Weird Energy Storage Solutions Could Help The Grid Go Renewable

We’re all familiar with batteries. Whether we’re talking about disposable AAs in the TV remote, or giant facilities full of rechargeable cells to store power for the grid, they’re a part of our daily lives and well understood.

However, new technologies for storing energy are on the horizon for grid storage purposes, and they’re very different from the regular batteries we’re used to. These technologies are key to making the most out of renewable energy sources like solar and wind power that aren’t available all the time. Let’s take a look at some of these ideas, and how they radically change what we think of as a “battery.”

Iron Flow Batteries

Diagram indicating the operation of an iron flow battery. Credit: ESS, Inc, YouTube

Normally, the batteries we use consist of a metal or plastic case with some electrolyte inside, sandwiched between electrodes. Usually, the electrolyte is in a paste or gel form and for all intents and purposes, we think of batteries as a typically solid object, even if they’re gooey inside.

Iron flow batteries work in an altogether different fashion. They use liquid electrolyte that is pumped into a battery as needed to generate electricity. The electrolyte consists of iron ions in solution, typically in the form of aqueous solutions like iron chloride or iron sulfate.

Typical electrode materials are carbon for both the positive and negative sides, with the battery constructed as two half cells with a porous separator in between. As the battery is charged, the iron (II) ions are oxidized in the positive half-cell, giving up electrons to become iron (III) ions. In the negative half-cell, the iron (II) ions gain electrons to become iron (0), with the metallic iron plating on to the negative electrode itself. When the battery is discharged into a load, these reactions run in reverse, with the metal on the negative half-cell electrode returning to solution.

ESS has developed iron flow batteries that can fit inside shipping containers. This model can deliver 50 kW of power, and stores up to 400 kWh of energy. Credit: ESS, Inc., YouTube

Iron flow batteries have the benefit that they scale. Larger tanks and larger cells can easily be built, which is ideal for grid applications where there is a desire to store many megawatt-hours of energy. Of further benefit is the cycle life of an iron flow battery, measured anywhere from 10,000 to 20,000 cycles. That’s an order of magnitude better than most lithium-ion cells, and gives iron flow batteries a working lifetime on the order of 10 to 20 years, or even longer.

The chemicals involved are also cheap and readily available – iron and its salts being easy to source almost anywhere in the world. There is little requirement for the fancy rare-earth metals that are key to the production of high-end lithium-ion cells. Plus, the chemicals used are also safe – there’s not really anything in a iron flow battery that can explode or catch fire like other technologies.

The iron flow battery does come with some drawbacks, though. The technology simply doesn’t have the power density of lithium-ion batteries, so more space is required to build a battery capable of delivering the same power. Additionally, due to the plating reaction on the negative electrode, the iron flow battery doesn’t scale as well as some other theoretical designs. Other flow batteries only require more electrolyte to keep producing energy, with the size of the electrodes unimportant in this regard. Furthermore, while the technology stores electrical energy directly in a chemical sense, iron flow batteries are still typically less efficient than hydroelectric pumped storage, assuming suitable land is available. Advanced hydroelectric storage methods can counter this requirement, however.

Companies are developing the technology for real-world applications today. Shipping-container sized flow batteries from companies like ESS are available with capacities up to 500 kWh, with power outputs high enough to power tens of houses over a 12 hour period. Stacking multiple units into a single installation scales the capacity as needed. They’re aimed at the so-called “long term” storage market, for storing energy on the order of 4 to 24 hours. This makes them ideal for use cases like storing energy during daily solar peaks for use in the dark night time hours.

Carbon Dioxide Storage

A diagram indicating how Energy Dome’s storage facility works in charge and discharge cycles. Credit: Energy Dome, YouTube

Carbon dioxide is all around us, as a key component of the atmosphere. It’s also a gas that can readily be stored as a liquid at ambient temperature, as long as you put it under enough pressure. In this form, it takes up far less space, and there’s energy to be gained in the phase transition, too. Energy Dome is a company that identified that this property could be useful, and has developed a storage system based on the prevalent gas.

To charge the carbon dioxide “battery,” energy is applied to compress the gaseous CO2 into a liquid. The heat generated in the compression process is stored in a thermal energy storage system. To extract power, the liquid CO2 is warmed from the formerly stored heat, and allowed to expand through a turbine, which generates power. The design uses CO2 in a sealed system. The energy is stored in the pressure applied to the CO2 and in the phase change, rather than in any chemical reaction. Thus, it’s not really a “battery,” per se, any more so than hydroelectric pumped storage, but it is an energy storage system.

The system has the benefit of being constructed from simple, well-understood equipment that is already readily available. There’s nothing radical about compressing gases nor expanding them through turbines, after all. Plus, there’s no need for expensive rare earth materials or even large amounts of copper wiring, as with lithium-ion battery storage solutions.

Energy Dome is already planning a commercial deployment in the US by 2024. It has already run tests at a scale of multiple megawatts, indicating the basic principle of the technology. The company has also secured an agreement to build a facility for the Italian energy company A2A, with a 200 MWh capacity and 20 MW power delivery.

Future Realities

The fact is that as grids around the world switch to more renewable energy solutions, there will be ever-greater demands to store that energy. Traditional solutions like hydroelectric pumped storage are still relevant, as are the major lithium-ion battery installations popping up all around the world.

However, different circumstances mean that other storage technologies can also find their own niche. In particular, those that rely on cheap, readily available materials will have an advantage, particularly given the geopolitical and supply chain issues faced today. Expect more new technologies to pop up in this space as storing renewable energy becomes a key part of our electricity grid in future.

122 thoughts on “Weird Energy Storage Solutions Could Help The Grid Go Renewable

      1. If you can’t get a truck with diesel you’ve got bigger problems – things like enemy Su-25s cruising around. Toying around with inefficient green energy built on tears of 3rd world children from Africa should be your last priority.

      1. With diesel generator the worst that can happen is a fuel leak or fire. Both can be managed easily. Container full of plutonium can chemically poision people and land, not to mention radiation.

    1. 50kw for 8 hours 25kw for 16 hours 12,5kw for 32 hours. Because its 400kw of storage in their container. MANY MANY MANY MANY HOURS of standby if just being maintenance charged.

      Now your 400-700kw contant power diesel generator GRUNT GRUNT GRUNT it only produces power constantly if its constantly sucking gas. A 400 KW diesel generator running 1/4 loads going to suck down 8.9 gallons of diesel an hour. So Youll probably just want to scale down to the 50kw the battery can produce and level the field. Thats still going to run you 1.7-3.5gallons of diesel per hour of operation depending on load. Too bad you couldnt run the diesel generator at its most efficient fuel to power ratio speed and just store the energy until you needed it somehow….like a bunch of batteries or something

    2. I work for a firm that containerises batteries and gensets

      you can get over a megwatt battery with transformer holding 30-60MWH of power in a 20 foot container.

      you can also get a diesel or gas genset over 1MW in a 20 foot, scaling with different container sizes and site configurations.

      there is a lot more power available from the old means than some of the solutions in the article, but in 10-20 years time when fossil fuel bans come in to effect i bet they’ll be much more energy dense than even what i’ve described

    3. A container full of batteries that delivers 50kW? That’s laughable. My company operates electric buses that can charge with 520kW so I assume that if you needed the power, you could discharge with double that. And the buses are about shipping container size – but with room for passengers as well. A shipping container full of batteries could easily deliver into the tens, if not hundreds of MW’s. But the battery and generator are different things: the first an energy storage (which will eventually run out and be useless until it is replenished by a generator, electrical feed line or a wind turbine) the second an energy converter (from chemical to electrical), which would need an attached energy storage (tank of diesel) or delivery (pipeline of natural gas) system.

      Depending on whether you need short bursts of high power or continuous steady current one, the other or both may be the best solution.

  1. Nuclear. Just do nuclear. Or else we’re all screwed. Enough fiddling around with this utter crap that will only waste our time and (even more) resources until it’s too late. Unborn generations will curse you

      1. If we stopt flying by one accident, you wouldn’t travel that far today.
        Just because something can go wrong with serious consequences doesn’t mean we should give up there.
        We had accidents and we survived them all . Stop the negative view on history.

        1. we had to take iod tablets for about a year, and had to avoid to eat certain foods in the region, for example mushrooms or wild pigs, some of them you still not supposed to eat today since they are considerd to be to high concentration of uranium even after 50 years and although the accident was more than 100miles away. You don’t die immiditly but the probabilty to get cancer is highly elevated for many many years.
          Never had to face consequences like that because of a solar panel on the neighbours roof only 50 meters away.

          1. @Midnight Glass is just sand in waiting…

            In many places in the world astonishingly common in the fields and meadows already – broken beer bottles, the glass of some long buried Roman building, that windshield on the tractor, the nearby building that blew up in a gas explosion etc…

            Its neither a major issue or a new one – you really need to get the new sharp rocky bits out of the area you can skim and sieve the surface layers to pull out all the big bits, and the little bits of just coarse sand really… Annoying, and almost approaching expensive to deep clean but nothing more. Compared to a nuclear accident, or the radioactive stuff floating around from combat use of nuclear material its trivial in every sense of the world to deal with. BUT NOTE I am not saying nuclear is something to avoid!

      2. so let’s see here:
        – a reactor design that nobody else used for power
        – *no* containment. None. 0. Every other nuke plant has it.
        – a rather poorly designed safety test that the reactor manufacturer refused to sanction
        – an even poorer execution of said test, breaking many reactor operation rules that begin with “do not…”
        – the absolute insanity of the Soviet Union and the way things were done there

        last but not least, every nuclear reactor is running critical, otherwise they would not make any power…

        A single widescale blackout that EU keeps dangerously closer and closer to because of retarded German energy policies will kill more people in a week then all nuclear accidents combined.

      3. when the first car crashed? When the first plane crashed? When the first levy or dyke failed? Where would humanity be if we gave up when we fail? Chernobyl had design flaws, theres strong evidence of materials provided during construction were below the standard they were specified in plans, and below the specs of the materials per invoice, Whether corruption and graft or foreign action is a question for conspiracists. Ultimately, experimental operation devations testing new protocols pushed it too far.

        As of May 2022 there were 439 nuclear reactors in operation in 30 countries around the world. Its been 36 years since Chernobyl. Its been 11 years since Fukushima. You can hardly blame nuclear technology for being susceptible to a 9.0 earthqualke just off the coast and a 6 minute long 40.5 m (133 ft) wall of water. Thats a bit beyond human engineering.

        We need to focus on cleaner more efficient forms of nuclear now that the production of weapons grade uranium and plutonium isnt guiding our energy decisions. We certainly dont need to abandon nuclear tech because there have been a few accidents in its history.

      4. Have you looked into how and why the Chernobyl event happened? It wasn’t just because it was nuclear. It was mismanagement, completely avoidable while still keeping nuclear power. So was Three Mile Island. Fukushimi… well.. ending nuclear in geographically unstable environments such as tsunami prone beaches would be fine by me.

      5. You mean we should be beholden to the actions of the Soviets, where they bypassed safety after safety to perform an experiment, on a reactor without a containment building.

        To me support of Nuclear power is a true litmus test on if you actually believe climate change is a threat, or just a vehicle for “social justice.”

    1. Unfortunately, nuclear has been demonized and people will do anything just to halt or even just slow down new nuclear installations. However, like nature, you shouldn’t put all your eggs in one basket. Instead, we should take the Darwinian approach push every non-polluting energy system. Which every one works best then be pushed even more while the others die out.

    2. These technologies are not a replacement for any type of power generation (except for peaking plants) but rather to complement them. Nuclear does really well for providing base load power but it is not great at adapting to fast changing power loads. Grid scale energy storage can greatly increase the stability of the grid by providing power for short term peaks.

      1. Yep. only stability, which means we ‘still’ need that ‘steady’ always available power (base load) which the left and the green brain-washed continues to ignore. Nuclear can provide the base load, or coal, natural gas, etc. Basically our ‘natural’ resources.

        1. The other side of the coin being – what do we _actually_need_ to be included in base load = always on?

          Some demand-based consumption and billing is now technically feasible, and being trialed in the UK and probably elsewhere too.

          So – when the wind blows, you do your washing, aluminium smelting, whatever.

          1. @Jonathan Wilson Not really, the really giant operations you certainly don’t want to cool down and then have to reheat all the time. However there are both many scales of these sort of works from the small jewelry casting mob where a melt takes no time at all despite starting from cold to the real giants and even the giants have hopefully planned downtimes to refurbish their facilities.

            They just need enough of a projection of price/availably ahead to schedule their works (and to spend time developing the best methods to manage a new way of working around the power availability – which probably involves extra shifts and scheduling the melts for when the renewable spikes high so prices are really really low and more minimal smelting operations much of the rest of the time – still lots of prep for the next mad rush when the melting is cheap…).

            I do agree its not the lowest hanging fruit for demand scaling, that is in short order likely to be the EV – for most folks it doesn’t actually need more than a few percent of its battery each day anyway so a few hours, perhaps even a few days where the EV chargers are slow/expensive will start to really add up as the EV becomes more common. Plus currently to my knowledge most big metal smelters are not primarily electric anyway, so the electric availablity/price only matters as the same fuel you want is potentially in demand to top up the grid.

      2. Actually nuclear can easily be designed to handle rapid changes in power. It does exactly that in naval nuclear propulsion applications. Current commercial power plants typically are not designed for rapid power changes because there was no economic reason to do so.

        1. IIRC Diablo Canyon was originally designed to load follow.

          When they tried, many things broke and it only served to increase the power costs. Costs for a nuke plant being 99% fixed it just makes economic sense to run it balls out.

      3. Alternatively. Since nuclear is greener then even solar/wind we could just generate excess energy as the base load. Who cares if we throw away 10% of our energy as excess if it’s all beautiful clean nuclear power. Oh no we might have less brown outs god someone think of the children!

        1. Nuclear is great, but greener than renewables, especially solar is probably pushing it – A solar panel avoiding physical damage works practically forever, and the modern ones don’t degrade in output over time much either. Nuclear reactor have a definitive shelf life after which it’s build a whole new reactor, waste you do have to reprocess and/or store for quite some time and need a pretty substantial material investment in the first place – all that concrete is not cheap environmentally.

          There is also a hard limit on just how much Uranium can be sourced – at some point we either need to master making our own pocket sized stars for a net energy gain or rely on the Sun, so existing nuclear power is something akin to kicking the cans down the road, but you did pick up the paper for recycling…

          1. That is very arguable Dude – the waste disposal locations and nuclear stations are rather huge and very very specific infrastructure projects that are entirely accountable for the cost to create – where solar can largely just be a panel attached to existing stuff, the same is true for wind to some extent, and the other renewables are generally just one power station location that needs less material than the equivalent nuclear station upfront and has no need for a massive waste store afterwards.

          2. The new fast breeder reactors do not have the safety problems of older designs and use solid fuel waste as their fuel source. People call out the problems with older reactor designs as if there aren’t technical solutions already developed.

          3. Fast breeder still do have waste, and yes safety of new reactors is good. Doesn’t mean there is unlimited fuel or not enviromental cost to build them.

            I’m all for Nuclear, but not blind to its costs either.

        2. Just give away “excess” electricity produced off peak and that will incentivize end users to install batteries to reduce peak usage costs and make electric vehicles charged off peak even more attractive. Multiple other benefits too. Less peak load on grid, local backup, no dependence on wind or solar, etc.

      4. I don’t know much about current reactor or power plant design, but I don’t see why a plant couldn’t be designed to be adaptable to changing loads. Since they are essentially steam plants, could you not simply divide the generated steam among many, smaller turbine generators, which could start and stop quickly to match load? It might not be perfect, but it would likely make the more agile grid-scale storage systems easier and cheaper to implement.
        You could even implement heat storage to allow more turbines to operate while the reactor output is ramped up for the larger demand peaks.
        It seems like this would also help with maintenance, since generators could be taken completely offline during expected low-demand periods.

        1. Back EMF, phase mismatch, transient spikes, and losses due to spin up are the usual reasons. However, the use of energy storage would make these a nonissue; leading to the pursuit of storage tech in the first place.

    3. Centralized, highly vulnerable power generation in a world affected by war, social unrest and climate change. Producing fission-grade material as a byproduct. And way more expensive than renewables.

  2. The Iron Redox Flow Battery looks promising. It’s real downside is the 70% max round trip efficiency but if it’s cheap enough then that’s a non-issue. However, it’s waaay cheaper than hydroelectric fantasies which also require multi-year of environmental impact studies.

    1. Hey, it’s more than 50%!

      But really, something like that being used to fill in peak loads, while paired with abundant nuclear base power sounds really promising.

      Who cares if it’s not super efficient. Lots of things are wasteful, and it’s much better than alternatives!

    2. If that Iron Flow battery really only delivers 400kWh from that entire shipping container, then it’s dead on arrival. That is a small amount of power from a huge volume with very low efficiency.

      1. 400kWh ain’t a small amount of power, sure its no pocket nuclear powerstation but still that goes a long way, and the peak draw it can apparently supply is very impressive for a device seemingly so easily moved and deployed where you need it. Pretty sure the Ukrainians right now would love a few hundred of them.

        The efficiency also seems respectable enough to me, not great don’t get me wrong, but far from terrible and seemingly quite a cheap system to build and deploy at scale – which is something most energy storage methods can’t claim. Those more efficient are either massively more expensive, limited by geography or raw material processing/availability.

        1. It’s four Tesla batteries in 100x the volume.

          To have any real effect on the grid, we’re talking gigawatt-hour scale, and that means thousands of these things just to begin with.

          1. All down to how and where you are using it – but out in the middle of the Aussie outback dumping a few thousand times the volume of these things wouldn’t really be noticed, even by the Aboriginal. Same is true for lots of the USA and Canada. Heck many farmers could add one or two of these to their existing pile of shipping container storage boxes and have way more electric than they consume – could actually be a good industry to diversify into!

            And as an energy store its not just the volume that matters, its lifespan, price, reliability, EOL decommissioning/recycling costs, along with factors defining how you use it like how portable it is – can’t just move a pumped hydro station no matter how hard you might want to.

          2. The greater volume of the battery requires greater amounts of supporting materials. Four Tesla batteries fit in a shed, while this thing needs an entire shipping container worth of steel.

            The actual space it takes is irrelevant.

          3. And the volume of supporting materials and battery material is equally irrelevant as volume is – supporting and battery materials in this case are cheap, probably already recycled and so less polluting than the mining and refining required to make the Tesla battery. Then you have to take lifespan into account too.

      2. In crowded urban areas I’m sure volume to kWh is a very important metric. Elsewhere… space is cheap. Where I grew up half the homeowners could probably plop one of those “storage containers” down in their own back yard all for their own personal use and never miss the space!

        I’d be more interested in the money to kWh metric. Given the cheap, plentiful and not-so-harmful materials that go into these I suspect that if mass-produced they might be a contender. Especially if one considers the end-of-life cost, disposing of or recycling the contents or worse, cleanup if the thing ever breaks open.

  3. I can’t believe people are still pushing CO2 storage. The thermal losses from compressing a gas are not recoverable in any realistic use scenario. Furthermore there are much better gasses to use other than CO2.

    1. I’d be interested in the better working supercritical fluids to drive a turbine, can you name any ? Or point me to a paper.

      I’ll compare a supercritical water turbine to a supercritical Carbon dioxide turbine which may make it clear why there is so much interest in CO2.

      The critical temperature of Carbon dioxide (31.0 °C) is much closer to room temperature that the critical temperature of water (374°C). And the critical pressure for Carbon dioxide (73.8 bar) is less that 33% of the critical pressure required for water (221.1 bar).

      Because the pressure and temperature to create and maintain supercritical carbon dioxide is much lower than is needed for water as the working fluid, building a device using materials that are available today, means that the temperature and pressure differential between the high end and the low end can encompass a larger area within the thermodynamic cycle. And that larger area would correspond to more energy that can be extracted from the exact same source of thermal energy. Basically if your hot end is hotter or your cold end is colder, or both, then you can usually extract more energy.

      Carbon dioxide becomes super critical at a critical temperature of 304.13 K (31.0 °C; 87.8 °F) and a critical pressure (7.3773 MPa, 72.8 atm, 1,070 psi, 73.8 bar).

      Water becomes super critical at critical temperature of 647 K (374°C; 705 °F) and a critical pressure (22.11 MPa, 218.4 atm, 3210 psi, 221.1 bar ).

      The CO2 molecule (44.01 g/mol) has a higher mass than H2O molecule (18.01528 g/mol) so the turbine required to output the same mechanical power can be physically smaller. Smaller means easier to balance the shaft.

      The reason that supercritical fluids are used is because they have all the properties of a gas and the mass of a liquid. Basically the turbine blades are not rapidly etched away by the working fluid.

    2. And how much energy is actually lost to these thermal losses (I assume you’re referring to enthalpy pf vaporization/condensation)? Presumably it’s a sizable fraction of the energy, but with a great enough price swing between high demand low generation periods (e.g. late afternoon) and low demand high generation periods it’ll still be profitable. Plus, you can just send the gas through a heat exchanger with a water based heat reservoir between each stage of compression/decompression, and with a reasonably sized water tank underground (soil makes good insulation) it should hold the entire enthalpy of vaporization/condensation without too many degrees of change, and make use of the heat generated in condensation to help vaporize it when the time comes to draw power.

      Also, what superior gasses do you propose? You can’t just say “there are much better gasses to use other than CO2” and not even give any hints as to what those might be, because most people have no idea what that could be, myself included.

        1. Really? A higher adiabatic index will improve efficiency? But adiabatic index is literally how much it changes in temperature in response to compression. If you’re worried about thermal losses from losing the heat made during compression and needing to find some way to recuperate that during decompression, then the best choice is a gas with a very low adiabatic index so it doesn’t change temperature as much during compression/decompression. In that case a better gas would be a hydrocarbon like methane, ethane, or propane. With all those molecular degrees of freedom gained from having so many atoms, it’ll have a very low adiabatic index. Plus, the vapor pressure can be tuned by selection of the appropriate hydrocarbon or hydrocarbon mix. And if you’re worried about flammability, you can use partially or totally fluorinated versions of those hydrocarbons which will have the same adiabatic index and similar vapor pressure, as well as reduced or eliminated flammability. Unfortunately, they’ll have a very high global warming potential (GWP), but we’re basically dealing with refrigerants at this point so some low GWP and non-ozone depleting refrigerants could probably be reasonably used instead. But all this is slightly complicated, and refrigerants probably have issues I’m not aware of (e.g. cost, probable non-biodegradability, poorly studied long-term effects on the surrounding ecosystem if the stuff ever leaks), so we can just stick to CO2 for simplicity, the advantage of being a very cheap and common gas without any possible unexpected consequences of use, and enjoy the high but not too high vapor pressure. And we don’t want vapor pressure that’s too high because the whole point is to liquefy it. This makes all the gasses you mentioned unusable on account of the cryogenic conditions needed to reasonably liquefy them. If you’ll look at the Energy Dome diagram helpfully included in the article above, you’ll see that they’re storing their compressed CO2 in liquid form, and using more or less the exact strategy I mentioned in my last comment with the water tank to condense/vaporize the CO2.

          So, sure, if you don’t want to liquefy your working fluid (thus very low energy density) and have some way to manage the large temperature change of compression/decompression without killing your round trip efficiency, then go ahead and use those gasses you mentioned. But liquefying CO2 will work a hell of a lot better, even if only on account of the high energy density. Plus, since the heat change involved in condensation/vaporization occurs outside of the compressor/decompressor, you can force it to happen with minimal temperature change in a very easy and simple manner by making it condense/vaporize inside the water heat exchanger, thus removing most of the efficiency losses associated with the high heat of condensation/vaporization. And this is exactly what happen in that Energy Dome diagram. In other words, these people know what they’re doing and have a system that will work a lot better than compressed nitrogen or argon.

  4. Personally like the simplicity of isothermal compressed air energy storage solutions.

    Efficiency isn’t stellar. But it isn’t hard to beat hydrogen by a mile and retain the same “zero self discharge”.
    And unlike pumped water one can build it nearly anywhere. Compressed air also has the advantage of mainly needing a relatively cheap pressure tank. Unlike batteries that contain a lot more expensive resources in general.

    Downside with air is that it takes space. At least the tanks can be underground if geological conditions are suitable.

    However. Most people are critical of compressed air. Both due to the lackluster efficiency of shop compressors that aims at flow above any other spec. (and those not aiming at peak flow aims at low noise. Efficiency is often rather far down the list of priorities.) But also due to underestimating the amount of energy that can be stored.

    Now, compressed air isn’t the be all of energy storage solutions. Just that it is a decent solution at scale for handling the varying supply from wind power and other renewable sources. (Personally don’t see it making much economic sense bellow at least 400 MWh if one has a daily 20% depth of discharge on average.)

    Batteries makes more sense for day to day load/supply balancing.

    Biogas is better for seasonal needs. Mainly since it can complement the lack of solar power during winter. With the added benefit that the “inefficient” nature of it is rather useful during a cold winter if one puts the waste heat into district heating.

    Beyond this. Providing some standardized API for giving grid operators a better way to inform energy consumers about future availability can lead to more energy consuming devices scheduling their activity in a more intelligent/efficient fashion that is beneficial to reduce grid strain and resulting brown outs.

    But in the end.
    No singular solution alone is all that great by itself.
    It is a multifaceted problem requiring some diversity in the various solutions used to fix it.

    1. > if one puts the waste heat into district heating.

      District heating is typically done using slightly superheated water. Biogas production does not produce those temperatures. It’s low grade heat that would be best used to keep the bioreactor tanks from freezing over in the winter.

      1. Heating water above 100 C is still a fairly low temperature as far as a methane flame is concerned. Yes, methane doesn’t burn as hot as some other gases. But for boiling water it is plenty warm.

        Also seen a lot of district heating systems stay between 85-100 C, sometimes lower. Still plenty warm for most home heating requirements, even 65 C at the consumer is adequate in a lot of cases.

        And a biogas power plant can be much more local than most other thermal power plants. Making the need for long distance transport of the heated water less problematic.

        But even using the biogas for pure heating applications at the individual buildings is still using the collected biogas as stored energy. One generally don’t need as much heating outside of winter, making the production vs consumption ratio favorably skewed.

          1. Why would you turn the gas to electricity? You can heat your water, your home , and cook your food directly with gas? There’s even adsorption heat pumps available, so you can multiply the heat output.

            Hot water, space heating, cooking – that’s about 75% of the energy demands of a home. It’s rather the opposite way: you could use some simple thermo-electric device to get waste electricity out of the heat to run your lights and TV etc.

          2. Of course in hot climates you need AC, which can work on gas as well but it’s less efficient for the purpose.

            The gas network is also a magnificent battery, because there’s a huge volume of pipe laid down to carry pressurized gas. You can store months and months worth of energy into it, which is extremely difficult with any of the “alternative” methods like batteries or pumped hydro.

  5. So, no any affordable and DIY-capable solution for ~50kWh for individual, independent house reserve storage that could be used to store 12 hours of electricity for house, indefinitely until necessary, totally repairable, with no degradation, need for expensive maintenance, cycles limit and so on.

    Why is it always just yet another “solution” for yet another business or corporation you will be still dependent on?

    Individual energy independency, even when it is just a small reserve storage is some kind of taboo in modern society, or what?

    Whatever. Gas/LPG/Diesel generator is a way to go.

    1. You are right but slightly missing the point. We are talking about storage, not generation.

      If you have a battery, you can pair it with solar/wind power and store the energy for when the wind isn’t blowing and the sun isn’t shining. So power that would be wasted (generated but without use) will be stored for later (when it’s needed but not generated).

      1. I’m talking exactly about storage of energy for individual usage.

        Storing energy from highly unreliable sources like sun and wind is senseless for the more than half of the world. You need not just 12 hours, but more like 12 days of storage with not so high probability to “fill” it up. Not everybody lives in places with 365 sunny days a year or strong constant wind.

    2. Scale comes into the equation when dealing with domestic situations, if you can fit and afford a shipping container sized energy store go right ahead, nobody is stopping you. But can you?

      I have a tiny battery with a small solar array, tiny in capacity only – it is still a very heavy, large suitcase sized, and expensive object which limits how many of them you can practically fit in the domestic setting – they both eat potential living space and may need reinforced floors. Though thanks to the solar I reckon we could with a few tweaks to our lifestyle and a second battery easily go off-grid if wanted to – arguably a way more dependable solution than the ICE generator you probably haven’t turned over in years, and certainly won’t want to use much as its expensively made electric…

      Independence via energy storage even with petroleum products isn’t a small volume, idiot proof, or particularly cheap game. And arguably you are still not independent if you don’t also have the oil well and refinery in your back garden, all you are doing is delaying how long you can get go between requiring the outside infrastructure.

      1. I have 8 car batteries connected to 5kVA on-line UPS, but they are degrade within 3 years despite all precautions I added from electronic balancing to stable temperature and correct floating charge voltage. Lead-acid and Lithium batteries do not last long as reserve that used rarely and have to be fully charged all time. Thought about buying used Prius battery pack, but people who already tried that all say it does not worth it, unless you could get battery for free. NiMH also degrade in such mode. At least new car batteries are not very expensive (especially if you trade-in old ones) and easy to buy.

        And no, it is completely sesneless to build sun and wind crap living in the forest at location with 50 sunny days a year.

        So, ICE is still much reliable. With full LPG cylinder I’m shure I’ll have electricity for a day anytime – tomorrow, next week, next month and next year. Generator do not need much maintenance other than starting few times a year and checking oil level.

        During blackout it is much easier to find a fuel than to recharge suddenly emptied battery that suddenly lost half of its capacity during past half a year since the last problem with electricity.
        And I didn’t found any way to make some real-time battery capacity gauge that will show real capacity of fully charged battery stack just to be prepared that batteries degraded and you have much less reserve than expected.

        Electrochemical batteries are the worst thing ever in all that wonderful electricity and electronics world.

        1. You should be able to get a very long service time out of Lead Acid, if you treat them right, but Car battery really are not the right source.

          You would probably be surprised at just how much power you can get out of solar – even on a dark gloomy day some power is produced. It really doesn’t need to be a sunny day, the peaks you can get on a really sunny day are huge but you will get something practically all the time. But that is not to say it definitely makes sense where you are, as without some information to on the situation its impossible to give even a ballpark.

          1. > You should be able to get a very long service time out of Lead Acid, if you treat them right, but Car battery really are not the right source.

            Yes, but I can’t find any affordable source for reserve lead-acid batteries that is designed to stay fully charged for a long time with solid guarantees from manufacturer, that I will not occasionally find myself some year with batteries degraded in half. Best guaranty I got is 2-year warranty for exchange in case I could proove that I used battery strictly according to manufacturer specifications. Not much better than with car batteries, but significantly more expensive.

            > You would probably be surprised at just how much power you can get out of solar – even on a dark gloomy day some power is produced.

            Yes, but to get what I need I will have to buy more land to place all that solar panels. And somehow solve the problem with snow that like to cover solar panels a lot.

            To get “some” power, I could use TEGs on stove, f.e. it would be much cheaper, reliable and more readily available than solar.

          2. Depending on just where in the world you are a solar panel may not really catch and hold much snow – they should get pretty warm during the day so it won’t settle on them easily then and I expect they stay warm enough for it to slump off easily most of the time overnight as well. But of course just how cold and snowy/windy the area is would change that so dramatically. As a self cleaning method for if you are in an area that is cold/windy enough get the solar PV with built in water ‘cooling’ pipes behind then actively pump a little warm anti-freeze/water through it to clear the snow would work great I would think. With any significant angle on the panels you only need to make the lowest part of the snow touching the panel a watery lubrication layer to dump the whole pile.

            Sounds like you are not in a good location for solar though – and I did say only ‘arguably a way more dependable’, nothing works well everywhere. In the middle of a forest you would think bio derived renewables would be the self reliant choice. As there is no getting away from petrochemical dependency being the dependency on the outside world.

        2. If you live in a forest, you could run your IC generator on wood for free with a gasifier. You could use fallen limbs or practice coppicing. The waste heat would be useful in the winter.
          You could keep the battery bank to keep you going while performing maintenance on the genset or gasifier.

          1. I like this idea, but I also love Steam Engines too much to pass up the opportunity to suggest them as a good idea – gasifier works with efficiency losses, and the ICE is lossy too, so directly burning the dry coppiced timber in a well designed boiler and steam engine can be at least comparable if not better, with the same waste heat benefits too! And at least some of it in an easier to distribute way.

          2. People with wood gasifier powered IC engines get really good at disassembling and decarboning the engines.

            It’s a fun idea, because it’s coal rolley and ‘green’ at the same time, but no.

    3. I’m pretty sure the article was about storage within the grid, owned by the power company and not individual home backups.

      Gas generators require periodic running and maintenance. ICE engines kind of suck that way. They aren’t good for setting in a corner and forgetting until the emergency.

      Where I live power outages have been rare, ones lasting more than a couple minutes very rare, only a few in my ~40 years so far have been long enough to worry about refrigeration or anything like that and only one has lasted days.

      That one outage that did last days… everyone went to the gas stations but no one got any because the pumps were all electric!

      So if you want to prepare for that once in a lifetime power with an ICE generator you need to store a bunch of gasoline yourself. But gas goes bad so what.. cycle it through your car? And run the generator regularly. And all the other maintenance…


      My dream is a shed full of NiFe batteries and a roof full of solar panels. So.. I guess I’d still have to add water now and then. That beats the hell out of becoming your own gas station and also maintaining a gas generator!

      But I’m not there yet. So like a whole lot of other people I have a gas generator in the garage that “might” actually start if I need it and very little gas to run it with anyway.

  6. Does storage scale to meet global demand? I say no, but feel free to show my your numerical analysis. HAD should do an article on where fusion research is at right now, the entire industry and not just cumbersome projects like ITER etc., then tell me if we need storage at all for most locations? We can keep using carbon for another few decades and then roll out compact fusion reactors globally, everything else is a short term distraction, a waste of money, and a destabilization risk. I hope enjoy your northern hemisphere winter this year, because it may well be deadly for others.

    1. Even if we could already create usefully sized, net energy positive, fully functional pocket star driven electric generators the fact its so cutting edge means it is very very very very unlikely to be something you can quickly scale up and deploy. If the tech was ready for deployment right now, which to my knowledge it really isn’t you are still looking 10-20 years minimum before there are more than the odd prototype reactors out there. It takes time to build such facilities! Even longer to make them easier to mass produce, prove they are safe enough, reliable – in short that all the bugs are worked out.

      In the meantime you can’t keep making the situation worse, sticking your fingers in your ears to not hear about the disasters that man made environment abuse has already created, and which are only going to get more extreme. Not everything being tried now is likely to work out as the perfect longterm solution, but its better to use what we know how to do now as best we can to fix the problems of our making… So much better than fiddling while Babylon burns..

      Also STORAGE can never scale to meet a demand – its just STORAGE! All it can do is smooth out the supply and demand fluctuation – you still need something to generate power, perhaps some regulation on the demand side of things as well.

      1. There is no climate crisis that is linked to human actions, so we can wait for fusion to be commercialised. In fact we are better off boosting the global economy by freeing up energy reserves so that we can afford a rapid global scale deployment of fusion the moment it is ready to hit the market.

  7. I’ve been looking at solar powered hydronic heating, so dumping excess electricity from my solar panels into a 1000L steel water tank using a bunch of 24V heating elements, and heating water to 80-90C. To insulate the tank I was going to wrap it in R6.0 rockwool insulation, inside a small timber/plywood lean-to shed next to the house, my heat transfer calculations using excel came out to about 1.9kWh of thermal losses over a 24 period averaging 0C.

    Assuming a working temperature drop for heating of 50C (90C down to 40C) that’s about 66kWh of thermal energy that can be stored. I can get under my house to run heat pipes to some radiators, so I think this might be a fair bit more cost effective than buying 22kWh worth of batteries to run heat pumps assuming they are 300% efficient.

      1. Cool thing about resistive electrical loads is they’re about 100% efficient in turning electrical energy into thermal energy, especially when the medium they’re in is also absorbing any radiated energy. (Maybe I’m missing something here?)

        1. And a cheap heat pump can do 3x that, even on sub freezing days. More expensive ones are significantly more efficient. So you can net a whole lot more heat from your excess solar by using a heat pump.

          1. There is a relationship between the target temp, power required and outside temp with a heat pump – CAN do is the operative word – as under the right conditions they can do impressive numbers. In less than ideal conditions they are not doing the 5 times more heat provided than resistive heating…

            They are also rather more complex and can only get so hot, limited by how they are built. Where a resistance wire is very very cheap, practically impossible to kill if you don’t run it too hard, and can function up to stupidly high melt other metal temperatures – so if his chamber could take the pressure it could super heat the water even!

            Got nothing against heatpumps, but as a method to store otherwise waste energy for later they are stupidly expensive…

          2. Foldi-One: Certainly more complicated, but doubtful more expensive when you factor solar into the equation. Even at stupidly cold -3F (19C), my builder grade air source heat pump cranks out 1.74 units of heat for every unit of electricity consumed. When you’re talking about daily heating 1000L of water using excess solar energy, that extra 74% goes a long way! It only gets more efficient as days get warmer (though solar gets less efficient). Meaning you’d need a much smaller solar system to achieve the same amount of energy storage. Having built a completely DIY solar system this year, overbuilding is pretty pricey, especially if you’re paying retail prices for panels, inverters, racking, etc.

            For OP’s numbers of needing 68kWhr EXCESS (66 stored plus 1.9 lost)…that’s a LOT of power; 34 400W panels on a 5hr sun day dedicated just to making that resistive heat. If you can get even a lowly 74% boost on your output energy, you now only need 20 excess producing panels to do the same job.

          3. Sounds like they already have a solar installation, that is producing in excess. So that calculation has already been nullified, it is therefor now about cost to set up this hotwater store. And if you want to store energy as heat its far easier to get energy back out if the heat store is VERY hot, and very hard to beat a heating element for cheapness or reliability…

      2. Two reasons, the first is resistive heating elements are really simple to install into the tank, integrate into the electrical setup, and you can buy 1500W elements designed to run off 24V for $35 on eBay. The second is the Coefficient of Performance of heat pumps diminishes the greater temperature difference between the evaporator and the condenser. I want to heat my thermal store up to 70-90C, so I think an air to water heat pump is going to far more expensive than the resistive elements.

        1. I already have one in my tank which isn’t used, a mains powered immersion heater. It’s “just” a matter of dumping excess solar-generated electricity off it.

          I would send it up to the grid and be a good neighbour, but my meter doesn’t run backwards, so the economics dictate that I must use it in my household.

    1. Resistive heaters vs induction heated recirculating exhanger and an insulated storage tank
      Running water loops in the house is great, But you might want to consider a thermal transfer fluid with a greater storage capacity for the energy overflow storage. A few insulated drums of hot oily stuff will keep your waterloops regulated more efficiently.

  8. A battery is anything with stored energy. We’ve a dam near by that’s used by the power grid for storing energy. When the grid usage level is low water is pumped from one lake to another. When the usage level is high the valves are opened and it turns turbines. There are losses alright so its not very efficient, but as an electrical energy storage option its still fairly inefficient for something that was built 80 years or so ago.

  9. Thanks for the article, I just discovered iron flow batteries!

    I wonder if the pump mechanism would be suited for a manual activation (powered by human or animal muscles)? If yes that would make a nifty addition to the lowtech toolkit!

    1. Going to be a much more variable thing than X and only X parts make up the best options for any location. Nuclear is good, but do you want to site on near a fault line, in hurricane/tornado/typhoon locations, heck do you even have enough demand to make building a nuke here worth it.

      So storage is ‘the answer’ just as much as nuclear power or any other single tech can be called so. It is perfectly possible to run even a highly industrial nation without storage entirely from solar/wind if you really want to build enough of them over the large enough area, its just expensive, adding storage then changes the whole dynamic and your oversupply requirement drops hugely. And even with a Nuclear backbone to your infrastructure you will want battery/pumped hydro type systems as they are so very cheap and quick to ramp up and down for grid stability.

  10. Isn’t the worst that can happen with a diesel generator that enough carbon dioxide and other greenhouse gases are released to affect the planet leading to anthropogenic climate change and causing the extinction of all life as we know it?

  11. Back EMF, phase mismatch, transient spikes, and losses due to spin up are the usual reasons. However, the use of energy storage would make these a nonissue; leading to the pursuit of storage tech in the first place.

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