Nov-2021

Green hydrogen: a possible path towards a low carbon future

Interest in green hydrogen is reaching unprecedented levels, and the fuel could play an important role in decarbonising hard-to-electrify sectors of the economy.

Dr Himmat Singh
Scientist ‘G’ & Prof (Retd)

Article Summary

Green hydrogen is the new kid on the hydrogen block, and because it is manufactured with renewable energy, it is CO2 free. Such advantages are fuelling interest in green hydrogen globally. Across Europe, Middle East and Asia, companies are embracing this as a high-quality fuel. Countries like China and the US are investing in green hydrogen, primarily to meet their domestic demand. Japan, the first country to adopt a national hydrogen strategy in 2017, gave hydrogen a starring role at the Tokyo 2020 Olympics (held in July 2021) by using it to light the Olympic cauldron.

The global energy system today stands at a point where it will transform energy economics because of rapid technological advances in electrolysers and declining renewable energy costs. Recent PwC estimates for the year 2050, of ‘green hydrogen’ global demand and expected displacement of oil equivalent, exports and expected job creation, add significance to the choice of hydrogen becoming the solution for transporting cheap clean energy across the globe.

This article analyses the developments related to green hydrogen and as a possible path towards a low carbon future.

Introduction
On account of the huge climate change challenge, energy systems are facing a transition towards technologies that result in decreased greenhouse gas (GHG) emissions. Hydrogen is increasingly viewed as a potential saviour in national and international strategies, to be applied to different sectors from industry to transport. As per DNV, hydrogen in 20211 holds the status of a viable and rapidly developing pillar in the energy transition. Over the past few years, hydrogen’s role in the future of energy has grown much more fundamental. Hydrogen, produced from renewable energy sources (RES), has also been proposed as a potential energy carrier to support a wider deployment of low carbon energy. Different waves of enthusiasm have supported the narrative of green hydrogen as the basis of an alternative to fossil fuels by exploiting fuel cell applications in the transport sector. Dedicated hydrogen strategies and research projects are being developed by major world economies^2-5 for addressing different components of the hydrogen pathway.

Among the five different shades of hydrogen, based on production technologies,⁶ green hydrogen, meaning hydrogen produced by RES-based electrolysers, is considered most suitable for a fully sustainable energy transition. The US  promises to use renewable energy to produce green hydrogen that costs less than natural gas, and the Department of Energy is putting up to $100 million into the research and development of hydrogen and fuel cells. The European Union has a strategic plan to invest $430 billion in green hydrogen by 2030 to help achieve the goals of its Green Deal. Chile, Japan, Germany, Saudi Arabia, and Australia are all making major investments into green hydrogen.⁷

Parnell⁸ declared the 2020s as the decade of hydrogen, notable for the rush of activity in the green hydrogen space. As 2020 unfurled and then unraveled, climate change mitigation ambition ramped up. ‘Green recovery’ emerged as a favoured approach to stoking flagging economies. Scott9 writes “seven of the biggest green hydrogen project developers came 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 estimates10 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  

Å’ 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.

Ž Solid oxide electrolysis (SOEC) is a high temperature ceramic cell-based technology to make hydrogen. It is a very efficient, but 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 analysis17 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.

A schematic plan of the world’s largest net-zero emissions synthetic fuel production plant based on green hydrogen being built by Spanish oil major Repsol is shown in Figure 2.18 This electrolysis base facility, to be operational in the next four years, will use cutting-edge technology to combine green hydrogen with CO2 captured in the nearby Petronor refinery, as the raw materials will position Repsol on the leading edge of the development of net-zero emissions fuels.