Harvesting Power When Freshwater Meets Salty 151
ckwu writes "As a way to generate renewable electricity, researchers have designed methods that harvest the energy released when fresh and saline water mix, such as when a river meets the sea. One such method is called pressure-retarded osmosis, where two streams of water, one saline and one fresh, meet in a cell divided by a semipermeable membrane. Osmosis drives the freshwater across the membrane to the saltier side, increasing the pressure in the saline solution. The system keeps this salty water pressurized and then releases the pressure to spin a turbine to generate electricity. Now a team at Yale University has created a prototype device that increases the power output of pressure-retarded osmosis by an order of magnitude. At a full-scale facility, the estimated cost of the electricity generated by such a system could be 20 to 30 cents per kWh, approaching the cost of other conventional renewable energy technologies."
Re:Big problem here... (Score:5, Insightful)
I know this will probably cause a host of issues that I'm not thinking here, but the (to me) most obvious solution would be to pair this with a de-salinization plant. What if instead of de-salinizing all the water they stop at X% of water remaining in the solution, and then use that super-concentraded saline water with the power generation plant.
Re:I pay 11 cents per kWh (Score:5, Insightful)
Unless maybe we stop subsidizing fossil fuels?
Re:I pay 11 cents per kWh (Score:5, Insightful)
Renewable is going nowhere until they're at parity.
No amount of greenwashing and tree hugging circlejerking will change the fundamental economics of this.
The problem here is you're not comparing apples to apples. The 'cost' of fossil fuels doesn't include environmental cleanup that isn't necessary with renewables. It also doesn't take into account the real cost - when you take out all the tax incentives for fossil fuels, the math becomes quite different.
Also, the cost of fossil fuels will continue to go up due to environmental laws and more difficult to process sources (like tar sands), fighting unnecessary wars to secure foreign oil sources; meanwhile, while the cost of renewable technology keeps going down.
Parsing the summary (Score:4, Insightful)
At a full-scale facility...
So, we're guessing about imagined economies of scale that may or may not, hypothetically speaking, materialize, in the best-case scenario of a fully-developed, mature technology, probably some decades hence.
...the estimated cost of the electricity generated by such a system could be 20 to 30 cents per kWh...
Our wild-assed guess ranges over a factor of 1.5 anyway.
...approaching the cost of other conventional renewable energy technologies.
"Approaching", in this instance, meaning "costing twice as much as" pholtovoltaic systems, which already sit at the expensive end of the renewable spectrum.
Continuous Flow (Score:4, Insightful)
Bad news for Mangroves (Score:2, Insightful)
The only thing they will do is to remove zones of brackish water from the environment, that are usually highly prized by greenies as having high biodiversity and such stuff. Of course this is all swept to the wayside once you can make "green energy" out of all this green stuff. You'll even find conspiracy theories thrown out by eco-nuts blaming "big oil" for preventing such "innovative alternative technology" from coming to market. If that should happen, very soon they will have an epiphany, realize that in fact those osmotic power plants destroy important ecological niches ... and by this point, of course, osmotic power plants are run by "big energy" without any respect for the environment. And of course, everybody in the green movement has always been against such a stupid idea.
How far fetched is this scenario ... look no farther than bio-ethanol.
Re:Big problem here... (Score:5, Insightful)
No, more like using electricity generated from your brakes to charge your battery and improve fuel economy. What a concept!