The hydrogen economy is developing as a, still small, part of the low-carbon economy in order to phase out fossil fuels and limit global warming. Theoretically hydrogen, as a molecule instead of electron, has a huge potential to facilitate transport, storage, re-conversion into power, and thus as a fuel and means to stabilize the renewables grid.

On the other hand, in many industrial sectors of the economy dependency on (lately cheap) fossil fuel is hardwired, replacing it with hydrogen may be easier than switching to solar and wind.

what is hydrogen?

Hydrogen molecule H2.

Wikipedia: Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all baryonic mass. Most of the hydrogen on earth exists in molecular forms such as water or organic compounds. Hydrogen gas forms explosive mixtures with air in concentrations from 4–74%. This reaction produces as byproduct water, it releases no CO2 to the atmosphere (decarbonization).

2H2 + O2 → 2H2O + energy

When burnt with air it releases small quantities of nitrogen oxides NO2 and NO3.

how much hydrogen is produced today? 

In 2019 70 million tons of hydrogen was consumed in industrial processing. This hydrogen generation market is valued at 100 billion USD plus a business.

There are four main sources for the commercial production of hydrogen: natural gas (produced by the steam reforming of methane or natural gas), oil, coal, and electrolysis. Only a minor role is being played by the electrolysis of water due to the high electricity input necessary. Biomass and biogas could also serve as primary inputs in H2 production. 

origins/production of hydrogen.

  • grey hydrogen from fossil fuels, 
    steam methane reforming (SMR) of natural gas,
    CH4 + H2O ⇌ CO + 3 H2 (Syngas),
    CO + H2O ⇌ CO2 + H2
    this is currently the cheapest source of hydrogen,
    ~1.5-2 EUR/kg depends on the price of natural gas.
    during the production of 1 ton of hydrogen 5 to 6 tons of CO2 are released as greenhouse gas emissions to the atmosphere.
  • brown, from coal.
  • blue hydrogen, from natural gas via SMR if CO2 is captured, carbon capture, utilization, and storage (CCUS), costs money, may come feasible with incentives,
  • green hydrogen (renewable, from wind/solar and electrolysis of fresh water),
    still 3.5 – 5 EUR/kg coming down with green electricity generation prices declining,
    cost of electrolysis to come down as technology develops, alkaline water electrolysis, proton-exchange membrane (PEM) water electrolysis and high-temperature water electrolysis, etc., economies of scales should be possible with widespread adoption, green H2 mass production requires always large volumes of cheap green electricity (renewables, solar in the desert, nuclear, etc.).
  • hydrogen from carbonization processes,
  • hydrogen as a byproduct of other chemical processes, caustic soda, chlorine, etc. in which case it might be for free.

We are seeing hydrogen use to go from today’s primarily grey production to mainly blue by 2030, and hopefully more green by 2040 and primarily green by 2050.

agricultural use of hydrogen.

  • ammonia production for fertilizer, NH3, Haber–Bosch process, nitrogen fixation,
    N2 + 3H2 → 2NH3
    H2 from grey steam methane reforming (SMR) is the main source,
    blue H2 is more expensive than grey H2, if the price of CO2 emissions increases, this may become viable,
  • production of fertilizer from green ammonia means decarbonizing agriculture,
  • industrially (via SMR) produced ammonia is responsible for 1 percent of global greenhouse gas emissions.

industrial use of hydrogen.

Apart from its use in the production of ammonia and fertilizer, hydrogen has widespread industrial applications

  • oil refining of crude and intermediate oil products into refined fuels, also for removing sulfur, etc.,
  • as a raw material in the chemical industry,
  • for methanol CH3OH, which is used in the manufacture of many polymers,
  • in the production of carbon steels,
  • as a reduction agent in the metallurgic industry,
  • for metal alloying, 
  • for flat glass production,
  • in the electronics industry, etc.

heat use of hydrogen.

Hydrogen could transform the global energy system as a natural substitute for fossil fuels, with its potential major role as a zero-carbon energy carrier, and it is the oil industry itself that is looking to adapt, to remain relevant. Zero-carbon fuel and the greening of production processes is an interesting subject to the 

  • steel industry, the traditional blast furnace method releases large amounts of carbon,
  • cement industry,
  • ceramics,
  • medium grade heat, paper,
  • medium grade heat, plastic production,
  • and many others.

hydrogen in mobility.

The transport sector is in many ways similar to the industrial heat consumers, in that it is difficult to decarbonize, and H2 may be more suited to replace its fossil fuel dependency than solar and wind.

  • fuel cells, cars, and buses, first for large transport and long distances, trains, etc. In general, one kilogram of hydrogen corresponds to around three liters of fuel.
  • pure H2 internal combustion engine seems like an option, but also tricky in transportation.
  • easier and more stable is the use of ammonia, a stable fuel, and already used in shipping today.

Interesting the US study Path to Hydrogen Competitiveness lists several especially long-distance hydrogen transport options as highly competitive with their low-carbon alternatives.

power use of hydrogen.

  • fuel cells, 
  • internal combustion engines,
  • reconversion to power,
  • the potential for decentralization and flexibility by pure H2 CHP, highly efficient when heat is a co-driver.

It needs foremost cheap clean electricity (renewable and nuclear) for this hydrogen to become a significant part of the low-carbon economy, hydrogen can be stored and transported in existing gas pipelines, or new pure H2 pipelines, for any type of reconversion into electricity, thus closing the circuit. 

storage and transport of hydrogen.

  • blend with clean gas (including hydrogen) into the gas grids (8% in past, now 25-40% seems feasible),
  • pure H2 pipeline network, conversion old network (new compressors), new H2 pipeline network,
  • H2 piping is the transportation of power, is lossless compared to electricity (like NG), hydrogen transport cost by pipeline is a great factor cheaper than electricity transport cost by a cable, capacities are many factors higher than electricity,
  • guarantees of origin for blue and green hydrogen is an issue (blockchain),
  • liquified H2, cryogenic, -253 °C, energy-intensive, for trucking, train, ship transport, if well insulated, stays liquid for 2 weeks,
  • pressurized hydrogen gas, compressed to 700 bar, expensive tank (carbon fiber, spheric), and compression, many spheric tanks can be combined on one trailer.

the future? clean electrolysis.

Wind and solar electricity production cannot be controlled as we switch on and off some other power plants, in fact, their timely production can be estimated in advance, but not controlled. 

As more green capacity comes online every day, the more we need to manage these imbalances between production and consumption intelligently (smart grid), stabilize the grid, and smooth out the bumps. 

With at times an abundance of green renewable energy production at a time of the day when excess grid electricity is really cheap, this supply overhang of green electricity is looking for storage, for new demand. 

It may be then that it is economical to produce hydrogen via water electrolysis; that the production of green hydrogen seems like an obvious solution, as hydrogen is in principle transportable and storable (power to H2).

But a lot has to happen politically, and institutionally, the mechanisms have to be created so that the huge investments will be undertaken, and a lot of work will have to be done first.

Current best processes for water electrolysis have an effective electrical efficiency of 70-80%, so that producing 1 kg of hydrogen requires 50–60 kWh of electricity (H2 has a specific energy of 143 MJ/kg or about 40 kWh/kg).

As of 2020 green hydrogen costs between $2.50-6.80 per kilogram and blue hydrogen $1.40-2.40/kg compared with high-carbon grey (dirty) hydrogen at $1–1.80/kg (Wikipedia). 

As of 2022 this amount has doubled, depending on where you live.

In 2020 major hydrogen analysts however predict that green hydrogen could become cost-competitive by 2030 as economies of scale drive down the cost of electrolyzers and the price of wind and solar power continues to fall.

It is the cost of equipment and the cost of supply of hydrogen, that are key cost drivers.

The US study Path to Hydrogen Competitiveness sees production costs of hydrogen to be 60% lower by 2030 and hydrogen delivery costs 70% lower.

Effective implementation of the hydrogen economy will need more: notably a framework of carbon taxes, carbon certificates trading, and carbon incentives of whatever kind. Only then can low-carbon hydrogen play an important role in a low-carbon grid.

With the ambitious goal as set out in the European Hydrogen Strategy to establish the principle of CO2 as the new “currency” of the energy system, the EU moves in the right direction.

how much renewable green energy is needed? 

Producing the vast quantities of green H2 that the world will need would require an absolutely massive amount of renewable energy; this means thousands of GigaWatt of new renewable installations. Interesting numbers for 2050 for Europe and North Africa are published in Dii’s North Africa – Europe Hydrogen Manifest.

hydrogen from biogas.

Instead of electrolysis, however, H2 will be produced using the known steam methane reformation process (SMR). In the process, natural gas reacts with water vapor at high temperatures and pressure, resulting in hydrogen and CO2. Steam reforming currently accounts for about 75 percent of the world’s hydrogen supply, so it’s much more common than electrolysis. Under current conditions (2022/10) this may well be the cheapest way to produce green hydrogen.

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