- You have probably heard of hydrogen and know that it is the most abundant element in the universe. But did you know that hydrogen can be utilised as an energy and fuel source? Hydrogen can be used in a variety of different sectors including industry and transport. It can reduce the carbon footprint of fertiliser production, allow the storage of energy from solar panels and wind turbines, and be used as a fuel for vehicles.
Hydrogen has a lot of potential as a clean fuel — but as with everything, it's important that we produce and use it in the most environmentally responsible way possible. According to the International Energy Agency, 70 million tonnes of hydrogen are currently consumed worldwide. The problem is that almost all of it is produced from coal or natural gas, which releases pollution into the atmosphere during extraction. ACCIONA's goal is to champion the production and use of green hydrogen, replacing polluting models and helping decarbonise energy for a greener future.
What is hydrogen?
Hydrogen is the most abundant chemical element on the planet — first in the periodic table, with the atomic number 1. It's present in 75% of all matter and is always found in the company of other elements like oxygen (in water) and carbon (in organic compounds). It's light, storable, and produces no pollution by itself, which makes it a strong candidate as a fuel source.
However, hydrogen is not a primary energy source — it's an energy vector. That means it requires a chemical process to produce it and turn it into fuel. Green hydrogen is produced without generating pollutant emissions, using a process called electrolysis. Electricity from renewable sources like wind and solar splits water into two elements — hydrogen and oxygen — with no greenhouse gases released.
Why is everyone talking about it?
Green hydrogen is set to become one of the biggest shifts in the renewable energy economy. Unlike grey or blue hydrogen, green hydrogen has a zero carbon footprint. There is a growing consensus that it could replace fossil fuels across almost every sector — from industry to transport — helping eliminate the world's reliance on polluting gases.
Hydrogen initiatives are already advancing in Europe, with investment in competitive electrolysis processes, transport infrastructure, and hydrogen-powered road vehicles. According to the International Renewable Energy Agency, the cost of hydrogen installations could fall by 40–80% in the future. Combined with falling renewable energy prices, green hydrogen could become cost-competitive with fossil fuels by 2040.
What are the different types of hydrogen and what do the colours mean?
Hydrogen is a colourless gas, but the industry uses colour codes to identify how it was produced — not how it looks. Different colours correspond to different production methods.
The three most common types are grey, blue, and green hydrogen.
Grey
Currently the most common and cheapest form of hydrogen production, grey hydrogen is created from natural gas via steam reforming. The process separates hydrogen from natural gas, but the resulting carbon emissions are not captured — they're released into the atmosphere.
Blue
Blue hydrogen is also produced via steam reforming, but the carbon emissions are captured and stored — reducing atmospheric impact without eliminating it. It's sometimes called 'low-carbon hydrogen' because it doesn't prevent greenhouse gas creation; it stores it away.
Green
Green hydrogen uses renewable energy in its production, generating no emissions across its entire life cycle. Clean electricity from surplus wind or solar splits water into hydrogen and oxygen — no carbon released. It's the most sustainable option, with the main challenge being reducing production costs to make it broadly accessible.