Hydrogen is today enjoying unprecedented momentum. The world should not miss this unique chance to make hydrogen an important part of our clean and secure energy future. –Dr Fatih Birol, Executive Director of the International Energy Agency
The hydrogen rainbow – how it is produced
Hydrogen is the simplest and most abundant element in the universe. Hydrogen is an energy carrier, not a direct energy source. It can be used to store, move, and deliver energy produced from other sources. Despite its colourless nature, hydrogen has been given many colourful terms – from white to green to pink to black and brown, the ‘hydrogen rainbow’ identifies hydrogen by its source or production process.
White hydrogen is a naturally occurring geological hydrogen found in underground deposits and can be obtained through fracking, a process that cracks open rocks deep underground. Deposits found in Mali and Australia have triggered a global drilling race, but The World Economic Forum says that there are few viable ways of extracting this gas. Grey hydrogen is the most common form and is generated from natural gas, or methane, through a process called steam reforming. This process generates just a smaller amount of emissions than black or brown hydrogen, which uses black (bituminous) or brown (lignite) coal in the hydrogen-making process. Blue hydrogen – referred to as ‘carbon neutral’ – is produced in a similar way to grey hydrogen, but the CO2 is captured and then stored underground through industrial carbon capture and storage (CCS). Green hydrogen, or ‘clean hydrogen’, is produced by using clean energy from surplus renewable energy sources, such as solar or wind power, to split water into two hydrogen atoms and one oxygen atom through a process called electrolysis. Turquoise hydrogen – supposedly coming between blue and green – is created by a thermal process in which natural gas is broken down with the help of methane pyrolysis into hydrogen and solid carbon (instead of CO2 gas). As such, there is no requirement for CCS and the carbon can be used in other applications like tyre manufacturing or as soil improver. Yellow hydrogen refers to hydrogen production from a mixture of renewable energies and fossil fuels. Then there is pink hydrogen. Like green hydrogen, it is created through electrolysis of water but the latter is powered by nuclear energy rather than renewables.
The versatile uses of hydrogen
In 2021, the Energy Transition Commission released its report “Making the Hydrogen Economy Possible: Accelerating clean hydrogen in an electrified economy”, outlining the role of clean hydrogen in achieving a highly electrified net-zero economy. With existing uses today in oil refining, ammonia production, methanol production and steel production, hydrogen use is highly likely to develop in steel, aviation, and power storage.
Cost of hydrogen
Hydrogen is undoubtedly an important building block in achieving a sustainable energy system. Hydrogen is on an unstoppable trajectory, with global production set to more than double by 2030 following public and private sector commitments.
Right now, almost all hydrogen produced worldwide is grey. By 2050 green hydrogen production is likely to cost less in most locations and, in the long run, is the only truly ‘sustainable’ solution. However, blue hydrogen is today the most cost effective low-carbon hydrogen technology, and while concerns have been raised around inefficiencies in the production process causing CO2 to escape, it remains a ‘bridging technology’, particularly in countries lacking the resources to scale-up and/or where distance to trade partners makes imports from neighbouring regions prohibitive.