Green hydrogen, the coveted piece that closes the clean energy cycle23/09/2020
Electrolysis makes it possible to produce hydrogen from water without generating emissions. The alternative to store this energy is fuel cells. Credit: Ministerio de Energía - Gobierno de Chile.
FRANCESCO RODELLA | Tungsteno
A power plant that stores clean electrical energy until it needs to be returned to the grid. A factory that generates electricity from the sun and uses this natural resource to make fertilizers with less pollution. Cars with a range of more than 600 kilometres and refuelling times of only five minutes that emit no CO2. There are an increasing number of projects in which renewable hydrogen is the protagonist, and many of them are already a reality. In fact, the promotion of this type of initiative is even at the heart of government initiatives such as the one proposed by Spain over the next decade. But how did we get here?
The use of hydrogen is not new. "It is used massively in industry to refine gasoline, to produce ammonia and methanol, in the manufacture of steel, glass, semiconductors, the food industry and pharmaceuticals," explains Javier Brey, president of the Spanish Hydrogen Association (AEH2) and an entrepreneur and teacher specialising in this sector. For decades, the most common and almost the only way used to obtain this chemical element has been by means of reforming processes, consisting of "breaking up a hydrocarbon molecule such as natural gas, keeping the hydrogen and dumping the CO2 into the atmosphere," Brey adds. But we are faced with the same old problem: harmful emissions are generated.
The green solution was too expensive
There is, however, a clean alternative: obtaining hydrogen through the process of electrolysis. This method makes it possible to produce hydrogen and oxygen from water and electricity, using devices called electrolysers. If this electricity comes from renewable sources, the entire production cycle will be completed without emitting any CO2, according to María Escudero, a researcher at the University of Copenhagen. In this way we can obtain renewable/green hydrogen.
Beyond reducing emissions, this process makes it possible to solve the problem of the "intermittence" of renewables, as is the case with solar or wind energy, since in this way excess electricity can be stored in the form of hydrogen until we need to reconvert it into energy during periods of shortage. One way of obtaining the energy is through a process that is the opposite of electrolysis, using devices called fuel cells. This is an ideal mechanism for sectors that need to reduce their environmental impact, such as transport. And it is a solution that is already real today.
If hydrogen can be the protagonist of a virtuous cycle that opens with a raw material like water and closes with the generation of energy without emitting anything but steam, why has it not played a more important role until now? Jesús Martín, an engineer at the National Hydrogen Centre, and the other experts consulted, all agree that the great obstacle until recently has been the price of renewable energy, which is too high for it to be advantageous to abandon hydrocarbons.
The latest strategies leading the way to decarbonization by 2050 have their focus on 100% non-polluting renewable energy from green hydrogen. Credit: Douglas Frabetti.
The need to decarbonise everything
"In recent years, these costs have fallen exponentially, while the performance of electrolysers and fuel cells have greatly improved," explain Escudero, Martín and Brey. In addition, the global need to decarbonise all sectors has become increasingly clear, as the president of the AEH2 points out. To use the metaphor, it is as if the planets have almost aligned so that hydrogen can take on a leading role in our future. "There is no longer any excuse," says the Denmark-based researcher.
In this context, we must also add the decisions of political leaders in different parts of the world in line with this vision. The European Commission, for example, presented in early July a strategy with time-bound targets for the widespread use of hydrogen by 2050. A few weeks later, the Spanish government followed suit with a national plan that sets out objectives such as at least 25% of the hydrogen used in industry being renewable; as well as having at least 100 hydrogen generators, 150 buses, 5,000 light and heavy vehicles and up to two commercial hydrogen train lines in operation within a time frame of ten years.
Roadmaps of this kind set global decarbonisation targets, involving multiple sectors, says Brey. In Escudero's opinion, this is the only way to achieve the goals set by nearly 200 countries in 2015, through the Paris Agreement to curb global warming. "It is urgent to decarbonise transport, electricity generation and the chemical industry, and this can only be done with renewable energy and green hydrogen," Escudero says. For Jesús Martín, the change in the technological and energy model will come about little by little, and mobility will be the sector in which we citizens will be able to touch the increasingly common presence of hydrogen.
Promoted by the European Union, the Hyflexpower facility will carry out the production and storage of green hydrogen from renewable electricity for Credit: Siemens.
Meanwhile, research groups such as the one led by Escudero in Denmark are making progress to increase the efficiency and durability, as well as lowering the cost, of the key devices that will take advantage of this element (electrolysers and fuel cells). And existing projects in Europe are multiplying, although there are differences between countries —while in Denmark work is already underway to develop cutting-edge green hydrogen plants for transport, in Spain there are currently less than ten.
In May, for example, the first initiative largely financed by the European Union was launched to show how a Power-to-H2-to-Power plant works in practice. The plant produces hydrogen from surplus renewable electricity and stores it until it needs to be converted back into energy for a factory. In this way it replaces up to 100% of the natural gas used for the industrial process. The project, called Hyflexpower, will be carried out in Saillat-sur-Vienne, France, thanks to a partnership between several companies and universities.
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Tungsteno is a journalism laboratory to scan the essence of innovation. Devised by Materia Publicaciones Científicas for Sacyr’s blog.