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[en] We investigate the economic viability of coupling a wind farm with compressed air energy storage (CAES) to participate in the day-ahead electricity market at a time when renewable portfolio standards are not binding and wind competes freely in the marketplace. In our model, the CAES is used to reduce the risk of committing uncertain quantities of wind energy and to shift dispatch of wind generation to high price periods. Other sources of revenue (capacity markets, ancillary services, price arbitrage) are not included in the analysis. We present a model to calculate profit maximizing day-ahead dispatch schedules based on wind forecasts. Annual profits are determined with dispatch schedules and actual wind generation values. We find that annual income for the modeled wind–CAES system would not cover annualized capital costs using market prices from the years 2006 to 2009. We also estimate market prices with a carbon price of $20 and $50 per tonne CO2 and find that revenue would still not cover the capital costs. The implied cost per tonne of avoided CO2 to make a wind–CAES profitable from trading on the day-ahead market is roughly $100, with large variability due to electric power prices. - Highlights: ► We modeled a wind farm participating in the day-ahead electricity market. ► We calculated optimal day-ahead market offers based on wind forecasts. ► Revenue is then calculated using measured wind power. ► We find that revenue is insufficient to cover capital costs at current market prices.
[en] In order to resolve the problems arising from the fact that the production and consumption of electricity are at distinctly levels through much of the day, the electric power companies have been led to adopt different solutions, from the financial inducements to customers to limit their use of appliances, to the design of electric power stations with daily or weekly compressed air energy storage. Faced with fluctuating energy demand situation, the electric power companies are developing an electric base load, produced by basic power stations, hydroelectric (river) stations, nuclear and steam stations. They respond to the fluctuation of demand by starting up stations powered by fuel-oil by more or less sophisticated gas turbine, by hydroelectric energy, or as at Huntorf, by pneumatic stored energy. In this communication, we present the results, the capital cost and the operating cost concerning the combination of pneumatic storage with reciprocating engine and gas turbine. (author)
[en] Highlights: • Thermodynamic analysis is presented for an improved A-CAES combined with PBTES system. • A mathematic model is developed, validated and used to simulate system performances. • PBTES heights have significant influence on the PBTES’s thermal behaviors and the system efficiencies. • The maximum cycle efficiency of the improved A-CAES system is 56.74%. - Abstract: Energy storage technology is a cutting-edge research in the field of new and renewable energy application. In this paper we introduce the concept of an energy storage based on adiabatic compressed air energy storage (A-CAES) combined with packed bed thermal energy storage (PBTES) system. First, the system thermodynamic performance of a typical single cycle is discussed and the effect of PBTES heights is analyzed. The results show that an overall efficiency in excess of 49% is achievable and the PBTES heights have significant influence on the thermal behavior of PBTES, as well as the overall efficiencies. Because there is still heat energy remaining in the packed bed until the discharge process is terminated, an improved A-CAES system with a heat recuperator is further proposed. It is found that this improved system shows a promotion of ∼5% compared with the first present A-CAES system. The cycle efficiency of the improved system increases with the increase of continuous cycles, and then reaches a stable value of 56.74% after around 25 cycles. The main conclusions drawn from this work will be helpful for future development of a high-efficiency A-CAES system combined with PBTES.
[en] The major types of energy storage systems (including conventional batteries, compressed air energy storage, pumped hydro and superconducting coils) are discussed in this paper. 8 bibliographies
[en] This document describes the main characteristics of various electric power storage methods and their application domains. The large-scale storages include the hydraulic systems, those using compressed air, the batteries or those implementing a thermal way. The small-scale storages are electrochemical as the accumulators, the super-capacitors, mechanical as the flywheel, magnetic or also by the hydrogen use. The first part presents the necessity of the electric power storage, the second part the places of these storage. The third part details the forms of storage. (A.L.B.)
[en] This article examines how the ability to ''store'' electricity can pay handsome dividends in a competitive environment. Priorities change when industries are deregulated. Indeed, new priorities are being established for electric generation--low cost, efficiency, product distinction for marketing purposes, etc. are all more critical today. Perhaps not so obvious is the fundamental role of energy storage in a fully competitive marketplace. In fact, rarely do a technology development and a changing business climate play off against each other so nicely. Consider the function of the emerging electricity broker, or power marketer. Imagine the premium that broker could command with access to a large increment of electricity--purchased at a low price--and supplied at a moment's notice for a substantially higher price. Storage of electricity would mean that the investment in excess available generation capacity to supply so-called peak demand could be avoided. It also means that electricity could be brokered like other commodities--that is purchased, stockpiled, and sold to reflect market conditions across a wider geographical region and time spain. Benefits accrue to transmission and distribution, in addition to generation. Energy storage helps to manage the increasing stress placed on the grid as a result of intermittent sources of power and large numbers of cogenerators and small power producers. On the customer side, any ratepayer large or small could, theoretically, play the spot market in electric supply with a reserve to tap in emergencies. For a parallel in other deregulated markets, recall how storage has become an important factor in natural-gas contracting. Quality of electricity also can be improved by applying storage to stabilize the grid, especially along the distribution system at substations. And the opening of vast markets for electricity consumption, such as electric vehicles, depends in large measure on electric storage
[en] Wind energy is an important field of development for the island of Gotland, Sweden, especially since the island has set targets to generate 100% of its energy from renewable sources by 2025. Due to the variability of wind conditions, energy storage will be an important technology to facilitate the continued development of wind energy on Gotland and ensure a stable and secure supply of electricity. In this study, the feasibility of utilizing the Middle Cambrian Faludden sandstone reservoir on Gotland for Compressed Air Energy Storage (CAES) is assessed. Firstly, a characterization of the sandstone beneath Gotland is presented, which includes detailed maps of reservoir thickness and top reservoir structure. Analysis of this information shows that the properties of the Faludden sandstone and associated cap rock appear favorable for the application of CAES. Seven structural closures are identified below the eastern and southern parts of Gotland, which could potentially be utilized for CAES. Scoping estimates of the energy storage capacity and flow rate for these closures within the Faludden sandstone show that industrial scale CAES could be possible on Gotland.
[en] Future sustainable energy systems call for the introduction of integrated storage technologies. One of these technologies is compressed air energy storage (CAES). In Denmark at present, wind power meets 20% and combined heat and power production (CHP) meets 50% of the electricity demand. Based on these figures, the paper assesses the value of integrating CAES into future sustainable energy systems with even higher shares of fluctuating renewable energy sources. The evaluation is made on the basis of detailed energy system analyses in which the supply of complete national energy systems is calculated hour by hour in relation to the demands during a year. The Danish case is evaluated in a system-economic perspective by comparing the economic benefits achieved by improving the integration of wind power to the costs of the CAES technology. The result is compared to various other storage options. Furthermore, a business-economic evaluation is done by calculating the potential income of the CAES technology from both spot markets and regulating power markets. The evaluation includes both historical hour by hour prices during a 7-year period on the Nordic Nord Pool market as well as expected future price variations. The conclusion is that even in energy systems with very high shares of wind power and CHP, neither the historical nor the expected future price variations on the spot market alone can justify the investment in CAES systems. Other storage technology options are significantly more feasible. CAES may operate both on the spot market and the regulating power market, which indicates potential feasibility. However, such strategy is highly risky because of the small extent of the regulating power market and if CAES is to become feasible it will depend on incomes from auxiliary services. (author)
[en] Electricity generated from renewable wind sources is highly erratic due to the intermittent nature of wind. This uncertainty of wind power can lead to challenges regarding power system operation and dispatch. Energy storage system in conjunction with wind energy system can offset these effects, making the wind power controllable. Moreover, the power spectrum of wind power exhibits that the fluctuations of wind power include various components with different frequencies and amplitudes. Thus, the hybrid energy storage system is more suitable for smoothing out the wind power fluctuations effectively rather than the independent energy storage system. A hybrid energy storage system consisting of adiabatic compressed air energy storage (A-CAES) system and flywheel energy storage system (FESS) is proposed for wind energy application. The design of the proposed system is laid out firstly. The A-CAES system operates in variable cavern pressure, constant turbine inlet pressure mode, whereas the FESS is controlled by constant power strategy. Then, the off-design analysis of the proposed system is carried out. Meanwhile, a parametric analysis is also performed to investigate the effects of several parameters on the system performance, including the ambient conditions, inlet temperature of compressor, storage cavern temperature, maximum and minimum pressures of storage cavern. - Highlights: • A wind-hybrid energy storage system composed of A-CAES and FESS is proposed. • The design of the proposed hybrid energy storage system is laid out. • The off-design analysis of the proposed system is carried out. • A parametric analysis is conducted to examine the system performance
[en] A computer-simulation model of the behaviour of a photovoltaic (PV) gas-turbine hybrid system, with a compressed-air store, is developed in order to evaluate its performance as well as predict the total energy-conversion efficiency and the incurred costs under various operating conditions. This integrated PV and gas-turbine hybrid plant produces approximately 140% more power per unit of fuel consumed compared with corresponding conventional gas-turbine plants. In addition, lower rates of pollutant emissions to the atmosphere per kWh of electricity generated are achieved. (Author)