Using Hydrogen as a Battery

3 years ago by George Bower 79

2 Mw P2G Demo Plant in Falkenhagen, Germany

2 Mw P2G Demo Plant in Falkenhagen, Germany

In 2 previous articles we showed that EVs can be a useful tool in reducing CO2 in our atmosphere. In the second article we saw that, in addition to getting people into EVs, we also need to clean up the grid approximately 60% from where we are now. This implies adding more CO2 free sources of electricity into the grid mix.

Renewables provide that source but at very high penetration rates renewables would benefit from having a way to store the energy to smooth out the intermittent nature of wind and solar.

Could Hydrogen be used as a very large battery? Is anyone doing it? How much does it cost?

Germany has Ambitious Plans for Renewables

Germany has plans to increase their percentage of renewables from a current mix of approximately 25% to 45% by 2025 and 60% by 2035.

With an increasing percentage of renewables in the grid mix, the intermittency problem associated with wind and solar becomes more difficult to manage. Some way of storing energy from peak periods where there is a surplus would be very advantageous. Hydrogen could provide that storage medium. The official term for hydrogen storage is P2G, power to gas.

Why not batteries?

Batteries can be useful in smaller decentralized applications where the frequency between charging and discharging is short ie on a daily basis. With further cost reduction from Tesla’s giga factort we will see Li batteries being used more frequently to smooth out the daily fluctuations in solar. Day to day fluctuations require smaller battery sizes than seasonal fluctuations where very large storage requirements make a battery system too expensive.

Hydrogen storage could be used in these situations where the charge/discharge frequency is higher than a 1 day, sun up, sun down scenario.

Is anyone actually building a P2G Plant?

Germany already has multiple demonstrator plants up and running. One of the larger ones is in Falkenhagen, Germany and it is 2 MW capacity. Germany plans to have 1000 Mw of P2G plants running by 2022.

Intended P2G Plants In Germany

Intended P2G Plants In Germany

P2G Demo Plants In Germany

P2G Demo Plants In Germany

How does this Plant Work? What about the high cost of the Hydrogen infrastructure?

P2G Schematic

P2G Schematic

The plant uses electrolysis to produce the hydrogen. The electrolyzer is an alkaline fuel cell manufactured by Hydrogenics. Their plan is to move to PEM elecrolyzers which offer a more compact design as shown on figure 5.

PEM Electrolyzer Has Advantages Over Alkalilne

PEM Electrolyzer Has Advantages Over Alkalilne

The plants main purpose is convert EXCESS electricity from a wind farm into hydrogen. During period of very high wind activity the cost of electricity is essentially zero since without storage the wind generators would need to be shut down. Using excess electricity makes energy conversion efficiency a less important variable.

The infrastructure cost issue is addressed by injecting the hydrogen into the existing natural gas system of lines and storage tanks. Concentrations as high as 20% (page 7 ref 1) can be used with little or no change to the existing natural gas distribution system or to the combustion characteristics of natural gas. Using existing natural gas infrastructure mitigates cost. The 2 MW plant in Falkengagen has successfully demonstrated the entire process, including hydrogen injection into the natural gas system.

Is P2G Cost Effective?

Studies have shown that it is. The study (ref 1) showed that payoff period as low as 3.5 years (ref 1 p17) can be achieved under the proper conditions: where the cost of electricity is low and the cost of natural gas is high. This is exactly the situation in Germany.

A tornado chart which shows the effect of the primary variables is shown in figure 6. Cost of electricity and cost of natural gas have the highest effect on payoff time. A complete list of all the variables is shown in figure 7

Payoff Time For P2G

Payoff Time For P2G

List of Variables Used In Sensitivity Analysis

List of Variables Used In Sensitivity Analysis

Could P2G be in our Future?

I would say that under the correct conditions the answer is definitely YES. If P2G can be used as an effective tool in making renewables work then why not use it? Why not add this tool to our war chest of tools in our fight against Global Warming?

Interested?

Here is a link to Hydrogenics product catalog. All the specs for one module worth of equipment at the Falkenhagen P2G plant are in the catalog found here.

 

References:

  1. Integration of Wind Energy, Hydrogen and Natural Gas Pipeline Systems to Meet Community and Transportation Energy Needs: A Parametric Study
  2. Germany’s “Energiewende” driving power-to-gas From an Idea to market launch
  3. dnv kema Systems Analysis Power to Gas
  4. Hydrogenics Power to Gas IEA Hydrogen Technology Roadmap North American Workshop, Bethesda, Maryland- January 29, 2014

 

79 responses to "Using Hydrogen as a Battery"

  1. DaveMart says:

    The plan is to recover the process heat, which can push the efficiency of hydrogen production plus heat up to comfortably over 80%.

    If you are intent on using lots of renewables in the grid, then this is the reality of making it work, although it is pricey.

    Of course, since you are turning power into hydrogen, why not use some of it to power fuel cell vehicles and turn it into electricity in the car?

    That is why Germany is keen on fuel cell cars.

    Personally in spite of many assuming that I am in favour of fuel cell cars, I would prefer to generate most power using nuclear with at suitable latitudes ie certainly not in Germany or the UK but almost everywhere in the US a very big solar input to cover peak summer load.

    If you don’t fancy nuclear then at least renewables at a very high penetration rate can probably be made to work this way, although the cost is another matter.

    1. GeorgeS says:

      ref 1 is quoting numbers for the P2G part (not including the wind farm of around 250$/kw………not that much (if I have calculated it correctly).

      Looks like all the money is tied up in the wind farm.

      Wikipedia is quoting around 12,000$/kw for the Gabbord wind farm offshore from the UK. (again, if I have calculated it correct).

      This compares with numbers nowadays of up to 8000$/kw for gen 3 nuclear plants.

      Also it looks like around 25% of the Gabbord wind farm cost was in the offshore connection.

      1. DaveMart says:

        I can’t remember if it was these fellows, but I contacted one of the companies which projected wind to hydrogen.

        What I did not like is that they projected very low costs of power, which is fine if you are only taking the surplus when there is too much wind for the grid to handle.

        What was not so fine is that their figures then assumed very high utilisation rates for the electrolisers, which would only make sense if you were using the wind from dedicated turbines all the time, not just in gales.

        Of course you can spread the load to some degree, using batteries for interim storage, but not enough to get the high utilisation rates they had projected, and the batteries both cost money and reduce efficiency.

        They did not reply.

        There are a lot of dodgy figures around in renewables, and some of the financial engineering puts anything in the technical field to shame.

        Just the same it seems clear enough to me that a host of different technologies are going to play some part in energy production and storage, and if a lot of renewables are required, then only hydrogen and CAES have the right scale.

        CAES if pretty polluting, and I don’t fancy it at all.

        1. GeorgeS says:

          The ref 1 study used a capacity factor of 30% for the wind farm. but you can’t assume free excess electricity AND an average capacity of the farm at the same time….but the numbers are presented with cost of electricity as a variable so one could figure it out….but a 4 yr payoff is probably pretty optimistic as you said.

    2. Mark H says:

      “That is why Germany is keen on fuel cell cars.”
      I am still looking for an ERFCEV solution. The FCEV already has the electric motor and the smallish battery. EREVs only need mid-sized batteries. Lots of the hydrogen infrastructure problems are relaxed with an EREV which fixes a glaring problem with FCEVs. 40 mile AER Volt owners often go months without use of petrol.

      Battery storage? yes ERFCEV? Sure
      FCEV? I was interested in the Honda Clarity years ago primarily because of the home production. I really was not limited by the potential up front cost. Now that I plug an EREV into a 110V outlet and have the needed solar array to offset my usage, I am only one step away from completing the triangle and that is battery storage. I really don’t want to do that unless the utility company forces my hand. I certainly can not predict the future, but am pretty sure a superior battery will show up ahead of an hydrogen infrastructure.

      Not against a hydrogen infrastructure unless it is supported by fracked gas. Fracking may be safe until it isn’t. Watching a contaminated well means little to me. One lost aquifer and all gains are lost. I am very much in favor of converting excess renewable energy as suggested in this report.

      1. DaveMart says:

        There are not many technical objections to a PHEV FCEV.
        Greater energy density for the battery pack would be nice, but we are told that that is coming anyway.

        They have followed the KISS principle, and
        just concentrated on building a FCEV for the first models.

        I agree that by making them plug ins, hydrogen infrastructure would be minimised.

        Interestingly they would also solve the problem of making away from home charging pay, as it would not be needed and hydrogen stations would simply follow the pattern of petrol stations for charging

        Hydrogen does not ‘go off’ as petrol does in a tank either, and so would not have to be periodically burnt off as you have to in a Volt.

        Gas fracking will unfortunately be with us for a long time, whether or not cars are run on hydrogen, and certainly if a lot of renewables are specified to cover intermittency.

        It can be used around twice as efficiently as at present in home fuel cells though.

        To me most of the problems seem to be due to inadequate or even non-existent regulation of the industry and disposal of its waste water than inherent though.

        1. Mint says:

          Plugin FCEV makes no economic sense, and never will.

          PHEV already takes away 70-95% of mileage away from the ICE. Making the rest run on fuel cells is a huge amount of effort and investment to take a minimal amount of mileage and make it green. The cost/benefit ratio is horrendous.

          The application mentioned in the article – H2 stationary storage – is a far more sensible application for fuel cells. The reason is the cost of reliable, stationary power is well over $500/kW. Get a fuel cell to maybe $300/kW, and you have a low maintenance backup system that nothing can match.

          But to be competitive with ICEs in the automotive sector, fuel cells have to get well below $100/kW.

          1. DaveMart says:

            If you are not interested in getting away from petrol, why bother with batteries either?

            For some reason battery only folk seem to become perfectly happy to stick with petrol when it is in a PHEV, even though of course it is not zero polluting at point of use, and even though fuel cells combine effortlessly with batteries unlike an ICE with no need for high temperature exhausts, no stinky exhausts and no extra noise or vibration when the fuel cell switches on.

            The DOE already puts the cost of producing fuel cells at a volume of 500,000 vehicles a year at well under $50kw.

            To be clear what that represents, it is the cost using pretty much the stacks we can do right now, with only normal production engineering and none of the breakthroughs needed for,say, lithium sulphur batteries.

            Excess heat from even a modest fuel cell stack also solves the problem off heating a battery powered car and keeping the battery at a good operating temperature.

            Those are some of the reasons why fuel cell range extenders are being trialled right now for delivery vehicles where even a 5-10kw stack can, over an eight hour delivery day, provide another 40-80kwh and transform the range.

            Fuel cell REs are also being trialled in buses for the same reason.

            What is so wrong with that, and why are you so keen on keeping petrol?

            1. JakeY says:

              People are fine with using gasoline (or biofuels) with PHEVs because a combination of BEV and PHEVs can handle 85-95% of driving on electric drive. Mint’s point is that it does not make sense to spend a massive amount of money to cover that last 5-15% of driving.

              My perspective is that it just combines two expensive technologies into one for an even more expensive car. And the FCV is actually not suitable for PHEV duty without having a fully established infrastructure (the “range extender” used must use readily available fuel or it does not serve the core function).

              Maybe at some point, fuel cells, hydrogen tanks and hydrogen infrastructure will be dirt cheap. But at that point, where will battery and charger infrastructure be? As batteries and chargers improve, the idea of a plug-in FCV (and FCVs in general) only makes less and less sense.

              1. Very well said. Can I buy it by the word?

              2. DaveMart says:

                Only American’s get hung up by the supposedly ‘massive’ costs of a bit of infrastructure.

                Elsewhere it is just another fuelling system, along with the existing universal diesel and very common natural gas infrastructure.

                It also saves the not inconsiderable costs of fast charging infrastructure away from home, ans the thorny issue of coming up with a way of paying for them, other than Tesla’s notion of loading it on to the cost of the car, which will be rather tricky as cheaper cars with tighter margins would be involved.

                The only way to ensure that most of your mileage is pollution free in a PHEV is to greatly oversize the battery pack compared to your normal average journey time, which would not be necessary with a FCEV PHEV so you are lugging around less excess battery weight and paying for less in the first place.

                The costs of charging a non-Tesla battery car per mile of additional range needed away from home as subsidies are reduced is looking very high, way higher than putting in some hydrogen.

                Why the advocacy of a dirty, smelly expensive and inconvenient ICE in a PHEV as better alternatives become available I can’t conceive.

                It seems to me advocacy of battery electric gone mad.

                I feel no need at all to be against battery electric cars because I am pro fuel cells.

                In a rational world it would seem best to me to combine their respective merits for optimum performance in various mixes dependent on the task to hand, and of course how the relative costs work out.

                1. Mint says:

                  You think an ICE is expensive and are advocating a fuel cell instead? LOL.

                  You’re living in a fantasy. If
                  A) H2 cost as little as gasoline,
                  B) a fuel cell stack cost as little as an ICE,
                  C) an H2 tank took as little volume as a gas tank,
                  *and*
                  D) it was cheap to build 10,000 H2 stations,
                  then yes, it would be a good option. But you’ll never see these come true.

                  The PHEV is already proving not to have a clear advantage in appeal over a pure EV, despite pure EVs have only half the range expected in 5 years, and despite PHEVs getting free refueling infrastructure. PHFCEV will fare even worse.

                  There is yet another reason PHFCEV won’t work: Nobody will build it. Manufacturers on the fuel cell train (esp Toyota) don’t want people getting used to plugging in.

                2. TomArt says:

                  Americans are concerned about infrastructure costs because the country is big and the population density – nationwide – is low. We are not compact like Europe.

                  We have sprawling suburbs and “exurbs”, and even entire towns that serve no real purpose other than being “bedroom communities” (with cheaper costs of living) for the employment centers of the nation. Commuting 30+ miles one-way to work is commonplace for millions of American households, and 40-mile one-way commutes are surprisingly not uncommon.

                  And, the distance between employment centers is rather large, also, particularly once you look inland, away from the east and west coasts.

                  Any sort of distribution network that cannot use existing liquid or gas pipelines (or existing power grid) is prohibitive to cover the length and breadth of this country.

                  This is particularly true since we, as a nation, can’t even agree to fund the maintenance and expansion of our existing infrastructures (bridge repair, railroad expansion, etc.).

                  If the generation was distributed, then it would be more manageable – instead of national hydrogen pipelines, just have regional pipelines. Since renewables are also a distributed source (particularly solar and wind), then the hydrogen generated from regional excess renewables could be distributed regionally.

            2. Mint says:

              You just don’t get it.

              Put the same amount of money into PHEV and PHFCEV, and the former saves far more gas. Probably 2-3x as much.

              Put the same money CA is spending on 100 H2 stations towards EV infrastructure, and you have 1300 superchargers.

              The DOE cost estimate is ridiculous. It claims that even at a mere 10,000 units per year, cost is only $84/kW. If that was true, we’d see fuel cells all over the power industry. Ballard power is selling 2kW backup systems for $20k.

    3. GuyMan says:

      I thought Germany was a big supporter/leader in Desertec – Basically, CSP and using some molten salt for storage (where it’s much easier to store heat – think insulation, than electricity) – Perhaps the politics on North Africa are much bigger than the technical issues…

      http://en.wikipedia.org/wiki/Desertec

      And the obligation Wikipedia references which reference heat storage for up to a week –

      http://en.wikipedia.org/wiki/Thermal_energy_storage#Molten_salt_technology

      http://www.renewableenergyworld.com/rea/news/article/2014/06/research-continues-on-solar-with-molten-salt-storage

      This obviously isn’t PV, which is great on a rooftop, distributed, and cheaper – and wind is cheaper – but for “centralized baseload” which needs capability overnight, I thought Spain had pretty much settled that CSP and thermal storage was the way to go..

      1. DaveMart says:

        Here is solar thermal in Spain:

        ‘The developers say Andasol’s electricity will cost €0.271 per kilowatt-hour (kW·h) to produce.[8] Under current government policy in Spain, solar-thermal electricity will receive a feed-in tariff of just under €0.27/kW·h for the next 25 years.[5]

        Like every power plant with a thermal engine, cooling is needed for the working fluid. As Andasol is built in the warm middle of the south of Spain, every Andasol unit vaporizes 870.000 m³ water per year (according to the developer), or 5 l/kWh (1.3 USgal/kWh). Most power plants vaporize less water (typically less than 2.5 l/kWh), or close to none if they are cooled by river or sea water.[9][10] Although water supply is generally a problem in Spain, Andasol has ample supply due to its location near Sierra Nevada.’

        http://en.wikipedia.org/wiki/Andasol_Solar_Power_Station

        So it costs around $0.35kwh, and uses twice as much water as other power sources, which is a bit of a problem since unlike this plant most suitable locations are in very water stressed areas.

        pv is way better, and that still has a tough time without mandates, grid connection and supply at favourable rates when it is not available and so on.

  2. gsned57 says:

    Great Article Goerge, but I think it could play out another way and be cheaper. If EV’s can grow in penetration along side renewables we should use the EV battery capacity as the grids storage system. Utilities could set up systems to use X% of an EV battery as grid buffer allowing a two way street in the 85% – 95% band of your battery. This would be similar to how my utility gives me $20 a month for the ability to shut off my A/C for 20 minute stretches during peak use in the summer.

    Beyond using EV batteries for grid storage excess capacity could be used for things like water desalinization which is very energy intensive. During times of excess generation we crank up energy intensive activities to suck it up and with things like desalinization you can store the fresh water when it’s made and deploy as needed.

    1. DaveMart says:

      As the article says, the big problem is seasonal storage, not diurnal.

      Too big for batteries.

      1. Phr3d says:

        True, but in a perfect world -of plate chargers wherever you park, a 50kW battery, a 200mi H2 tank and H2 filling at any truck stop- a pretty nice synergy could be realized in the two-way street of power companies supplying and drawing from a million, then millions of EVs.

  3. Ocean Railroader says:

    I think pumped hydro would be cheaper then this and safer too. It could also be used on a power grid scale too.

    1. DaveMart says:

      ‘The main problem with gravitational storage is that it is incredibly weak compared to chemical, compressed air, or flywheel techniques (see the post on home energy storage options). For example, to get the amount of energy stored in a single AA battery, we would have to lift 100 kg (220 lb) 10 m (33 ft) to match it. To match the energy contained in a gallon of gasoline, we would have to lift 13 tons of water (3500 gallons) one kilometer high (3,280 feet). It is clear that the energy density of gravitational storage is severely disadvantaged.’

      http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-storage/

      There follows extensive calculations of how high you would have to lift, for instance, all the water in the great lakes to provide cover for even a few days worth of US power.

      Too many people.
      Not enough space.
      Not enough mountains.

    2. Doug B says:

      Possibly but only if the appropriate geography is available, the permitting/environmental issues are much greater for hydro.

    3. Nick says:

      It looks like we’ll hit fundamental limits on pumped storage.

      http://physics.ucsd.edu/do-the-math/2011/11/pump-up-the-storage/

      1. scott franco says:

        The article starts by assuming that we need to store all of the power produced in the USA for 7 days. It does not even consider that some of that power is ALREADY hydropower, meaning that it double counts hydropower, but never mind.

        There is NO storage problem with power at the moment. The NG peaker plants are more than capable of filling gaps in renewable generation. In addition, most of the renewables are fairly complementary, wind/vs. solar, which the article does not consider either (and it says so – imagining 7 days of no solar and no wind). The issue at hand is we consider dumping renewable power into heatsinks as a “waste”. Apparently having the sun heat your car to oven levels is not a waste, but dumping energy from solar panels IS, but again I digress.

        All that PSH has to do is store power necessary to offset power variability from renewables AS DEPLOYED BY THE POWER COMPANIES. This is an important point. There is a hell of a lot of solar capacity going on to peoples roofs, far more than any power company project, wind or solar. Most of that capacity is not stored, but that will change rapidly as people get tired of selling their power cheaply to the power company in the day, and buying it back at a higher price during the night (yes, the government is forcing the power companies to enter “neutral” agreements, but this won’t last — the government can decree gravity is null and void, but that won’t be viable either).

        The future of renewables storage is batteries to store some or all of the output of rooftop panels. Thats not because it is cheap, on the contrary, storing the power generated by your panels is an expense that equals the entire cost of the panels themselves. Instead, it allows solar users to get out of power trade agreements with the power companies. It is not economic voodo — the power company has lots of fixed costs, generation, distribution, and these all go away with the new solar model. And there is an unfortunate tradition with shrinking technologies/companies to try to charge their remaining customers more to make up for the ones that leave, which nicely accelerates the trend.

        Now, to complete the circle, the naysayers carp that there is no way solar can provide power for everyone, and they are right. Not everyone lives in an area where solar can supply all needs. In addition, there are a lot of industrial concerns that cannot generate their power through solar. An aluminum smelting plant comes to mind.

        So the requirement for PSU is not anywhere near the total power generated in the USA for 7 days. A good example is California. It needs to store far more of its water to meet its needs than it does, most of our water still flows to the ocean. Just applying PSU to the storage needed anyways would more than cover the renewables storage needed (in a state where virtually all areas can generate their own solar power).

        1. DaveMart says:

          About Tom Murphy, the author of the link I provided:

          ‘Tom Murphy is an associate professor of physics at the University of California, San Diego. An amateur astronomer in high school, physics major at Georgia Tech, and PhD student in physics at Caltech, Murphy has spent decades reveling in the study of astrophysics. He currently leads a project to test General Relativity by bouncing laser pulses off of the reflectors left on the Moon by the Apollo astronauts, achieving one-millimeter range precision. Murphy’s keen interest in energy topics began with his teaching a course on energy and the environment for non-science majors at UCSD. Motivated by the unprecedented challenges we face, he has applied his instrumentation skills to exploring alternative energy and associated measurement schemes. Following his natural instincts to educate, Murphy is eager to get people thinking about the quantitatively convincing case that our pursuit of an ever-bigger scale of life faces gigantic challenges and carries significant risks.’

          http://physics.ucsd.edu/do-the-math/tom-murphy-profile/

          I think he is relatively unlikely to have double counted and so on, although of course he is not infallible.

          Certainly he is unlikely to have made a 1,000 fold error in assessing storage, as you just did in a previous post, being somewhat confused about terawatts and gigawatts.

          He also happens to be very keen on renewables, and you can read elsewhere on his blog about the solar and lead acid battery system he installed in his house many years ago.

          It therefore seems pretty unlikely that he is either too innumerate to calculate the magnitudes he shows properly, or too prejudiced against renewables to do so fairly.

          1. Scott Franco says:

            “that guy is really smart”, is not an argument. Plus you clearly didn’t read what I wrote. Bye.

  4. Scott Franco says:

    Germany has about 1 terawatt of PSH:

    http://en.wikipedia.org/wiki/List_of_pumped-storage_hydroelectric_power_stations

    By that same list, the USA is roughly 12 terawatts, with California leading the pack of states.

    PSH is the rodney dangerfield of power storage technology:

    1. What is the most efficient power storage technology?

    2. What is the cheapest?

    3. What is the most widely deployed?

    All, of course, true of PSH. It is also:

    1. Deployable anywhere. Since PSH is closed cycle, it is fairly cheap to transport the working element to the location (small pipe).

    2. Existing downstream only projects (existing hydro dams) can be easily converted to PSH. Two dams that feed each other in levels is ideal.

    3. PSH adds to total water storage available, crucial in states like California with water issues.

    1. Mikael says:

      Gigawatt, not Terawatt.

      1. scott franco says:

        Ooops, sorry.

    2. Ocean Railroader says:

      Virginia has the world’s largest pumped hydro power plant in Bath County Virginia http://en.wikipedia.org/wiki/Bath_County_Pumped_Storage_Station

      There was a idea I was thinking about that in theory Virginia Power could shut down all of their coal fired power plants and replace them with solar power and wind energy.

      The first phase of this idea would involve building several 200 mega watt solar panel farms across the state. Or you could have tens of thousands of home solar power systems feeding power back into the grid. I would devote one of the pumps at the Bath County hydro project to pulling in all of this excess solar power and pumping it into the storage lake for the night time to generate it.

      If this idea was upgraded on a massive scale Virginia would be in luck in that we have a lot of large creeks and rivers in the Blue Ridge Mountains we can dam to build dozens of large scale pumped hydro projects. Along the way we could build several massive hundred mega watt solar farms in the rural parts of Virginia. As if now I think Virginia Power is still run like it’s the 1950’s and wouldn’t be bold enough to try something like this.

  5. Jouni Valkonen says:

    I guess that if we have hydrogen and excess electricity, then we can synthetize from hydrogen methane and if we have methane and still excess electricity why not synthetize kerosene for aircrafts?

    Synthetic kerosene is somewhat more expensive than fossil oil based kerosene, but it has advantage that it burns more cleanly and therefore it reduces the need of maintenance of Jet engine.

  6. “Could Hydrogen be used as a very large battery?”

    Yes it is possible to demonstrate a working hidrógeno bases battery cell(s). But, the economic cost of operating a fuel cell need to be weighed vs. other battery storage technologies. Fuel Cells will always need fuel (an operation cost) where other battery technologies are closed systems with minimal operational expenses. Today pumped hydro fills this role on some grids. (watter operates in a closed loop pumped uphill to a dam)

    As far as using solar and wind on grid scale; there is no need for battery storage until renewables approach that cuts into the minimum night-time grid load. With current weather forecats it is possible to predict rewables energy production 24-48 hours in advance. Today’s grid can handle a neuclear, or coal plant shutting down for emergency maintenance with little notice. A change in weather will be less abrupt and have hours of lead time to plan for a balanced grid.

    To summerize; the question should not be “if grid storage is needed”, but when will it be a cheaper alternative to adding more renewable energy sources (wind and solar) to the grid? A hydrogen-based energy storage system needs to be competitive on a per kWh basis to rewables including cost of fuel over a life cycle of 15-25 years. Is this possible?

  7. protomech says:

    Hydrogenics claims 5.2 kWh/Nm3 for their hydrogen generators, all in. LHV of hydrogen is 3.0 kWh/Nm3, so this is actually quite good efficiency.

    http://www.hydrogenics.com/hydrogen-products-solutions/industrial-hydrogen-generators-by-electrolysis/outdoor-installation/hystat-trade-60

    Hydrogenics also supplies stationary fuel cells that claim 55% efficiency per Nm3 LHV of hydrogen.

    http://www.hydrogenics.com/hydrogen-products-solutions/fuel-cell-power-systems/stationary-stand-by-power/telecom-data-centre-backup-power

    5.2 kWh electricity input produces 1 Nm3 of Hydrogen, which can be fed back into their fuel cells to produce 1.65 kWh of electricity .. about 32% roundtrip efficiency, ignoring any other losses.

    It’s better than nothing if the alternative is throwing the energy away, and if you can recover some waste heat then maybe the efficiency will be a little higher. But it’s still not “good”.

    If storage is cheap then batteries are far more efficient. If production is cheap but storage is expensive, then maybe hydrogen storage is better.

    1. DaveMart says:

      I think it can probably be made to work, whilst lots of renewables without burning lots of lovely fossil fuels without using hydrogen can’t.

      The economics are going to be nuts, but that has not stopped the Germans installing lots of ridiculous at that latitude solar, so we will see.

      The problem is that something of the order of 50% of all the power wind generates comes in ~10% of the time, so that at the moment it is thrown away.

      You have to amortise the electrolisers though, and how are you going to do that if they only work a fraction of the time?

      The US though has way better resources than Germany, and not only in wind, but in solar.

      When questioned about what you do in the winter, solar enthusiasts like to claim that it will become so cheap that it would be simple to build way more, enough to cover that.

      I am a stick in the mud, and prefer to see true grid competitiveness first, but if you do overbuild there is no question that it is better to turn the surplus into hydrogen than throw it away.

      1. Priusmaniac says:

        @Davemart,

        While it is true that seasonal storage is more complicate because of the higher energies involved, I would not say it is impossible without either burning fossil fuels or without Hydrogen.
        There are other developments going on that give an hint at other possibilities.
        You mentioned CAES but you did not talk about the main potential of CAES that is underwater storage where volume can be much higher Seamus Garvey of Nottingham University is active on that with Eon by the way.
        There is also potential on electric storage in SMES, where actually the density is way higher than in any battery, fuel or whatever else. It just waits for cheaper superconductors then the ones we have now.
        But above all we can burn biomaterials stored in the summer for the winter, like wood and biogas. Of course the biogas needs to be stored as well but since gas use is going to disappear in the domestic area thanks to heat pumps, passive houses, solar heating and moreover the switch to induction cooking and combined solar boiler with heat pump warm water. Thanks to this the present existing fossil gas storage is going to become available for biogas storage so that the electric winter needs can be met. No need for fossil fuels or Hydrogen.
        The other smaller day/night and wind no wind variations can be handled by pump storage, batteries, flow cells or the other systems.

  8. pjwood says:

    George, I respect your efforts but have to drill for how I see it.

    RE: Cost Effective:
    “Studies have shown that it is. The study (ref 1) showed that payoff period as low as 3.5 years (ref 1 p17) can be achieved under the proper conditions: where the cost of electricity is low and the cost of natural gas is high. This is exactly the situation in Germany.”

    ??

    Places like Bloomberg/WSJ relate costs of about $.32/kwh, vs the EIA’s claimed $.12/kwh in the U.S. So, it is not the case that electricity is cheap in Germany, perhaps from our own perspective.

    Neither is natural gas. The chart claims a ‘Normal Value of $.12/cubic meter’. That equates to about $3.39/mmbtu, which is the more common metric. German mmbtu prices are nowhere near this low. Even amidst all our shale, the U.S. has gotten steadily back above $4 (and coal use is up). The big problems we’re having in the northeast stem from LNG tankers going to Europe, where they got about $8/mmbtu last year. The big Russia / China natural gas deal, this year, was penned at $9.93/mmbtu ($400bb, for 350-380k cubic meters).

    So back to the comment “This is exactly the situation in Germany”. Saying that without mathematic reconciliation? C’mon, George. Do you really think that is true? Maybe I missed something else you are relating it to?

    What we can say about Germany (and my Bavarian au pair agrees 😉 )is that gasoline is 3X as expensive as electricity. IOW, both are expensive, and the same EV/PHEV math works. Unfortunately, electrolysis at 3x the watts price, and 2x the natural gas price, would make their H2 storage rather pricey.

    I think molten salt is among the promising. Projects, such as the 280MW (not 2MW) Abengoa Solana, are already on the ground using simpler solar thermal storage. Most of the problem is in the marriage of the solar daytime peak, with a peak load that is generally within the following 4-6 hours.

    1. GeorgeS says:

      The tornado chart used a range of NG prices of 0-.325$/m3. I did the conversion and came out with 8.92$/million BTU. I think the spot price for NG in the US is around 6$ now so the numbers look realistic.

      I went and checked spot price for NG in Germany and I got 32 euros/mwh.

      32 euros/mwh converts to 12$/ million BTU so the spot price for NG in Germany seems to be higher than the highest value used in the parametric analysis on the Tornado chart.

      The words in ref 1 (Tornado chart) also state the same thing so this makes me believe that my conversion (PITA conversions and prone to errors I admit) are correct.

    2. GeorgeS says:

      pj

      The cost of electricity is zero if you are otherwise throwing it away.

      The point being: if you have a huge excess that you can’t deliver to market then the price is way low.

      1. pjwood says:

        I see your point, on wholesale 24hr price volatility, especially with the renewables penetration of Germany (~30+%). One thing to also consider is that, unlike land based windmills where production at night is a common occurrence, ocean based installs tend to produce more in step with daytime power loads. That would counter-argue for H2. Nuclear capacity perhaps makes a better argument for cheap watts, overnight.

        Sorry, didn’t mean to suggest you overstated NG prices, as you explained that as the condition in Germany. Between all the conversions (mmbtu, bcf, cu mtr) and the timing with which you take “spot” quotes, it is very easy to come away with different conclusions.

        Free watts and electrolysis (w/o NGas) are a great way to go, so long as the duration of over-production of power is enough to paydown the equipment. I got a little lost on whether we were using natural gas as a feedstock?

  9. Mikael says:

    “Germany has plans to increase their percentage of renewable much more than any other country.”

    *lol*… That is true if you only know like 5 countries in the world. 😉

    The real number is about 31% of electricity from renewables, not 25% for Germany. And changing 29 percentage points of electricity to renewables in 20 years is pretty unambitious.
    Most EU countries would have to reduce their pace today to get down to that pace. And that is in an industry where the pace is only increasing.

    Just to give one example. Denmark has the goal to go from around 43% today to 100% renewable electricity (and heat) in 2035.

    1. DaveMart says:

      The last I heard Germany was a touch more populous than Denmark, and the Norwegian hydro system couldn’t back up and make possible the very high percentage of renewables that it permits in Denmark, as there are not enough mountains and lochs by an order of magnitude.

      1. Mikael says:

        I agree with everything you wrote, but which doesn’t change anything I wrote nor changes the fact that the statement in the article is very much wrong.

        1. DaveMart says:

          And I agree with what you wrote! 😉

          1. Mikael says:

            Not I get the view point of your comment. But I needed to read it a few times more to get it. 😛

            People really underestimate the enormous amounts of energy that are generated every minute and every hour and how extreme the energy storage would have to be just to store it for an hour or two, or a day.
            Talking about two days or a week and it just get ridiculous.

            Still there are some who manages to think that you can produce electricity during the summer and get it back in the winter, 6 months later or so, as a valid concept. Like if the coal plants had a magic room with special coal made out of last summers sunshine or so.

            1. DaveMart says:

              Funnily enough hydrogen and salt cavern storage have the right scale to manage it, which is more than can be said for the supposed alternatives.
              It surprised me too, but seems to be the case:
              http://www.kbbnet.de/wp-content/uploads/2011/09/Present-trends-in-compressed-air-energy-and-hydrogen-storage-in-Germany1.pdf

              Cost is another matter entirely.
              Of course 50 or so nuclear plants would massively reduce the problem, as they would provide plenty of baseload for Germany, but they are apparently too worried about the possibility of tsunami in Bavaria! 😉

              1. Mikael says:

                It is definitely an interesting solution. As “little” as a space of 200m x 200m x 200m could store a TWh worth of electricity if stored at 3000 psi.

                Then we are talking numbers that actually can do some difference on a larger scale.

                And since Germany, Poland and Denmark (and to some extent the UK and the Netherlands) have the best grounds for salt caverns in Europe I assume we will see this as a part of the solution there.

                From the little I know about it and have read about it seems like it might be fairly economical too.

              2. Phr3d says:

                I favor nuclear as well, but my conclusion is that -unlike 3 mile and Chernobyl- the Japanese reactor(s) are/were ‘over-engineered’ in every sense and meticulously maintained.
                It is hard to argue with a conclusion that IF your very, very, very conservative engineering is Ever wrong.. well, cancel Christmas for a couple decades if that coast of Japan is any indication.
                I get the humor, but..

                1. DaveMart says:

                  That is a whole different discussion, which I don’t really want to get into here and divert from the subject being discussed.

                  Many of us in favour of nuclear power feel though that there was no disaster at Fukushima, and just a medium sized industrial accident, which led to no confirmed radiation deaths at all.

                  The confirmed killer, so far of around 1,000 people, has been from the unnecessary and hysterical mass evacuations, when the levels of radiation were far below that common in many areas of the world from natural causes.

                  The argument is presented here:
                  http://www.world-nuclear-news.org/E-What-was-deadly-at-Fukushima-2608141.html

                  It has also been debated extensively on ‘The Next Big Future’ blog.

                  As I said, I do not wish to debate the matter at length in the context of this article, but will simply add that I live within 15 miles of a nuclear reactor, and in the event of an accident would be going absolutely nowhere unless removed by force.

                  1. Phr3d says:

                    Thanks, DaveMart – it is a difficult subject to learn about, and other than natural/man-made numerical comparisons, not much knowledge for the public was imparted in this article. I will deduce that the 350mSv in Brazil does not apparently cause harm.
                    As a fan of nuclear, I obviously find myself in uhmm.. passionate conversations, and wish I had more understandable facts to convey in that situation.
                    but as always: you cannot reason a person Out of a position that they were not reasoned into.

                    1. DaveMart says:

                      I have dozens at least of links to much more full discussions and studies on the subject, but as noted and trying to avoid too in depth discussion here, so simply linked to something showing my own position rather than outlining in any depth the science behind it.

                    2. DaveMart says:

                      Link to one of umpteen discussions and assessments on the NBF website here:
                      http://nextbigfuture.com/2014/02/evacuation-deaths-in-japan-in-2011-were.html#more

                      You will find links to numerous other studies and discussions on the same site,

    2. GeorgeS says:

      @Michael

      Agreed. more than any other country is wrong. I’ve asked Jay to fix that.

      1. GeorgeS says:

        I meant Mikael, sorry.

        1. Mikael says:

          No worries. 🙂 I’m just fascinated that the myth that Germany is a green country somehow lives on while they are one of the most coal burning coutries in the world both in absolute numbers and as a percentage of electricity.
          And an ambition level which most of the time is to barely reach the EU regulations minimums and many of the times fighting and reducing the levels of the goals too.

        2. Mikael says:

          And I’m sorry for picking on a small error which doesn’t really change anything in your great article. 🙂

      2. DaveMart says:

        I did not realise that it was your article.
        The ‘GeorgeS’ as opposed to the ‘George Bower’ had me fooled! 🙂

        Many thanks.

        1. GeorgeS says:

          My name is George Stuart Bower.
          I had the unfortunate occurence that my parents decided to call me Stuart.

          If I had to do it all over I would have gone with George.

          Compound this with the fact that I play the Violin since childhood.

          So a kid named Stuart, that plays the Violin has a tough time in high school as you might imagine.

          Then I became an Engineer and now I am retired and a useless and old member of society sucking on Medicare and Social Security.

          However I have been told by my republican friends that that is OK since I paid into the system. (the fact that I will take 100$ of benefits for every $ I put in is OK I guess.)

          Sorry for the rant. I don’t get paid for this EV/writing business but Jay has promised me some InsideEV stock options so I just keep going. There’s gold at the end of the rainbow 🙂

          1. DaveMart says:

            Think yourself fortunate.
            Here in England we usually simply behead Stuarts! 😉

  10. DaveMart says:

    The reason I don’t dismiss power to hydrogen altogether is because of home fuel cells.

    They are expensive at the moment, and not fully reversible, but the technology is changing fast, driven by the Japanese giants.

    They are based on turning natural gas, or biogas for that matter, into hydrogen and using that to provide both electricity and hot water.

    Combined efficiency is way over 80%.

    Just that technology would around double the efficiency of natural gas burn in the US, where single turbine gas burners not combined cycle is usual, and where the heat is just thrown away.

    That would pretty much be enough to eliminate coal use.

    The really neat thing though is that if the fuel cells were reversible then solar, and excess wind when available, could be used and turned into hydrogen.

    So there is no issue of amortising electrolisers, as they would be available anyway.

    Excess hydrogen, enough to cover winter use, is storable in salt caverns through the natural gas pipework net at good round trip efficiency.

    Such a system could not approach the very low CO2 levels of a mainly nuclear system, but it could integrate solar, wind and gas in a very effective way.

    1. pjwood says:

      “Excess hydrogen, enough to cover winter use, is storable in salt caverns through the natural gas pipework net at good round trip efficiency.”

      That might be getting too optimistic. We don’t have the pipes to support the new locations of frack gas without winter demand spikes. Saline aquifers and salt caverns have their own geography, that makes it one step more challenging.

      A lot of the friction surrounding carbon capture would apply to H2 storage, with the pressures and locations we’d be asked to achieve. Each of which having its own power requirements, after you get the CO2, or H2. Southern Company had a 250mm DOE loan to make the 582MW Kemper, MS, plant a model of effective CCS. At commercial scale, the boondoggle got exposed. CO2 and H2 may amount to different discussions of volume at pressure, but like others are saying the requirements are vast. Is the price on logistics reasonable?

      1. DaveMart says:

        Have a look at the link I provided.
        I ain’t an engineer, so simply try to assess what is the consensus amongst those who are, and they seem to be happy.

        I did not spot any of the obvious ‘gotchas’ which I also normally check for, and happen remarkably often when folk get too enthusiastic in the technologies they support, even scientists and engineers.

        Getting the hydrogen to and fro from the caverns, at any rate in Germany where the study was focussed seems to be fine too, as existing natural gas pipelines are to be used, with the NG mixed in, as this rather formidable US study outlines:
        http://www.nrel.gov/docs/fy13osti/51995.pdf

        In any case salt cavern storage is not the only option, as the hydrogen can also be turned into any number of forms which are liquid at room temperature, including methanol and DME.

        All that is at an energy and financial cost, of course, but with hydrogen and its products you can most certainly store energy in enough quantity to cover seasonal variation in renewables.

        I don’t really fancy paying for it, and would rather simply build loads of nuclear and not have to bother, but if you ain’t gonna do that and want to have loads of renewables without fossil fuels in mega quantities, you certainly need hydrogen.

  11. Assaf says:

    Thanks George for a highly informative post.

    I think that just like the power-generation challenge itself, the power-storage challenge will require a combination of many different solutions.

    EV V2G is a good one; sounds like H2 might be a good one as well, assuming that long term it doesn’t involve reliance upon natural gas drilling.

    There are many others. My brother-in-law is in some startup developing a chemistry-based one (some sort of plastic/ceramic material that can store the energy by modifying its structure? He’s explained it twice to me already, I’m still not quite clear on it).

  12. Another storage method that is not been mentioned is flywheels.

    http://temporalpower.com/what-we-do/technology/flywheels/

    Also, pumped hydro is already being used. And compressed air.

    Hydrogen leaks – has this been taken into account? What about compression for storage? What about the service life of the fuel cell?

    1. DaveMart says:

      Flywheels occupy a similar space in the energy storage system as batteries ie Good for overnight storage, does not scale anything well enough for seasonal storage.

      Pumped storage is also too small, as discussed above.

      CAES is the right kind of scale, but the compression and heating mean the use of a lot of nasty chemicals, as bad as fracking.

      Little or no compression is required for hydrogen storage in salt caverns, and leakage is minimal.

      See the link I gave above.

      1. DaveMart says:

        ‘I have worked many years with compressed air systems and have grown to dislike them. They are nasty and maintenance intensive, especially large systems. To work properly the air must be dried before it is stored, which takes a lot of energy, and lubricant must be added to it before it is used. The extracted moisture stinks like s**t and is nasty. If lubricant isn’t added to it when the air is used valves and such seize up quickly, and of course it is difficult to contain the oily air and clean it after it is used. With pneumatics the devil is in the details.’

        (Robert KLR, comments)

        http://phys.org/news188048601.html#jCp

      2. Pumped hydro is as big as you make it. One cubic meter of water that drops 1 meter can generate ~1kWh. More water at a higher elevation equals more capacity.

        I think that flywheels last a good bit longer than over night. They are virtually frictionless with magnetic levitation and vacuum in the housing. The new installation in Ontario is 5MWh I think. It is scalable.

        Compressed air can be done in underground spent gas fields.

        Grid storage batteries that are made cheaply, because they do not have to be light and compact are another option.

        No takers on my questions about hydrogen? Leakage, storage compression, conversion losses, fuel cell longevity?

  13. Alonso Perez says:

    Hydrogen is actually viable for this kind of application, because it is cheap to add storage a lot of energy capacity (just gas tanks) at any given power level.

    Still the case for Hydrogen might not be too strong if liquid metal utility scale batteries prove to be practical (http://phys.org/news/2014-09-liquid-metal-battery-grid-level-storage.html). We will probably find out by the end of the decade.

    I definitely do not see a sensible path towards hydrogen being widely adopted for cars.

    1. DaveMart says:

      If you re-read the article you will see that although it is grid level storage, it is talking about covering peak load and ironing out fluctuations, not the enormous quantities of energy needed for seasonal storage, which is on a different scale entirely.

  14. jmac says:

    Every single means of electrical generation whether it is coal, natural gas, nuclear, wind, solar or whatever either requires switching and/or storage.

    Nuclear provides base line electricity.

    But, if we were to rely soley on nuclear we would have exactly the same problem that critics of wind and solar love to use as talking points.

    Imagine a world run entirely by nuclear reactors that run 24/7. At night, they are just as useless as solar since nuke plants run pretty much wide open and demand at night is relatively thin.

    Nuclear power plants by that standard are just as useless as solar that can’t deliver at night versus nuclear that must deliver at night no matter what.

    The bottom line is that we need a storage system to capture electrical production from various sources, including nuclear, fossil fuels and renewables.

    A hydroelectric dam just can’t stop the penstocks just because some guy turns off his lights at night and decides to go to bed.

    Storage is badly needed for ALL types of electrical generation, especially renewables but also for fossil fuels and nuclear generation.

    1. DaveMart says:

      For a flow of 1kw or so you only need around 10kwh of storage to cover the difference for day and night, which we can do with batteries for either nuclear or solar.

      The problem of winter and summer peak is not so bad for nuclear, as it is available at both times at the same rate.

      Solar clearly has no problem with the summer peak, and indeed can sensibly be used to top up nuclear then, but has an awful time in the winter when demand is high and solar power lowest.

      San Diego can scrape by perhaps, Chicago is a different matter.

      There would be a massive gap for months on end between demand and solar supply.

      Wind can help some, but the gap is still of a different order of magnitude to daily variation.

      It can be covered basically by either burning very large amounts of fossil fuels or overbuilding renewables.

      If you are overbuilding you might as well store what you can, and further narrow the gap.

      The problem is worse the further you go from the equator, which is why the Germans are so interested in hydrogen storage.

      Some combination of overbuild and store or burning fossil fuels is what the choice boils down to.

      1. DaveMart says:

        I knew I was forgetting something!
        Battery electric cars would do most of the daily balancing for a nuclear-heavy grid as they are charged at night.

        Unless people can be persuaded to charge during the day instead that would further imbalance a mainly solar grid.

        Storage to cover daily variation would pretty much simply be needed in small quantities to cover the breakfast and evening rush.

        Solar is no better off for that, as the it is too early and late usually for the sun to have much power.

        1. Phr3d says:

          again, though – when EV vehicles reach a minimum break-even (unknown number), a million(?) plugged in EV -could- supply that hour(s) load-balance, correct? Just quik-mathing, I know.. or better, any idea how many EV Would need to be charging/tied to grid to have a hope of providing this hour(s) load balance?
          Use small words, LOL.

          1. DaveMart says:

            I ran the figures for the UK, as I live there and am most familiar with it.

            It has lousy solar resources and putting solar panels there is perfectly mad, so the calculations are a lot simpler than for the US which in any case has many climatic zones over several latitudes which really need calculating separately.

            So the UK has a fleet of around 30 million light vehicles.

            At 10,000 miles/year and at the efficiency of the Leaf of around 4 miles/kwh you might need 2,500kwh/year

            At 8760 hours in a year that is more or less 0.25kw of flow.

            So around 7.5GWe of power is required.

            If you charged all the cars in the slackest 6 hours of the night then you would need a fleet of 30 1GWe reactors, which is neat as that is around the UK summer baseload.

            In winter peak load is around 60GWe, so even for nuclear there would be considerable seasonal variation to cover, but nearly 30GWe less than for solar, which at the latitude of the UK is as near to zero for some months as makes little practical difference just when top load occurs!

            For areas further south such as New York winter and summer load are much more even due to air conditioning in the hot summer, and so nuclear can do a better job of matching seasonal load.

            Daily variation is pretty well covered everywhere if you charge your car at night.

  15. jmac says:

    Electrical demand varies throughout the 24 hour day.

    There is uneven demand on the electrical grid.

    This is caused by human beings.

    Whatever grid you design must take this into account.

    Baseline nuclear, hydro and geothermal are at odds with mankind’s basic biorhythms, the need for sleep, etc.

    In other words baseline electricity is not the hero in this scenario but is perhaps the culprit.

    No matter what you do, you are going to end up switching. From nukes to windmills to solar to salt storage to h2 storage to gas fired to coal, ad nauseum.

    Switching electrical resources will most likely increase (not decrease) when an economical grid storage system for excess electric production is found.

    Grid managers will still have to distribute baseline electric generation mixed with renewables, but with the additional wild card of grid storage.

    Seems like there will be a whole lot of switching going on, no matter what form the grid might eventually take, and grid managers will be even more busy than they are now just trying to mix renewables with nukes, coal and gas, let alone grid storage resources.

    We do NOT need 24/7 baseline electricity.

    Humanity actually goes to sleep at night.

  16. JakeY says:

    There’s a couple of issues with this thing.

    1) Supposedly the natural gas grid solves the large scale storage issue. However, from the diagram, it appears they don’t separate the hydrogen back out when using it from the natural gas grid, but rather just uses the natural gas to generate electricity (I’m assuming a turbine plant). Given the extremely high costs of running a turbine plant in Germany (because it’s so rarely used) that might be a deal-killing issue.

    2) It’s all well and good that the electricity is “free” or “excess”, but the equipment used to make and store the hydrogen (and then generate electricity) isn’t. So the critical question is if the entire system can be amortized properly. They claim it is possible because of the high cost of natural gas, which goes to the last point.

    3) The way this system is used is not as a “battery” because it’s not primarily storing/generating electricity (unlike other storage solutions). Rather, it’s primarily being used to feed a natural gas grid. So it still does not solve the main intermittency problem with grids with high amount of renewables. To solve that, it has to primarily function as electricity storage. Otherwise, grid operators still have to build an overcapacity into the grid.

    So the comparison would be the cost of a grid that’s built with minimal overcapacity plus a large amount of storage, versus this solution where they build the overcapacity anyways, but use the overcapacity to make natural gas to pay for it.

  17. Patrick says:

    If you want renewable energy storage, there are many cheaper solutions: molten salt, “dirt” batteries, pump storage… V2G is even more viable. Even if the energy to make the H2 is nearly free, the fuel cells that convert H2 back to electricity are not cheap and don’t last long. Fuel cells need a few more decades in the lab.

    1. Priusmaniac says:

      @Patrick

      That is true for day/night or wind/no wind situations but there is indeed a more complicated situation when you need to store energy for seasonal variations. In the winter you have the same wind but much less solar power, while in the same time you have much more electrical demand for the heat pumps, so you need to find a way to compensate that.
      Davemart finds that Hydrogen generated in the summer and stored in salt caves to generate electricity in the winter can solve that. I think that we can burn biomaterials stored in the summer for the winter, like wood and biogas. Of course the biogas needs to be stored as well but since gas use is going to disappear in the domestic area thanks to heat pumps, passive houses, solar heating and moreover the switch to induction cooking and combined solar boiler with heat pump warm water. Thanks to this the present existing fossil gas storage is going to become available for biogas storage so that the electric winter needs can be met.
      Other people think that compressed air energy storage can be made undersea in very large volume like Seamus Garvey of Nottingham University to store summer wind power for winter compressed air use to make electricity.
      Others still have other ways to store energy but for seasonal shift the possibilities are indeed much more limited.