Insights into low-carbon hydrogen production methods: Green,blue and aqua hydrogen

The primary aim of this study is to provide insights into different low-carbon hydrogen production methods. Low-carbon hydrogen includes green hydrogen (hydrogen from renewable electricity), blue hydrogen (hydrogen from fossil fuels with CO₂ emissions reduced by the use of Carbon Capture Use and Storage) and aqua hydrogen (hydrogen from fossil fuels via the new technology). Green hydrogen is an expensive strategy compared to fossil-based hydrogen. Blue hydrogen has some attractive features, but the CCUS technology is high cost and blue hydrogen is not inherently carbon free. Therefore, engineering scientists have been focusing on developing other low-cost and low-carbon hydrogen technology. A new economical technology to extract hydrogen from oil sands (natural bitumen) and oil fields with very low cost and without carbon emissions has been developed and commercialized in Western Canada. Aqua hydrogen is a term we have coined for production of hydrogen from this new hydrogen production technology. Aqua is a color halfway between green and blue and thus represents a form of hydrogen production that does not emit CO₂, like green hydrogen, yet is produced from fossil fuel energy, like blue hydrogen. Unlike CCUS, blue hydrogen, which is clearly compensatory with respect to carbon emissions as it captures, uses and stores produced CO₂, the new production method is transformative in that it does not emit CO₂ in the first place. In order to promote the development of the low-carbon hydrogen economy, the current challenges, future directions and policy recommendations of low-carbon hydrogen production methods including green hydrogen, blue hydrogen, and aqua hydrogen are investigated in the paper.     

Global hydrogen development - A technological and geopolitical overview

Hydrogen is an energy carrier that will certainly make an important and decisive contribution to the global energy transition and lead to a significant reduction in greenhouse gas (GHG) emissions over the coming decades. It is estimated that 60% of GHG emission reductions in the last phase of the energy transition could come from renewables, green hydrogen and electrification based on green energy development. Coordinated efforts by governments, industry and investors, as well as substantial investment in the energy sector, will be required to develop the hydrogen value chain on a global scale. This paper summarizes the technical and technological advances involved in the production, purification, compression, transportation and use of hydrogen. We also describe the roadmaps and strategies that have been developed in recent years in different countries for large-scale hydrogen production.     

Techno-economic model and feasibility assessment of green hydrogen projects based on electrolysis supplied by photovoltaic PPAs

The use of hydrogen produced from renewable energy enables the reduction of greenhouse gas (GHG) emissions pursued in different international strategies. The use of power-purchase agreements (PPAs) to supply renewable electricity to hydrogen production plants is an approach that can improve the feasibility of projects. This paper presents a model applicable to hydrogen projects regarding the technical and economic perspective and applies it to the Spanish case, where pioneering projects are taking place via photovoltaic PPAs. The results show that PPAs are an enabling mechanism for sustaining green hydrogen projects.     

The sustainability of green hydrogen: An uncertain proposition

Green hydrogen is increasingly considered a vital element for the long-term decarbonization of the global energy system. For regions with scarce land resources, this means importing significant volumes of green hydrogen from regions with abundance of renewable energy. In producing countries, this raises significant sustainability questions related to production and export. To assess these sustainability-related opportunities and challenges, the authors first present a review of renewable energy deployment in the electricity sector, and then extend it to the foreseeable opportunities and risks of green hydrogen production in exporting countries. The paper finds that questions of freshwater and land availability are critical from an environmental and a socio-economic point of view, and that the development of international standards for the governance of hydrogen-related projects will be crucial. These should also address potential conflicts between the deployment of renewable energy for the decarbonization of local power grids, and the export of green hydrogen.     

Prospects for the production of green hydrogen: Review of countries with high potential

The article provides a review of the current hydrogen production and the prospects for the development of the production of “green” hydrogen using renewable energy sources in various countries of the world that are leaders in this field. The potential of hydrogen energy in such countries and regions as Australia, the European Union, India, Canada, China, the Russian Federation, United States of America, South Korea, the Republic of South Africa, Japan and the northern countries of Africa is considered. These countries have significant potential for the production of hydrogen and “green” hydrogen, in particular through mining of fossil fuels and the use of renewable energy sources. The quantitative indicators of the production of “green” hydrogen in the future and the direction of its export are considered; the most developed hydrogen technologies in these countries are presented. The production of “green” hydrogen in most countries is the way to transition from the consumption of fossil fuels to the clean energy of the future, which will significantly improve the environmental situation, reduce greenhouse gas emissions and improve the energy independence of the regions.     

A review on hydrogen production and utilization: Challenges and opportunities

Environment-friendly, safe and reliable energy supplies are indispensable to society for sustainable development and high life quality where even though social, environmental, political and economic challenges may play a vital role in their provision. Our continuously growing energy demand is driven by extensive growth in economic development and population and places an ever-increasing burden on fossil fuel utilization that represent a substantial percentage of this increasing energy demand but also creates challenges associated with increased greenhouse gas (GHG) emissions and resource depletion. Such challenges make the global transition obligatory from conventional to renewable energy sources. Hydrogen is emerging as a new energy vector outside its typical role and receiving more recognition globally as a potential fuel pathway, as it offers advantages in use cases and unlike synthetic carbon-based fuels can be truly carbon neutral or even negative on a life cycle basis. This review paper provides critical analysis of the state-of-the-art in blue and green hydrogen production methods using conventional and renewable energy sources, utilization of hydrogen, storage, transportation, distribution and key challenges and opportunities in the commercial deployment of such systems. Some of the key promising renewable energy sources to produce hydrogen, such as solar and wind, are intermittent; hydrogen appears to be the best candidate to be employed for multiple purposes blending the roles of fuel energy carrier and energy storage modality. Furthermore, this study offers a comparative assessment of different non-renewable and renewable hydrogen production systems based on system design, cost, global warming potential (GWP), infrastructure and efficiency. Finally the key challenges and opportunities associated with hydrogen production, storage, transportation and distribution and commercial-scale deployment are addressed.     

Abating transport GHG emissions by hydrogen fuel cell vehicles: Chances for the developing world

Fuel cell vehicles, as the most promising clean vehicle technology for the future, represent the major chances for the developing world to avoid high-carbon lock-in in the transportation sector. In this paper, by taking China as an example, the unique advantages for China to deploy fuel cell vehicles are reviewed. Subsequently, this paper analyzes the greenhouse gas (GHG) emissions from 19 fuel cell vehicle utilization pathways by using the life cycle assessment approach. The results show that with the current grid mix in China, hydrogen from water electrolysis has the highest GHG emissions, at 3.10 kgCO₂/km, while by-product hydrogen from the chlor-alkali industry has the lowest level, at 0.08 kgCO₂/km. Regarding hydrogen storage and transportation, a combination of gas-hydrogen road transportation and single compression in the refueling station has the lowest GHG emissions. Regarding vehicle operation, GHG emissions from indirect methanol fuel cell are proved to be lower than those from direct hydrogen fuel cells. It is recommended that although fuel cell vehicles are promising for the developing world in reducing GHG emissions, the vehicle technology and hydrogen production issues should be well addressed to ensure the life-cycle low-carbon performance.     

Resource assessment for green hydrogen production in Kazakhstan

Kazakhstan has long been regarded as a major exporter of fossil fuel energy. As the global energy sector is undergoing an unprecedented transition to low-carbon solutions, new emerging energy technologies, such as hydrogen production, require more different resource bases than present energy technologies. Kazakhstan needs to consider whether it has enough resources to stay competitive in energy markets undergoing an energy transition. Green hydrogen can be made from water electrolysis powered by low-carbon electricity sources such as wind turbines and solar panels. We provided the first resource assessment for green hydrogen production in Kazakhstan by focusing on three essential resources: water, renewable electricity, and critical raw materials. Our estimations showed that with the current plan of Kazakhstan to keep its water budget constant in the future, producing 2–10 Mt green hydrogen would require reducing the water use of industry in Kazakhstan by 0.6–3% or 0.036–0.18 km³/year. This could be implemented by increasing the share of renewables in electricity generation and phasing out some of the water- and carbon-intensive industries. Renewable electricity potential in South and West Kazakhstan is sufficient to run electrolyzers up to 5700 and 1600 h/year for wind turbines and solar panels, respectively. In our base case scenario, 5 Mt green hydrogen production would require 50 GW solar and 67 GW wind capacity, considering Kazakhstan's wind and solar capacity factors. This could convert into 28,652 tons of nickel, 15,832 tons of titanium, and many other critical raw materials. Although our estimations for critical raw materials were based on limited geological data, Kazakhstan has access to the most critical raw materials to support original equipment manufacturers of low-carbon technologies in Kazakhstan and other countries. As new geologic exploration kicks off in Kazakhstan, it is expected that more deposits of critical raw materials will be discovered to respond to their potential future needs for green hydrogen production.     

中国2050年低碳情景和低碳发展之路

利用IPAC模型对我国未来中长期的能源与温室气体排放情景进行分析。设计了3个排放情景,介绍了情景的主要参数和结果,以及实现减排所需的技术,同时探讨中国实现低碳情景所需要的发展路径。作为一个经济快速增长国家,中国未来的能源需求和相应的温室气体排放将快速明显增加。中国要实现低碳发展路径,必须从现在就采取适合于低碳发展的政策,着重发展具有国际领先地位的重大清洁能源开发、转换和利用技术,大力发展可再生能源和核电技术,提高公众意识,使低碳生活方式成为普遍行为,逐步实施能源税和碳税。     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

非化石能源制氢技术综述

在现今的经济社会和未来的低碳经济中H2将发挥重要作用.非化石能源制氢是化石能源短缺和温室气体排放等约束下的可持续制氢路径.综述了可再生电力电解制氢、核能制氢、太阳能制氢和生物质能制氢等四种非化石能源制氢技术的工作原理、流程设备和技术特点,最后对我国未来非化石能源制氢的路线选择进行了评论.     

Prospects and challenges for green hydrogen production and utilization in the Philippines

The Philippines is exploring different alternative sources of energy to make the country less dependent on imported fossil fuels and to reduce significantly the country's CO₂ emissions. Given the abundance of renewable energy potential in the country, green hydrogen from renewables is a promising fuel because it can be utilized as an energy carrier and can provide a source of clean and sustainable energy with no emissions. This paper aims to review the prospects and challenges for the potential use of green hydrogen in several production and utilization pathways in the Philippines. The study identified green hydrogen production routes from available renewable energy sources in the country, including geothermal, hydropower, wind, solar, biomass, and ocean. Opportunities for several utilization pathways include transportation, industry, utility, and energy storage. From the analysis, this study proposes a roadmap for a green hydrogen economy in the country by 2050, divided into three phases: I–green hydrogen as industrial feedstock, II–green hydrogen as fuel cell technology, and III–commercialization of green hydrogen. On the other hand, the analysis identified several challenges, including technical, economic, and social aspects, as well as the corresponding policy implications for the realization of a green hydrogen economy that can be applied in the Philippines and other developing countries.     

A systematic review on green hydrogen for off-grid communities –technologies,advantages, and limitations

Approximately 3.5 billion people worldwide lack reliable and sustainable energy services, mostly in poor off-grid areas of developing countries. Variable renewable energies are options for these communities. However, their high intermittence and complex storage limit their benefits. Green hydrogen research has advanced significantly to the point that some scholars consider it the future's clean energy solution. Multiple applications within the transport, electricity and storage sectors have been envisaged. However, little has been discussed about its potential to provide affordable, dependable, and sustainable energy for the world's poorest. This paper addresses this gap by analyzing the literature on green hydrogen research, its technologies, and its potential implementation in off-grid communities. First, a quantitative bibliometric approach is developed to size and make sense of the green hydrogen research literature. Then, an in-depth review is performed following Dawood et al.'s four-corners framework, categorizing hydrogen research into production, storage, use, and safety. This systematic review unveils green hydrogen's most promising technologies for off-grid applications. It identifies their advantages, limitations, and barriers to widespread dissemination. Thus, this study's primary contributions lie in determining the relationship between published works and identifying gaps in considering green hydrogen as a viable energy alternative for the poor.     

The emerging hydrogen economy and its impact on LNG

Hydrogen is gaining prominence as a critical tool for countries to meet decarbonisation targets. The main production pathways are based on natural gas or renewable electricity. LNG represents an increasingly important component of the global natural gas market. This paper examines synergies and linkages between the hydrogen and LNG values chains and quantifies the impact of increased low-carbon hydrogen production on global LNG flows. The analysis is conducted through interviews with LNG industry stakeholders, a review of secondary literature and a scenario-based assessment of the potential development of global low-carbon hydrogen production and LNG trade until 2050 using a novel, integrated natural gas and hydrogen market model. The model-based analysis shows that low-carbon hydrogen production could become a significant user of natural gas and thus stabilise global LNG demand. Furthermore, commercial and operational synergies could assist the LNG industry in developing a value chain around natural gas-based low-carbon hydrogen.     

Preparation of hydrogen from metals and water without CO2 emissions

Considering the high calorific value and low-carbon characteristics of hydrogen energy, it will play an important role in replacing fossil energy sources. The production of hydrogen from renewable energy sources for electricity generation and electrolysis of water is an important process to obtain green hydrogen compared with classic low-carbon hydrogen production methods. However, the challenges in this process include the high cost of liquefied hydrogen and the difficulty of storing hydrogen on a large scale. In this paper, we propose a new route for hydrogen storage in metals, namely, electricity generation from renewable energy sources, electrolysis to obtain metals, and subsequent hydrogen production from metals and water. Metal monomers facilitate large-scale and long-term storage and transportation, and metals can be used as large-scale hydrogen storage carriers in the future. In this technical route, the reaction between metal and water for hydrogen production is an important link. In this paper, we systematically summarize the research progress, development trend, and challenges in the field of metal to hydrogen production. This study aim to aid in the development of this field.     

Prospects and challenges of renewable hydrogen generation in Bangladesh

The collective endeavor in reaching net-zero emissions by 2050 and halting the impending effects of global warming has found a promising solution-hydrogen, a clean energy carrier with diversified applications. It is practical to transition H₂ production at scale from fossil fuels to renewable sources. The choice of appropriate hydrogen production route from renewables would regionally vary, depending on various factors. While a majority of the developed countries have kickstarted their transition towards a hydrogen economy, developing countries like Bangladesh have been lagging. This review explores the potential of a hydrogen-based energy system for Bangladesh - commencing with a technological comparison of existing production paths from renewable resources; then moving on to a preliminary analysis of its available resources and technology options. Finally, a roadmap toward a hydrogen economy is envisioned, as the foundation for further study and public policy initiatives aimed at hastening Bangladesh's transition to a carbon-free energy system.     

Review and comparison of various hydrogen production methods based on costs and life cycle impact assessment indicators

Hydrogen is a clean, renewable secondary energy source. The development of hydrogen energy is a common goal pursued by many countries to combat the current global warming trend. This paper provides an overview of various technologies for hydrogen production from renewable and non-renewable resources, including fossil fuel or biomass-based hydrogen production, microbial hydrogen production, electrolysis and thermolysis of water and thermochemical cycles. The current status of development, recent advances and challenges of different hydrogen production technologies are also reviewed. Finally, we compared different hydrogen production methods in terms of cost and life cycle environmental impact assessment. The current mainstream approach is to obtain hydrogen from natural gas and coal, although their environmental impact is significant. Electrolysis and thermochemical cycle methods coupled with new energy sources show considerable potential for development in terms of economics and environmental friendliness.     

Recognizing the role of uncertainties in the transition to renewable hydrogen

Achieving the goal of net zero emissions targeted by many governments and businesses around the world will require an economical zero-emissions fuel, such as hydrogen. Currently, the high production cost of zero emission ‘renewable’ hydrogen, produced from electrolysis powered by renewable electricity, is hindering its adoption. In this paper, we examine the role of uncertainties in projections of techno-economic factors on the transition from hydrogen produced from fossil fuels to renewable hydrogen. We propose an integrated framework, linking techno-economic and Monte-Carlo based uncertainty analysis with quantitative hydrogen supply-demand modelling, to examine hydrogen production by different technologies, and the associated greenhouse gas (GHG) emissions from both the feedstock supply and the production process. The results show that the uncertainty around the cost of electrolyser systems, the capacity factor, and the gas price are the most critical factors affecting the timing of the transition to renewable H₂. We find that hydrogen production will likely be dominated by fossil fuels for the next few decades if the cost of carbon emissions are not accounted for, resulting in cumulative emissions from hydrogen production of 650 Mt CO₂-e by 2050. However, implementing a price on carbon emissions can significantly expedite the transition to renewable hydrogen and cut the cumulative emissions significantly.     

Systematic planning to optimize investments in hydrogen infrastructure deployment

The introduction of hydrogen infrastructure and fuel cell vehicles (FCVs) to gradually replace gasoline internal combustion engine vehicles can provide environment and energy security benefits. The deployment of hydrogen fueling infrastructure to support the demonstration and commercialization of FCVs remains a critical barrier to transitioning to hydrogen as a transportation fuel. This study utilizes an engineering methodology referred to as the Spatially and Temporally Resolved Energy and Environment Tool (STREET) to demonstrate how systematic planning can optimize early investments in hydrogen infrastructure in a way that supports and encourages growth in the deployment of FCVs while ensuring that the associated environment and energy security benefits are fully realized. Specifically, a case study is performed for the City of Irvine, California – a target area for FCV deployment – to determine the optimized number and location of hydrogen fueling stations required to provide a bridge to FCV commercialization, the preferred rollout strategy for those stations, and the environmental impact associated with three near-term scenarios for hydrogen production and distribution associated with local and regional sources of hydrogen available to the City. Furthermore, because the State of California has adopted legislation imposing environmental standards for hydrogen production, results of the environmental impact assessment for hydrogen production and distribution scenarios are measured against the California standards. The results show that significantly fewer hydrogen fueling stations are required to provide comparable service to the existing gasoline infrastructure, and that key community statistics are needed to inform the preferred rollout strategy for the stations. Well-to-wheel (WTW) greenhouse gas (GHG) emissions, urban criteria pollutants, energy use, and water use associated with hydrogen and FCVs can be significantly reduced in comparison to the average parc of gasoline vehicles regardless of whether hydrogen is produced and distributed with an emphasis on conventional resources (e.g., natural gas), or on local, renewable resources. An emphasis on local renewable resources to produce hydrogen further reduces emissions, energy use, and water use associated with hydrogen and FCVs compared to an emphasis on conventional resources. All three hydrogen production and distribution scenarios considered in the study meet California's standards for well-to-wheel GHG emissions, and well-to-tank emissions of urban ROG and NO_X. Two of the three scenarios also meet California's standard that 33% of hydrogen must be produced from renewable feedstocks. Overall, systematic planning optimizes both the economic and environmental impact associated with the deployment of hydrogen infrastructure and FCVs.     

Emerging technologies by hydrogen: A review

The majority of energy being used is obtained from fossil fuels, which are not renewable resources and require a longer time to recharge or return to its original capacity. Energy from fossil fuels is cheaper but it faces some challenges compared to renewable energy resources. Thus, one of the most potential candidates to fulfil the energy requirements are renewable resources and the most environmentally friendly fuel is Hydrogen. Hydrogen is a clean and efficient energy carrier and a hydrogen-based economy is now widely regarded as a potential solution for the future of energy security and sustainability. Hydrogen energy became the most significant energy as the current demand gradually starts to increase. It is an important key solution to tackle the global temperature rise. The key important factor of hydrogen production is the hydrogen economy. Hydrogen production technologies are commercially available, while some of these technologies are still under development. Therefore, the global interest in minimising the effects of greenhouse gases as well as other pollutant gases also increases. In order to investigate hydrogen implementation as a fuel or energy carrier, easily obtained broad-spectrum knowledge on a variety of processes is involved as well as their advantages, disadvantages, and potential adjustments in making a process that is fit for future development. Aside from directly using the hydrogen produced from these processes in fuel cells, streams rich with hydrogen can also be utilised in producing ethanol, methanol, gasoline as well as various chemicals of high value. This paper provided a brief summary on the current and developing technologies of hydrogen that are noteworthy.