Lucky are those who can happily drop into conversation such concepts as non-fungible tokens, digital twins, or cryptic lineages and know what they are talking about.
Lucky are those who can happily drop into conversation such concepts as non-fungible tokens, digital twins, or cryptic lineages and know what they are talking about. There is now a danger that the spectrum of half a dozen or more colours used to characterise hydrogen power’s alternative energy credentials, real or potential, are in danger of falling into this category of obtuseness. For example, hands up those who know what turquoise hydrogen is.
The good thing perhaps is that the hydrogen community has already departed from the seven colours of the rainbow leaving themselves plenty of scope for christening new processes for producing hydrogen. To date the hydrogen kaleidoscope includes green, blue, grey, black, brown, pink, purple, turquoise and white. By contrast, naming of the seemingly endless variants of the Covid virus may soon hit the buffers: the medical world obviously believed that the Greek alphabet would suffice. The looming problem is that researchers have already got to Omicron having skipped all the letters from Delta to Omicron and so now only have a few usable letters left.
Any confusion over the hydrogen colour chart is by no means as frivolous as it may seem. A paper prepared for the World Energy Council, in collaboration with Electric Power Research Institute and PwC, calls for more dialogue warning that ‘colour has been used to simplify the conversation about the carbon footprint of hydrogen production, but it has become more complex with no universally agreed colours for specific technologies and some disagreement as to which colour matches which supply.’
That this confusion should arise at all is especially ironic given that hydrogen itself is an invisible gas, and should it achieve more familiar everyday usage will probably have to be accorded a distinctive coloured flame like the blue flame on a kitchen gas stove. More importantly, the debate about hydrogen production nomenclature is emblematic of the slow development of what arguably should be one of the key sources of energy with the potential to save the planet.
According to Science Direct ‘hydrogen, as a clean energy carrier for heat and electricity, has many appealing characteristics, including a large storage capacity, high energy conversion, cleanliness and environmental friendliness, renewable production, vast specific energy, zero emissions, wide sources, reliability, and easy storage and regeneration.’
So what’s been taking so long? The simple answer is that up to now grey hydrogen has taken care of some 70% all the world use of hydrogen, confined principally to the refining and petrochemical sector. It is created from natural gas, or methane, using steam methane reformation (SMR) with significant CO2 emissions. Much of the remaining global hydrogen production balance has been sourced from black coal or lignite (brown coal) using the same basic process which is even more environmentally unfriendly. In 2019 the IEA put the total emission count from hydrogen production at around 830 Mtpa of CO2.
Hydrogen has multiple uses although most people probably only know about the limited use of hydrogen fuel cells to power cars and buses and maybe are aware of the unfortunate fate of the Hindenburg hydrogen-filled airship in 1937. In fact hydrogen is mainly produced in situ, i.e. not yet seriously transportable. In the chemical industry it is used to make ammonia for agricultural fertiliser (the Haber process) and cyclohexane and methanol, which are intermediates in the production of plastics and pharmaceuticals. It is also used to remove sulphur from fuels during the oil-refining process; to hydrogenate oils to form fats, for example to make margarine; in the glass industry as a protective atmosphere for making flat glass sheets; in the electronics industry as a flushing gas during the manufacture of silicon chips, etc, etc.
These days the goal of course is to harness hydrogen without the impact on the atmosphere. Blue hydrogen derived from natural gas through the process of steam methane reforming (SMR) has provided a partial solution. SMR mixes natural gas with very hot steam, in the presence of a catalyst, where a chemical reaction creates hydrogen and carbon monoxide. Additional water is added to the mixture converting the carbon monoxide to carbon dioxide and creating more hydrogen. The carbon dioxide emissions produced are then captured and stored underground using carbon capture, utilisation and storage (CCUS) technology leaving nearly pure hydrogen. Believed to be the largest project of its kind, plans have been announced to develop a blue energy complex worth $4.5 billion in Louisiana, USA. It is expected to produce more than 750 million standard ft3/d of blue hydrogen. A portion of the blue hydrogen will be compressed and supplied to production facilities. In Louisiana and Texas via a hydrogen pipeline network. Around 95% of the CO2 generated at the facility – expected to be operational in 2026 – will be captured, compressed and transported by pipeline to multiple inland sequestration sites, with more than five million metric tonnes per year of CO2 permanently stored.
The attraction of blue hydrogen is the cost of production. The raw material is natural gas (and can be in abundant supply), and the CCS technology is proven. But it is still reliant on fossil fuels. This is why all the focus is turning towards green hydrogen, made by using clean electricity from surplus renewable energy sources, such as solar or wind power, to electrolyse water. The electrolysers use an electrochemical reaction to split water into its components of hydrogen and oxygen, emitting zero-carbon dioxide in the process.
In his highly readable The Hydrogen Revolution: A blueprint for the future of clean energy (a Financial Times Book of the Year in 2021) Marco Alverà agues that hydrogen is stuck in the chicken and egg predicament where supply is awaiting demand and vice versa. ‘If hydrogen is to realise its full potential it needs to be ample, cheap, easy to transport, store and distribute – and we also need plenty of hydrogen trains, trucks, steel mills and boilers that can make the most of its precious energy … To break out of this, hydrogen must become cheap enough to compete with fossil fuels, at least in some applications.’ That clearly is a big ask. However, Alverà, CEO of the Italian energy infrastructure company Snam, is convinced that the prospects of hydrogen can and will be transformed into reality by focusing on bringing down the cost of production and distribution of green hydrogen.
According to Alverà, green hydrogen from electrolysis costs about $5/kg ($125MWh) in areas of the world where renewables (wind and solar) are abundant. Blue hydrogen comes in at $2.5/kg ($60/MWh), while highly polluting grey hydrogen is cheapest at $2/kg ($50/MWh). Alverà believes the tipping point will be around $2/kg but realises that the cost and availability of renewable power and electrolysis remain a major investment deterrent along with the need for infrastructure to make hydrogen available. He puts some faith in the learning rate that posits that as production scales up, so costs come down. Wind turbines have improved at a 12% learning rate, photovoltaic technology (solar) 24% and the expectation for electrolyser learning rate is 18%.
Alverà is of course an unashamed advocate for hydrogen as a major contributor to climate change mitigation. However, there is growing evidence that industry and investors are beginning to see things his way.
The July 2021 updated Hydrogen Insights report prepared by McKinsey & Co for the Hydrogen Council identified 359 hydrogen projects underway worldwide with evidence of many other projects in early development. More than 80% of new projects are located in Europe. McKinsey estimates that the total associated investment in hydrogen through 2030 will amount to $500 billion, based on $130 billion investment directly associated with the announced projects, $120 billion needed to reach government targets, and $250 billion implied investment from OEMs and suppliers. Seventy per cent of the announced production capacity comes from renewable energy sources, while the other 30% is low-carbon hydrogen generated by fossil fuels combined with CCS.
Numerous recent studies argue that the pivot to hydrogen will require government support and incentives. This is beginning to happen. In 2020, ten governments (Canada, Chile, France, Germany, the Netherlands, Norway, Portugal, Russia, Spain and the European Union) had adopted hydrogen strategies. As of September 2021, Czech Republic, Colombia, Hungary and the UK) had joined the club so to speak. In addition, Poland and Italy have released strategies for public consultation and more than 20 other countries have announced they are actively developing theirs, notably Australia, Saudi Arabia and Chile.
Meantime back to the colours. Pink hydrogen is generated through electrolysis powered by nuclear energy, sometimes referred to as purple hydrogen or red hydrogen. Yellow hydrogen is said to mean hydrogen made through electrolysis using solar power, and then there is turquoise hydrogen, requiring a yet to be proven process called methane pyrolysis to produce hydrogen and solid carbon, which can either be permanently stored or used.
Most intriguing of all is white hydrogen – natural or native are other names. This is naturally-occurring geological hydrogen found in underground deposits which may have been overlooked in the past and could prove transformational. In Earth Science Reviews (April 2020) Viacheslav Zgonnik concludes that hydrogen of geologic origin has the potential to become the renewable energy source of the future. His company Natural Hydrogen Energy claims that its 2019 well was the first throughout all of the Americas to purposely drill for natural hydrogen.
Hopefully consideration of white hydrogen’s potential is not just hot air.
‘Confusion over hydrogen colour is by no means frivolous’
‘Most intriguing of all is white hydrogen’
