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@SJC, Liquid H2 does not require pressurization. PEM FC has much higher power density and is much cheaper per kW. LH2 maybe cheaper thanDME.
The answer for this problem is clear: Liquid Hydrogen powering fuel cells. The locomotives already have e-motors, so this should be cost-effective.
@Henrik, Please kindly do the math for the Boeing 777 and 787 when converted to LH2 to see how it would work. The Tu-155 is a very old and inefficient plane using very-low-bypass hence inefficient engines, with less-efficient aerodynamics. Modern Boeing 777, 787, and Airbus A380 are far more efficient and consume far less energy per passenger-mile, hence making LH2 feasible. The topic of this article is about electric small planes aka general aviation. In this regard, a LH2-FC propulsion system will prove to be far more efficient with regard to range and payload. An H2-FC powered quadcopter can fly 2-4 times longer than a battered-powered quad-copter, and ditto for H2-FC powered industrial forklifts, and the industry is gravitating toward H2-FC-powered large equipment for the same reason. Nikola Motor is choosing LH2-FC for propulsion of its electric semitruck, even though the truck also sport a humongous 320-kWh battery pack as power buffer. Please regard battery as being analogous to RAM in a PC while H2 is the Hard Drive Memory that is much cheaper and can be packed in much large amount. For commercial aviation, why not aim higher and work on Hypersonic planes, Powered by LH2 and ScramJet engine that can travel from NY to Tokyo in 2 hours? The LH2 will be circulating through the skin surface of the place to absorb heat before being burned off in the ScramJet engine. Everything else will be obsolete. For shorter range, there will be Fast Electric trains and Hyperloop. Please kindly forget about Li-ion battery for aviation and kindly regard LH2 as the new fuel for the dawn of Renewable-Energy and Zero-Emission Aviation. The ultra-lightweight of LH2 is the biggest asset that any aerospace engineer would kill to obtain. Tremendous weight reduction will lead to unprecedented level of efficiency. The LH2-FC can be regarded as a much, much lighter battery and much higher energy density than Li-ion can ever attain.
>>>>>>>>>"@Roger you can’t retrofit a hydrogen powered aircraft from an existing aircraft. " Yes, you can. I've done all the calculations, taking into account the volume of LH2 required and the volume under the seating floor of an airliner. It is entirely possible without any loss of passenger space nor cargo space. You can try to do it yourself if you care to. However, to really save more fuel and save energy and save internal space by reducing the volume of LH2 fuel, a re-design will be necessary to incorporate smaller wings, smaller tails, smaller engines, and smaller wheels and landing about 60% the size of the kerosene-powered aircraft to adjust to the much lighter weight of the LH2. Only the fuselage will need to remain the same. With this type of re-design, it only takes 30% of LH2 fuel energy to fly a long-range aircraft for a given cargo weight as compared to using much heavier kerosene. On a long-range flight, 66% of the useful load weight is fuel weight when using kerosene. Using LH2 on an aircraft optimized for LH2, the proportion of fuel weight WRT useful load is only about 30%.
@Dr.Strange Love, Apparently, the lifespan of the LH2 tank should be good enough for Nikola Motor to consider the use of LH2 in semi-trucks. Furthermore, the LH2 tank can be designed to be easily removed and replaced at regular intervals to ensure safety. Having a thin aluminum inner layer and polyurethane foam outer layer should be cheap enough and light enough. Boil-off rate is insignificant at the size of LH2 tank required for an airliner. The APU (auxillary power unit) (which could use a fuel cell) can use the H2 evaporating to make electricity and have a plug-out to power the airport and the city as well, while the plane is parked, until the next flight. NASA study showed that a LH2 spherical tank a foot in diameter with 1" foam insulation takes about 6-8 hrs for complete boil off. If you triple the insulation thickness,it would take a whole day for boil off, and with ten-fold volume to surface ratio, it would take 10 days for complete boil off. @Henrik, Please read my reply to Dr. SL above for concern about LH2 tank durability and boil-off. Just use the LH2 in existing jetplanes would be the cheapest option. Designing new airliners takes $10 Billions, like the Boeing 777, that use conventional turbofan tech. Designing a completely novel and unconventional system may cost a lot more than that. Due to the much lower loaded weight of a LH2 jetplane, the wings, the tails, the landing gears, and the engines can all be around 60% the weight of previous sizes, causing even further reduction in airplane gross weight and hence even lower fuel consumption...probably 30% the fuel consumption per mile in comparison to a kerosene powered plane for a given payload weight, so you can actually save on fuel cost...You pay double for fuel cost per energy unit but your plane only consumes 30% of the energy per mile. @Harvey, LH2 seems to be the best option for both small aircraft as well as for the largest airliners. At the end of a flight, any LH2 remaining in a small aircraft can be pumped out, and the plane can taxi back to the hangar using battery power. Of course, electric trains will save more energy than jetplanes, but we're discussing air travel here.
@Henrik, Dr. Strange Love must have referred the 115:1 energy:weight ratio as between Liquid Hydrogen (LH2) vs Li-ion battery at 400 Wh/kg, though getting 40 kWh per kg HHV of H2 divided by 0.4 kWh/kg of Li-ion would only give 100:1 ratio. But please know that LH2 is the future of aviation, due to the extreme weight advantage of LH2 vs kerosene jet fuel, of 3:1. Foam insulated container for LH2 is very light, as used in NASA's rocket. The reduction in fuel weight itself will double the payload:fuel for airliners and airtransport planes. The H2 can simply be burned in current jet engines with some modification, at around 50% thermal efficiency, which is comparable to the efficiency of the latest large-size turbofans. With LH2 costing $4 per kg and JP4 costing around $2 per gallon, the fuel cost per lb of payload is comparable. @ECI, Look to LH2-FC electric power as a way to significant boost payload capacity of General Aviation aircraft. Imagine carrying 1/5 the fuel weight for comparable range, for example, 500 lbs of AVgas fuel can be reduced down to 100 lbs of LH2 to travel 1,000 miles in LH2-FC electric aircraft! How is that doing for your payload capacity, eh? Your 2-occupant aircraft at full fuel load now can carry 4 adult occupants with luggage to travel 1,000 miles. NASA is paying about $4 per kg of LH2. So, you can carry twice as much payload while paying 1/2 for fuel cost, or FOUR-fold payload to fuel cost ratio.
@ECI, It only takes about 1,000 H2 stations for the entire USA to ensure a median driving distance of 4 miles from home to the nearest H2 station in urban and suburban areas. At the latest cost of $1 Million per station as mass-produced by Nel Hydrogen in factory, the price tag of the initial H2 station network will be only $1 Billion. If each of the 5 automakers who are making FCV's or planning to make FCV's would share this cost, each will only have to fork out $200 Million. There is no need to have 120,000 H2 stations in the USA to make FCV practical for urban and suburban dwellers. Only 1,000 initial H2 stations costing $1 Billion would suffice.
@msevior, You do have a good point, however, the cost of H2 won't double as you projected. Here's why: 1) The capacity factor of wind in the USA is around 34%. New wind turbines with much bigger blades can produce power with less wind, hence can have capacity factor around 40-50%. 2) Combined solar and wind will raise the capacity factor, especially if half of the solar power can be fed to the grid during peak grid demand during the day, leaving the most of night-time wind for the electrolyzer. So, you would build out twice the solar capacity of the grid daytime demand, and on sunny day, use half of the solar PV power to make H2. On cloudy days, all of the solar PV output can be devoted to the grid. The combination of solar and wind can raise the capacity factor to above 50%, which is quite close to the 70% utilization factor in the cost calculation. 3) The H2-production facility includes power-handler, electrolyzer, purifier, low-pressure storage facility, H2 compressor and high-pressure H2 storage, and necessary piping. Assuming 50% combined wind and solar capacity factor, then the power handler and the electrolyzer will be used only 50% of the time, but the rest of the facility can be sized so that they can be utilized nearly 100% of the time. For example, inexpensive low-pressure H2 storage can store intermittent H2 production to be fed to the H2 purifier and H2 compressor and H2 dispenser that can be sized so that they can be utilized nearly 100% of the time. When considering all the above factors, the cost of H2 facility will not exceed much of the cost calculation using 70% utilization factor in the H2 cost estimate by ITM Power, even when using RE with combined capacity factor of around 50%.
@msevior, ITM Power reported Hydrogen cost of £2.69/kg (US$4.13/kg)... after capital amortization, at 70% utilization, with electricity cost of 5c/kWh and 55 kWh per kg. With the new-low electricity cost of 3 cents per kWh, we can expect a cost reduction of $1.10 per kg, thus only $3.03 per kg. Within a 10-year capital amortization period, £4.19/kg (US$6.44/kg) with electricity cost of 5c / kWh. With electricity cost down to 3 cents per kWh, the H2 cost will go down to $5.34. If we assume that the electrolyzer will continue to last for 10 years more after the 10-year amortization period, then the H2 cost will be the average of the $5.34 and the $3.03 = $4.18 per kg. To be cost-competitive with gasoline in the USA, the H2 can be priced at the pump at $6.8 per kg, so that will give a profit margin of about $2 after a $0.50 of fuel tax. Conclusion: Retail price of H2 for FCV at the pump made from the new-low costs of solar and wind electricity will soon be cost-competitive with gasoline on per-mile basis.
The good news now is that Solar and Wind (S&W) electricity is coming down on par with the prices of Fossil Fuel (FF) power plants. However, intermittency and non-dispatchability of S&W render new S&W unable to substitute for new FF power plants, unless e-storage or natural gas backup power plants are also built. The problem with energy-storage systems is that they will double or triple the cost of Solar and Wind (S&W) electricity when energy-storage is employed in conjunction in order to make S&W reliable 24/7 source. Even worst, battery and pumped hydrostatic storage have very limited capacity that will be depleted after more than one or two days of dark clouds and little wind. For this reason, Solar and Wind must cost-effectively depend on stand-by natural gas power plants that are already paid for. This will significantly affect the growth potential of S&W. For example, if a community will need 300 MW of new generation capacity, that community cannot depend on S&W alone, but must build out additional ~250MW of natural gas power plant for use when combined S&W is very weak. This will significantly increase the cost of new S&W capacity and will make S&W much less competitive. However, if we now shift strategy and employ Solar and Wind (S&W) to make high-value transportation fuel instead, then perhaps the economics may look more compelling. At 3 cents per kWh and 55 kWh per kg of H2 at the pump, the raw energy cost will be only $1.65. Adding $2 to cover the cost of H2 production facility, distribution cost and operational cost, then 1 kg of H2 at the pump can have a pre-tax-and-profit cost of $3.65 per kg. Adding profit and tax to this to price this S&W H2 to $6.8 per kg at the pump, and this will still be cost-competitive with gasoline car with 25 mpg and gasoline at $2.5 per gallon, when used in the Honda FCX Clarity at 68 MPGe, when both will have a fuel cost per mile of 10 cents. Subtracting $3.65 from $6.8 = $3.15, and assuming 50 cents tax per kg of H2, will give a profit of $2.65 per kg of H2. Dividing this $2.65 to $6.2 pre-tax price = 43% profit potential. This is very good, considering profit margin for the major oil companies to be around 23%.
Sorry, Harvey, but the Least Significant cars will be the FCEV's, while the PHEV's will be the most significant cars, according to a Twitter survey by GCR.
Ok, geniuses, this is how one can take advantage of this wonderful discovery: Expose the chemical to sunlight together with electron donor source, pump away those exposed chemical, then separate out the radicalized molecules in the dark and generate hydrogen and then pump out those de-radicalized molecules again to the light. What the above has accomplished is the elimination of solar PV AND of electrolyzer which are both costly, and replace with just translucent tubing running on top of any roof to circulate the chemical while being exposed to sunlight. A potential to eliminate H2 storage tank and the H2 compressor, if the sun-exposed radicalized molecule collected during the day can be turned directly into H2 on-demand later for used in home-based fuel cells that can generate both power and heat. Power to run the house lights and appliances, while the waste heat from the FC unit can make hot water for bathing, laundry and dishwashing. Since it is easier to store liquids at ambient pressure than to store H2 at high pressures, this can replace the Tesla Powerwall for daily storage of solar energy to be used later in the evening.
With new stuffs, you sometimes have to give 'em away to get people to get hooked to 'em. And get hooked, they will.
A serial hybrid suffers from losses from generator, at 95% efficiency, then inverter at 95% eff then motor 95% eff for total efficiency of 85%. A parallel hybrid like the Prius has 3/4 of the torque directly mechanically transmitted from the engine with zero loss, and only 25% via motor-generator route at 85% efficiency. The 1.2-liter engine with 10.7 compression ratio can best manage 34% thermal efficiency, while the Prius' engine can manage 40% thermal efficiency. The Versa Note has lower aerodynamic efficiency than the Prius. Overall, should have lower MPG than the latest Prius due to lower-efficiency items as above, such as losses in the motor-generator route, lower-efficiency engine, and lower aerodynamic efficiency. The e-Note has a 109-hp motor plus a 80-hp generator, for a total of 189 hp of e-power. The Prius has only a 70-hp e-motor plus a 25-hp motor-generator, for a total of 95 hp of e-power. The Note has a 1.5 kWh battery pack while the Prius has only a 0.75 kWh battery pack. Though the engine is only a 3-cylinder which may cost $500 less than the Prius' engine, and the lack of the planetary power-split unit may save another $500, though the doubling of battery capacity may cost around $500 more. while the doubling in e-power and in battery capacity will cost thousands more. At roughly ~$35 per hp of e-power, the 95 hp excess of the e-Note may raise the price by $3,325. Over, the e-Note may cost Nissan around $2,500 more than that of the Prius, on the price tags, due to excess amount of e-power and of battery capacity. Profit margin to Nissan probably won't be as much as that of the Prius, if both cars are priced at the same amount. Yet, the e-Note can put out only 109 hp max, vs 121 hp of the latest Prius.
Buen punto, Centurion. Se necesita una gran cantidad de dinero y recursos para desarrollar totalmente una nueva química de la batería, después de un montón de pruebas. El hecho de que esta se desarrolla en China, donde existe un fuerte incentivo para avanzar hacia la electrificación, y no hay industria del petróleo y el gas dominante, ni industria del motor de combustión, lo haría más probable que tenga éxito.
@mahonj, Well, as you can see, there is enough room for 5 seats, but the load capacity reduction due to the much heavier 8.8-kWh battery pack vs the 0.75-kWh battery pack of HEV Prius would not safely permit carrying 5 typical adult Americans nor Europeans. The curb weight of the Prime is 1510 kg, or 3322 lbs. The weight of a Prius level 2 is 3,075 lbs. The weight difference is 247 lbs, and as much as 300 lbs, depending on trim level and optional equipments. It would not be economical to alter the Prius Prime body, chassis and suspension drastically to accept this much weight difference for a much smaller production volume of the Prime, hence the reduction in passenger capacity,in order to keep the price of the Prime to competitive level. Furthermore, with more weight on the rear wheels than on the front wheels, you will have problem with oversteer on a high-G turn which will lead to loss of control, even when you install bigger springs on the rear axle. Plus, Toyota will have to redo crash testing and other safety certifications following major alterations in max gross weight rating and weight distribution, which will be expensive for the low production number associated with typical Plug-in EV's. May not pass crash testing, which may necessitate re-enforcement of the frontal structures...more weight and cost. A solution for making a 5-seat Prius PHEV is to save 150 lbs in the front axle by using a much smaller and lighter engine from the Toyota Aygo, a 3-cylinder 1-liter Atkinson cycle, capable of 70 hp with 37% thermal efficiency, and to move the battery pack to under the front two seats, to reduce weight on the rear axle. A further 43 lbs of weight can be saved in the rear axle by reducing the fuel tank from 11 gallons down to 5.5 gallons, for a total of 193 lbs of weight reduction. This will permit 3 adult passengers on the rear seat with a full 27 cu-ft of trunk space.
A higher-temperature PEM electrolyzer cell can use steam instead of water, thereby can shave off 6 kWh off of the 50 kWh to make 1 kg of H2. This is because it takes about 6 kWh of energy per kg of H2 produced, to turn liquid water into steam, before the steam can be separated into gaseous H2 and O2. Thus, the waste heat of the electrolyzer can be used to turn water into steam, then the steam will take only 44 kWh of electricity to make 33 kWh in 1 kg of H2. Thus, the efficiency of electrolysis will be raised from 66% to 75% for H2 at LHV (Lower Heating Value) to use as a fuel, or to ~90% for H2 at HHV (Higher Heating Value) when the H2 will be used for space heating. High-efficiency electrolysis will make H2-E-storage medium just as efficient as battery for combined heat and power applications, with round-trip efficiency at nearly 90%.
>>>>>>>>>>"If fuel costs can be cut in half by switching to electricity,..." Can it? Daimler-Benz Supertruck attained 12 mpg, with a thermal efficiency of 50%. 1 gal of Diesel #2 contains 38 kWh of energy, LHV. So, in one hour at 60 mph, it consumes 5 gallons x 38 kWh = 190 kWh of energy at 50% efficiency. An electric power train achieves about 80% efficiency (0.93^3 for battery eff x motor eff x inverter eff), so would consume 190 /80 x 50 = 119 kWh of electricity. 5 gallon of diesel fuel at $2.15 = $10.75 119 kWh of grid electricity at $0.13/kwh US average = $15.70 Daimler-Benz Supertruck probably is not cheap, but an equivalent electric truck with battery for at least 200-mi range is not cheaper, neither. Cummins & Peterbilt Supertruck can attain 10.7 MPG, using less technologies, so would still have lower fuel cost than electric truck, with lower acquisition cost than Daimler Supertruck. Future Hydrogen Fuel Cell Semi-Truck at 12 mile per kg, and future Hydrogen at $4 per kg will cost $20 per hour, $3.30 per hour more than electric semi truck, yet is capable of 100% Renewable Energy and zero emission.
Fischer-Tropsch is known to be both inefficient and expensive process. The use of CO2, either from power plant exhaust or from the air, is also not cheap. It would be more efficient and far cheaper to use waste biomass for pyrolysis combined with hydrogenation (addition of H2) all in one step, (aka hydro-pyrolysis) to produce a bio-crude equivalent to petroleum crude oil that can be refined into various hydrocarbon fuels. Look up Purdue University for detail of this process. Previous estimates placed this bio-fuel from biomass hydro-pyrolysis to be competitive with gasoline at $3.50-$4.00 per gallon. Not yet competitive with current-day gasoline at $2.5 a gallon, but perhaps a Federal Mandate can require gradually increasing percentages of RE in ALL of our energy supplies annually. This will force a gradual growth in RE in our energy supply, that in time, will become cheaper and cheaper due to experience and economy of scale, in order to totally replace fossil fuels in due time. The Hydrogen here can come from grid-excess Solar and Wind electricity in order to give predictable return for Solar and Wind investors, in order for Solar and Wind to grow and fulfill even over 100% electricity grid penetration. The Hydrogen can also be used directly for FCV's and for home and office heating and home-based Fuel Cells.
If this type of SOFC will replace the PEM-FC in current-day FCEV, then FCEV's will grow real fast, because FCEV's as is being produced today can also use Compressed Natural Gas and Propane beside H2, at thousands of locations in the USA. However, to promote the growth of RE, there will have to be a Federal Mandate requiring increasing proportion of RE content, that can be H2 made from grid-excess RE, in the CNG + H2 mixture, in order to give predictable return of investment for RE investors, so that RE will continue to grow even to past 100% for the electric grid. Not mentioned anywhere is the power density of this type of SOFC. Sure hope that it will be good enough for mobile application.
>>>>>>>eci stated: "Well, it is competition in the sense that a typical person will choose between a BEV, PHEV or FCV, whether or not that FCV has a larger battery and plug." A Plug-in FCV (PFCV) is two vehicles in one: A short-range BEV and a FCV, so you can have a BEV and a FCV all in one vehicle. No need to choose there. A PHEV is two vehicles in one: A short-range BEV and an ICEV all in one vehicle. No need to choose there. How about choosing between a PFCV and a PHEV? 1) Many people driving a PHEV have "engine-start anxiety". They feel bad when the engine started and feel bad for having to rely on the engine. A PFCV will solve that problem. Both the battery and the FC will blend in harmoniously and seamlessly unnoticeable by the driver. 2) H2 gives the ability to drive on 100% RE, while a BEV has only 13% RE content average US grid mix, and a ICEV has only 10% ethanol in gasoline, but, since corn farming is fossil-fuel intensive, true RE content of ethanol is much lower. A FCV has much higher green credential than a BEV or a HEV or a PHEV. 3) Home power back up while parked in the garage is possible with a FCV, but not with a PHEV due to exhaust fume accumulation and risk of CO toxicity and death. 4) Permitting the grow of RE to well past 100% in the grid, when grid-excess RE can be used to make H2 and bring back predictable revenue for RE investors. Only FCV and PFCV can do that. PHEV's do nothing to help ensure continual growth of RE. 5) Fuel Cell and e-motor can be modular in nature, so a car maker will not have to design a new engine and transmission, which can be very costly, plus new emission certification for each new car. Small FCV's may have one FC stack, mid-size FCV's has two, and large FCV's have 3 FC stacks, etc. Same with big trucks. No need to spend a fortune to design a spanking new diesel engine every time a new model is released. This will help reduce the cost of new car and truck development and will make FCV cheaper than ICEV in the future.
I must hasten to add to the above that with wide-spread Solar PV carport charging for the PFCV that can bypass the grid completely, then the grid will be spared of PEV charging at night, when the power transformer must cool off to get ready for another hot summer day, without having to use less-efficient Hydrogen reserve. So, widespread Supercharging of long-range BEV on a hot summer day with power drawn from the grid is not in the best interest of grid stability. A PFCV has the advantage of being capable of using H2 during the grid's peak power demand, hence sparing the grid from brown out. A PFCV has the advantage of capable of being charged with Solar PV carport energy during sunny days, while not being charged during cloudy days. The solar car-port DC charging socket will not supply energy during low-solar-energy day, thus will not add burden to the power grid. However, if you have a BEV and must drive a lot that day, you have no other option but require SuperCharging, thus adding on to the power demand burden of the grid during periods of peak demand. Even worse, SuperCharging must also go on during periods of low Solar and Wind, forcing back-up power generation on the grid that is expensive to invest and to maintain. With a PFCV, your FC on board is your backup power generator, and completely spare the grid of excessive power demand nor of requiring expensive backup power generation capacity.
>>>>>>>>eci stated: "It will be very interesting to see if the prospective technology you describe can economically compete with the much simpler and safer electric distribution grid, solar, and batteries." It is NOT a competition. It is a cooperation. 1) We will still need the electric grid like we do today to transmit Solar and Wind electricity as it is being produced in real time. This is the most efficient way and least expensive way to use Solar and Wind (S&W) electricity. In the Springs and Falls, you will charge your Plug-in FCV (PFCV) with those abundant S&W electricity to get the highest efficiency out of it. Any excess S&W electricity in Springs and Falls will be used to make H2 and stored away in vast underground reservoirs. 2) Now, then, we will have winters with cloudy days and shorter days and many low-wind days with a lot of electricity demand for lighting and industrial use PLUS the need for home and office heating. That's when the H2 underground piping will come into play, with home-based Fuel Cells (FC) to provide both power and heat, or just heat when not a lot of power is needed. Of course, you will charge your PFCV on a winter night using the electricity from a home-based FC, while releasing the waste heat to keep your house warm. However, if there is a need to keep the windshield and the cabin warm while on the road, to avoid ice re-accumulation, then you will power your PFCV initially with H2-FC whenever waste heat will be necessary. You will use battery power when heating will no longer be needed. Or, you just turn on the FC a little bit to get just the amount of heat needed, while use battery power to supply the rest of power demand of the car. 3) We will have many very hot summer days and summer nights with low wind and very high electricity demand, even late into the nights when people sleep, they crank up their A/C to beat the heat and humidity. During those times, the PFCV will NOT be charged from the grid, but will use Hydrogen made from other seasons for power to spare the grid of being overloaded. Those overhead transformers will blow if overheated, so summer heat won't help. Of course, a better strategy for shifting day-time solar energy into night-time cooling would be the use of thermal cold storage (Ice). You make the ice using daytime solar energy, then use that ice to cool your house in the evening. But, we can't count on all the houses will have this thermal ice e-storage. So, the best strategy is not whether battery or H2-FC, but BOTH. Battery energy or direct S&W whenever heat is not needed, while H2-FC energy when waste heat is needed. Even in the summers, you will need to hot water for dish washing, laundry, and bathing. Thermal ice storage can handle A/C needs during summer evenings and nights.
No need for high-pressure home tank. When the home Natural Gas piping will be converted to Hydrogen, then the H2 produced will just go down the piping and the meter will run in reverse to give you production credit, kinda like net metering. To fill up your FCEV, a small compressor can use the very low-pressure home H2 piping to compress over night, just like charging your Plug-in EV. A home-based Fuel Cell can give out waste heat for hot water and home heating, thus can elevate the efficiency of H2 to nearly 100%. With modern electrolysis at over 80% efficiency on Higher Heating Value, the round-trip efficiency of H2 production and consumption can be as high as 80%, to be competitive with other forms of e-storage.