Glossary & Acronyms

glossary & acronyms

The energy industry is full of acronyms – here’s a list to help you navigate.


A (Top)

AC – Alternating Current

Act 129 (PA) – Act 129 of 2008 provides Pennsylvania electric utility consumers opportunities to take energy efficiency and conservation to the next level. The General Assembly enacted Act 129 to require Pennsylvania’s seven largest electric distribution companies (EDCs) to develop energy efficiency and conservation plans (EE&C) and adopt other methods of reducing the amount of electricity consumed by customers.

The General Assembly charged the Pennsylvania Public Utility Commission (PUC) with implementing Act 129 and guiding consumers and electric utilities toward achieving the legislation’s overall goals of reducing energy consumption and peak electric demand. The PUC is implementing the Act in phases that address EDC responsibilities to implement EE&C programs; smart meter technology; time-of-use rates; real-time pricing plans; default service procurement; market misconduct; alternative energy sources; and cost recovery. The schedule for putting into practice this landmark legislation, while aggressive, is reflective of the immediacy of the energy challenges the Commonwealth is addressing.

In October 2009, the PUC approved plans from seven Pennsylvania EDCs – Allegheny Power Co.; Duquesne Light Co.; Metropolitan Edison Co.; PECO Energy Co.; Pennsylvania Electric Co.; Pennsylvania Power Co. and PPL Electric Utilities Corp. – detailing how the companies intend to achieve consumption and peak demand reductions. Additional details can be found at

ASHRAE – American Society of Heating Refrigeration & Air Conditioning Engineers

Avoided Cost – The cost a utility would incur to generate its next unit of energy or power. Avoided cost rates have historically been used as the power purchase price utilities offer Qualifying Facilities

B (Top)

BCF – Billion Cubic Feet

BTU – The British thermal unit (BTU or Btu) is a unit of heat energy used in the U.S. In most other areas, it has been replaced by the SU unit, the Joule (J). A Btu is defined as the amount of heat required to raise the temperature of one pound of water by 1 degree Fahrenheit. In the energy world, we typically discuss energy content in terms of Million Btu, or MMBtu.

C (Top)

Capacity – The amount of power that a generator can produce at a point in time, usually reported in MW. The maximum capacity is the amount of power that can be output when the plant is running “full out”.

Capacity Factor – Ratio of the actual output of a power plant over a period of time and its output if it had operated at full capacity in that time period. This is calculated by totaling the energy the plant actually produced and dividing it by the energy it would have produced if running the entire time at full capacity.

CNG – Compressed Natural Gas

Cogeneration – the sequential production and use of heat and power from a power plant

Co-op – A cooperative electric utlity, usally based in rural areas. Co-ops are owned by the members.

CSP – Curtailment Service Provider

CT – Current Transformer

Current – (Ampere, Amp) (I) = Current is the amount of electricity flowing in a circuit past a given point. Like the flow of water.

D (Top)

DC – Direct Current

Demand – Electric demand (load) is the amount of electricity you require at an instantaneous point in time. When you turn on an electric appliance, a “demand” for power is created. This instantaneous amount of electricity demand is measured in kilowatts (kW).

Demand Charge – some utility companies also impose an additional charge based on the maximum amount of power you draw at any one time. This is called a demand charge.

Demand Side Management – utility programs designed to reduce customer demand (kW).

DG – Distributed Generation. Small-scale power generation systems typically located on a customer site. Typically 3 kW – 10 kW in scale. The unit can be stand alone or grid connected.

Distribution System – The poles, wire and transformers used to deliver electric energy from a bulk power supplier to the consumer.

DOE – Department of Energy

DR – Demand Response

DSM – Demand Side Management

DSR – Demand-Side Response

Dth – Dekatherm (equivalent to 1 MMBTU)

E (Top)

EDC – Electric Distribution Company

EDI – Electronic Data Interchange

EEI – Edison Electric Institute

EER – Energy Efficiency Ratio

EGS – Electric Generation Supplier

EHV – Extra High Voltage

Electrical Energy – The generation or use of electric power (W) over as period of time (h), often expressed in kilowatt-hours (kWh), megawatt-hours (MWh) or gigawatt-hours (GWh).

EMF – Electric Magnetic Fields

EMS – Energy Management System

Energy – the ability to do work (Joules, Btu or kWh)

EPA – Environmental Protection Agency

EPAct – National Energy Policy Act of 1992

EPAct – Energy Policy Act of 2005

EPRI – Electric Power Research Institute

ESCO – Energy Service Company

F (Top)

Federally owned utility – Non profit entity that is owned by the federal government and primarily sells bulk power to other power entities. The Tennessee Valley Authority (TVA) is an example. Federal power marketing administrations (PMA’s) often transmit the power. Primarily produce and distribute hydropower.

FERC – Federal Energy Regulatory Commission

FPPL – Forecast Period Peak Load

FPR – Forecasted Pool Requirement

G (Top)

Genco – Generation Company

Generating Station – a power plant. Can be owned by just about anybody including utilities and non-utilities. This is a central station verses distributed.

Generation – The process of producing electric energy by transforming other forms of energy (Coal, Hydro, Nat Gas, etc.); also, the amount of electric energy produced, usually expressed in mega watt-hours (MWh). Generation is the first step in the process of delivering electricity to consumers (2nd – Transmission & 3rd Distribution).

Generation & Transmission Co-op (G&T) – Bulk power producer and transmitter of electricity. Usually, co-ops and munis are “all requirements” customers of a G&T.

Green Power – Electricity produced by sources that are less harmful to the environment than fossil fuels. Generally includes solar, wind, geothermal, biomass, and small hydroelectric. It is often sold through a utility Green Pricing Program.

Green Pricing – A utility based program whereby renewable energy is sold to consumers or other utilities at a premium. This is usually a voluntary program.

Grid – A network of transmission and distribution lines used to deliver electricity

GRT – Gross Receipts Tax

GW – Gigawatt = 1 billion watts = 1,000 MW.

H (Top)

Heat Rate – (Btu/kWh) A measure of the efficiency of a power plant. The amount of energy it takes to produce a unit of electricity. The conversion factor of a 100% efficient plant (e.g. – electric heater) is: 3,413 Btu – 1 kWh. The lower the heat rate, the better.

HVAC – Heating Ventilation and Air Conditioning

Hz – Hertz

I (Top)

ICAP – Installed Capacity Obligation

IEEE – Institute of Electrical and Electronics Engineers, Inc.

IOU – Investor Owned Utility (e.g. – PPL Electric Utilities). Owned by investors or stockholders. Generates, transmits, and distributes electricity to consumers and other utilities. Regulated by FERC, EPA and state Public Utilities Commissions. “Monopoly” service territories.

IPP – Independent Power Producer which is also called a Non-Utility Generator (NUG). A power plant owned not by a utility but by an investor or some other entity (Tribe, company, city, military base).

ISO – An Independent System Operator is a FERC-regulated control area operator of the ISO transmission grid. i.e. PJM

J (Top)

K (Top)

kV – kilovolt

KVA – kilovolt-ampere (transformer size rating)

KVAR – kilovolt-ampere reactive

kW – kilowatt = 1,000 watts.

kWh – kilowatt-hour. The basic unit of electric energy equal to one kilowatt of power used for a period of one hour.

L (Top)

LA – Load Aggregator

LDC – Local Distribution Company

Line Losses – Energy waste resulting from the transmission of electrical energy across power lines

LMP – Locational Marginal Pricing

LNG – Liquified Natural Gas

Load – The amount of electric power required to meet customers’ demand at any given time, expressed in kilowatts (kW) or Megawatts (MW)

Load Factor – The ratio of electrical demand to usage over time

Locational Marginal Price – The price assessed for congestion costs to a node.

LSE – Load Serving Entity

LTC – Load Tap Changing

M (Top)

Mcf – Thousand cubic feet of natural gas. More or less = 1 MMBtu.

MMBtu – 1 million British Thermal Unit

MOC – Market Operations Center

Muni – A municipality owned utility (e.g. – Ephrata Borough in Lancaster County)

MVAR – Mega Volt Amperes Reactive

MW – Megawatt = 1 million watts = 1,000 kW

MWd – Megawatt-day

N (Top)

NEMA – National Electrical Manufacturers Association

NEPA – National Energy Policy Act 1992

NERC – North American Electric Reliability Council, the organization consisting of all electric grids in North America.

Net Metering – Net metering is a policy for consumers who own, small, renewable energy facilities, such as wind or solar. “Net”, in this context, is used in the sense of meaning “what remains after deductions” – in this case, the deduction of any energy outflows from metered energy inflows. Under net metering, a system owner receives retail credit for at least a portion of the electricity they generate. The ideal has your existing electrical meter spinning backwards, effectively banking excess electricity production for future credit. In reality, the rules vary significantly by utility: if net metering is available, if and how long you can keep your banked credits, how much the credits are worth (retail/wholesale), etc.

Nodal Market – A method of assessing congestion costs to nodes within zones. Currently, in the zonal market, costs within each zone are socialized based on the size of each generator’s load. In a nodal market, these costs would be individually assessed based on a smaller node.

NITS – Network Integrated Transmission Service

NPV – Net Present Value

NRC – Nuclear Regulatory Commission

NUG – Non-Utility Generator

NYMEX – New York Mercantile Exchange

O (Top)

O&M – Operation and Maintenance Expenses

OATT – Open Access Transmission Tariff

OCB – Oil Circuit Breaker

OSHA – U.S. Department of Labor Occupational Safety and Health Administration

P (Top)

PCB – Polychlorinated biphenyls

Peak Load – The maximum expected load for a given period of time.

PJMPJM Interconnection, LLC (“Pennsylvania-New Jersey-Maryland”) electric interconnection responsible for ensuring reliability for most of the mid-Atlantic region

POLR – Provider of Last Resort, a company that serves as the interim provider for retail electric power

Power – (Watt, W) (P) = current x voltage; P=I*V. It is the rate at which work is done. This is an instantaneous measure at a given point in time.

PT – Potential Transformer

PTC – Price to Compare

PUC – (Pennsylvania) Public Utilities Commission

PURPA – Federal Public Utilities Regulatory Act of 1978

PV – Photovoltaic

Q (Top)

QF – Qualifying facilities are a distinct class of energy producers which consists of either small-scale producers who normally self-generate energy for their own needs but may have occasional or frequent surplus energy. Qualifying facilities were first classified in 1978 with the establishment of the Public Utility Regulatory Policies Act (PURPA), a piece of legislation which was intended to encourage more efficient and environmentally friendly energy production in the United States.

R (Top)

REC’s – Renewable Energy Certificates. Also called Green Tags, Renewable Energy Credits, or Tradable Renewable Certificates (TRC). Tradable environmental commodities that represent proof that 1MWh of electricity was generated by an eligible renewable energy resource. REC’s represent the environmental attributes of the renewable power, not the commodity electricity. REC’s are bought and sold on the open market. For example, some customers buy REC’s to meet their requirements for “providing” 100% of its power needs from renewables.

Resistance – (R, ohms) is a measure of the degree to which an object opposes an electric current through it. Increased resistance results in a decrease in the amount of current that will flow through the wire. Appliances, lights, power tools can all be thought as resistors. R = V/I.

RFP – Request for Proposal

RMR – Reliability Must Run – When an ISO (i.e. PJM) requires a plant to keep running when they have decided to shut down. ISO will then charge the suppliers and then it can be passed on to consumers.

ROI – Return on Investment

RPM – Reliability Pricing Model

RPS – Renewable Portfolio Standard. Regulations that mandate that a certain portion of an electric utility’s generation capacity must come from eligible renewable energy resources. Primarily state-based, and primarily targeted at IOU’s.

RTO – Regional Transmission Organization

RTP – Real-time pricing

S (Top)

SEER – Seasonal Energy Efficiency Ratio

Slamming – The unauthorized transfer of a customer’s electric service by a retail electric provider.

SIC – Standard Industrial Classification

SUB – Substation

T (Top)

TCUL – Tap Changing Under Load

Therm – used to measure natural gas usage equal to 100,000 Btu. 10 therms = 1MMBtu.

TOU – Time-Of-Use

TPS – Third Party Supplier

Transmission system – An interconnected group of lines and equipment for the movement or transfer of bulk electric energy between points of supply and points at which it is transformed for delivery to customers or is delivered to other electric systems. Typically 69,000 volts (kV) and higher.

TRM – Transmission Reserve Margin or Transmission Reliability Margin

U (Top)

UCAP – Uninstalled Capacity

Unbundling – The separation of traditional electric utilities into three companies-retail, wires and generation-by either separating into affiliated companies owned by a common holding company, separating into nonaffiliated companies or selling assets to a third party. Unbundled utilities are governed by code of conduct rules to ensure a fair and competitive market.

V (Top)

VAR – Volt Ampere Reactive

Voltage – (Volts) (V) Difference of electrical potential across two points, or electromotive force behind the flow of electricity. This is the amount of potential energy in a circuit. Like the pressure in a pipe from a pump or the height of a waterfall. Sources of voltage include batteries, photovoltaic cells, and generators.

W (Top)

W – Watt

X (Top)

Y (Top)

Z (Top)

*Some of these definitions are courtesy of U.S. Department of Energy, Wikipedia and PJM

Recent Posts

FERC’s ‘Demand Response’ Rule Upheld by U.S. Supreme Court – Bloomberg

Today the Supreme Court ruled in favor of Demand Response programs. From Bloomberg:

FERC’s ‘Demand Response’ Rule Upheld by U.S. Supreme Court
Greg Stohr
January 25, 2016 — 10:03 AM EST Updated on January 25, 2016 — 10:14 AM EST

The U.S. Supreme Court dealt a blow to power generators, upholding a federal rule aimed at encouraging industrial consumers to cut electricity use.
The justices, voting 6-2, said the Federal Energy Regulatory Commission acted within its authority with the order, which sets rates for an energy-saving practice known as “demand response.” The court also upheld the formula used by FERC.
The ruling is a missed opportunity for the country’s biggest energy generators, which were seeking a chance to widen their profits. A decision invalidating the rule would have benefited NRG Energy Inc., FirstEnergy Corp., Exelon Corp., Dynegy Inc., Talen Energy Corp., Calpine Corp., Public Service Enterprise Group and American Electric Power Co.
Major energy consumers, including aluminum producer Alcoa Inc., backed the rule, as did smart-grid companies such as EnerNOC Inc., which help large consumers reduce their power use.
The case centered on the U.S. Federal Power Act, which lets FERC regulate rates only at the wholesale level and leaves retail regulation in the hands of the states.
Justice Elena Kagan wrote the court’s majority opinion. Justices Antonin Scalia and Clarence Thomas dissented. Justice Samuel Alito didn’t take part in the case because of a stock holding.


  1. Energy savings brought to light Leave a reply
  2. Shutdown of two FirstEnergy power plants may be delayed Leave a reply