PowerSwitch Main Page
PowerSwitch
The UK's Peak Oil Discussion Forum & Community
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Electricity from mixing sea and river water

 
Post new topic   Reply to topic    PowerSwitch Forum Index -> Other Alternatives
View previous topic :: View next topic  
Author Message
genoxy



Joined: 24 Nov 2005
Posts: 127
Location: London

PostPosted: Fri Dec 23, 2005 3:07 am    Post subject: Electricity from mixing sea and river water Reply with quote

Quote:


LEEUWARDEN, Netherlands (Reuters) - "Water will be the coal of the future," French science-fiction writer Jules Verne predicted in 1874.
More than a century later in a world seeking clean alternatives to fossil fuels, Dutch and Norwegian scientists believe they can help turn Verne's dream into reality.


Seems to me like an idea with great, though limited, potential. Would be interesting to read what some of you, who understand more than I do, have to say.

Link and article below:

http://news.yahoo.com/s/nm/20051216/lf_nm/energy_water_power_dc_1

Quote:


The Dutch Center for Sustainable Water Technology or Wetsus, and Norway's independent research organization SINTEF, working with power company Statkraft, have invented devices that generate electricity by mixing sea and river water.

It might seem like an exercise in scientific theory destined only for high-tech laboratories, but the process' creators and the European Union, which funds the Norwegian research, believe the idea's time might have come.

"There is huge potential in Europe to use this new way of producing electricity," Philippe Schild, scientific officer at the European Commission's energy directorate, told Reuters.

"It's a renewable source which does not cause any environmental damage and we think it can play a big role in helping meet our target to increase renewable energy," he said.

Global warming and high oil prices have renewed interest in sustainable energy, with solar, wind, biomass, hydrogen fuel cells, tidal and wave power getting most attention.

But researchers in Norway and the Netherlands, known for their water technology know-how, say there is room for other alternatives given the world's ever-growing appetite for energy.

WATER BATTERY AND HOTDOGS

The new devices are based on a natural process -- when a river runs into the ocean, a huge amount of energy is unleashed because of the difference in salt concentration.

"It's basically harvesting the energy that comes free from a natural process," Wetsus managing director Johannes Boonstra said in his agency's laboratory in the Dutch town of Leeuwarden.

"You have the fuel for free and it's very sustainable -- no greenhouse gas emissions."

The two projects use different methods to harness the electricity -- the Dutch apply something called reverse electrodialysis while the Norwegians use a kind of osmosis.

Both methods rely on membranes or thin films made of special material used for chemical separation. In the Dutch project, separation is done by membranes using an electrical current.

"It works like a water battery," Wetsus project manager Sybrand Metz said.

The Norwegian device applies pressure to force the water through membranes. Its inventors liken the process to putting a hot dog in hot water. The skin of the hotdog acts as a membrane, allowing more water in than the amount of salty water it lets out. This increases the pressure inside and the hotdog bursts.

The principle behind the Norwegian device is that fresh water and salt water are channeled into a membrane module. The fresh water is transported through the membranes and over into the pressurized sea water. The pressurized mixture of sea water and fresh water flows out of the module and into a hydropower turbine that generates electricity.

The two inventions, however, have still a long way to go before they can be applied commercially.

The Wetsus project, supported by a consortium of Dutch companies, has yet to be tested in a pilot plant. The Norwegian project is more advanced. It started in the 1990s and its creators have already installed two small-scale plants, but have yet to build a bigger demonstration plant to boost production.

TOO EXPENSIVE

Like other alternative energy technologies, cost is the biggest hurdle. Power produced by mixing sea with river water is several times more expensive than wind or solar energy.

The idea of producing electricity from salt and fresh water was first explored during the energy crisis of the 1970s, but membrane technology was not sufficiently advanced and scientists dismissed the process as hopelessly expensive.

The membrane industry has matured since then and is now widely used in water and pollution treatment, power generation, production of medical, biotech and electronics devices.

The main challenge is finding membranes that are efficient and robust enough to boost production, but also cheap.

"We have to be competitive with electricity from coal or gas," Boonstra said. The scientists believe it will take at least 5 years to develop cheaper membranes, test them and be able to put the project on the market.

Norwegian project manager Rolf Jarle Aaberg believes power-from-water will be ready to seriously challenge other renewable energy technologies between 2010 and 2015.

The new power plants can be built wherever fresh water meets salt water, such as the outlets from existing hydroelectric power stations, and could even be placed underground.

Statkraft and the European Commission put the production potential in Europe at 200 terawatt hours a year, or nearly twice the electricity consumption of a country like Norway.

The potential in Norway alone is estimated at 10 percent of its annual power needs. The river Rhine, for instance, could deliver 3,000 megawatts of power where it flows into the sea in the Netherlands -- the equivalent of five big coal-fired plants.

The new technique has attracted some skepticism, the scientists say, but they find comfort in history.

"When the first wind energy turbine was installed in Germany in 1985, the whole industry laughed," said Frank Neumann of the International Energy Agency's ocean energy program.

"It was a big failure then and millions were lost. But look at it now and how fast wind energy is expanding."

_________________
They say an intelligent person knows how to solve problems that a wise person would know how to avoid... Think about it in the context of our society for a moment Wink
Back to top
View user's profile Send private message Visit poster's website
mikepepler
Site Admin


Joined: 24 Nov 2005
Posts: 2863
Location: Rye, UK

PostPosted: Fri Dec 23, 2005 9:29 am    Post subject: Reply with quote

The membrane idea is real enough - desalination plants based on "reverse osmosis" use it, though they pressurise the water with a pump to get it to work. However, I can't quite believe there would really be enough pressure created from the process happening passively to run a turbine. Note that they also say it is several times more expensive than existing renewable power sources - so what about its EROEI?

I'm all for scientists/engineers researching new things like this, but I kind of think the rest of us should just get on and install the renewable generation technologies which we already have. We don't need to wait for a breakthrough of some sort, solar panels (thermal & PV), wind turbines, biomass and tidal schemes all work right now!
_________________
Mike

"Deal with reality or reality will deal with you"
Dr Colin Campbell

http://peplers.blogspot.com
http://peakoilupdate.blogspot.com
Back to top
View user's profile Send private message Visit poster's website
genoxy



Joined: 24 Nov 2005
Posts: 127
Location: London

PostPosted: Fri Dec 23, 2005 2:45 pm    Post subject: Reply with quote

mikepepler wrote:
The membrane idea is real enough - desalination plants based on "reverse osmosis" use it, though they pressurise the water with a pump to get it to work.


Exactly what had intrigued me most - how much energy goes into the process(?)
mikepepler wrote:
However, I can't quite believe there would really be enough pressure created from the process happening passively to run a turbine.


Could this be the reason they say it has great potential only where rivers meet the sea? Presumably there it has enough volume to create substantial amounts of energy?

mikepepler wrote:
Note that they also say it is several times more expensive than existing renewable power sources - so what about its EROEI?


True, though they seem to blame it on the price of the membrane, and I have to say it doesn't sound too reliable - can a price of a single item in the system, make the whole process so expensive?

mikepepler wrote:
I'm all for scientists/engineers researching new things like this, but I kind of think the rest of us should just get on and install the renewable generation technologies which we already have. We don't need to wait for a breakthrough of some sort, solar panels (thermal & PV), wind turbines, biomass and tidal schemes all work right now!


Completely agree with you.

Also thanks for giving me a better insight there - much appreciated.
_________________
They say an intelligent person knows how to solve problems that a wise person would know how to avoid... Think about it in the context of our society for a moment Wink
Back to top
View user's profile Send private message Visit poster's website
Cycloloco



Joined: 24 Nov 2005
Posts: 192
Location: London, UK.

PostPosted: Mon Sep 21, 2009 12:52 am    Post subject: Re: Electricity from mixing sea and river water Reply with quote

genoxy wrote:
Quote:


LEEUWARDEN, Netherlands (Reuters) - "Water will be the coal of the future," French science-fiction writer Jules Verne predicted in 1874.
More than a century later in a world seeking clean alternatives to fossil fuels, Dutch and Norwegian scientists believe they can help turn Verne's dream into reality.


Seems to me like an idea with great, though limited, potential. Would be interesting to read what some of you, who understand more than I do, have to say.

Link and article below:....
[cut]


For the latest summary of progress, see:
http://www.rsc.org/chemistryworld/Issues/2009/September/ColumnThecrucible.asp

It is difficult to work out what this process is called and there is no mention of EROEI.
However, providing, for example, up to 10% of Norway's power needs is quite a lot of potential.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    PowerSwitch Forum Index -> Other Alternatives All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group