The delivery of low-cost,low-carbon rural energy services

The provision of both electrical and mechanical energy services can play a critical role in poverty alleviation for the almost two billion rural users who currently lack access to electricity. Distributed generation using diesel generators remains a common means of electricity provision for rural communities throughout the world. Due to rising fuel costs, the need to address poverty, and consequences of global warming, it is necessary to develop cost efficient means of reducing fossil fuel consumption in isolated diesel microgrids. Based on a case study in Nicaragua, a set of demand and supply side measures are ordered by their annualized costs in order to approximate an energy supply curve. The curve highlights significant opportunities for reducing the costs of delivering energy services while also transitioning to a carbon-free electrical system. In particular, the study demonstrates the significant cost savings resulting from the implementation of conventional metering, efficient residential lighting, and electricity generation using renewable energy sources.     

Spatial development of hydrogen economy in a low-carbon UK energy system

Hydrogen technologies and infrastructures might play a significant role in meeting ambitious climate and energy policy goals of the UK Government. Nonetheless, studies on hydrogen are either limited in scope in that they do not take into account the relationships with the wider energy system drivers and constraints or do not consider how a hydrogen network might develop geographically. This paper presents a framework where a spatially explicit hydrogen module is embedded in the UK MARKAL Energy System model to explore energy system trade-offs for the production, delivery and use of hydrogen at the sub-national level. A set of illustrative scenarios highlight the competitiveness of hydrogen related infrastructures and technologies as well as imported liquid hydrogen against a stringent emissions reduction target; the effect of emissions reduction trajectory on the development of hydrogen network; the intense resource competition between low carbon hydrogen production and electricity generation, and the importance of economies of scale in hydrogen supply and distribution.     

Soft-linking energy systems and GIS models to investigate spatial hydrogen infrastructure development in a low-carbon UK energy system

This paper describes an innovative modelling approach focusing on linking spatial (GIS) modelling of hydrogen (H₂) supply, demands and infrastructures, anchored within a economy-wide energy systems model (MARKAL). The UK government is legislating a groundbreaking climate change mitigation target for a 60% CO₂ reduction by 2050, and has identified H₂ infrastructures and technologies as potentially playing a major role, notably in the transport sector. An exploratory set of linked GIS–MARKAL model scenarios generate a range of nuanced insights including spatial matching of supply and demand for optimal zero-carbon H₂ deployment, a crucial finding on successive clustering of demand centres to enable economies of scale in H₂ supply and distribution, the competitiveness of imported liquid H₂ and of liquid H₂ distribution, and sectoral competition for coal with carbon sequestration between electricity and H₂ production under economy-wide CO₂ constraints.     

A review of computer tools for analysing the integration of renewable energy into various energy systems

This paper includes a review of the different computer tools that can be used to analyse the integration of renewable energy. Initially 68 tools were considered, but 37 were included in the final analysis which was carried out in collaboration with the tool developers or recommended points of contact. The results in this paper provide the information necessary to identify a suitable energy tool for analysing the integration of renewable energy into various energy-systems under different objectives. It is evident from this paper that there is no energy tool that addresses all issues related to integrating renewable energy, but instead the ‘ideal’ energy tool is highly dependent on the specific objectives that must be fulfilled. The typical applications for the 37 tools reviewed (from analysing single-building systems to national energy-systems), combined with numerous other factors such as the energy-sectors considered, technologies accounted for, time parameters used, tool availability, and previous studies, will alter the perception of the ‘ideal’ energy tool. In conclusion, this paper provides the information necessary to direct the decision-maker towards a suitable energy tool for an analysis that must be completed.     

Integrated modelling of material flows and energy systems (MIMES)

A comprehensive nonlinear programming model, MIMES, for the optimization of linked material and energy flow systems is presented. The model is generic, intended for systems that can be described by materials and energy balances but where the details of phase transitions and chemical reactions can be omitted. It fills a niche between energy systems engineering and process flowsheeting models. Issues suitable for analysis by the model range from energy conservation in industrial plants, specific industries or industrial subsectors to municipal waste management and fuels and materials life cycle analysis. MIMES is implemented on PC (386/486). The model is demonstrated for a paper production line in a paper mill. This example shows how the model can be used for joint analysis of energy and water conservation, substitution of energy carriers, and utilization of waste heat outside the system.     

Medium term market perspectives,goal prices and competitiveness of renewable resources in the Italian energy system

Using a multiperiodal LP model (MARKAL) the authors assessed the likely potential of solar thermal and biogas systems under various circumstances. The study covered the period 1980–2005, in five segments of five years. It focused only on the subsystem of the energy end-uses which can be substituted for by solar and biogas technologies. In this paper we show the main results of the study regarding the competitiveness of the single solar and biogas technologies in different scenarios and their sensitivity to incentives and prices, together with the essential technical data regarding demand and supply technologies which produced those results. The analysis performed of the potential penetration of renewable technologies into the Italian energy system shows that their contribution will remain very marginal if the price of conventional energy carriers remains constant in constant money. However, the objective of removing with renewable technologies 1.5 per cent of the total Italian energy consumption appears to be realistic in the short-medium term.     

Hydrogen supply chain architecture for bottom-up energy systems models. Part 1: Developing pathways

The integration of hydrogen energy systems in the overall energy system is an important and complex subject for hydrogen supply chain management. The efficiency of the integration depends on finding optimum pathways for hydrogen supply. Accordingly, energy systems modelling methods and tools have been implemented to obtain the best configuration of hydrogen processes for a defined system. The appropriate representation of hydrogen technologies becomes an important stage for energy system modelling activities. This study, split in consecutive parts, has been conducted to analyse how representative hydrogen supply pathways can be integrated in energy systems modelling. The current paper, the first part of a larger study, presents stylised pathways of hydrogen supply chain options, derived on the basis of a detailed literature review. It aims at establishing a reference hydrogen energy system architecture for energy modelling tools. The subsequent papers of the study will discuss the techno-economic assumptions of the hydrogen supply chain components for energy modelling purposes.     

The energy storage mathematical models for simulation and comprehensive analysis of power system dynamics: A review. Part i

Energy storage systems are increasingly used as part of electric power systems to solve various problems of power supply reliability. With increasing power of the energy storage systems and the share of their use in electric power systems, their influence on operation modes and transient processes becomes significant. In this case, there is a need to take into account their properties in mathematical models of real dimension power systems in the study of various operation modes, design, etc. In this article the main types of energy storage devices, as well as the fields and applications of their use in electric power systems are considered. The principles of realization of detailed mathematical models, principles of their control systems are described for the presented types of energy storage systems. The article is an overview and can help in choosing a mathematical model of energy storage system to solve the necessary tasks in the mathematical modeling of storage systems in electric power systems.Information is presented on large hydrogen energy storage units for use in the power system.     

Numerical study of energy separation in a vortex tube with different RANS models

The aim of the present paper is to investigate numerically the energy separation mechanism and flow phenomena within a vortex tube. A 3D computational domain has been generated considering the quarter of the geometry and assuming periodicity in the Azimuthal direction which was found to exhibit correctly the general behaviour expected from a vortex tube. Air is selected as the working fluid. The flow predictions reported here are based upon four turbulence models, namely, the k–?, k–ω and SST k–ω two-equations models and the second moment closure model (RSM). The models results are compared to experimental data obtained from the literature. Four cases have been considered by changing the inlet pressure from 200 up to 380 kPa. It has been observed that all the above mentioned models are capable of predicting fairly well the general flow features but only the advanced RSM model is capable of matching correctly the measured cold and hot outlet temperatures. All the other models over predict the mean temperature difference by values up to twice the measured data.     

Assessing the impacts of technology improvements on the deployment of marine energy in Europe with an energy system perspective

Marine energy could play a significant role in the long-term energy system in Europe, and substantial resources have been allocated to research and development in this field. The main objective of this paper is to assess how technology improvements affect the deployment of marine energy in the EU. To do so the linear optimization, technology-rich model JRC-EU-TIMES is used. A sensitivity analysis is performed, varying technology costs and conversion efficiency under two different carbon-emissions paths for Europe: a current policy initiative scenario and a scenario with long-term overall CO₂ emission reductions. We conclude that, within the range of technology improvements explored, wave energy does not become cost-competitive in the modelled horizon. For tidal energy, although costs are important in determining its deployment, conversion efficiency also plays a crucial role. Ensuring the cost-effectiveness of tidal power by 2030 requires efficiency improvements by 40% above current expectations or cost reductions by 50%. High carbon prices are also needed to improve the competitiveness of marine energy. Finally, our results indicate that investing 0.1–1.1 BEuro₂₀₁₀ per year in R&D and innovation for the marine power industry could be cost-effective in the EU, if leading to cost reduction or efficiency improvements in the range explored.     

Renewable energy technologies for irrigation water pumping in India: projected levels of dissemination, energy delivery and investment requirements using available diffusion models

Using the past diffusion trends of four renewable energy technologies for irrigation water pumping in India (SPV pumps, windmill pumps and biogas/producer gas driven dual fuel engine pumps), results of an attempt to project their future dissemination levels, have been presented in this study. The likely contribution of the renewable energy options considered in the study to the projected energy demand for irrigation water pumping in India has been estimated. Estimates of the associated investment requirements taking into account the learning effect have also been presented.     

Methodologies for representing the road transport sector in energy system models

Energy system models are often used to assess the potential role of hydrogen and electric powertrains for reducing transport CO₂ emissions in the future. In this paper, we review how different energy system models have represented both vehicles and fuel infrastructure in the past and we provide guidelines for their representation in the future. In particular, we identify three key modelling decisions: the degree of car market segmentation, the imposition of market share constraints and the use of lumpy investments to represent infrastructure. We examine each of these decisions in a case study using the UK MARKAL model. While disaggregating the car market principally affects only the transition rate to the optimum mix of technologies, market share constraints can greatly change the optimum mix so should be chosen carefully. In contrast, modelling infrastructure using lumpy investments has little impact on the model results. We identify the development of new methodologies to represent the impact of behavioural change on transport demand as a key challenge for improving energy system models in the future.     

Robust design of a future 100% renewable european energy supply system with hydrogen infrastructure

Variable renewable energy sources (VRES) will be the cornerstones of future energy supply systems. Nevertheless, their inherent intermittency remains an obstacle to their widespread deployment. Renewably-produced or ‘green’ hydrogen has been suggested as an energy carrier that could account for this in a sustainable manner. In this study, a fully VRES-based European energy system in the year 2050 is designed using an iterative minimal cost-optimization approach that ensures robust supply security across 38 weather-year scenarios (1980–2017). The impact of different power generation locations is factored in by defining exclusive VRES groups within each optimization region. From this, it can be seen that higher numbers of groups in each region offer cheaper electricity generation locations to the optimizer and thus decrease the system's total annual costs. Furthermore, the robust system design and impact of inter-annual variability is identified by iteratively combining the installed capacities of different system designs derived through the application of the 38 historical weather years. The system design outlined here has significantly lower capacities in comparison to the maximum regional capacities obtained in the first round of optimization.     

Assessing low-carbon energy technologies against sustainability and resilience criteria: results of a European experts survey

The aim of this article is the assessment of low-carbon energy technologies in Europe against a set of sustainability and resilience criteria. The assessment was based on a survey that was conducted among 40 European experts. Solar Photovoltaic was the technology that proved to achieve high performance against many criteria, whereas nuclear was assessed by the experts with relatively low performance against most of the criteria. Furthermore, it became evident that there is high degree of convergence between the experts, and therefore high degree of confidence, on specific aspects such as the high level of public resistance against Nuclear and the low stability of energy generation of wind onshore. The experts had major disagreements on the performance of carbon capture and storage (CCS) technologies against technological maturity and innovative ability criteria, which reveals a high degree of uncertainty on how CCS will be deployed in the future, pointing out a direction for future research.     

Liquid Organic Hydrogen Carriers as an efficient vector for the transport and storage of renewable energy

This contribution proposes the usage of Liquid Organic Hydrogen Carriers (LOHC) for the storage and subsequently the transport of renewable energy. It is expected that a significant share of future energy consumption will be satisfied with the import of energy coming from regions with high potential for renewable generation, e.g. the import of solar power from Northern Africa to Europe. In this context the transport of energy in form of chemical carriers is proposed supplementary to electrical transmission. Because of their high storage density and good manageability under ambient conditions Diesel-like LOHC substances could be transported within the infrastructure that already exists for the handling of liquid fossil fuels (e.g. oil tankers, tank trucks, pipelines, etc.). A detailed assessment of energy consumption as well as of transport costs is conducted that confirms the feasibility of the concept.     

Exploring past energy changes and their implications for the pace of penetration of new energy technologies

Possible growth paths for new electricity generation technologies are investigated on the basis of an empirical analysis of past penetration rates. Finding and understanding high market penetration scenarios is relevant to formulating climate change mitigation strategies. The analysis shows that under favorable growth conditions, photovoltaics and wind could produce 15% and 25%, respectively, of world electricity by 2050. Under the same assumptions nuclear power could increase to 41% of world electricity. But it is unlikely that all three technology paths could be realized up to these values simultaneously and therefore the penetration rates presented here should be considered as indicative only. The results show that under positive conditions, an embryonic technology could move as a preferred option into a mainstream energy source within half a century. The introduction of growth constraints reflecting, e.g., severe economic, technical, or political limitations could reduce the above numbers by a factor of up to 2–3. The results indicate a decline in the relative year-to-year growth of new technologies when they have higher market shares. A comparison of the results with other short-term and long-term technology scenarios shows satisfactory agreement.     

Reviewing optimisation criteria for energy systems analyses of renewable energy integration

The utilisation of fluctuating renewable energy sources is increasing world-wide; however, so is the concern about how to integrate these resources into the energy systems. The design of optimal energy resource mixes in climate change mitigation actions is a challenge faced in many places. This optimisation may be implemented according to economic objectives or with a focus on techno-operational aims and within these two main groupings, several different criteria may potentially be applied to the design process.In this article, a series of optimisation criteria are reviewed and subsequently applied to an energy system model of Western Denmark in an analysis of how to use heat pumps for the integration of wind power.The analyses demonstrate that the fact whether the system in question is modelled as operated in island mode or not has a large impact on the definition of the optimal wind power level. If energy savings and CO₂ emission reductions beyond the system boundary are not included in the analysis, then it is either not feasible to expand wind power to a high degree or it is conversely more feasible to install relocation technologies that can utilise any excess production. The analyses also demonstrate that different optimisation criteria render different optimal designs.     

PEM fuel cell degradation effects on the performance of a stand-alone solar energy system

After comparing fresh and degraded performances of Polymer Electrolyte Membrane (PEM) based components of a hydrogen cycle with the help of computational fluid dynamics simulations, recently established stand-alone solar energy system producing hydrogen for energy storage is investigated focusing on the effects of degradation of fuel cells on the overall performance of the system. A complete model of the system has been developed using TRNSYS, and a degraded PEM Fuel Cell Subsystem has been incorporated into the model. Then, the effects of the PEM fuel cell degradation on the overall performance of the energy system are estimated. After reviewing the simulation results, the model shows that the PEM Fuel Cell degradation has a substantial impact on the overall system performance causing a system down time of approximately one month in a typical simulation year. Consequently, the stand-alone system is not capable of operating continuously for a complete year when the PEM fuel cells are degraded. Furthermore, an economic analysis is performed for a project lifetime of 25 years and the Levelized Cost of Electricity (LCE) value of the degraded system is found to be 0.08 $/kWh higher than the newly established system. Nevertheless, LCE calculations that are repeated for declining PV panel costs show that the considered hybrid system may be an economically competitive alternative to conventional diesel generators, even when the degradation of PEM based components and their regular maintenance are considered.     

The status and prospects of renewable energy for combating global warming

Reducing anthropogenic greenhouse gas (GHG) emissions in material quantities, globally, is a critical element in limiting the impacts of global warming. GHG emissions associated with energy extraction and use are a major component of any strategy addressing climate change mitigation. Non-emitting options for electrical power and liquid transportation fuels are increasingly considered key components of an energy system with lower overall environmental impacts. Renewable energy technologies (RETs) as well as biofuels technologies have been accelerating rapidly during the past decades, both in technology performance and cost-competitiveness — and they are increasingly gaining market share. These technology options offer many positive attributes, but also have unique cost/benefit trade-offs, such as land-use competition for bioresources and variability for wind and solar electric generation technologies. This paper presents a brief summary of status, recent progress, some technological highlights for RETs and biofuels, and an analysis of critical issues that must be addressed for RETs to meet a greater share of the global energy requirements and lower GHG emissions.