Renewable Portfolio Research Articles

Behaviours of Multi-Stakeholders under China’s Renewable Portfolio Standards: A Game Theory-Based Analysis

China has implemented both quantitative and policy incentives for renewable energy development since 2019 and is currently in the policy transition stage. The implementation of renewable portfolio standards (RPSs) is difficult due to the interests of multiple stakeholders, including power generation enterprises, power grid companies, power users, local governments, and the central government. Based on China’s RPS policy and power system reform documents, this research sorted out the core game decision problems of China’s renewable energy industry and established a conceptual game decision model of the renewable energy industry from the perspective of local governments, power generation enterprises and power grid companies. The results reveal that for local governments, the probability of meeting the earnings quota or punishments for not reaching quota completion are the major determinants for active participation in quota supervision. For power grid firms, the willingness to accept renewable electricity quotas depends on the additional cost of receiving renewable electricity and governmental incentives. It is reasonable, from the theoretical perspective, to implement the RPS policy on the power generation side. Electricity reform will help clarify the electricity price system and increase the transparency of the quota implementation process. Policy implications are suggested to achieve sustainable development of the renewable energy industry from price incentives and quantity delivery.

Goal programming models with interval coefficients for the sustainable selection of marine renewable energy projects in the UK

In this paper, a strategic decision making model for the sustainable development of marine renewable energy is proposed, and a specific application to the United Kingdom (UK) is demonstrated. As an island nation the UK benefits from significant marine energy potential which is providing an increasing contribution to UK's renewable energy portfolio. The paper investigates the question of how decision makers can be aided to reach a decision on which types of marine renewable energy projects should be chosen for development given that strategic energy planning is subject to a number of uncertain parameters and multiple sustainability objectives. In this context, the contribution of this paper lies in the combination of renewable energy portfolio selection and the application of multi-objective methods. Interval coefficient goal programming models are adopted in order to address the impreciseness and uncertainty associated with the goals and coefficients of the models in the context of renewable energy selection. The potential renewable energy projects are clustered in order to aid the decision making process and preferential weight sensitivity methods are employed. Conclusions are drawn for optimistic and pessimistic scenarios in the context of UK marine renewable energy planning.

The Value of Inter-Regional Coordination and Transmission in Decarbonizing the US Electricity System

Summary Preventing global warming in excess of 1.5°C–2°C requires a transition to zero-carbon electricity systems by midcentury along with the widespread electrification of other sectors. Current state-level renewable portfolio standards and regional transmission arrangements do not capture the benefits of inter-regional transmission or coordination of planning and dispatch for renewable-energy integration. Here, using a co-optimized capacity-planning and dispatch model over 7 years of hourly operation, we show that inter-state coordination and transmission expansion reduce the system cost of electricity in a 100%-renewable US power system by 46% compared with a state-by-state approach, from 135 $/MWh to 73 $/MWh. Sensitivity analyses show that reductions in the cost of photovoltaics, wind, and lithium-ion batteries lead to the lowest electricity costs for systems in which transmission expansion is allowed, while cost reductions for nuclear power or long-duration energy storage lead to greater electricity cost reductions for isolated systems.

A Study on the Performance and Policy Evaluation of Turbo Expander Generation Interconnected to Distribution Systems

In the face of environmental problems, the energy industry needs to convert energy sources into clean energy, but the technological maturity of renewable energy such as solar and wind power is not high enough, so each country is implementing expansion and dissemination policies based on various systems. The most representative energy policy, renewable energy certificate (REC) transaction system, based on the renewable portfolio standard (RPS), is a policy to supplement the economic feasibility of renewable generations until the technological maturity of them is completed, and is characterized by giving proper weights to each sources. TEG, a power generation source that utilizes waste pressure in the process of decompressing high-pressure gas, is one of the new renewable power candidates in the spotlight in terms of high eco-friendliness and energy recovery. In this paper, the economic and policy factors are evaluated to calculate the REC multipliers for new types of power sources. In particular, it is estimated based on the power generation and electricity sales performance data collected through the operation of the 300 kW TEG operating at the Gimhae decompression facility in Korea.

Hierarchical, Grid-Aware, and Economically Optimal Coordination of Distributed Energy Resources in Realistic Distribution Systems.

Renewable portfolio standards are targeting high levels of variable solar photovoltaics (PV) in electric distribution systems, which makes reliability more challenging to maintain for distribution system operators (DSOs). Distributed energy resources (DERs), including smart, connected appliances and PV inverters, represent responsive grid resources that can provide flexibility to support the DSO in actively managing their networks to facilitate reliability under extreme levels of solar PV. This flexibility can also be used to optimize system operations with respect to economic signals from wholesale energy and ancillary service markets. Here, we present a novel hierarchical scheme that actively controls behind-the-meter DERs to reliably manage each unbalanced distribution feeder and exploits the available flexibility to ensure reliable operation and economically optimizes the entire distribution network. Each layer of the scheme employs advanced optimization methods at different timescales to ensure that the system operates within both grid and device limits. The hierarchy is validated in a large-scale realistic simulation based on data from the industry. Simulation results show that coordination of flexibility improves both system reliability and economics, and enables greater penetration of solar PV. Discussion is also provided on the practical viability of the required communications and controls to implement the presented scheme within a large DSO.

Application of agent-based modeling and life cycle sustainability assessment to evaluate biorefinery placement

Biofuels, such as those derived from woody biomass, are being developed as one part of a renewable energy portfolio; however, it remains unclear if they can be sustainably developed. This manuscript demonstrates that the use of agent-based modeling (ABM) and life cycle sustainability assessment (LCSA) as part of an integrated methodology allows for robust assessment of the possible impacts. A case study of a proposed biorefinery in Ontonagon, Michigan, USA is conducted. In the case study, ABM is used to project the harvest decision making of forest owners and loggers to determine if they were willing to harvest and supply woody biomass to the biorefinery under several different price points. The results from the ABM were used to inform inventory data for projections of environmental impacts, along with projected impacts for economic and social concerns. The results of the case study show that while Ontonagon is a promising site for a biorefinery, the quantity of woody biomass delivered is a concern along with potential impacts to wetlands in the region. Ultimately, this case study suggestions that the integration of ABM and LCSA may be effective the assessment of other biorefineries.

Coordination of tradable carbon emission permits market and renewable electricity certificates market in China

Abstract In order to assist the low-carbon transformation of power sector, China is planning to establish the national Tradable carbon emission permits (TEPs) market and Renewable Electricity Certificates (RECs) market under mandatory carbon caps and Renewable Portfolio Standards (RPS) targets simultaneously. How to coordinate the two markets and what the coordination effects are become key issues. In the present study, a multi-region multi-market equilibrium model considering both mechanisms was developed and applied to China as the case study. The model established the effective coordination interval between RPS targets and carbon caps in which the two markets can operate jointly. Then the coordinated markets were proved to be more economically efficient so long as the government pursues the dual goal of reducing carbon emission and promoting renewable energy in sync. Finally, the theoretical and practical advantages of market coordination compared with uncoupled operation of these markets, such as diversifying markets risk, keeping TEP/REC price at lower level, and reducing consumers' electricity purchase cost, were discussed.

Computing a Strategic Decarbonization Pathway: A Chance-Constrained Equilibrium Problem

US transmission systems and wholesale electricity markets, albeit federally regulated, often span across multiple state jurisdictions. In this environment, state regulators can strategically exploit this techno-economic coupling to advance their clean energy policy goals at the expense of neighboring jurisdictions. This paper investigates strategic regulatory competition to understand its effect on achieving Renewable Portfolio Standards (RPS). We formulate a chance-constrained equilibrium problem with equilibrium constraints (CC-EPEC), which considers multiple state regulators, acting in coordination with in-state power companies, to implement RPS goals in the least-cost manner. To solve this CC-EPEC, we customize a Progressive Hedging (PH) algorithm. The case study uses the CC-EPEC and PH algorithm to analyze the effects of state regulatory competition in the ISO New England system.

Guidance to Reduce the Cardiovascular Burden of Ambient Air Pollutants: A Policy Statement From the American Heart Association.

In 2010, the American Heart Association published a statement concluding that the existing scientific evidence was consistent with a causal relationship between exposure to fine particulate matter and cardiovascular morbidity and mortality, and that fine particulate matter exposure is a modifiable cardiovascular risk factor. Since the publication of that statement, evidence linking air pollution exposure to cardiovascular health has continued to accumulate and the biological processes underlying these effects have become better understood. This increasingly persuasive evidence necessitates policies to reduce harmful exposures and the need to act even as the scientific evidence base continues to evolve. Policy options to mitigate the adverse health impacts of air pollutants must include the reduction of emissions through action on air quality, vehicle emissions, and renewable portfolio standards, taking into account racial, ethnic, and economic inequality in air pollutant exposure. Policy interventions to improve air quality can also be in alignment with policies that benefit community and transportation infrastructure, sustainable food systems, reduction in climate forcing agents, and reduction in wildfires. The health care sector has a leadership role in adopting policies to contribute to improved environmental air quality as well. There is also potentially significant private sector leadership and industry innovation occurring in the absence of and in addition to public policy action, demonstrating the important role of public-private partnerships. In addition to supporting education and research in this area, the American Heart Association has an important leadership role to encourage and support public policies, private sector innovation, and public-private partnerships to reduce the adverse impact of air pollution on current and future cardiovascular health in the United States.

Features extraction of wind ramp events from a virtual wind park

In the European renewable energy portfolio, wind has a sizeable share in the total energy production. The Nordic and Baltic energy systems in particular are benefiting from wind energy to reach the greenhouse gas emissions reduction objectives set by the EU. The wind energy production varies with time, and this intermittent characteristic imposes a challenge for full utilization of renewable energy potential. The power system operator needs to ensure timely power supply of demand. An accurate estimation of power output from a non-dispatchable generation resource such as a wind farm is essential for the operator to ensure the supply–demand balance and adequate sizing of reserve power capacity. Existing methods of feature extraction and prediction such as linear regression often overlook the significant variations or do not utilize in the model building. However, this method misinterprets the trend in data. Understanding the properties of the variations in more details would reduce the uncertainty and significantly improve the feature extraction to aid in decision making. Furthermore, as the volume, shape and type of dataset start to increase and new methods are required to extract meaningful information from the patterns in the big data. The objective of the paper is to present a novel Ramping BehaviourAnalysis (RBAθ) model that identifies and quantifies the variations in a time-varying dataset. The variations are classified into significant and stationary events. The former refers to the significant swings beyond a set threshold range and the latter refers to the swings that are relatively within the threshold limits. The features associated to each event include start time, end time, change in magnitude, persistence of an event, angle at which the event took place and frequency of occurrences of the features. In addition, the rain-flow cycles count is extracted from the original data for each event as a sum of half cycles and full cycles. The model is validated using simulated wind power production data from a virtual wind park spread across Estonia and the results are elaborated. The spatial dynamics of the virtual windfarm are captured through localized spatial autocorrelation of the events with the geospatial locations of the turbines. The results demonstrate that RBAθ precisely and accurately identify and quantify the time varying power generation into events with subsequent features. The volume of the data is significantly reduced in the process of summarizing time series data into a series of events. Thereby RBAθ can be also used for data compression and reconstruction with minor losses. The system operators can use the proposed algorithm in operational scheduling, maintenance and investment-capacity building decisions.

Predictive-Maintenance Practices: For Operational Safety of Battery Energy Storage Systems

Changes in the Demand Profile and a growing role for renewable and distributed generation are leading to rapid evolution in the electric grid. These changes are beginning to considerably strain the transmission and distribution infrastructure. Utilities are increasingly recognizing that the integration of energy storage in the grid infrastructure will help manage intermittency and improve grid reliability. This recognition, coupled with the proliferation of state-level renewable portfolio standards and rapidly declining lithium-ion (Li-ion) battery costs, has led to a surge in the deployment of battery energy storage systems (BESSs). Although BESSs represented less than 1% of grid-scale energy storage in the United States in 2019, they are the preferred technology to meet growing demand because they are modular, scalable, and easy to deploy across diverse use cases and geographic locations.

Will China achieve its renewable portfolio standard targets? An analysis from the perspective of supply and demand

To promote renewable energy integration in China's power grids, the Chinese government has set forth renewable portfolio standards. This paper analyzes the feasibility of renewable portfolio standard from the perspectives of the supply and demand of renewable electricity. A multiple regression model is established to predict the demand of 30 provinces for renewable electricity in 2020 under various scenarios. The renewable power supply is measured based on the provincial plans for renewable electricity demand. The results suggest four main conclusions. (1) If all provinces can implement their respective renewable energy planning, the renewable power supply will exceed the renewable portfolio standard targets by about 488 TWh (including 155 TWh of non-hydro power). (2) Guangdong, Shanghai, Jiangsu, Zhejiang and Chongqing will experience the greatest lack of renewable electricity; the shortfall in these provinces will reach 320 TWh, representing 77% of the total renewable portfolio standard target. (3) The greatest shortfall of non-hydro power will occur in Beijing, Jiangsu, Tianjin and Zhejiang; this shortfall will be approximately 39 TWh, accounting for 69% of the total non-hydro power shortfall. Moreover, the non-hydro power supply will far exceed the policy targets in Xinjiang, Qinghai, Inner Mongolia and Gansu. (4) China's renewable portfolio standard policy will further promotes the optimal allocation of renewable energy resources among provinces via inter-provincial transactions.

North American natural gas market and infrastructure developments under different mechanisms of renewable policy coordination

Renewable Portfolio Standards (RPS) accelerate renewables deployment but their impact on fuel-fired plants remains ambiguous. North American natural gas consumption has been growing due to its decreasing cost in North America, policy initiatives, and its relatively low CO2 emissions rate compared to coal. In this paper, we study the implications for the natural gas sector of more stringent RPS under different coordination schemes in an integrated North American natural gas market. The scenarios assume that Renewable Energy Certificates generated in each region are traded 1) among all countries, 2) only within each country, and 3) only within model regions. We implement the three policies in four different energy and electricity models to generate projections of future natural gas consumption. Subsequently, we feed regional or country-level consumption changes of each model in each scenario to the North American Natural Gas Model. We find that lower RPS coordination among regions results in increased U.S. natural gas exports to Canada, increased U.S. natural gas prices, and decreased net U.S. natural gas exports to Mexico in the long term. Moreover, international coordination of RPS in the electricity sector leads to smaller price discrepancies in the U.S. natural gas market when compared to the reference scenario.

Joint Computation Offloading and Demand Response Management in Mobile Edge Network With Renewable Energy Sources

Mobile Edge Computing (MEC) networks have recently developed to integrate renewable sources for providing sustainable and low-cost computation/energy services. However, one challenging problem is how to guarantee the stable and effective services for numerous devices under highly intermittent renewable generations and variable computation/energy demands. In this paper, we consider to co-deploy the edge servers and energy storage at micro Base Station (BS) in each edge sub-network. In the considered scenario, we first determine the number of edge servers and energy storage units at different sub-edge networks in a long-term period. Then, we jointly design the offloading and demand response policies for all micro BSs in a centralized manner. Considering the variabilities of renewable energy and computation/energy demands, the system cost is minimized while meeting the energy demand-supply balance and renewable portfolio standards. Furthermore, a distributed optimization problem is formulated to find the optimal offloading parameters, the amount of charging/discharging energy and utilized renewable energy of the micro BS without handing over all operational information. Numerical results show that the proposed deployment and policies can provide effective offloading and energy saving strategies for the proposed mobile edge network.

A critical review of Korea's long-term contract for renewable energy auctions: The relationship between the import price of liquefied natural gas and system marginal price

The aim of Korea's Renewable Portfolio Standard (RPS) and newly adopted auction system with a long-term fixed-price renewable contract was to support renewable energy providers in hedging electricity and Renewable Energy Certificate (REC) price risks. This study found a long-run positive relationship between the import price of Liquefied Natural Gas (LNG) and System Marginal Price (SMP) in Korea, demonstrating that the fluctuations in global fuel prices are likely to increase uncertainties in renewable investments. The fixed-price contract, which cannot be revised once determined, encourages renewable energy providers' speculative decision-making, and the uncertainty caused by the contract system may discourage investment decision-making.

Electrocatalysts for direct methanol fuel cells to demonstrate China's renewable energy renewable portfolio standards within the framework of the 13th five-year plan

A unified treatment of the renewable portfolio standards is given concerning direct methanol fuel. The current mechanism of electrocatalysis of methanol oxidation on platinum and non-platinum-containing alloys is summarized for the systematic improvement of the rate of electro-oxidation of methanol are discussed. Policy realignment under the five-year plan is discussed in length to demonstrate how policy, markets, and engineering designs contribute towards the development of model direct methanol fuel cells operational enhancement, and factors that affect critical performance parameters for commercial exploitation are summarized for catalytic formulations and cell design within the context of why this investment in technology, education, and finances is required within the global context of sustainable energy and energy independence as exposed by thirteenth the five-year plan. The prolog focuses on the way, whereas the section on methanol fuel cells on the how and the post log on what is expected post-COVID-19 era in science and technology as China pivots to a post-fossil fuel economy.China's industrial growth has been through internal market reforms and supplies side economics from the Chinese markets for fossil fuels except for petroleum. The latest renewable portfolio standards adopted have common elements as adopted from North American and the United Kingdom in terms of adaptation of obligation in terms of renewable portfolio standards as well as a realization that the necessity for renewables standards for the thirteen five year plan (from 2016 to 2020) need to less rigorously implemented due to performance targets that were met during the eleventh (06–10) and twelfth five-year plans (11–15) in terms of utilization of small coal-ire power plants, development of newer standards, led to an improvement of energy efficiency of 15 %, reduction of SOx/NOx by an average of 90 % and PM2.5 by 96 % over the last two five-year plans.The current phase of the plan has a focus on energy generation from coal and a slowing down of renewables or Renewable energy curtailment of approximately 400 T Wh renewables including 300 T Wh of non-hydro power, principally from Guangdong, and Jiangsu for transfer of hydropower and Zhejiang, Tianjin, Henan for non-hydro power transfer with Beijing and Shanghai playing important roles in renewables energy curtailment and realignment using an integrated approach to optimize each provinces energy portfolio. The realignment of the renewable energy portfolio indicates that the newly installed capacity in Sichuan, Yunnan, Inner Mongolia, and Zhejiang will account for less than 20 % of the current renewable energy portfolio but with the NOx SOx and PM2.5 savings already accrued.The catalytic reduction of carbon dioxide to methanol (70 / 110 million metric tons from all sources in 2019 for China/world) is one technological approach to reduce global carbon dioxide emissions and suggests that catalytic methanol synthesis by CO2 hydrogenation may be a plausible approach, even if it is more expensive economically than methanol synthesis by the syngas approach. This is because the CO2 emissions of the synthesis are lower than other synthesis methodologies. The Chinese government has placed a premium on cleaner air and water and may view such an approach as solving the dual issues of fuel substitution and reduction of CO2. Thus, the coupling of hydrogen generation from sustainable energies sources (Solar 175 / 509 GW) or wind (211/591.5 GW in 2019) may be an attractive approach, as this requires slightly less water than coal gasification. Due to the thermodynamic requirement of lower operating pressure and higher operating pressure, currently, there is no single operational approach, although some practice approaches (220 °C at 48 atm using copper) and zinc oxide/alumina are suggested for optimal performance.

Renewable energy requirements on the ballot: An analysis of county-level voting results

National polling data consistently find a large, bipartisan group of Americans support state renewable portfolio standards (RPS), policies which mandate generation of electricity from renewable sources. However, when such policies are actually put before voters on the ballot, they have been met with mixed success: out of seven RPS ballot initiatives, only four have been approved. From a newly compiled dataset of county-level voting results, we use ordinary least-squares regression to investigate the determinants of public support for RPS ballot proposals. Two models are constructed based on literature related to legislative adoption of RPS and, separately, public support of pro-renewable policies. Consistent with previous studies, political, economic, and demographic variables are found to be significant in predicting voter behavior. State-level fixed effects, however, are the largest contributors to both models. A synthesis model, combining elements from both the legislative adoption and public acceptance literatures, performs best when fixed effects are removed. As climate advocates increasingly call for policies to more quickly transition the electricity sector to renewable energy sources, this research provides greater insight into the prospects of successfully achieving that aim through a ballot initiative. It also, however, reveals insights applicable to legislature-driven RPS policies.

Impact of market design on cost-effectiveness of renewable portfolio standards

A renewable portfolio standard (RPS) is a policy instrument designed to increase production of clean energy technologies by mandating a minimum market share for these technologies. However, the cost-effectiveness of RPS in achieving its goal depends on the market structure, which impacts the level of competition in the market. Here, we analyze the impact of market structure on RPS effectiveness by calculating the amount of subsidies needed to achieve RPS mandates. We identify a critical market share of renewable energy that can be achieved by providing an equal amount of subsidy in both regulated and deregulated markets. We find wide variation in the preferred market structure for state-level RPS policies across the United States. Overall, deregulated markets minimize subsidy requirements for clean energy technologies with lower penetration rates. In contrast, regulated markets minimize subsidy requirements for higher market share mandates. The critical market share can help policymakers design more cost-effective RPS mandates in both regulated and deregulated markets.

Impact of government regulation of RPS on China’s power market under carbon abatement constraints

In a significant period of Chinese energy reformation to the point of expediting revolution in energy production and consumption, and promoting green low-carbon upgrading transformation of energy electricity, Chinese government has to implement the obligatory policy of renewable portfolio standards (RPS) with specific institutional provisions sternly. The renewable energy quotas in thermal power industry with carbon emission abatement constraints particularly have a latent impact on the behavior of thermal electricity producers, which is ineluctably involved in electricity connection of grid companies. To make clear the positive role in boosting investment in renewable energy generation in thermal power industry under mandatory quotas requirements, we will utilize evolutionary game based on system dynamics (SD) to tackle with the sophisticated nexus among the government, thermal power producers and grid companies. We begin analysis of general evolutionary strategy stability in scenario ll by dynamically adjusting values of external variables of SD model to uncover pivotal variables affecting evolutionary strategy stability. Then in scenario I, the dynamic punishment structure consisting of cost elements to spark off the emulation of optimal manoeuvre selections of tripartite game agents is amended based on the simulation of vital variables affecting evolutionary strategy stability in scenario II. The significant conclusions provide decision-making support and management enlightenment for Chinese government to edge renewable energy generation capacity of thermal power producers and constrained degree of dynamic penalty for grid companies.

Robust optimisation framework for SCED problem in mixed AC‐HVDC power systems with wind uncertainty

Wind power uncertainties have made the large integration of wind power generating units in the power system highly challenging. One promising solution to overcome the challenges associated with the intermittency of the renewable energy resources (RESs) is to connect areas with diverse renewable energy portfolios via high voltage direct current (HVDC) transmission lines with controllable power transfer capability. The installation of HVDC transmission lines in the power system has resulted in the evolution of conventional alternating current (AC) networks to mixed AC-HVDC power systems. In this study, to address wind power uncertainties in mixed AC-HVDC multi-area power systems, a modified robust optimisation (RO) model for the security-constrained economic dispatch (SCED) problem is proposed. The proposed RO model is used to minimise the generation cost and wind power curtailment under the worst-case scenario of actual wind power. Unlike the existing RO models, the proposed RO model considers a modified uncertainty set based on the wind power admissibility and addresses the budget of uncertainty more accurately to adjust the solution's level of conservatism. Extensive numerical studies demonstrate the economic and operational advantages of the proposed RO model for solving the SCED problem in mixed AC-HVDC power systems with high penetration of RESs.