The green hydrogen economy has been announced with a lot of hype, and we will see what will happen, if it develops, and whether it’ll carve out more than a small part of the low-carbon economy.
In order to phase out fossil fuels and limit global warming, green hydrogen has for some become the new wonder vector, the silver bullet, the Swiss army knife to decarbonize. Is it all just hopium, a mix of hope and opium?
Theoretically hydrogen, as a molecule instead of an electron, has a potential to facilitate transport, storage, re-conversion into power. In practice it is physics and economics that will prevent us from using green hydrogen for much else than for what we use grey & black hydrogen today.
There are some sectors of the economy (e.g. fertilizer), that are in true great need of and will have green hydrogen production applications at scale in the future. These are foremost those sectors that need and use (mainly grey) hydrogen today (fertilizer, some chemicals, steel, petroleum, …).
For many other industrial sectors, transport, shipping, industrial and home heating, electrification with renewable sources will be cheaper, more secure and more sustainable.
Green hydrogen will be produced in those countries (e.g. Morocco) where renewables, wind, and solar are in abundance and cheap. Industry in need of the green hydrogen molecule will move to these countries, and there will be most likely only a little shipping of hydrogen, neither in liquid, nor in compressed form, nor in pipelines, not through fancy chemistry, it seems very complicated at this stage.
what is hydrogen?
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 2022 94 million tons of hydrogen was consumed in industrial processing. This hydrogen generation market is valued over 100 billion USD plus a business.
There are four main sources for the commercial production of hydrogen: natural gas (produced by steam reforming of methane or natural gas), oil, coal, and electrolysis. In fact 6% of the global natural gas is used to produce hydrogen, 2% of global coal, combined 830 MtCO2Eq/year is the GHG emissions impact of the current hydrogen economy, this is 2.3% of global emissions.
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. colors 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/black, from coal.
- blue hydrogen, from natural gas via SMR if CO2 is captured, carbon capture, utilization, and storage (CCUS), costs money. It is hard to think this will become feasible in the next decades.
- green hydrogen is produced from renewable electricity, from wind/solar and electrolysis of fresh water. This is still 3.5 – 5 EUR/kg, but coming down with green electricity generation prices declining. The cost of electrolysis shall be coming down too as global subventions work through and technology develops and scales up, alkaline water electrolysis, proton-exchange membrane (PEM) water electrolysis and high-temperature water electrolysis, etc.,
But green H2 and to only replace the current 94 Mt/year of used grey/black hydrogen require building enormous new generating capacities of green electricity (renewables, solar in the desert, etc.), it requires understanding the new H2 electrolysis technology at scale, it requires financing and addressing the multiple security concerns.
- pink hydrogen, when electricity is of nuclear origin.
- 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 primarily green by 2050. With solar and wind becoming ever cheaper, green hydrogen production will become cheaper and maybe competitive.
agricultural use of hydrogen.
- ammonia feeds the world.
- ammonia production for fertilizer, NH3, Haber–Bosch process, nitrogen fixation,
N2 + 3H2 → 2NH3.
H2 from gray steam methane reforming (SMR) is the main source.
blue H2 is more expensive than gray H2, if the price for pollution allowances (CO2 emission certificates) increases, this may become viable.
- green ammonia from green H2, production of fertilizer from green ammonia means decarbonizing agriculture.
- ammonia production is 130 million tonnes a year; four-fifths of this goes into fertilizers.
- industrially (via SMR+Haber Bosch) produced ammonia is responsible for 1 percent of global greenhouse gas emissions, i.e. 400 million tons of CO2.
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.,
- in the production of carbon steels,
- as a raw material in the chemical industry,
- for methanol CH3OH, which is used in the manufacture of many polymers,
- as a reduction agent in the metallurgic industry, hydrogen is needed to replace the chemical reductant carbon monoxide,
- 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 are interesting subjects to the
- steel industry: for heat as the traditional blast furnace method releases large amounts of carbon, but in many cases has the steel industry already begun to go all-electric, high-temperature arc furnaces for steelmaking are already quite popular, and resistance heating in rolling mills similarly replace ovens, hydrogen remains relevant as a chemical reductant agent.
- cement industry,
- medium-grade heat, paper, better served by electricity,
- medium-grade heat, plastic production, better served by electricity,
- there is a simpler and more efficient electric solution for many applications.
Just as there are theoretical applications for hydrogen in industrial heating, many other electrical and biofuel alternatives are more affordable and secure. In fact, electrical alternatives are being deployed in many places, not so (yet) hydrogen.
Any change in heat generation equipment away from burning fossils is going to be expensive. Existing fuel boilers and natural gas compressors will not work readily for hydrogen.
Changing directly to electrical heat-generating systems will be easier, less costly, and more secure.
hydrogen in mobility.
The transport sector is in many ways similar to the industrial heat consumers, in that it looks as another obvious easy play for H2, it looked for years as if it may be more suited for hydrogen to replace the mobilities’ fossil fuel dependency, but then BEV (battery electric vehicles) took off, and if powered by renewable electricity from solar and wind they win hands down on emissions.
- FCEV (fuel cell electric vehicles), cars, and buses, for large transport and long distances, trains, etc., are above all more complicated the BEVs.
- one kilogram of hydrogen corresponds to around three liters of fuel.
- three liters of diesel remain less than 3 kilograms, at ambient temperatures.
- one kg of hydrogen at ambient temperatures takes up a volume of around 11 m3, which is the quantity needed to drive 100 km in a passenger car.
- such is the low volumetric energy density of hydrogen. The energy density per unit mass is excellent – but not per unit volume. For a 500 km journey, an FCEV will need about 5 kg of hydrogen. At 700 bar a storage system would still have a volume of about 200 liters or 3-4 times the volume of a gas tank. Today it seems FCEV vehicles have completely lost it to BEV.
- 700 bar storage is neither easy, secure, cheap, and it takes a lot of electricity to compress to this pressure.
- pure H2 internal combustion engines too seem like an option but are also tricky in transportation.
- easier and more stable is the use of ammonia, a stable fuel, and already used in shipping today, just ammonia takes up more space than diesel.
Interesting the US study Path to Hydrogen Competitiveness lists several especially long-distance hydrogen transport options as highly competitive with their low-carbon alternatives.
But H2 reality bites. It is easier, cheaper, more efficient, and more secure to use electricity in a BEV.
power use of hydrogen.
- fuel cells.
- internal combustion engines.
- we are taking in both cases of reconversion to power.
- H2 harbors the potential for decentralization and flexibility, maybe through a pure H2 CHP, when heat is a co-driver…
This roundtrip, electricity-hydrogen-electricity costs some 70-80% of electricity.
It needs foremost cheap clean electricity (use of renewable’s overcapacity) for this hydrogen re-powering, any power-to-X, to become a significant part of the low-carbon economy.
Hydrogen can then theoretically be stored and transported for reconversion into electricity, thus closing the circuit again. This may be an option for off-grid, far away, remote applications, but in an easier way you can deliver the same with biofuels, this is the competition.
storage and transport of hydrogen.
- blend with natural gas (including hydrogen) into the gas grids (8% in past, now 25-40% seems feasible), the problem is the much higher volume that needs processing, the more we add hydrogen the less there is energy content per volume.
- pure H2 pipeline network, conversion of old networks (new compressors), new H2 pipeline networks, seems all expensive, needs another driver.
- H2 piping is the transportation of power, as a seemingly lossless carrier when compared to electricity (like NG), hydrogen transport by pipeline has many technology hurdles to overcome, the future will tell.
- guarantees of origin for blue and green hydrogen is an issue (maybe blockchain, or maybe this is hype,…),
- liquified H2, cryogenic, -253 °C, energy-intensive, for trucking, train, ship transport, if well insulated H2 stays liquid for 2 weeks, blow-off 1% per day.
- pressurized hydrogen gas, compressed to 700 bar, expensive tank (carbon fiber, spheric), and compression, many spheric tanks can be combined on one trailer.
Direct storage of electricity in lithium-ion or Li-ion batteries is the competition. These batteries are widely applied already and seem practical.
A different kind of storage that is well known is pumped hydro energy storage, it can be readily scaled to any required storage capacity at a known and affordable cost. For hundred years this technology has been applied with a lot of success.
Hydrogen is in competition with electrify everything. Competition is what will define whether hydrogen as envisioned by some will take off.
the future? clean electrolysis.
Wind and solar electricity production cannot be controlled in the same way 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 intelligently these imbalances between production and consumption, stabilize the grid, and smooth out the bumps (smart grid).
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, or 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 new technology will have to be made to work first.
Electrolysers reportedly don’t like being turned on and off.
hydrogen from biogas.
Instead of electrolysis, H2 is 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 already well understood. Under current conditions (2022/10) this may well be the cheapest way to produce green hydrogen.
so what is this hopium?
As described here: Hopium is a merging of the words “hope” and “opium”. When used, it means the conversion of hope into a drug that compromises our ability to analyze and make good judgments about new technology.
More on hopium: