Specific Energy Sources Research Articles

DEVELOPMENT DIRECTIONS OF ENERGY SOURCES FOR UNMANNED AERIAL VEHICLE (UAV)

The aim of the research was to conduct a comprehensive analysis of various energy sources used in unmanned aerial vehicles (UAVs) and to determine which implemented energy sources are the best as well as what are the directions of energy source development. One hundred drone models were selected for the study, differing in their installed energy source, flight time, payload capacity, own weight, and application. The analyzed UAVs were powered by 6 energy sources: lithium polymer and lithium-ion batteries, combustion engines, hybrid drives, hydrogen fuel cells, and solar energy. The analysis covered both technical and economic, environmental, and operational aspects influencing the choice of a specific energy source. It allowed determining the best energy source for each of the 4 selected applications: military, monitoring, transport, and agriculture. An assessment of challenges related to the use and development of energy sources was also carried out, and areas where further research and innovation are necessary and essential were identified. It was found that in military applications, the development of UAV energy sources will focus on combustion engines and electric propulsion with lithium polymer batteries. In civilian applications (in transport, monitoring, and agriculture), it will be directed towards further research and improvement of hybrid drives and hydrogen fuel cells.

Defenders of the status quo: energy protests and policy (in)action in Sweden

Abstract Are the positions that protesters take—in favor or against change—consequential for their ability to affect policy? While previous research suggests that protests can inform legislative priorities and facilitate policy introduction, this paper emphasizes policy inaction and stasis as goals of some protest actions. Analysis uses novel and detailed data on energy-related protest and policy actions in Sweden covering a forty-year period and considers protest frequency and size in relation to proposal introduction. The research design uniquely distinguishes between protests in favor or against a specific energy source and proposal activity in line with those demands and also controls for public opinion on each energy source. Findings suggest that pro-renewable energy protests do not yield pro-renewable policies but prevent undesired policies that support non-renewable energy sources. In contrast to pro-renewable protests, protests against renewable energy sources are somewhat more influential. They likewise prevent the introduction of their undesired proposals and also influence the introduction of proposals supporting non-renewable energy sources. Overall, the paper examines policy inaction as a desired protest outcome and argues protest—as a tactic—may be more effective when pushing against rather than for policy change.

Enhancing Energy Harvesting Efficiency from Ambient Sources through Advanced Materials and Nanotechnology

The utilization of ambient energy sources for powering small-scale electronic devices and sensors has garnered significant attention due to its potential for sustainable and autonomous operation. This research focuses on enhancing the efficiency of energy harvesting from ambient sources, such as vibrations, heat differentials, and electromagnetic fields, through the integration of advanced materials and nanotechnology into energy harvesting systems. The study begins with a comprehensive review of existing energy harvesting technologies, highlighting their limitations in terms of efficiency, scalability, and adaptability to various ambient energy sources. It identifies the key challenges faced in achieving high energy conversion rates and explores the potential of advanced materials and nanoscale structures to address these challenges. One aspect of the research involves the development and characterization of novel materials with superior energy conversion properties. This includes the synthesis of piezoelectric materials for vibration energy harvesting, thermoelectric materials for heat-to-electricity conversion, and nanomaterials for enhancing electromagnetic energy harvesting efficiency. Advanced characterization techniques, such as scanning electron microscopy (SEM) and X-ray diffraction (XRD), are employed to analyze the structural and electrical properties of these materials. Furthermore, the study investigates the design and fabrication of nanostructured energy harvesting devices optimized for specific ambient energy sources. This involves the integration of nanoscale components, such as nanostructured electrodes, into energy harvesting systems to improve energy capture and conversion rates. Finite element analysis (FEA) simulations and experimental testing are conducted to evaluate the performance and efficiency of these nano-enhanced energy harvesting devices under real-world conditions. The research also addresses the optimization of energy harvesting system parameters, including resonance tuning, impedance matching, and energy management circuits, to maximize energy extraction and utilization. Computational modeling techniques, such as multiscale modeling and finite element simulations, are utilized to optimize system configurations and improve overall energy harvesting efficiency. Overall, this research contributes to the advancement of energy harvesting technologies by leveraging advanced materials and nanotechnology, paving the way for sustainable and autonomous power generation from ambient energy sources for a wide range of applications.

Reliable renewable energy forecasting for climate change mitigation

Accurate prediction of electricity generation from diverse renewable energy sources (RES) plays a pivotal role in optimizing power schedules within RES, contributing to the collective effort to combat climate change. While prior research often focused on individual energy sources in isolation, neglecting intricate interactions among multiple sources, this limitation frequently leads to inaccurate estimations of total power generation. In this study, we introduce a hybrid architecture designed to address these challenges, incorporating advanced artificial intelligence (AI) techniques. The hybrid model seamlessly integrates a gated recurrent unit (GRU) and a ResNext model, and it is tuned with the modified jaya algorithm (MJA) to capture localized correlations among different energy sources. Leveraging its nonlinear time-series properties, the model integrates meteorological conditions and specific energy source data. Additionally, principal component analysis (PCA) is employed to extract linear time-series data characteristics for each energy source. Application of the proposed AI-infused approach to a renewable energy system demonstrates its effectiveness and feasibility in the context of climate change mitigation. Results reveal the superior accuracy of the hybrid framework compared to more complex models such as decision trees and ResNet. Specifically, our proposed method achieved remarkable performance, boasting the lowest error rates with a normalized RMSE of 6.51 and a normalized MAPE of 4.34 for solar photovoltaic (PV), highlighting its exceptional precision in terms of mean absolute errors. A detailed sensitivity analysis is carried out to evaluate the influence of every element in the hybrid framework, emphasizing the importance of energy correlation patterns. Comparative assessments underscore the increased accuracy and stability of the suggested AI-infused framework when compared to other methods.

Comparative Analysis of Hybrid and Single‐Source Power Systems for Sustainable Electricity Generation for Remote Areas: A Case Study in Zahedan

Providing sustainable electricity access to remote areas is critical for economic development and environmental preservation. This study investigates the performance of single‐source and hybrid renewable energy systems for the town of Zahedan, Iran, which has significant solar and wind energy potential. Using TRNSYS software, eight configurations were simulated and analyzed, comprising two single‐source (photovoltaic [PV] and wind turbine [WT]) and six hybrid systems incorporating combinations of PV panels, WTs, alkaline fuel cells, and diesel generators. The analysis revealed that hybrid systems, particularly those combining PV and WT, outperformed single‐source configurations. For instance, a hybrid system with 800 kW of PV and a 50 kW WT reduced diesel consumption by 35% and CO2 emissions by 45% compared to a system relying solely on a diesel generator. Conversely, the configuration involving WTs, fuel cells, and diesel generators showed high energy dumping (1,821,776 kWh) and considerable diesel usage, underscoring the challenges of maintaining energy balance without solar integration. Overall, hybrid renewable systems generally provide enhanced reliability and environmental benefits, although their performance heavily depends on the specific energy source mix. This study offers insights into optimizing renewable energy systems for remote locations, highlighting the necessity of a balanced solar‐wind combination to achieve optimal sustainability and cost‐effectiveness. The findings are applicable to regions with similar climatic conditions and contribute to global sustainable energy solutions, providing crucial information for policymakers and investors focused on supporting sustainable energy projects in isolated areas.

Harvesting energy overview for sustainable wireless sensor networks

Energy harvesting (EH) has emerged as a transformative research paradigm by converting ambient energy into electrical energy for natural and artificial applications. This paper explores the potential of EH in powering autonomous electronic devices facilitated by simplified processes to harness kinetic, solar, thermal, wind, and salinity gradients. Mainly, the focus lies on the applicability of these energy sources to small wireless automatic devices used in wireless sensor networks (WSNs). WSNs consist of cutting-edge sensors spatially distributed to monitor physical conditions and organize collected data at a central network location. Their pervasive existence enables efficient computing through sound resource management, interconnected via the internet and other high-tech innovations. This study evaluates EH developments to minimize resource utilization in WSNs, examining key features, proposed frameworks, and models. Furthermore, it reviews specific energy source productions utilized by WSNs. The feasibility of energy storage is also discussed, highlighting its potential for WSNs and paving the way for future directions in this field.

Asymmetric effect of renewable and non-renewable energy consumptions on corporate cash holdings: new panel data evidence from BRICS economies

PurposeIn the recent wake of environmental sustainability, more attention has been paid to the consumption of specific energy types. However, how the consumption of such energy alternatives influences multiple corporate-level decisions has not yet been well explored in the literature. The current analysis bridges this deficiency in literature by exploring the empirical relationship between energy alternatives and cash holdings.Design/methodology/approachFor empirical analysis, the authors sample the non-financial sector enterprises founded in five BRICS economies and employ the system GMM and fully modified ordinary least square techniques to establish the regression. The selection of econometric techniques is subject to the existence of endogeneity and cointegration.FindingsThe estimated coefficients reveal a significant negative effect of renewable energy (REC) while a significant positive impact of non-renewable energy consumption (FFE) on cash holdings. Referring to low pollution emissions, less operational risk and a cheap source of energy, the more consumption of renewable energy reduces the motives of cash holdings. Primarily, the current analysis advocates an important policy regarding the utilization of renewable energy as industrial fuel inputs because it has a material impact on cash holdings and also ensures environmental sustainability.Practical implicationsThis study has equal policy outputs for industry officials, policy regulators and environmental economists. Corporate managers should do more focus on transforming the energy needs from non-renewable to renewable as such transformation can benefit in terms of both, i.e. environmental sustainability and low cash holdings.Originality/valueContemporary literature mainly highlights the determinants of energy consumption. However, it is less known how the consumption of specific energy sources affects the firm's cash-holding decisions. Thus, this study enriches both energy economics and financial economics literature by offering cutting-edge evidence on the sustainable role of REC in declining cash holdings.

Examining willingness to pay for energy futures in a fossil and renewable energy-rich locale

The debate over transitioning from fossil fuels to renewables often focuses on the trade-offs between fossil fuels' economic benefits and the environmental benefits of renewable energy. However, most of the extant literature has focused on the willingness to pay to increase or decrease reliance on a single, specific energy source. We implement a choice experiment in New Mexico focusing on tradeoffs between energy choice, employment, and greenhouse gas emissions within a policy context, controlling for heterogeneity across respondent groups. We find jobs are important across respondents. We also find statistically significant differences in respondent preferences for energy types based on geographic proximity to fossil fuel production and opinion about anthropogenic climate change. In many cases, preference impacts are asymmetric across respondent groups. This suggests that an energy policy with majority support may require a portfolio approach, resulting in an intricate design.

Sedation strategies for pulsed-field ablation of atrial fibrillation with monitored anesthesia care versus general anesthesia: a single-center experience

Abstract Funding Acknowledgements Type of funding sources: None. Background Atrial Fibrillation (AF) ablation has been performed successfully under different methods of anesthesia and varies between centers, from general anaesthesia (GA) to conscious sedation. Recently, a novel pulsed-field ablation (PFA, Farapulse) technology based on non-thermal ablation has become available for clinical use. To date, no structured sedation strategy has been implemented for this specific energy source. Purpose We sought to compare a GA protocol and a monitored anesthesia care (MAC) protocol used at a high-volume center, with special consideration on efficiency and optimization of mapping and ablation conditions. Methods All consecutive patients (pts) undergoing AF ablation with PFA at our center were included. Briefly, PFA was delivered by a protocol-directed PVI using 2kV with eight applications per vein, that is, four applications each in the basket and flower poses. The choice of anesthesia’s protocol depends on the preference and experience of operator and general conditions of the patient. The MAC protocol includes propofol as only anesthetic agent and analgesia with fentanyl. The GA protocol include propofol and sevofluorane as anesthetic agents and fentanyl and remifentanyl for analgesia. Anesthesia related complications (hypotension and hemodinamic instability, respiratory complications, postoperative nausea and vomit) operative pain, chest movements, operator and patient satisfaction have been reported. Data are reported as mean±DS. Results Thirty-six pts were included in this analysis, 28 (78%) indicated for ablation of paroxysmal AF and 8 (22%) of persistent AF. MAC protocol was applied in 16 (44%) procedures and GA protocol in 30 (56%) procedures. No differences were found in terms of procedural and management parameters according with these two strategies, that is MAC vs GA: 114±28min vs 121±19min for lab occupancy time, p=0.3521; 66±14min vs 81±25min for total support time, p=0.0683; 63±9min vs 63±18min for skin-to-skin time, p=0.3887; and 19±6min vs 20±5min for fluoroscopy time, p=0.3313, respectively). No major procedure-related adverse events were reported. Operative pain and chest movements were less in GA protocol, operator satisfaction was greater in GA protocol. No significant differences in post-operative nausea and vomit and patient satisfaction were found. Conclusion The adoption of a structured workflow with proper perioperative assessment during pulsed-field ablation of AF, both general anesthesia and monitored anesthesia care showed similar efficacy and safety profile.

Electricity accounting in life cycle assessment: the challenge of double counting

PurposeIn grid electricity consumption models, the location-based method uses regional average emission factors to account for environmental impacts. The market-based method is based on contractual agreements, verifying the exclusive claim on electricity from specific energy sources. An inconsistent application of these methods in life cycle assessment (LCA) and GHG accounting can lead to double counting. Especially, double counting electricity associated with rather low environmental impacts, such as renewable energy, might lead to impact underestimations. The aim of this paper is to identify, describe and propose solutions to double counting challenges.MethodsA four-step procedure is carried out. First, the specifications on grid electricity mix selection in frequently applied standards for LCA and GHG accounting are analysed. Besides the ISO norms for LCA (14040/44) and carbon footprinting (14064/67), the GHG Protocol and the Product and Organizational Environmental Footprint (PEF/OEF) are considered. Based on this analysis, challenges of double counting electricity from specific sources are identified. In the third step, potential solutions for avoiding double counting are proposed. The last research step consists of an illustrative case study to demonstrate the calculation of market-based electricity mixes and identify potential adjustments necessities for LCA application.Results and discussionA parallel application of the location-based and the market-based method poses the main double-counting challenge. Thus, avoiding double counting demands consistent method application throughout the whole life cycle. Whereas this is relatively straightforward for the location-based method, consistent market-based method application is more challenging. LCAs rely on average life cycle inventory processes, which mostly include location-based electricity mixes. However, for consistent market-based method application throughout the life cycle, electricity-related environmental impacts in the inventory system also need to be market-based. This would demand a partial recalculation of LCI datasets using market-based residual electricity mixes. Besides illustrating the calculation of market-based electricity mixes, the case study is used to identify and propose solutions for two main challenges for residual mix application in LCA: countries without residual mix and electricity under a double marketing ban.ConclusionDouble counting of electricity from specific energy sources is a challenge, since it can lead to under- or overestimations of environmental impacts. Both the location-based and market-based method can avoid double counting. However, parallel or inconsistent applications of both methods lead to double counting. In order to avoid double counting, there is a need to enable and use consistent electricity accounting rules in LCA and GHG accounting.

New evidence on the rural poverty and energy choice relationship

We combine a global micro level dataset that includes 17 different rural Sub-Saharan countries with satellite information about precipitation during the growing season to estimate the impact of economic conditions on energy choice. Differently from the existing literature, we aim to causally estimate the impact of household welfare variation on the likelihood of choosing a specific energy source. It is found, consistent with theory, that increases in income do determine an increase in the likelihood of using relatively cleaner and more efficient sources of fuel. We find, however, that this impact is quantitatively very small. Results hold conditional on assets, wealth and a large battery of controls and fixed effects. Policy implications are developed.

Recent Progress of Energy-Storage-Device-Integrated Sensing Systems

With the rapid prosperity of the Internet of things, intelligent human-machine interaction and health monitoring are becoming the focus of attention. Wireless sensing systems, especially self-powered sensing systems that can work continuously and sustainably for a long time without an external power supply have been successfully explored and developed. Yet, the system integrated by energy-harvester needs to be exposed to a specific energy source to drive the work, which provides limited application scenarios, low stability, and poor continuity. Integrating the energy storage unit and sensing unit into a single system may provide efficient ways to solve these above problems, promoting potential applications in portable and wearable electronics. In this review, we focus on recent advances in energy-storage-device-integrated sensing systems for wearable electronics, including tactile sensors, temperature sensors, chemical and biological sensors, and multifunctional sensing systems, because of their universal utilization in the next generation of smart personal electronics. Finally, the future perspectives of energy-storage-device-integrated sensing systems are discussed.

Attribute Preferences and Economic Value of Green Electricity in Pakistan

Huge reliance on thermal power for electricity generation, the power sector of Pakistan has become significant contributor to GHG emissions. Government has plans to improve and upgrade the electricity infrastructure through generating more electricity from renewable energy sources. In order to evaluate the economic benefits which people are expected to gain if different sources of green electricity are incre0ased in the system and their preferences for any specific renewable energy sources are aimed in this study. The objectives of this study were explored by employing choice experiment (CE). The respondents were divided into two broad categories of urban and rural. Three main sources of green electricity (Hydroelectricity, wind and solar) along with load shedding attribute were explored. The Conditional Logit Model and Mixed Logit Models were employed to identify the consumer’s preferences and estimation of the marginal values. Results showed that the urban and rural consumers chose solar as the most preferred source and marginal values for this source is 0.17 cents per kWh consumption and 0.19 cents per kWh consumption in urban and rural models respectively.

The triangle correlation among the impact on serum S100B protein release, incidence of the silent cerebral ischemic phenomena and pulsed field ablation for patients with atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: None. Backgrounds: Pulsed field ablation (PFA) represents a cardiac specific energy source for atrial fibrillation (AF) ablation. The correlation among this remarkable technique, the incidence of silent cerebral ischemic phenomena (SCIP), and the clinical impact on serum S100B release, a well-known neural injury relevant biomarker concomitant to denervation of the intrinsic cardiac autonomic nervous system during AF ablation, has been unclear. Aims This study thought to reveal the "triangle correlation" by investigating the serum S100B increase, incidence of SCIP on cerebral magnetic resonance imaging (MRI), and its interactive correlation in PFA using the FARAPULSE system. Methods and Results Pre- and postprocedural serum S100B was analyzed in a total of 85 patients who underwent AF ablation using the FARAPULSE PFA device. Cerebral MRI was performed subsequently 24-48 hours after procedure. All PVs (332 PVs) were successfully isolated solely with PFA. No additional left atrial mapping using other catheters was performed. The median overall serum S100B increase from the preprocedural value was 0.01μg/l (-0.02 – 0.04μg/l). Asymptomatic SCIP were detected on MRI in 10/53 patients (18.9 %). Of those, the patients with SCIP demonstrated a significantly higher S100B release (0.04, 0.02 – 0.16μg/l vs. without SCIP:0.01, -0.04 – 0.03μg/l, p = 0.0038). Receiver operating characteristic curve revealed a predictive cut-off point for SCIP of 0.04 μg/l (sensitivity:0.7, specificity: 0.49). Conclusions We revealed no clear detectable impact of PFA on S100B release, highlighting the cardioselectivity with limited concomitant denervation. SCIP was detected approximately in a one-fifth after procedures and was a potential confounder of the higher S100B increase.

The Potential of Using Renewable Energy Sources in Poland Taking into Account the Economic and Ecological Conditions

The aim of the manuscript was to present the collective results of research on the profitability of using various renewable sources in Poland with the greatest development potential. In the paper, the economic parameters of various investment projects were determined and calculated, i.e., Net Capital Value (NPV), Internal Rate of Return (IRR) and the Period of Return on Invested Capital (PBT). The economic assessment of the use of RES technologies was supplemented with the assessment of environmental benefits. The ecological criterion adopted in the study was the assessment of the potential and costs of reducing greenhouse gas emissions as a result of replacing fossil fuels with renewable energy technologies. On the basis of the constructed economic model to assess the profitability of investments, it has been shown that the analyzed projects will start to bring, depending on their type and technical specification, measurable economic benefits in the form of a reduction in the amount of energy purchased on an annual basis and environmental benefits in the form of reduction of carbon dioxide emissions to the atmosphere. Moreover, the calculations show a high potential for the use of certain renewable sources in Poland, which contributes to the fulfillment of energy and emission obligations towards the EU. The analyzes and research of the Polish energy market with the use of the presented models have shown that the project is fully economically justified and will allow investors to make a rational decision on the appropriate selection of a specific renewable energy source for their investment. The presented economic models to assess the profitability of investments in renewable energy sources can be successfully used in other countries and can also be a starting point for a discussion about the direction of energy development. Due to the lack of collective, original and up-to-date research on the domestic market, the manuscript provides the reader with the necessary knowledge regarding the legitimacy of using renewable energy sources, investment and environmental profitability.

Thermal management of thermoelectric generators for waste energy recovery

Energy savings motivated by economic and environmental reasons have brought attention to waste heat recovery technologies. Thermoelectric generators, previously employed as electric power generators in harsh conditions such as the found in space missions and remote ground locations, have arisen as an option to recover waste energy. Thermoelectric generators convert heat into electric power, but the low conversion efficiency of thermoelectric materials involves a challenge in the integration of thermoelectric generators to heat sources, as more energy losses than savings can be caused. As a result, the design process must be tailored to the system from which energy is to be recovered. This work fills the gap in previous reviewed literature, providing considerations focused on thermal management of heat sources for the design of thermoelectric generators and methods to evaluate specific energy sources and prototypes are presented. In addition, several applications were reviewed and main opportunities, advantages and drawbacks in different sectors are presented.

Vitamin D regulation of energy metabolism in cancer.

Vitamin D exerts anti-cancer effects in recent clinical trials and preclinical models. The actions of vitamin D are primarily mediated through its hormonal form, 1,25-dihydroxyvitamin D (1,25(OH)2 D). Previous literature describing in vitro studies has predominantly focused on the anti-tumourigenic effects of the hormone, such as proliferation and apoptosis. However, recent evidence has identified 1,25(OH)2 D as a regulator of energy metabolism in cancer cells, where requirements for specific energy sources at different stages of progression are dramatically altered. The literature suggests that 1,25(OH)2 D regulates energy metabolism, including glucose, glutamine and lipid metabolism during cancer progression, as well as oxidative stress protection, as it is closely associated with energy metabolism. Mechanisms involved in energy metabolism regulation are an emerging area in which vitamin D may inhibit multiple stages of cancer progression. LINKED ARTICLES: This article is part of a themed issue on New avenues in cancer prevention and treatment (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.12/issuetoc.

Flourishing energy harvesters for future body sensor network: from single to multiple energy sources.

SummaryBody sensor network (bodyNET) offers possibilities for future disease diagnosis, preventive health care, rehabilitation, and treatment. However, the eventual realization demands reliable and sustainable power sources. The flourishing energy harvesters (EHs) have provided prominent techniques for practically addressing the concurrent energy issue. Targeting for a specific energy source, wearable EHs with a sole conversion mechanism are well investigated. Hybrid EHs integrating different effects for a single source or multi-sources are attaining growing attention, for they provide another degree of freedom concerning a higher-level energy utility. Merging EHs with other functional electronics, diversified functional self-sustainable systems are developed, paving the way for the accomplishment of bodyNET. This review introduces the evolution of wearable EHs from a single effect to hybridized mechanisms for multiple energy sources and wearable to implantable self-sustainable systems. Last, we provide our perspectives on the future development of hybrid EHs to be more competitive with conventional batteries.

W jaki sposób rozwój indonezyjskiej nauki w zakresie odnawialnych źródeł energii skutecznie wspiera projektowanie polityki? Podróż w kierunku zrównoważonej energetyki

The aim to achieve the target of a 23% share of sustainable energies in the total Indonesia’s primary energy supply requires enormous amounts of works. Indonesia’s scientific knowledge production can support a successful transition to renewables. However, policy makers struggle to determine how the transition benefits from the scientific production on renewable. A bibliometric study using scientific publication data from the Web of Science (WoS) is used to probe how Indonesian scientific knowledge production can support the policy design for transition to sustainable energy. The seven focused disciplines are geothermal, solar, wind, hydro, bio, hybrid, and energy policy and economics. Based on the data from the above-listed disciplines, a deeper analysis is conducted, and implications to the policy design are constructed. The study reveals that bio energy is the focus of the research topics produced in Indonesia, followed by solar and hydro energy. Most RE research is related to the applied sciences. The innovation capability in the form of technology modifiers and technology adapters supports the transition to sustainable energy in Indonesia. The research on bio energy, however, is characterized by higher basic knowledge than research on solar and hydro energy. This suggests low barriers to the access to the resources and to the completion of bio research in Indonesia. Designing Indonesian energy policy by comprising discriminatively specific sustainable energy sources in the main policy instruments can therefore accelerate the sustainable transition and development.

재생에너지 정책수단 전환의 효과성 연구: 한국의 전환 사례 분석

While the policy intervention of each country for the promotion of renewable energy is strengthened, Korea introduced Feed-in Tariff (FIT) in 2002 to directly support the development of renewable energy. But in 2012, the shift of policy instrument that from FIT to Renewable Portfolio Standard (RPS) is occurred. This is a unique background that is currently found only in Korea, and new answers that focus on the outcomes of the shift of policy instruments are needed in addition to the existing discussion of comparison of FIT and RPS. Therefore, this study analyzed the change of policy efficiency after the shift to RPS using Data Envelopment Analysis(DEA) and Malmquist Index. In the result of analysis, a difference in the improvement of policy efficiency after in shift to RPS is found among each renewable energy source. This result is because renewable energy companies voluntarily entered the market only for energy sources that have secured technology or price competitiveness, and this indicates that the performance of renewable energy after the RPS shift has been concentrated on specific energy sources. As a result of this study, considering that the goal of renewable energy policy is to expand distribution and to drive growth engines, multi-faceted analysis is required in consideration of technology and market in selecting policy instruments.