell to restore it, that works. It's just that both transformations are inefficient, like 60% each. Such figures are a no-no in the electricity business.

Big water pumps and turbines achieve >>95% which is a more sensible figure. The flywheels must be the most efficient over few days.