As part of the quest of having energy sources that produce near-zero CO2 emissions, energy systems analysts have looked at hydrogen as one such source. They see hydrogen as a possible fuel for transportation.
In California, the hydrogen economy movement has received support, in the form of subsidies and demonstration projects, from the state government and environmental groups, often supported and financed by prominent Hollywood actors.
Current Hydrogen Production: Hydrogen is used by the chemical, oil and gas industries for many purposes. The US produces about 11 million short tons/y, or 19958 million kg/y.
At present, about 95% of the H2 production is by the steam reforming process using fossil fuels as feedstock, mostly low-cost natural gas. This process emits CO2.
Hydrogen for Transportation: Proponents of H2-powered fuel cell vehicles, FCVs, in California think the hydrogen economy will be the future and a good place to start to reduce CO2 emissions from internal combustion vehicles, ICVs, would be to have near-zero-emission vehicles.
Here are examples comparing the fuel cost/mile of an FC light duty vehicle, an E10-gasohol IC vehicle, and an EV:
- Honda Clarity-FCX, using electrolytic H2 in a fuel cell, mileage about 68 mile/kg, or 14.8 c/mile, at a price of $10/kg* at a fueling station in California. About $7/kg is electricity cost, and $3/kg is station cost. The H2 is not taxed. The average commercial electricity rate in California is 13.41c/kWh, which ranks 7th in the nation and is 32.9% greater than the national average rate of 10.09 c/kWh.
- Honda Accord-LX, using E10-gasohol, mileage about 30 mile/gal, or 8.3 c/mile, at a price of $2.50/gal at a gas station in California; this price includes taxes, surcharges and fees.
- Tesla Model S, using 0.38 kWh/mile, includes charging and vampire losses of batteries, at user meter, or 7.6 c/mile, at a price of 20 c/kWh at user meter; this price includes taxes, surcharges and fees.
Electrolytic H2 Production: H2 fueling stations can produce electrolytic H2 at high pressure on site with electricity at commercial electric rates, or H2 can be produced by central plants with electricity at industrial rates (typically lower than commercial rates) and delivered by truck to fueling stations.
The turnkey cost of fueling stations is well over $1 million per site, whereas a multi-bay EV charging station costs about $200k. In early 2017, there were (25) H2 fueling stations in California. FCV drivers must go to an H2 station to refuel. EV drivers have flexibility, as they mostly charge at home, or at work, or at public places, such as shopping malls.
Battery and H2 Storage: California generates significant solar electricity from about 10 am to 2 pm, almost every day, which stresses the electric grid and other generators. The state government has mandated utilities install battery storage systems to store some of that electricity for distribution during peak demand hours later in the day. The round trip loss of this set-up is up to 20%.
Central H2 plants likely would increased their H2 production from 10 am to 2 pm, if the state would mandate a low electric rate, of say 5 c/kWh, during those hours. This would reduce the need for expensive battery systems and provide lower-cost H2 to FCVs.
NOTE: Whereas EVs and FCVs do not have CO2 emissions, the grid electricity for charging the batteries and producing H2 does have CO2 emissions.
NOTE: The H2 lower heating value is 113819 Btu/kg, which is comparable to the E10-gasohol LLV of 112114 - 116090 Btu/gal. A kg of H2 is about equal to a gallon of E10-gasohol, on a Btu basis. However, H2-powered vehicles have about 2 times the mileage of ICVs, i.e., to displace 1.0 gallon of E10-gasohol, about 0.5 kg of H2 is needed.
NOTE: The purchase price of FCVs and EVs are significantly higher, than of equivalent ICVs, because they are produced in very small quantities per day, whereas ICVs are produced in the thousands per day.
NOTE: In 2015, about 140.43 billion gallons of gasoline were consumed in the United States, a daily average of about 384.74 million gallons.
Lay people are being led to believe the hydrogen economy, i.e., producing H2 by electrolysis from near-CO2-free sources, such as hydro, wind, solar, and nuclear energy, will be a reality in the near future. For that to be true, for this analysis, it is assumed mass production of H2 at a rate of about 375/2 = 187.5 million kg/d would be required.
Replacing Gasoline With Hydrogen For Light Duty Vehicles: Electricity required would be about 187.5 million kg x 60 kWh/kg = 11250 million kWh per DAY, or 4107 TWh/y, at H2 production plant meters, plus 7% for transmission and distribution losses, plus 4.5% for self-use, for a gross generation by power plants of 4107 x 1.07 x 1.045 = 4592 TWh/y, which would be in addition to the current US gross generation of about 4000 TWh/y. The US would need several times that quantity of electricity to produce H2 for powering many other such energy needs! Generating all that electricity with hydro, wind, solar, and nuclear energy would require enormous investments.
Future Production of Hydrogen: Replacing gasoline with hydrogen, just for light duty vehicles, would require an additional H2 production of about (187.5 million x 365)/19958 = 3.43 times existing production; it is highly unlikely this will happen.
Replacing Gasoline With Electricity For Light Duty Vehicles: Electricity required would be about 2,664,445 million miles/y x 0.38 kWh/mile = 1,012,489 million kWh/y, or 1012 TWh/y, at user meters, plus 7% for transmission and distribution losses, plus 4.5% for self-use, for a gross generation by power plants of 1012 x 1.07 x 1.045 = 1132 TWh/y, which would be in addition to the current US gross generation of about 4000 TWh/y. Generating all that electricity with hydro, wind, solar, and nuclear energy would require enormous investments, but much less than using electrolytic H2.
NOTE: At present, the A to Z electricity input (not just the process) for electrolytic H2 is up to 60 kWh/kg, depending on the efficiency of the system. The future wholesale prices of the electricity from hydro, wind, solar, and nuclear energy* likely would be 2 - 3 times current prices. That means, the efficiency of the electrolysis process would need to be significantly increased to reduce the cost of the electricity input.
*Those, mostly variable, energy sources would require greatly expanded, nationwide transmission system build-outs, plus distributed energy (thermal and electrical) storage system build-outs to ensure electricity and other energy supply throughout the US, 24/7/365, year after year.
Conclusion: Battery-powered EVs likely will be the dominant mode for light/medium duty vehicles, and for mass transit busses, delivery vehicles, like UPS, etc., in the future. China is building multi-billion dollar battery plants, similar to Tesla’s. H2-FCVs likely will be suitable in certain areas with favorable conditions, such as low-cost electricity.