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Ancillary services

A collection of secondary services offered to help ensure the reliability and availability of energy to consumers. These services generally include, frequency control, spinning reserves and operating reserves. e



A unit of measurement most commonly used for crude oil. A barrel of crude oil is equal to approximately 42 US gallons or 159 litres (Note: The actual measurement depends on the fluid being measured).


The minimum amount of electric power delivered or required over a given period of time at a steady rate.

Baseload capacity

The generating equipment normally operated to serve loads on an around-the-clock basis.

Baseload supply

The actual available power used to meet minimum expected customer requirements at a given time (baseload demand).

Basis point

One hundredth of a percent, or one ten thousandth of the total, usually used as a unit of measurement relative to another measurement, normally a measurement whose value changes over time.


The abbreviation for barrel.


A blackout is a complete interruption of power in a given service area.


(Gas) Mixing gases of different specifications to produce one within the required gas specification. (Crude) Sometimes crudes areblended near source when the same storage terminal or pipeline is used. An example is Brent Blend – a blend of crudes from various fields in the East Shetland Basin. Also used to create components for gasoline.

British Thermal Unit (BTU), MBTU, MMBTU

A standard unit of measurement used to denote both the amount of heat energy in fuels and the ability of appliances and air conditioning systems to produce heating or cooling. A BTU is the amount of heat required to increase the temperature of a pint of water (which weighs exactly 16 ounces) by one degree Fahrenheit. Since BTUs are measurements of energy consumption, they can be converted directly to kilowatt-hours (3412 BTUs = 1 kWh) or joules (1 BTU = 1,055.06 joules). MBTU stands for one million BTUs, which can also be expressed as one decatherm (10 therms). MBTU is occasionally used as a standard unit of measurement for natural gas and provides a convenient basis for comparing the energy content of various grades of natural gas and other fuels. One cubic foot of natural gas produces approximately 1,000 BTUs, so 1,000 cu.ft. of gas is comparable to 1 MBTU. MBTU is occasionally expressed as MMBTU, which is intended to represent a thousand thousand BTUs.


An agent or facilitator in a deregulated energy market who acts as an intermediary between energy producers and energy consumers.

Bundled service

Energy provisions in which all needed services are provided as a single package, usually by a single provider who provides a single invoice. While energy provision might appear to be a single service, it actually consists of numerous specific services, which are all required before an end-use customer can receive energy. These services include generation of energy, transmission of electricity, distribution from the transmission system, metering and billing, and support functions required to maintain consistent supply.



Compañía Administradora del Mercado Eléctrico Mayorista S.A., the entity responsible for programming and dispatching the MEM power generation in accordance with Secretariat of Electric Energy's Resolution No. 61/92 as amended and supplemented.


The maximum amount of power, normally expressed in megawatts, that a given system or subsystem can carry or produce at a particular moment, and is typically usedto represent the real production capability rating of a generation or transmission system.

Capacity factor, plant factor

The value used to express the average percentage of full capacity used over a given period of time.
Capacity Factor: Can apply to an individual generating unit or any collection of generating units.
Plant factor: Refers to the capacity factor of an entire generating facility including all available generating units.

Capital costs

Include costs for land, taxes, surveying, construction, inspection, materials, labour, and interest on loans or bonds.

Central power

Central power is the opposite of distributed power. The generation of electricity in large power plants with distribution through a network of transmission lines for sale to a number of users.

Certified Emission Reduction (CER)

CERs are generated by Clean Development Mechanism (CDM) Projects. One CER corresponds to a carbon credit of one tonne CO2 equivalent.

City Gate

Means the location at which there is a change in gas ownership or transportation responsibility from a pipeline to a local distribution company or gas utility.

Cogeneration (cogen)

The simultaneous generation of electrical and thermal energy where both forms of energy are put to productive use. The addition of cogeneration capability to generating facilities and industries that produce large amounts of heat energy helps ensure that waste heat (usually in the form of steam or hot water) is used efficiently for heating, industrial use, agriculture or conversion into electricity.

Combined cycle

An electric generating technology in which electricity is produced from otherwise lost waste heat exiting from one or more gas (combustion) turbines. The exiting heat is routed to a conventional boiler or to a heat recovery steam generator for utilization by a steam turbine in the production of electricity. This process increases the efficiency of the electric generating unit.

Combined cycle power plants (CC or CCGT)

Twin-stage power plants that deliver 50-60% higher fuel efficiency. In the first stage, a gas (natural gas, gaseous coal, etc.) is heated, cleaned, and used to run a gas turbine that produces electricity. In the second stage, the waste heat from the gas turbine, from gas cleaning, and from the gasification processes are used to raise the pressure of steam, which is in turn used for generation of additional power. By operating a combination of both these stages, a combined cycle power plant is able to maximize the efficiency of the fuel used.

Commercial operation

Commercial operation begins when control of the loading of the generator is turned over to the system dispatcher.


Commercial operation date.


Clogging and stress at a point where something must pass. Congestion in energy transmission systems occurs when local demand for energy approaches the limits of the transmission system’s ability to supply it.

Consumer Price Index (CPI)

An economic measure calculated as the average change in prices for a fixed group (basket) of products and services considered to be either essential or universally desirable for a given population or segment of the population.

Contract terms

The specific details or the sum total of all details that make up an agreement between buyer and seller.

Crude oil

A full-ranging hydrocarbon mixture produced from a reservoir after any associated gas has been removed. Among the most commonly traded crudes are the North Sea’s Brent Blend, the US’s West Texas Intermediate (WTI) and Dubai.


Costo Marginal Operado (Operated marginal cost)



The process of removing a power plant, apparatus, equipment, building, or facility from operation.

Delivery point

A point on the grid where one electric utility can transfer its available energy to another utility’s system.


The production of energy by a system or appliance at a level less than its design or nominal capacity.


The relaxation, reduction or complete removal of legislated restrictions from an industry or industry sector whose activities were previously under strict government supervision.


To control flow and direction. Energy dispatch controls how much energy travels through specific transmission stations to end-use service areas. Energy dispatch requires a human operator to schedule, monitor and control distribution of energy. The process of coordinating the distribution of energy on a moment-to-moment basis to meet changing load requirements.

Distribution system

The combination of the physical hardware required to deliver energy between high-voltage transmission lines and end-use customers, and the procedures and processes used to perform the actual delivery. The term can also refer to a company or utility that performs distribution services.


Activities in the oil and gas industry from a refinery onwards – ie, the distribution and marketing of hydrocarbon products.


Economic dispatch

A method of managing the operation (dispatching) of generation and transmission facilities to produce the most cost-effective result. Economic dispatch most commonly involves the selection of the lowest-cost available generating units or fuels for powering available units.

Electricity generation, gross

The total amount of electric energy produced by the generating station or stations, measured at the generator terminals.

Electricity generation, net

Gross generation less electricity consumed at the generating plant for station use. Electricity required for pumping at pumped-storage plants is regarded as plant use and is deducted from gross generation.


Substance(s) or pollutant emitted as a result of a process.

ENRE (Ente Nacional Regulador de la Electricidad)

The National Electricity Regulatory Body in the Argentine Republic.

End-use customer

A customer who acquires energy for their own consumption. Customers who acquire energy for provision to other customers are not the actual users of the energy, and are not considered end-use customers



An existing or planned location or site at which prime movers, electric generators, and/or equipment for converting mechanical, chemical, and/or nuclear energy into electric energy are situated, or will be situated. A facility may contain more than one generator of either the same or different prime mover type. For a cogenerator, the facility includes the industrial or commercial process.

Fixed cost

A production- or transmission-related expense that must be paid regardless of whether the energy is produced or sold. Fixed costs can include capital costs, labour and maintenance charges, taxes and demand charges among others.

Fixed price

A price that cannot or will not be changed.

Flat rate

An electricity rate with one single component price that includes charges for all services related to energy provision. A flat rate for each kilowatt-hour of energy consumed, not a fixed price for an unlimited quantity of energy.

Fuel oil (FO)

Heavy refined distillates. Used to fuel power stations and in ships and industry. The different fuel oil grades are classified according to their viscosity and sulphur content.


Fondo de Inversiones del Mercado Eléctrico Mayorista


Gas nominations

Nomination deadlines are where each pipeline has a scheduled deadline before which shippers must book gas for the following period.

Generation company (GENCO)

A regulated or non-regulated company engaged solely in producing electricity. A company that generates energy.

Geothermal energy

Heat (thermal) energy stored in rock below the Earth’s surface.

Gigawatt (GW)

One billion watts.

Gigawatthour (GWh)

One billion watthours.


Major Large Users (“GUMA”, in Spanish) with a demand of 1 MW or more.


Minor Large Users (“GUME”, in Spanish), with a demand of between 30 KW and 2 MW.


Private Large Users (“GUPA”, in Spanish), with a demand of between 30 kW and 100 Kw.


Large users with a demand above 300 kW, buy energy at a regulated price through a distributor.

Green power

Any type of energy that is considered to have a lower environmental impact than commercially-produced energy.


The layout of an electrical distribution system.


Heat rate

A measurement used in the energy industry to calculate how efficiently a generator uses heat energy. It is expressed as the number of BTUs of heat required to produce a kilowatt-hour of energy. Operators of generating facilities can make reasonably accurate estimates of the amount of heat energy of a given quantity of any type of fuel, so when this is compared to the actual energy produced by the generator, the resulting figure tells how efficiently the generator converts that fuel into electrical energy.

Heavy oil

The fuel oils remaining after the lighter oils have been distilled off during the refining process. Except for start-up and flame stabilization, virtually all petroleum used in steam plants is heavy oil.

Henry Hub (HH)

The delivery point for the largest NYMEX natural gas contract by volume. Henry Hub is in Erath, Louisiana, and is a large system of pipeline interconnects.


Independent power producer (IPP), non-utility generator (NUG)

A producer of electrical energy which is not a public utility but which makes electric energy available for sale to utilities or the general public.

Independent system operator (ISO)

Entity responsible for ensuring the efficient use and reliable operation of the transmission grid and, in some cases, generation facilities.

Interruptible energy

Flow that can be reduced or completely stopped with little or no notice.


Kilowatt (kW)

One thousand watts.

Kilowatt demand

A measure of average load over a given period expressed in kilowatts. This measurement is used by utilities and wholesalers to determine a customer’s average requirement.


A quantitative measure of electric current flow equivalent to one thousand watts being used continuously for a period on one hour; the unit most commonly used to measure electrical energy, as opposed to kilowatt, which is simply a measure of available power.

Kyoto Protocol

The Kyoto Protocol was agreed by all countries under the UN Framework Convention on Climate Change in Kyoto, Japan, in December 1997. The Protocol requires industrialised countries to meet differentiated greenhouse gas emissions reduction targets relative to 1990 levels during the period 2008-12. It has been ratified by 177 countries, including all industrialised countries, with the exception of the United States of America. The Protocol establishes the framework for international emissions trading as well as the Clean Development Mechanism which aims to incentivise clean investment in developing countries.


Light oil

Lighter fuel oils distilled off during the refining process. Virtually all petroleum used in internal combustion and gas turbine engines is light oil.

Liquefied natural gas (LNG)

Natural gas (mainly methane) that has been liquefied for ease of storage and transportation. The gas is liquefied either by reducing the temperature or by increasing pressure.

Liquefied petroleum gas (LPG)

A light hydrocarbon composed mainly of propane and butane, occurring naturally in crude or from refining processes such as crude distillation, catalytic reforming or hydro-cracking. Gaseous at atmospheric pressure and temperature, LPGs are liquefied by reducing temperature or increasing pressure for ease of transportation and storage.

Load factor

A measure of the average load, in kilowatts, supplied during a given period. It is used to determine the total amount of energy that would have been used if a given customer’s maximum load was sustained over an extended period of time. This value offers a useful comparison to show what percentage of a customer’s potential usage is actually used. Load factor is a fairly complex calculation that is derived this way: (kWH of energy used x 100) / (maximum kilowatt demand x hours in the measured period).


MEM (Mercado Eléctrico Mayorista)

The Argentine Wholesale Electricity Market.


One thousand cubic feet.

Megawatt (MW)

One million watts.

Megawatthour (MWh)

One million watt-hours.


Ministry of Federal Planning, Public Investment and Services


One million British thermal units, one dekatherm. Approximately equal to a thousand cubic feet (Mcf) of natural gas.


One million cubic feet.



The notification to put into effect a contract or part of a contract, eg, a gas flow nomination from a shipper to advise the pipeline owner of the amount of gas it wishes to transport or hold in storage on a given day.

Non-firm power

Power or power-producing capacity supplied or available under a commitment having limited or no assured availability.



Operation and maintenance

On peak

Refers to hours of the business day when demand is at its peak.

Organisation of the Petroleum Exporting Countries (OPEC)

OPEC members are Algeria, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, Venezuela, and UAE. OPEC member states have two regular meetings a year, but may call further meetings if crude oil prices are low. At these meetings they may review both individual and group production quotas. Although not the dominant force it was in the late 1970s, because of the increase in production by non-OPEC countries, OPEC continues to control marginal supply in a world oversupplied with crude oil.

Open access

When an energy customer can use one party’s transmission systems to receive energy from another party, that customer is said to have open access to the transmission system. Prevents a utility that owns or controls a region’s transmission and distribution systems from also controlling the energy supply. Differs from direct access in that direct access refers to acquisition of actual energy, whereas open access refers only to access to transmission systems used to transport it.

Operating reserve

Reserve of power (spinning and nonspinning) to be available at all times to ensure reliable grid operation. A grid’s operating reserve consists of all reserves available to serve customers connected to that grid.

Opt out

The right of individual retail customers to choose not to acquire energy from an aggregator, co-op or utility that is able to serve them. Customers can only opt out if another party is ready and able to provide them with energy.


Any interruption of current flow in a transmission or distribution system. Can occur in transmission systems without affecting end-use customers. Energy grids are designed to allow energy to be routed around areas affected by outages to ensure uninterrupted service to end-use customers.


Peak demand

The maximum load during a specified period of time.

Peak load plant

A plant usually housing old, low-efficiency steam units, gas turbines, diesels, or pumped storage hydroelectric equipment normally used during the peak-load periods.

Peak load, peak demand

The maximum power requirement of a system at a given time, or the amount of power required to supply customers at times when need is greatest. They can refer either to the load at a given moment (eg, a specific time of day) or to averaged load over a given period of time (eg, a specific day or hour of the day).

Peak shaving

During times of peak demand, supplies from sources other than normal suppliers are used to reduce demand on the system.



Power factor, loss factor, standby loss factor

One volt at one ampere is usually calculated as one watt of power.
Power Factor: The ratio between actual work done and the potential to perform real work, usually expressed as a percentage of total current throughput.
Loss factor: An expression of the average power factor over a given period of time, and is used in the energy industry to express the losses in transmission and distribution from heat, incomplete combustion of fuels and other inefficiencies.
Standby Loss Factor: A ratio between actual and potential energy consumed, but it refers to the loss of energy that results from keeping a device on standby service without actually using it.

Power Purchase Agreement (PPA)

PPA refers to a contract entered into by an independent power producer and an electric utility. The power purchase agreement specifies the terms and conditions under which electric power will be generated and purchased. Power purchase agreements require the independent power producer to supply power at a specified price for the life of the agreement.

Power plant

Most commonly, a generating station or energy production facility. A site, structure or location where electricity is produced.


Refined products

The products derived from crude oil that have been processed in a refinery.


A plant where crude oil is separated into various components such as usable products or feedstocks.


The process of increasing or decreasing capacity in the system in response to changes in customer requirements. This type of regulation usually occurs at generating facilities, although the capacity of transmission and distribution systems can also be regulated.
The actual amount of generating capacity that can be added to or removed from the system by an independent system operator’s energy management system. In this context, a system’s regulation is its capacity to be adjusted (regulated) on demand.

Reserve margin, reserve capacity

A measure of available capacity over and above the capacity needed to meet normal peak demand levels. A producer’s capacity to generate more energy than the system normally requires. For a transmission company, it refers to the capacity of the transmission infrastructure to handle additional energy transport if demand levels rise beyond expected peak levels.


Payments, in money or kind, of a stated share of production from mineral deposits, by the lessee to the lessor. May be an established minimum, a sliding-scale, or a step-scale. A step-scale royalty rate increases by steps as the average production on the lease increases. A sliding-scale royalty rate is based on average production, and applies to all production from the lease.


Spinning reserve, non-spinning reserve

Spinning Reserve: Any back-up energy production capacity which is can be made available to a transmission system with 10 minutes’ notice and can operate continuously for at least two hours once it is brought online.
Non-spinning Reserve: Generating capacity that is capable of being brought online within 10 minutes if it is offline, or interrupted within 10 minutes if it is online, and which is capable of either being operated or interrupted for at least two hours.

Spot market, real-time market

The spot market is a real-time commodity market for instant sale and delivery of energy. Spot markets exist for natural gas, where they’re operated on a time scale of days to weeks. There is no single spot marketplace for energy. Spot markets can operate wherever the infrastructure exists to conduct the transactions. Most spot markets that used to be conducted on trading floors are now operated over the Internet.



The obligation to pay for a specified amount of gas whether this amount is taken or not. Depending on the contract terms, under-takes or over-takes may be taken as make-up or carry forward into the next contract period. When it is credited into another contract period, this is called make-up gas.

Therm, decatherm

A measurement of heat equivalent to 100,000 BTU. Decatherm is more widely used in the energy industry. A decatherm equals one million BTU.

The Procedures

The procedures designed for the operational schedule, the dispatch of loads and price calculation, set out in former Secretariat of Electric Energy's Resolution No. 61/92, as amended and supplemented.

Transmission charge

A charge added to a customer’s electrical bill, which is intended to cover the cost of transmitting energy over the transmission grid between the generating facility and the local utility’s distribution facilities.

Transmission company (TRANSCO), transmitting utility

An independent company that owns and/or maintains energy transmission facilities; or more correctly, a theoretical company that, if it existed, would engage in this activity.

Transmission congestion

Occurs when there is insufficient energy to meet the demands of all customers.



The separation of component parts of a previously unified product or service usually provided by a single party into distinct products or services each provided by different parties.


Oil and gas exploration and production, as opposed to downstream, which covers the areas of refining and marketing.


Any private company, publicly-owned organisation or other regulated entity that provides an essential service in a given area directly to end-use customers, and that has exclusive rights to provide that service or acts as a natural monopoly in the region it serves. Gas, water and electric companies all qualify as utilities.


Variable cost

Costs incurred from energy generation or transportation and delivery that change in proportion to the amount of energy used.
Includes costs of fuel, operating expenses, equipment and facility maintenance charges, and depreciation from wear and tear on equipment among others.



The electrical unit of power. The rate of energy transfer equivalent to 1 ampere flowing under a pressure of 1 volt at unity power factor.

West Texas Intermediate (WTI)

US crude oil used as a benchmark for pricing much of the world’s crude oil production.