Decoding Green Hydrogen: An Evolutionary Lens on Electrolyzer Innovation

For centuries, Oil and Gas have been the key driving force in propelling societal advancement. From the steam engine to the assembly line, the industrial revolution has formed the backbone of modern civilization. However, owing to the drastic spike in carbon emissions, it has also warmed the earth's temperature by over 1.1 degrees Celsius since then.  

Facets such as an increasing ecological toll due to climate change and derelict energy security implore the need to find an alternative energy source. Intensifying geopolitical tensions, market fluctuations and strained trade relations contribute to the urgency of this task.

This sets the stage for hydrogen: a contender that has long held promise in leading the charge towards an energy transition. It offers an enticing prospect: a clean, abundant fuel that emits no carbon emissions upon combustion.  

The term "hydrogen economy" was etched in literature as early as 1972 in a paper titled 'The Hydrogen Economy: An Ultimate Economy?'.

There were compelling reasons to support this notion.

Hydrogen has the highest gravimetric energy density compared to traditional fossil fuels. Although its applications are pervasive, they can be explored under a few overarching themes:  

• Decarbonizing hard-to-abate sectors where energy-intensive applications cannot be electrified. This includes high-temperature industrial processes, steel and chemical production, and long-haul mobility where electrification is difficult, impractical, and expensive.  
• Enabling sector coupling by bridging the gap for efficient energy consumption and integrating renewables for the utilization of excess energy through long-term, stable storage.   
• Facilitating fuel switching through the overhaul of pre-existing infrastructure as well as blending solutions for gradual, net positive change in processes. 

Over 95% of the world's hydrogen requirement is fulfilled through 'Grey hydrogen'. This method of production - Steam Methane Reforming (SMR), emits almost a billion tons of carbon dioxide emissions. This process utilizes natural gas, mostly methane, and produces syngas, which is further purified to obtain hydrogen. It is then wielded across various downstream applications as a fuel or feedstock.    

Hydrogen continues to be utilized, but to harness the truly "clean" nature in its entirety, a process called electrolysis gained prominence. It utilizes a basic chemical reaction: renewable electricity passes through water to split the molecules into hydrogen and oxygen. When produced this way through devices called electrolyzers, it is popularly known as 'green hydrogen.' 

However, this was not an easy process to standardize commercially. It underwent several crucial iterations that contributed to its growing adoption feasibility. 

By 1900, there were already over 400 alkaline electrolyzers in operation, mainly for ammonia production using low-cost electricity from hydropower. While diaphragms such as asbestos were initially used for gas separation, towards the mid-century, the industry widely adopted zirconium oxide separators or membranes.

Close to the 1980s, the applications were expanded to spaceship programs and military life-support applications in submarines. This was primarily due to a breakthrough in polymer chemistry that led to the invention of PEM electrolyzers. 

Technological advancements are often not made in a vacuum. They are influenced by supportive or disruptive external factors such as policy evolution, international trade relations, and the competitive landscape. As the space race came to an end towards the end of the century, other mainstream opportunities had to be explored for electrolyzers.  

This involved working on several aspects: design, scalability, cost, and efficiency.    

A durable system with over 50,000 hours of lifetime was eventually developed. However, several challenges persisted.

Two of them were high costs and a lack of renewable infrastructure. But as renewables such as PV grew over 14x while reducing over 82% in costs in the last decade, the green ecosystem continued to grow more resilient.  

The last-generation electrolyzers, post-2020, are built upon an expectation of gigawatt-level deployment and unmatched efficiency. This will be an evolving research-based exercise, supported by rapid offtake agreements, a refined circular economy, and technological breakthroughs.  It is optimistic to note that the trends leading up to renewable credence now mirror the current trajectory of electrolyzers.  

However, regardless of the regulatory support, the slow rate of active deployment at lower capex is a cause for concern. Grey hydrogen is available at $1-3/kg, while green hydrogen costs are still over $6/kg at the minimum, ranging up to $15/kg, where the costs of RES (Renewable Energy Sources) are higher. 

To reach Net-Zero goals, the International Energy Agency forecasts an installed electrolyzer capacity of over 550 GW by 2030. This is challenging, primarily because the current capacity is simply 2.9 GW. Moreover, even if the projects announced by 2023 were to be realized, it would lead to an installed capacity of 170-365 GW, which is far from ideal.

This sheds a spotlight on two main probable pathways moving forward: improvising upon commercially proven technologies such as Alkaline and PEM, and building new breakthrough technologies that solve their insurmountable challenges.

Let's take a brief look at these aspects. 

Alkaline forms 40% of the current installed technology. From the vantage point of decades of R&D, testing, validation, and insights from iterative feedback loops, it has a definite head start in terms of commercialization. Although megawatt scale projects exist, there are significant operational challenges that need to be resolved.

One of them is a limited operating range flexibility during integration with wide-range RESs. This typically means the system cannot be efficient when there are fluctuations in the renewable power supply, such as from wind. Additionally, the frequent start-stops to ensure safety degrade the stability and power quality of the electrical system, which affects the stack lifespan.

Long-term shutdowns also tend to devalue the potential of electrodes due to reverse current flow. While a few of these challenges can be accommodated partly through rectifiers, it adds significant cost and complexity. In comparison to PEM, they also offer lower efficiencies, which may not be suitable for particular use cases. 

PEM electrolyzers, on the other hand, are an industrial powerhouse. They offer the highest system efficiencies but are too expensive for wide-scale adoption. They typically utilize PGM-group metals as catalysts, which contribute up to 30% of the stack costs.

Another pressing concern is the uncertain future their proprietary membrane holds. Nafion is a type of per- and polyfluoroalkyl substance (PFAS) that is known for features such as high hydrophobicity and chemical resistance. However, in early 2023, the EU proposed a ban on the use of this chemical due to health risks and high environmental persistence.

When in effect, this ban would gravely challenge the future status of Nafion as a benchmark polymer for PEM electrolyzers. 

While industry giants and MNCs work on refining these technologies, it also opens doors for modernization and technology overhaul. Despite the competitive global landscape, this collective undertaking only adds to the decarbonization effort - and every bit helps when the climate deadline is unchanging and urgent. 

Newtrace emerged from one such ideology. Green hydrogen as the leading clean energy source in hard-to-abate sectors is rarely a matter of debate among experts.

However, upon a technical evaluation of insufficient uptake, two key areas withhold growth: the usage of membranes and rare-earth metals. This forms the bedrock of the innovative technology being developed at Newtrace. 

Membranes are fragile by their innate composition and often require additional auxiliary components. This may include a sophisticated control system and a pure water treatment plant to manage the influence of load fluctuations, impurities, and mechanical stress.     

By the order of their physical properties, they allow for a certain percentage of diffusion across hydrogen and oxygen sides. In conventional systems such as Alkaline, the flow rate of the electrolyte remains constant. During times of elevated energy generation during the day, such as from solar, the system's production is high.

However, when the electrical energy being provided to the system is lower and it is pushed outside of its optimal turndown ratio (range between the maximum and minimum operating capacities), the impurities in the separated gases increase due to lower overall production.  

In a membraneless system, this factor is impervious to change and is controlled primarily by flow rates. This ensures that the electrolyzer stays efficient and produces a higher quality output for prolonged operating hours.  

The other impediment is finding an alternative for rare-earth metals such as platinum and iridium. While they are chemically inert, versatile, and less prone to deactivation, their high costs and supply chain risks pose significant challenges while scaling up.

Aided by other design innovations, the transition metal-based electrocatalyst developed by Newtrace is able to provide high efficiencies while eliminating aforementioned challenges.   

Through our newsletter, we aim to provide a clear and comprehensive overview of the hydrogen landscape and empower stakeholders, decision-makers, and climate enthusiasts in their journey towards decarbonization.

In subsequent editions, we will explore the technology components in depth, demystify hard-to-abate sectors, and validate the irreplaceable role that green hydrogen is bound to play in the upcoming decades.

Author: Karnika K. , Senior Associate - Founder's Office.