An Evaluation of Seawater Pumped Hydro Storage for Regulating the Export of Wind Energy to the National Grid

Hydroelectric power generation has been in use for a very long time. From the earliest watermills to the current large scale Hydro power plants, this is a technology that is proven to be reliable and commercially viable. The use of wind energy to provide mechanical power for the purpose of turning a rotor is also not a new concept.Four years ago TCD Professor of Applied Physics Igor Shvets conceived the idea of solving Ireland’s energy crisis by taking these two proven renewable technologies and combining them. (McGreevey, 2012) The spirit of Ireland initiative seeks to resolve the biggest issues facing those involved in wind generated electricity, namely what to do when the wind is not blowing. There has not been a new Pumped Hydro Electric storage Power Plant built in Ireland since Turlough Hill in 1973 and one of the reasons for this may be the high capital costs associated with this type of project. The premise of using the sea as the lower reservoir in a low head, high volume system is at the center of The Spirit of Ireland Proposal. This type of system should offer a lower capital cost, but is it low enough and could it provide a viable source of energy for today’s modern grid

Review of energy system flexibility measures to enable high levels of variable renewable electricity

The paper reviews different approaches, technologies, and strategies to manage large-scale schemes of variable renewable electricity such as solar and wind power. We consider both supply and demand side measures. In addition to presenting energy system flexibility measures, their importance to renewable electricity is discussed. The flexibility measures available range from traditional ones such as grid extension or pumped hydro storage to more advanced strategies such as demand side management and demand side linked approaches, e.g. the use of electric vehicles for storing excess electricity, but also providing grid support services. Advanced batteries may offer new solutions in the future, though the high costs associated with batteries may restrict their use to smaller scale applications. Different “P2Y”-type of strategies, where P stands for surplus renewable power and Y for the energy form or energy service to which this excess in converted to, e.g. thermal energy, hydrogen, gas or mobility are receiving much attention as potential flexibility solutions, making use of the energy system as a whole. To “functionalize” or to assess the value of the various energy system flexibility measures, these need often be put into an electricity/energy market or utility service context. Summarizing, the outlook for managing large amounts of RE power in terms of options available seems to be promising.Peer reviewe

Energy storage systems and grid code requirements for large-scale renewables integration in insular grids

This thesis addresses the topic of energy storage systems supporting increased penetration of renewables in insular systems. An overview of energy storage management, forecasting tools and demand side solutions is carried out, comparing the strategic utilization of storage and other competing strategies. Particular emphasis is given to energy storage systems on islands, as a new contribution to earlier studies, addressing their particular requirements, the most appropriate technologies and existing operating projects throughout the world. Several real-world case studies are presented and discussed in detail. Lead-acid battery design parameters are assessed for energy storage applications on insular grids, comparing different battery models. The wind curtailment mitigation effect by means of energy storage resources is also explored. Grid code requirements for large-scale integration of renewables are discussed in an island context, as another new contribution to earlier studies. The current trends on grid code formulation, towards an improved integration of distributed renewable resources in island systems, are addressed. Finally, modeling and control strategies with energy storage systems are addressed. An innovative energy management technique to be used in the day-ahead scheduling of insular systems with Vanadium Redox Flow battery is presented.Esta tese aborda a temática dos sistemas de armazenamento de energia visando o aumento da penetração de energias renováveis em sistemas insulares. Uma visão geral é apresentada acerca da gestão do armazenamento de energia, ferramentas de previsão e soluções do lado da procura de energia, comparando a utilização estratégica do armazenamento e outras estratégias concorrentes. É dada ênfase aos sistemas de armazenamento de energia em ilhas, como uma nova contribuição no estado da arte, abordando as suas necessidades específicas, as tecnologias mais adequadas e os projetos existentes e em funcionamento a nível mundial. Vários casos de estudos reais são apresentados e discutidos em detalhe. Parâmetros de projeto de baterias de chumbo-ácido são avaliados para aplicações de armazenamento de energia em redes insulares, comparando diferentes modelos de baterias. O efeito de redução do potencial de desperdício de energia do vento, recorrendo ao armazenamento de energia, também é perscrutado. As especificidades subjacentes aos códigos de rede para a integração em larga escala de energias renováveis são discutidas em contexto insular, sendo outra nova contribuição no estado da arte. As tendências atuais na elaboração de códigos de rede, no sentido de uma melhor integração da geração distribuída renovável em sistemas insulares, são abordadas. Finalmente, é estudada a modelação e as estratégias de controlo com sistemas de armazenamento de energia. Uma metodologia de gestão de energia inovadora é apresentada para a exploração de curto prazo de sistemas insulares com baterias de fluxo Vanádio Redox

The Future of Power Storage in South Eastern Europe

The European Commission’s Joint Research Centre (JRC) and the Ministry of Energy and Industry of Albania held a joint workshop on the future role of energy storage in South Eastern Europe on 21 -22 October in Tirana. The workshop was attended by 40 specialists from academia, government, regulatory bodies, power industry and consultancies from both EU accession and candidate countries as well as from EU Member States. The participants actively discussed the technical, financial and regulatory challenges of the energy systems of the Western Balkans, and options of how these could be overcome. The event served as a forum for sharing and critically reflecting experience gained in Western Europe during the last decade. The workshop held in Tirana was part of the Enlargement and Integration Action. The present report summarizes the interventions of the participants, the discussions and conclusions of the workshop.JRC.F.6-Energy Technology Policy Outloo

Electricity Market Participation and Investment Planning Frameworks for Energy Storage Systems

The recent trend of increasing share of renewable energy sources (RES) in the generation mix has necessitated new operational and planning studies because of the high degree of uncertainty and variability of these sources. RES such as solar photovoltaic and wind generation are not dispatchable, and when there is excess energy supply during off-peak hours, RES curtailment is required to maintain the demand-supply balance. Furthermore, RES are intermittent resources which have introduced new challenges to the provision of ancillary services that are critical to maintaining the operational reliability of power systems. Energy storage systems (ESS) play a pivotal role in facilitating the integration of RES to mitigate the aforementioned issues. Therefore, there is a growing interest in recent years to examine the potential of ESS in the future electricity grids. This research focuses on developing market participation and investment planning frameworks for ESS considering different ownership structures. First, a novel stochastic planning framework is proposed to determine the optimal battery energy storage system (BESS) capacity and year of installation in an isolated microgrid using a novel representation of the BESS energy diagram. A decomposition-based approach is proposed to solve the problem of stochastic planning of BESS under uncertainty. The optimal decisions minimize the net present value of total expected costs over a multi-year horizon considering optimal BESS operation using a novel matrix representing BESS energy capacity degradation. The proposed approach is solved in two stages as mixed integer linear programming (MILP) problems; the optimal ratings of the BESS are determined in the first stage, while the optimal installation year is determined in the second stage. Extensive studies considering four types of BESS technologies for deterministic, Monte Carlo Simulations, and stochastic cases are presented to demonstrate the effectiveness of the proposed approach. The thesis further studies the investment decisions on BESS installations by a third-party investor in a microgrid. The optimal BESS power rating, energy capacity, and the year of installation are determined while maximizing the investor's profit and simultaneously minimizing the microgrid operational cost. The multi-objective problem is solved using a goal programming approach with a weight assigned to each objective. The BESS is modeled to participate in energy arbitrage and provision of operating reserves to the microgrid, considering its performance parameters and capacity degradation over the planning horizon. Finally, in the third problem addressed in the thesis in the context of electricity markets, the non-strategic and strategic participation of a pumped hydro energy storage (PHES) facility in day-ahead energy and performance-based regulation (PBR) markets, which includes regulation capacity and mileage, are examined. The PHES is modeled with the capability of operating in hydraulic short-circuit (HSC) mode with detailed representation of its operational constraints, and integrated with an energy-cum-PBR market clearing model. For its strategic participation, a bi-level market framework is proposed to determine the optimal offers and bids of the PHES that maximize its profit. The operation of PHES is modeled at the upper level, while the market clearing is modeled in the lower level problem. The bi-level problem is formulated as a mathematical programming with equilibrium constraints (MPEC) model, which is linearized and solved as an MILP problem. Several case studies are carried out to demonstrate the impact of PHES' non-strategic and strategic operations on market outcomes. Furthermore, stochastic case studies are conducted to determine the PHES strategies considering the uncertainty of the net demand and rivals' price and quantity offers

Value of pumped hydro storage in a hybrid energy generation and allocation system

Transition from fossil fuels to renewable sources is inevitable. In this direction, variation and intermittency of renewables can be integrated into the grid by means of hybrid systems that operate as a combination of alternative resources, energy storage and long distance transmission lines. In this study, we propose a two-stage stochastic mixed-integer programming model for sizing an integrated hybrid energy system, in which intermittent solar generation in demand points is supported by pumped hydro storage (PHES) systems and diesel is used as an expensive back-up source. PHES systems work as a combination of pumped storage and conventional hydropower stations since there is also natural streamflow coming to the upper reservoirs that shows significant seasonal and inter-annual variability and uncertainty. With several case studies from India, we examine the role of high hydropower potential in the Himalaya Mountains to support solar energy generation in the form of pumped hydro or conventional hydro system while meeting the demand at various scales. We show that pumped hydro storage can keep the diesel contribution to meet the demand less than 10%, whereas this number can go up to more than 50% for conventional systems where the streamflow potential is limited compared to the demand. We also examine the role of pumped hydro systems in both isolated and connected systems (through inter-regional transmission lines) and show that the benefit of pumped hydro is more significant in isolated systems and resource-sharing in connected systems can substitute for energy storage. In addition, with the help of the proposed model, we show that the upper reservoir size of a pumped hydro system could be lower than the reservoir size of a conventional hydropower system depending on the demand scale and streamflow availability. This means that, most of the current conventional hydropower stations could be converted to pumped hydropower stations without needing to modify the upper reservoir, leading to a significantly reduced diesel contribution and lower system unit cost. © 2017 Elsevier Lt

La electromovilidad como potenciador de la cuota de renovables en sistemas eléctricos en regiones aisladas: El caso de las Islas Canarias

This doctoral thesis is divided into three chapters. These are linked to a single common axis, which is the impact of the electromobility in islanded regions, exploring two different approaches: Supply and demand side. Chapter 1 and 2 address the supply side, focusing on the role of the electric vehicles as energy storage system in isolated regions. These two chapters have been published in two international journals, included in the Journal of Citation Reports. Chapter 1 was published in Sustainability Journal in 2015; and chapter 2, in Modern Power System and Clean Energy Journal in 2016. Chapter 3 addresses the demand side, deepening in aspects that define the potential buyer of the electric vehicle. This chapter has been submitted to Renewable and Sustainable Energy Reviews Journal and its current state is revised and resubmitted. Chapter 1. Impact of Electric Vehicle as Distributed Energy Storage in Isolated Systems: The case of Tenerife. Isolated regions are highly dependent on fossil fuels. The use of endogenous sources and the improvement in energy efficiency in all consumption activities are the two main methods to reduce the dependence on petroleum-derived fuels. Tenerife offers excellent renewable resources (extensive long periods of sun and wind). However, the massive development of these technologies could cause important operational problems within the electric power grids, because of the small size of its system. In this chapter, it is explored the option of coupling an electric vehicle fleet as a distributed energy storage system to boost the share of renewable energies in an isolated power system, i.e., Tenerife island. A model simulator has been used to evaluate five key outputs under alternative scenarios, which are: the renewable share, the energy spilled, the CO2 emissions, the levelised cost of generating electricity, and fuel dependence. A total amount of 30 different scenarios have been evaluated in comparison with the current situation, combining a gradual renewable installed capacity and the introduction of an electric vehicle fleet using alternative charging strategies. Results show that the impact of 50,000 electric vehicles would increase the renewable share in the electricity mix of the island up to 30%, reduce CO2 emissions by 27%, the total cost of electric generation by 6% and the oil internal demand by 16%. Chapter 2. Complementarity of electric vehicles and pumped-hydro as energy storage in small isolated energy systems: case of La Palma, Canary Islands. In this chapter, we analyse a different island in the Canary Islands, which shows different characteristics than Tenerife. The island of La Palma is located on the northwest of the Canary Islands, and its electric system is fairly small. Sustainability policies planned by local authorities are aimed to increase the share of renewable energies and the reduction of fossil energies. However, intermittence and the concentration of unmanageable renewable energies in few locations may hinder the operation of the system. In order to solve these problems, energy storage plays an essential role. The aim of this chapter is to analyse the effects of the introduction of two possible alternatives as a form of energy storage: pumped hydro storage and electric vehicles. For this, we use a simulation model adapted to the features of La Palma, considering different scenarios and the existence of a pumped-hydro energy storage system. Results show that, in the best-case scenario, the installation of an additional 25 MW from renewables (more than double the current power), supported by 20 MW of pumped hydro storage and a fleet of 3361 electric vehicles, would allow the current share of renewables to increase from 11% (in 2015) to 49%. Furthermore, this would lead to a 26% reduction in CO2 emissions, a 10% in costs of generated kWh and a 19% in energy dependence. Chapter 3. Willingness to pay for electric vehicles in island regions: the case of Tenerife, Canary Islands. Electric vehicles could be a sustainable solution to reduce final energy consumption and carbon emissions in the road transport sector. Moreover, mobility characteristics of drivers (i.e., the average driving distance) fit better with current electric vehicle technical features on a small island than in mainland. In this chapter, the penetration of electric vehicles in Tenerife (Canary Islands) is analysed, which is still quite low. Based on data collected through a face-to-face contingent valuation method, the willingness to change and the willingness to pay for an electric vehicle on the island are estimated, which are key factor to understand the potentiality of electric vehicle penetration. In order to provide an appropriate profile of a potential electric car buyer, in the second part of the chapter we analyse the impact of a set of explanatory variables on both willingness to change and willingness to pay. It has been found that providing information about basic properties of an electric cars and environmental concerns are key factors for willingness to change, while income level, mobility patterns, environmental concerns and technological attitude of individuals are found to be important factors to determine willingness to pay

Forecasting tools and probabilistic scheduling approach incorporatins renewables uncertainty for the insular power systems industry

Nowadays, the paradigm shift in the electricity sector and the advent of the smart grid, along with the growing impositions of a gradual reduction of greenhouse gas emissions, pose numerous challenges related with the sustainable management of power systems. The insular power systems industry is heavily dependent on imported energy, namely fossil fuels, and also on seasonal tourism behavior, which strongly influences the local economy. In comparison with the mainland power system, the behavior of insular power systems is highly influenced by the stochastic nature of the renewable energy sources available. The insular electricity grid is particularly sensitive to power quality parameters, mainly to frequency and voltage deviations, and a greater integration of endogenous renewables potential in the power system may affect the overall reliability and security of energy supply, so singular care should be placed in all forecasting and system operation procedures. The goals of this thesis are focused on the development of new decision support tools, for the reliable forecasting of market prices and wind power, for the optimal economic dispatch and unit commitment considering renewable generation, and for the smart control of energy storage systems. The new methodologies developed are tested in real case studies, demonstrating their computational proficiency comparatively to the current state-of-the-art

Assessment of energy storage technologies for case studies with increased renewable energy penetration

This study aspires to assess state of the art storage technologies for five different scenarios including an offshore wind farm, an onshore wind farm, an islanded grid, a microgrid in Egypt and a solar power system. The assessment has been based on two main evaluation tools: The Technology Readiness Level and Applicability Indicators. Based on the evaluated results, it was concluded that mechanical storage technologies are suitable for large scale systems due to their relative high capital cost and power range. Cryogenic Thermal, Molten Salt and Pumped Heat storage systems have achieved a high applicability score in all the case studies which makes them as a promising solution for the near future. Moreover, the development of small scale Pumped Hydro Storage (PHES) and Compressed Air Energy Storage (CAES) systems would be very beneficial since these energy storage systems are the most well developed and commercialized ones. It is also expected that during the next decade thermal storage technologies will play a significant role in the storage scheme due their favorable power characteristics. Finally, efforts should be focused on the reduction of the cost of hydrogen storage because hydrogen storage technology is a promising solution and might compete with PHES and CAES in the future