Grey hydrogen, blue hydrogen, green hydrogen – what’s it all about and what makes one more environmentally friendly than another?
Hydrogen is a fuel that needs an energy source for it to be produced, unlike alternatives such as petroleum. Hydrogen is typically produced in one of two ways – using electricity to split water and oxygen in a process known as electrolysis, or by heating methane (known as steam reforming). Once produced, hydrogen can be burnt directly to provide power, or mixed with oxygen to form a fuel cell. Historically nuclear power as well as fossil fuels have been used to kick start the process of generating hydrogen, so it’s interesting to see its recent growth in popularity as a new emerging future green energy alternative. To understand how this has come about, we’ll need to understand what the difference is between each of the colours.
The colour is the term used to describe the production method. Hydrogen is a colourless gas, so colours are used as a reference term to distinguish between production processes. Grey hydrogen is created from a natural gas source, and emits damaging CO2 emissions as a by-product. For this reason it’s not a sustainable or environmentally friendly option to use – as well as being expensive compared with traditional power generation techniques.
Blue hydrogen is also derived from natural gas, but some of the carbon dioxide that is produced can be captured and stored to help reduce its impact on the environment – however not all of it can be removed from the energy production process.
The introduction of green hydrogen though, has helped to create a much more environmentally friendly, climate neutral way to produce hydrogen – using renewable energy sources as the electricity source to split water into hydrogen and oxygen through an electrolyser, with zero CO2 emitted in the process. Making it a much more sustainable and greener hydrogen option. Now thanks to the increased focus on onshore and offshore wind farms, renewable energy is much more readily available to use in the green hydrogen production process, so across the globe we’re seeing more organisations looking at how they can adopt hydrogen as a fuel. From heavy industry such as steelmaking, to transport, hydrogen is becoming increasingly popular as a viable option to decarbonise operations.
Scaling up UK production
Examples of projects in the UK include HyNet North West and the H2H Saltend, as well as H2Teesside.
Furthermore, a number of hydrogen refuelling stations have already been operational for vehicles to top up for a number of years now – although it has not yet been widely adopted. Whilst last year saw the introduction of the first new homes to be built with hydrogen powered household appliances such as the boiler, hob and cooker. With the Government’s UK Hydrogen Strategy setting themselves an ambitious target of 5GW low carbon production capacity by 2030.
The global outlook
The picture is similar across the globe, with hundreds of future hydrogen projects being investigated, including Saudi Arabia’s green hydrogen project on NEOM – which will be the world’s largest commercially-based, utility scale hydrogen facility to be fully powered by renewables. 4GW of solar and wind energy will be used to produce the green hydrogen, with an expected output of 650 tonnes per day once operational in 2025.
Other global projects currently at the EPC stage include Ørsted’s 2MW Avedøre Hydrogen Project in Denmark, and ENGIE’s Sines Hydrogen Project in Portugal which will see a 10MW electrolysis pilot plan installed and further aspirations to increase capacity to 1GW by 2030. These are just a few examples of projects across the world, with plans for hydrogen production spanning the globe as far as Egypt, Slovakia, Oman, Kazakhstan and South Africa. As projects enter their decision-making stages in the coming months and years, the future looks incredibly interesting for hydrogen power.
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