“Green” path from fossil-based to hydrogen economy: An overview of carbon-neutral technologies

While the dominant role of hydrogen in a sustainable energy future is widely accepted, the strategies for the transition from fossil-based to hydrogen economy are still actively debated. This paper emphasizes the role of carbon-neutral technologies and fuels during the transition period. To satisfy the world's growing appetite for energy and keep our planet healthy, at least 10 TW (or terawatt) of carbon-free power has to be produced by mid-century. Three prominent options discussed in the literature include: decarbonization of fossil energy, nuclear energy and renewable energy sources. These options are analyzed in this paper with a special emphasis on the role of hydrogen as a carbon-free energy carrier. In particular, the authors compare various fossil decarbonization strategies and evaluate the potential of nuclear and renewable energy resources to meet the 10 TW target. An overview of state-of-the-art technologies for production of carbon-free energy carriers and transportation fuels, and the assessment of their commercial potential is provided. It is shown that neither of these three options alone could provide 10 TW of carbon-neutral power without major changes in the existing infrastructure, and/or technological breakthroughs in many areas, and/or a considerable environmental risk. The authors propose a scenario for the transition from current fossil-based to hydrogen economy that includes two key elements: (i) changing the fossil decarbonization strategy from one based on CO₂ sequestration to one that involves sequestration and/or utilization of solid carbon, and (ii) producing carbon-neutral synthetic fuels from bio-carbon and hydrogen generated from water using carbon-free sources (nuclear, solar, wind, geothermal). This strategy would allow taking advantage of the existing fuel infrastructure without an adverse environmental impact, and it would secure a smooth carbon-neutral transition from fossil-based to future hydrogen economy.     

Barrier identification,analysis and solutions of hydrogen energy storage application in multiple power scenarios based on improved DEMATAL-ISM approach

China is ambitiously moving towards “carbon emission peak” and “carbon neutral” targets, and the power sector is in the vanguard. The coordination of power and hydrogen energy storage (HES) can improve energy utilization rate, promoting the deep decarbonization of power industry and realizing energy cascade utilization. However, limited by technology, cost, environment, society and other factors there are few application projects. Identifying major barriers and eliminating unimportant factors can make problem solving more efficient. Decision-making trial and evaluation laboratory (DEMATEL) combined with interpretative structural modeling (ISM) method is innovatively used to establish a barrier analysis framework for HES applied in multiple power scenarios. This method can show the direction and degree of the impact relationship between barriers and determine key ones, which is conducive to presenting targeted and effective solutions. Additionally, the interval type-2 fuzzy set (IT2FS) is introduced to reduce the distortion of evaluation information and ensure the rationality of analysis. Specifically, a comprehensive barrier system taking into account both commonalities and characteristics is established firstly. For different decision considerations, four typical power scenarios are screened to better illustrate how critical barriers play different roles in different scenarios. Then, the proposed analytical framework is applied to identify the key barriers in each scenario and find out the interlinking relationship among the barriers. The results suggest that technical barriers tend to dominate the fundamental barriers. Among that, immature hydrogen storage and transportation technology is a prevalent and fundamental barrier. Besides, high initial investment cost and high P2X conversion costs are crucial reasons that prevent relevant investors from entering the market. And inadequate policy has led to a poor environment for HES development. It's worth noting that, other key barriers focused on each scenario are not the same, and also are discussed in detail in this study. Finally, comprehensive solutions and policy suggestions to eliminate or reduce the barriers are presented.     

A review of four case studies assessing the potential for hydrogen penetration of the future energy system

Hydrogen as an energy carrier allows the decarbonization of transport, industry, and space heating as well as storage for intermittent renewable energy. The objective of this paper is to assess the future engineering potential for hydrogen and provide insight to areas of research to help lower economic barriers for hydrogen adoption. This assessment was accomplished by creating top-level system models based on energy requirements for end-use services. Those models were used to investigate four case studies that provide a global view augmented with specific national examples. The first case study assesses the potential penetration of hydrogen using a global energy system model. The second applies the dynamic integrated climate–ecosystem–economics model to derive an estimate of the impact of the diffusion of hydrogen as an energy carrier. The third determines the required growth in renewable power and water usage to power transportation in the United States (US) with hydrogen. The fourth assesses the use of hydrogen for heating in the United Kingdom (UK). In all cases, there appeared to be significant potential for hydrogen adoption and net energetic benefit. Globally, hydrogen has the potential to account for approximately 3% of energy consumption by 2050. In the US, using hydrogen for on-road transportation could enable a reduction in rejected energy of nearly 10%. Also, hydrogen might provide the least cost alternative to decarbonizing space heating in the UK. The research highlights a challenge raised by widespread abandonment of nuclear power. It is currently unclear what the removal of nuclear would do to the cost of energy as nations attempt to limit global greenhouse gas emissions. Nuclear power has also been proposed as a source for large scale production of hydrogen. Finally, this analysis shows that with today's technological maturity making the transition to a hydrogen economy would incur significant costs.     

Towards a low carbon energy future – Renewable energy cooperation between Germany and Norway

Renewable energy is a cornerstone of German climate change policies. Germany has adopted particularly ambitious renewable energy targets, and is now implementing an Energiewende – a transition to a nuclear-free and low-carbon energy system. The transition could be eased through European cooperation. This article investigates the economic, political, environmental and technological factors that act as drivers and barriers to renewable energy cooperation between Germany and Norway. The article finds that German actors see Norwegian electricity as a means for enhancing the stability of their electricity system as Germany shifts to a greater reliance on renewables. In Norway the picture is more mixed. Norwegian state-owned electricity producers and grid operators are interested in cooperation largely out of profit motives, but expect Germany to create a favorable environment for investors. Energy-intensive industries and consumers on the other hand, are afraid that more electricity cooperation with Germany will raise electricity prices. The Norwegian environmental movement is split on the issue. Parts of the movement see renewable energy cooperation as an important step towards a European low-carbon energy future. Nature and outdoor organizations, however, argue that new renewable energy infrastructure, including pumped-storage hydropower, will result in major environmental impacts. If cooperation is to be achieved, these economic and environmental concerns will have to be taken seriously.     

The economics and the environmental benignity of different colors of hydrogen

Due to the increasing greenhouse gas emissions, as well as due to the rapidly increasing use of renewable energy sources in the electricity generation over the last years, interest in hydrogen is rising again. Hydrogen can be used as a storage for renewable energy balancing the whole energy systems, and contributing to the decarbonization of the energy system, especially of the industry and the transport sector.The major objective of this paper is to discuss various ways of hydrogen production depending on the primary energy sources used. Moreover, the economic and environmental performance of three major hydrogen colors, as well as major barriers for faster deployment in fuel cell vehicles, are analyzed.The major conclusion is that the full environmental benefits of hydrogen use are highly dependent on the hydrogen production methods and primary sources used. Only green hydrogen with electricity from wind, PV and hydro has truly low emissions. All other sources like blue hydrogen with CCUS or electrolysis using the electricity grid have substantially higher emissions, coming close to grey hydrogen production. Another conclusion is that it is important to introduce an international market for hydrogen to lower costs and to produce hydrogen where conditions are best.Finally, the major open question remaining is whether – including all external costs of all energy carriers, hydrogen of any color may become economically competitive in any sector of the energy system. The future success of hydrogen is very dependent on technological development and resulting cost reductions, as well as on future priorities and the corresponding policy framework. The policy framework should support the shift from grey to green hydrogen.     

Steady-state analysis of a natural gas distribution network with hydrogen injection to absorb excess renewable electricity

Natural gas networks, thanks to their extensiveness and capillarity, could play a crucial role in the green transition of the energy sector. The decarbonization of a gas network can be achieved by injecting green hydrogen into the grid. This work aims to simulate a low-pressure natural gas distribution network serving industrial and residential users and subjected to one localized injection of hydrogen produced by renewable energy sources. The main quality indexes and fluid dynamics parameters of the gas mixture are analysed to understand the feasibility of injecting hydrogen into a natural gas network. Firstly, the network was examined under nominal steady conditions with a constant hydrogen injection. Then, the same grid was simulated considering a 24-h pattern of hydrogen injection, according to the power daily surplus. The results show that the grid can help to buffer the surplus of renewable power produced. The conclusions derived by the results underline that the effect of H2 injection is maximum during the highest excess of electricity and the importance of an accurate choice of the injection node: a wrong choice leads, at the peak of power production, leads to an amplification of the H2 injection impact and hence to a reduction of the Wobbe Index value that overcomes the safety lower limit.     

Towards a hydrogen economy in Poland

The global changes in energy policy, including the increasing contribution of renewable sources of energy to the total output of produced energy and various attempts to introduce advanced energy technologies, and the increasingly efficient use of the energy that had already been emitted are sufficient reasons to discuss Poland's energy policy. The present work features an analysis of the current state of Poland's energy economy and the economic factors that affect the power industry. The tenets of Poland's current energy policy are also presented in the context of hydrogen energy. The possibilities and limitations concerning the transition to hydrogen power in Poland are discussed taking into account a number of aspects, some of which include the degree of development of the electric power infrastructure, the current and future demand for electric energy with regard to the current geopolitical and economic situation of Poland, and Poland's membership in the European Union.     

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.     

Hydrogen energy deployment in decarbonizing transportation sector using multi-supply-demand integrated scenario analysis with nonlinear programming — A Shanxi case study

Peaking CO₂ emissions and reaching carbon neutrality create a major role for hydrogen in the transportation field where decarbonization is difficult. Shanxi, as a microcosm of China in the systematic transformation of energy end-use consumption, is selected to investigate the hydrogen energy development forecast for decarbonization in the transportation sector. Multi-supply-demand integrated scenario analysis with nonlinear programming (NLP) model is established to analyze hydrogen energy deployment in varied periods and regions under minimum environmental, energy and economic objectives, to obtain CO₂ emission reduction potential. Results reveal that green hydrogen contributes most to low-carbon hydrogen development strategies. In high-hydrogen demand scenarios, carbon emission reduction potential is significantly higher under environmental objectives, estimated at 297.68 × 10⁴–848.12 × 10⁴ tons (2025–2035). The work provides a strategy to forecast hydrogen energy deployment for transportation decarbonization, being of vital significant guide for planning of hydrogen energy transportation in other regions.     

The performance of the Norwegian carbon dioxide,capture and storage innovation system

In order to take up Norway's twin challenge of reducing CO₂ emissions, while meeting its growing energy demand with domestic resources, the deployment of carbon capture and storage (CCS) plays an important role in Norwegian energy policies. This study uses the Functions of Innovation Systems approach to identify key policy issues that need to be addressed in order to prolong Norway's international leadership position in the development of CCS. The analysis shows that Norway has been successful in building an innovation system around CCS technology. The key determinants for this achievement are pinpointed in this article. However, the evolution of the innovation system seems to have entered a critical phase that is decisive for a further thriving development of CCS in Norway. The results provide a clear understanding of the current impediments in the CCS innovation system and stress the need to direct policy initiatives at the identified weak system functions—i.e. entrepreneurial activity and market formation—to improve the performance of the system. We discuss how policymakers can use these insights to develop a coherent set of policy instruments that would foster the deployment of CCS concepts related to power production and enhanced oil recovery in Norway.     

Primary and secondary control of an autonomous solar microgrid based power-to-X: Renewable hydrogen conversion

The desire of achieving carbon neutrality and the decarbonization objective is the key driver for the interest in green hydrogen for power plant generation as a clean and flexible energy carrier. In fact, the use of hydrogen-based generating plants as hydrogen fuel cells in solar microgrids plays a major role in the energy transition and adds more reliability to this type of microgrid. This study presents a hierarchical control level 1 and 2 of an islanded microgrid with green hydrogen production, storage, and re-electrification. The purpose of this article is to control a stand-alone/off-grid microgrid with renewable hydrogen storage-based non-dispatchable sustainable energy solutions. An energy management strategy was implemented and a primary and secondary control was applied in order to maintain the voltage and frequency of the islanded microgrid at their steady state values.     

The production of hydrogen fuel from renewable sources and its role in grid operations

Understanding the scale and nature of hydrogen's potential role in the development of low carbon energy systems requires an examination of the operation of the whole energy system, including heat, power, industrial and transport sectors, on an hour-by-hour basis. The Future Energy Scenario Assessment (FESA) software model used for this study is unique in providing a holistic, high resolution, functional analysis, which incorporates variations in supply resulting from weather-dependent renewable energy generators. The outputs of this model, arising from any given user-definable scenario, are year round supply and demand profiles that can be used to assess the market size and operational regime of energy technologies. FESA was used in this case to assess what - if anything - might be the role for hydrogen in a low carbon economy future for the UK.In this study, three UK energy supply pathways were considered, all of which reduce greenhouse gas emissions by 80% by 2050, and substantially reduce reliance on oil and gas while maintaining a stable electricity grid and meeting the energy needs of a modern economy. All use more nuclear power and renewable energy of all kinds than today's system. The first of these scenarios relies on substantial amounts of ‘clean coal’ in combination with intermittent renewable energy sources by year the 2050. The second uses twice as much intermittent renewable energy as the first and virtually no coal. The third uses 2.5 times as much nuclear power as the first and virtually no coal.All scenarios clearly indicate that the use of hydrogen in the transport sector is important in reducing distributed carbon emissions that cannot easily be mitigated by Carbon Capture and Storage (CCS). In the first scenario, this hydrogen derives mainly from steam reformation of fossil fuels (principally coal), whereas in the second and third scenarios, hydrogen is made mainly by electrolysis using variable surpluses of low-carbon electricity. Hydrogen thereby fulfils a double facetted role of Demand Side Management (DSM) for the electricity grid and the provision of a ‘clean’ fuel, predominantly for the transport sector. When each of the scenarios was examined without the use of hydrogen as a transport fuel, substantially larger amounts of primary energy were required in the form of imported coal.The FESA model also indicates that the challenge of grid balancing is not a valid reason for limiting the amount of intermittent renewable energy generated. Engineering limitations, economic viability, local environmental considerations and conflicting uses of land and sea may limit the amount of renewable energy available, but there is no practical limit to the conversion of this energy into whatever is required, be it electricity, heat, motive power or chemical feedstocks.     

Utilization of green ammonia as a hydrogen energy carrier for decarbonization in spark ignition engines

Rising concerns about the dependence of modern energy systems on fossil fuels have raised the requirement for green alternate fuels to pave the roadmap for a sustainable energy future with a carbon-free economy. Massive expectations of hydrogen as an enabler for decarbonization of the energy sector are limited by the lack of required infrastructure, whose implementation is affected by the issues related to the storage and distribution of hydrogen energy. Ammonia is an effective hydrogen energy carrier with a well-established and mature infrastructure for long-distance transportation and distribution. The possibility for green ammonia production from renewable energy sources has made it a suitable green alternate fuel for the decarbonization of the automotive and power generation sectors. In this work, engine characteristics for ammonia combustion in spark ignition engines have been reported with a detailed note on engines fuelled with pure ammonia as well as blends of ammonia with gasoline, hydrogen, and methane. Higher auto-ignition temperature, low flammability, and lower flame speed of ammonia have a detrimental effect on engine characteristics, and it could be addressed either by incorporating engine modifications or by enhancing the fuel quality. Literature shows that the increase in compression ratio from 9.4:1 to 11.5:1 improved the maximum power by 59% and the addition of 10% hydrogen in supercharged conditions improved the indicated efficiency by 37%. Challenges and strategies for the utilization of ammonia as combustible fuel in engines are discussed by considering the need for technical advancements as well as social acceptance. Energy efficiency for green ammonia production is also discussed with a due note on techniques for direct synthesis of ammonia from air and water.     

A review of hydrogen utilization in power generation and transportation sectors: Achievements and future challenges

Decarbonizing the power generation and transportation sectors, responsible for ∼65% of Green House Gas (GHG) emissions globally, constitutes a crucial step to addressing climate change. Accordingly, the energy paradigm is shifting towards carbon-free and low-emission alternative fuels. Even though the current decarbonization using hydrogen is not large since 96% of global hydrogen production is relying on conventional fossil fuels that produce GHGs in the process, hydrogen fuel has been considered a promising fuel for fuel cell and combustion engines. Various renewable approaches utilizing biomass and water have been investigated to produce green hydrogen. With this, recent developments showed viability to achieve deep decarbonization in the power generation and transportation sectors. Hydrogen-powered vehicles are commercially available in many countries, and over 300,000 fuel cell appliances were sold to produce hot water and electricity. This review aims to provide an overview of the potential role of hydrogen in power generation and transportation systems, recent achievements in research development, and technical challenges to successfully applying hydrogen as a primary fuel. Especially this review will focus on the hydrogen application in power generation and transportation sectors using fuel cells, gas turbines, and internal combustion engines (ICEs).     

Techno-economic evaluation of medium scale power to hydrogen to combined heat and power generation systems

The European Hydrogen Strategy and the new « Fit for 55 » package indicate the urgent need for the alignment of policy with the European Green Deal and European Union (EU) climate law for the decarbonization of the energy system and the use of hydrogen towards 2030 and 2050. The increasing carbon prices in EU Emission Trading System (ETS) as well as the lack of dispatchable thermal power generation as part of the Coal exit are expected to enhance the role of Combined Heat and Power (CHP) in the future energy system. In the present work, the use of renewable hydrogen for the decarbonization of CHP plants is investigated for various fossil fuel substitution ratios and the impact of the overall efficiency, the reduction of direct emissions and the carbon footprint of heat and power generation are reported. The analysis provides insights on efficient and decarbonized cogeneration linking the power with the heat sector via renewable hydrogen production and use. The levelized cost of hydrogen production as well as the levelized cost of electricity in the power to hydrogen to combined heat and power system are analyzed for various natural gas substitution scenarios as well as current and future projections of EU ETS carbon prices.     

Hydrogen in energy transition: A review

The energy transition is not something that awaits us in the next decade. On the contrary, it is a process in which we are already deeply enrolled. The main step towards the creation of a carbon-neutral society is the implementation of renewable energy sources (RES) as replacements for fossil fuels. Given the intermittency of RES, energy storage has an essential role to play in this transition. Hydrogen technology with its many advances was recognized to be the most promising choice. As multiple hydrogen applications were researched relatively recently, the current development of its technology is not yet on the large-scale implementation level. With the increasing number of studies and initiated projects, the utilization of hydrogen's immense ecological potential is to be expected in the next few decades. New innovative solutions of hydrogen technology that includes hydrogen production, storage, distribution, and usage, are permeating all industry sectors. In a rapidly changing world, technological advances bring forth public discussions, that are a deciding factor whether society will be able to adapt and accept those new contributions or reject them. Currently, hydrogen is the best associated with fuel cell electric vehicles which emit only water vapour and warm air, producing no harmful tailpipe emissions. As various scientists are stressing the gravity of climate change effects that are reaching the physical environment, ecosystems, and humanity in general, concern for the future is becoming the main global topic. Consequently, governments are implementing new sustainable policies that promote RES as a substitute for fossil fuels. Increasing progress in hydrogen technology instigated nations worldwide to incorporate hydrogen in their energy legislations and national development plans, which resulted in numerous national hydrogen strategies. This work shows the progress of hydrogen taking its place as a key factor of the future green energy society. It reviews recent developments of hydrogen technologies, their social, industrial, and environmental standing, as well as the stage of transitioning economies of both advanced and beginner countries. An example of the ongoing energy transition is Croatia, which is in the process of implementing a hydrogen strategy with the ambition to be able to one day equally participates in the rapidly emerging hydrogen market.     

A hydrogen economy: opportunities and challenges

A hydrogen economy, the long-term goal of many nations, can potentially confer energy security, along with environmental and economic benefits. However, the transition from a conventional petroleum-based energy system to a hydrogen economy involves many uncertainties, such as the development of efficient fuel-cell technologies, problems in hydrogen production and its distribution infrastructure, and the response of petroleum markets. This study uses the US MARKAL model to simulate the impacts of hydrogen technologies on the US energy system and to identify potential impediments to a successful transition. Preliminary findings highlight possible market barriers facing the hydrogen economy, as well as opportunities in new R&D and product markets for bioproducts. Quantitative analysis also offers insights on policy options for promoting hydrogen technologies.     

氢储能调峰站发展路径探索研究

氢储能是解决可再生能源消纳和缓解峰谷电差的有效方式之一,通过电转氢技术可以实现规模化、长期、广域的储能。借助我国电网基建优势,谷电时段将可再生能源丰富地区电能输送到高纯氢需求中心,在用户端电解制氢,提高输电通道利用率,解决氢气远距离运输成本、安全等关键问题。本文介绍了氢储能现状,给出了氢储能调峰站典型设计方案,分析了在高纯氢需求中心建设氢储能调峰站的技术和经济可行性。同时提出氢储能调峰站潜在的风险与挑战,并给出发展建议。     

Towards sustainable energy systems: The related role of hydrogen

The role of hydrogen in long run sustainable energy scenarios for the world and for the case of Germany is analysed, based on key criteria for sustainable energy systems. The possible range of hydrogen within long-term energy scenarios is broad and uncertain depending on assumptions on used primary energy, technology mix, rate of energy efficiency increase and costs degression (“learning effects”). In any case, sustainable energy strategies must give energy efficiency highest priority combined with an accelerated market introduction of renewables (“integrated strategy”). Under these conditions hydrogen will play a major role not before 2030 using natural gas as a bridge to renewable hydrogen. Against the background of an ambitious CO₂-reduction goal which is under discussion in Germany the potentials for efficiency increase, the necessary structural change of the power plant system (corresponding to the decision to phase out nuclear energy, the transformation of the transportation sector and the market implementation order of renewable energies (“following efficiency guidelines first for electricity generation purposes, than for heat generation and than for the transportation sector”)) are analysed based on latest sustainable energy scenarios.     

Market penetration analysis of hydrogen vehicles in Norwegian passenger transport towards 2050

The Norwegian energy system is characterized by high dependency on electricity, mainly hydro power. If the national targets to reduce emissions of greenhouse gases should be met, a substantial reduction of CO₂ emissions has to be obtained from the transport sector. This paper presents the results of the analyses of three Norwegian regions with the energy system model MARKAL during the period 2005–2050. The MARKAL models were used in connection with an infrastructure model H2INVEST. The analyses show that a transition to a hydrogen fuelled transportation sector could be feasible in the long run, and indicate that with substantial hydrogen distribution efforts, fuel cell cars can become competitive compared to other technologies both in urban (2025) and rural areas (2030). In addition, the result shows the importance of the availability of local energy resources for hydrogen production, like the advantages of location close to chemical industry or surplus of renewable electricity.