Hydrogen, with atomic number one, is at the head of the periodic table of elements. Chemist Roger Alberto also puts it in pole position in terms of clean energy. For him, it’s clear that we have to abandon the path of fossil fuels. “On the one hand because natural gas, oil and coal are responsible for climate change; on the other because these fuels won’t be available forever.” Hydrogen, by contrast, is in inexhaustible supply as a component of water.
Hydrogen has much going for it. It’s an excellent vehicle for storing energy, as well as being environmentally compatible and highly versatile. A gas at room temperature, hydrogen can be used to make electricity, natural gas and liquid fuels. It’s also a source of fertilizer for agriculture: Around half of the 550 billion cubic meters of hydrogen produced globally every year is used to make plant nutrients.
Car manufacturers the world over are already dreaming of tomorrow’s hydrogen society. They’re trying to harness the properties of hydrogen, and are working on the sustainable vehicles of the future. Their efforts revolve around fuel cells, which convert hydrogen into electrical energy. Unlike internal combustion engines, which pump out CO2, the only exhaust fuel cells produce is water vapor. Recently, the Canton of Zurich put its first two hydrogen vehicles into service, and in the next few years supermarket chain Coop intends to build a fleet of hydrogen-powered trucks.
Hydrogen has what it takes to bring us forward and cover our energy needs in a sustainable and eco-friendly way in the future. There is a hitch, however: At the moment, the way this potent gas is produced is anything but clean and climate-neutral. Ninety-six percent of the hydrogen currently used globally is manufactured from coal, oil or natural gas. Millions of tonnes of carbon dioxide are released into the atmosphere in the process. For this reason hydrogen, in itself a clean fuel, is currently making little or no contribution to climate protection.
If hydrogen is to become a source of clean energy, it will also have to be produced sustainably without CO2 emissions. “It has to be produced carbon-free,” says Roger Alberto. This is possible, for example, using electrolysis, a process where water is split into oxygen and hydrogen with the help of electricity. Around four percent of the world’s hydrogen production is manufactured this way. The problem is that it’s not much use as long as the electricity used in electrolysis is not from sustainable sources such as hydropower, solar panels or wind farms.
Roger Alberto, and with him a consortium of chemists and physicists at UZH and Empa (the Swiss Federal Laboratories for Materials Science and Technology), are pursuing another strategy as part of the LightChEC University Research Priority Program. They want to use artificial photosynthesis to split water and generate hydrogen. “The idea is to convert sunlight directly into chemical energy,” explains Alberto. The process for manufacturing hydrogen by artificial photosynthesis already works in the lab, if only for short periods. The great challenge for the scientists – or the “sore point”, as Alberto puts it – is to develop catalysts that are long-lasting and efficient. Catalysts are used to accelerate reactions. They’re key to artificial photosynthesis because they’re what gets the reduction-oxidation process of splitting the water into oxygen and hydrogen going in the first place.
Catalysts destroyed by UV
The catalysts developed so far by the researchers at UZH have enabled artificial photosynthesis for no more than two weeks before they break down and have to be replaced. That’s still far too short a time. “In reality, catalysts would have to work for years in sunshine, but the UV radiation in the sunlight destroys them,” says Alberto. The researchers are still a long way from solving the problem. The ideal solution would be catalysts that renew themselves. But, as Alberto explains with laugh, nature has spent three billion years working on the catalyst question and hasn’t made much headway, since in natural photosynthesis the catalyst that oxidizes oxygen is replaced every half hour.
It’s still not clear whether artificial photosynthesis will be used to make hydrogen on a large scale in the future. “But a sustainable society that relies completely on hydrogen is conceivable,” Alberto believes. He’s also convinced that the clean hydrogen of the future won’t come from a single source, but will be made using a variety of processes.
We’re not there yet. But, as Alberto says, the transformation of the energy system has to be in sight. There will be no way around alternative energies in the future. He believes that if business, policy-makers and science work together, as was the case more than 50 years ago for the Apollo project, the hydrogen society could become a reality by 2040. Back in the 1960s, concerted efforts and a shared vision enabled the USA to put the first man on the moon within 10 years.
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