back to article Harvard gives solar batteries performance-enhancing vitamins

Harvard University researchers reckon they can make flow batteries cheaper using an electrolyte based on vitamin B2. Flow batteries function much like lead-acid batteries, with a fluid that reacts with electrodes to store charge. However, the liquid is cycled through an external tank in the charge/discharge cycle. The …

  1. Anonymous Coward
    Anonymous Coward

    Electric cars

    Flow batteries would also be terrific for electric cars, as it means you can refuel as quickly as you do today: by replacing the fluid.

    The station could have a big reservoir underneath where fuel is kept today where it is recharged between fillups / overnight. This would avoid the need for high power grid connections for every station to support multiple simultaneous quick charges, or complicated equipment for automated battery swaps.

    1. Pascal Monett Silver badge

      Re: Electric cars

      I believe you've hit the proverbial nail on the head. I agree that electric cars using this kind of liquid battery would be a godsend.

      But I do not see that we'll avoid the need for high power grid connections. Solar and all renewables are limited in their production capacity, so a local array of panels is not necessarily going be enough when recharging the used fuel. There would be tankers, obviously, they could take away the used after delivering charged fuel. That way, the tankers would unload the depleted fuel at a recharging station with vast capacity. I guess that could be a solution. Not convinced that it would remove the need for local recharging though.

      1. Jimmy2Cows Silver badge
        Boffin

        Re: Electric cars

        I believe you've hit the proverbial nail on the head. I agree that electric cars using this kind of liquid battery would be a godsend.

        Sadly not so much... It all sounds great until you realise how genuinely crap the energy density of flow batteries is. And for cars, affordable high energy density is what matters (well, and power density if you want decent acceleration).

        You need a truly massive volume of electrolyte fluid to make up for the poor energy density. Which is obviously very heavy and makes it all kinda pointless. Would be like towing your own petrol tanker, except it'd be filled with electrolyte.

        Flow batteries advantage is they are cheap (relatively), simple, and have a virtually unlimited recharge cycle, and as has been said recharging them is as simple as changing the fluid. This makes them great for static applications like grid-scale storage as grid-scale applications are generally not limited by size, weight or volume. Cost is king!

        Sucks for transport applications. Like it or not, petrol is one of the most energy-dense, easily tranported, stored and transferred energy storage medium around.

        1. Anonymous Coward
          Anonymous Coward

          @Jimmy2Cows - flow battery energy density

          So how many gallons would be required for a 200 Kwh flow battery? From what you're saying, it sounds like way more than the 16 gallons of gasoline to provide the same. But on the other hand, if you get rid of the engine and transmission, you've got a lot of volume and weight to trade. Perhaps it doesn't work for passenger cars, what about trucks, buses and trains, where size and weight is less of a concern?

          EDIT: did a little googling and found a link for a flow battery that does 167 wh per litre. Assuming that's a typical figure, it rounds to about 0.6 kwh per gallon. So you'd need about 330 gallons to equal 200 kwh. That's a lot of weight/volume, but if you were willing to trade a bit of range (say 200-240 miles instead of 400-500 miles) you could drop that to 150 gallons. That seems feasible for a passenger car, and since you'd be able to fill up as quickly as you can now, reduced range is less an issue than it would be for a car that has to recharge.

      2. Dwarf

        Re: Electric cars

        @Pascal

        Replaceable fluids makes a lot of sense - after all we've been doing this with cars and lorries for decades !

        However, wouldn't the collection / delivery lorries at least halve the perceived benefits of electric cars ?.

        Having a fleet of other vehicles driving around swapping out their used fluids, even if they were electric vehicles (which is unlikely as they would have a long route to do), then you can at best halve the overall effectiveness (Greenness ?) of the cars.

        In addition, you would probably have to worry about handling charged materials and self-leakage would presumably be an issue too.

        On-site charging at the station seems to make most sense in my mind. Place it there once and possibly replace it when its no longer viable for holding charge etc. I assume they would also have to filter contaminants - given the way that some people approach the idea of car maintenance.

        1. Pascal Monett Silver badge

          Interesting points

          The use of fossil fuels in our civilizations stems directly from the sheer amount of energy they contain. I have always been convinced that, however we get to electric cars, we will never see electric construction vehicles - or planes, for that matter. Fossil fuel is a must when you need 500HP to lug twenty tons of rock around. Or else we've found Star Wars technology, in which case I accept defeat most graciously.

          @Jimmy2Cows : after a bit of googling, I must admit that your point is unfortunately quite valid. Kind of puts to rest the entire notion for vehicular transport. Sad.

          @Dwarf : the "greenness" of cars would anyways be impacted by the global aversion the human population has for nuclear power. It serves nothing to have electric vehicles if their recharging is done with coal plants. And nobody raises the issue of the toxic components of the batteries themselves.

          That said, I doubt "charged" liquids would be any more of a hazard than the current incendiary liquids we use now. Plus, there would likely be less dangerous vapors to content with, so the refilling could be done in an airtight environment without much trouble.

          Of course, the idea of plugging in your car and having nano-carbon batteries replenished in mere seconds would be nice, but then we're back at the high power grid connections issue we started with, and no change in the energy generation problem.

          It seems to be a big mess in any case.

          1. Anonymous Coward
            Anonymous Coward

            Re: Interesting points

            This link may be of interest

            http://www.gizmag.com/quant-e-sportlimousine-flow-cell/31006/

            It looks a little to good to be true but there are multiple articles

      3. Anonymous Coward
        Anonymous Coward

        @Pascal - high power grid connections

        I didn't mean to imply the stations wouldn't need grid connections, but the size of the grid connection is quite different in terms of what you'd need to be able to simultaneously quick charge a dozen cars at once during peak times (i.e. rush hour when everyone is stopping to fill up) versus what you'd need to be constantly charging your "used fuel" 24x7. If you have 150 people through the station in a day, you only need to charge about six cars per hour. In reality you may get more than 150 cars in a day in many stations, but they aren't all empty, either.

        There is around 33 Kwh per gallon of gas. If you assume a gasoline engine is 38% efficient (which would be pretty good) and there are 16 gallons in a tank that's about 200 Kwh in a tankful. So you need to deliver about 1200 Kwh per hour to recharge 150 cars a day from zero. That's a pretty big grid connection, but doable.

        It isn't that a station would have solar panels, you'd need acres to generate 1.2 Mw and that's only during the day. But if houses and buildings all over had solar panels, and generated more than they needed, that power needs to go somewhere. Too much solar could be a problem for grids today, unless that power has somewhere to go. If gas stations will take as much as you can produce, they're a sink for all that excess power and avoid problems with the grid. They can even help the grid in the other direction, by reducing/eliminating their load during peak periods, or theoretically even pushing power back into the grid.

  2. gregthecanuck
    Trollface

    Oh no, not again

    OK, I think it's time we came up with a new acronym for all these improved battery technology articles. I propose:

    - Yet Another Better Battery Article

    - Describes Amazing Breakthroughs Beyond Assumptions

    - Droning On and On

    Yup, it's YABBA DABBA DOO!

  3. kmac499

    Flow Cells seem like a good alternative to the Tesla Powerwall devices. The ability to have the amount of Energy stored completely independent of the Power the unit can produce, seems perfect for home use.

    Most of the time a house only needs a few hundred or a couple of kilowatts for it's 'Baseload'

    Big Tanks are cheap and the domestic fuel cell and inverters can be kept quite small and easy to mass produce.

    1. Fred Flintstone Gold badge

      I think the main importance here is the ability to store excess generated energy to cover peak usage, a main issue with solar and wind energy.

      Interesting development indeed. I just hope it doesn't vanish quietly like so many of these other breakthroughs..

  4. Bob Rocket

    if it's electrolytes they want

    They should be using Brawndo instead.

  5. Sureo

    "...alloxazine, which forms the backbone of how the vitamin stores energy in human bodies."

    Conjures up images of human bodies in tanks generating power, ala Matrix.

  6. Anonymous Coward
    Anonymous Coward

    DIY

    I'm thinking electric bike batteries here, the storage does not need to be in one area and everything can be connected together with pairs of hoses.

    Way safer than a conventional battery and if one tank breaks you lose capacity but not the whole pack if it is properly designed with valves etc.

  7. Kevin McMurtrie Silver badge

    Lead-acid not flow

    Lead-acid batteries are not flow batteries. Power is created by sulfuric acid taking oxygen off the positive plates and creating lead sulfate on both plates. Both plates become inert lead sulfate so adding fresh acid doesn't add power. (Except for some exotic experimental designs that move dissolved lead)

  8. Anonymous Coward
    Anonymous Coward

    please clarify...

    Article says: "...lead acid batteries have to be kept above 50 per cent charge..." so does that mean their quoted capacity is double their practical real-world capacity?

  9. Conundrum1885

    Re.please clarify

    The 50 percent rule is due to the irreversible (without clever tricks involving woowoo and mouse milk) loss of capacity due to the formation of hard sulphate rather than the regular soft kind.

    To add insult to injury the hard kind tends to eventually deform the separators which permanently and irreversibly shorts the cell(s). as well as bending the plates and other "Fun Stuff" (tm)

    I did find a fix for motorcycle batteries of the flooded variety, it seems that sometimes slow charging over very long periods can undo most of the damage as long as you check the fluid levels regularly and limit charge current to 1A for a 10Ah battery.

    Maybe its the combination of 8-10 hours charging and overnight rest that does it because every battery has come back to life so far and hydrometer+voltage check shows good to excellent retention.

    Caveat: if some fool has filled up a cell with water or worse, vinegar to "fix" it or it has an obvious burn mark halfway down the battery then it needs recycling because no amount of charging is going to fix that.

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