Energy Glossary

New to the energy world? Been working in energy for decades, but are finding yourself overwhelmed by acronyms and new phrases. Use this up-to-date energy glossary to make sure you don't miss a beat in your next energy-related discussion.



AAQS - Ambient Air Quality Standards

AC - Alternating Current

ACA - Annual Charge Adjustment

ACEEE - American Council for Energy-Efficient Economy

AEE - Advanced Energy Economy

AFV - Alternative Fuel Vehicle

AGA - American Gas Association

AGC - Automatic Generation Control

AMI - Advanced Metering

AMRA - American Meter Reading Association

ANGA - America's Natural Gas Alliance

ANSI - American National Standards Institute

APE - Area of Potential Effect

API - American Petroleum Institute

APPA - American Public Power Association

APR - Actual Peak Reduction

AQCR - Air Quality Control Region

ARRA - American Reinvestment and Recovery Act (aka The Stimulus Package)

ASE - Alliance to Save Energy

ASTM - American Society for Testing and Materials

AVR - Automatic Voltage Regulator


BA - Balancing Authority

BACT - Best Available Control Technology

BCF - Billion Cubic Feet

BES - Bulk Electric System

BHE - Black Hills Energy

BPS - Bulk Power System

BTU - British Thermal Unit


C&I - Commercial and Industrial Customers

CAA - Clean Air Act

CAEM - Center for the Advancement of Energy Markets

CAFE - Corporate Average Fuel Economy Standards

CAZ - Combustion Area Zone (As in CAZ Testing)

CBL - Customer Baseline Load

CC - Combined Cycle Gas Turbine Electricity Generator

CCPP - Combined Cycle Power Plant

CDD - Cooling Degree Day

CEO - Colorado Energy Office (Formerly Governor's Energy Office)

CEQ - Council on Environmental Quality

CER - Certified Emission Reduction

CFS - Cubic Feet per Second

CH4 - Methane

CHP - Combined Heat and Power, aka Co-Generation

CNG - Compressed Natural Gas

CO - Carbon Monoxide

COOP - Cooperative Electric Association, aka REA

CO2 - Carbon Dioxide

CPI - Consumer Price Index

CPP - Critical Peak Pricing

CPS - Control Performance Standard

CREED - Colorado Center for Renewable Energy and Economic Development

CRT - Capacity Reservation Tariff

CT - Combustion Turbine


DADRP - Day Ahead Demand Response Plan

DARTP - Day Ahead Real Time Pricing

DC - Direct Current

DCLM - Direct Control Load Management

DF- Distribution Factor

DG - Distributed Generation

DLC - Direct Load Control

DO - Dissolved Oxygen

DOE - United States Department of Energy

DOT - United States Department of Transportation

DR - Demand Response

DRR - Demand Response Resources

DSO - Distribution System Operator

Dth - Dekatherm


ECIP - Energy Conservation Investment Program

ECPA - Electric Consumers Protection Act

EDRP - Emergency Demand Response Program

EE - Energy Efficiency

EEBC - Energy Efficiency Business Coalition

EEI - Edison Electric Institute

EER - Energy Efficiency Ratio

EERS - Energy Efficiency Resource Standard

EEPS - Energy Efficiency Performance Standard

EHV - Extra High Voltage

EIA - Energy Information Administration

EIS - Environmental Impact Statement

EPA - United States Environmental Protection Agency

EPRI - Electric Power Research Institute

ERA - DOE Economic Regulatory Administration

ESCO - Energy Services Company

ESI - Environmental Sustainability Index

ESS - Energy Storage System


FAC - Fuel Adjustment Clause

FACTS - Flexible Alternation Current Transmission System

FELCC - Firm Energy Load Carrying Capability

FERC - Federal Energy Regulatory Commission

FPA - Federal Power Act

FTC - Federal Trade Commission

FWPA - Federal Water Power Act


GAO - Government Accountability Office

GHG - Greenhouse Gas

GIC - Gas Inventory Charge

GRI- Gas Research Institute

GSF - Generator to Load Distribution Factor

GTCC - Gas Turbine Combined Cycle

GW - Gigawatt (one billion watts)

GWE - Gigawatt of Electric Energy

Gwh - Gigawatt Hours


HDD - Heating Degree Days

HERS - Home ENergy Rating Standard

hp - Horsepower

HPwES - Home Performance with Energy Star

HVAC - Heating, Ventilation, and Air Conditioning

HVDC - High Voltage Direct Current


IAQ - Indoor Air Quality

ICAP - Installed Capacity

ICE - Internal Combustion Engine

IEA - International Energy Agency

IER - Incremental Energy Rate

IGCC - Integrated Coal Gasification Combined Cycle

IHR - Incremental Heat Rate

ILP - Integrated Licensing Process

IOU - Investor Owned Utility

IPP - Independent Power Producer

IRP - Integrated Resource Planning

IRR - Internal Rate of Return

ISO - Independent System Operator

ITC - Investment Tax Credit


JRC - Joint Research Centre


kV - Kilovolt (One Thousand Volts)

KVA - One Thousand Volt Ampere

Kw - Kilowatt (One Thousand Watts)

KWE - Kilowatt Electric

kWh - Kilowatt Hour


LEVP - Low Emissions Vehicle Program

LIHEAP - Low Income Home Energy Assistance Program

LLNL - Lawrence Livermore National Laboratory

LMP - Locational Marginal Price

LNG - Liquified Natural Gas

LODF - Line Outage Distribution Factor

LOLE - Loss of Load Expectation

LPG - Liquified Petroleum Gas

LRG - Liquified Refinery Gases

LSF - Load Shift Factor

LWR - Light Water Reactor


MBD - Million Barrels per Day

MBR - Market Based Rates

MDD - Maximum Daily Delivery Obligations

MDDQ - Maximum Daily Delivery Quantity

MER - Maximum Efficiency Rate

MERC - Mobile Emission Reduction Credit

MMBTU - 1 Million British Thermal Units

MMCF - One Million Cubic Feet

MMCFD - One Million Cubic Feet per Dat

MMGAL - One Million Gallons

MOU - Memorandum of Understanding

MPG - Miles per Gallon

MSW - Municipal Solid Waste

Mtoe - One Million Tons of Oil Equivalent

Muni - Municipality or Municipal Utility Provider

MW - Megawatt (One Million Watts)

MWE - Megawatt Electric

MWh - Megawatt Hour


NAAQS - National Ambient Air Quality Standards

NAESB - North American Energy Standards Board

NAICS - North American Industry Classification System

NAP - National Action Plan

NARUC - National Association of Regulatory Utility Commissioners

NASUCA - National Association of Utility Consumer Advocates

NATC - Non-Recallable Available Transfer Capability

NBS - National Bureau of Standards

NEA - The National Energy Act of 1978

NEPA - National Environmental Policy Act

NGL - Natural Gas Liquids

NGV - Natural Gas Vehicle

NIETC - National Interest Electric Transmission Corridor

NOI - Notice of Intent

NOx - Nitrogen Oxides

NPV - Net Present Value

NRECA - National Association of Rural Electric Cooperatives

NREL - National Renewable Energy Lab


O&M - Operation and Maintenance Expenses

O3 - Ozone

OEM - Original Equipment Manufacturers

OFO - Operational Flow Order

OSHA - United States Department of Labor Occupational Safety and Health Administration

OTDF - Outage Transfer Distribution Factor


PCM - Project Cycle Management

PCT - Programmable Communicating Thermostat

PGA - Purchased Gas Adjustment

PLC - Power Line Communication

PLMA - Peak Load Management Association

PM - Particulate Matter

PNNL - Pacific Northwest National Laboratory

POD - Point of Delivery

PPA - Power Purchase Agreement

PPI - Producer Price Index

PPP - Purchasing Power Parity

PPR - Potential Peak Reduction

PSCo - Public Service Company of Colorado (aka Xcel Energy)

PTDF - Power Transfer Distribution Factor

PUC - Public Utility Commission

PV - Photovoltaic (Solar)

PVC - Photovoltaic Cell

PX - Power Exchange


QA - Quality Assurance (External Process)

QC - Quality Control (Internal Process)

QF - Qualifying Facility


R/P - Reserve on Production

RAP - Regulatory Assistance Project

RATC - Recallable Available Transmission Capability

RDF - Refuse Derived Fuel

REA - Rural Electric Association (aka Coop)

REC - Renewable Energy Credit

RES - Renewable Energy Source

RFI - Request for Information

RFP - Request for Proposals

RFQ - Request for Qualifications

RMU - Removal Units

ROE - Return of Equity

ROI - Return on Investment

RPM - Reliability Pricing Model

RTP - Real Time Pricing

RTU - Remote Terminal Unit


SCF - Standard Cubic Foot

SCO - Standard Cost Obligation

SEC - Securities and Exchange Commission

SEER- Seasonal ENergy Efficiency Ratio

SEFI - Sustainable Energy Finance Initiative

SFV - Straight Fixed Variable

SI - International System of Units

SIC - Standard Industrial Classification

SO2 - Sulfur Dioxide

SPP - Small Power Producer

SPR - Strategic Petroleum Reserve

SWEEP - Southwest Energy Efficiency Project


TBL - Transmission Business Line

Tcf - Trillion Cubic Feet

TCR - Total Cost Recovery (Mechanism)

TDU - Transmission Dependent Utility

TO - Transmission Owner

tow- Ton of Oil Equivalent

TOP - Transmission Operator

TRM - Transmission Reliability Margin

TTC - Total Transfer Capacity

TW - Terawatt (One Trillion Watts)

TWH - Terawatt Hour


U.S.C - United States Code

UHVAC - Ultra High Frequency Alternating Current

UHVDC - Ultra High Frequency Direct Current

URR - Ultimate Recoverable Resources

USCE - United States Army Corps of Engineers

US DOE - United States Department of Energy


V- Volt

VA - Volt-Ampere

var - Volt Ampere Reactive

VAWT - Vertical Axis Wind Turbine

VSA - Voltage Storage Analysis


W - Watt

WACOG - Weighted Average Cost of Gas

WEA - World Energy Assessment

WH - Watt Hour

WRI - World Resources Institute

WTG - Wind Turbine Generator

WY - Water Year

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