Sustainable and fossil hydrogen in all colours of the rainbow

Hydrogen does not come out of the ground as natural gas or oil. Nor does it grow as biomass on a tree. If you want to use hydrogen, you must make hydrogen. This can be done sustainably and in many ways.

Hydrogen is a crucial raw material and energy carrier. Hydrogen has always been that, but in the light of climate policy, its importance is increasing sharply. It is important that we produce a lot of hydrogen without CO2 emissions.

Anyone who is more familiar with hydrogen knows the hydrogen colours grey, blue, and green. The stripes on the zebra crossing symbolize diversity. In this case, the diversity of options for producing hydrogen. This article introduces this diversity, a consideration of the potential of various options and a guess as to which option will be relevant for climate policy over time.

Hydrogen made from fossil fuels or biomass?

The first is the production of hydrogen from common energy carriers, such as natural gas, oil, or wood. The energy required for this process comes from the starting material, which decomposes into hydrogen and residual products through a chemical reaction.

Grey hydrogen - Steam methane reforming or partial oxidation

In a reaction of natural gas with steam, hydrogen and CO2 are formed at high temperatures (700 – 1100 °C). The CO2 is immediately separated and vented to the atmosphere. About 75% of the original energy in the natural gas is retained due to the loss of heat and the separation process of hydrogen and CO2. Just like natural gas, oil, coal, and lignite can also be processed into hydrogen using steam or oxygen. Because the ratio of hydrogen and carbon in coal and oil is less favorable than in natural gas, much more CO2 is released (for the same amount of hydrogen).?

Potential: Manufacturers of fertilizers, petrol, plastics, glass, metals, and margarine all over the world are major consumers of hydrogen. Today, they are practically all dependent on steam methane reforming.

Timeline: The production of grey hydrogen is huge these days and must go to zero to slow down climate change.

Brown hydrogen - Hydrogen from biomass or biogas?

In addition to fossil fuels such as natural gas and coal, biogas and wood pellets are also suitable for producing hydrogen. If this production does not go faster than the biomass can grow, brown hydrogen is CO2 neutral.

Potential: This form of hydrogen has all the disadvantages associated with other biomass applications. Availability of sustainable biomass thus limits the potential of brown hydrogen.

Timeline: Purified biogas (green gas) has the same composition as natural gas and can therefore be fed directly into the grey hydrogen plants. Brown hydrogen is therefore the fastest source of CO2-neutral hydrogen. With guarantees of origin for biogas, this can already be done tomorrow.

Blue hydrogen - Grey hydrogen with CO2 storage

Just like grey hydrogen, blue hydrogen is made from natural gas, coal, or petroleum. At the point in production where producers of grey hydrogen blow the separated CO2 into the air, the producer of blue hydrogen transports the CO2 to a storage facility, for example an empty gas field.

Potential: All producers of grey hydrogen already separate the CO2. This concentrated flow of CO2 is well suited for storage, especially if the transport distance between the hydrogen plant and the storage facility is not too great. This is therefore a point of attention for new hydrogen plants. Also, every empty gas field eventually fills up again. CO2 storage cannot continue indefinitely.

Timeline: CO2 capture and storage is technically sufficiently mature and applicable at many existing hydrogen plants. If governments come along with support this year, the first blue hydrogen projects will probably be operational around 2025. However, this only concerns the conversion of existing factories, which therefore only meet existing demand. New construction of additional hydrogen plants will probably take a little more time, even though CO2 storage is included from the design phase.

Silver-blue hydrogen - methane cracking?

CO2 is released during the production of hydrogen from natural gas and steam. It is also possible to 'crack' natural gas or biogas (methane, CH4) directly into hydrogen and solid carbon. This solid carbon is much easier to transport and store than gaseous CO2. The solid carbon can also be sold as graphite. Russia seems to be committed to this form of hydrogen production.

Potential: Roughly the same as the potential for grey hydrogen.

Timeline: Proven on a pilot scale, but it remains to be seen what problems manufacturers will encounter in scaling up and making this process competitive. Do not expect large-scale adoption before 2030.?

Golden hydrogen - Renewable hydrogen with CO2 storage?

CO2 storage (blue hydrogen) makes grey hydrogen CO2 neutral. Hydrogen made from sustainable biomass is CO2 neutral. CO2 storage (or cracking) makes the production of hydrogen from biomass CO2 positive.

Potential: Based on cracking, the same as the potential for brown hydrogen. Based on CO2 storage, the availability of empty gas fields counts as an additional limiting factor.

Timeline: If governments provide support this year, the first blue and therefore also the first gold hydrogen projects will probably be operational around 2025.

Hydrogen made from water using electricity

The second is water as the raw material. By running electricity through this water (electrolysis), the water breaks down into hydrogen and oxygen. During the production itself, therefore, no CO2 is released, but harmless oxygen.

Bright green hydrogen - electrolysis with renewable electricity surpluses?

Green hydrogen from surpluses seems to be the hope in anxious days for the energy transition. Surplus electricity from windmills and solar panels can be stored in the form of hydrogen for times when the wind is not blowing and when it is dark.

Potential: Nil. Hydrogen production from surpluses is a nice dream in theory, but an economic nightmare in practice. I'll explain why later.

Timeline: On a small scale, hydrogen production from surpluses is possible quickly. The technology is there and so is the subsidy if we are not paying attention. However, it will never scale.

Green hydrogen - electrolysis with renewable electricity

Even when electrolysers do not run on surplus green electricity, the hydrogen is called green. Rightly so, no CO2 was released. In addition to the variable power from wind turbines and solar panels, hydropower, geothermal energy, and solar power stations are also successful in making green hydrogen. We do not know these last sources in every country, but hydrogen can be easily transported by pipe or ship.

Potential: Infinite. There is no shortage of sustainable energy, nor of materials to convert energy into hydrogen.

Timeline: For the time being, there is practically no country that structurally produces more sustainable electricity than it consumes. Most major electricity markets still run for at least half on coal and gas. In the coming decades, new wind farms, solar farms or hydroelectric power stations will therefore achieve more CO2 reduction by supplying their electricity-to-electricity consumers than to a hydrogen factory. Before 2035, do not expect production of green hydrogen on a scale anywhere close to the current production of grey hydrogen.

Orange hydrogen - electrolysis with renewable electricity in own country

When it comes to sustainability, the desire to be self-sufficient often also plays a role. The orange label distinguishes between green hydrogen produced domestically and imported hydrogen.

Potential: Limited. Only offshore wind farms are suitable for hydrogen production in terms of production factor. To make the current (grey) hydrogen consumption of the industry greener, more offshore wind capacity is needed than is planned for 2030. Even more capacity is needed for all new plans with hydrogen. Many countries are very energy intensive and compact. Being self-sufficient through large-scale use of hydrogen is not a realistic goal for many countries – even given an infinite budget and time.

Timeline: All wind turbines and solar parks planned in the Climate Agreement are urgently needed to remove the CO2 emissions from coal-fired power stations and gas turbines from the market. Also, because electricity consumption is likely to continue to rise, do not expect 'Orange hydrogen' on any relevant scale before 2035.

Purple hydrogen - electrolysis with nuclear energy?

In addition to wind, sun, hydropower and geothermal energy, nuclear energy is also a source of CO2-neutral electricity. Nuclear energy is great for the climate. This also applies to hydrogen from nuclear energy. There will undoubtedly be readers who nevertheless do not think nuclear energy is such a good idea. Therefore, a different colour.

Potential: Big. Due to their stable supply, nuclear power plants are much more suitable to produce hydrogen than variable wind and solar power.

Timeline: Just like other sources without CO2 emissions, we urgently need existing and newly built nuclear power stations to generate electricity ourselves. Building additional nuclear power stations easily takes 10 to 15 years. Do not expect large-scale hydrogen production from new nuclear power plants before 2035. It should be noted that existing nuclear power stations are currently struggling in many electricity markets. Rescue efforts with a specific hydrogen production order would slightly accelerate the production of purple hydrogen, albeit on a limited scale.

Pitch black hydrogen - electrolysis with gas turbines or coal power?

The call for produced hydrogen is great. There is a good chance that gigawatts of electrolysers are more likely to be installed than wind farms are running to provide these hydrogen factories with energy. Hydrogen production on fossil fuel is then lurking. The system efficiencies are dramatic, and the CO2 emissions are many times greater than those of grey hydrogen from steam reformers.

Potential: Terrifying. Making hydrogen with coal power is completely idiotic from a climate point of view.

Timeline: It is not inconceivable that the hydrogen economy will initially run on pitch-black hydrogen.

Other routes for hydrogen production?

In addition to chemical conversion of fuels and electrolysis, these production methods are also worth considering.

Red hydrogen - thermolysis of water?

Above 2,500°C, water automatically splits into hydrogen and oxygen. With the help of catalysts or via thermochemistry, this temperature can be lowered to below 1,000°C. This makes thermolysis with concentrated solar power or in a nuclear reactor immediately possible.

Potential: Great, on the same order as electrolysis.

Timeline: It is difficult to estimate whether this route has an economic chance against electrolysis.

Pink hydrogen - steam electrolysis?

The thermally and electrically driven splitting of water reinforce each other. At high temperatures, less electricity is needed to produce hydrogen. This makes the combination of nuclear energy and hydrogen production particularly interesting, as roughly half of the energy of a nuclear power plant is normally lost as residual heat. Solar heat, geothermal energy, and other heat sources in combination with electrolysis are also very successful.

Potential: Big. However, the factory must remain at the right temperature. Coupling with wind and sun is therefore not an obvious choice.

Timeline: High temperature and steam electrolysis are slightly behind low temperature electrolysis in development.

Turquoise hydrogen - solar fuels?

Instead of connecting a solar panel and an electrolyser, it is also possible to produce hydrogen directly from sunlight using a photoactive catalyst. In the Netherlands, Differ is working on this, among others.

Potential: Difficult to estimate.

Timeline: A promise for years, but the development backlog of separate electricity generation and electrolysis is large and growing.

Toxic green hydrogen - biochemical hydrogen production

There are algae, bacteria and enzymes that produce hydrogen, for example based on waste heat or sunlight. With the help of selection or genetic modification, the yield of these organisms can be increased.?

Potential: Difficult to estimate.

Timeline: At least nothing on a large scale in the medium term.

Light grey hydrogen - hydrogen as a residual product?

For example, during the production of chlorine gas from table salt and water, hydrogen is released as a by-product. Hydrogen is also a residual product in the production of steel from coal and iron ore and in various chemical processes. Production of this residual flow has CO2 emissions, but those emissions are also there if we do not use the hydrogen.

Potential: Limited. The market for hydrogen is orders of magnitude larger than the hydrogen that is released as residual flow.

Timeline: These residual flows are available. However, capture and purification does not automatically make economic sense.

Coloured bars in a sea of grey?

Sustainable hydrogen is central to the debate on climate and energy. There are countless options for producing hydrogen, but we also need to recognize where we are now. There is hardly any CO2-free hydrogen. So, we must walk all the routes. The zebra crossing above is therefore not only a symbol of a beautiful diversity of options. The stripes also show the relationship between the current production of sustainable and fossil hydrogen. A little colour in a sea of grey.

The cost of hydrogen production is almost irrelevant

First, it is important to reverse this relationship. Grey hydrogen must be removed from the market. As quickly as possible. All hydrogen that is already being used today must be sustainable as soon as possible. It is my estimate that only that will last until at least 2035 worldwide.

Only in roughly 15 years will we then be able to produce 'extra' sustainable hydrogen, for markets that do not yet consume any hydrogen today. And even then, it won't be fast. This requires new steam reformers with CO2 storage, or nuclear power stations, wind farms or reservoirs and electrolysers. Each one of them is a huge project that takes an enormous amount of time.

Sustainable hydrogen for people in a hurry

The fastest route to producing serious volumes of sustainable hydrogen today is neither CO2 storage nor electrolysis of surpluses. Anyone who wants to prove today that he is helping the climate with hydrogen must buy green gas certificates. In a volume equal to its hydrogen consumption, plus the energy loss in a grey hydrogen plant. Anyone who opts for electrolysis hydrogen and considers the climate of paramount importance must switch off the electrolyser if there are no storms. Continuous greening of electrolysis with green energy certificates results in pitch-black hydrogen in practice. So, don't.

Count on an OPEC for hydrogen?

For those who can muster up to 15 years of patience, the next setback is ready. Do not count yourself rich with a low-cost price for electricity and/or electrolysis. Even if the cost price of hydrogen production would plummet in the long term, for example because France is fully committed to hydrogen from nuclear energy, Saudi Arabia on solar power or Russia on blue hydrogen. Even if some countries produce more hydrogen than they can consume themselves.

All hydrogen that companies or countries can do without goes onto the global market. Scarcity is a certainty on that world market. The market price will soon be decisive for hydrogen, just as it is now for oil. There is also a good chance that an Organization of Hydrogen Exporting Countries will step up to influence the market price in its favour, as OPEC is doing now. A low production price is great for the producer but means virtually nothing for the hydrogen consumer.