Renewable Portfolio Research Articles

Optimization of Renewable Energy Company Stock Portfolio for Investment Decision Making using the Markowitz Model

This study focuses on optimizing the renewable energy company's stock portfolio using the Markowitz model, which aims to balance risk and return for proper investment decision making. With the increasing demand for clean energy, portfolio optimization in the renewable energy sector is important for investors. This research takes into account historical stock performance and applies the Mean-Variance Optimization framework to minimize risk while maximizing return. This portfolio consists of selected renewable energy companies, and the analysis runs from September 2021 to August 2024. This study aims to analyze the allocation of investment portfolios in renewable energy company stocks in Indonesia. Based on the analysis results, the investment portfolio is allocated to five main stocks, namely BUMI.JK with an investment value of IDR 17,075,844 (17.08%), INDY.JK of IDR 5,825,852 (5.83%), KEEN.JK of IDR 33,766,798 (33.77%), RAJA.JK of IDR 43,084,876 (43.08%), and WIKA.JK of IDR 246,630 (0.25%). These results indicate that most of the funds are invested in RAJA.JK and KEEN.JK stocks, which contribute more than 75% of the total investment portfolio

Estimation of the Put Option Value for Solar Power Plant Operators Participating in the Renewable Portfolio Standard (RPS) Spot Market

Estimation of the Put Option Value for Solar Power Plant Operators Participating in the Renewable Portfolio Standard (RPS) Spot Market

Evaluating the effectiveness of climate change policies and initiatives in the United States: A comprehensive review

Climate change presents profound challenges, demanding effective policies to mitigate its impacts. This paper reviews the effectiveness of climate policies in the United States, analyzing scholarly articles, government reports, and relevant literature. The review covers diverse policies such as greenhouse gas regulations, renewable energy initiatives, energy efficiency programs, and adaptation measures. It assesses their success in reducing carbon emissions, advancing a low-carbon economy, and enhancing resilience to climate impacts. Key findings highlight significant successes, such as the rise in renewable energy due to renewable portfolio standards and reduced emissions from vehicle fuel efficiency standards. State-level initiatives, like carbon pricing and renewable energy targets, also show promising outcomes. However, the review identifies substantial challenges, including political and economic obstacles, inconsistent policies across states, and the need for better federal-state-local collaboration. Additionally, disparities in policy benefits, with marginalized communities facing greater burdens and limited access to renewable resources, are significant concerns. To enhance the effectiveness of climate policies, the study recommends fostering coherent policies across all government levels, promoting equitable and inclusive climate solutions, raising public awareness, and supporting innovation in clean technologies. This comprehensive review provides valuable insights for policymakers and stakeholders to develop strategies that effectively address climate change, promote sustainability, and ensure a fair transition to a low-carbon future.

Cooperation and Profit Allocation Mechanism of Traditional and New Energy Complementary Power Generation: A Framework for Renewable Portfolio Standards

To boost the sustainable development of energy and the environment, a new power system with clean energy sources has been proposed by the Chinese government and traditional coal-fired power units are being transformed into regulation service providers for this new energy power system. Then, in this study, complementary power generation cooperation between traditional coal-fired power and new energy power producers is analyzed and discussed, and the energy quota agents, power sellers, are also included. Based on the cooperation game idea, different decision-making models of the tripartite power entities are elaborately constructed. Then, according to the price linkage mechanism between new energy and traditional thermal power, the profit of all power subjects is calculated and the profit allocation process is also analyzed. The conclusions show that the similarity of the two wholesale power price coefficients verifies the symmetry of the cooperative status of power producers. For BPC and SPC quota patterns, for example, BPC is bundled with new energy power and green certificates, whereas SPC is separate. Under the SPC pattern, there is a critical value for effective cooperation between the two power producers in the price range of traditional thermal power or new energy, which can achieve a win–win situation of increasing economic benefits and the consumption scale. Under the BPC pattern, the dynamic benefit compensation mechanism, which is the corrected Shapley value based on the RPS quota ratio, can solve the compressed profit of traditional coal-fired power producers. In contrast, the overall effect of profit allocation using the nucleolar method is not ideal. This study aims to give full play to the elastic induction effect of RPS to promote the sustainable transformation of traditional thermal power energy, especially combining the market mechanism to encourage traditional coal-fired power units to improve green technology to advance the construction of the green power market in China.

Optimization strategies for green power and certificate trading in China considering seasonality: An evolutionary game-based system dynamics

China has adopted renewable portfolio standards and tradable green certificates (including hydropower) to increase the proportion of green power used and reduce carbon emissions. However, hydropower generation is affected by seasonal factors, making it difficult to increase green power consumption in water-scarce areas. Trading electricity and green certificates in regions with different resource endowments can effectively solve this problem. Therefore, this study uses evolutionary game theory to explore the impact of the change in the policy of issuing green certificates for hydropower on the strategic choices of the trading parties. Based on the evolutionary game model, a system dynamics model is established to explore the optimization strategies of green power and certificate trading under the influence of seasonal factors. The results of the case study show that (1) the price of green certificates varies with seasonal changes. (2) Sellers with abundant hydropower resources should increase the amount of hydropower connected to the grid during the water-abundant period to help deficit areas achieve their consumption targets (3) Expanding the scope of green certificates can gradually eliminate government subsidies and incentives and reduce the government's financial pressure.

Future role of ocean thermal energy converters in a 100% renewable energy system on the case of the Maldives

Energy transition on small islands is limited by the scarce availability of land, restricting large-scale implementation of onshore renewable energy technologies such as solar photovoltaics and wind power. Ocean energy technologies provide novel opportunities for land-constrained islands to achieve 100% renewable energy systems. While wave power is increasingly implemented in energy system modelling research, ocean thermal energy converters are not yet a standard technology in renewable energy technology portfolios. This research aims to study the impacts of ocean thermal energy converters on the energy system of the Maldives through a structured sensitivity analysis for the two scenario clusters covering e-fuel import and domestic production. The ocean thermal energy conversion plants are modelled using spatially and temporally resolved resource data and cost assumptions from a global upscaling scenario, considering the technology’s current development stage. Results show that ocean thermal energy converters play a limited role in 'purely' cost-optimised sub-scenarios due to the availability of very low-cost offshore floating photovoltaics, making it difficult for them to compete. Nevertheless, reduced requirement of energy storage technologies due to the stable electricity production of ocean thermal energy converters offers an option to diversify the renewable energy technology portfolio with only a minor increase in cost.

Electricity system optimisation based on python model for renewable electricity generation portfolio

100% renewable electricity scenarios have received great attention from industry and policy makers, this is due to its widespread need for technical, economical, and renewable integration action plans. In this research, a python model named WIBSS, is developed and tested for adequacy using sensitivity analysis and then used to simulate the Irish electricity system.In this investigation, the optimal cost was identified with the installed capacities needed for the electricity system for high electricity demand scenario, and the generation portfolios for the electricity system in Ireland is proposed.The electricity system parameters are determined and the levelised cost of electricity is optimised and tabulated. In this investigation, the optimal solution is identified to decrease curtailment and minimize the total cost. Overlay graphs are plotted, and the optimal renewable sources combinations are presented.This research of determining generation portfolios toward 100% renewable electricity systems demonstrates simulations of two different pathways for 2030 scenarios to meet electricity demand in Republic of Ireland. The renewable energy target appeared in the government climate action plan and the authors renewable energy target determined based on the simulation of the python model, with more than doubled photovoltaic installation, a significant reduction in offshore wind, and a substantial integration of battery capacity, the authors renewable energy target performs better than renewable energy target, the levelised cost of electricity were 57.22 €/mWh and 51.11 €/mWh respectively. The least cost pathway is extended to balance between electricity generation and electricity demand in 2040 scenario, and keys target were proposed for generation portfolios.

Navigating the energy transition with the Carbon-Energy-Green-Electricity scheme: An industrial chain-based approach for China's carbon neutrality

In exploring the intricate dynamics of China's energy transition towards a national certificate trading market, this study harnesses a two-stage game model to unravel the nuanced decision-making within the intertwined carbon emissions trading, energy-consumption permit trading, and electricity markets. A novel industrial chain-based policy framework, i.e., the Carbon-Energy-Green-Electricity (CEGE) scheme, is introduced to address the complexity inherent in aligning these trading markets towards carbon neutrality goals. Findings reveal that the current isolated energy transition policies lead to increased electricity prices and imposes redundant regulatory burdens on power companies. By advocating for the CEGE scheme, the study presents a strategic approach to alleviate these challenges, highlighting its potential to lower electricity costs and foster more efficient carbon reduction efforts. Furthermore, it underscores the importance of integrating energy transition policies, including CET, ECPTS, the renewable portfolio standards (RPS), and the tradable green certificate program (TGC), to enhance renewable energy adoption, offering a path to relieve financial pressures on households while supporting broader environmental and economic welfare improvements.

Impact analysis of the four-party evolutionary game in renewable portfolio standard under dynamic parameters

Renewable portfolio standard has become the primary policy tool to improve the integration of renewable energy. The motivation of the parties involved and the formulation of the policy parameters are crucial for the rapid development of renewable energy industry. However, the role of large consumers has often been neglected as the main party for renewable energy consumption, and the policy parameters have been dominated by static parameters. This paper innovatively introduces large consumers into the evolutionary game, constructs a four-party revenue matrix and the replicated dynamic equations, analyzes the equilibrium conditions of the evolutionary game, and constructs the functions of the key dynamic parameters over time, then simulates the behavioral strategies of the game players under the dynamic parameters with a system dynamics model. The optimal strategy is regulators waive regulation, while power plants, large consumers and power sales companies fulfill their quotas. Dynamic fines, dynamic quotas, and dynamic consumption prices have a large impact on each player, while dynamic TGC prices have a limited impact on them. Reasonably high fines in the initial stage are effective in facilitating each player to its stable state more quickly than static fines. Even if the fine is reduced in the later stages, it will not affect their strategies. High quotas and low consumption prices will significantly accelerate the exit of regulators from regulation, while power sales companies and large consumers will quickly fulfill their quota tasks. Only power generators prefer low quotas and high consumption prices. These results provide some recommendations for the setting of policy parameters.

Energy transitions of declining energy industries: the effect of renewable portfolio standards on the U.S. coal industry

Abstract This study examines the influence of Renewable Portfolio Standards (RPS) on coal industry employment and wages in the top 10 U.S. coal-producing states from 2001 to 2018, with a specific focus on the 2003-2009 RPS adoption period. Employing a difference-in-differences methodology and utilizing data encompassing employment, gas prices, and RPS-related MWh at the quarterly level, our findings reveal that RPS had only temporary and minor adverse effects on coal employment. These effects manifested with a delay of up to four quarters but dissipated within two years. Moreover, RPS had no significant impact on state’s coal sector wages.

An inter-provincial coordinate model under Renewable Portfolio Standards policy based on tradable green certificate options trading

The current territorial management model under Renewable Portfolio Standards in China cannot fully develop renewable energy due to the mismatch between high energy-consumption regions and renewable energy-rich regions. Therefore, we proposed an inter-provincial coordinate model based on tradable green certificate options trading (CMTOT), which includes four components: (1) A dual-objective optimization model is established to minimize the RPS target realization cost and maximize the pollutant emission reduction based on Blacke-Scholes option pricing model. (2) The identification of buyer and seller provinces of tradable green certificate (TGC) options based on the above model. (3) An optimization model in buyers' or sellers' cooperation alliance is established. (4) The cost allocation models by Shapley value and Nucleolus are established to ensure the fairness in different scenarios. A case study of Tianjin, Shandong, Shanxi and Inner Mongolia shows that the CMTOT can effectively reduce the RPS target realization cost by 16.79 % and increase the pollutant emission reduction by 4.32 %. A sensitivity analysis confirms the robustness of the CMTOT. The results show that the CMTOT can both fully develop renewable energy and effectively reduce pollutant emission. Therefore, we proposed some policy recommendations to support the implementation of the CMTOT.

Enhancing performance of shipboard photovoltaic grid-connected inverter through CRNN-LM-BP control optimized by particle swarm optimization of LCL parameters

The global renewable energy portfolio is experiencing a growing proportion of shipboard photovoltaic (PV) energy. Grid-connected system has become the development trend of photovoltaic power generation technology in marine applications because of its high energy utilization efficiency. However, in the grid-connected process, harmonic pollution is easily caused by time-varying marine environment disturbance, which affects the quality of grid-connected power. The current recurrent neural network Levenberg-Marquardt backpropagation (CRNN-LM-BP) method, a control methodology, is introduced in this paper to ensure the robustness, stability, and consistency of the system. In addition, the inductance-capacitance-inductance (LCL) filter is optimized using particle swarm optimization (PSO) to minimize the presence of high frequency harmonics. The system that has been developed possesses the ability to improve the accuracy of steady-state control, operate with high efficiency and effectiveness, and maintain a total harmonic distortion of 1.73 %. Concurrently, streamlining the Jacobian matrix in the LM algorithm expedites convergence. It enables the system to improve its dynamic response, minimize excess, and quickly return to a stable condition when faced with load variations, a wide range of filter parameter adjustments, and voltage fluctuations. The suggested method’s effectiveness and applicability are evaluated by comparing it to the traditional proportional-resonant control, CRNN-BP control, using Matlab/Simulink and the real-time simulator OPAL-RT5700..

Modeling multi-market coupling effects considering the consumption above quota trading market in renewable portfolio standards: An agent-based perspective

The current renewable portfolio standards (RPS) mechanism implemented in China requires electricity consumers to comply with quota obligations by consuming renewable electricity, purchasing tradeable green certificates (TGCs), or engaging in consumption above quota (CAQ) transactions. However, most existing studies on RPS policy seldom consider the CAQ market and ignore the dynamic interactions among microlevel obligated entities, which limits the model from considering the heterogeneity among obligated entities and weakens the capture of macrolevel emergence properties. To fill this research gap, a novel agent-based model for China's RPS policy is established, in which the microlevel obligated subjects' complex interactions and decision-making process in coordinating three compliance approaches, i.e., electricity consumption, TGC consumption and CAQ transactions, are depicted, and the dynamic macrolevel emergence in the electricity market, TGC market and CAQ market in terms of multimarket coupling trading, multimarket price-linkage, renewable energy electricity diffusion and RPS target compliance are captured. Notably, a genetic algorithm-based training stage is structured to calibrate and stabilize the heterogeneous behavioral parameters of obligated entities. The results illustrate that 1) the existence of the CAQ market in RPS policy can significantly stimulate obligated entities to consume more renewable energy electricity earlier, promote individual and aggregate profits, and improve the overall compliance rate and RPS implementation effectiveness and 2) a combined penalty–reward mechanism with an effective reward interval is highly important for promoting RE consumption diffusion and the effective operation of the CAQ market.

Maximizing Quantum Hole Collection on Anatase TiO2 Thin Films with (001) Facets for Photoelectrochemical Oxigen Evolution Reaction Efficiency

Hydrogen production from water, a key element in the renewable energy portfolio, offers a solution to reduce reliance on fossil fuels. Photoelectrochemical (PEC) hydrogen production, using light-absorbing semiconductors and catalysts, offers a clean and cost-effective method for harnessing solar energy. To enhance the efficiency of PEC, this study explores the use of anatase TiO2 thin film photoelectrodes as an alternative to expensive and rare catalysts, aiming to generate hydrogen as a clean fuel with oxygen as a byproduct.Anatase titanium dioxide is a well-established functional material widely applied in the fields of environment and energy. Recognized as one of the premier materials for photocatalysis and a promising photoanode material for water splitting, titanium dioxide (TiO2) finds use in diverse applications such as dye-sensitized solar cells, perovskite-based solar cells, and cleaning devices. Its band gap of 3.2 eV, stability, strong absorption in the UV region, and energetics of the valence and conduction band edges make anatase particularly suitable for PEC water splitting, especially for the oxygen evolution reaction (OER).Our research focuses on the development of anatase thin films with strong [001] texture and (001) facets at the surface of the film. The (001) facets are known to accumulate photogenerated hole states while the [001] orientation imparts a negative flat band potential. We hypothesize that these two properties, (001) facets and [001] texture, are ideal for OER. This study combines these two structural characteristics within the semiconductor TiO2 layer to enhance PEC performance and maximize the efficiency of hole collection during water oxidation.Anatase TiO2 thin films with (001) facets and [001] orientation were hydrothermally synthesized on a fluorine-doped tin oxide (FTO) substrate and annealed at 500°C. The films exhibited [001] orientation and (001) faceting as shown by grazing incidence X-ray diffraction (GI-XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Photoelectrochemical measurements via cyclic voltammetry in a 0.1 M KOH and Na2SO3 solution demonstrated the films' hole collection efficiency under a 365 nm UV light source. The photoelectrochemical (PEC) and oxygen evolution reaction (OER) characteristics of anatase thin films were observed both under dark and light conditions. Prior to illumination, only the Ti3+/Ti4+ redox couple was observed with an onset potential of 0.01 V (RHE) and negligible OER at anodic potentials. When UV irradiated, the TiO2 thin films exhibited a photocurrent that increased through the anodic scan. The onset potential of photocurrent, measured in the presence of the hole scavenger, exhibited a negative shift ranging from -100 to -200 mV compared to the KOH onset potential. This shift is attributed to the film surface's limited efficiency in collecting holes for water oxidation at low potentials, as rapid recombination kinetics compete with water oxidation. Interestingly, the photocurrent observed with Na2SO3 electrolyte was 0.15 to 0.3 times more than what we saw with KOH electrolyte. Our preliminary results indicate a current density of ~2.0-2.5 mA cm-2 at 1.8 V and a hole collection efficiency of ~84 % at 1.23 V vs RHE, the thermodynamic water oxidation potential. In summary, we have made significant progress toward enhancing the PEC activity of anatase TiO2 thin films by optimizing the film structure for both reactivity and charge transport.

Study of a Novel Updraft Tower Power Plant Combined with Wind and Solar Energy

This study presents a novel solar updraft tower power plant (SUTPP) system, which has been designed to achieve the simultaneous utilization of solar and wind energy resources in desert regions, in response to the pressing demand for sustainable and efficient renewable energy solutions. The aim of this research was to develop an integrated system that is capable of harnessing and converting these abundant energy sources into electrical power, thereby enhancing the renewable energy portfolio in arid environments. The methodology of this study involved the design and construction of a prototype SUTPP, comprising a 53 m high tower, a 6170 m2 collector, five horizontal-axis wind turbines, and a thermal energy storage layer made up of pebbles and sand. The experimental setup was meticulously detailed, and experiments were conducted to collect data on the system’s performance under various environmental conditions. Subsequently, three-dimensional numerical simulations were performed to explore the effects of ambient wind speed and solar radiation on the output power of the SUTPP. The results indicate that the output power of the system increases with the increase in ambient wind speed and solar radiation. The impact of solar irradiation on output power was observed to diminish as ambient wind speeds increased. Notably, as the inlet wind speed rose from 4 m/s to 12 m/s, the output power showed a substantial increase of 727%. The numerical simulations revealed that ambient wind speed has a more pronounced effect on power output compared to solar radiation. Furthermore, it was found that the influence of solar radiation is significant at low wind speeds, with its impact decreasing as wind speed increases. This research provides essential guidance for the design and engineering of highly efficient solar thermal energy utilization projects, representing a significant advancement in the field of renewable energy technology deployment in desert environments.

Comparing feed-in tariff and renewable portfolio standard in South Korea: Cost reduction impact on non-photovoltaic renewable electricity

Renewable energy (RE) electricity plays a crucial role in addressing climate change but has limitations, such as intermittent production, high costs, and site constraints. South Korea transitioned its RE support system from a feed-in tariff (FIT) to a renewable portfolio standard (RPS) in 2012. This study evaluates the impact of the FIT-to-RPS transition on cost reduction for non-photovoltaic RE technologies (RETs), i.e., onshore wind power, bioenergy power, small hydropower, and fuel cell power, using a learning curve model. The results indicate that the FIT-to-RPS transition did not have a significant positive impact on cost reduction for onshore wind power, bioenergy power, or small hydropower, as the results show negative learning rates (LRs) during both FIT and RPS periods. The analysis suggests that the positive learning effect was hindered by the gradual depletion of sites favourable to RE power plants as more RE power plants were installed. However, fuel cell power, which is not affected by land availability, increased the LR from 1.4 % to 3.5 %.This study has policy implications, such as improving excessive regulations and procedures that hinder the installation of RE power plants on sites with good condition.

Renewable energy policy performance and technological innovation in Africa: A Bayesian estimation

This paper examines the effect of renewable energy policy performance on innovation activity in the renewable energy sector in a sample of thirty-three African countries during the period 2010–2021. The policy performance we use covers carbon pricing, incentives for grid-connected and distributed renewable energy generation, fiscal incentives for renewable energy, legal framework for renewable energy, off-take risk, network connection and pricing, and policy design attributes. Using patent data and renewable policy performance to fit a Bayesian negative binomial, our results generally show that renewable energy policy in the region supports technological innovation in the sector. Policy initiatives focused on market-based incentives (auctions and tariffs), renewable portfolio standards, risk mitigation, network connection and pricing are largely responsible for a strong and statistically significant relationship between renewable energy policy and innovation activity. We also find evidence that intellectual property rights, renewable energy capacity, electricity prices, affordability of renewable energy, and openness to trade proxies are important drivers of innovation activity in the renewable energy sector. Our analysis finds no evidence that research and development is a significant determinant of renewable energy innovation in African countries. Our results serve to inform policymakers on the areas in which specific policy actions are most effective at promoting innovation in the renewable energy sector.

Rebuilding Ukraine’s energy supply in a secure, economic, and decarbonised way

Abstract Since Russia’s 2022 invasion, Ukraine’s civilian energy infrastructure has faced systematic attack and requires urgent and strategic reconstruction. This study confronts the dual challenges of rebuilding Ukraine’s energy system rapidly to mitigate civilian and economic disruption while aligning this to long-term goals of sustainability and energy security. We demonstrate that Ukraine can readily meet future energy demands through a fully renewable electrified system at costs comparable to those from fossil fuels and nuclear power. Contrary to previous re- liance on high-carbon energy sources, we find a diversified renewable energy portfolio, including significant solar photovoltaic and wind contributions, can ef- ficiently meet growing energy demands and position Ukraine as an energy ex- porter, leveraging its geographical advantages. The approach of our study, based on open data and models, extends beyond national borders and offers a model for post-conflict reconstruction that harmonizes immediate recovery with sustain- able energy transition.

A review of concentrated solar power status and challenges in India

Concentrated Solar Power (CSP) technology has emerged as a promising renewable energy solution, offering a sustainable and efficient means of electricity generation and thermal energy storage. India, endowed with abundant solar irradiance, has made significant strides in promoting CSP technology as part of its renewable energy portfolio. With a growing focus on reducing greenhouse gas emissions and enhancing energy security, the Indian government has initiated numerous policies, incentives, and projects to encourage CSP adoption. Parabolic trough collectors, a type of linear concentrating system, are currently in widespread use. Power or solar towers are the most common type of point concentrating CSP technology currently in use. India aims to achieve a renewable energy capacity of 175 GW by 2022, with solar power constituting 100 GW of the overall target. Concentrated solar power technology is slated to grow 87% during 2018–2023, 32% faster than in the previous five-year period 2012–2017 and reach 4.3 GW in 2023. In future, present review paper can be regarded as a valuable resource for researchers, policymakers and industry professionals seeking to comprehend the present condition of concentrated solar power in India. It can aid in the development of strategies to address obstacles and advance sustainable and efficient solar energy solutions.

Advancing Sustainable Power: A Comprehensive Review of Technologies and Strategies for Green Electricity Production.

The transition to sustainable energy systems is essential to address global environmental challenges, with green electricity production playing a crucial role. This comprehensive review examines the advancements in green electricity production technologies, focusing on solar, wind, biomass, and hydroelectric power. By exploring the efficiency, cost trends, adoption rates, and environmental impacts of these technologies, the review highlights their potential to transform the energy landscape. Solar PV and wind energy have seen substantial improvements in efficiency and cost reduction, while biomass and hydroelectric power offer valuable contributions to a diversified renewable energy portfolio. Despite the challenges, ongoing research and innovation are driving the adoption and integration of these technologies, paving the way for a sustainable and resilient energy future. The findings underscore the importance of leveraging a multifaceted approach to green electricity production, emphasizing the need for continued advancements and strategic integration of renewable energy sources.