Clean Power hydrogen power to gas

Published on November 24th, 2015 | by Tina Casey

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Here Comes The Hydrogen: $125 Million For “Transformational” Energy Includes Power-To-Gas

November 24th, 2015 by  

Fans of hydrogen fuel cell electric vehicles in the US got a pleasant surprise yesterday, when the Department of Energy announced that a company called Dioxide Materials is getting a slice of the agency’s new $125 million round of funding for “transformational” energy projects. Among its areas of expertise, Dioxide Materials is developing a low cost system that uses renewable energy to produce hydrogen fuel from water.

hydrogen power to gas

$2 Million For Clean Hydrogen

The new round of $125 million in funding for 41 clean energy projects comes through the Energy Department’s ARPA-E division, known to CleanTechnica readers for its work in the exploding diaper market and many other cutting edge energy adventures.

We’re zeroing in on the $2 million award to Dioxide Materials for a couple of reasons, mainly because we’re very interested in the emerging  power-to-gas field (the gas being hydrogen gas), and partly because among all 41 awardees, the Energy Department highlighted only seven in its announcement, and Dioxide Materials is the one selected to lead off the agency’s press release.

The Energy Department announcement was specifically timed to support President Obama’s participation in the COP21 climate talks in Paris, so we’re thinking that by underscoring this new investment in power-to-gas, the Obama Administration is signaling its future commitment to the emerging hydrogen economy. While not a one-size-fits-all solution, power-to-gas is emerging as a key strategy for some nations, Switzerland being one example.

With that in mind, take a look at the introduction that Energy Secretary Ernest Moniz gave to Dioxide Materials and the other six highlighted projects:

The ARPA-E projects selected today highlight how American ingenuity can spur innovation and generate a wide range of technology options to address our nation’s most pressing energy issues. As we look beyond COP21, the energy technologies the Department of Energy invests in today will provide the solutions needed to combat climate change and develop a global low-carbon economy in the future.

Group Hug For Renewable Hydrogen

Dioxide Materials is getting $2 million in funding for its project, so group hug for US taxpayers:

Dioxide Materials, Inc. will develop an alkaline water electrolyzer for an improved power-to-gas system, which is used to store energy in the hydrogen chemical bond. High conductivity membranes that can function under alkaline conditions could lead to a 10x lower electrolyzer stack cost because they allow higher current densities and enable systems that do not require platinum catalysts.

So, what does that mean? For those of you new to the renewable hydrogen topic, the idea is to produce hydrogen gas by “splitting” water through electrolysis, a process that deploys electricity to touch off a chemical reaction.

The process is energy intensive, but with the advent of low cost wind and solar energy it doesn’t have to be carbon-intensive.

Waste-To-Fuel, Too

The project is a riff on another system developed by Dioxide Materials. The company is already marketing a renewable energy-enabled electrolysis system for capturing waste carbon dioxide from industrial facilities and converting it to carbon monoxide, which can then be used to produce carbon-based fuels.

The company has patents pending in the US and elsewhere for its proprietary “catalyst mixture.” According to the company, this unique catalyst reduces the cost of producing the carbon monoxide “building blocks” by a factor of three.

If all this is starting to ring a bell or two, back in 2011 CleanTechnica noticed that Dioxide Materials was working with the University of Urbana Champaign to develop a liquid catalyst, with the aim of cutting the cost of reducing carbon dioxide to carbon monoxide.

Transformational Energy Projects

If the renewable hydrogen plan works out, that would certainly count as transformational. The few fuel cell electric vehicles currently plying the US highways depend heavily on hydrogen sourced from fossil natural gas, so in terms of lifecycle emissions they’ve been compared unfavorably to their battery EV cousins.

Fueling up with renewable hydrogen would turn the tables, at least for the near future. Despite their well deserved points for cutting greenhouse gas emissions at the tailpipe, in the US many grid-charged battery EVs still depend at least partly on natural gas as well as coal.

As for the other projects in the new round of ARPA-E funding, we’ll be taking a closer look at some of those in the coming weeks.

Among the seven highlighted in the press release are an “energy crop” system for ocean algae, a self-deploying hydrokinetic turbine, and a 50 megawatt wind turbine (yes, 50) with 200-meter ultra lightweight blades designed for offshore use.

Speaking of EVs, the complete list of new energy projects is a little thin when it comes to funding for cutting edge EV technology, we’re guessing because US automakers are already heavily engaged in that subject.

Among the slim pickings are two projects that focus on solid-state batteries, the next big thing after lithium-ion batteries. Here’s one that gets a little over $3 million in funding:

“Researchers at Corning Incorporated will develop roll-to-roll manufacturing techniques to produce thin ceramic electrolytes for solid-state batteries. Solid-state batteries offer higher energy density than conventional lithium-ion batteries, and avoid the use of flammable electrolytes.”

Fuel cell EVs also get a pair of projects, including this one funded at $2.8 million:

Pajarito Powder, LLC and its team will develop a reversible hydrogen electrode that would enable cost-effective hydrogen production and reversible fuel cells. The key to this technology is the replacement of precious metal catalysts with low overpotential base metal catalysts to dramatically lower the costs of electrolyzers and fuel cells.

Paris, Here We Come…With Snowballs!

It’s worth repeating that the new funding announcement has been carefully timed to support a strong outcome at the COP21 climate talks in Paris, with an eye to highlighting innovative US companies that could play a leadership role in the global clean energy marketplace.

Meanwhile, we hear that a certain US Senator is coming to Paris in support of the US portable ice chest industry (we assume Senator Inhofe will pack up his snowballs in a made-in-the-USA model), so good luck with that.

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Image (screenshot): CO2 conversion via Dioxide Materials.


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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.



  • Ken

    This article contains very misleading information. There is no economically viable renewable hydrogen in any near future so that misleading statement should be removed or amended with the actual facts.

    It is a simple fact that fuel cell cars are more polluting than gasoline cars because they must get the vast majority of their energy from dirty fracked fossil fuel and that will not be changing in any ‘near future’.

    It is also a simple fact battery EVs are already significantly cleaner than gasoline cars and getting even cleaner as the grid gets cleaner.

    From the EPA: Battery EVs are significantly cleaner than gasoline cars no matter the carbon intensity of the grid.

    The misleading information about battery EVs should also be clarified with the actual facts.

    • JonathanMaddox

      The economic non-viability of renewable hydrogen is entirely down to competition from low-priced fossil fuels with very expensive (“dirty fracked”) externalities.

      People are mainly interested in renewable hydrogen as one component of an energy system dominated by renewable energy sources, largely intermittent electricity generators like solar PV and wind turbines. Such an energy system itself can’t come about without deliberately “tilting the playing field” away from fossil fuels in an attempt to compensate for or eliminate those costly externalities. But the playing field *has* been tilted with impressive results in the fields of generation, transmission and battery storage.

      Additional energy storage and energy-fungibility technologies, which can compete with battery storage at the larger end of the grid scale, are in advanced stages of development and/or pilot scale. Power-to-gas in particular is one of these; others are variations on traditional pumped hydro storage and novel high-density thermo-mechanical storage techniques like those from Lightsail (compressed air with water for thermal storage), Isentropic (reversible heat pump with hot and cold storage in solid medium) and Highview Power (cryogenic “liquid air” cold storage).

      Most serious interest in power-to-gas today is in Europe, in the context of grid-scale storage of large amounts of excess energy from untimely intermittent generation, for use displacing existing uses of natural gas (in thermal power generation, as fuel for ICE vehicles and in domestic heating and cooking), not particularly for fuel-cell vehicles which nobody but Toyota really expects to reach a mass market in competition with battery-electric vehicles. A subsequent methanation step (Sabatier reaction) after water electrolysis is optional but well-developed: the idea really is to replace fossil methane altogether with clean electric energy, not to greenwash the use of fossil methane.

  • Here’s another one to add to the list: hydrogen cracking.

    http://phys.org/news/2015-11-energy-fossil-fuel-carbon-dioxide.html

    This unit operation would replace steam reforming as the main method for producing hydrogen from natural gas.

    And the research by Argonne National Labs

    “Conversion of Natural Gas to Hydrogen and Carbon Black by Plasma and Application of Plasma Black”

    https://web.anl.gov/PCS/acsfuel/preprint%20archive/Files/49_1_Anaheim_03-04_0973.pdf

    And for you EV nuts, it looks like Plasma black from methane cracking may be a very good replacement from natural graphite in batteries. Like the batteries your lord god king Elon Musk is going to be making. Graphite mining is a horrible mess and most of the graphite mining is in conflict areas. This may kill two birds with one stone. However, you’ll have to share the spotlight with Tina’s hydrogen fuel cell vehicles.

    • Joseph Dubeau

      Because of the politics, I don’t think “hydrogen cracking” will be discussed here.

      • Ken

        There is no such thing as ‘hydrogen cracking’ but the process you were attempting to refer to is being discussed.

        • Joseph Dubeau

          You don’t know what you are talking about.
          Please go troll on another website.
          I don’t care what your opinion is and I don’t respect it.

          • Ken

            I stated facts not an opinion. It is a fact that there is no such thing as hydrogen cracking.

            Stating facts is not trolling. What you did is trolling.

            Got that, yet?

    • Bob_Wallace

      Gosh, Michael, I thought you were someone who was concerned about global warming and the environment. Now you’re pushing natural gas?

      • Natural gas is already pushed. Oil and gas doesn’t need me. Plasma black actually looks like an interesting thing. Graphite sourcing will be tricky:

        http://www.techmetalsresearch.com/2014/03/going-natural-the-solution-to-teslas-graphite-problem/

        It looks like plasma black or carbon black is the subject of improving Li ion batteries already:

        http://ipo.lbl.gov/lbnl3193/

        “Berkeley Lab researchers led by Robert Kostecki have developed a technology for extending the capacity and improving the electrochemical performance and safety of high energy lithium ion batteries through a Berkeley Lab developed treatment of the carbon black additive used to make composite cathodes. The resulting lithium ion cells last one-third longer and deliver more energy, at no significant increase in cost.”

        It looks like a thing.

        Green car congress seems to have linked the research on hydrogen cracking products (H2 and carbon black) as well:

        http://www.greencarcongress.com/2015/11/20151119-iass.html

        So Tina’s right, but this will benefit Tesla as well. From the Berkeley labs research:

        copy/pasted again:

        Battery packs using the technology are capable of storing more energy within the same space used by conventional lithium ion cells. The technology brings substantial improvements to cathodes in lithium ion cells, paving the way for batteries that can take an electric car 300 miles between charges or store renewable energy in power grids. It also enables a more lightweight and compact lithium ion battery for the next generation of cordless power tools or mobile electronic devices.

        In the Berkeley Lab approach, the treated carbon black reduces surface reactivity when used with a high voltage lithium ion cathode. The treatment process extends the electrochemical stability window of conventional electrolytes and enables the use of novel, high voltage cathode materials. By inhibiting electrolyte oxidation on composite high voltage cathodes, lithium ion batteries built with Berkeley Lab treated carbon black additives exhibit improved cyclability, longer life, and operate with lower risk of cell damage or dangerous thermal runaway conditions.

        • Bob_Wallace

          An EV’s batteries would need a handful of graphite.

          Acquiring that graphic cannot be used as an excuse for reforming massive amounts of natural gas into H2 for fuel cell vehicles.

          • The process isn’t reforming. Hydrogen cracking eliminates CO2 generation and the need for water steam reforming. There’s only two products: hydrogen and carbon black (or plasma black). Carbon black from H2 cracking has far superior physical/chemical properties (translates to electrical, too) than other carbon sources. So there hydrogen for fuel cells and a superior product for Lithium ion batteries. Like I said above, materials sourcing for batteries will be a limiting factor. Cheaper sourcing is what drives overall costs down. Of course, maybe Tesla can make its autos out of carbon fiber produced from pet coke – the present source material.

          • Ken

            First of all you have your terms incorrect. There is no such thing as ‘hydrogen cracking’. You are thinking of methane cracking to make hydrogen.

            This process is not green or sustainable in any way since it still requires natural gas as feedstock. Most natural gas comes from the environmentally devastating process of fracking. Fracking causes cancer and other serious health issues. It also releases huge amounts of uncaptured methane into the air.

            From the Washington Post: A survey of hydraulic fracturing sites in Pennsylvania revealed drilling operations releasing plumes of methane 100 to 1,000 times the rate the EPA expects from that stage of drilling, according to a study published Monday in the Proceedings of the National Academy of Sciences.

            All big oil is trying to do is turn an extremely dirty process into a very dirty process. This is a useless improvement and is only another desperate attempt to slow and confuse the adoption of truly green tech.

            Big oil is, once again, misleading people into thinking that fossil fuel can suddenly be magically clean and sustainable when it can not.

          • You’re right it is methane cracking, but like other gas processing and oil refining units of operation nomenclature gets muddled. Hydrogen is separated from methane by catalytic cracking rather than steam reforming. The product becomes the thing rather than the reactant. It’s lazy on my part to use the product from cracking. I didn’t bother to google the nomenclature like you did.

            The rest isn’t my point. The point is there’s another unit of operation on the horizon that will make hydrogen production cheaper. There’s a lot of natural gas (methane) being produced whether we like it or not. The availability of raw materials (cost) drives technology. Folks interested in clean technology should be aware of that.

          • Ken

            Fuel cell cars using natural gas is not a clean tech in any way. They are actually dirtier than gasoline cars.

            From Clean Technica: “95% of US Hydrogen production is from natural gas, most of the remainder from the gasification of coal and it will not change for the better.

            Hydrogen is locked by the force of economics to natural gas and natural gas is increasingly locked by the same force to the practice of (environmentally devastating) fracking.

            For the same energy (1 gal gas : 1 Kg H2) Total Hydrogen CO2e emissions are 28.8% more polluting than gasoline fuel.

            Hydrogen FCVs offer no net Green House Gas reductions versus any other low performance vehicle. Replacing an EV, PHEV, HEV (or even a small-engined diesel or gasoline vehicle) with a FCV will represent an environmental set-back.”

            From Endgadget: “Reformed methane hydrogen is as bad as gasoline. Ford recently said that FCVs “do not provide significant environmental benefits on a well-to-wheels basis” compared to gas engines. And they could actually be worse, because recent studies have shown that methane infrastructure leaks are worse than previously thought (100 to 1000 times more) and, as a greenhouse gas, methane is 86 times worse than CO2.”

            Fuel cell cars are economically locked into getting the majority of their energy from dirty, fracked fossil fuel (natural gas). Fracking causes global warming and also cancer.

            From the Pittsburg health Foundation Report (2015): “Since the early 2000s and compared to the rest of the state, the heavily-fracked counties have seen a rise in infant mortality (13.9 percent), perinatal mortality (23.6 percent), low-weight births (3.4 percent), premature births/gestation less than 32 weeks (12.4 percent) and cancer incidence in age 0-4 (35.1 percent).”

            From US News: “Toxic Chemicals, Carcinogens Skyrocket Near Fracking Sites
            The spikes almost certainly will lead to a cancer increase in surrounding areas.”

            From the New York Times: “Citing Health Risks, Cuomo Bans Fracking in New York State
            State health commissioner, Dr. Howard A. Zucker, said the examination had found “significant public health risks” associated with fracking.”

            There is no clean fossil fuel. It’s important for people interested in clean technology to be aware of that.

          • Settle down sparky. If cracked hydrogen doesn’t produce carbon dioxide in production and makes black carbon for batteries, your Google info isnt relavent. Natural gas for electricity gen is here for a while.

          • Joseph Dubeau

            He doesn’t care about facts or the truth.
            He simple want to do his anti-hydrogen campaigning.
            He has be disproved many times and kick off of GCR twice that I know of.

          • Ken

            You are making false statements – again.

            I have been disproved about nothing.

            I have stated facts and you have completely failed to prove any of those facts untrue – again.

            Where are your facts? I am still waiting.

          • Joseph Dubeau

            It’s the truth. You are being exposed.

          • Ken

            Wrong. All that happened is you have been exposed making false statements – again.

            All that has happened is that you have been exposed as having zero facts – again.

            Where are your facts? We’re all still waiting.

          • Ken

            Wrong. The source of the hydrogen is 100% relevant. That source is still dirty, fracked natural gas. I have proved that natural gas is not clean.

            The fact that something very dirty is used to generate electricity is irrelevant. The point is, it is not clean and needs to be replaced by true green sources.

            Got that, sparky?

          • Joseph Dubeau

            Did you see this report on BBC?

            “Unwanted food produces 21 million tonnes of greenhouse gas in the UK every year”

            “An experimental drone fitted with sensors is being deployed to monitor gases rising from rubbish dumps.
            The unmanned aircraft is being flown above Britain’s 200 landfill sites to study a major source of UK emissions.
            The latest estimate is that unwanted food produces 21 million tonnes of greenhouse gas in the UK every year.
            Although the number of landfill sites is being reduced, the emissions from decomposing matter are set to last for decades.”

            COP21: Drone to monitor rubbish dump gases
            http://www.bbc.com/news/science-environment-34938893

      • Joseph Dubeau

        No, we should save all the natural gas for EV charging at night.

        What’s wrong with cleaning up the the methane?

        “Instead of burning methane (CH4), its molecular components, hydrogen (H2) and carbon (C), can be separated in a
        process called ‘methane cracking’. This reaction occurs at high temperatures (750°C and above) and does not release any harmful emissions.

        While hydrogen is the main output of methane cracking, its by-product, solid black carbon, is also an increasingly important industrial commodity. It is already widely employed in the production of steel, carbon fibres and many carbon-based structural materials. The black carbon derived from the novel cracking process is of high quality and particularly pure powder. Its value as a marketable product therefore enhances the
        economic viability of methane cracking. Alternatively, black carbon can be stored away, using procedures that are much simpler,
        safer and cheaper than the storing of carbon dioxide.”

    • JonathanMaddox

      Graphite is mined mostly in China (of course), with the very distant runners up being India, Brazil, South Korea and Canada. While obviously graphite mining is a filthy process, as it’s a filthy substance, I’m not at all sure what you meant by “conflict areas”.

      • Conflict areas is a problem with natural resource extraction, i.e. blood diamonds. Graphite deposits and the production of graphite is mostly done, as you say in China. China has about 50 percent of the world’s proved reserves and Brazil is second at about 35 percent. It drops off big after those two. This doesn’t mean production and consumptions, just what’s available for a battery industry that’s going to need a lot more graphite. The new development area is Africa. Madagascar presently and soon eastern Africa like Mozambique. The US doesn’t have much graphite in reserves and hardly produces any. It will soon be a big consumer from manufacturing to end us. Sourcing from all those countries mentioned above may be dicey in future. Or it may not. Sadly, graphite from petcoke isn’t of the quality battery manufacturers want. We have a lot of that from all the domestic refining we’re doing.

  • Otis11

    “Fueling up with renewable hydrogen would turn the tables, at least for the near future. Despite their well deserved points for cutting greenhouse gas emissions at the tailpipe, in the US many grid-charged battery EVs still depend at least partly on natural gas as well as coal.” – Ah, so would hydrogen vehicles… because unless I understood this wrong, this is making hydrogen from electricity (albeit at a reduced cost), so if EVs are using FFs, so would the hydrogen vehicles.

    Though I do see advantages for this research – specifically in carbon based fuel generation (for the hardest battery holdouts, such as planes and deep back-ups) and more importantly, fertilizer production. We use an incredible amount of NG to make fertilizer… which we aren’t going to get off of any time soon. This would help replace the NG part of that equation.

    Particularly, if they can do this with very low Capex, then they can use this to levelize the grid – use excess energy to produce hydrogen for fertilizer/synthetic carbon-based fuels, and turn it off when other sectors need the energy. This doesn’t work with most energy intensive industries because of the capex, but possibly could work here…

  • Ben The Mechanic

    Who cares about efficiency when renewable energy is being dumped due to its intermittent nature and unexpected spikes? Or who cares about natural gas being used for SMR when enormous loads of excess natural gas are getting burned off as unwanted excess because there’s no market for it?

    Do some research; the Bakken lights up the night sky like a bi-city Metro because of the enormous flares burning 24/7 consuming the excess gas being released while they frack away for OIL (the main constituent for gasoline). The Eagle Ford in south Texas suffers this same problem. Again – see the night-time satelite photo’s if you don’t believe me….

    • Otis11

      Well, they don’t burn off the NG because there’s no market for it, they do it because there’s not a profitable way to get it to market (No pipeline, port or immediate use in the vicinity of extraction).

      Also, they often flare NG in order to dispose of all the H2S produced – it unfortunately doesn’t burn very efficiently on its own, but a mixture of H2S and NG burning will yield SO2, water, and carbon dioxide.

      NG is very valuable, just hard to transport…

    • rockyredneck

      Yes, yet some say Canadian crude is more carbon intensive. Notice that fort McMurray has virtually no flares. I suspect with a true accounting, the Bakken produces more CO2.

  • JamesWimberley

    Let’s trust that Senator Inhofe will get the reception in Paris he deserves: as a laughing-stock. I hope some enterprising fly-on-the-wall documentary film-maker will be following him around and recording his conversations with the thousand people there who, unlike him, understand what is at stake.

    Tina: it’s not about the cars. The measly $2.8 million (out of $125 million) going from ARPA-E to fuel cells marks a correct distancing from a technology with ever fewer prospects. P2G may be important, sure: in providing renewable fuel for peaker gas turbine generators (see latest Agora study), and feedstock for liquid aviation fuel and petrochemicals.

  • Joseph Dubeau

    Once you turn “Power to Gas” to a hydrocarbon it can not be used in Hfcv.
    I like reading about this technology, but word “fvc” has become to politicize.

  • Marion Meads

    The major advantage of sun/wind to liquid fuel is that the energy stored in the fuel has the least cost of storing the fuel. We already have existing infrastructure for storage and distribution. The only investment needed would be reformation technologies involved, in order to produce drop-in fuels and other products.

    The most important part of the article is as usual missing, just like the bottom line prices are always missing for the new cars being featured. And in this case, the overall efficiency of the current state of the arts.

    The major problem is that the overall efficiency from the sun to the liquid fuel via solar PV to chemical reformation to drop-in liquid fuel could be worse off than getting drop-in replacements from sun to plants such as the algae biofuel. It would be nice to know the current of the state of the arts of the overall efficiency of sun to fuel or wind to fuel.

    Still nothing beats the solar energy or wind energy into battery energy storage when it comes to overall efficiency.

    • johnBas5

      Good point there is basically no information available about the energy efficiency or intensity of different CO2 capture methods.
      (For the reactions with water to hydrocarbons the situation is much better though still lacking. Chemical reactor efficiencies and processess seem to have some efficiency numbers available.)
      http://www.bren.ucsb.edu/news/geyer_pv_biofuels.htm
      Photovoltaics Beat Biofuels at Converting Sun’s Energy to Miles Driven
      New study shows solar power is not only better in terms of energy efficiency,
      land use, and greenhouse gas emissions – but is cost competitive, too

      “PV is orders of magnitude more efficient than biofuels pathways in
      terms of land use – 30, 50, even 200 times more efficient – depending
      on the specific crop and local conditions,” says Geyer. “You get the
      same amount of energy using much less land, and PV doesn’t require farm
      land.”

      “Even the most efficient biomass-based
      pathway…requires 29 times more land than the PV-based alternative in
      the same locations,” the authors write. “PV BEV systems also have the
      lowest life-cycle GHG emissions throughout the U.S. and the lowest
      fossil fuel inputs, except in locations that have very high hypothetical
      switchgrass yields of 16 or more tons per hectare.”

      PV conversion also has lower GHG
      emissions throughout the life cycle than do cellulosic biofuels, even
      in the most optimistic scenario for the latter. “The bottleneck for
      biofuels is photosynthesis,” Geyer says. “It’s at best 1-percent
      efficient at converting sunlight to crop, while today’s thin-film PV is
      at least 10-percent efficient at converting sunlight to electricity.

      Finally, while cost was not a key
      component of the study, Geyer says, “The cost of solar power is
      dropping, and our quick calculations suggests that with the federal tax
      credit, electric vehicles are already competitive.”

    • JonathanMaddox

      Power-to-gas storage has roughly 50% efficiency in current implementations but much of the losses consist in compressing the synthesised fuel to gas main pressure, which is not really a necessary step as many electrolysers will happily operate at elevated pressures, and the methanation step (if required) works only at high pressure.

      An optimised power-to-gas system with advanced solid oxide electrochemical cells has been designed (not built) which can achieve 70% round-trip efficiency, comparable to that of pumped hydroelectric power storage.

      http://orbit.dtu.dk/en/publications/largescale-electricity-storage-utilizing-reversible-solid-oxide-cells-combined-with-underground-storage-of-co2-and-ch4(756c6f2e-6c04-4b07-b894-9c386172ae19).html

      N.B. that when we’re talking about storing solar and/or wind electricity generated in excess of instantaneous demand, storage is going to be taking advantage of arbitrage spreads between off-peak and peak spot electricity prices. And the point of power-to-gas is to enable long-term, even *seasonal*, storage of excess springtime power for subsequent use in the dark, still winter. Round-trip energy efficiency matters less than the capital cost per unit capacity, which will be vastly lower with large-scale P2G facilities than with higher-efficiency technology such as batteries, which are admittedly a better solution for most other applications.

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