Coordination between clean energy generation and thermal power generation under the policy of “direct power-purchase for large users” in China

The inefficient utilization of clean energy and distorted pricing mechanism are the most critical problems that have hampered the reform of China's electric power industry for many years. A large number of clean energy generators have recently been constructed, but water spillage at hydroelectric facilities and wind curtailment persist due to integration challenges. The adjustment of electricity price has relied on executive orders of the Chinese government and the National Development and Reform Commission (NDRC). Distorted prices that are not derived from a market economy have seriously hampered the development of China's electricity market. Therefore, in recent years, the Chinese government has issued a number of reform measures concerning “direct power-purchase for large users”. The main idea of this pricing mechanism is to form direct negotiations between large users and generators to determine the electricity price. To a certain extent, this pricing mechanism is conducive to the electricity market reform in China. However, the coordination between clean energy generation and thermal power generation under the policy of “direct power-purchase for large users” has become the key issue in China's electric power industry. This paper summarizes the policies of “direct power-purchase for large users” in different provinces in China. The electricity market in Yunnan, for which the contradiction between thermal power generation and hydropower generation is increasingly severe, is the focus of the research. At last, a feasible electricity market scheme has been derived to coordinate thermal power generation and hydropower generation. This scheme has considerable theoretical and practical significance to the future of China's electricity market reform.     

Does the Ukrainian electricity market correspond to the european model?

The paper explores 29 models of the European electricity markets and the degree of their deviation from the single electricity market model established by the trans-European legislation. Although all models correspond to the design of the pan-European single one, they remain significantly differentiated according to trading forms and pricing methods. The electric power system in Ukraine has developed oppositely to the European ones, and the electricity market is quasi-competitive. The study proposes a novel model for the Ukrainian electricity market, which considers the European acquis communautaires, the advanced practice in electricity market development, and the specifics of the Ukrainian electric power system.     

Reply to Discussion on “Analysis of Bingham fluid radial flow in smooth fractures”

Recently, Hoang et al. (2021) discussed our paper Zou et al. (2020). In our paper, we made a statement that Dai and Bird (1981)'s solution for two-dimensional (2D) radial Bingham fluid flow between parallel plates violates mass balance. Hoang et al. pointed out that Dai and Bird (1981)'s solution does not violate the mass balance because Dai and Bird (1981)'s solution and our analysis are based on different assumptions, i.e. with consideration of the vertical velocity component in the continuity equation or not, which leads to two different approximation models. In this sense, the mass balance of Dai and Bird (1981)'s solution should not be checked using our solution as a reference. In this reply, we add remarks on the two approximation models and their implication for rock grouting analysis. The discussion by Hoang et al. and this reply are helpful to thoroughly eliminate the existing confusion regarding the two solutions in the rock grouting research community.     

Customer response to day-ahead market hourly pricing: Choices and performance

Real-time pricing (RTP) has been advocated to address extreme price volatility and market power in electricity markets. This study of Niagara Mohawk Power Corporation's largest customers analyzes their choices and performance in response to day-ahead, default-service RTP. Overall price response is modest: 119 customers are estimated to reduce their peak demand by about 10% at high prices. Manufacturing customers are most responsive with a price elasticity of 0.16, followed by government/education customers (0.11), while commercial/retail, healthcare and public works customers are, at present, relatively unresponsive. Within market segments, individual customer response varies significantly.     

Standardizing the Measurement of Minimum Extinguishing Concentrations of Gaseous Agents

The cup-burner test method has had a long history as a tool for measuring the minimum flame extinguishing concentrations (MEC) of gaseous fire-extinguishing agents for flammable and combustible liquid fuels. The pioneering work by Hirst and Booth (1977) set out the basic principles of the cup-burner and its use. Saso et al. (1993) reported on scale effects on MEC measurement. Preece et al. (2003) reported on parametric effects on MEC measurement. A number of investigators have provided determined values of MEC for a number of inert gas and fluorocarbon agents. See Dlugogorski et al. (1996); Saito et al. (1996); Moore et al. (1998); Sheinson et al. (1998). Takahashi et al. have reported on several investigations of flame extinguishment in the cup-burner including conducting a detailed computational fluid dynamic modeling including reaction kinetics and mass and heat transfer (2003); physical and chemical aspects of flame extinguishment (May 2005); and evaluation of flame extinguishment in low gravity (January 2005). Application of the cup-burner method has, in some instances, produced inconsistent results. MEC values reported by several investigators for the same inert gas agents have exhibited differences that are significant with respect to the way in which they are used (Senecal 2005). Thermochemical analysis and data obtained in a consistent manner suggested that there is a reasonable basis to expect highly consistent, and even predictable, MEC values for inert gas agents. It appeared that the likely source of measurement variation was due to procedural and mechanical differences in the conduct of the cup-burner test among various laboratories. A Task Group, appointed by the NFPA GFE-AAA technical committee on gaseous fire-extinguishing systems, revised the cup-burner test procedure including the specification of a standardized test apparatus. This article describes an inter-laboratory study conducted in 2006 to (1) determine consensus value benchmark minimum extinguishing concentrations (MEC) of an inert gas agent and a halocarbon agent; (2) evaluate the reproducibility of the revised test method; and (3) evaluate the day-to-day consistency (repeatability) of the test method. The results of an inter-laboratory (round robin) study have established benchmark MEC values for nitrogen and HFC-227ea with excellent reproducibility. The results show that MEC values reported by most laboratories were in very good agreement, i.e., exhibited good reproducibility based on averages of three replicate determinations on different days. Analysis of the replicate data revealed a variable degree of repeatability, suggesting that a laboratory will need to review key procedural details in some cases.

Market power in California electricity markets

As the electricity industry in California undergoes a process of fundamental restructuring, important new products and markets will be created while others will lose significance. In this paper, we undertake an initial survey of the products and markets that will be prominent in the emerging new electricity industry. We describe approaches to analyzing the prospects for, and the impacts of, market power abuse in these various product markets. The key product markets that are discussed include those for spot electrical energy, for pool-based and physical power contracts, and for reliability services such as load balancing and spinning reserve. Structural measures of market power, such as the Hirschman-Herfindahl Index (HHI), have certain general shortcomings that are exacerbated when applied to restructured electricity markets. Fortunately, the direct estimation of competitive equilibria, such as a Cournot oligopoly equilibrium, appears to be more feasible for this industry than is generally the case.     

An integrated model for electricity market coupling simulations: Evidence from the European power market crossroad

Motivated by the project of European Power Exchanges to develop a single price-coupling solution to calculate electricity prices across Europe that respects the cross-border capacity constraints on a day-ahead basis, we empirically examine and quantify market inefficiencies in non-coupled day-ahead electricity markets. These result from inefficient cross-border capacity allocation and its underlying effect on the market clearing prices. Efficient cross-border capacity allocation and new market clearing prices are simulated using a social welfare maximisation algorithm for the capacity of relevant network elements, whereas the order book generation process is reproduced by the econometrically estimated supply price elasticity functions. The estimated vector autoregression model and the underlying impulse response functions examine price shock transmission under different market regimes. The market coupling process is simulated on the historical non-coupled day-ahead market realisations at the junction of three regional power markets: Central Western Europe, Northern Italian, and South Eastern European markets. Simulation results confirm steady, efficient cross-border capacity utilisation, reduced price variance, improved overall price convergence and amplified price shock transmission in coupled electricity markets. Furthermore, in the simulated period, we have estimated an increase in the overall suppliers' and consumers’ surplus of almost EUR 16 million. The proposed simulation framework is a clear choice for applied simulation in coupled day-ahead electricity markets, offering valuable visual insights into the cross-border capacity allocation and its implications on electricity prices.     

Transmission pricing and investment incentives

The allocation of limited transmission resources has considerable impact on investment incentives in electricity markets. We study the long–term effects of two common network congestion management regimes on investment in production and transmission facilities. We compare locational marginal pricing, where transmission constraints are directly taken into account by spot–market prices, with a regime of uniform prices, where transmission constraints are taken into account by subsequent congestion measures. We propose an analytically tractable framework to show that, as compared to locational marginal pricing, uniform pricing can lead to overinvestment in transmission facilities and total production capacities.     

Optimal time for implementing cordon toll pricing scheme in a monocentric city

This paper proposes an analytical model to address the timing issue of cordon toll pricing in a monocentric city. The proposed model allows an explicit consideration of the interactions among three types of agents in the urban system: (i) the local authority who aims to jointly determine the optimal time for introducing cordon toll pricing scheme, cordon toll location and toll level to maximize social welfare of the urban system; (ii) property developers who seek to determine the intensity of their capital investment in the land market to maximize their own net profit generated from the housing supply; and (iii) households who choose residential locations that maximize their own utility within a budget constraint. The effects of the cordon toll pricing scheme on household's residential location choice and housing market structure in terms of housing price and space are explicitly considered. A comparison of the toll pricing schemes with a fixed and a mobile cordon location over time and the no toll case is carried out. The proposed model is also illustrated in several Chinese cities. Insightful findings are reported on the interactions among cordon toll pricing scheme, urban population size, household income level, toll collection cost, and urban development.     

Consumer preferences and electricity pricing reform in Western Australia

Australia's electricity prices are high, driven by rising peak demand that is forcing significant levels of infrastructure investment. Compounding these factors is the lack of transparent price signals for consumers, with uniform pricing structures providing no incentive to change consumption behaviours.This research surveyed residential electricity consumers in Western Australia about their perceptions of solar, consumption behaviour, and electricity pricing structures.The results suggest that customers in Western Australia may be willing to change behaviour, reduce electricity usage, and be rewarded for use of renewable technologies, highlighting an opportunity for policies such as retail tariff reform to be further explored.     

Discussion on “Impact of orientation of blast initiation on ground vibrations” [J Rock Mech Geotech Eng 15 (2022) 255–261]

Recently, Garai et al. (2022) published a paper on the impact of orientation of blast initiation on ground vibrations. However, some of the claims are not supported by the results of the given tests. In Fig. 1 (see Fig. 8 in Garai et al., 2022), there are contours of measured vibration velocities in 4 directions (every 90°) and an incorrect interpretation between them. By placing all measured vibration velocity values (Gerai et al., 2022) at well-defined points on a single figure, it was not possible to precisely determine the type of vibration velocity, such as radial, tangential and vertical vibration velocities, with their different shapes. An incorrect conclusion was also drawn about the direction of the highest vibration velocity. The paper by Garai et al. (2022) measured the vibrational velocity of the medium through which the seismic wave passed, but used the incorrect term shock wave. The shock wave would have destroyed the seismic measuring instruments. A superposition of the vibrational velocity was considered, but not combined with the vibrational frequency of the seismic wave. This paper presents a method for selecting the time delay between successively initiated explosive charges to the measured frequency of the seismic wave, so that the direction of initiation of the explosive charges does not affect the vibration velocity of the ground through which the seismic wave passes. The theoretical and measured shapes and waveforms of radial velocity and tangential velocity in an opencast lignite mine are then presented. Moreover, the conditions for the formation of shock wave, transition wave and seismic waves are presented.     

Design of regional flexibility markets for electricity: A product classification framework for and application to German pilot projects

With the growing role of distributed energy resources, the electricity network is challenged by numerous technical problems, such as capacity congestion and over- or under-voltage. An often-discussed response, especially in the European zonal electricity system, is to implement regional flexibility markets. We contribute to this discussion by providing a comprehensive classification framework for the design of flexibility products by combining technical requirements with classical auction theory. The framework structures 23 product parameters in four stages of abstraction. By applying the framework to five market approaches used in current German research projects, we demonstrate its usefulness for consistent comparison of flexibility products at a high level of detail. This framework can empower national and international policymakers and practitioners in assessing flexibility markets holistically, thereby facilitating the implementation of sound solutions.     

Electricity price forecasting using neural networks with an improved iterative training algorithm

In a competitive electricity market, the forecasting of energy prices is an important activity for all market participants either for developing bidding strategies or for making investment decisions. In this article, a new forecasting strategy is proposed for short-term prediction of the electricity price, which is a complex quantity with nonlinear, volatile and time-dependent behaviour. Our forecast strategy includes two novelties: a new two-stage feature selection algorithm and a new iterative training algorithm. The feature selection algorithm has two filtering stages to remove irrelevant and redundant candidate inputs, respectively. This algorithm is based on mutual information and correlation analysis. The improved iterative training algorithm is composed of two neural networks in which the output of the first neural network is one of the inputs to the second. The overall proposed strategy is applied to the Pennsylvania–New Jersey–Maryland (PJM) electricity markets and compared with some of the most recent price forecast methods.     

The impact of renewable energy on household electricity prices in liberalized electricity markets: A cross-national panel data analysis

The main research questions addressed in this paper are: first, have electricity market reforms achieved lower household electricity prices and, second, has the introduction of renewable energy increased household electricity prices in deregulated markets Answers to the questions were derived using static and dynamic panel data analysis from 1991 to 2014 employing explanatory variables such as the extent of electricity market reform and the share of generation from renewable energy resources. The dynamic model suggests that a lower household electricity price is associated with the degree of electricity market reform, while the share of renewable energy in electricity generation is not statistically significant.     

Three-part auctions versus self-commitment in day-ahead electricity markets

We examine the economic consequences of a bid-based security-constrained centralized unit commitment paradigm based on three-part offers, which is the prevalent day-ahead market-clearing mechanism in restructured electricity markets in the United States. We then compare this approach with an energy-only auction with self-commitment (such as in Australia) addressing efficiency and pricing as well as the tradeoff between coordination losses and incentives to bid truthfully.     

Environmental policy and electricity spot markets

A change in the operation of electricity systems as profound as a move to spot pricing will alter the ground-rules for the environmental regulation of such systems. The change will also affect the decisions made by utility managers and consumers, which will modify the impact that electricity generation and consumption has on the environment. In the light of pressing global environmental problems, the opportunities and problems which spot market operation bring and the place of pricing reform in an overall environmental strategy are discussed.     

Generation adequacy: Helping the market do its job

In response to concerns that competitive electricity markets may be subject to the development of an investment cycle, a number of adjustments to the market structure have been proposed for stabilizing investment in generating capacity. This paper reviews the advantages and disadvantages of these capacity mechanisms and presents a policy framework for selecting the most suitable capacity mechanism. The choice of capacity mechanism depends upon circumstances such as whether the market in question has a mandatory power pool and whether it is strongly interconnected to other markets. This analysis focuses specifically upon options for European markets, which typically are of the decentralized type (without mandatory power pools) and have significant exchanges with neighboring markets. These two factors complicate the implementation of a capacity mechanism.     

Electricity sector reform in Greece

This paper provides an outlook of the electricity market reform in Greece which started in 2001 and is still developing slowly. This is related to the persisting dominance of the incumbent company and the specificities of the electricity sector of Greece which is heavily dependent on indigenous lignite firing generation, while being located in the periphery of the EU internal electricity and gas markets. Competition through enhancing electricity trade in the region is limited to date, as the establishment of an internal market in South East Europe also progresses slowly. Development of competition through gas-firing generation by new entrants has been the priority adopted by State and Regulator's policies. However, the gas supply market in Greece and in the region still lags behind.