Merchant electricity transmission expansion: A European case study

We apply a merchant transmission model to the trilateral market coupling (TLC) arrangement among the Netherlands, Belgium and France as an example, and note that it could further be applied to other market splitting or coupling of Europe’s different national power markets. In this merchant framework the system operator allocates financial transmission rights (FTRs) to investors in transmission expansion based upon their preferences, and revenue adequacy. The independent system operator (ISO) preserves some proxy FTRs to manage potential negative externalities that may result from expansion projects. This scheme could help European market coupling arrangements attract additional investment.     

Wave energy resources in sheltered sea areas: A case study of the Baltic Sea

Wave energy is a renewable source, which has not yet been exploited to a large extent. So far the main focus of wave energy conversion has been on the large wave energy resources of the great oceans on northern latitudes. However, large portions of the world potential wave energy resources are found in sheltered waters and calmer seas, which often exhibit a milder, but still steady wave climate. Examples are the Baltic Sea, the Mediterranean and the North Sea in Europe, and ocean areas closer to the equator. Many of the various schemes in the past consist of large mechanical structures, often located near the sea surface. In the present work we instead focus on wave power plants consisting of a number of small wave energy converters, forming large arrays. In this context, we look at advantageous arrangements of point absorbers, and discuss the potential of the Baltic Sea as a case study.     

Conservation and deferral potentials of demand side management programmes: A case study

Demand side management options (DSMO) can reduce the peak electricity demand for utilities. This reduction in demand is helpful to the utility in at least two ways: first, it minimizes the penalty costs of not being able to meet the peak demand and thus it has the potential to reduce costs; second, it also can defer the need for building new power plants and hence it can release, at least for some period of time, the scarce capital (which is especially important for the developing countries) for use in development activities elsewhere. These two benefits have been considered in detail in the paper. An analytical model has been developed to estimate the conservation potential of the DSM programmes. The model is then used to illustrate the benefit derived by deferring the construction of a new power plant. The model has been applied to the Maharashtra State Electricity Board, an electric utility in India, as a case study. Several scenarios have been constructed to account for different levels of the DSM possibilites. A sensitivity analysis has been carried out to tackle some of the uncertainties associated with the assumptions in the analysis.     

Implementation of repowering optimization for an existing photovoltaic‐pumped hydro storage hybrid system: A case study in Sichuan,China

For a remote area or an isolated island, where the grid has not extended, a standalone hybrid energy system can provide cheap and adequate power for local users. However, with the development of society, the load demand will increase and the original system cannot completely meet the load demand. This situation occurs in Xiaojin, Sichuan, China. The existing photovoltaic‐pumped hydro storage (PV‐PHS) hybrid system in this area as the original system cannot completely meet the load requirements at present. The term “repowering” aims to maximize the reliability of power supply and the utilization of the PV‐PHS hybrid energy system that differs from traditional planning optimization to build all components. The repowering strategy is to integrate wind turbines (WTs) and battery into the original system. For the repowering system, a power management strategy is proposed to determine the operating modes of the PHS and battery. Three objectives, which are minimizing percentage of the demand not supplied, levelized cost of energy, and curtailment rate of renewable energy, are considered in the optimization model. Simulation is conducted by single‐objective, biobjective, and triobjective particle swarm optimization (PSO) techniques. For the single‐objective optimization, the comparison of PSO and genetic algorithm (GA) is made. For the double‐objective optimization, multiobjective PSO (MOPSO) is compared with weighted sum approach (WSA), and fuzzy satisfying method is utilized to find the win‐win solution. The results reveal that the repowering strategy can help to achieve maximum reliability of power supply after load demand increases significantly, and the battery plays an important role in such a hybrid system.     

Factors influencing calculation of capacity value of wind power: A case study of the Australian National Electricity Market (NEM)

Calculation of wind power capacity values for risk assessment of power system adequacy has attracted great attention in the literature. And the most popular approach has been the Effective Load Carrying Capability (ELCC) method which allows for the consideration of key factors such as wind capacity factor, forced outage rates (F.O.R) of conventional power stations, system reliability targets, and the correlation between wind availability and system load. However, comparatively little attention has been paid to analysing the effects of other factors such as the number of wind farms and wind installed capacity, the length of historic time series data on demand and wind resources. This paper provides an in-depth analysis of how these factors influence the calculation of capacity value for the Australian National Electricity Market (NEM) power system using metered half-hourly wind and load data for 2006 to 2013. The analysis incorporates the periods with extreme risk events. Our results show that capacity values depend greatly on the design of the simulation model used, and highlight the importance of capturing wind and load data points relating to extremely high demand periods. We compare our NEM-wide estimates to recent estimates for the State of South Australia.     

The impact of increased interconnection on electricity systems with large penetrations of wind generation: A case study of Ireland and Great Britain

Increased interconnection has been highlighted as potentially facilitating the integration of wind generation in power systems by increasing the flexibility to balance the variable wind output. This paper utilizes a stochastic unit commitment model to simulate the impacts of increased interconnection for the island of Ireland with large penetrations of wind generation. The results suggest that increased interconnection should reduce average prices in Ireland, and the variability of those prices. The simulations also suggest that while increased interconnection may reduce carbon dioxide emissions in Ireland, Great Britain would experience an increase in emissions, resulting in total emissions remaining almost unchanged. The studies suggest that increased interconnection would not reduce excess wind generation. This is because under unit commitment techniques which incorporate wind power forecasts in the scheduling decisions, wind curtailment is minimal even with low levels of interconnection. As would be expected an increase in interconnection should improve system adequacy considerably with a significant reduction in the number of hours when the load and reserve constraints are not met.     

Proliferation of district heating using local energy resources through strategic building-stock management: A case study in Fukushima,Japan

District heating systems using cogeneration technology and renewable resources are considered as an effective approach to resources conservation and reduction of greenhouse gas (GHG) emissions. However, widespread aging and depopulation problems, as well as the popularization of energy-saving technologies in buildings, are estimated to greatly decrease energy consumption, leading to inefficiency in district heating and barriers to technology proliferation. From a long-term perspective, land use changes, especially the progression of compact city plans, have the potential to offset the decrement in energy consumption that maintains the efficiency of district heating systems. An integrated model is developed in this paper based on building cohort analysis to evaluate the economic feasibility and environmental impact of introducing district heating systems to a long-term compact city plan. As applied to a case in the Soma Region of Fukushima, Japan, potential migration from the suburbs to the central station districts is simulated, where district heating based on gas-fired cogeneration is expected to be introduced. The results indicate that guided migration to produce concentrated centers of population can substantially increase the heat demand density, which supports a wider application of district heating systems and better low-carbon performance. These results are further discussed in relation to technology innovation and related policies. It is concluded that policies related to urban land use planning and energy management should be integrated and quantitatively evaluated over the long-term with the aim of supporting urban low-carbon sustainable development.     

Prediction,potential and control of plume from wet cooling tower of commercial buildings in Hong Kong: A case study

This paper presents a case study of the prediction, potential and control of plume in wet cooling towers from a huge commercial building in Hong Kong based on the weather data available for a particular year. The power input is found to be lower and the coefficient of performance (COP) moderate when all the 10 towers with low speed are in use, while it is found to be reverse when there are five towers, especially, three low and two high‐speed towers are used. It is also found that the combined heating and cooling option can be a better approach than that of the heating option alone from the point of view of thermodynamics as well as from the point of view of economics. The COP of the chillers increases from 6.01 to 7.09 when the number of cooling towers increases from five to ten. On the other hand, the power consumption first decreases and then increases which is mainly due to the increment in the consumption of fan power from 270 to 900 kW for both options. The overall power consumption decreases slightly for the combined heating and cooling option, while in the heating option, the overall power consumption increases slightly. However, it is observed that a proper operation of cooling towers is an effective means to control and/or at least reduce the potential of visible plume generated by wet cooling towers at the existing chilling plant design for this particular building. Copyright © 2006 John Wiley & Sons, Ltd.     

Analysis of a pumped storage system to increase the penetration level of renewable energy in isolated power systems. Gran Canaria: A case study

A significant number of islands have been forced to restrict the penetration level of renewable energy sources (RES) in their conventional electrical power systems. These limitations attempt to prevent problems that might affect the stability and security of the electrical system. Restrictions that may apply to the penetration of wind energy can also be an obstacle when meeting European Union renewable energy objectives. As a partial solution to the problem, this paper proposes the installation of a properly managed, wind-powered, pumped hydro energy storage system (PHES) on the island of Gran Canaria (Canary Islands). Results from a dynamic model of the island’s power system show that the installation of a pumped storage system is fully supported in all circumstances. They also show that the level of wind penetration in the network can be increased. These results have been obtained assuming that two of the largest existing reservoirs on the island (with a difference in altitude of 281 m and a capacity of aprox. 5,000,000 m³ each) are used as storage reservoirs with three 54 MW generators. Likewise, the ability of such facilities to contribute to the stability of the system is shown. This type of installation can reduce fossil fuel consumption, reducing CO₂ emissions. Moreover, not only can the PHES improve wind penetration level, but it also allows the number of wind farms installed to be increased. Regions with geographically suitable sites and energy problems similar to those on the Canary Islands are encouraged to analyze the technical and economic feasibility of installing similar power systems to the one in this paper. Such systems have an enormous, unexplored potential within the general guiding framework of policies promoting clean, renewable energy.     

Allocation and sizing of battery energy storage system for primary frequency control based on bio-inspired methods: A case study

This paper presents a new procedure for optimal allocation and optimal sizing of a battery energy storage system (BESS) for primary frequency support in an isolated power system. For the BESS allocation, a transmission bus system with larger frequency decline is recognized and the BESS sizing is performed by a constrained optimization strategy based on a new modified metaheuristic, called Developed Harris Hawks Optimization (DHHO). The simulation results of the suggested DHHO are compared with Bat Optimization Algorithm (BOA) and Genetic Algorithm (GA) from the literature to show the method efficiency. The final results showed higher precision with lower required iterations for the suggested DHHO method. Also, the proposed DHHO gives lower investment costs for BESS with lower power and energy requirement toward the other compared methods.     

Prospects and economic feasibility analysis of wind and solar photovoltaic hybrid systems for hydrogen production and storage: A case study of the Brazilian electric power sector

The work aims to verify the economic feasibility of renewable hybrid systems for hydrogen production and storage in the Brazilian electric power sector. The methodology applied is based on economic cost analyses of the two largest wind and solar photovoltaic plants in the country. As a result, the number of hours of electricity available for hydrogen production directly influences its cost. However, fully dedicated plants to produce green hydrogen have shown economically feasible to the exporter or other sectors, being trading hydrogen is more profitable than transforming it back into power. The model also concludes that wind and solar hybrid systems for hydrogen production and storage are still not economically viable in Brazil. The CAPEX of electrolysers and their operating losses are still very significant. Finally, hydrogen production and storage become economically feasible only from plants operating above 3000 h and for electrolysers with a CAPEX of USD 650/kWe.