First, the most important question: Do we need hydrogen for the energy transition and to meet Switzerland’s goal of becoming net climate neutral by 2050?
Thomas Justus Schmidt: Yes, all our calculations and computer models clearly show that we need hydrogen (H2) in order to achieve this goal. This is also consistent with all other scientific assessments. Hydrogen is the central element of the energy transition. It has a wide range of applications, including energy storage, electricity generation, heating, manufacturing chemicals and producing fuels for transport or aviation. It can be used flexibly, and most of the technologies for producing, handling and using it are mature. Best of all, green hydrogen, produced by electrolysis using electricity from renewable sources, will allow us finally to get rid of the “C” – the carbon – and with it the carbon dioxide (CO2) that is largely responsible for climate change.
What part does PSI play in researching hydrogen technologies?
Research into hydrogen technologies at PSI is as old as PSI itself, that is 35 years. It all started with fuel cells, in other words producing electricity from hydrogen. For about ten years, we have been working on electrolysis, that is producing green hydrogen from water using electricity from renewable sources. A third line of research is power-to-X, where hydrogen is used to produce synthetic methane, diesel or jet fuel, for example. I have been working at PSI since 2011, and in the Energy and Environment research division we not only look at very practical processes in the energy system, but we are actually interested in modelling the entire energy system.
What does that mean?
We develop future scenarios. In other words, we reveal possible paths along which the energy system may develop, and calculate what impact they will have. However, we do not predict the future, as some people believe, but only identify potential pathways. These always depend on a highly complex overall constellation.
Assessing the past is easier. One gets the impression that the perception of hydrogen in the scientific community and the general public has gone through several cycles. At times it was seen as the solution to everything, then again it sank into oblivion.
That impression is correct. The term hydrogen economy already appeared in the early 1970s, in response to the oil crisis. And in the 1990s, some car manufacturers made grandiose announcements, predicting that there would be millions of hydrogen-fuelled cars on the roads by the early 2000s.
Nothing came of that. Why not?
Car manufacturers underestimated the challenges, especially the durability of the fuel cell. They thought it was just an engineering problem. In fact, what was often lacking was a fundamental understanding of what goes on in chemical and physical terms inside the materials that make up a fuel cell. In the meantime, this understanding has improved enormously. So the increase in attention currently being paid to hydrogen is entirely justified.
Prejudices against hydrogen do still exist, though. Let us dispel some of them. We’ll start with the Hindenburg disaster, in which the hydrogen-filled German airship went up in flames in 1937.
I had hoped I wouldn’t need to answer that question any more. But since it keeps getting asked: These days, handling hydrogen is as safe as handling petrol or natural gas. It’s the other way round: if you had to introduce petrol today as new fuel, approval would most likely be difficult because of its flammability and health risks.
Losses due to the diffusion of hydrogen from gas cylinders.
That used to be the case with metal pressure vessels. But nowadays these tanks, especially the hydrogen tanks used in vehicles, are made of carbon fibre composites, in which the problem of diffusion has been solved.
Natural gas grids are not designed for hydrogen, nor are existing heating systems or gas turbines.
In the former East Germany, heating was provided in the form of town gas, which contained up to 50 percent hydrogen. Instead of shutting down natural gas networks, they could be converted to hydrogen. From 2025, Siemens and General Electric intend to produce gas turbines for power plants that will run exclusively on hydrogen.
Green hydrogen is far too expensive.
At the moment, this is still true – but only if the costs are calculated locally and sub-systemically. When all costs are taken into account – especially the environmental and climate damage caused by fossil fuels – the picture is very different. I admit that hydrogen is not the cheapest energy carrier in all situations. You can see this particularly in cars. A considerable proportion of these will certainly be battery-powered.
And the final preconception: Green hydrogen is not in fact carbon-neutral.
That’s true. Electrolysers and fuel cells require precious metals, for example, and mining these often produces carbon dioxide. Moreover, this mining usually takes place in countries where our working conditions and ethical standards do not apply. This is why PSI is researching electrolysers and fuel cells that require fewer precious metals. There has been a great deal of progress in this area in recent years and I think realistically we will eventually be able to manage without precious metals altogether.
If the benefits are that great, what is the snag in the hydrogen economy?
It isn’t the technology. Society now ought to make the decision to adopt hydrogen. This will require infrastructure such as electrolysers, pipelines and storage facilities.
So far we have only talked about hydrogen. But if you want to turn it into methane, petrol or plastics – the “X” – you also need carbon. Where is that supposed to come from?
Ideally, of course, from carbon dioxide in the air. The technology exists, but it’s very expensive. So it makes sense to extract the carbon dioxide from other industrial processes in which it cannot be avoided – such as waste incineration or cement production. Hydrogen should therefore preferably be produced in the vicinity of such plants and then converted into products such as methane or other so-called platform chemicals, such as methanol. These starting materials are essential to the chemical industry, for example for producing synthetic polymers and hydrocarbons. They could replace fossil methane, i.e. natural gas.
How much hydrogen will Switzerland need in order to achieve its net-zero target by 2050?
Our Swiss Times Energy Model – the world's most comprehensive mathematical model of its kind – suggests that 7 to 10 percent of Switzerland’s total energy needs would have to be met by hydrogen. This corresponds to about 12 terawatt hours per year.
And are you confident that Switzerland will choose this path?
I am sure of it. The cost of producing green hydrogen is currently falling. In addition, many countries in Europe have adopted hydrogen strategies, which establish a sound framework – above all Germany with its new national hydrogen strategy. Switzerland can benefit from this and ought pursue the same path.
The Colours of Hydrogen
No, hydrogen (symbol H2) is in fact colourless – the lightest gas of all is invisible to the eye. Instead, scientists use colours to indicate how the hydrogen is produced.
Green hydrogen: The most sought-after form. Hydrogen is split off from water by electrolysis, which also produces oxygen. If the electricity is generated using wind and solar power, no carbon dioxide is produced.
Yellow hydrogen: Also produced by electrolysis, but using electricity from the current electricity mix, which includes fossil fuels, and therefore not carbon neutral.
Grey hydrogen: The most common variety worldwide, but unfortunately also the dirtiest. Produced by steam reforming natural gas or coal, which releases carbon dioxide – ten tonnes for every tonne of hydrogen.
Blue hydrogen: Grey hydrogen plus. Obtained by steam-reducing natural gas, which produces carbon dioxide; however, this is used for other purposes or stored underground.
Turquoise hydrogen: Fossil, but climate neutral. Made from natural gas through the pyrolysis of methane in the absence of oxygen. This produces solid carbon, which is stored underground or processed into various materials.
White hydrogen: Naturally occurring hydrogen is rare but is found in some parts of the world, such as Africa. It is extracted by fracking.
Pink hydrogen: Obtained by the electrolysis of water, using electricity generated by nuclear power. Nuclear power plants do not produce carbon dioxide, but they do produce radioactive waste.