Power and Energy Commons^™

Assessment Of Hydrogen Adoption Readiness In Energy Sector Using Indicator-Based Analysis, Patcharee Penchan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Global environmental concerns have led countries like Japan and Thailand to seek alternative energy sources to meet environmental goals and country agenda. Hydrogen has been added to the energy agenda as a way to address the energy challenges and shape the country's future profile. This study analyzes the readiness of Japan and Thailand to adopt hydrogen energy technology by comparing indicators. Japan experienced in developing hydrogen energy projects, while Thailand is exploring the technology's potential. The research proposes a hydrogen-related indicator framework to evaluate a country's energy system in Japan and Thailand case. The study aims to identify indicators to …

ผลกระทบด้านความต้องการพลังงานของอาคารที่ออกแบบตามเกณฑ์เป็นสุข, จีรุฏฐ์ ตั้งมานะกิจ

Chulalongkorn University Theses and Dissertations (Chula ETD)

การวิจัยนี้มีวัตถุประสงค์เพื่อนำเสนอผลกระทบด้านความต้องการพลังงานของอาคารที่ออกแบบตามเกณฑ์อาคารที่มีสุขภาวะที่ดีโดยสถาบันอาคารเขียวไทยมีชื่อเกณฑ์”เป็นสุข” โดยการวิจัยนี้นำข้อมูลการประเมินประสิทธิภาพการใช้พลังงานทั้งอาคารกรณีศึกษาแบบปกติและอาคารกรณีศึกษาที่ปรับแบบให้สอดคล้องตามเกณฑ์เป็นสุข นำมาวิเคราะห์เปรียบเทียบตามมาตรฐานและหลักเกณฑ์ในการออกแบบอาคารเพื่อการอนุรักษ์พลังงาน โดยการใช้โปรแกรม Building Energy Code (BEC) Web-based ผลการศึกษาพบว่า อาคารกรณีศึกษาแบบปกติที่ใช้เป็นแบบอ้างอิงมีผลการประเมินประสิทธิภาพการใช้พลังงานผ่านเกณฑ์ตามข้อกำหนดของกฎกระทรวงฯ ทั้งแบบการประเมินรายระบบและการใช้พลังงานโดยรวม ส่วนกรณีอาคารเป็นสุขแบบที่ 1 ผ่านเกณฑ์ตามข้อกำหนดของกฎกระทรวงฯเฉพาะการใช้พลังงานโดยรวม แต่ระบบกรอบอาคารไม่ผ่านเกณฑ์การประเมินรายระบบ โดยที่ค่าการถ่ายเทความร้อนรวมของผนังในส่วนที่มีการปรับอากาศ (OTTV) เปลี่ยนแปลงเพิ่มขึ้น 13.86% เนื่องจากความต้องการของอาคารตามเกณฑ์เป็นสุข คือ การมีช่องเปิดที่มีขนาดใหญ่ขึ้นและมีกระจกหน้าต่างที่สว่างมากขึ้นเพื่อให้ได้รับแสงสว่างธรรมชาติที่มากขึ้น จึงนำความร้อนเข้าสู่ภายในอาคารผ่านกระจกหน้าต่างด้านนอกมากขึ้น โดยเฉพาะอย่างยิ่งหากไม่ได้ใช้กระจกกรอบอาคารประสิทธิภาพสูง แต่สำหรับค่าการใช้พลังงานโดยรวมของอาคารพบว่าอาคารเป็นสุขแบบที่ 1 ยังสามารถผ่านเกณฑ์ตามข้อกำหนดของกฎกระทรวงฯ เนื่องจากการประหยัดพลังงานจากการใช้ไฟฟ้าแสงสว่าง สำหรับอาคารเป็นสุขแบบที่ 2 ผ่านเกณฑ์ตามข้อกำหนดของกฎกระทรวงฯ ทั้งแบบการประเมินรายระบบและการใช้พลังงานโดยรวม

Superhalogen-Based Li-Rich Anti-Perovskite Superionic Conductors, Md Mominul Islam

Electronic Theses and Dissertations

Solid-state batteries are being widely explored to meet next-generation energy storage demand with a great potentiality of achieving high energy and power densities at All-solidstate Lithium-ion batteries (LIBs). In recent years, electronically inverted lithium-rich antiperovskite (LiRAP) solid electrolytes with the formula Li3OX, where X is a halogen or mixture of halogens have appeared as a prospective alternative of the commercially available flammable and corrosive organic liquid electrolytes because of their high ionic conductivity, structural variety, and wide electrochemical window. Here, For the first time, we have successfully formulated and synthesized a completely new class of super halogen based double anti-perovskite …

Optimization Based On Movable Damped Wave Algorithm For Design Of Photovoltaic/ Wind/ Diesel/ Biomass/ Battery Hybrid Energy Systems, Mohammed Kharrich, Salah Kamel, Mamdouh Abdel-Akher, Ahmad Eid, Hossam Zawbaa, Jonghoon Kim

Articles

The actual energetic situation has several challenges such as pollution, the rarefaction of fossil fuel and the dangers of nuclear. Renewable sources are proposed as a solution and suggested, such as a cost-effectiveness system. The paper deals with the problem of feeding a domestic load with electricity which should respect the ecologies factors, so this work is a design problem of the hybrid renewable energy systems; PV/biomass, PV/diesel/battery, PV/wind/diesel/battery, and wind/diesel/battery to choose the best one of them which feed the load with the lowest cost. The study’s goal is to design a microgrid system by the minimization of the …

A Soft-Switched Three-Port Dc-Dc Converter For A Pv/ Battery System, Mohamedelfatih Dosa

All Graduate Theses, Dissertations, and Other Capstone Projects

This thesis proposed a soft-switched three-port bidirectional DC-DC converter for managing the power flow of a photovoltaic (PV) and battery system. The proposed converter consists of three ports connected to a PV panel, battery, and load. These three ports are interfaced through the high-frequency transformer and use phase-shift control to achieve soft-switching for all converter switches. Compared with the traditional multiport converters, the proposed three-port converter uses the least number of power switches, and zero-voltage switching (ZVS). Simulation and experimental results validate the design and effectiveness of soft switching and power flow control. The converter can work in different scenarios …

Sizing Considerations For Ev Dynamic Wireless Charging Systems With Integrated Energy Storage, Donovin Lewis, Huangjie Gong, Gregory D. Erhardt, Rong Zeng, Omer Onar, Veda Prakash Galigekere, Burak Ozpineci, Dan Ionel

Power and Energy Institute of Kentucky Faculty Publications

Roadways with dynamic wireless charging systems (DWCS) enable charge-sustaining in-motion EV charging, which can reduce charging idle time while increasing range capabilities. Spatially distributed transmitter coils are controlled in response to traffic load that varies significantly minute to minute with high power levels, very short charging time, and low system utilization like wind turbine power. Traffic load estimation and localized analysis may guide effective sizing and topology adoption for feasible and scalable DWCS deployment. DWCS traffic load approximation is reviewed with measured Automated Traffic Recorder (ATR) data and statistical distributions being used to create a synthetic load analyzed using proposed …

Modeling And Control Of Direct-Conversion Hybrid Switched-Capacitor Dc-Dc Converters, Ziyu Xia

Dartmouth College Ph.D Dissertations

Efficient power delivery is increasingly important in modern computing, communications, consumer and other electronic systems, due to the high power demand and thermal concerns accompanied by performance advancements and tight packaging. In pursuit of high efficiency, small physical volume, and flexible regulation, hybrid switched-capacitor topologies have emerged as promising candidates for such applications. By incorporating both capacitors and inductors as energy storage elements, hybrid topologies achieve high power density while still maintaining soft charging and efficient regulation characteristics. However, challenges exist in the hybrid approach. In terms of reliability, each flying capacitor should be maintained at a nominal `balanced' voltage …

Intrinsically Mode Reconfigurable Load Modulation Balanced Amplifier Leveraging Transistor's Analog-Digital Duality, Niteesh Bharadwaj Vangipurapu

Electronic Theses and Dissertations, 2020-2023

The communication schemes have rapidly changed the face of the human means of communication. The evolution from one generation to another has triggered many challenges on the design methodologies of RF designers. As the evolution ensued, the spectrally efficient modulation schemes have resulted in the substantial rise of PAPR, the peak-to-average power ratio. To enable the efficient amplification of the high PAPR signals, this thesis explores the areas of Load modulated Balanced amplifiers that can be inherently reconfigured to achieve a better efficiency than the conventional RF power amplifiers that see a significant drop in the efficiency as the signal …

Broadband Power Amplifier Design With High Power, High Efficiency And Large Back-Off Range, Yuchen Cao

Electronic Theses and Dissertations, 2020-2023

As modern communication system technology develops, the demand for devices with smaller size, higher efficiency, and larger bandwidth has increased dramatically. To achieve this purpose, a novel architecture of load modulated balanced amplifier (LMBA) with a unique load-modulation characteristic different from any existing LMBAs and Doherty power amplifiers (DPAs) was presented, which is named as Pseudo-Doherty LMBA (PD-LMBA). Based on a special combination of control amplifier (carrier) and balanced amplifier (peaking) together with proper phase and amplitude controls, an optimal load-modulation behavior can be achieved for PD-LMBA leading to maximized efficiency over extended power back-off range. More importantly, the efficiency …

Fabrication Of Piezoelectric Field Effect Transistors For Acoustic Signal Detection, Luke Minks

Electronic Theses and Dissertations, 2020-2023

In this study, a standard bulk FET design is fabricated with a piezoelectric gate, allowing a microwave-frequency voltage signal to be transmitted from a transducer to the transistor via acoustic conduction through the substrate. Using a single polycrystalline aluminum nitride film as the piezoelectric material, microwave-frequency piezoelectric transducers were fabricated in parallel with piezoelectric FETs. These device pairs function by generating high frequency acoustic waves in the substrate via application of AC voltage to the transducers; the transistors then recover these signals by detecting these waves in their gates via the piezoelectric film, reproducing an attenuated version of the original …

Empirical Comparison Of Machine Learning Methods For Wind Power Predictions, Sidny M. Stewart

EWU Masters Thesis Collection

No abstract provided.

Hydrogen And Peer-To-Peer Energy Exchanges For Deep Decarbonization Of Power Systems, Hamed Haggi

Electronic Theses and Dissertations, 2020-2023

Decreasing costs of renewable energy resources and net-zero emission energy production policy, set by U.S. government, are two preeminent factors that motivate power utilities to deploy more system- or consumer-centric distributed energy resources (DERs) to decarbonize electricity production. Since, deep energy decarbonization cannot be achieved without high penetration of renewable energy sources, utilities should develop and invest in new business models for power system operation and planning during the energy transition. Considering the pathways to deeply decarbonize power systems, first, this dissertation proposes a novel hierarchical peer-to-peer (P2P) energy market design in active distribution networks. The framework integrates the distributional …

Heuristic Algorithms For Transmission Switching To Reduce Load Shedding, Tanveer Hussain

Electronic Theses and Dissertations

No abstract provided.

Efficient Numerical Optimization For Parallel Dynamic Optimal Power Flow Simulation Using Network Geometry, Rylee Sundermann

Electronic Theses and Dissertations

In this work, we present a parallel method for accelerating the multi-period dynamic optimal power flow (DOPF). Our approach involves a distributed-memory parallelization of DOPF time-steps, use of a newly developed parallel primal-dual interior point method, and an iterative Krylov subspace linear solver with a block-Jacobi preconditioning scheme. The parallel primal-dual interior point method has been implemented and distributed in the open-source PETSc library and is currently available. We present the formulation of the DOPF problem, the developed primal dual interior point method solver, the parallel implementation, and results on various multi-core machines. We demonstrate the effectiveness our proposed block-Jacobi …

State Level Trends In Renewable Energy Procurement Via Solar Installation Versus Green Electricity, Eric Michael Hanson

Masters Theses

“In the past 5 years, consumer options for procuring renewable energy have increased, ranging from rooftop solar installation to utility green pricing to Community Choice Aggregation. These options vary in terms of costs and benefits to the consumer as well as grid integration implications. However, little is known regarding how the presence of a wide range of options for utility-scale renewable procurement affects demand for distributed residential solar installations. In theory, there are three possible relationships, (1) positive correlation, where utility-scale and distributed resources complement each other to increase overall production, (2) negative correlation, where utility-scale and distributed resources are …

Wireless Power Transfer In Autonomous Mobile Microgrids, Carl Greene

Dissertations, Master's Theses and Master's Reports

The ability to autonomously dock unmanned ground vehicles plays a key role in mobile micro-grids, where efficient power transfer is paramount. The approach utilized in this work allows for near-field wireless power transfer in remote locations with minimal support. Establishing a micro-grid power system connection autonomously using wireless power eliminates the arduous task of designing a complex, multiple degrees of freedom (MDOF) robotic arm. The work presented in this thesis focuses on both the hardware and software within the micro-grid system. This particular near-field wireless system consists of a primary and secondary set of modules, comprised of Litz wire coils, …

Artificial Solid Electrolyte Interface With Superhalogen-Based Double Antiperovskite Li6os(Bh4)2 Materials For Dentrite-Free And Stable Lithium Metal Batteries, Gazi Mahfujul Alam

Electronic Theses and Dissertations

Lithium (Li) metal is regarded as the most propitious anode material for next-generation battery technologies owing to its incredibly high theoritical capacity (3860 mAh g-1) and the most negative electrochemical equilibrium potential (-3.04 V vs standard hydrogen electrode). However, the practical implementation of Li anode in commercial lithium batteries is severely inhibited by the unstable solid liquid interfaces resulting from the ultrahigh reactivity, which leads to dendrite growth, low coulombic efficiency, extreme volume fluctuation, and even safety concerns. For a stable and efficient lithium anode to build next generation Li metal battery, in this thesis, we have tried to solve …

Implementation And Usage Of Low-Cost Turbines For Power Generation In Water Networks, Luis Javier Ortiz Osornio

All Graduate Theses, Dissertations, and Other Capstone Projects

The following APP is part of an investigation and development, carried out to design, and implement a hydroelectric turbine of horizontal axis, in order to generate electrical energy in rural areas, utilizing existing infrastructure or natural waterways such as irrigation canals, piping, rivers and streams. Every industrialized country, as well as, most of the developing nations, have a stake in agriculture and thus access to the infrastructure required for irrigation purposes. Artificial irrigation canals offer advantages such as a clean continuous flow, with the possibility of flow regulation: this together with their vast availability as agricultural infrastructure constitute the main …

Autonomous Wildfire Detection System, Matthew Pyle, Nick Garrett

Williams Honors College, Honors Research Projects

According to the National Fire Protection Association Journal, federal wildfire suppression costs in the United States have risen from an annual average of about $425 million from 1985 to 1999 up to $1.6 billion from 2000 to 2019. On average, more than 200,000 acres in the United States are burned per year due to wildfires, with more than 700,000 acres burned in 2020 alone. With the risk of wildfire ever rising, there is a need for better early detection of remote wildfires, as existing methods often include long delays like satellites or rely on human lookout towers. The objective is …

Smart Kettlebell, Cole Russell, Patrick Davis, Ryan Deboer, Isaac Stecker

Williams Honors College, Honors Research Projects

The purpose of design team 08’s senior design project is to create and implement a workout device that will be able to calculate the caloric expenditure, repetitions, and length of a workout. Once the duration of a workout is completed, the user metrics will be communicated from the kettlebell system to a user application via Bluetooth. The caloric expenditure will be used using the data that is provided from the accelerometer. The duration of the workout will be controlled using a push button that is connected to the kettlebell system that will allow for the start and stop of a …

Stability Approximation Method For Pulse Loads In Power Electronic Systems, Eduardo A. Marmol D

Dissertations, Master's Theses and Master's Reports

Pulse loads on power electronic distribution systems are becoming very popular nowadays as the components of ships and airplanes are moving to more electric power. However, the pulse loads have a destabilizing effect on the power distribution system. Usually, the method used to study the stability of this type of system are small-signal analyses and are based on a system where the load is modeled as a constant. Since DC-DC systems with pulsed loads are very nonlinear, a small-signal analysis does not provide helpful information related to the stability of the system. The work presented in this thesis focuses on …

Development Of Dc Circuit Breakers For Medium-Voltage Electrified Transportation, Trevor Morgan Arvin

Theses and Dissertations--Electrical and Computer Engineering

Medium-voltage DC (MVDC) distribution is an enabling technology for the electrification of transportation such as aircraft and shipboard. One main obstacle for DC distribution is the lack of adequate circuit fault protection. The challenges are due to the rapidly rising fault currents and absence of zero crossings in DC systems compared to AC counterparts. Existing DC breaker solutions lack comprehensive consideration of energy efficiency, power density, fault interruption speed, reliability, and implementation cost.

In this thesis, two circuit topologies of improved DC circuit breakers are developed: the resonant current source based hybrid DC breaker (RCS-HDCB) and the high temperature superconductor …

Models And Optimal Controls For Smart Homes And Their Integration Into The Electric Power Grid, Huangjie Gong

Theses and Dissertations--Electrical and Computer Engineering

Smart homes can operate as a distributed energy resource (DER), when equipped with controllable high-efficiency appliances, solar photovoltaic (PV) generators, electric vehicles (EV) and energy storage systems (ESS). The high penetration of such buildings changes the typical electric power load profile, which without appropriate controls, may become a “duck curve” when the surplus PV generation is high, or a “dragon curve” when the EV charging load is high. A smart home may contribute to an optimal solution of such problems through the energy storage capacity, provided by its by battery energy storage system (BESS), heating, ventilation, and air conditioning (HVAC) …

Determining Power System Fault Location Using Neural Network Approach, Edward O. Ojini

Theses and Dissertations--Electrical and Computer Engineering

Fault location remains an extremely pivotal feature of the electric power grid as it ensures efficient operation of the grid and prevents large downtimes during fault occurrences. This will ultimately enhance and increase the reliability of the system. Since the invention of the electric grid, many approaches to fault location have been studied and documented. These approaches are still effective and are implemented in present times, and as the power grid becomes even more broadened with new forms of energy generation, transmission, and distribution technologies, continued study on these methods is necessary. This thesis will focus on adopting the artificial …

Hourly Dispatching Wind-Solar Hybrid Power System With Battery-Supercapacitor Hybrid Energy Storage, Pranoy Kumar Singha Roy

Theses and Dissertations--Electrical and Computer Engineering

This dissertation demonstrates a dispatching scheme of wind-solar hybrid power system (WSHPS) for a specific dispatching horizon for an entire day utilizing a hybrid energy storage system (HESS) configured by batteries and supercapacitors. Here, wind speed and solar irradiance are predicted one hour ahead of time using a multilayer perceptron Artificial Neural Network (ANN), which exhibits satisfactory performance with good convergence mapping between input and target output data. Furthermore, multiple state of charge (SOC) controllers as a function of energy storage system (ESS) SOC are developed to accurately estimate the grid reference power (P_Grid,ref) for each dispatching period. …

Parametric Average-Value Modeling, Simulation, And Characterization Of Machine-Rectifier Systems, Isuje Ojo

Theses and Dissertations--Electrical and Computer Engineering

There are many techniques for modeling and simulation of synchronous machine-rectifier systems. The more common approaches are the detailed and average-value modeling techniques. The detailed simulation technique takes into account the details of the diode switching and is both very accurate and very expensive in terms of computational resources. To alleviate this disadvantage, the average-value modeling technique is often utilized. In this approach, the details of diode switching are neglected or averaged. In that light, the work presented herein proposes a unique saliency-sensitive parametric average-value model (SSPAVM) of the synchronous machine-rectifier system. This model extends existing parametric average-value models to …

การวิเคราะห์ฉากทัศน์สำหรับศักยภาพชีวมวลของการผลิตไฟฟ้าจากวัสดุเหลือทิ้งทางการเกษตรในประเทศไทย, ธัญชนก เชิดชู

Chulalongkorn University Theses and Dissertations (Chula ETD)

งานวิจัยนี้มีวัตถุประสงค์เพื่อวิเคราะห์ฉากทัศน์ศักยภาพชีวมวลของการผลิตไฟฟ้าจากวัสดุเหลือทิ้งทางการเกษตรในประเทศไทย ภายใต้การวิเคราะห์ปัจจัยที่ทำให้เกิดผลกระทบและปัจจัยที่มีแนวโน้มที่จะมีการเปลี่ยนแปลง โดยการวิเคราะห์ได้ใช้เครื่องมือในการประเมินปัจจัยภายนอกต่างๆ ด้วยการวิเคราะห์ STEEP Analysis และทำการจัดลำดับปัจจัยเพื่อพิจารณาเลือกสถานการณ์ ที่ถูกกำหนดด้วยปัจจัยที่ทำให้เกิดผลกระทบและปัจจัยที่มีแนวโน้มที่จะมีการเปลี่ยนแปลงมากที่สุด พบว่าปัจจัยสำคัญที่ทำให้เกิดผลกระทบ (Impact) และมีแนวโน้มที่จะเกิดการเปลี่ยนแปลง (Uncertainty) ต่อฉากทัศนศักยภาพชีวมวลของการผลิตไฟฟ้าจากวัสดุเหลือทิ้งทางการเกษตรในประเทศไทย ได้แก่ ปัจจัยด้านการสนับสนุนนโยบายจากภาครัฐ เช่น อัตรารับซื้อไฟฟ้าจากชีวมวลในรูปแบบ Feed-in Tariff และปัจจัยด้านต้นทุนการผลิตไฟฟ้า เช่น ต้นทุนค่าเชื้อเพลิงชีวมวล ต้นทุนค่าการสร้างและค่าใช้จ่ายในการดำเนินการ ทั้งนี้ ได้กำหนดตัวชี้วัดสำหรับการติดตามและตรวจสอบสถานการณ์ ซึ่งเป็นปัจจัยเชิงปริมาณ ได้แก่ การวิเคราะห์ศักยภาพชีวมวลของการผลิตไฟฟ้าจากวัสดุเหลือทิ้งทางการเกษตร และการวิเคราะห์ต้นทุนส่วนเพิ่มในการลดก๊าซเรือนกระจก (Marginal Abatement Cost : MAC) เพื่อสะท้อนให้เห็นถึงการวิเคราะห์ศักยภาพเชิงปริมาณในแต่ละสถานการณ์ภายใต้เงื่อนไขของปัจจัยขับคลื่อน โดยได้แบ่งออกเป็น 3 สถานการณ์ ซึ่งพบว่า ศักยภาพชีวมวลของการผลิตไฟฟ้าจากวัสดุเหลือทิ้งทางการเกษตร มากที่สุด 38,376 เมกะวัตต์ รองลงมา ได้แก่ 24,940 เมกะวัตต์ และ 10,596 เมกะวัตต์ ตามลำดับ ในส่วนของการวิเคราะห์ต้นทุนส่วนเพิ่มในการลดก๊าซเรือนกระจก อยู่ระหว่าง -980 ถึง 131 บาท/ตันคาร์บอนไดออกไซด์เทียบเท่า

Use Of Battery Systems For Var Support In Con Edison’S Distribution Network/Substation, Elihu Nyemah

Dissertations and Theses

Battery Energy Storage System (BESS) can facilitate the integration of Distributed Energy Resources (DER) and help create a more reliable grid by providing multiple services including reactive power (VAR) support. This research will investigate the use of smart inverters to provide VAR support, assess the impact it has on the lifetime of a BESS and determine how the adverse effects (if any) can be mitigated/eliminated. To achieved this, a 7.5MW/30MWh grid connected BESS located at Con Edison substations have been modeled in MATLAB/Simulink. Preliminary assessment of the system showed that DC current to/from the battery is oscillating (non-zero) during reactive …

The Capabilities And Limitations Of Flywheel-Based Energy Storage System Pertaining To Subways In The Event Of A Power Outage, Jaskaran Singh

Dissertations and Theses

In the city that never sleeps, power outages or blackouts can be a shock, especially if you are on a train amid one. For example, during the infamous 2003 blackout, thousands of people were left stuck and stranded in parts of Northeastern United States. In particular, with no trains or buses in service throughout the 5 boroughs of NYC, those stranded essentially had no way to go back home. Hotels, terminals, and airports alike became places of camping as the city seemed to come to a halt. For the sake of public safety and transit efficiency, this study explores a …

An Efficient Ar Model-Based Method For The Detection Of Forced Oscillations In Power Networks: Implementation And Analysis, Maria Waleska Suarez

Graduate Theses, Dissertations, and Problem Reports (ETD)

An active research topic is the detection of various oscillations that may lead to instability and potential disruption in the operation of a power network. Forced Oscillations (FOs) play a unique role in power system stability among various oscillations. They are perturbances that change the system’s state and are caused for many reasons, including but not limited to persistent load changes and oscillatory load or generation, fault, triplane, and other mechanical anomalies. These factors can hugely affect the power grid by either increasing or decreasing the amplitude, causing corrupt modes leading to blackouts, affecting the equipment involved, delivering poor power …