Electricity Purchase Research Articles

Liquefied biomethane from sugarcane vinasse and municipal solid waste: Sustainable fuel for a green-gas heavy duty road freight transport corridor in Sao Paulo state

Diversifying the energy components of a country's transport sector is essential to guarantee the fuel supply to consumers and increase the market dynamics and competitiveness. Among the known alternative fuels, biogas is a renewable source and after upgrading to biomethane, it presents a similar composition to natural gas (>90% of CH4; 35–40 MJ m−3). In addition, it can be produced from a wide variety of biological resources and at different scales In this study, two scenarios have been developed that evaluate the use of liquefied biomethane (LBM) as a diesel replacement option in the freight sector of an area of 248,223 km2 (equivalent to the area of the UK). Sugarcane vinasse (SVC) and Municipal Solid Waste (MSW) were the sole feedstocks for biogas production. The first scenario, non-restricted scenario (NRS), covered the entire territory while, the second scenario, restricted scenario (RS), includes only the area where gas pipelines are available. An economic assessment of the entire biogas value chain including, biogas production units, purification, transport and end-use was performed. The minimum selling price (MSP) of biomethane throughout the biogas chain was then estimated. LBM is estimated to be a cost-effective and affordable fuel choice compared to diesel. The technical potential of biogas production by the sugarcane mills and landfills of Sao Paulo state can replace up to half of the diesel consumed in the territory. The minimum distances and optimal locations methodology indicated the need for 120 liquefaction plants in the NRS, 35 injection points in the RS, and 7 refuelling stations to supply LBM throughout the state of Sao Paulo. The units for CO2 removal had the greatest influence on capital costs (∼60%) in both scenarios. Expenditure associated with the gas injection operation and its transport comprised more than 90% of the operating costs of the RS. Electricity purchasing represented the highest share of the operating costs at biogas purification (20%–30%) and biomethane liquefaction (65%–91%) units. Personnel costs are observed along the entire biogas chain, especially, in the biomethane transport step (40%), indicating an opportunity to generate wealth, jobs, and income. Despite our projections for the cost-effective and competitive supplies of LBM as a diesel replacement fuel, policy support measures such as a feed-in tariff, are likely to be necessary in order to overcome non-technical barriers and gain wider acceptability.

Operation Mode of Integrated Energy System with Liquid Air Energy Storage

This paper takes the energy supply in the park as the research background, the integrated energy system as the research object and establishes the integrated energy system model including liquid air energy storage, distributed photovoltaic, gas turbines and other equipment. When the integrated energy system operates the mode of “ordering heat by power”, the heat wasted as high as 14.647MWh and the cold wasted as high as 24.13MWh. When the system is not equipped with LAES, the output power of the CCHP unit increases by 21MWh, the electricity purchase in power grid increases by 8.123MWh, the heat waste increases by 21.696MWh and the cold waste increases by 12.421MWh. When the integrated energy system operates the mode of [[CHECK_DOUBLEQUOT_ENT]] ordering power by heat ", heat energy of the system has been reasonably utilized. When the system is not equipped with LAES, the power output and heat of the CCHP unit in the system are the same, the thermal energy output results of the system are the same and the electricity purchased by the power grid increases by 32.14MWh.

Modeling the Proposal of the Simultaneous Purchases and Sales of Electricity and Gas for the Energy Market in a Microgrid Using the Harmony Search Algorithm

The use of different energy carriers together, known as an energy hub, has been a hot topic of research in recent years amongst scientists and researchers. The term energy hub refers to the simultaneous operation of various infrastructures for energy generation and transfer, which has gained momentum in the form of microgrids (MGs). This paper introduces a new strategy for the optimal performance of an MG consisting of different energy carriers for each day. In a smart distribution network (DN), MGs can reduce their own costs in the previous-day market by bidding on sales and purchases. The sales and purchases bidding problem is challenging due to different uncertainties, however. This paper proposes a two-stage strategy for making an optimal bid on electricity sales and purchases with electricity and gas price dependency in the previous-day and real-time markets for an energy hub. In this model, the MG behavior regarding the electricity and gas energy sales/purchase, the simultaneous effects of electricity and gas prices, as well as the energy carriers’ dependence on one another are all examined. Due to the inherent uncertainty in the sources of clean energy production, the probabilistic model and the production and reduction scenario have been used in the paper to cover this issue. In the proposed grid, energy sales/purchases are presented in a multi-carrier MG in a two-stage model. This model is solved by using the harmony search algorithm in MATLAB. Numeric results demonstrate the benefits of this model in reducing energy hub costs of operation.

Efekti izgradnje FN elektrana u proizvodnim pogonima Rudnika uglja "Kreka" u Tuzli

The use of renewable energy sources is imposed as an imperative for the competitiveness and stable energy policy of companies. The basic production equipment in the "Kreka" coal mine in Tuzla has electrical plants with a total peak load of 12 MW, and the costs for electrical energy exceed €3.5 million annually. The paper analyzes the suitability of infrastructure facilities and devastated areas of the Kreka Coal Mine in Tuzla for the construction of photovoltaic power plants and the effects of such plants. The results of the analysis show a significant resource for the installation of photovoltaic power plants with a capacity of 230 MW. The production of electricity from these photovoltaic power plants enables a reduction of emissions into the air by 190 t/year of particle emissions, by 316.2 •103 t/year of CO2 emissions, by 58.15 t/year of SO2 emissions and by 251.9 t/year of emissions NOx. With the subsidized purchase of electricity, it is possible to return the investment within 6 years.

Net-Metering vs. Net-Billing from the Investors Perspective—Impacts of Changes in RES Financing in Poland on the Profitability of a Joint Photovoltaic Panels and Heat Pump System

The paper explores the impacts of changes in renewable energy sources (RES) financing in Poland on the profitability of coupled photovoltaic panels and heat pump systems. The profitability analysis is conducted with the use of Net Present Value calculation and the return on investment period. The degree of change in profitability of using photovoltaic panels in Poland is dependent on the method of their financing. The analysis is carried out for two different photovoltaic support schemes: (1) the net-metering scheme currently in force in Poland; (2) the net-billing system scheduled for implementation in the year 2022. It is assumed for the analysis that two alternative heating and electricity supply systems for a single-family building will be operated: (a) a standard solution used in Poland consisting of a natural gas-fired boiler for heating and the purchase of electricity from the power grid, (b) an air/water heat pump used to heat the building, and electricity obtained from photovoltaic panels, also used to power the heat pump. A sensitivity analysis is carried out, examining the impact of several key parameters relevant for the profitability of such investments, such as average annual increase in the purchasing or selling prices of electricity, purchasing prices of natural gas, and inflation rate. The conclusions concern the possible consequences of introducing a new support scheme for photovoltaics in Poland. The highest profitability of all considered solutions is for the current scenario for heat pump and pv installation with the capacity to meet the demand in the last year of operation. The introduction of changes in the new RES law (2021) in Poland will reduce the profitability of investments in pv panels, leading to a slowdown in the investments in the pv installations.

WHOLESALE MARKET OF ELECTRICITY AND POWER AS RESULT OF RAO UES REFORM (ON THE EXAMPLE OF ALTAI KRAI)

The article examines the specific structures and mechanisms of power supply to consumers that have developed as a result of the so-called market transformations of RAO UES of Russia. Reforms, conceived as market reforms, in fact, ended up as a conglomeration of administrative and bureaucratic structures and certain principles, rules and procedures that vaguely resemble market relations. In fact, the transformation of the electric power industry was forced to take into account the anti-market nature of its functioning: first, technological (specificity of the product and the industry); second, organizational and administrative, requiring a special organization, which is fundamentally different from the traditional market for goods and services. Therefore, the transformation of the electric power industry, carried out by the method of trial and error, has gone through a rather difficult path of registration, re-registration, change of the legal status of market participants. Almost all the processes of buying and selling electricity and capacity are surrounded by numerous rules, restrictions, institutions that have nothing to do with the market. This concerns the choice of counterparties, electricity payment processes and especially capacity, when the consumer pays in advance for the goods that were not actually purchased from the supplier.

PRICE DISCIMINATION IN THE ELECTRICITY MARKET OF UKRAINE

The article is devoted to the problem of price discrimination in the electricity market of Ukraine. The article reveals the essence and degree of price discrimination in the market of production, transmission and distribution of electricity. It is determined that electricity is a standardized product but has a number of features that significantly affect the formation of costs for its production. During the sale, electricity has several prices, which indicates monopoly in the market and the existence of price discrimination. It is analyzed that price discrimination allows market participants to receive higher profits, but for the use of the price discrimination system several important conditions must be fulfilled: concentration of market power; the possibility of differentiation of counterparties; impossibility of resale of goods. It is investigated that the electricity market of Ukraine is characterized by discriminatory pricing of the third degree to a greater extent, and the second – to a lesser extent. It was found that price discrimination concerning producers is represented by different generation of electricity and different purchase prices: thermal, hydro, nuclear, block stations, RES (renewable energy sources). Regarding consumer discrimination, the most common is price discrimination based on day and night prices – this is due to the specifics of electricity generation and consumption – during the day the load on the network is greater due to business, at night consumption falls, but most power plants can not stop generation, therefore, they reduce it to a minimum and still have an excess of electricity. Different electricity tariffs for household and non-household consumers provoke cross-subsidization. Cross-subsidization in electricity is understood as price discrimination: electricity tariffs for industrial and commercial consumers are set above the marginal cost, and for households – lower, so the former are forced to overpay and subsidize the latter. There is a separate price discrimination based on geographical location: for the population living in the 30-kilometer zone of nuclear power stations, distribution of electricity is supplied at a rate of 70 percent of the current tariff for the specific group of population. The consequences of price discrimination are analyzed. High tariffs for businesses translate into higher costs for the production of goods and, consequently, higher wholesale and retail prices for consumers. The social effect of subsidizing the sale of electricity prices for the population is thus largely graded. In our opinion, a number of measures, which have been proposed, are aimed at demonopolizing the electricity market in Ukraine and reducing the level of price discrimination.

Framework and Key Success Factors of Governance and Sustainability of Very Small Municipal Solid Waste Power Plants

Inordinate municipal solid waste issues and ever increasing demand for electricity, the Thai government formulated the Power Development Plan focusing on supporting the use of renewable energy to generate electricity and using measures to promote the purchase of electricity from very small power producers. This support indubitably leads to the question as to whether Very Small Municipal Solid Waste Power Plants (VSMSWPPs) are sustainable or not. Thus, this study aims to develop a framework and key success factors for evaluating governance and sustainability of VSMSWPPs in Thailand. It consists of documentary research and interviews with professionals, policy makers, practitioners and power plant owners conducted to develop the framework and determine the key success factors. Subsequently, the framework and factors were assessed by 12 experts. The good governance and sustainability concepts were selected as a framework and used to construct key success factors to evaluate the performance of VSMSWPPs. The framework contains four dimensions and each dimension had key success factors as follows: (1) Governance dimension with 7 key success factors; (2) Economic dimension with 8 key success factors; (3) Social dimension with 5 key success factors; and (4) Environmental dimension with 7 key success factors: at total of 27 key success factors.

A Comprehensive Game Theoretical Defense Strategy in Demand Side Management Against Price Tampering Attacks

Price tamping attacks may cause market turbulence, attack detection and defense strategy are needed to study. Firstly, demand response characteristics are analyzed in a User Energy System. A quantitative model is established to describe the load changes caused by price tampering attacks. Secondly, a space-based cumulative intrusion detection method is proposed to pick up the discrepancy under tampering attacks. To verify the practicability of the proposed method, intrusion detection experiments are tested in the Principal Information and Safety Laboratory. Then, comprehensively considering the purchase of electricity from the power grid, self-generation, and load shedding, a quantitative model of attack consequences is established based on the allocation coefficient. Thus, the intrusion detection algorithm is used as a defense resource, and a demand-side defense protection strategy is formed to find an optimal deployment method based on non-cooperative game theory. The defensive protection strategy takes the quantitative model of attack consequences as the solution target, and solves the Nash equilibrium solution under different attack modes. Finally, in the IEEE-33 node system simulations, the defense resource is deployed using intrusion detection strategy, and the defense decision is executed to show the effectiveness of the comprehensive protection strategies.

Integration of photovoltaic and hydrogen fuel cell system for sustainable energy harvesting of a university ICT infrastructure with an irregular electric grid

This study investigates the prospect of using an integrated renewable power system to enhance an unreliable grid network for sustainable electricity generation. A grid coupled microgrid comprising photovoltaic and hydrogen fuel cell system, simulated for an information and communication technology (ICT) building is considered. The overall objectives are to decide the technical, ecological and monetary gains of the addition of green energy sources to an unreliable grid for electricity harvesting within university campuses. The energy-balance procedures of the hybrid optimisation model for electric renewables software tool are employed for this study. The system design is implemented for the electrical load of an ICT building at Ambrose Alli University (6°44.0′N, 6°5.1′E) using long-term meteorological datasets collected for the study site. The results show that the integration of 323 kW photovoltaic array, 75 kW power converter, and 25 kW fuel cell system with 26 kW electrolyser and 20 kg hydrogen tank can reliably enhance the existing unreliable electric grid system in a clean and sustainable way. Using this integrated energy system requires an initial capital ($ 247,100), net present cost ($ 445,266), yearly operating cost (3,901 $/y), and cost of energy (0.05976 $/kWh). Consequently, the renewable fraction increases by 91.2%, CO2 cut by 95.2%, while the grid electricity purchases reduce by 80.7%, at a cost saving of 91.6%.

Network Externality and Subsidy Structure in Two-Sided Markets: Evidence from Electric Vehicle Incentives

This paper uses new, large-scale vehicle registry data from Norway and a two-sided market framework to show nonneutrality of different subsidies and estimate their impact on electric vehicle adoption when network externalities are present. Estimates suggest a strong positive connection between electric vehicle purchases and both consumer price and charging station subsidies. Counterfactual analyses suggest that between 2010 and 2015, every dollar spent on station subsidies resulted in more than twice as many additional electric vehicle purchases than the same amount spent on price subsidies. However, this relation inverts with increased spending, as station subsidies’ impact tapers off faster. (JEL D12, D62, D85, H25, L62, Q54)

Multivariate analysis of the influence between building design and energy performance, socio-demographic metrics, and the intra-urban environment

Through advancements of direct and remote sensing technologies, we have recently learned that urban microclimate and air quality gradients can often be more significant than city to rural differences. However, the urban design parameters that are most critical to improve environmental health and reduce building energy consumption, are yet to be identified. This research makes use of air quality datasets collected through a dense stationary sensing network in New York City, remote sensing datasets for land surface temperature and normalized difference vegetation index, building usage metrics, building and urban design metrics, and socio-demographic datasets including population and health metrics. Through a neighbourhood-scale footprint-based regression analysis, the correlation between the air quality, land surface temperature, building usage and urban metrics has been studied. Highest correlations have been observed between air quality and land surface temperature and urban design and socio-economic metrics. The results show that building usage metrics such as the energy use intensity or electricity purchase, are mainly affected by building design characteristics. On the other hand, significant correlations have been observed between the urban design, socio-demographic and contaminant concentration gradients, addressing the critical role the planning and design of our cities plays in the environmental well-being of citizens.

The New Investment Cycle: Current Finance Mechanisms of Power Engineering Development

The article provides the analysis of current finance mechanisms of developing power systems in the context of acute necessity to start a new investment cycle. It draws a conclusion that state policy in the field of power engineering cannot foster the development of such mechanisms of its financing as state subsidies on purchase and installation of equipment, contracts on buying electricity and power-service contracts. The analysis of extra opportunities of raising investment showed expediency of developing green mechanisms of financing power engineering in Russia and motivating power companies to conduct IPO. The authors put forward recommendations aimed at attaining the acute objective to develop and implement key initiatives promoting the start of a new investment cycle in order to raise funds for modernizing the existing power projects and opening new ones in accordance with higher ecological requirements. For example, to stimulate the growth of Russian companies' IPO and realize the investment potential of the Russian stock market the Central Bank of the Russian Federation and the Ministry of Economic Development study the possibility to introduce new tax preferences for investors and companies entering the market, which could ensure institutional support for investors and issuers.

Cost-Benefit Analysis of Small-Scale Rooftop PV Systems: The Case of Dragotin, Croatia

A large drop in prices of photovoltaic (PV) equipment, an increase in electricity prices, and increasing environmental pressure to use renewable energy sources that pollute the environment significantly less than the use of fossil fuels have led to a large increase in installed roof PV capacity in many parts of the world. In this context, this paper aims to analyze the cost-effectiveness of installing PV systems in the rural continental part of Croatia on existing family houses. A typical example is a house in Dragotin, Croatia with an annual consumption of 4211.70 kWh of electricity on which PV panels are placed facing south under the optimal slope. The calculation of the optimal size of a PV power plant with a capacity of 3.6 kW, without battery energy storage, was performed by the Homer program. The daily load curve was obtained by measuring the electricity consumption at the facility every hour during a characteristic day in the month of June. As most of the activities are related to electricity consumption, repeating during most days of the year, and taking into account seasonal activities, daily load curves were made for a characteristic day in each month of the year. Taking into account the insolation for the specified location, using the Internet platform Solargis Prospect, hourly data on the electricity production of selected PV modules for a characteristic day in each month were obtained. Based on the previous data, the electricity injected into the grid and taken from the grid was calculated. Taking into account the current tariffs for the sale and purchase of electricity, investment prices, and maintenance of equipment, the analysis shows that such a PV system can pay off in 10.5 years without government incentives.

Priority power generation allocation method for reservoir power stations based on the priority index

China may require a long time to transition its power system from a planned one to a completely competitive market. Priority power generation (PPG), as a special type of power in the transitional period, is of great importance to incentivise power generation entities to participate in the market and promote power system reforms. However, the allocation of PPG currently relies excessively on the subjective decisions and experience of staff and lacks scientific basis and reasonable methods. Considering the case of Sichuan Province in China, this study proposed a PPG allocation method for reservoir power stations (RPSs) based on the principles of fairness, justice, and openness. First, RPSs were divided into categories based on the clustering results of many variable indicators that reflect the contribution and cost in aspects such as power generation, flood control, water supply, irrigation, emission reduction, grid peak shaving. Second, the random forest method was adopted to select the key indicators affecting the classification results. Then, the key indicators were weighted to obtain the priority index, and the PPG allocation was performed based on the priority index. Finally, the proposed method was used to allocate the PPG of RPSs in Sichuan in 2019. The results indicated that the allocation method based on the priority index is more conducive to increasing the market participation of RPSs than the original plan. In addition, it can save approximately 73 million yuan in electricity purchase costs for the grid.

Integrated design and operation of energy systems for residential buildings, commercial buildings, and light industries

This work introduces an optimization approach for the design and operation of integrated energy systems of residential structures and light industrial plants to minimize greenhouse gas (GHG) emissions going beyond the best possible results from standalone systems. Unlike previous studies, in this work, heat transfer considers temperatures of heat sources and receptors; production rates of plants are optimized to maximize GHG emissions reduction of the integrated operation. Results from case studies indicate if temperature levels are not considered, more than 33% of deemed heat transfer is infeasible. Operating the integrated plants at a steady daily production rate brings a significant reduction in GHG emissions for systems accessing the northeast U.S. grid. Further reduction of GHG emissions is accomplished by scheduling the production rate. Schedules with at most one daily production rate change have only 0.4% higher GHG emissions than the optimum, which has frequent production rate changes. When the standalone system and integrated system have the same annual total cost, the integrated system reduces GHG emissions by at least 18.8% and reduces electricity purchases by 66%. Therefore, the integrated operation can reduce GHG emissions of the system, where the maximum reduction is achieved by optimizing the design and operation of energy system equipment, considering the temperature of heating demands, and optimizing production rates of plants with constraints applied to changes of the rates.

Data Center Aggregators’ Optimal Bidding and Benefit Allocation Strategy Considering the Spatiotemporal Transfer Characteristics

The aggregator, an emerging entity in the electricity market, gathers and creates market power for the small flexible resources, which traditionally contain distributed generation, electric storage, and flexible load. Recently, the exploding growth of information technology demand gives rise to the data centers, whose participation in demand response (DR) is becoming increasingly significant for its remarkable performance in spatiotemporal transfer characteristics compared to conventional facilities. The high-quality DR potential of data centers provides a new opportunity for the profit-seeking data center aggregators (DCAs) to optimize their bidding plans in the day-ahead electricity market. Therefore, this article targets the formulation of the optimal bidding strategy of demand response aggregators (DRAs) to achieve the maximization of the joint benefit of both DCA and data centers. A spatiotemporal transfer characteristics-based optimization strategy is formulated to obtain the electricity purchasing scheme and arrangement of data centers. Meanwhile, the Shapley value method is introduced to design the appropriate and equitable DR reward mechanism that each DCA should compensate its customers, which would serve as a guarantee to ensure data centers' active participation in DR events and lay a solid foundation for the implementation of the DCA's optimal bidding strategy. Numerical tested results demonstrate the effectiveness of the proposed optimal bidding model and the benefit allocation mechanism, which profit both DRA and data centers when participating in DR programs while preserving their daily power demand.

Energy Storage Configuration of An Integrated Energy System Considering the Response of Air-Conditioning Load and The Uncertainty of Source-Load

The integrated energy system is developing rapidly because of its good energy efficiency. With the development of the integrated energy system, how to reduce the operating cost of the system and improve the utilization rate of new energy in the system has become the focus of today. This paper considers the response of air-conditioning load, and establishes a two-stage robust configuration model to integrate the energy storage of the energy system. The model aims at the lowest comprehensive annual cost, which includes the investment cost of energy storage, the compensation cost after the air-conditioning load response, the maintenance cost of the equipment, the cost of electricity purchase, the cost of natural gas, and the income from electricity sales. The results of the calculation example show that, compared with the case where the response of the air conditioning load is not considered and the energy storage is not configured, the energy storage configuration in the integrated energy system that considers the response of the air conditioning load can effectively cope with the uncertainty of the source load and improve the consumption rate of renewable energy.

Contract and Lyapunov Optimization-Based Load Scheduling and Energy Management for UAV Charging Stations

Nowadays, a large number of civilian unmanned aerial vehicles (UAVs) are increasingly being used in many of our daily applications. However, there are many kinds of UAVs that need to enhance their endurance due to their limited resources. In order to make the UAVs operate efficiently, it is necessary to schedule UAVs with charging requirements. In this paper, renewable energy production and storage equipment on the basis of traditional charging stations is adopted to reduce the power purchase from the distribution network as much as possible. An online algorithm based on Lyapunov optimization is proposed to schedule the charging of UAVs and the energy management of the charging station. Meanwhile, contract theory is used to design the optimal charging strategy in the case of information asymmetry. Hence, local renewable energy can be utilized to the greatest extent, and electricity purchase costs can be reduced. Through the incentive system, users can spontaneously charge at low peak times and avoid the risk of grid overload and high energy cost. The simulation results show that the algorithm can improve the efficiency of charging station operators, allowing users to avoid charging at peak times, and only use real-time information to schedule UAVs. Compared to other algorithms, the proposed scheme can bring good revenue to operators while ensuring long-lasting operations of charging stations.

A Hierarchical Control Approach for Power Loss Minimization and Optimal Power Flow within a Meshed DC Microgrid

This work considers the DC part of a hybrid AC/DC microgrid with a meshed topology. We address cost minimization, battery scheduling and the power loss minimization within the power distribution network through constrained optimization. The novelty comes from applying differential flatness properties to the microgrid components and formulating the cost and constraints in terms of the associated B-splines parametrization of the flat outputs (the voltages and currents of the system). This allows us to obtain optimal power profiles to minimize the power dissipation and the cost of the electricity purchase from the external grid. These profiles are tracked by a model predictive controller at the higher level, while at a a lower level a controller deals with the operation of the switches within the DC/DC converters. Extensive simulations under nominal and fault-affected scenarios using realistic data validate the proposed approach.