Green Hydrogen Generation Through Novel Electrolysers Towards Low Carbon Economy: An Opiniated Perspective

1. The Critical Role of Renewable Hydrogen in the Energy Transition

Transitioning to low-carbon technologies is challenging and daunting in the current environment, with significant financial expenditures, new installations and retrofits, and increased energy prices and demand. The goal of decarbonisation in the energy sector is to reduce greenhouse gas emissions into the atmosphere. CO2 emissions are expected to increase to an average of 2.7 ppm/year by 2017, compared to 1.3 ppm/year from 1960 to 2000 (Intergovernmental Panel on Climate Change, 2015) after the 2015 Paris Agreement. Numerous research articles, patents, and opinions about costly low-carbon hydrogen generation methods or conventional hydrogen production have been published. Low-carbon hydrogen generation methods that are cost-effective, efficient, and sustainable are still desperately needed (Abe et al., 2019; Bak et al., 2002a; Cassetti et al., 2023; Chang et al., 2022; Dawood et al., 2020; Figueroa et al., 2008; Q. Yang et al., 2022; W.-J. Yang & Aydin, 2001). These demands can only be satisfied if extensive study and analysis of low-carbon hydrogen is completed. Life cycle assessments of various production methods, environmental impact assessments, and computer studies of multiple production, storage, and risk assessments should be the primary driving forces behind such research. Following the completion of this analysis, low-carbon hydrogen production and storage techniques should be tested sustainably in laboratories before moving on to the next phase of developing effective, reasonably priced, and environmentally friendly methods for producing and storing hydrogen for industrial, educational, and pilot-scale projects (Bak et al., 2002b; Krishnan et al., 2023; Mascarenhas et al., 2019; Sharma et al., 2023; Thomas et al., 2020; Zupone et al., 2015). Once such pilot-scale low-carbon hydrogen projects are established, only such hydrogen energy techniques can be commercialised for sustainable low-carbon economy circulation.

Figure 1. Trend of usage of Hydrogen from 1975-2025 (Intergovernmental Panel on Climate Change, 2015).

Figure 1. Trend of usage of Hydrogen from 1975-2025 (Intergovernmental Panel on Climate Change, 2015).

2. Economic Aspects of Green Hydrogen Electrolysis Technology

Green hydrogen, which will be sold between US$1.5 and US$3.4 per kilogram in 2023, is used in the manufacturing of methanol, electricity generation, fuels and ammonia. However, because it is made from fossil fuels, CO₂ emissions increase. According to IRENA, green hydrogen has a CO₂ capture efficiency of at most 85–95%, which results in 5–15% CO₂ emissions (Clark & Rifkin, 2006). The cost of producing one kilogram of green hydrogen, which is derived by hydrolysing water, ranges from $3 to $7 (Ajanovic et al., 2022a, 2022b; Blanco, 2009). According to Bloomberg New Energy Finance, the cost of green hydrogen will decrease to $1.60 to $2.60 in 2030 and $0.8 to $1.60 in 2050 (Oliveira et al., 2021). While net neutral carbon-based green, turquoise, and blue hydrogen can produce CO₂-reduced hydrogen, research on nanomaterials is crucial for the generation and storage of hydrogen, which will help reduce costs (Bockris, 2013; Chew et al., 2023; Dillman & Heinonen, 2022; Sherif et al., 2005; Tseng et al., 2005). One of the reasons behind this cost reduction, is the subtle transition of conventional energy sources with modern renewables which are affordable, sustainable and efficient. The detailed sustainable hydrogen supply chain management scheme is shown in Figure 2. This method works on the basis of input data delivery, mathematical modelling approach formulation and result analysis (Eh et al., 2022). The figure demonstrates the actuality of the thorough economic aspect which involves an input-output model. For the supply chain management, first a thorough quantification of the raw materials and assess the hydrogen demand of the consumers for which the production system will be setup. The production technologies, and investment operating costs is also analysed with the help of cost-benefit analysis. Once all the input data is collected, then the mathematical modelling approach is conducted on the basis of which output results are conducted entailing around optimal investment plan, location, scale (TRL 1-9) and supply routes.

To analyse the low carbon hydrogen potential, thorough statistics of the current global market of hydrogen demand in billions of USD are necessary. Figure 3 shows the compound annual growth rate pattern from 2022 to 2023; based on these statistics, compound growth of market demand growth is projected until 2028 for a 10.2% compound annual growth rate (CAGR) value. Consecutively. various CAGR projections have to be also stated for several modern renewables as well, and based on the compound annual growth rate, the market demand and value will be assessed for all the energy sources (Bossel and Eliasson, 2022). The projected values of CAGR in Figure 3 for global market value are especially demonstrated for green hydrogen energy, which entails a moderate compound annual growth rate as compared to other modern renewables.

3. Electrolysis for Green Hydrogen Production

In order to improve the quality of the air in the surrounding area and make the transition from fossil fuels to zero-carbon energy systems, hydrogen and fuel cell technologies are very necessary. For the purpose of producing hydrogen, a number of techniques are utilized. These techniques include the electrolysis of water and coal, the steam reforming of natural gas, the creation of hydrogen from petroleum, and the gasification of coal. Only 0.1% of the world's hydrogen is now produced using the age-old process of electrolysis (Naimi & Antar, 2018; Schmidt et al., 2017; Ursua et al., 2012). power is used to divide water into hydrogen and oxygen, and based on the carbon footprint of power, highly pure hydrogen can be created. Green hydrogen can be produced and used as fuel in end uses, such as fuel cell cars, by integrating highly renewable energy sources (REVs), such as solar and wind photovoltaics (Hermesmann & Müller, 2022; Liu et al., 2022; Yu et al., 2021a). However, electrolysis requires 9 litres of water to produce 1 kg of cleaner hydrogen, which can result in a high-water demand, such demand can also be subsequently be solved if there is a continuous hydrogen production reactor used where the used water in the electrolysis system is recycled (Arsad et al., 2023; Proost, 2019; Yue et al., 2021).

Each compartment in the highly modular structure of the electrolyser has 100 cells and dead plant material (Abdin et al., 2021; Yu et al., 2021b). This structure is very useful for the low-carbon hydrogen industrial scale-up process of hydrogen generation; compared to proton membrane electrolysis (PEM) and solid oxide electrolysis (SOE), alkaline electrolysers are more advanced but require less of an investment (Marshall et al., 2007; Pastore et al., 2022; Pletcher & Li, 2011). PEM electrolysers have higher working loads and current densities, whereas SOEs are still in their infancy. Alkaline electrolysers currently cost between $500 and $1,400 per KW to create hydrogen, PEM electrolysers cost between $1,100 and $1,800 per KW, and SOE electrolysers cost between $2,500 and $5,600 per KW. The cost of electrolysers can be decreased to less than $400/KW by increasing their capacity to 70 GW (Lechartier et al., 2015; Ni et al., 2008). To meet these criteria, it is also necessary to produce affordable membrane and electrode materials. Great progress has been made in the field of proton exchange membrane fuel cells (PEMFCs) over the past decade due to their high efficiency, cleanliness, and zero carbon footprint (Tymoczko et al., 2016). However, the high cost, insufficient power density and durability of these materials are major obstacles to their commercialisation and could also be major disadvantages in the industrialisation of low-carbon hydrogen (Bobicki et al., 2012; Griffiths et al., 2021; Hitch & Dipple, 2012; Mittal & Kushwaha, 2024b, 2024a; Taji et al., 2018). Figure 4 demonstrates the various novel electrolysis generators which showcased great potential based on the industrial needs (Baykara, 2018; Panchenko et al., 2023; Ye et al., 2019; S. Zhang et al., 2021). These electrolysis generator processes involve wind mill for hydrogen and power generation, proton exchange membrane electrolysis cells and anion exchange membrane electrolyser. Electrolysis is an age-old technology that accounts for only 0.1% of the world's hydrogen production. By integrating renewable energy sources (REV) such as solar and wind power, green hydrogen can be produced and used as fuel in road and railways governed transport by the application of fuel cells (Gondal et al., 2018; Modisha et al., 2019; Saeidi et al., 2021; X. Zhang et al., 2023).

4. Wind Energy Based Electrolysis

By making several adjustments, a wind energy source, such as a windmill, can also be used to generate electricity and hydrogen (Das et al., 2022; Duan et al., 2023; Maestre et al., 2021; Williams et al., 2019; C. Yang et al., 2019). An electrolyser is essential for producing hydrogen from any electrical source because it combines electricity and water to produce hydrogen and oxygen as designed in Figure 5 (Blaabjerg et al., 2012; Fingersh, 2003; Hansen, 2012; Joselin Herbert et al., 2007; Khalilnejad & Riahy, 2014; Rodrigues et al., 2015).

The wind turbine transforms wind energy into mechanical energy, which is then increased in speed and sent to the generator rotor, which is converted into electrical energy by the gear and coupling system. As there would be only one electrical conversion (from AC to DC), a connected system like this would be less expensive overall and more efficient (Blaabjerg & Ke Ma, 2013; Chen et al., 2009; Mostafaeipour et al., 2016; Rezaei et al., 2020; Snyder & Kaiser, 2009; Zhuang et al., 2023). Wind energy electrolysis showcases immense practical possibilities for industrial applications and projects. Electrolysis of wind energy can reduce grid connection expenses. Infrastructure costs are decreased by self-sufficient units with integrated electrolysers and wind turbines. It also helps mitigate climate change by substituting hydrogen produced from fossil fuels. Wind-generated green hydrogen is useful in several industrial operations, including transportation, steel and metal manufacturing, chemical industries, and refineries. A sustainable hydrogen production method that minimises environmental impact and meets industrial demands is provided by wind energy electrolysis (Armijo & Philibert, 2020; Bosma & Nazari, 2022; Schrotenboer et al., 2022).

5. Proton Exchange Membrane Electrolyser (PEM)

It uses a solid polymer electrolyte membrane to conduct protons (H⁺) while preventing electron migration and operates at low temperatures (approximately 50-80 °C). Green hydrogen production is expensive compared to traditional hydrogen production methods, mainly due to the high cost of renewable energy sources and electrolysis technology (Z. Ma et al., 2021) as engineered in Figure 6.

Electrochemical water splitting is a sustainable method for producing green hydrogen using electrolysis cells, known as electrolysers. These electrolysers can be used with wind energy sources like wind turbines to optimise the power grid. However, alkaline and proton exchange membrane electrolysers face challenges such as handling hydrogen, large structures, and expensive materials (Jiao et al., 2021; Kang et al., 2019; Martinez et al., 2018; Salari et al., 2022).

High NaBH₄ concentrations and reaction rates are necessary for the NaBH₄-PEMFC system to function correctly. To control H₂ generation, the system design should consider PEMFC performance and an additional humidifier. Since the theoretical cell voltage for the electrochemical decomposition of organic molecules is lower than the theoretical cell voltage of water, another strategy that uses biomass feedstock (instead of water) as a source of hydrogen appears to be very promising (Mittal et al., 2024). Although organic biomass-derived raw materials, including alcohols, carboxylic acids, sugars, etc., have been considered hydrogen sources, there has been very little research on the electrochemical breakdown of organic molecules (Han et al., 2015, 2017).

Pt-based catalysts have been studied for the anodic oxidation of ethanol because they can provide fast reaction rates at low voltages. In addition to water, numerous other hydrogen-containing substances can dissociate to create hydrogen, mainly organic substances derived from biomass. Compared to the hydrogen produced by thermal processes, such as SR, ATR, and PrO_x, the electrochemical breakdown of water or an organic substance generates hydrogen of significantly more excellent quality and does not necessitate further exhaust gas purification. since none of the other gases (CO, CO₂, etc.) were present.

Water electrolysis is a process that is almost complete, although it requires a large amount of energy (w⁵ kWh (Nm³)^-1)(Lamy et al., 2014). PEM electrolysers produce high-quality hydrogen, but the widespread use of them will need sustained cost-cutting measures and encouraging legislation. PEM electrolysers are essential to the hydrogen economy as we transition to a sustainable energy source. PEM electrolyser costs are determined by several parameters, including scale, baseline cost estimate, balance of plant (BOP), and stack components. The projected balance of plant (BOP) cost for a 1 MW nameplate electrolyser system is $575/kW.

6. Anion-Exchange Membrane Electrolyser (AEMs)

The anion exchange membrane electrolyser (AEM) has some challenges due to its high hydrogen storage density and compact microcells on large cells. A solid polymeric alkaline membrane is a key component affecting the efficiency of AEM electrolysers (Merle et al., 2011). Research prospects are proposed for finding potential alkaline solid polymer electrolytes for AEM electrolysers. The challenge is finding promising polymeric materials for fabricating alkaline solid polymer membranes (Dekel, 2018; Gottesfeld et al., 2018; Huang et al., 2022; Mustain et al., 2020; Nejati et al., 2018).

Functional groups can enhance ionic conductivity by adding ion pathways and increasing ion exchange capacity. The alkaline solid polymer electrolyte's ability to maintain the AEM electrolyser's operating cell is critical. As the energy transition progresses, there is an urgent need to replace fossil fuels with cleaner, sustainable, and emission-free fuels, and hydrogen generation is one promising possibility as demonstrated in Figure 7 (Ge et al., 2017; M. Ma et al., 2017; Miyata, 1983; Varcoe et al., 2014; Yan et al., 2019).

7. Conclusions

The current advancements in the energy transition and the associated challenges revealed that there is an urgent need to replace fossil fuels with cleaner, sustainable, and zero-net-emission fuels, and one viable option is hydrogen generation. Anion exchange membrane (AEM) electrolysers have been proposed as a remedy to the worst elements of previous electrolyser types due to their high hydrogen storage density, capacity to manufacture compact micro-cells on a large cell scale, and use of non-platinum and non-nafion membrane materials.

One of the viable approaches for manufacturing ecologically friendly hydrogen is electrochemical water splitting. In the hydrogen processing business, alkaline and proton exchange membrane electrolysers have advanced to the advanced commercial level in recent decades. There are several industrial mega-developments in the recent green hydrogen production projects. The industrial green hydrogen market is expanding quickly thanks to strategic investments, policy alignment, and technology advancements. As these enormous advancements take place, green hydrogen is going to be essential to the world's energy transformation. There is also an electrolysis manufacturing scale-up, which involves both the formation of gigafactories and cost reduction. There is an observable rapid increase in the low carbon hydrogen economy markets in India and with more attention towards such electrolysis generation systems, there will be a significant energy alternation transition.