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Power Science

Rivers Could Generate 2,000 Nuclear Power Plants Worth of Energy With 'Blue' Membrane (sciencemag.org) 129

Posted by BeauHD from the turning-blue dept.
sciencehabit shares a report from Science Magazine: Green energy advocates may soon be turning blue. A new membrane could unlock the potential of 'blue energy,' which uses chemical differences between fresh- and saltwater to generate electricity. If researchers can scale up the postage stamp -- size membrane in an affordable fashion, it could provide carbon-free power to millions of people in coastal nations where freshwater rivers meet the sea. Blue energy's promise stems from its scale: Rivers dump some 37,000 cubic kilometers of freshwater into the oceans every year. This intersection between fresh- and saltwater creates the potential to generate lots of electricity -- 2.6 terawatts, according to one recent estimate, roughly the amount that can be generated by 2,000 nuclear power plants. By pumping positive ions to the other side of a semipermeable membrane, researchers can create two pools of water: one with a positive charge, and one with a negative charge. If they then dunk electrodes in the pools and connect them with a wire, electrons will flow from the negatively charged to the positively charged side, generating electricity.
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Rivers Could Generate 2,000 Nuclear Power Plants Worth of Energy With 'Blue' Membrane More

Rivers Could Generate 2,000 Nuclear Power Plants Worth of Energy With 'Blue' Membrane

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  • Great Idea (Score:4, Insightful)

    by NicknameUnavailable ( 4134147 ) on Wednesday December 04, 2019 @09:26PM (#59486284)
    Kill of brine ecosystems to "save the planet." Bonus: you get to blame global warming for the inevitable die-offs and get grant money.
    • This. What is the chemistry of side effects that happens when any current flows? Would it make the water more acidic, more alkali?

    • Re: (Score:2)

      by PPH ( 736903 )

      This.

      And if there's a fish and an Indian tribe involved, kiss that idea goodbye.

    • Re:Great Idea (Score:5, Interesting)

      by vivian ( 156520 ) on Wednesday December 04, 2019 @10:01PM (#59486410)

      It would be interesting to know if this can work on differing levels of brine - ie. concentrated salt water from RO plants, getting diluted to normal sea water salinity.

      RO plants need to pressurise sea waster to very high pressure to push the water molecules through a semi permeable membrane, resulting in a fresh water stream and concentrated salt water (brine) stream.

      ie. currently in SWRO, sea water brine + high pressure (approx 600 psi, lots of energy) + RO membrabe -> concentrated brine (waste)+ fresh water. (product)

      large scale RO plants also use a hydraulic turbine that uses excess pressure at the membrane brine outlet side (waste) to help with compression on the inlet side, which makes this process more efficient - recovering some of the energy required to get to the high pressures needed for RO.

      There would also be an osmotic pressure differential between the concentrated brine and normal sea water which it is usually dumped into, so a device like this should also be able to help recover some of the waste energy, similar to what the turbine does for pressure recovery.

    • Re:Great Idea (Score:4, Insightful)

      by AK Marc ( 707885 ) on Wednesday December 04, 2019 @10:24PM (#59486470)
      Came here to say this. Maybe some small applications at parts of the transition, but the large use would destroy ecosystems.

    • Re:Great Idea (Score:5, Insightful)

      by Baloroth ( 2370816 ) on Thursday December 05, 2019 @01:08AM (#59486664)

      Why would it kill off brine ecosystems? The fresh and saltwater still end up mixing just as they would without the membrane. All this does is harvest the energy potential created from that mixing process. Of course there's going to be issues with animals and plants that live near the boundary getting caught in the membrane, and you have to make sure alterations to the river flow don't disturb things like nutrient delivery, but those are technical problems, not fundamental ones. Maybe they're unsolvable in some cases, maybe not. All this is is basic research to establish if the technology is even possible, not that it's practical or a good idea.

      • You don't have to damn the river for this, you just divert some of the flow into a pool near the river mouth, and draw in some of the seawater for your other pool. Like any development, this would disrupt the ecosystem in the spot where you build it but otherwise... Well, let's see. If you diverted a great deal of the river flow then it would impact the ecosystem right at the mouth of the river. Coral usually grows in those places, living off of the nutrients that the river brings downstream.

        Ultimately,

  • Impressive (Score:3, Insightful)

    by 110010001000 ( 697113 ) on Wednesday December 04, 2019 @09:29PM (#59486300) Homepage Journal

    Blue Energy has been around for a while, but this seems like it made it a heck of a lot more efficient. I can't imagine this would be so great for the wildlife though.

  • Thin film solar cells? Anyone? (Score:3)

    by thesjaakspoiler ( 4782965 ) on Wednesday December 04, 2019 @10:11PM (#59486434)

    What happened to the promise of thin film solar cells on a roll for a $1 per meter ?
    All these lab experiments never seem to work in real life.

    • Re:Thin film solar cells? Anyone? (Score:5, Informative)

      by AmiMoJo ( 196126 ) on Thursday December 05, 2019 @06:45AM (#59487090) Homepage Journal

      Thin film solar currently accounts for around 9% of deployment. You can buy them retail for about $0.25/watt.

      They aren't more popular because they are less efficient so given the choice people tend to install more efficient rigid panels. There are situations where they are more suitable though which is the 9%.

      • They aren't more popular because they are less efficient so given the choice people tend to install more efficient rigid panels. There are situations where they are more suitable though which is the 9%.

        If it really costs $0.25/watt, then it is ALWAYS the better choice. A 4kw system for $1000 (peak draw from the electric company this year was 4.2KW, and I live near New Orleans) on every house, and you can shut down every coal plant and most of the natgas plants in the country....

        Note however, that a quick

        • Re: (Score:3)

          by AmiMoJo ( 196126 )

          $0.25/W is the retail price of the film, just check AliExpress for example. You need something to mount it on, support electronics, installation on top. It's good for special cases but for general domestic roof installations panels are cheaper and much easier to work with.

    • Sent from your iphone over a wireless global telecommunications network over fiber optics backed by satellites.

  • Great to power a digital clock at a science fair, but impractical to build the size necessary to power a city.

  • Next breakthrough: Potato batteries (Score:5, Funny)

    by 93 Escort Wagon ( 326346 ) on Wednesday December 04, 2019 @10:25PM (#59486474)

    I'm waiting for the next breakthrough - the one where they've rediscovered the Potato Battery [wikihow.com] and tell us all they have to do is figure out how to scale it up, then the state of Idaho will solve the world's energy needs.

  • Specifically, using a membrane to separate out methane from ass gas? Put poop in a big bag, capture gases, separate methane, burn for energy. How much could that produce?

  • Seriously, fish that depend on rivers to spawn just can't get a break.

    • Re: (Score:2)

      by quenda ( 644621 )

      Seriously, fish that depend on rivers to spawn just can't get a break.

      Hydroelectric power systems have solved that problem. So I'm sure it can be done here too.

  • This is solar power (Score:3)

    by Solandri ( 704621 ) on Thursday December 05, 2019 @01:38AM (#59486702)
    This is solar power. Except instead of covering a surface with manufactured PV panels to collect it, you're using the surface area of all the oceans on the planet as your solar collector. The water evaporates, leaving the salts behind, creating a slight energy gradient between fresh and salt water. Same goes for hydroelectric power, where the evaporated water rising in the air due to being heated by sunlight picks up potential energy, which it releases when it falls as rain and flows downhill. Likewise for wind power. Winds are caused by thermal gradients created by uneven heating of the land and sea by sunlight.

    The problem with solar power is that its very diffuse. It takes enormous infrastructure to collect a very small amount of power. Sunlight at noon hits the Earth at around 750 W/m^2. Multiply by the ~20% efficiency of PV panels, and the 0.145 average capacity factor for latitudes near the U.S. (takes into account night, weather, angle of the sun as it moves through the sky, etc) and those PV panels will only generate an average of a measly 22 W/m^2 over a year. Most of the "advances" in powering things with solar hasn't been due to improving PV panel efficiency (which has gone from about 10% to 20% in 45 years). It's been due to reducing the electricity consumed by our electronics and lights (100 Watts for an incandescent bulb in 1975 to about 10 Watts for an LED light today).

    While direct sunlight-to-electricity is needed in some situations (e.g. the electronics and radio in mountaintop weather monitoring stations), you always need to check if it really makes sense to collect solar energy with expensive solar panels, or if other methods which rely on natural solar energy collection might be cheaper and make more sense (if less glamorous). Fundamentally, burning wood is also using solar power. The tree collects sunlight, and uses photosynthesis to store that captured solar energy in wood. Over the years, it concentrates an enormous amount of collected solar energy in a small amount of wood. When you chop down a tree and burn the wood, you are releasing that trapped solar energy.

    • 22W/m^2 is well below what people were getting from RV-top arrays even 30 years ago.

    • Re: (Score:2)

      by AmiMoJo ( 196126 )

      The main advantage of PV over other types of solar is how easy it is to install. If you have a roof you can probably put solar panels on it and wire them in easily enough, and over time they will pay for themselves and then generate profit.

      • Re: (Score:2)

        by kenh ( 9056 )

        and over time they will pay for themselves and then generate profit.

        With or without government subsidies and mandated purchase agreements from utilities?

        The minute the solar industry can demonstrate cheap solar energy without relying on government grants for basic research, tax incentives to build factories, government grants to train installers, government subsidies to purchase panels, and mandatory excess energy purchase by utilities at above market rate I'll happily celebrate the achievement, but until then it's no where near break-even,let alone profitable.

        • Re: (Score:2)

          by AmiMoJo ( 196126 )

          Without subsidies. Solar has been cheap enough to pay for itself subsidy free for getting on 20 years. It's just a question of having the up-front cash and being able to wait for the payback, which is getting faster all the time.

          • Re: (Score:2)

            by hawkfish ( 8978 )

            Without subsidies. Solar has been cheap enough to pay for itself subsidy free for getting on 20 years. It's just a question of having the up-front cash and being able to wait for the payback, which is getting faster all the time.

            There are hidden subsidies in the form of externalised costs [www.welt.de]:

            The researchers had investigated whether the pollutants used in the four main photovoltaic technologies are water-soluble. Contrary to previous assumptions, the result shows that pollutants such as lead or carcinogenic cadmium can be almost completely washed out of the fragments of solar modules over a period of several months, for example by rainwater.

            They are starting to recycle panels in Europe [solarpower...online.com], but the costs are not zero [solarindustrymag.com]:

            The costs imposed on t

    • Re: (Score:2)

      by necro81 ( 917438 )

      This is solar power.

      Something like 99% of the energy flow through planet Earth comes from the sun. The remaining 1% is geothermal and tidal.

    • Re: (Score:2)

      by urusan ( 1755332 )

      Fundamentally, burning wood is also using solar power. The tree collects sunlight, and uses photosynthesis to store that captured solar energy in wood. Over the years, it concentrates an enormous amount of collected solar energy in a small amount of wood. When you chop down a tree and burn the wood, you are releasing that trapped solar energy.

      Using this logic, burning coal and oil is also solar energy.

      If anything, you're making an excellent argument that this new energy technology could work, because it is focusing the diffuse solar power into the relatively thin interface between rivers and oceans.

  • This looks like one of those profit-over-common-sense ideas again, that will ruin a whole type of ecosystem.

    We have a freakin' fusion reactor in the sky!! What's wrong with you?!
    And wind everywhere there is no sun.
    And HVDC lines. And trivial covered pumped-storage hydroelectricity tech.
    Hell, you can even use synthetic gasoline in fuel cells that is infinitely recyclable using abovementioned fusion reactor, is clean and has energy densities no battery will ever achieve.

    Come on. Stop the silly shit. We've so

    • Pumped storage is hardly trivial. It has very specific terrain requirements, and while the running costs are low the capital costs are enormous.

  • Great idea guys, but it's more than 10 years away from being viable from an industrial perspective, don't you think? Can we invest a bit more in the Fusion idea please and spend some money on some new nuclear power plants in the meantime?

    If the idea is to remove dependency on fossil fuels, then why are we not out demanding more nuclear power capacity NOW? Why do we have to keep arguing "Well this new promising technology (which is a decade away from being helpful) can replace huge numbers of nuclear pla

  • Another very early result with absolutely no information about scalabillity and price. If you ignore these, there are a lot of technologies that can do amazing things. Unfortunately, they are completely irrelevant in standard situations.

  • And this isn't a flame, so don't take it as that.

    But hydroelectricity is one of the greenest ways of generating electricity and has been used for ever. But the disruption to wild life is one of the reasons that it is no longer preferred. Among a number of reasons is is no longer prefered.

    In 2013, French researchers made just such a membrane. They used a ceramic film of silicon nitrideâ"commonly used in industry for electronics, cutting tools, and other usesâ"pierced by a single pore lined with

  • Didn't we learn anything when hydro dams were built that blocked waterways and decimated wildlife populations?

    Wildlife isn't going to get through ion exchange membranes.

  • They use " chemical differences between fresh- and saltwater to generate electricity." The biggest issue I see is that there normally aren't pristine freshwater rivers that dump into the ocean. Admittedly, the article didn't say the fresh water needed to be pristine. Nonetheless, saltwater normally mixes with river water which can cause them to be brackish 100+ miles from the ocean. Its a gradual change. That would mean the differences between fresh and saltwater will be gradual as well. I'm sure the engine

  • Such a membrane will either be quickly torn apart or become clogged. Or become the food of some bacteria. Or become the attempted food of some critter.

    Such a plan will impact wildlife and the landscape negatively. If you're willing to do this, such a plan is fucking pointless because you can already use rivers to generate electricity, and much more of it, with things called dams.

    This will fail just like Solar Roadways and other such scams. I say it's a scam because the other option is that the people beh

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