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.     

Prospects for hydrogen as a transport fuel

Early forecasts for hydrogen's role in transport usually proved over-optimistic, with several seeing hydrogen as an important transport fuel by year 2010 or even much earlier. Over the past century, vehicular passenger transport has experienced hypergrowth in terms of task, energy use and greenhouse gas emissions. For a variety of reasons, future decades may well see a significantly reduced global passenger transport task, as well as a widespread phasing-out of internal combustion engine vehicles, especially in cities. In contrast, the global freight transport task is unlikely to decline much, and could even grow, so that freight transport will dominate total transport energy use. Even if the world does finally respond seriously to climate change, likely policies will not favour hydrogen for private passenger vehicles for many decades. Nevertheless, hydrogen has clear superiority over electric vehicles for heavy freight transport. Given this advantage, it may be desirable to promote hydrogen for freight well before large amounts of renewable hydrogen are available from surplus intermittent renewable energy electricity.     

Impact of electric vehicles on a future renewable energy‐based power system in Europe with a focus on Germany

Electric mobility is expected to play a key role in the decarbonisation of the energy system. Continued development of battery electric vehicles is fundamental to achieving major reductions in the consumption of fossil fuels and of CO₂ emissions in the transport sector. Hydrogen can become an important complementary synthetic fuel providing electric vehicles with longer ranges. However, the environmental benefit of electric vehicles is significant only if their additional electricity consumption is covered by power production from renewable energy sources. Analysing the implications of different scenarios of electric vehicles and renewable power generation considering their spatial and temporal characteristics, we investigate possible effects of electric mobility on the future power system in Germany and Europe. The time horizon of the scenario study is 2050. The approach is based on power system modelling that includes interchange of electricity between European regions, which allows assessing long‐term structural effects in energy systems with over 80% of renewable power generation. The study exhibits strong potential of controlled charging and flexible hydrogen production infrastructure to avoid peak demand increases and to reduce the curtailment of renewable power resulting in reduced system operation, generation, and network expansion costs. A charging strategy that is optimised from a systems perspective avoids in our scenarios 3.5 to 4.5 GW of the residual peak load in Germany and leads to efficiency gains of 10% of the electricity demand of plug‐in electric vehicles compared with uncontrolled loading.     

Re-envisioning the role of hydrogen in a sustainable energy economy

This paper addresses the fundamental question of where hydrogen might fit into a global sustainable energy strategy for the 21st century that confronts the three-pronged challenge of irreversible climate change, uncertain oil supply, and rising pollution. We re-envision the role of hydrogen at national and international strategic levels, relying entirely on renewable energy and energy efficiency. It is suggested the time for an exclusive ‘hydrogen economy’ has passed, since electricity and batteries would be used extensively as well. Yet hydrogen would still play a crucial role: in road and rail vehicles requiring a range comparable to today’s petrol and diesel vehicles; in coastal and international shipping; in air transport; and for longer-term seasonal storage on electricity grids relying mainly on renewables. Hydrogen fuel cell vehicles are proposed where medium and long distance trips are required, with plug-in battery electric vehicles reserved for just short trips. A hierarchy of spatially-distributed hydrogen production, storage and distribution centers relying on local renewable energy sources and feedstocks would be created to limit the required hydrogen pipeline network to the main metropolitan areas and regions by complementary use of electricity as a major energy vector. Bulk hydrogen storage would provide the strategic energy reserve to guarantee national and global energy security in a world relying increasingly on renewable energy. It is recommended that this vision next be applied to specific countries by conducting detailed energy-economic-environmental modeling to quantify its net benefits.     

A probabilistic model for 1st stage dimensioning of renewable hydrogen transport micro-economies

The implementation of a hydrogen transport economy based on renewable energy sources is seen by many as the ultimate sustainable transport solution. However, dimensioning of hydrogen production systems is complex: renewable energy sources are stochastic in nature, requiring the collection of empirical datasets relating to weather patterns on a daily, seasonal and annual basis; and hydrogen production is characterised by sensitivity to operating conditions and diversity in the performance of the component parts.A probabilistic model is developed for dimensioning of hydrogen production systems that removes the reliance on the collection of empirical datasets and the requirement for detailed performance characterisation of component parts. The model utilises well known correlations and distribution modelling techniques to predict energy output from either a photovoltaic array or wind turbine and hence the number of fuel cell electric vehicles (FCEVs) that could be supported on an annual basis.The model was implemented in MatLab and simulation results were compared with existing empirical based studies. Through simulation, limitations of the model were investigated and discussed. It was shown that the model was able to predict the number of FCEVs supported to within 10% (solar pathway) and 22% (wind pathway) for those studies investigated. These results are in alignment with the intention of the model as a first stage tool for the dimensioning of renewable hydrogen energy transport micro-economies.     

Integrating private transport into renewable energy policy: The strategy of creating intelligent recharging grids for electric vehicles

A new business model for accelerating the introduction of electric vehicles into private transport systems involves the provision by an Electric Recharge Grid Operator (ERGO) of an intelligent rechargeable network in advance of the vehicles themselves. The ERGO business model creates a market for co-ordinated production and consumption of renewable energy. The innovative contribution of the model rests in its ability to combine two problems and thereby solve them in a fresh way. One problem derives from utilizing power grids with a substantial increase in renewable electric energy production (as witnessed in the Danish case with wind energy) and managing the resulting fluctuating supply efficiently. The other problem concerns finding ways to reduce CO₂ emissions in the transport sector. The ERGO business model effectively solves both problems, by transforming EVs into distributed storage devices for electricity, thus enabling a fresh approach to evening out of fluctuating and unpredictable energy sources, while drastically reducing greenhouse gas emissions. This integrated solution carries many other associated benefits, amongst which are the possibility of introducing vehicle-to-grid (V2G) distributed power generation; introducing IT intelligence to the grid, and creating virtual power plants from distributed sources; and providing new applications for carbon credits in the decarbonisation of the economy. The countries and regions that have signed on to this model and are working to introduce it in 2009–2011 include Israel, Denmark, Australia, and in the US, the Bay Area cities and the state of Hawaii.     

Techno-economical evaluation of a hydrogen refuelling station powered by Wind-PV hybrid power system: A case study for İzmir-Çeşme

Hydrogen fuelling station is an infrastructure for the commercialisation of hydrogen energy utilising fuel cells, particularly, in the automotive sector. Hydrogen fuel produced by renewable sources such as the solar and wind energy can be an alternative fuel to depress the use of fuels based on fossil sources in the transport sector for sustainable clean energy strategy in future. By replacing the primary fuel with hydrogen fuel produced using renewable sources in road transport sector, environmental benefits can be achieved. In the present study, techno-economic analysis of hydrogen refuelling station powered by wind-photovoltaics (PV) hybrid power system to be installed in ?zmir-Çe?me, Turkey is performed. This analysis is carried out to a design of hydrogen refuelling station which is refuelling 25 fuel cell electric vehicles on a daily basis using hybrid optimisation model for electric renewable (HOMER) software. In this study, National Aeronautics and Space Administration (NASA) surface meteorology and solar energy database were used. Therefore, the average wind speed during the year was assessed to be 5.72 m/s and the annual average solar irradiation was used to be 5.08 kW h/m²/day for the considered site. According to optimisation results obtained for the proposed configuration, the levelised cost of hydrogen production was found to be US $7.526–7.866/kg in different system configurations. These results show that hydrogen refuelling station powered by renewable energy is economically appropriate for the considered site. It is expected that this study is the pre-feasibility study and obtained results encougare the hydrogen refuelling station to be established in Turkey by inventors or public institutions.     

A realistic framework to a greener supply chain for electric vehicles

The quantity of electric vehicles in the transport sector has steadily risen over the last 10 years. Most developed countries and China have laid out ambitious plans for electric vehicles penetration. However, there are several challenges that must be addressed on the supply‐chain side of the problem for a successful transition toward an alternative and less environmentally harmful transport system. This study proposes a methodology for the optimal plan and decision making of primary energy sources, electricity generation, electricity distribution to vehicles' charging stations, carbon capture and sequestration, and electric vehicles' charging stations network to satisfy the electricity demand of the overall economy including electric vehicles at a regional/countrywide level under operation and green constraints. The optimization problem was modeled as a mixed integer program in general algebraic modeling system (GAMS). The formulation was employed to propose the upcoming electricity supply chain for electric vehicles in the most populous German state (North Rhine‐Westphalia) in 2025. The optimization show that fossil‐based power still controls the generation in 2025, while carbon capture and sequestration along with higher renewable penetration help meeting the state's greenhouse gases (GHG) emission target. The charging stations network expansion consists of 12 820 charging points mainly alternating current (AC) chargers (22‐kW capacity).     

Fuel cell electric vehicle as a power plant: Fully renewable integrated transport and energy system design and analysis for smart city areas

Reliable and affordable future zero emission power, heat and transport systems require efficient and versatile energy storage and distribution systems. This paper answers the question whether for city areas, solar and wind electricity together with fuel cell electric vehicles as energy generators and distributors and hydrogen as energy carrier, can provide a 100% renewable, reliable and cost effective energy system, for power, heat, and transport. A smart city area is designed and dimensioned based on European statistics. Technological and cost data is collected of all system components, using existing technologies and well-documented projections, for a Near Future and Mid Century scenario. An energy balance and cost analysis is performed. The smart city area can be balanced requiring 20% of the car fleet to be fuel cell vehicles in a Mid Century scenario. The system levelized cost in the Mid Century scenario is 0.09 €/kWh for electricity, 2.4 €/kg for hydrogen and specific energy cost for passenger cars is 0.02 €/km. These results compare favorably with other studies describing fully renewable power, heat and transport systems.     

The hydrogen economy: technology,logistics and economics

Abstract

There is much current discussion on the contribution the 'hydrogen economy' can make to a 'sustainable energy system', centring around the environmental and supply advantages that may accrue from use of hydrogen as a secondary energy carrier. Whether generated by electrolysis or reforming, or even produced locally at filling stations, the hydrogen must be packaged by compression or liquefaction, transported by surface vehicles or pipelines, stored and transferred to the end user. Hydrogen may represent an option for clean energy use if produced using reduced carbon or carbon-free primary energy sources, e.g. renewable, biomass or nuclear energy. To date, hydrogen has competed with direct use of clean primary energy and/or electrical energy produced without CO₂ emissions. However, to succeed as a secondary energy carrier, hydrogen must demonstrate advantages over established systems, especially electricity.     

Managing peak loads in energy grids: Comparative economic analysis

One of the key issues in modern energy technology is managing the imbalance between the generated power and the load, particularly during times of peak demand. The increasing use of renewable energy sources makes this problem even more acute. Various existing technologies, including stationary battery energy storage systems (BESS), can be employed to provide additional power during peak demand times. In the future, integration of on-board batteries of the growing fleet of electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) into the grid can provide power during peak demand hours (vehicle-to-grid, or V2G technology).This work provides cost estimates of managing peak energy demands using traditional technologies, such as maneuverable power plants, conventional hydroelectric, pumped storage plants and peaker generators, as well as BESS and V2G technologies. The derived estimates provide both per kWh and kW year of energy supplied to the grid. The analysis demonstrates that the use of battery storage is economically justified for short peak demand periods of <1 h. For longer durations, the most suitable technology remains the use of maneuverable steam gas power plants, gas turbine,reciprocating gas engine peaker generators, conventional hydroelectric, pumped storage plants.     

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.     

Life cycle analysis of hydrogen fuel: a methodology for a strategic approach of decision making

Two examples are considered in this work in order to show possible settings for decision making in the strategic field of energy: transport vehicles and wastewater treatment plant that are powered by a fuel cell. The environmental impact, measured by evaluating hydrogen life cycle as fuel, varies depending on the source of hydrogen, the process, and the complexity of the productive chain. Nowadays, starting from this point of view, it is possible to get a lot more benefits when hydrogen is directly produced in situ from renewable sources of energy and it is used to make a fuel cell work, as an alternative to an external electric energy source. Future work must be focalized to decrease technological development gap between fuel cells and clean hydrogen extraction, before use of fuel cell would be massive.     

Stochastic optimal charging of electric-drive vehicles with renewable energy

The paper presents the stochastic optimization algorithm that may eventually be used by electric energy suppliers to coordinate charging of electric-drive vehicles (EDVs) in order to maximize the use of renewable energy in transportation. Due to the stochastic nature of transportation patterns, the Monte Carlo simulation is applied to model uncertainties presented by numerous scenarios. To reduce the problem complexity, the simulated driving patterns are not individually considered in the optimization but clustered into fleets using the GAMS/SCENRED tool. Uncertainties of production of renewable energy sources (RESs) are presented by statistical central moments that are further considered in Hong’s 2-point + 1 estimation method in order to define estimate points considered in the optimization. Case studies illustrate the application of the proposed optimization in achieving maximal exploitation of RESs in transportation by EDVs.     

Hydrogen as an energy vector in the islands’ energy supply

Hydrogen as an energy vector can increase penetration of renewable and intermittent sources in the energy supply of the islands and it can serve as an energy vector that may allow reaching 100% renewable energy supply of island communities. This article presents summary of the results of several case studies: Island of Mljet—Croatia, Porto Santo—Madeira, Terceira—Azores, and Malta. The islands were analysed by RenewIslands methodology and it was decided to apply hydrogen as an energy vector. Different scenarios for each island were modelled by H₂RES software and required installed powers of necessary technological options are described for chosen scenarios.     

Comparative analyses of seven technologies to facilitate the integration of fluctuating renewable energy sources

An analysis of seven different technologies is presented. The technologies integrate fluctuating renewable energy sources (RES) such as wind power production into the electricity supply, and the Danish energy system is used as a case. Comprehensive hour-by-hour energy system analyses are conducted of a complete system meeting electricity, heat and transport demands, and including RES, power plants, and combined heat and power production (CHP) for district heating and transport technologies. In conclusion, the most fuel-efficient and least-cost technologies are identified through energy system and feasibility analyses. Large-scale heat pumps prove to be especially promising as they efficiently reduce the production of excess electricity. Flexible electricity demand and electric boilers are low-cost solutions, but their improvement of fuel efficiency is rather limited. Battery electric vehicles constitute the most promising transport integration technology compared with hydrogen fuel cell vehicles (HFCVs). The costs of integrating RES with electrolysers for HFCVs, CHP and micro fuel cell CHP are reduced significantly with more than 50% of RES.     

The research agenda on social acceptance of distributed generation in smart grids: Renewable as common pool resources

The rapid developing literature on ‘smart grids’ suggests that these will facilitate ‘distributed generation’ (DG) preferably from renewable sources. However, the current development of smart (micro)grids with substantial amount of DG (“DisGenMiGrids”) suffers from a focus on mere ‘technology’. Ongoing problems with deployment of renewable energy have shown that implementation is largely determined by broad social acceptance issues. This smart grid development is very important for further renewables deployment, but again there is a tendency to continue the neglect of social determinants.Most technical studies apply implicit and largely unfounded assumptions about the participation in and contribution of actors to DisGenMiGrid systems. This lack of understanding will have severe consequences: smart grids will not further renewables deployment when there are hardly actors that are willing to become part of them. This review is a first attempt to address the social construction of smart electricity grids. As institutional factors have proved to be the main determinants of acceptance, these will also be crucial for further renewables deployment in micro-grid communities. Elaboration of the institutional character of social acceptance and renewables’ innovation calls for an institutional theory approach involving Common Pool Resources management, because these socio-technical systems aim to optimise the exploitation of natural resources. Citizens/consumers and other end-users increasingly have the option to become more self-sufficient by becoming co-producers of electricity.They may optimise the contribution of DG when they cooperate and insert their renewable energy in a cooperative microgrid with mutual delivery. Moreover, the option to include ‘distributed storage’ capacity (electric vehicles) in these microgrids, enables an increasing share of renewables deployment. However, all these options should be institutionally opened. This requires much self-governance and flexible overall regulation that allows microgrids.The research agenda should focus on how such new systems become institutionally embedded, and how they are socially constructed.     

A comparative study of critical factors influencing the renewable energy systems use in the Indian context

The use of renewable energy technologies in developing countries has steadily increased over the past few decades. The widespread use of renewable sources requires a greater understanding of the available options. In order to ascertain the quantum of acceptance of renewable energy sources in the context of possible deterioration of the environment, on account of the increased use of fossil fuels, a Delphi study had been conducted. The feedback from the study was collected and analysed, so as to arrive at a general consensus. By the year 2020, the renewable energy contribution is expected to be 25% of the total energy use in India. At that time, the main resources utilised would be biomass, wind and solar in the order of their quantum of use. Using skewness and rank correlation analysis the results of the Delphi study were studied. It is identified that price, equipment efficiency and technology are the critical factors for commercialising renewable energy sources as denoted by skewness coefficients of 11.6, 5.55 and 0.68, respectively. Rank correlation indicates that the correlation between biomass gasifier electric conversion and biogas electric conversion for lighting is positive, denoting the possibility of integration of the two systems. Similarly, it has been analysed for integrated systems in the area of cooking, pumping, heating, cooling and transportation. This study will help in the formation of strategies which will ensure the development of the optimal integrated energy systems for continuous power supply.     

H2RES,Energy planning tool for island energy systems – The case of the Island of Mljet

When it comes to the energy planning, computer programs like H₂RES are becoming valuable tools. H₂RES has been designed as support for simulation of different scenarios devised by RenewIsland methodology with specific purpose to increase integration of renewable sources and hydrogen into island energy systems. The model can use wind, solar, hydro, biomass, geothermal as renewable energy sources and fossil fuel blocks and grid connection with mainland as back up. The load in the model can be represented by hourly and deferrable electricity loads of the power system, by hourly heat load, by hydrogen load for transport and by water load depending on water consumption. The H₂RES model also has ability to integrate different storages into island energy system in order to increase the penetration of intermittent renewable energy sources or to achieve a 100% renewable island. Energy storages could vary from hydrogen loop (fuel cell, electrolyser and hydrogen storage) to reversible hydro or batteries for smaller energy systems. The H₂RES model was tested on the power system of the Island of Porto Santo – Madeira, the islands of Corvo, Graciosa, and Terrciera – Azores, Sal Island – Cape Verde, Portugal, the Island of Mljet, Croatia and on the energy system of the Malta. Beside energy planning of the islands, H₂RES model could be successfully applied for simulation of other energy systems like villages in mountain regions or for simulation of different individual energy producers or consumers.     

Beyond batteries: An examination of the benefits and barriers to plug-in hybrid electric vehicles (PHEVs) and a vehicle-to-grid (V2G) transition

This paper explores both the promise and the possible pitfalls of the plug-in hybrid electric vehicles (PHEV) and vehicle-to-grid (V2G) concept, focusing first on its definition and then on its technical state-of-the-art. More originally, the paper assesses significant, though often overlooked, social barriers to the wider use of PHEVs (a likely precursor to V2G) and implementation of a V2G transition. The article disputes the idea that the only important barriers facing the greater use of PHEVs and V2G systems are technical. Instead, it provides a broader assessment situating such “technical” barriers alongside more subtle impediments relating to social and cultural values, business practices, and political interests. The history of other energy transitions, and more specifically the history of renewable energy technologies, implies that these “socio-technical” obstacles may be just as important to any V2G transition—and perhaps even more difficult to overcome. Analogously, the article illuminates the policy implications of such barriers, emphasizing what policymakers need to achieve a transition to a V2G and PHEV world.