Sustainability of hydrogen refuelling stations for trains using electrolysers

Hydrogen has the potential to become a powerful energy vector with different applications in many sectors (industrial, residential, transportation and other applications) as it offers a clean, sustainable, and flexible alternative. Hydrogen trains use compressed hydrogen as fuel to generate electricity using a hybrid system (combining fuel cell and batteries) to power traction motors and auxiliaries. This hydrogen trains are fuelled with hydrogen at the central train depot, like diesel locomotives. The main goal of this paper is to perform a techno-economic analysis for a hydrogen refuelling stations using on-site production, based on PEM electrolyser technology in order to supply hydrogen to a 20 hydrogen-powered trains captive fleet. A sensitivity analysis on the main parameters will be performed as well, in order to acquire the knowledge required to take any decisions on implementation regarding electricity cost, hydrogen selling price, number of operation hours and number of trains for the captive fleet.The main methodology considers the evaluation of the project based on the Net Present Value calculation and the sensitivity analysis through standard method using Oracle Crystal Ball. The main result shows that the use of hydrogen as an alternative fuel for trains is a sustainable and profitable solution from the economic, environmental and safety points of view.The economic analysis concludes with the need to negotiate an electricity cost lower than 50 €/MWh, in order to be able to establish the hydrogen selling price at a rate higher than 4.5€/kg. The number of operating hours should be higher than 4800 h per year, and the electrolyser system capacity (or hydrogen refuelling station capacity) should be greater than 3.5 MW in order to reach a Net Present Value of 7,115,391 € with a Return of Investment set to 9 years. The result of the multiparametric sensitivity analysis for the Net Present Value (NPV) shows an 85.6% certainty that the project will have a positive result (i.e. profitability) (NPV> 0). The two main variables with the largest impact on Net Present Value are the electrolyser capacity (or hydrogen refuelling station capacity) and the hydrogen selling price. Moreover, a margin of improvement (higher NPV) could be reached with the monetization of the heat, oxygen by-product and CO₂ emission reduction.     

Parameter study for dimensioning of a PV optimized hydrogen supply plant

Green hydrogen produced from intermittent renewable energy sources is a key component on the way to a carbon neutral planet. In order to achieve the most sustainable, efficient and cost-effective solutions, it is necessary to match the dimensioning of the renewable energy source, the capacity of the hydrogen production and the size of the hydrogen storage to the hydrogen demand of the application.For optimized dimensioning of a PV powered hydrogen production system, fulfilling a specific hydrogen demand, a detailed plant simulation model has been developed. In this study the model was used to conduct a parameter study to optimize a plant that should serve 5 hydrogen fuel cell buses with a daily hydrogen demand of 90 kg overall with photovoltaics (PV) as renewable energy source. Furthermore, the influence of the parameters PV system size, electrolyser capacity and hydrogen storage size on the hydrogen production costs and other key indicators is investigated. The plant primarily uses the PV produced energy but can also use grid energy for production.The results show that the most cost-efficient design primarily depends on the grid electricity price that is available to supplement the PV system if necessary. Higher grid electricity prices make it economically sensible to invest into higher hydrogen production and storage capacity. For a grid electricity price of 200 €/MWh the most cost-efficient design was found to be a plant with a 2000 kWp PV system, an electrolyser with 360 kW capacity and a hydrogen storage of 575 kg.     

A multivariate coupled economic model study on hydrogen production by renewable energy combined with off-peak electricity

An economic prediction model of hydrogen production from renewable energy complemented with off-peak electricity is developed, and the cost of carbon emission for the off-peak electricity from grid is also considered. The variation of hydrogen cost with the utilization hours of off-peak electricity and the allowable range of off-peak electricity utilization hours under different carbon prices and grid average emission factors are investigated. The results show that it is influenced by the multiplication product of the carbon price and the average carbon emission factor of the grid electricity. The use of off-peak electricity reduces the cost of hydrogen when the multiplication product is less than a critical value, while it causes an increase in the cost of hydrogen when larger than the critical value. Off-peak electricity utilization hours are also constrained by the emission intensity requirement of low-carbon or clean hydrogen. In addition, a generalized multivariate coupled analysis method is developed by investigating single variable sensitivities and decision needs at different stages of the project. The results show that the key coupling variables in the site selection stage are hydrogen price, renewable energy utilization hours and integrated tariff, which is determined by both renewable energy and off-peak grid electricity. In the scheme design stage the key coupling variables are electrolysis energy consumption and unit installed cost. When project parameters are determined along with site specific hydrogen price and renewable energy tariffs, further scheme optimization can be undertaken.     

Exergetic analysis of hydrogen utilisation pathways – Part 1: Energy supply in buildings

This article analyses exergy losses along hydrogen utilisation pathways recently discussed in Germany and other countries. As a renewable fuel hydrogen will be an important part of sustainable future economies. Hydrogen can be used in all sectors, especially in buildings, for mobility and in industry, e.g. in steel production or ammonia synthesis. However, hydrogen has to be produced in a sustainable way. The most promising production is via water electrolysis using renewable electricity. In the first part of this work, exergy analysis is made for the complete hydrogen pathways from production until final utilisation for energy supply in buildings. The second part will focus on pathways for mobility. In the third part, the results are compared with available alternatives to hydrogen such as direct use of electricity in building supply or mobility. The results for building energy supply show that firstly transportation in pipelines (mixture with natural gas and pure hydrogen) is very efficient. Secondly, major exergy losses are caused by the electrolyser. Thirdly, combustion of renewable hydrogen for room heating in common boilers cause the highest exergy losses, but the use of combined heat and power (CHP) units or fuel cells can improve the exergy efficiency substantially.     

Dynamic production,storage, and use of renewable hydrogen: A technical-economic-environmental analysis in the public transport system in São Paulo state,Brazil

This article proposes a calculation methodology that starts from the demand calculation to supply a fleet bus with renewable hydrogen based on the electrolysis process until the energetic, economic, and environmental analyses, involving all the processes of the productive chair. Also considering the dynamic behaviour of the following hydrogen processes: production, storage, and use. The simplified scheme of the proposed system configuration to be studied consists of the use of alternative and renewable sources of energy (solar-wind-biogas) to generate electrical energy in order to produce hydrogen from electrolysis of the water, which is stored in its gaseous state and subsequently redirected to a filling station to be used as vehicle fuel in buses. The results show that to feed one bus the hybrid system generates an average of 78,110 kWh/month with an installed capacity of 1101.905 kW, producing 1209.90 kgH₂/month through the electrolysis process from water. The results also show a range of electricity generation costs between 1.130 and 0.123 US$/kWh and H₂ production between 0.963 and 0.110 US$/kWh. Concluding that the application of renewable energies to produce hydrogen and electricity for the public transport sector is an attractive alternative in the future throughout the country, because the proposed system is technically, economically and ecologically viable.     

The production of electricity,heat and hydrogen with the thermal power plant in combination with alternative technologies

Alternative technologies in combination with thermal power plant allow the production of heat, electricity and hydrogen using renewable energy sources in combination with gas or coal, as a very important energy source in traditional energy engineering in Slovenia. The technologies aim, inter alia, to reduce greenhouse gas emissions, increase the use of renewable energy sources and take a step forward to the production of hydrogen as an alternative energy source in numerous applications. In view of the estimated demand for heat, electricity and hydrogen in the Savinja-?alek region, Slovenia, the technologies to meet such demand are proposed in this article from a technical perspective. An energy and economic analysis of the operation of the Thermal Power Plant (TPP) will be done. The TPP is operating in a variable operating regime. The possibility of stationary operation of the power plant will be analysed, the surplus of produced electricity will be used for the hydrogen production. The process is based on the Rankine-Clausius cycle (RC) with dual superheating using water or steam as the working media. The idea in this article, is to generate in the above mentioned facility as much hydrogen, heat, cold and electricity as needed by the Savinja-?alek region in industry, transport, etc. Thus, the power plant could operate optimally, constantly at 100% of power, which would allow simultaneous production of electricity, heat and hydrogen. Hydrogen could be used for sale on the market or for the electricity production or for heating. Hydrogen could be produced via electrolysis or thermochemical process. In the second part of article, the analysis of RC with concentrated solar energy and wood chips was analysed.     

Operation of solid oxide fuel cells with alternative hydrogen carriers

Future electricity production will use fossil-free sources with zero CO₂ emission or closed carbon cycle technologies based on renewable sources. While hydrogen is considered a key energy source, its production at present time relies heavily on fossil fuels. Furthermore, distribution and storage are not well established and require substantial investments. This is a strong motivation to identify alternative, safe, high power density hydrogen carriers, where existing logistics and infrastructure can be utilized. In this contribution, ammonia and biogas are considered for high-efficient electricity production in solid oxide fuel cells (SOFCs). It is demonstrated that the properties and operating conditions of SOFC allow for direct use of these fuels, with fuel pretreatment inside the SOFC anode. The high efficient electricity production using pure ammonia or real biogas was successfully proven on state-of-the-art SOFCs. Even without optimization of operating parameters, electrical efficiencies of 40–50% and high and stable power output were demonstrated.     

Exergoeconomic machine-learning method of integrating a thermochemical Cu–Cl cycle in a multigeneration combined cycle gas turbine for hydrogen production

Integrating new technologies into existing thermal energy systems enables multigenerational production of energy sources with high efficiency. The advantages of multigenerational energy production are reflected in the rapid responsiveness of the adaptation of energy source production to current market conditions. To further increase the useful efficiency of multigeneration energy sources production, we developed an exergoeconomic machine-learning model of the integration of the hydrogen thermochemical Cu–Cl cycle into an existing gas-steam power plant. The hydrogen produced will be stored in tanks and consumed when the market price is favourable. The results of the exergoeconomic machine-learning model show that the production and use of hydrogen, in combination with fuel cells, are expedient for the provision of tertiary services in the electricity system. In the event of a breakdown of the electricity system, hydrogen and fuel cells could be used to produce electricity for use by the thermal power plant. The advantages of own or independent production of electricity are primarily reflected in the start-up of a gas-steam power plant, as it is not possible to start a gas turbine without external electricity. The exergy analysis is also in favour of this, as the integration of the hydrogen thermochemical Cu–Cl cycle into the existing gas-steam power plant increases the exergy efficiency of the process.     

Technical and economical design of PV system and hydrogen storage including a sodium hypochlorite plant in a small community: Case of study of Paraguay

The increasing use of renewable power sources for distributed generation (DG) has made the application of storage systems a necessity to ensure the continuous supply. This paper analyzes technically and economically an autonomous sodium hypochlorite plant using a renewable energy source and a hydrogen storage system in the Western Region of Paraguay. In this region, there is abundant underground brackish water to produce industrial and energetic hydrogen. In addition, an isolated photovoltaic (PV) system feeds with electricity an electrolyzer, used for sodium hypochlorite production, and the brackish water and freshwater pumping systems. The hydrogen and fuel cell are used as backup system in the operation of the electrolyzer. Preliminary results show that hydrogen stored during the day can increase hypochlorite production by up to 31%. The PV solar system surplus can supply the demand of an off-grid community near the plant. The results show that the plant's return on investment (ROI) is 7 years.     

Hydrogen as a long-term,large-scale energy storage solution when coupled with renewable energy sources or grids with dynamic electricity pricing schemes

One of the key challenges that still facing the adoption of renewable energy systems is having a powerful energy storage system (ESS) that can store energy at peak production periods and return it back when the demand exceeds the supply. In this paper, we discuss the costs associated with storing excess energy from power grids in the form of hydrogen using proton exchange membrane (PEM) reversible fuel cells (RFC). The PEM-RFC system is designed to have dual functions: (1) to use electricity from the wholesale electricity market when the wholesale price reaches low competitive values, use it to produce hydrogen and then convert it back to electricity when the prices are competitive, and (2) to produce hydrogen at low costs to be used in other applications such as a fuel for fuel cell electric vehicles. The main goal of the model is to minimize the levelized cost of energy storage (LCOS), thus the LCOS is used as the key measure for evaluating this economic point. LCOS in many regions in United States can reach competitive costs, for example lowest LCOS can reach 16.4¢/kWh in Illinois (MISO trading hub) when the threshold wholesale electricity price is set at $25/MWh, and 19.9¢/kWh in Texas (ERCOT trading hub) at threshold price of $20/MWh. Similarly, the levelized cost of hydrogen production shows that hydrogen can be produced at very competitive costs, for example the levelized cost of hydrogen production can reach $2.54/kg-H₂ when using electricity from MISO hub. This value is close to the target set by the U.S. Department of Energy.     

Energy system aspects of hydrogen as an alternative fuel in transport

Considering the enormous ecological and economic importance of the transport sector the introduction of alternative fuels—together with drastic energy efficiency gains—will be a key to sustainable mobility, nationally as well as globally. However, the future role of alternative fuels cannot be examined from the isolated perspective of the transport sector. Interactions with the energy system as a whole have to be taken into account. This holds both for the issue of availability of energy sources as well as for allocation effects, resulting from the shift of renewable energy from the stationary sector to mobile applications. With emphasis on hydrogen as a transport fuel for private passenger cars, this paper discusses the energy systems impacts of various scenarios introducing hydrogen fueled vehicles in Germany. It identifies clear restrictions to an enhanced growth of clean hydrogen production from renewable energy sources (RES). Furthermore, it points at systems interdependencies that call for a priority use of RES electricity in stationary applications. Whereas hydrogen can play an increasing role in transport after 2030 the most important challenge is to exploit short–mid-term potentials of boosting car efficiency.     

Hydrogen and power co-generation based on coal and biomass/solid wastes co-gasification with carbon capture and storage

This paper investigates the potential use of renewable energy sources (various sorts of biomass) and solid wastes (municipal wastes, sewage sludge, meat and bone meal etc.) in a co-gasification process with coal to co-generate hydrogen and electricity with carbon capture and storage (CCS). The paper underlines one of the main advantages of gasification technology, namely the possibility to process lower grade fuels (lower grade coals, renewable energy sources, solid wastes etc.), which are more widely available than the high grade coals normally used in normal power plants, this fact contributing to the improvement of energy security supply. Based on a proposed plant concept that generates 400–500 MW net electricity with a flexible output of 0–200 MW_th hydrogen and a carbon capture rate of at least 90%, the paper develops fuel selection criteria for coal blending with various alternative fuels for optimizing plant performance e.g. oxygen consumption, cold gas efficiency, hydrogen production and overall energy efficiency. The key plant performance indicators were calculated for a number of case studies through process flow simulations (ChemCAD).     

Costs and benefits of the renewable production of electricity in Spain

The reduction of pollutant emissions and greenhouse gases, as well as the strong energy dependence on fossil fuels (gas and fuel oil), have, among other reasons, led many countries in recent years to develop policies to promote and encourage the use of alternative, sustainable, clean and predictable sources of energy. This paper presents an overview of the production of electricity from renewable sources (PE-RES) in Spain, and offers an outline of the current level of development of renewable energy. It also reviews the current support system, the costs of integrating renewable energy into the electric system as well as the effects of this type of energy on the electricity wholesale market price, the Gross Domestic Product (GDP), the environment, human health and employment.     

The economic feasibility study of a 100-MW Power-to-Gas plant

Power-to-Gas (PtG) is a grid-scale energy storage technology by which electricity is converted into gas fuel as an energy carrier. PtG utilizes surplus renewable electricity to generate hydrogen from Solid-Oxide-Cell, and the hydrogen is then combined with CO₂ in the Sabatier process to produce the methane. The transportation of methane is mature and energy-efficient within the existing natural gas pipeline or town gas network. Additionally, it is ideal to make use of the reverse function of SOC, the Solid-Oxide-Fuel-Cell, to generate electricity when the grid is weak in power. This study estimated the cost of building a hypothetical 100-MW PtG power plant with energy storage and power generation capabilities. The emphasis is on the effects of SOC cost, fuel cost and capacity factor to the Levelized Cost of Energy of the PtG plant. The net present value of the plant is analyzed to estimate the lowest affordable contract price to secure a positive present value. Besides, the plant payback period and CO₂ emission are estimated.     

Investigation of biomass gasification hydrogen and electricity co-production with carbon dioxide capture and storage

Biomass is one of the renewable energy resources which can be used instead of fossil fuels to diminish environment pollution and emission of greenhouse gases. Hydrogen as a biomass is considered as an alternative fuel which can be derived from a variety of domestically available primary sources. In this paper, a hydrogen and electricity co-generation plant with rice husk is proposed. Rice husk with water vapor and oxygen produces syngas in gasifier. In this design, electricity is generated by using two Rankine cycles. The Results show that the net electric efficiency and hydrogen production efficiency are 1.5% and 40.0%, respectively. Hydrogen production is 1.316 kg/s in case which carbon dioxide is gathered and stored. The electricity generation is 5.923 MW_e. The main propose of implementing Rankine cycle is to eliminate hydrogen combustion for generating electricity and to reduce NO_x production. Furthermore, three kinds of membranes are studied in this paper.     

Alternative carriers for remote renewable energy sources using existing CNG infrastructure

Optimal locations of renewable energy sources are often remote relative to consumers and electricity grids. In contrast, some existing CNG pipelines pass through optimal renewable energy harvesting regions. The growing interest in the possibility of using geothermal energy in central Australia has created a need to assess the economic, technical, and environmental viability of converting remote renewable energy to fuel for transport using existing CNG pipelines, and to compare this alternative with that required to construct new high-capacity electricity transmission lines. This assessment is reported, using first the conversion of electricity to hydrogen, and then conversion of the hydrogen to methane. The paper also compares the alternative of direct injection of hydrogen into existing CNG pipelines to create “hythane” (HCNG). An economic assessment showed that the relative capital and operating costs are sufficient make the alternative carrier prospect worthy of further consideration.     

Carbon black and hydrogen production process analysis

The adoption of new environmentally responsible technologies, as well as, energy efficiency improvements in equipment and processes help to reduce CO2 rate emission into the atmosphere, contributing in delaying the consequences of intensive use of fossil fuels. For more effective actions, it is necessary to make the transition from the fossil-based to the renewable source economy. In this context, hydrogen fuel has a special role as clean vector of energy. Hydrogen has the potential to be decisive in mitigating greenhouse gas emissions, but fossil fuels high profitability due to global energy dependency actually drives the global economy.While renewable energy sources are not worldwide fully established, new technologies should be developed and used for the recovery of energetic streams nowadays wasted, to decarbonize hydrocarbons and to improve systems efficiency creating a path that can help nations and industries in the needed energy economy transition. Hydrogen gas can be generated by various methods from different sources such as coal and water. Currently, almost all of the hydrogen production is for industrial purpose and comes from the Steam Reforming, while the use of hydrogen in fuel cells is only incipient.The article analysis the plasma pyrolysis of hydrocarbons as a decarbonization option to contribute as a step towards hydrogen economy. It presents the Carbon Black and Hydrogen Process (CB&H Process) as an alternative option for hydrogen generation at large scale facility, suitable for supplying large amounts of high-purity carbon in elemental form. CB&H Process refers to a plant with hydrogen thermal plasma reactor able to decompose Hydrocarbons (HC's) into Hydrogen (H2) and Carbon Black (CB), a cleaner technology than its competing processes, capable of generating two products with high added value. Considering the Brazilian context in which more than 80% of the generated electricity comes from renewable sources, the use of electricity as one of the inputs in the process does not compromise the objective of reducing greenhouse gas emissions. It is important to consider that the use of renewable energy to produce two products derived from fossil fuels in a clean way represents integration of technologies into a more efficient system and an arrangement that contributes to the transition from fossil fuels to renewables.The economic viability of the CB&H process as a hydrogen generation unit (centralized) for refining applications also depends on the cost of hydrogen production by competing processes. Steam Methane Reforming (SMR) is a widespread method that produces twice the amount of hydrogen generated by natural gas plasma pyrolysis, but it emits CO2 gas and consumes water, while CB&H process produces solid carbon. For this reason, the paper seeks the carbon production cost by plasma pyrolysis as a breakeven point for large-scale hydrogen generation without water consumption and carbon dioxide emissions.     

Reducing cycling costs in coal fired power plants through power to hydrogen

The increase of renewable share in the energy generation mix makes necessary to increase the flexibility of the electricity market. Thus, fossil fuel thermal power plants have to adapt their electricity production to compensate these fluctuations. Operation at partial load means a significant loss of efficiency and important reduction of incomes from electricity sales in the fossil power plant. Among the energy storage technologies proposed to overcome these problems, Power to Gas (PtG) allows for the massive storage of surplus electricity in form of hydrogen or synthetic natural gas. In this work, the integration of a Power to Gas system (50 MWe) with fossil fuel thermal power plants (500 MWe) is proposed to reduce the minimum complaint load and avoid shutdowns. This concept allows a continuous operation of power plants during periods with low demand, avoiding the penalty cost of shutdown. The operation of the hybrid system has been modelled to calculate efficiencies, hydrogen and electricity production as a function of the load of the fossil fuel power plant. Results show that the utilisation of PtG diminishes the specific cost of producing electricity between a 20% and 50%, depending on the framework considered (hot, warm and cold start-up). The main contribution is the reduction of the shutdown penalties rather than the incomes from the sale of the hydrogen. At the light of the obtained results, the hybrid system may be implemented to increase the cost-effectiveness of existing fossil fuel power plants while adapting the energy mix to high shares of variable renewable electricity sources.     

PEM electrolysis for production of hydrogen from renewable energy sources

PEM electrolysis is a viable alternative for generation of hydrogen from renewable energy sources. Several possible applications are discussed, including grid independent and grid assisted hydrogen generation, use of an electrolyzer for peak shaving, and integrated systems both grid connected and grid independent where electrolytically generated hydrogen is stored and then via fuel cell converted back to electricity when needed. Specific issues regarding the use of PEM electrolyzer in the renewable energy systems are addressed, such as sizing of electrolyzer, intermittent operation, output pressure, oxygen generation, water consumption and efficiency.     

Cost and benefit of renewable energy in the European Union

An assessment is made as to whether renewable energy use for electricity generation in the EU was beneficial throughout the cycle of high and low oil prices. Costs and benefits are calculated with the EU statistics for the period of low oil prices 1998–2002 and high oil prices 2003–2009. The share of renewable energy in electricity production was 21% of all energy resources in 2008, growing on average 5% a year during 2003–2008 compared to nil growth of the fossil fuels mix. Correlations show significant impacts of growing renewable energy use on changes in consumers' electricity prices during the high and rapidly increasing fossil fuel prices in the period 2005–2008. The growing use has contributed to price decrease in most countries that use more renewable energy and price increase in many countries that use little renewable energy. Costs and benefits are assessed through comparison between the observed consumers' electricity prices and simulated prices had they followed the costs of fossil fuel mix. A net benefit of 47 billion euro throughout the oil price cycle is attributable to the growing use of renewable energy, which is on average 8 billion euro a year. This net benefit is larger than the total public support for renewable energy. The net benefit would be larger had the EU anticipated high oil prices through more public support during low oil prices, as this would create productive capacity, but countries' interests increasingly differed. An anti-cyclic EU policy is recommended.