Electrification from renewable sources is the best solution for the energy transition to decarbonization – that is, the abatement of greenhouse gases, caused mainly by the use of fossil fuels, which are causing the climate crisis. But we have an important ally: green hydrogen, which is indispensable for reducing harmful emissions in some specific sectors. Let's see what’s is all about. Why exactly hydrogen, and what is it used for? The use of electricity from renewable sources – solar, wind, hydroelectric, geothermal – is essential in the fight against climate change: for example, replacing gasoline, diesel, or LPG cars with electric vehicles, changing gas heating systems in buildings to high-efficiency heat pumps, replacing conventional kitchen equipment with induction cooktops, and so on. However, there are sectors where large amounts of energy are consumed in a short time, and which are difficult, at least for the time being, to power with electricity: for example, large industries, or long-distance shipping or air transportation. Entirely new strategies are needed to reduce emissions in these areas. One solution is hydrogen, the lightest and most abundant element in the universe (and it’s also the fuel in the nuclear fusions of stars!). Are all the methods for producing hydrogen the same? Hydrogen has a big advantage over other fuels because when it burns it doesn’t emit carbon dioxide, only pure water. On Earth it’s present in abundance, but never on its own: it’s in water bound with oxygen, in methane together with carbon, and even in coal. But to produce usable hydrogen, it’s necessary - obviously - to separate it from the other elements to which it’s bound. The colors assigned to hydrogen are a way of identifying and differentiating the ways it’s produced: they all yield the same molecule with the same properties, but they have different impacts on the environment. So-called brown hydrogen, for example, is produced by coal gasification, and for every kilogram of hydrogen extracted, more than 20 kilograms of carbon dioxide are emitted. Gray hydrogen, which is derived from methane, puts 9 kilograms of carbon dioxide into the atmosphere for every kilogram of hydrogen produced. There’s one method, however, that has no cost to the environment: it uses the process of electrolysis to separate hydrogen from oxygen in water molecules; it’s called green hydrogen. As the color suggests, producing it results in no carbon dioxide emissions. Is green hydrogen already being produced? There’s already a huge production of hydrogen on Earth today, amounting to 75 million tons per year, because it’s used as a raw material in various activities, including refining processes. But in most cases it’s brown or gray hydrogen, with impacts on the environment that are equal to the emissions of the United Kingdom and Indonesia combined. Producing green hydrogen is already possible at the moment, but at very high economic costs because electrolyzers are not yet produced on a large scale. However, what has already happened in other renewable sectors may also happen for this technology. For example, photovoltaic panels now cost 9 times less than they did 10 years ago, and predictions tell us that something similar is about to happen for green hydrogen.
