The technique of producing hydrogen by utilizing green and renewable energy sources is called green hydrogen production. Therefore, by implementing this technique, hydrogen will become a sustainable and clean energy source by lowering greenhouse gas emissions and reducing our reliance on fossil fuels. The key benefit of producing green hydrogen by utilizing green energy is that no harmful pollutants or greenhouse gases are directly released throughout the process. Hence, to guarantee all of the environmental advantages, it is crucial to consider the entire hydrogen supply chain, involving storage, transportation and end users. Hydrogen is a promising clean energy source and targets plan pathways towards decarbonization and net-zero emissions by 2050. This paper has highlighted the techniques for generating green hydrogen that are needed for a clean environment and sustainable energy solutions. Moreover, it summarizes an overview, outlook and energy transient of green hydrogen production. Consequently, its perspective provides new insights and research directions in order to accelerate the development and identify the potential of green hydrogen production.
Nowadays, the technology of renewable-energy-powered green hydrogen production is one method that is increasingly being regarded as an approach to lower emissions of greenhouse gases (GHGs) and environmental pollution in the transition towards worldwide decarbonization [ 1, 2]. However, there is a societal realization that fossil fuels are not zero-carbon, which leads to significant thinking about alternative solutions.
The global energy system ought to drastically change from one mostly reliant on fossil fuels to one that is effective and sustainable with low carbon emissions to meet the goals of the Paris Agreement. Accordingly, >90% is the required global CO2 emission decrease and the projected direct contribution of renewable energy to the necessary emission decrease is 41% [ 3, 4]. Hydrogen (H2) is a cost-effective, environmentally friendly alternative for energy consumption/storage [ 5, 6]. In addition, it can contribute to making a low-carbon society a reality and largely boost the share of hydrogen [ 7].
Hydrogen technologies have been considered an approach to strengthening various economic sectors since the COVID-19 pandemic. The potential of hydrogen is currently the subject of an important consensus, partly due to an increased ambitious climate policy [ 8, 9]. In addition, hydrogen can be used in fuel cell technology in the power generation sector and many other sectors, such as industry, transport and residential applications, which reflects its potential for decarbonization [ 10–12].
Several initiatives and projects worldwide are rapidly rising, reflecting the outstanding political and commercial momentum that the development of hydrogen as a zero-carbon fuel is undergoing. The growing boost is caused by the decreasing cost of hydrogen produced by renewable energy sources, or ‘green hydrogen’, and the urgent need to reduce GHG emissions [ 3, 13]. However, green hydrogen is expected to increase in prominence over the next few decades and attain high commercial viability [ 13, 14]. Producing hydrogen can be done using coal, methane, bioenergy and even solar energy; however, green hydrogen production is one of the pathways [ 15, 16].
Numerous countries consider hydrogen the next-generation energy management response, and they increasingly support adopting hydrogen technology intended to create a decarbonized economy. Therefore, many strategies and plans for developing and implementing hydrogen have been made [ 17].
By 2050, according to Anouti et al. [ 18], there could be 530 million tonnes (Mt) of demand globally for green hydrogen, or hydrogen produced with fewer carbon dioxide emissions. Consequently, it would displace ~10.4 billion barrels of oil, which is equivalent to ~37% of the pre-pandemic world oil production [ 18, 19]. Based on its forecast, the worldwide market for green hydrogen exports may be worth $300 billion annually by 2050, creating ~400 000 jobs in the hydrogen and renewable-energy industries [ 18].
Based on the technique used to produce hydrogen, the energy source used and its effects on the environment, hydrogen is categorized into various colour shades, including blue, grey, brown, black and green [ 20]. Using the steam-reforming/auto-thermal reforming method, grey hydrogen is extracted from natural gas but CO2 is emitted into the atmosphere as a by-product. When the steam-reforming method converts natural gas into hydrogen and the CO2 emissions from the process are captured, this is known as blue hydrogen. The most prevalent type of hydrogen used today is brown hydrogen, mainly produced via the gasification of hydrocarbon-rich fuel, in which CO2 is released into the atmosphere as a by-product. However, green hydrogen is produced by water electrolysis, which is powered by renewable energy resources [ 18, 21, 22].
Green hydrogen is already competitive in regions with all the appropriate conditions [ 15] and will play a significant role in achieving sustainable development goals (SDGs) for the UN 2030, based on the agenda for sustainable development adopted wholly by UN Member States. The specified section of SDG 7 depends on ‘Affordable and Clean Energy’ [ 23, 24]. For this reason, many efforts have been made to attain this goal globally in recent years.
Therefore, continuing on from those issues mentioned above in the introduction, in this paper, we analyse green hydrogen production technologies and investigate several aspects of the significance of the growth of the green hydrogen economy (GEE). The key objective of this study is to highlight the potential and progress of green hydrogen production and its significance in meeting energy needs. The paper is organized as follows. Section 1 summarizes the introduction, Section 2 presents an analysis of the energy transition with green hydrogen, Section 3 details a general overview of green hydrogen production, Section 4 specifics the perspective of green hydrogen energy production and Section 5 summarizes the conclusions and recommendations for future work.
There are several uses for hydrogen, including energy storage, power generation, industrial production and fuel for fuel cell vehicles. Hence, hydrogen production from green energy sources is essential to meet sustainable energy targets (SETs) as the globe attempts to move to a low-carbon economy.
Green hydrogen production requires large amounts of renewable energy and water resources. Thus, areas with an abundance of renewable energy resources, as well as accessibility to water sources, have been determined to be optimal for producing huge amounts of green hydrogen. However, to allow green hydrogen to be more economically viable than fossil fuels, advances in technology and cost reductions must be made.
In order to achieve the target for the expansion of green hydrogen production and utilization, details ought to be established at the level of the authorities. They can facilitate adoption, on the one hand, by increasing manufacturing capacity and guaranteeing an ongoing renewable energy source and, on the other, by increasing the need for green hydrogen alongside its derivatives and developing a system for storing and transporting hydrogen [ 25].
This paper performed a literature review to screen >100 papers related to Google Scholar/Web of Science to consider precisely green energy production by filtering the information in a large number of literature papers in science databases. Figs 1 and 2 illustrate the visualized literature network diagrams; hence, searching for keywords in science databases maps the intensity of relations/strengths among items. The analysis, which determined the research relationships of networks for visualization and exploration, utilized the VOSviewer. The categorical evaluation relies on the occurrence and frequency of keywords in related publications. The red cluster (lower left) represents initial development words trend links, the blue cluster (upper center) represents the second stage of development and the green cluster (lower right) links the green hydrogen words. Fig. 1 displays and signifies the mapping of the intensity of relations among words. In recent years, more research has focused on developing green hydrogen production from 2016 to 2023. Fig. 2 elucidates the keywords of scientific mapping and field trends. The blue cluster (lower left) represents the trend of research development from 2016 to 2019 and the bright maroon cluster (upper right) represents the trend of research development from 2020 to 2023.
Characterizes scientific mapping and relations between words
