Exploring supply chain design and expansion planning of China's green ammonia production with an optimization-based simulation approach

Green ammonia production as an important application for propelling the upcoming hydrogen economy has not been paid much attention by China, the world's largest ammonia producer. As a result, related studies are limited. This paper explores potential supply chain design and planning strategies of green ammonia production in the next decade of China with a case study in Inner Mongolia. A hybrid optimization-based simulation approach is applied, considering traditional optimization approaches are insufficient to address uncertainties and dynamics in a long-term energy transition. Results show that the production cost of green ammonia will be at least twice that of the current level due to higher costs of hydrogen supply. Production accounts for the largest share of the total expense of green hydrogen (~80 %). The decline of electricity and electrolyser prices are key in driving down the overall costs. In addition, by-product oxygen is also considered in the model to assess its economic benefits. We found that by-product oxygen sales could partly reduce the total expense of green hydrogen (~12 % at a price of USD 85/t), but it also should be noted that the volatile price of oxygen may pose uncertainties and risks to the effectiveness of the offset. Since the case study may represent the favourable conditions in China due to the abundant renewable energy resources and large-scale ammonia industry in this region, we propose to take a moderate step towards green ammonia production, and policies should be focused on reducing the electricity price and capital investments in green hydrogen production. We assume the findings and implications are informative to planning future green ammonia production in China.     

Techno-economic analysis of hydropower based green ammonia plant for urea production in Nepal

This study presents a detailed design, economic, sensitivity and uncertainty analysis for establishing a hydropower based green ammonia plant for use in urea manufacturing in the context of Nepal. The electrolyzer plant for producing hydrogen was simulated with the help of DWSIM while the air separation and ammonia synthesis units were simulated with the help of Aspen Plus for producing 1245 ton/day of ammonia to meet the annual urea demand of Nepal. The capitalized cost of the electrolyzer, air separation and the ammonia synthesis unit of this size were calculated to be 26 million, 7 million and 9 million USD/year respectively. The levelized cost of hydrogen (H₂) and ammonia (NH₃) were found to be 3602 and 826 USD/ton respectively. Economic profitability analysis showed profitability of the plant with ROI and IRR of 38% and 26% respectively with a payback period of three years after operation. The sensitivity analysis showed strong sensitivity on the utility (electricity) cost for both the electrolyzer and ammonia synthesis unit which presents a strong opportunity for Nepal. The levelized cost for H₂ and NH₃ varied between 2845 USD/ton and 4361 USD/ton and 634 USD/ton and 1018 USD/ton respectively for ±30% variation in the utility (electricity) cost. Uncertainty analysis using Monte Carlo method showed the possible minimum levelized cost of H₂ and NH₃ to be 2340 USD/ton and 418 USD/ton respectively. This study illustrates the potential of hydropower based ammonia synthesis for urea manufacturing and provides an important baseline value for policymakers to make investment decisions and to formulate policies for this pathway of production.     

Power to gas: addressing renewable curtailment by converting to hydrogen

Renewable energy is the key to meeting increasing electricity demand and the decarburization targets in the generation mix. However, due to constrained power network capacity, a large volume of renewable generation is curtailed particularly from wind power, which is a huge waste of resources. There are typically three approaches to addressing excessive renewable: direct curtailment, the reinforcement of networks to expand transfer capacity, and the conversion of excessive renewable into other energy types, such as hydrogen, to transport. The costs and benefits of the three approaches could vary significantly across location, time, and penetration of renewable energy. This paper conducts a cost-benefit analysis and comparison of the three techniques to address wind curtailment. It uses a reduced 16-busbar UK transmission network to analyze the performance of the three approaches. The UK 2020 generation mix is used to quantify the saved renewable energy and incurred costs. The payback time and net present value of the two investment techniques are compared. From demonstration, it is reasonable to conclude that converting excessive wind power into hydrogen to transport is an environmentally friendly and cost-effective way to address wind curtailment.     

Opportunities for green hydrogen production in petroleum refining and ammonia synthesis industries in India

Increasing penetration of renewable electricity in the power systems coupled with reduction in its cost has resulted in increased interest in green hydrogen globally. Industry has been using fossil fuel-based hydrogen as an input for several decades. This paper makes an assessment of existing hydrogen production capacities in petroleum refineries and ammonia synthesis units in India along with estimating the potential for installing solar photovoltaic (SPV) powered alkaline electrolysers for producing green hydrogen and SPV capacity required for this purpose. Levelised cost of hydrogen production in these industries in India has been analysed and found to be competitive. The paper also discusses about water requirement, land requirement for SPV power plants, CO₂ emissions avoided and likely investment to be made for establishing infrastructure for green hydrogen production. With launching of national hydrogen mission in India, a transition to green hydrogen by the industry appears to be a near term possibility.     

Estimating global production and supply costs for green hydrogen and hydrogen-based green energy commodities

Green energy commodities are expected to be central in decarbonising the global energy system. Such green energy commodities could be hydrogen or other hydrogen-based energy commodities produced from renewable energy sources (RES) such as solar or wind energy. We quantify the production cost and potentials of hydrogen and hydrogen-based energy commodities ammonia, methane, methanol, gasoline, diesel and kerosene in 113 countries. Moreover, we evaluate total supply costs to Germany, considering both pipeline-based and maritime transport. We determine production costs by optimising the investment and operation of commodity production from dedicated RES based on country-level RES potentials and country-specific weighted average costs of capital. Analysing the geographic distribution of production and supply costs, we find that production costs dominate the supply cost composition for liquid or easily liquefiable commodities, while transport costs dominate for gaseous commodities. In the case of Germany, importing green ammonia could be more cost-efficient than domestic production from locally produced or imported hydrogen. Green ammonia could be supplied to Germany from many regions worldwide at below the cost of domestic production, with costs ranging from 624 to 874 $/t NH₃ and Norway being the cheapest supplier. Ammonia production using imported hydrogen from Spain could be cost-effective if a pan-European hydrogen pipeline grid based on repurposed natural gas pipelines exists.     

Flexible production of green hydrogen and ammonia from variable solar and wind energy: Case study of Chile and Argentina

We report a techno-economic modelling for the flexible production of hydrogen and ammonia from water and optimally combined solar and wind energy. We use hourly data in four locations with world-class solar in the Atacama desert and wind in Patagonia steppes. We find that hybridization of wind and solar can reduce hydrogen production costs by a few percents, when the effect of increasing the load factor on the electrolyser overweighs the electricity cost increase. For ammonia production, the gains by hybridization can be substantially larger, because it reduces the power variability, which is costly, due to the need for intermediate storage of hydrogen between the flexible electrolyser and the less flexible ammonia synthesis unit. Our modelling reveals the crucial role in the synthesis of flexibility, which cuts the cost of variability, especially for the more variable wind power. Our estimated near-term production costs for green hydrogen, around 2 USD/kg, and green ammonia, below 500 USD/t, are encouragingly close to competitiveness against fossil-fuel alternatives.     

Evaluation of strategic directions for supply and demand of green hydrogen in South Korea

Currently, worldwide efforts are being made to replace fossil fuels with renewable energy to meet the goals of the Paris Agreement signed in 2015. Renewable energy, with solar and wind power as representative examples, focuses on hydrogen as a means of supplementing the intermittency in operation. Moreover, 17 advanced countries, including Australia and Europe, announced policies related to hydrogen, and Korea joined the ranks by announcing a roadmap to revitalize the hydrogen economy in 2019. As of 2020, the unit price of renewable energy in Korea is 0.1 $/kWh and 0.12 $/kWh for solar and wind power, respectively, which are more than five times higher than those of the world's best. The significant difference is due to the low utilization of power plants stemming from environmental factors. Consequently, securing the economic feasibility for the production of green hydrogen in Korea is difficult, and the evaluation of various policies is required to overcome these shortcomings. Currently, Korea's policy on renewable energy is focused on solar power, and despite the goal for a power generation of 57,483 GWh/year centered on offshore wind power by 2034, plans for utilization are lacking. By harnessing such energy, producing a percentage of the total green hydrogen required from the hydrogen economy roadmap can be realized, but securing economic feasibility may be difficult. Therefore, reinforcements in policies for the production of green hydrogen in Korea are required, and implementation of foreign policies for overseas cooperation in hydrogen production and import is necessary.     

Exploring the future of 2D catalysts for clean and sustainable hydrogen production

To address climate variations and the world's energy dilemma, hydrogen is an eco-friendly and sustainable energy carrier that may substitute for fossil fuel. A vast quantity of energy may be delivered or stored using hydrogen as a carrier. The prevailing hydrogen production mainly depends on fossil fuels making them one of today's most commonly used commodities. The Paris Agreement has been approved by 194 Parties as of right now (193 States plus the European Union) which pledged to achieve zero emissions targets as a response to the climate change threat on a global scale. Increasing the generation of green hydrogen from renewable sources of energy will help to provide little to no danger to the environment. Numerous techniques, such as photolysis, thermolysis, and electrolysis, can be used to synthesize sustainable hydrogen. Catalyst use can boost efficiency, whereas 2D catalysts can bring more efficiency in the production of green hydrogen that helps to minimize carbon dioxide emissions in the environment which is harmful to both environment and humans. The size of the worldwide green hydrogen marketing is anticipated to be USD 2565.7 million in 2028, growing at a 14% Compounded annual growth rate (CAGR) in terms of revenue. The primary topic covered in this review is the catalytic activity of 2D materials that may be utilized to create green hydrogen and increase manufacturing efficiency. A correlative study has been carried out through this article on the 2D catalysts such as MXene, graphene, and MOFs, of which graphene was found to be most effective in the production of hydrogen.     

Willingness to pay for green electricity in Korea: A contingent valuation study

Green electricity is energy that is generated from renewable energy sources such as solar power, wind power, small-scale hydroelectric power, tidal power, and biomass power. These sources mostly do not produce pollutants and are considered environmentally friendly. However, considering the current state of technology, they are more costly. Government should take visible actions to compensate for the increased production costs. This paper attempts to apply a contingent valuation (CV) method to obtain at least a preliminary evaluation of the benefits that ensue from the introduction of the policy that raises the percentage of green electricity consumption from 0.2% of the total electricity supply to 7% by 2011. Overall, the CV survey was successful in eliciting the willingness to pay (WTP) for green electricity considering that the CV method operated within respondents’ abilities to answer and the WTP estimates were statistically significant. The monthly mean WTP estimates from parametric and non-parametric methods were KRW 1681 (USD 1.8) and KRW 2072 (USD 2.2), respectively. The estimates of the annual benefits to relevant residents amounted to KRW 150.5 billion (USD 157.5 million) and KRW 185.6 billion (USD 194.2 million), respectively.     

Electrolysers for mitigating wind curtailment and producing ‘green’ merchant hydrogen

The implementation electrolysis plant in combination with wind power plant is proposed, to absorb wind generation otherwise curtailed while generating ‘green’ hydrogen for the merchant hydrogen market. The objective are to (i) achieve exceptionally high wind power penetrations in future power systems, and (ii) derive hydrogen for sale in the existing merchant industrial market from surplus (zero cost) renewable electricity. The economic rationale is investigated for an isolated power system as a function wind penetration, wind curtailment target, electrolyser cost, hydrogen system efficiency and hydrogen sales price. The main outputs are the total annualized cost of wind power plant with electrolysis plant, net annual revenues and discounted pay-back periods. Unprecedented low values of pay-back period are attainable, relative to the implementation of wind power plant at low wind penetrations (Φ_W). For example, at Φ_W = 50%, a wind curtailment target of 80% allows the investment to be recovered after 4-7 years, provided the hydrogen system efficiency is ≥50% and the hydrogen sales price is 20-30 $/kg. Making use of some non-curtailed wind electricity to boost the utilization of the electrolyser stock is also investigated as a means for improving the return on investment.     

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.     

Green hydrogen-based pathways and alternatives: Towards the renewable energy transition in South America's regions–Part B

Hydropower compounds most of the energy matrix of the countries of the Latin America and Caribbean region (LAC). Considering the concern in reducing Green House Gases emissions (GHG) from hydropower plants and hydrogen production from fossil sources, green hydrogen (H₂) appears as an energy vector able to mitigate this impact. Improving the efficiency of the plant and producing renewable energy the element is an interesting alternative from the ecological and economic point of view. This study aims to estimate the potential of H₂ production from wasted energy, through the electrolysis of water in hydroelectric plants in Colombia and Venezuela. The construction of two scenarios allowed obtaining a difference, considering a spilled flow of 2/3 in the first scenario and 1/3 in the second. In Colombia, hydrogen production reached 3.39 E+08 Nm³ at a cost of 2.05 E+05 USD/kWh in scenario1, and 1.70 E+08 Nm³ costing 4.10 E+05 USD/kWh in scenario 2. Regarding the Venezuelan context, the country obtained lower production values of H₂, ranging between 7.76 E+07 Nm³.d^?1 and 4.31 E+07 Nm³.d^?1, and production cost between 9.45 E+09 USD/kWh and 1.89 E+10 USD/kWh. Thus, the final cost for the production and storage of H₂ was estimated at 0.2239 USD.kg^?1. Ultimately, Colombia and Venezuela have a large potential to supply the demand for nitrogen fertilizers with green ammonia production, apply green hydrogen in manufacturing and use the surplus for energy substitution of Liquefied Petroleum Gas - LPG. In Colombia, the chemical energy offered is equivalent to 6.681 E+11 MJ/year^?1 and in Venezuela, the result is equal to 1.697 E+11 MJ/year^?1 in the conservative scenario. Finally, the countries have great potential for the diversification of the energy matrix and the insertion of renewables in the system.     

Economic and climate impacts of reducing China's renewable electricity curtailment: A comparison between CGE models with alternative nesting structures of electricity

To mitigate climate change impacts and achieve low-carbon transformation, China has accelerated the development of renewable energy, which is severely challenged by the curtailment of renewable electricity. This study uses a dynamic multi-sectoral CGE model with alternative nesting structures and substitution elasticities for electricity with different power sources to capture the economic and environmental feasibility of reducing renewable electricity curtailment across all economic sectors in China. The reduction of renewable electricity curtailment is simulated during 2021–2030 from the curtailment rates of 2015–2017. We found that the reduction of renewable electricity curtailment would lead to a significant expansion in the output of renewable electricity and a moderate decrease in non-renewable electricity production. Among the renewable electricity, wind power has the most significant output gain (over 9%), with solar power and hydropower outputs rising by over 5% and 1.5%, respectively. However, without the cost-neutrality assumption, the impacts of reducing electricity curtailment would be largely over-estimated with CGE models simulated by improved technology. The disparity between results from the models with alternative nesting constant elasticity of substitution (CES) functions for electricity sectors is highly dependent on the difference between their substitution elasticities. Accompanying the changes in electricity generation, the reduction of renewable electricity curtailment would bring multiple green co-benefits like significantly reducing CO2 and air pollutants emitted from electricity sectors, and improvements in real GDP and employment.     

Green hydrogen for heating and its impact on the power system

With a relatively high energy density, hydrogen is attracting increasing attention in research, commercial and political spheres, specifically as a fuel for residential heating, which is proving to be a difficult sector to decarbonise in some circumstances. Hydrogen production is dependent on the power system so any scale use of hydrogen for residential heating will impact various aspects of the power system, including electricity prices and renewable generation curtailment (i.e. wind, solar). Using a linearised optimal power flow model and the power infrastructure on the island of Ireland this paper examines least cost optimal investment in electrolysers in the presence of Ireland's 70% renewable electricity target by 2030. The introduction of electrolysers in the power system leads to an increase in emissions from power generation, which is inconsistent with some definitions of green hydrogen. Electricity prices are marginally higher with electrolysers whereas the optimal location of electrolysers is driven by a combination of residential heating demand and potential surplus power supplies at electricity nodes.     

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.     

中国规模化氢能供应链的经济性分析

    目的   文章研究规模化氢能供应链的经济性,未来十年,氢能作为战略能源将会重构社会的能源结构,并影响未来社会能源总成本。预测大规模氢能时代的制氢、储氢、输氢、分销、应用的成本,和市场化的趋势有着重要的意义。氢气由于高储运成本,用途、品质的多样性,氢气市场存在分层结构。分析氢能与常规能源的可比价格,提出原油当量价格(POE)的概念,预测未来氢能价格的合理区间。解决供应链问题是获得低成本氢能的关键,由此提出干线门站模式,解决绿氢的资源分布与长距离输送氢能的问题。    方法   利用平准化氢气成本(LCOH)分析模型,测算大型光伏制氢管道输氢LCOH,分析大规模可再生能源制氢输氢的经济性。利用氢能供应链的储、输、卸六个象限成本公式,分析气氢、液氢、固氢、有机氢、管道氢等不同储运技术,短距离氢储运成本,分析门站后输氢的场景和成本,预测短距离输氢的成本趋势。    结果   研究表明:我国有丰富的绿氢资源,随着投资下降,预计大规模绿氢管道输送的城市门站LCOH将低于2.0 RMB/Nm3,将成为未来主要的氢源。当前,氢储运技术气氢、液氢、甲醇、合成氨、有机氢、固氢、管道氢,随着规模的增加实现远距离输送。在现有的技术下,城市门站到终端的输送,氢短距输送（<100 km）测算成本都在1.2 RMB/Nm3以下,由此评估的氢能供应链的总成本,干线门站模式下氢能最终到达终端的价格约为3.2 RMB/Nm3,当量价格POE与汽油价格接近,考虑燃料电池的能效因素,氢能汽车在4.0 RMB/Nm3的氢价下,具有比汽油车更低的百公里燃料费用。    结论   因此,氢能作为战略能源,在无补贴的情况下实现中国氢能源的绿氢替代,在技术经济上是可行的。     

Integrated planning method of green hydrogen supply chain for hydrogen fuel cell vehicles

To satisfy the growing refueling demand of hydrogen fuel cell vehicles (HFCVs) with carbon-free hydrogen supply, this paper proposes an integrated planning method of green hydrogen supply chain. First, the k-shorted path method is introduced to analyze HFCV refueling load considering vehicle travel habits and routing diversity. Second, based on it, a two-stage integrated planning model is established to minimize the total investment and operation cost. The construction of hydrogen refueling stations, electrolysis-based hydrogen generation stations and hydrogen pipelines are coordinated with their operating constraints, constituting the green hydrogen supply chain, in which hydrogen storage is also an important part for consideration to address variable renewable power. Then, the proposed model is reformulated as a mixed integer linear programing (MILP) problem solved efficiently. Finally, the case studies are carried out on an urban area in Xi'an China to verify the validity and correctness of the proposed method. The results show that the integrated planning can realize synergy benefits. The influence of electricity prices and k values is also discussed.     

Cost effects of international trade in meeting EU renewable electricity targets

The European market for renewable electricity received a major stimulus from the adoption of the Directive on the Promotion of Renewable Electricity. The Directive specifies the indicative targets for electricity supply from renewable energy sources (RES-E) to be reached in European Union (EU) Member States in the year 2010. It also requires Member States to certify the origin of their renewable electricity production. This article presents a first EU-wide quantitative evaluation of the effects of meeting the targets, using an EU-wide system for tradable green certificates (TGC). We calculate the equilibrium price of green certificates and identify which countries are likely to export or import certificates. Cost advantages of participating in such an EU-wide trading scheme are determined for each of the Member States. Moreover, we identify which choice of technologies results in meeting targets at least costs. Results are obtained from a model that quantifies the effects of achieving the RES-E targets in the EU with and without trade. The article provides a brief insight in this model as well as the methodology that was used to specify cost potential curves for renewable electricity in each of the 15 EU Member States. Model calculations show that within the EU-wide TGC system, the total production costs of the last option needed to satisfy the overall EU RES-E target equals 9.2 eurocent/kWh. Assuming that the production price of electricity on the European power market would equal 3 eurocent/kWh in the year 2010, the indicative green certificate price equals 6.2 eurocent/kWh. We conclude that implementation of an EU-wide TGC system is a cost-efficient way of stimulating renewable electricity supply.     

Prospects and economic feasibility analysis of wind and solar photovoltaic hybrid systems for hydrogen production and storage: A case study of the Brazilian electric power sector

The work aims to verify the economic feasibility of renewable hybrid systems for hydrogen production and storage in the Brazilian electric power sector. The methodology applied is based on economic cost analyses of the two largest wind and solar photovoltaic plants in the country. As a result, the number of hours of electricity available for hydrogen production directly influences its cost. However, fully dedicated plants to produce green hydrogen have shown economically feasible to the exporter or other sectors, being trading hydrogen is more profitable than transforming it back into power. The model also concludes that wind and solar hybrid systems for hydrogen production and storage are still not economically viable in Brazil. The CAPEX of electrolysers and their operating losses are still very significant. Finally, hydrogen production and storage become economically feasible only from plants operating above 3000 h and for electrolysers with a CAPEX of USD 650/kWe.     

Techno-economic calculation of green hydrogen production and export from Colombia

In the present paper a techno-economic hydrogen production and transportation costs to export from Colombia to Europe and Asia were determined using the open-source Python tools, such as WindPowerLIB, PVLIB, ERA5 weather data, and the Hydrogen-2-Central (H2C) model. Calculations were performed as well for Chile, for comparison as a regional competitor. In addition, a detailed overview of Colombia's energy system and national efforts for a market ramp-up of renewable energy and hydrogen is provided. The application of the model in different scenarios shows Colombia's potential to produce green hydrogen using renewable energies. The prices estimated are 1.5 and 1.02 USD/kgH₂ for 2030 and 2050 with wind power, and 3.24 and 1.65 USD/kgH₂ for 2030 and 2050 using solar energy. Colombia can become one of the most promising hydrogen suppliers to Asian and European countries with one of the lowest prices in the production and transportation of green hydrogen.