Hydrogen Background

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'Types' of Hydrogen

Hydrogen itself is a colorless, odorless gas. It is the most abundant element in the universe and forms water when burned or reacted with oxygen.

Hydrogen 'colors' disguises the impact GHG emissions have with hydrogen production from different manufacturing processes. The hydrogen color spectrum can be summarized as.

  • Green - hydrogen made from renewable sources, essentially the electrolytical processes, using water and renewable energy such as wind and solar.
  • Blue - gray hydrogen with carbon capture and sequestration processing added.
  • Gray - hydrogen made from the methane in natural gas and other oil and gas products, mostly using Steam Methane Reforming.
  • Brown - hydrogen made from coal mostly via Coal Gasification.
  • Pink - hydrogen via electrolysis of water using energy from nuclear power.
  • Turquoise - hydrogen made using an unproven process called methane pyrolysis to produce hydrogen and solid carbon.
  • Yellow - hydrogen made through electrolysis using only solar power.
  • White - hydrogen is a naturally-occurring geological hydrogen found in underground deposits.

'Clean' hydrogen is an ambiguous phase meant to refer to any hydrogen production that has a net-zero or better GHG emissions 'footprint'. Sometimes it is used to refer to hydrogen made with low but not insignificant CO2 emissions, compared to fossil-fuel hydrogen.

Renewable hydrogen is made from renewable energy and water. It is the same as 'green' hydrogen.

Fossil-fuel hydrogen or fossil-hydrogen is made from methane in natural gas and other oil and gas products. It is the same as 'gray' hydrogen.

Note, until all manufacturing, storage and transportation industries and so on have been decarbonized, all hydrogen production will have some life-cycle carbon footprint.

Blue Hydrogen Briefing

A Blue Hydrogen Briefing by Tom Solomon of 350 New Mexico was presented to a meeting of the NMSEA on November 16, 2021. It is now available on YouTube. The 42 min talk itself starts at the 5:30 mark, with Q&A starting at minute 47.

Also the slide deck now includes a new slide on p18 with now a second scientific study warning about the climate impacts of producing hydrogen from methane.

Highlights include: [content in preparation]

Chemical Composition of Natural Gas

Natural gas is a naturally occurring gas mixture, consisting mainly of methane sourced from supply basins in the Four Corners and Permian Basin in New Mexico

Composition is an overall system average and may vary from the typical value listed below by location.

Component Typical Analysis (mole %) Range (mole %)
Methane 94.7 87.0 - 98.0
Ethane 4.2 1.5 - 9.0
Propane 0.2 0.1 - 1.5
iso - Butane 0.02 trace - 0.3
normal - Butane 0.02 trace - 0.3
Propane 0.2 0.1 - 1.5
iso - Pentane 0.01 trace - 0.04
normal - Pentane 0.01 trace - 0.04
Hexanes plus 0.01 trace - 0.06
Nitrogen 0.5 0.2 - 5.5
Carbon Dioxide 0.3 0.05 - 1.0
Oxygen 0.01 trace - 0.1
Hydrogen 0.02 trace - 0.05

Properties of Natural Gas

A selection of physical properties of natural gas are included below.

Property Typical Analysis Range
Specific Gravity 0.58 0.57 - 0.62
Gross Heating Value (MJ/m3), dry basis * 38.8 36.0 - 40.2
Wobbe Number (MJ/m3) 50.9 47.5 - 51.5

﹡ The gross heating value is the total heat obtained by complete combustion at constant pressure of a unit volume of gas in air, including the heat released by condensing the water vapour in the combustion products (gas, air, and combustion products taken at standard temperature and pressure).

Sulphur may vary from 3 - 6 mg/m3 depending on the field.

Water vapour may be less than 65 mg/m3 and can vary from 16 - 32 mg/m3 depending on the field,

Typical combustion properties of natural gas:

Ignition Point: 564 oC * Flammability Limits: 4% - 15% (volume % in air) * Theoretical Flame Temperature (stoichiometric air/fuel ratio): 1953 oC * Maximum Flame Velocity: 0.36 m/s *

﹡ The properties shown may vary depending on the location. Information provided is from the Ortech Report No. 26392, Combustion Property Calculations for a typical Union Gas Composition, 2017.

Water Consumption

Here's a heavily referenced article from EnergyPost.eu on research into how much water will be needed in the production of hydrogen through electrolysis (green hydrogen). Some quotes from the summary:

"Assuming the world is using over 70EJ of electrolytic hydrogen by 2050, the water consumption will be about 25 bcm. That is relatively small compared with the global figure of 2,800 bcm for agriculture (the largest consumer), 800 bcm for industrial uses, and 470 bcm for municipal uses."

"the numbers suggests that water consumption shouldn’t be a major barrier for scaling up renewable hydrogen"

The same article reports that methane reforming uses a similar amount of water per kg H2 as electrolysis! There are life-cycle comparisons included too for five hydrogen pathways, e.c. wind->electricity->hydrogen

But, it says, the water has to be desalinated for electrolysis to avoid degradation of the electrolysis cells. And then, that water costs including treatment would only cost 2% of a best case total renewable cost of $2-3/kg H2. Fossil fuel hydrogen today (2021) is available at $1.80/kg H2, some current renewable numbers are up to $5/kg H2. Under the Biden Admin the DOE has a target to get costs down to $1/kg H2 by 2030.

Falling Costs

S&P Global report that falling green hydrogen costs are closing in on fossil-fuel hydrogen costs.

Plans for GW Electrolyzer Factories

Electrolyzers are essentially the cells where electrolysis of water is contained producing hydrogen and oxygen.

S&P Global reports (Nov 9 2021) that the UK company ITM Power is planning to build a second electrolyzer factory to make renewable hydrogen production equipment as it prepares for rapid market expansion. The 1.5 GW/yr facility adds to their existing 1 GW/yr.

Recharge reported Jan 4, 2022, US company Cummins plans to build a 1GW hydrogen electrolyser factory in China with state-owned oil giant Sinopec

Earlier, dated May 24 2021, Recharge reported that Iberdola and Cummins had plans to build a fourth electrolyzer gigafactory in central Spain.

"The €50m ($61m) proton exchange membrane (PEM) electrolyser plant will start up in 2023 in the central region of Castilla-La Mancha, near Madrid, as a 500MW-a-year facility, “and will be scalable to more than 1GW/year”, according to Cummins.

It is the fourth electrolyser gigafactory to be announced in Europe this year, following in the footsteps of the UK’s ITM Power, Norway’s Nel and France’s McPhy. Denmark’s Haldor Topsoe has also unveiled plans for a 500MW plant producing high-efficiency high-temperature solid-oxide electrolysers."

Other electrolyzer manufacturers have also announced giga-scale factories, including Germany’s ThyssenKrupp (5GW), Norway’s Nel (2GW), US compatriot Plug Power in conjunction with Australia’s Fortescue Future Industries (1GW), and France’s McPhy (1GW).

Industrial Hydrogen Uses

The WHA(World Hydrogen Association?) reports on industrial hydrogen uses worldwide: 25% petroleum refining, 55% ammonia (thence to fertilizer), 10% methanol and 10% other that includes fuel cells, glass, electronics, medical, food and metallurgical uses. In a transition away from fossil fuels the petroleum refining segment will decline but still leave considerable demand in other sectors.

NOx Emissions from Burning Hydrogen in Air

The amount of NOx emissions when burning hydrogen in air either for industrial or residential purposes depends on many factors. NOx are greenhouse gases so their generation should be minimized. NO2 has a molecular weight of 46 making it denser than air (avg MW 29.87) while NO is MW is 30, about the same as air, N20 MW is 44.

Some proposals include adding hydrogen to fuel gas in for example industrial furnaces. NOx generation is discussed in this article from The Chemical Engineer and discusses the factors involved, e.g. burner design, flame temperature and such. Since NOx emissions are legally constrained in some jurisdictions, burner design plays an important role to meet such specification.

Diesel and gasoline internal combustion engines are a major source of NOx emissions.

Permeation Rates

Permeation rates of hydrogen in various storage configurations has been reported. During some safety investigations, researchers reported the following leakage rates:

"Based on the data provided by the manufacturers, the hydrogen permeation rates of the hydrogen storage vessels of vehicle A and B were approximately 2.35 mL/min and 1.80 mL/min, respectively."

One presumes the volumetric measures corresponded to standard temperature and pressure conditions (STP).

Hydrogen tanks in trains, boats, planes and cars are made of carbon fiber and run around 10,000 psi their NWP (normal working pressure) but designed for 25,000 psi. Apparently there are at least Type III and Type IV hydrogen storage tanks in use.

Meanwhile, at NWP and ambient temperature, ISO 19881 requires that the steady-state permeability of Type IV hydrogen storage tanks in the system should be less than 6 Ncm3/h/L. (see "Review of the Hydrogen Permeability of the Liner Material of Type IV On-Board Hydrogen Storage Tank".

The density of hydrogen at STP (68 degF 1 atm) is 0.08376 kg/m3. A typical(?) hydrogen vehicle gets 70 miles/kg H2, so a 300 mile range requires a tank capacity of 4.28 kg. A 10,000 psi hydrogen tank will be about 200 liters or 3-4 times the volume of gasoline tanks typically found in ICE cars. So such a tank to meet the ISO standard will lose hydrogen when fully pressurize at:

6 Ncm3/h/L * 200 L * 30 (days/mon) * 24 (hr/day) = 864,000 cm3/month

At a (STP) density of 0.08376 kg/m3 and with 1,000,000 cm3/m3, losses are:

864,000 * 0.08376 / 1,000,000 kg/mo = 0.0724 kg/mo equivalent to 1.3% of a 5.6 kg charge.

The 2mL/min rate of the A and B vehicles above and a 200L tank, equates to about 2 mL/min * 60 /200 = 0.6 Ncm3/h/L or 10x lower than the standard demands, making their tanks lose only 0.13% of a charge per month.

The Toyota Mirai 2022 has a Type IV tank capacity of 5.6 kg H2 spread over three tanks running at a pressure of 70MPa (10,150 psi).

Types of Hydrogen Storage

Pressurized Tanks

The hydrogen storage tanks used for high-pressure gaseous hydrogen storage can be roughly divided into five types:

  • Type I: metallic pressure vessel,
  • Type II: metallic liner hoop wrapped with CFRP
  • Type III: metallic liner fully wrapped with CFRP
  • Type IV: polymer liner fully wrapped with CFRP
  • Type V: has 20% less weight than type IV, is made of composites without a liner

Vehicle tanks are designed to operate at 10,000 psi but rated for 25,000 psi.

Metal Hydride Tanks

Metal hydride storage systems for hydrogen operate at much lower pressures than pure hydrogen tanks. For a discussion of the technology see:

"How Powder Metal Hydrides Solve Safety And Size Challenges For Hydrogen Storage" - GKN Sinter Metals Engineering GmbH - Jan 2020

Some quotes:

"As an alternative to high-pressure storage systems, metal hydrides are a safe and controllable technology to store hydrogen at lower pressures in small spaces. This low-pressure concept works because the hydrogen molecules are chemically bonded within the metal compound structure and remain stable and nonhazardous at atmospheric pressure. Metal hydride storage systems typically operate at 10-40 bars, which is twenty times less than typical high-pressure systems. Once the hydrogen is needed, the desorption process begins by feeding thermal heat (45 – 65°C) so gas begins to flow outward. At this stage, pressures are down to around one to two bars."

High Pressure Hydrogen Pipelines

As an alternative to on site compression of gaseous hydrogen at hydrogen gas stations for fuel-cell vehicles fill-ups, an analysis of the economics of a high pressure hydrogen distribution pipeline shows cost savings over hydrogen delivery trucks. The report "Economic analysis of a high-pressure urban pipeline concept (HyLine) for delivering hydrogen to retail fueling stations" was developed by staff at the National Renewable Energy Laboratory (NREL) and independent contractors. The Green Car Congress site carries the same story.

Hydrogen Safety

An in depth review of the safety of hydrogen was presented at the 2nd Joint Summer School on Hydrogen and Fuel Cell Technologies, on 19 September 2012, Crete:

Hazards related to hydrogen properties and comparison with other fuels - Ulster University - Vladimir Molkov, 2012

a briefer discussion of hydrogen safety is shown at:

Dispelling Common Hydrogen Safety Myths - July 12, 2018

Electrolysis of Sea Water

"A step closer to sustainable energy from seawater" article from phys.org Aug 2018 talks about a catalyst that reduces the amount of chlorine you might get when using seawater in electrolysis. Presumably brine (saltwater) would have the same problem. Properly captured and separated/managed, chlorine has the potential to be used in other products (chemicals such as bleach).

From Wikipedia on Chlorine:

"In industry, elemental chlorine is usually produced by the electrolysis of sodium chloride dissolved in water. This method, the chloralkali process industrialized in 1892, now provides most industrial chlorine gas. Along with chlorine, the method yields hydrogen gas and sodium hydroxide, which is the most valuable product."

From the article "China set to drive global chlorine capacity by 2024"

"The global chlorine capacity is poised to see moderate growth over the next five years, potentially increasing from 87.69 million tons per annum (Mtpa) in 2019 to 92.13 Mtpa in 2024, registering total growth of 5%"

The chlor-alkali process is electrolysis of sodium chloride solutions (e.g. brine) to produce hydrogen, chlorine and sodium hydroxide (the alkali bit). Stoichiometrically, for every molecule of chlorine produced there is one molecule of hydrogen produced. So 87.69 Mtpa of 2019 chlorine (atomic weight 35.45) should produce 87.69/35.45 = 2.47 Mtpa of hydrogen. Does the US really need anymore chlorine?

Worldwide Hydrogen Production

Meanwhile, (from a Nov 2012 article) 2019 total world production of pure hydrogen is 75 million metric tonnes. The same article reports:

"Electrolysis of water at ambient temperatures requires 50-55 kWh per kilogram of hydrogen produced* (hence 60% and potentially 70% efficient with improved catalysts)."

The power to make the world's 75 million tonnes of pure hydrogen via electrolysis is therefore 75,000,000,000 kg * 55 kWh/kg = 4,125,000 GWh.

From Wikipedia,

"As of the end of 2020, the United States had 97,275 megawatts (MW) of installed photovoltaic and concentrated solar power capacity combined."

If all the US installed solar power operated for 2000 hr/yr, it would generate 2000 * 97,275 MWh = 194,550 GWh. That in turn could then make 4.7% of the world's supply of hydrogen, insufficient for US purposes. At $1.8/kg H2, the corresponding annual gross income would be $75,000,000,000 * 0.047 *1.8 = $6.345 billion/yr.

Worldwide Oxygen Production

When electrolyzing water for hydrogen it of course produces pure oxygen at the same time. Wikipedia reports the industrial production of oxygen via a number of processes was 100 Mtpa in 2003. The economic impact of renewable hydrogen and it's cogenerated oxygen very much needs to take this into account.

At $10/kg, the US' 41 Mtpa H2 comes with 41 * 16/2 Mtpa O2 = 328 Mtpa O2 which would on the face of it be worth $3,280 Billion/yr.

Utilizing Byproduct Oxygen

In the report "Effective utilization of by-product oxygen from electrolysis hydrogen production",the researchers at the Nagoya University, Japan, review its economic impact on renewable hydrogen production.

Another study "Oxygen From Electrolysis For Medical Use: An Economically Feasible Route" from Italy shows how medical centers could benefit from cogenerated oxygen from renewable hydrogen electrolyzers.

US Hydrogen Demand

Meanwhile US demand for hydrogen is forecast to quadruple to 41 Mtpa by 2050 meaning it must be about 10 Mtpa now. From the above, US solar power could produce about 3.525 Mtpa H2 (with no solar power going into the grid). If NM could meet that demand, the state could enjoy that gross income of $6.345 billion/yr. For comparison 2016 NM state revenues were $5.462 billion/yr (Ballotpedia). But there are lots of buts: we should back out hydrogen from chlorine production from the calcs, for example

US Hydrogen Electricity Demand

According to Tom Solomon's (350NM) projections, for 100% energy production from renewables the US will need an installed base of 4,545 GW (by 2036) Operating at 2000 hr/yr that's 9,090,000 GWh, To meet the 2050 US demand for hydrogen of 41 Mtpa at 55 kWh/kg H2 then would require:

41,000,000,000 kg * 55 kWh/kg / 1,000,000 kWh/GWh = 2,255,000 GWh.

(Note, by 2050 improved technologies may exceed the 55 kWh/kg H2. 2000 hr/yr is 5.5hr/day 365 days a year. See Unbound Solar)

Based on a 2000 hr/yr operation, this would require increasing the installed renewable energy base by 1,127.5 GW an increase of 24.8% over Tom's 2036 number. At $1.8/kg (current fossil hydrogen prices), 41 Mtpa h2 is worth $73.8 Billion/yr.

Reduced GHG emissions

At 7 kg CO2/kg H2 on average for steam methane reforming (SMR), converting a US demand of 41 Mtpa to renewables saves 41 * 7 = 287 million tonnes/yr of CO2 emissions and an unknown amount of leaked potent methane emissions.

Electrolysis Water Consumption vs 'Produced' Water Generated

A US demand of 41 Mtpa H2 will consume 41 * 18/2 Mtpa water = 369 Mtpa water. The water consumption of fracking in the Permian basin is estimated to generate 32 million barrels of produced water per day in 2025 (SFNM). In a year with say 10% downtime, that's 10.5 billion barrels/yr. With 42 US gals/barrel and a US gallon weighs 8.33 lb that's:

10.5 x 42 x 8.33 billion lb /yr = 3,673 billion lb water/yr

and a metric tonne is 2204.6 lb, so the Permian Basin produced water is 1,666 Mtpa or 4 and half times the water consumption needed for US hydrogen production via electrolysis, if it shuts down all fracking in just the Permian basin!


The World Hydrogen 2022 Summit & Exhibition, the leading global platform dedicated to hydrogen industry advancement is produced by the Sustainable Energy Council (SEC) in partnership with the Province of Zuid-Holland, the City of Rotterdam and the Port of Rotterdam, World Hydrogen 2022 is the place to meet with government and private sector leaders to showcase, discuss, collaborate and do business, driving the hydrogen industry forward.

Special Interest Groups on Hydrogen

The UK Institution of Chemical Engineers, magazine The Chemical Engineer hosts a hydrogen special interest group that examines a wide variety of issues associated with a 'hydrogen economy.

Renewable Hydrogen Opportunities

If New Mexico were to overbuild solar and wind capacity it's possible to estimate how much excess power could be generated, converted to hydrogen and sold to the industrial users. The industrial gasses sector is orders of magnitude bigger than anticipated energy storage and transportation needs. Such a proposition needs to be compared with just selling the power in terms of costs, locations and jobs. Which is quicker and cheaper a) export H2 in trucks or pipelines or b) build transmission lines to export the energy?


Renewable hydrogen (made by electrolyzing water with renewable energy, aka 'green 'hydrogen))

  • is not a problem as far as water usage is concerned,
  • saves water when combined with curtailing fracking as methane demands are replaced,
  • in transportation applications does not have a leakage (permeation) problem,
  • is big business when decarbonizing industrial hydrogen (SMR) production,
  • makes big cuts in GHG emissions; CO2 from SMR and methane emissions,
  • brings additional economic benefits from the utilization of by-product oxygen.

While, the power requirements to meet US industrial hydrogen demand may be only as much a 1/4 of total needs, building out a renewable hydrogen business in NM could go along way to meeting our state budgetary needs, depending on taxation and public ownership issues. Continuing technological improvements in efficiencies and performance in the electrolyzer, fuel-cell and storage fields make this picture improve all around.


bcm = billion cubic metres

CFRP = Carbon fiber reinforced plastic.

EJ = exajoules (1 EJ is about 947.8 trillion BTUs, or 278 thousand GWh)

ICE = Internal Combustion Engines

MPa = megaPascals (1 MPa = 145.04 psi)

psi = pounds per square inch

Ncm3/h/L = Normal cubic centimeters per hour per liter (of storage capacity)