Ten things you need to know about hydrogen

Lennart van der Burg, expert and business developer for Hydrogen at TNO answers ten pressing questions about hydrogen.

1. What is hydrogen?

Hydrogen is the most common element in our universe. Under normal circumstances it is gaseous and we speak of hydrogen gas (H2). Hydrogen is also the lightest gas we know, but under high pressure it does have a high energy density of 120 megajoules (MJ) per kg. That is almost three times as much as natural gas (45 MJ per kg). Pressurising (compressing) hydrogen gas, however, also requires the necessary energy (about 10%).

2. What is grey and blue hydrogen hydrogen?

Almost all of the hydrogen currently produced worldwide is so-called 'grey hydrogen'. Production currently takes place via Steam Methane Reforming (SMR). Here high pressure steam (H2O) reacts with natural gas (CH4) resulting in hydrogen (H2) and the greenhouse gas CO2. In the Netherlands, approximately 0.8 million tonnes of H2 are produced in this way, using four billion cubic metres of natural gas and generating CO2 emissions of 12.5 million tonnes.

The term 'blue hydrogen' or 'low carbon hydrogen' is used when the CO2 released in the process of grey hydrogen production is largely (80-90%) captured and stored. This is also called CCS: Carbon Capture & Storage. This could happen in empty gas fields under the North Sea. Nowhere else in the world is blue hydrogen produced on a large scale.

3. What is green hydrogen?

Green hydrogen, also known as 'renewable hydrogen', is hydrogen that is produced with sustainable energy. The best known is electrolysis, in which water (H2O) is split into hydrogen (H2) and oxygen (O2) via green electricity. A large number of parties in the Netherlands are experimenting with these megawatt-scale electrolysers. Hydrogen is also released during high-temperature gasification of biomass.

4. What is turquoise hydrogen?

Hydrogen produced from natural gas using the so-called molten metal pyrolysis technology is called 'turquoise hydrogen' or 'low carbon hydrogen'. Natural gas is passed through a molten metal that releases hydrogen gas as well as solid carbon. The latter can find a useful application in, for example, car tyres. This technology is still in the laboratory phase and it will take at least ten years for the first pilot plant to be realised.

5. What are the further fundamental differences between blue and green?

In addition to the method of production, there are a number of other key differences:

• Only green hydrogen produced via electrolysis ensures that large quantities of sustainable electricity produced at sea and on land can be properly integrated into our energy system. Only electrolysis can convert electricity to hydrogen flexibly (on demand) and then store it.
• In addition, the development of large-scale electrolysis will help cater to the rising demand for electricity and thus stimulate the growth of sustainable energy.
• There is also a difference in quality. Green hydrogen has a higher degree of purity and can be used immediately, for example in the fuel cell of a vehicle. Blue hydrogen has a lower purity level, sufficient for industrial application.
• The production of blue hydrogen is a way to 'decarbonise' industry, i.e. reduce CO2, on a large scale and at relatively low cost.

6. What role does hydrogen play in the energy transition?

In our current energy mix, approximately 20% is supplied in the form of electricity and 80% in the form of natural gas or liquid fossil fuel (petrol, diesel). Our climate targets are going to change this situation considerably in the near future. The share of electricity generated by wind and solar power will increase sharply. For a number of applications such as heavy transport, high-temperature processes in industry and aviation, a good electrical solution is still lacking and there is still a need for a sustainable gas. Hydrogen can play a useful role here. In addition, hydrogen is important in the form of large-scale storage for those moments when it is windless and cloudy.

7. Which countries are also working on hydrogen?

Countries such as Norway, Australia, Morocco, Chile, Saudi Arabia, China and Japan are very active with green hydrogen, mainly because there is considerable (potential) availability of cheap renewable energy from wind, solar or hydropower to produce green hydrogen. An exception to this though is Japan, which is largely dependent on imports for its energy supply and has developed a strategy to import (green) hydrogen on a large scale. Its key role lies in technology development. The Netherlands is in a good position thanks in part to our knowledge of gas and electrolysis technology, the great potential for wind energy in the North Sea and the energy-intensive industry that needs to make a strong commitment to sustainability.

8. What are we going to use hydrogen for?

Hydrogen is particularly important for the process industry. It is now mainly used for the production of fertiliser but in the future it can also be used for high-temperature processes such as steel production for which natural gas or coal is now used. In addition, hydrogen will play a role in mobility, for example for intercity buses that have to cover longer distances and where electric driving is not a solution.

9. What does hydrogen mean for the citizen?

In the short term not much will be evident. The use of hydrogen in homes, for example, will be long overdue if this happens at all. For the majority of homes, a collective heat grid or an electric heat pump offers a better solution. In traffic, the number of hydrogen cars (currently less than a hundred) and the number of hydrogen filling stations (in 2018: 3) will slowly increase.

10. What are the risks?

Hydrogen is a very light gas, highly flammable and is used in mobility under pressures up to 700 bar. Just like any other gas, it is important to handle it with care during production, transport and use, and to leave it exclusively to professional companies. If hydrogen is to be used in existing gas pipelines, it is important to further investigate how hydrogen actually 'behaves' in practice. Hydrogen is lighter than natural gas and can escape more easily from valves and seals.