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Abstract Renewable energy can reduce greenhouse gas emissions by providing renewable electricity, heating, cooling and transportation. The main disadvantage of renewable energy supply is that once it reached a high share in electricity generation, the intermittency caused by renewable energy sources makes balancing of the energy system challenging. This study answers the question "What is the impact of renewable energy on public investment in R&D of energy storage technologies?" Empirical literature studying investments in renewable energy technologies is abundant, however empirical literature studying investments in energy storage technologies is highly limited. Using annual panel data from 28 OECD countries over the period 1990-2014 this paper provides an empirical evidence on the role of renewable energy deployment on public investments in energy storage technologies. The results of fixed effects estimation provide an empirical evidence that governments from countries with greater share of renewable energy invest more in energy storage technologies. Drawing from the empirical results, this paper provides policy recommendations on the need in investments in energy storage technologies due to a growing supply of renewable energy. Although this paper provides lessons from countries which experienced problems with high share of renewable energy and started to promote energy storage alongside with renewable energy, the results will be useful for policy-makers from developing countries with a growing share of renewable energy in total electricity. [ABSTRACT FROM AUTHOR]

Abstract Communities situated in distant areas are deemed as 'remote' and have either very limited or no access to power grid lines. Therefore, most of these communities greatly depend on diesel-burning for power and heat provision at all times. Nonetheless, nearly 30% of the energy associated with the diesel burning and power generation process is dissipated as heat through the exhaust streams of diesel generators. The waste heat in the exhaust stream is usually recovered during the winter season and directly used as a heat source when the communal heat demand is peaked. However, recovery of this energy potential is usually discarded during the summer period due to the low demand. Seasonal thermal storage on rock piles is a developing concept that can be a low-cost solution to resolve this issue. This paper proposes utilization of the heat wasted through the exhaust stream of diesel generators on rock piles as temporary storage during low demand times. In this sense, a remote cold climate community, such as those of Canada and Norway, is selected and potentiality of the seasonal rock pile thermal storage is investigated and presented. [ABSTRACT FROM AUTHOR]

Abstract Global inclination towards renewable energy projects, facilitates deployment of alternative energy systems in various scales. However, due to the noise in usable energy generation and fluctuations in the source availability, battery units are deemed as an integral part of any mini-grid energy generation system. Although, sharp turns in battery prices have taken place over the last few years, batteries are still one of the largest capital components of such systems. On the other hand, like many other heavy industries, mining industry is also closely interested in renewable energy generation on site because of certain environmental and financial reasons. Nonetheless, the size of feasible energy generation and attached storage units are still forcing mining companies to reconsider. In this regard, renewable energy based coolth storage systems can help mining companies to enhance the financial outcomes of mine air-conditioning projects where heavy refrigeration is demanded. This paper promotes power generation via renewable energy systems and proposes coolth/energy storage by analyzing two options. The financial impact of substituting battery storage units and downsizing the refrigeration plant size by storing the peak demand as coolth was also studied. [ABSTRACT FROM AUTHOR]

Abstract The rapid increase in application of intermittent renewable energy generation has stimulated the development of energy storage system to guarantee a stable supply in electricity grid. As a large-scale storage technology, Liquid Air Energy Storage (LAES) technology has attracted many attractions in recent years due to it offers many unique advantages including high energy density, mature technologies based and geographical-constraint free. However, current LAES has relatively low round trip efficiency (less than 60%) and still needs improvement. In the LAES, the recovered cold energy from the liquid air is insufficient to cool the compressed air to the lowest temperature with the shortage of ~18% and liquid air yield does not achieve the maximum in the charging process; external free cold sources would be needed to further increase the liquid air yield, and the round trip efficiency could easily break through 60%. This paper proposes an innovative LAES system integrated with LNG regasification process, the objectives in this established work are to improve the product yield of liquid air and enhance the overall roundtrip efficiency. Sensibility analysis and exergy efficiency analysis of charging process and discharging process at LAES are discussed. Meanwhile, the comparisons of system performance are made between traditional LAES system and LAES with LNG regasification system (LAES-LNG) at same operating parameters. Through the LAES-LNG system, more liquid air is generated. Results show that relatively higher round trip efficiency could be obtained, with 15-35% enhancement compared with the current LAES. Also, liquid air yield obtains a significant improvement to 0.87. [ABSTRACT FROM AUTHOR]

Abstract The paper introduced a smart renewable energy based microgrid system which is composed of three subsystems: solar photovoltaic subsystem, air source heat pump subsystem and energy storage subsystem. This microgrid system was applied to the demonstration project located in Xining City, Qinghai Province, China. The energy performance of the smart renewable energy based microgrid system was evaluated and compared with that of traditional energy supply system which totally depends on the electricity grid and natural gas. The comparison study demonstrates that the proposed hybrid energy supply system is superior to traditional system, significantly decreasing additional energy consumption for buildings and reducing pollutant emissions. [ABSTRACT FROM AUTHOR]

This study evaluates the use of energy storage technologies coupled to renewable energy sources in rural electrification as a way to address the energy access challenge. Characteristic energy demanding applications will differently affect the operating conditions for off-grid renewable energy systems. This paper discusses and evaluates simulated photovoltaic power output and battery state of charge profiles, using estimated climate data and electricity load profiles for the Altiplanic highland location of Patacamaya in Bolivia to determine the loss of load probability as optimization parameter. Simulations are performed for three rural applications: household, school, and health center. Increase in battery size prevents risk of electricity blackouts while increasing the energy reliability of the system. Moreover, increase of PV module size leads to energy excess conditions for the system reducing its efficiency. The results obtained here are important for the application of off-grid PV-battery systems design in rural electrification projects, as an efficient and reliable source of electricity. [ABSTRACT FROM AUTHOR]

Energy has been the engine of nations’ development, and this has driven mankind towards growing energy needs, in particular for transportation, agricultural and industrial activities and buildings. Energy for transportation is based on oil derived fuel, whereas energy in buildings consists mainly of electricity, which is produced from fossil fuels, nuclear power and/or from renewable energy sources, such as hydro and solar. Agricultural and industrial activities use a combination of fossil fuels and electric energy. To increase the sustainability of energy production and efficient energy use, it is urgent that better monitoring and control systems are used, and increase the energy production from renewable sources. This drives the energy sector towards the need for Life Cycle Analysis of energy processes to support the selection and implementation of more sustainable energy systems, as well as to develop better and more intelligent electric energy grids, where storage energy systems plays an essential role. These questions will be briefly discussed in this paper, focusing in the current situation, existing problems and potential solutions, and expected developments. [ABSTRACT FROM AUTHOR]

The present paper gives an outlook on a bandwidth of required installed power-to-gas capacity in the German power sector fed by 100% renewable generation until 2050. Two scenarios were simulated to quantify cost effects of power-to-gas on the electricity system: once with, once without additional short-term flexibility options to a system using fossil natural gas as sole flexibility option instead. As a result, at latest in 2035, power-to-gas capacity expansion has to take place to reach required installed capacities of up to 89-134 GW in 2050. Application of power-to-gas as long-term flexibility leads to cost savings of up to 11,7-19 bn Euro enabling a fully renewable system in 2050. [ABSTRACT FROM AUTHOR]

According to the Energy Strategy 2050 set forth by the Swiss federal government, Photovoltaic (PV) energy shall make up one fifth of the nation's total energy production in 2050. Such a drastic expansion rate of PV and the resulting excess energy thereof can lead to so-called reverse power flow in the low voltage (LV) grid as demonstrated in previous studies. Power-to-Gas (PtG) represents a suitable storage solution to resolve the situation by absorbing the excess PV energy. This paper presents a qualitative and quantitative feasibility analysis of the PtG technology in the future Swiss LV grid. For this purpose, PtG is integrated in simulation into the grid for absorbing the excess PV energy while producing hydrogen. This hydrogen is assumed to be sold in the mobility sector. Three different operational scenarios are established with respect to the input energy source to the PtG plant, including the excess PV energy, curtailed PV excess energy and PV excess energy plus the energy from the grid. Summing up the results, it can be concluded that the PtG plant is still far from economically viable even though significant improvement can be accomplished to the hydrogen production costs by adopting the active PV curtailment and by purchasing additional energy from the grid. The future study to be undertaken by the authors, with respect to economical viability of the PtG, will include other sources of value, including production of methane as main product, production of oxygen and heat as by-products, and provision of services such as biogas upgrading, frequency regulation and voltage. [ABSTRACT FROM AUTHOR]

This paper presents technology applications and policy options related to energy storage in energy systems or grids. Energy storage technologies are promising tools to achieve a low-carbon future since they allow for the decoupling of energy supply and demand. Energy storage technologies could potentially be deployed across the supply, transmission, distribution and demand portions of an energy system or grid. The services they provide are either based on a power application or an energy application; and they range from long-term seasonal storage to short duration spinning and non-spinning reserves. In terms of energy storage technologies, pumped storage hydropower systems are a mature technology and comprise over 99% of the current total global installed capacity of energy storage technologies, which is evaluated at over 141 GW. In order to achieve widespread deployment, policy options should seek to enable compensation for the multiple services performed across the energy system. [ABSTRACT FROM AUTHOR]

The increasing level in renewable energy capacity presents new challenges. In essence, renewables are weather-dependent and inputs such as solar radiation or wind are not constantly available. The integration of energy storage technologies are important to improve the potential for flexible energy demand and ensure that excess renewable energy can be stored for use at a later time. This paper will explore various types of physical energy storage technologies that are currently employed worldwide. Such examples include direct electrical storage in batteries, thermal storages in hot water tanks or building fabrics via electricity conversion as well as compressed air energy storage. Through this study it has been shown that no single storage system can meet all the criteria to become the ideal energy storage system, each system has its own suitable application range. [ABSTRACT FROM AUTHOR]

Abstract: This paper provides a new framework for the calculation of levelized cost of stored energy. The framework is based on the relations for photovoltaics amended by new parameters. Main outcomes are the high importance of the C rate and the less dominant role of the roundtrip efficiency. The framework allows for comparisons between different storage technologies. The newly developed framework model is applied to derive the LCOE for a PV and storage combined power plant. The derived model enables quick comparison of combined PV and storage power plants with other forms of energy generation, for example diesel generation. This could prove helpful in the current discussion about diesel substitution in off-grid applications. In general, the combined levelized cost of energy lies between the LCOE of PV and LCOE of storage. [Copyright &y& Elsevier]

Abstract: A high penetration of the Renewable Energy Sources (RES) can create stability, reliability and power quality problems in the main electrical grid due to their stochastic nature. The microgrid is one of the analysed solutions to solve this problem. In this context, the storage becomes necessary to better harness the energy generated by RES and to maintain the proper operation of the microgrid. This paper addresses the control of the bidirectional DC-DC converters used to interface a parallel connected Hybrid Energy Storage System (HESS) formed by a Vanadium Redox Battery (VRB) and a SuperCapacitor (SC) bank. The linear controllers have been widely used due to their simple design and implementation. However, their operation is limited to a certain operation range. The variability of the analysed system makes the use of a more robust controller necessary. In this work a PI based two-loop control system and a PI type sliding mode controller (SMC) are compared by means of simulations using the Matlab-Simulink software. Some rules are fixed to facilitate the design process of the SMC and the advantages of using a nonlinear controller are stressed. [Copyright &y& Elsevier]