Decarbonisation Technology - November 2021

together to launch the Catapult Initiative in a bid to increase the production of green hydrogen 50-fold in the next six years, with the aim to cut the cost of green hydrogen to less than $2/kg. This would enable decarbonisation of the world’s most carbon-intensive industries; namely, steelmaking, shipping, power production and chemicals. According to recent PwC estimates 10 of ‘green hydrogen’, global demand could reach about 530 million tons (MT) by 2050, displacing roughly 10.4 billion barrels of oil equivalent (around 37% of pre-pandemic global oil production). The green hydrogen export market could be worth US$300 billion yearly by 2050, creating 400,000 jobs globally in RES and hydrogen production. All the above statements suggest that green hydrogen is taking off around the globe. Its promoters claim the fuel could play an important role in decarbonising hard-to-electrify sectors of the economy, such as long-haul trucking, aviation, and heavy manufacturing. Green hydrogen: electrolytic production schemes There are four main electrolysis-based technologies for the manufacture of green hydrogen: 11,12  Alkaline water electrolysis, the most technically mature, is the most commonly seen electrolyser technology today. The electrodes are based on coated metal wire, with the largest current plant being up to 2.5 MW capacity. 13 Such electrolysers, however, do not work well with intermittent RES.  Proton exchange membrane (PEM) electrolysers are the next generation of technology that uses iridium and platinum catalysts coated on to a proton-conducting membrane, similar to the technology Johnson Matthey uses today in fuel cells for a variety of applications. Compared with alkaline water electrolysis, PEM are more able to cope with the intermittent nature of electricity from wind or solar and have a significantly smaller footprint. ITM Power Ltd has secured a joint venture project with Shell to construct a 10 MW electrolyser in the Rhineland Refinery Complex in Germany. 14 The working mechanism of PEM is shown in Figure 1 .  Solid oxide electrolysis (SOEC) is a high temperature ceramic cell-based technology to make hydrogen. It is a very efficient, but

+ –

Bipolar plates

Operating process

Voltage applied between electrodes

+ + H ions travel towards the cathode 3 2H capture 2e from the cathode and combine to produce H 4 2HO gives up electrons at the anode to produce 4H ions and O 2 –

technically less mature, especially in processes where waste heat is available.  Anion exchange membrane (AEM) electrolysers are still in development, but share many of the benefits of PEM and rely on advanced nickel catalysts rather than precious metals. For all electrolysis, there is a requirements to fulfill a number of different goals – high efficiency (85-95%) and hydrogen production rate, long life span, low capital cost, provide grid balancing for renewable generation and compactness – which all present challenges and research needs. 15,16 Frost & Sullivan’s recent analysis 17 forecasts that global green hydrogen production will skyrocket at a compound annual growth rate (CAGR) of 57% between 2019-2030, rising from 40,000 tons to 5.7 MT. This jump is due to increasing concerns about carbon emissions driving the need to decarbonise major industrial sectors, thereby reducing countries’ dependency on fossil fuel- based systems and increasing investments across alternate technologies, including green hydrogen. Figure 1 How polymer electrolyte membrane technology works 10 Source: O Schmidt, A Gambhir, I Staffell, A Hawkes, J Nelson, S Few, Future cost and performance of water electrolysis: An expert elicitation study, International Journal of Hydrogen Energy , 42 (2017), 30470-30492; International Energy Agency, The Future of Hydrogen: Seizing today’s opportunities, Jun 2019 (www.iea.org/ reports/the-future-of-hydrogen); strategy& analysis