Energy & Renewables Vocabulary: 100 Key English Terms
English is the working language of much of the energy sector: equipment datasheets, grid codes, feasibility studies, power purchase agreements, market reports and international climate documents are mostly written in it. Knowing the core words for power generation, the grid, solar, wind, hydro and nuclear power, storage, efficiency, energy markets and emissions policy helps you read technical documents with confidence, work with investors, suppliers and grid operators, and follow the fast-moving energy transition.
100 terms
10 topics
46 core terms
200 example sentences
Read, understand, keep going
No account needed. Read the meaning, see where the term is used, then study the examples. Click any word in the lesson for help. You can also select a word and press Alt + Enter.
Energy Basics and Units
renewable energy
noun
Meaning
Energy from sources that nature replaces all the time, such as sunlight, wind, flowing water, the Earth's heat and organic material, so they do not run out like coal, oil or gas.
Where you use it
The umbrella term in policy papers, company strategies and news. People often shorten it to renewables ('investment in renewables'). Common phrases include renewable energy sources, renewable capacity, renewable energy targets and renewable energy projects.
Examples
On sunny, windy days, renewable energy covers more than half of the country's electricity demand.
The company plans to double its renewable energy capacity by 2030.
Usage note
Renewable and clean are not exactly the same: nuclear power is low-carbon and often called clean, but it is not renewable.
Common phrases
renewable energy sources · renewable energy targets · invest in renewables · renewable capacity
A unit of energy equal to using or producing 1,000 watts of power for one hour. Household electricity bills and many energy statistics are given in kWh.
Where you use it
The everyday unit for amounts of energy. Larger amounts are given in megawatt-hours (MWh), gigawatt-hours (GWh) and terawatt-hours (TWh). Consumer prices are quoted per kWh, wholesale prices per MWh. Read it aloud as 'kilowatt-hours' or letter by letter, 'K-W-H'.
Examples
The average household here uses about 230 kilowatt-hours a month.
We pay around 15 cents per kilowatt-hour on the commercial tariff.
Usage note
Do not write kW/h or 'kW per hour'. Energy is power multiplied by time, so the correct form is kWh.
Common phrases
per kilowatt-hour · price per kWh · kilowatt-hours a year · megawatt-hours
A unit of power equal to one million watts, or 1,000 kilowatts. It is used to describe the size of power plants, wind turbines and large solar projects.
Where you use it
Megawatts describe power, the rate at which energy is produced or used, not the amount of energy. You say a 50-megawatt wind farm or a 5 MW turbine. National systems are described in gigawatts (GW). For energy over time, use megawatt-hours (MWh).
Examples
Each turbine is rated at 4.5 megawatts.
The project adds 120 megawatts of solar capacity to the region.
Usage note
Before a noun, the number and unit are joined with a hyphen and the unit stays singular: a 50-megawatt plant, not a 50-megawatts plant.
Common phrases
a 100-megawatt plant · megawatts of capacity · megawatt-hour · rated at 5 megawatts
A fuel such as coal, oil or natural gas that formed underground over millions of years from the remains of plants and animals. Burning it releases carbon dioxide.
Where you use it
Usually plural (fossil fuels) in talk about energy policy, emissions and the energy transition. Countries depend on, import, subsidise and move away from fossil fuels; fossil-fuel plants and fossil-fuel generation are common phrases.
Examples
The country still imports most of the fossil fuels it uses for power generation.
Our goal is to cut fossil fuel use in our factories by half before 2035.
Common phrases
burn fossil fuels · dependence on fossil fuels · fossil fuel subsidies · move away from fossil fuels
The combination of energy sources, such as gas, coal, hydro, wind, solar and nuclear, that a country or company uses, usually shown as percentage shares.
Where you use it
Used in reports, policy papers and news. People talk about the energy mix, power mix or generation mix, about diversifying it and about the share of renewables in it. Strictly, the energy mix covers all energy use, while the power mix covers only electricity.
Examples
Coal's share in the energy mix fell below 30 percent last year.
A diverse energy mix makes the system less exposed to gas price shocks.
Common phrases
diversify the energy mix · share in the energy mix · power mix · generation mix
The process of producing electricity, or the amount of electricity produced over a period, by power plants, solar panels, wind turbines and other sources.
Where you use it
Used for both the activity and the volume. You hear power generation, electricity generation, solar generation and generation capacity; energy companies have a generation business. The verb is generate: a plant generates electricity. Generation is measured in MWh or GWh.
Examples
Wind generation was unusually low last week, so gas plants filled the gap.
Our generation portfolio includes hydro, wind and solar assets.
Usage note
Turkish 'üretim' covers both generation and production. For electricity, generation is the usual word; production is more common for oil, gas and manufactured goods.
An industrial facility that produces electricity on a large scale, for example by burning gas or coal, splitting atoms or using the energy of water, wind or sunlight.
Where you use it
The standard general term, often combined with the fuel or technology: gas-fired power plant, coal plant, nuclear power plant, hydroelectric plant. British English also says power station. Plants are built, operated, shut down and decommissioned.
Examples
The power plant runs at full load during the summer peak.
Three old coal power plants will close by the end of the decade.
Common phrases
gas-fired power plant · nuclear power plant · build a power plant · power plant operator · shut down a power plant
The maximum power output that a power plant, or all the plants in a country, can deliver according to their design, usually given in MW or GW.
Where you use it
A key figure in reports, investor presentations and national statistics. Installed capacity grows or reaches a level, and new capacity is added. It shows the size of a fleet, not how much it actually produces; real output depends on the capacity factor.
Examples
Solar installed capacity in the country has more than tripled in five years.
Wind makes up 12 percent of installed capacity but a smaller share of actual generation.
Common phrases
total installed capacity · add installed capacity · installed capacity of 500 MW · installed solar capacity
A fossil fuel made mostly of methane, burned in power plants, industry and homes. It emits less CO2 than coal for the same electricity, but it is still a fossil fuel.
Where you use it
In energy English often just gas: gas prices, gas-fired plants, gas supply. It arrives by pipeline or by ship as liquefied natural gas (LNG). Volumes are given in cubic metres (bcm, billion cubic metres) and prices often per MWh or per MMBtu.
Examples
High natural gas prices made coal plants more competitive last winter.
The new terminal can receive natural gas as LNG from several suppliers.
Usage note
In American English gas also means petrol (benzin), so in mixed contexts say natural gas to avoid confusion.
Common phrases
natural gas prices · gas-fired power plant · natural gas supply · liquefied natural gas
The ratio of the electricity a plant actually produces over a period to what it would produce running at full capacity the whole time, shown as a percentage.
Where you use it
Used to compare technologies and judge project economics. Solar farms typically reach about 15 to 25 percent, onshore wind about 25 to 40 percent and nuclear more than 80 percent. A plant achieves or runs at a given capacity factor.
Examples
The site's strong winds give it a capacity factor of nearly 40 percent.
A 10 MW plant with a 20 percent capacity factor produces about 17,500 MWh a year.
Usage note
Do not confuse capacity factor with efficiency. A solar panel can be 22 percent efficient and have a 20 percent capacity factor; the two numbers measure different things.
Common phrases
high capacity factor · annual capacity factor · capacity factor of 35 percent · improve the capacity factor
The minimum level of electricity demand that continues day and night, and the power plants that run almost all the time to supply it.
Where you use it
Often used like an adjective: baseload plants, baseload power, baseload generation. Nuclear, coal, lignite and some hydro and geothermal plants have traditionally supplied baseload. With more solar and wind, many experts now prefer to talk about flexibility instead. Also written base load.
Examples
Lignite plants still supply much of the country's baseload.
Geothermal is one of the few renewables that can run as baseload.
Common phrases
baseload power · baseload plant · provide baseload · baseload generation
An engine that burns gas, usually natural gas, and uses the hot expanding gases to spin a turbine connected to a generator. It can start and change output quickly.
Where you use it
Used alone in open-cycle peaking plants (OCGT) or with a steam turbine in combined cycle plants. Gas turbines are started, loaded and sometimes tripped; inspections are planned by operating hours. Some models can burn hydrogen blends.
Examples
The open-cycle gas turbine can reach full load in about ten minutes.
We scheduled the gas turbine overhaul for the low-demand season.
Common phrases
open-cycle gas turbine · gas turbine overhaul · start the gas turbine · hydrogen-ready gas turbine
A machine in which high-pressure steam flows over rows of blades and turns a shaft connected to a generator. Coal, nuclear, geothermal and many biomass plants use one.
Where you use it
The steam comes from a boiler, a reactor or a heat recovery steam generator (HRSG). After the turbine, the steam is cooled back into water in a condenser. Engineers talk about steam pressure and temperature, turbine efficiency and turbine trips.
Examples
In a combined cycle plant, the steam turbine produces about a third of the total output without burning extra fuel.
The steam turbine tripped after a vibration alarm.
A plant design in which a gas turbine generates electricity and its hot exhaust makes steam for a steam turbine, which generates more electricity from the same fuel.
Where you use it
Usually seen as combined cycle gas turbine (CCGT) or combined cycle power plant. Modern CCGT plants reach efficiencies of around 60 percent, compared with roughly 35 to 40 percent for open-cycle gas turbines. Before a noun it is often hyphenated: a combined-cycle plant.
Examples
The new combined cycle plant uses 30 percent less gas per MWh than the old units.
In the evening, combined cycle units often set the market price.
Common phrases
combined cycle gas turbine · combined cycle power plant · CCGT efficiency · combined-cycle unit
Producing electricity and useful heat at the same time from one fuel, so that heat a normal power plant would waste is used in buildings or industry.
Where you use it
Shortened to CHP and also called cogeneration. CHP plants are common in factories, hospitals, district heating systems and greenhouses. Overall efficiency can exceed 80 percent. When cooling is added, it is called trigeneration.
Examples
The hospital's combined heat and power unit supplies electricity, hot water and steam.
A combined heat and power plant makes sense when the site needs heat all year round.
Common phrases
CHP plant · combined heat and power unit · cogeneration · district heating · trigeneration
Describing a power plant or boiler that burns coal to produce heat and electricity. Coal-fired plants are among the largest sources of carbon emissions.
Where you use it
Common in news and policy: coal-fired power plant, coal-fired generation, coal-fired capacity. The same pattern works for other fuels: gas-fired, oil-fired, lignite-fired. Many countries plan to close such plants or convert them to other fuels.
Examples
The utility will close its last coal-fired plant in 2032.
Coal-fired generation rose when gas prices spiked.
Usage note
In this compound, fired means 'fuelled'. Before a noun it takes a hyphen: a coal-fired plant.
To close a power plant or other facility permanently, take it out of service and, in many cases, dismantle it and restore the site.
Where you use it
Used for coal plants, nuclear reactors, wind turbines and oil platforms. Plants are decommissioned at the end of their life. The noun is decommissioning: decommissioning costs, a decommissioning plan. Decommissioning a nuclear plant can take decades.
Examples
The utility will decommission two coal units next year.
The budget includes decommissioning the old wind turbines and recycling the blades.
Common phrases
decommission a plant · decommissioning costs · decommissioning plan · nuclear decommissioning
Describing a power source whose output can be started, raised or lowered on request, such as gas, reservoir hydro or batteries, unlike weather-dependent solar and wind.
Where you use it
Used in system planning and market design: dispatchable generation, dispatchable capacity. The verb dispatch means to instruct a plant to run at a certain level; grid operators usually dispatch plants in merit order, cheapest first.
Examples
As coal plants close, we need new dispatchable capacity for windless winter evenings.
Batteries and reservoir hydro are both dispatchable, but only for a limited time or volume.
Common phrases
dispatchable generation · dispatchable capacity · dispatch a plant · merit order
To increase the output of a power plant, or the level of an activity, steadily over a short time. The opposite is ramp down.
Where you use it
Used in plant operation and in general business English (ramp up production, ramp up hiring). Engineers talk about the ramp rate, in MW per minute, which shows how fast a plant can change output. Gas turbines and batteries ramp quickly; coal and nuclear plants ramp slowly.
Examples
Gas plants ramp up quickly as solar output falls in the evening.
We can ramp the unit up from 200 to 400 MW in about 20 minutes.
Common phrases
ramp up output · ramp down · ramp rate · ramp up production
The stage at the end of construction when a new plant or system is tested, checked against its specifications and handed over for normal operation.
Where you use it
A key project phase with its own team and documents. Plants go through cold and hot commissioning and performance tests before the commercial operation date (COD). The verb is commission: the wind farm was commissioned in May. People also say the plant came online.
Examples
Commissioning of the battery system took three weeks longer than planned.
The commissioning engineer signs off each test before the plant reaches COD.
Common phrases
commissioning phase · commissioning tests · commercial operation date · come online · commission a plant
The network of power lines, substations and transformers that carries electricity from where it is produced to homes, businesses and factories.
Where you use it
Used constantly by engineers, regulators and journalists. Power is fed into the grid or drawn from the grid, and plants are connected to the grid. Common phrases: national grid, grid stability, grid capacity, grid code and on-grid or off-grid.
Examples
The solar plant will feed about 40 GWh a year into the grid.
The grid in this region is already congested, so new projects face long waiting times.
Usage note
In the UK, National Grid is also the name of a company, so it often appears with capital letters.
Common phrases
feed into the grid · connect to the grid · grid stability · grid capacity · national grid
A high-voltage power line, usually on tall steel towers, that carries large amounts of electricity over long distances from power plants to substations.
Where you use it
Used by grid planners, engineers and developers. Lines are built, upgraded, energised, maintained and sometimes overloaded. Overhead lines are the norm; underground and submarine cables are used where needed. Voltages are given in kV, for example a 380 kV line.
Examples
A new 380 kV transmission line will carry wind power from the coast to the industrial zone.
The storm brought down two transmission line towers.
Usage note
Transmission is long-distance, high-voltage transport; distribution is the lower-voltage network that delivers power to consumers. Do not use them as synonyms.
Common phrases
high-voltage transmission line · overhead transmission line · build a transmission line · transmission line tower
A site with transformers, switches and protection equipment where voltage is raised or lowered and power flows are switched between lines.
Where you use it
Part of every grid connection discussion. A project connects to a substation; substations are built, expanded and energised. Step-up substations at power plants raise the voltage; step-down substations near cities lower it.
Examples
The wind farm connects to the grid at a 154 kV substation 12 km away.
The outage started with a fault in the substation transformer.
Common phrases
step-up substation · step-down substation · connect to a substation · substation transformer · build a substation
The amount of electrical power that consumers or a device draw from the system at a given moment, or the equipment that uses that power.
Where you use it
Used constantly in grid and plant operation. System load rises in the evening; a plant runs at full load or part load. Engineers talk about the load profile, load curve and load forecast.
Examples
System load peaked at 55 GW during the heatwave.
The gas plant has been running at part load since the morning.
Usage note
In grid talk, load and demand are often used in the same sense; load can also mean the device itself, as in 'disconnect the load'.
Common phrases
full load · part load · load profile · load forecast · system load
The highest level of electricity demand in a given period, such as a day or a year, which the power system must be able to supply.
Where you use it
Central to grid planning and tariffs. Peak demand rises, hits a record and is met, reduced or shifted. Peak hours are when prices are usually highest; off-peak hours are the cheaper rest of the day.
Examples
Air conditioning pushes peak demand to a new record almost every July.
The batteries help us cut the charges we pay for our peak demand.
A period when electricity is not available to customers because of a fault, bad weather, damage to the network or planned maintenance.
Where you use it
Common in customer messages, news and reliability reports. An outage happens, affects customers and lasts hours until power is restored. Planned outages are announced in advance; unplanned outages are not. British English often says power cut.
Examples
The power outage affected about 20,000 customers for three hours.
There will be a planned power outage on Sunday for transformer maintenance.
Usage note
For power plants, outage also means a period when a unit is offline, as in 'a planned maintenance outage'.
Common phrases
planned outage · unplanned outage · power is restored · outage affects customers · power cut
The lower-voltage part of the power system that takes electricity from substations and delivers it through local lines and cables to homes and businesses.
Where you use it
Run by a distribution system operator (DSO), also called a distribution company. Engineers talk about medium-voltage and low-voltage networks, network reinforcement and connecting rooftop solar. American English often says distribution grid or distribution system.
Examples
Too many rooftop systems on one street can overload the local distribution network.
The DSO will reinforce the distribution network in the old town next year.
Common phrases
distribution network operator · low-voltage network · medium-voltage network · reinforce the distribution network
A device that raises or lowers the voltage of alternating current. Transformers make long-distance transmission possible and bring the voltage down to safe levels for users.
Where you use it
Found everywhere in the grid: power transformers in substations, distribution transformers on poles or in kiosks, step-up transformers at power plants. They are rated in kVA or MVA and can overheat, fail or be overloaded. Long delivery times for large units often delay projects.
Examples
The step-up transformer raises the voltage from 33 kV to 154 kV.
Delivery of the main transformer is now expected in March.
Common phrases
step-up transformer · power transformer · distribution transformer · transformer rating · transformer failure
A total loss of electricity over a large area, often caused when a major fault spreads through the grid faster than operators can contain it.
Where you use it
Used for large, serious events, often in the news. A blackout hits a region, spreads and lasts hours until power is restored. Grid operators keep black start plans to restart the system without outside power. Smaller local interruptions are usually called outages.
Examples
The blackout left millions of people without power for most of the day.
The investigation found that a single line fault triggered the blackout.
Usage note
Rolling blackouts are planned cuts that move from area to area to protect the grid; they are a form of load shedding, not an uncontrolled failure.
Common phrases
nationwide blackout · cause a blackout · prevent blackouts · black start · rolling blackouts
The way the output of solar and wind changes with the weather and the time of day, so it cannot be fully controlled or guaranteed at every moment.
Where you use it
A common topic in grid planning and in debates about renewables. People speak of intermittent renewables and variable renewable energy (VRE), managed with storage, flexible plants, interconnections and demand response. Many engineers prefer the word variability.
Examples
Battery storage helps us manage the intermittency of solar output.
Critics of wind power often focus on intermittency, but forecasting has improved a lot.
The physical link and the formal permission that allow a power plant, storage system or large consumer to send electricity to, or take it from, the grid.
Where you use it
Often the biggest hurdle in project development. Developers apply for, secure, wait for and pay for a grid connection. Key phrases: grid connection agreement, connection point, connection capacity and connection queue (the waiting list of projects).
Examples
We have the land and the permits; the only thing missing is a grid connection.
In some regions, the wait for a grid connection is now more than five years.
Common phrases
secure a grid connection · grid connection agreement · connection point · connection queue · apply for a grid connection
The number of times per second that alternating current changes direction, measured in hertz (Hz). It is 50 Hz in Europe and Turkey and 60 Hz in North America.
Where you use it
Grid operators watch frequency second by second. When demand exceeds supply, frequency drops; when supply exceeds demand, it rises. Plants and batteries provide frequency response to keep it stable. Too large a deviation can lead to load shedding or a blackout.
Examples
Grid frequency fell to 49.8 Hz when the large unit tripped.
The battery earns most of its revenue from frequency response services.
Common phrases
grid frequency · frequency response · frequency control · frequency drop · frequency deviation
A voltage level used to move electricity efficiently over long distances, such as 154 kV or 380 kV. The exact limits of low, medium and high voltage differ between standards.
Where you use it
Common in grid planning, substations and safety. Abbreviated HV; related levels are low voltage (LV), medium voltage (MV) and extra-high voltage (EHV). Before a noun it is hyphenated: a high-voltage line. Warning signs say 'Danger: High Voltage'.
Examples
Only authorised staff may enter the high voltage area of the substation.
Power is stepped up to high voltage to reduce losses on long lines.
Common phrases
high-voltage line · high-voltage substation · medium voltage · low voltage · extra-high voltage
The organisation that runs the power system in real time, balancing supply and demand and keeping voltage and frequency stable across the network.
Where you use it
In Europe the transmission grid is run by a transmission system operator (TSO) and local networks by distribution system operators (DSOs); in the US, ISOs and RTOs play a similar role. The grid operator dispatches plants, issues instructions, approves connections and publishes system data.
Examples
The grid operator asked wind farms to reduce output because of a line fault.
According to the grid operator, demand will peak at 6 p.m. today.
Common phrases
transmission system operator · distribution system operator · grid operator instructions · system operator
Reducing the output of a power plant, usually wind or solar, below what it could produce, because the grid cannot take the power or there is too much supply.
Where you use it
A growing issue in markets with many renewables. Plants are curtailed by the grid operator; owners track curtailment losses and ask whether they will be compensated. Causes include grid congestion, low demand and negative prices.
Examples
Curtailment cost the wind farm about 6 percent of its annual output.
During the holiday, curtailment of solar plants in the south lasted several hours.
The part of the electricity that is lost as heat while it travels through power lines and transformers, so less reaches customers than leaves the power plant.
Where you use it
Expressed as a percentage of the energy carried. Losses are reduced by higher voltages, better conductors and efficient transformers. Reports often combine transmission and distribution losses as T&D losses or network losses.
Examples
Transmission losses on the national grid are around 2 to 3 percent.
Building solar plants near cities helps reduce transmission losses.
Usage note
The Turkish term 'kayıp-kaçak' covers both technical losses and illegal use such as theft. In English, theft and metering errors are called non-technical losses.
A power network that uses digital sensors, communication and automation to monitor and control electricity flows, making the grid more efficient and flexible.
Where you use it
Used in strategy documents, research and utility projects. Smart grid technologies include smart meters, automated switches, remote monitoring and systems that coordinate rooftop solar, batteries and electric vehicles. Projects aim to modernise, digitalise and automate the grid.
Examples
The smart grid pilot lets the utility locate faults within minutes.
Electric vehicle charging will be easier to manage on a smart grid.
Not connected to the main electricity network, so that power comes from local sources such as solar panels, batteries or a diesel generator.
Where you use it
Used for homes, farms, telecom towers, mountain huts and remote villages: off-grid solar, an off-grid system, living off-grid. The opposite is grid-connected or on-grid. Off-grid systems need batteries or backup, because there is no grid to fall back on.
Examples
The mountain station is off-grid and runs on solar panels and a small battery.
Off-grid solar kits have brought electricity to many remote villages.
Common phrases
off-grid solar · off-grid system · live off-grid · grid-connected · on-grid
A small local power network, for example on a campus, island or industrial site, with its own generation and storage, that can run connected to the main grid or on its own.
Where you use it
Used in resilience, island and campus projects. During a grid outage a microgrid can island (disconnect and keep running) and reconnect afterwards. Typical parts are solar panels, batteries, generators and a microgrid controller.
Examples
The hospital's microgrid kept the lights on during the storm.
On the island, a microgrid of solar, wind and batteries replaced most diesel generation.
Common phrases
microgrid controller · island mode · campus microgrid · build a microgrid
Deliberately cutting power to some areas or customers for a period, usually in rotation, to protect the grid when supply cannot meet demand.
Where you use it
A last-resort measure used by grid operators. Load shedding is announced in schedules, carried out and later lifted. Automatic under-frequency load shedding disconnects loads within seconds when frequency drops sharply. Some countries call it rolling blackouts.
Examples
The utility introduced two hours of load shedding each evening during the gas shortage.
Automatic load shedding stopped the frequency drop and prevented a blackout.
Usage note
In the Turkish balancing market, 'yük atma' (a YAT instruction) also means telling a power plant to reduce its output, which is not the same as load shedding.
A flat, framed unit made of many solar cells that turns sunlight directly into electricity. Many panels connected together form a solar array.
Where you use it
The everyday word; datasheets and technical documents more often say PV module or solar module. Panels are installed, mounted on roofs or frames, cleaned and inspected. Their power is given in watts peak (Wp), for example a 550 W panel.
Examples
The installers mounted 2,000 solar panels on the warehouse roof in two weeks.
Dust on the solar panels can cut output noticeably, so we clean them every month.
Usage note
A solar panel (PV) makes electricity; a solar collector or solar water heater only heats water. The two are often confused.
Common phrases
install solar panels · rooftop solar panels · clean the solar panels · solar panel efficiency · panel array
Describing technology that converts sunlight directly into electricity using semiconductor materials, as in solar cells and solar panels. It is usually shortened to PV.
Where you use it
In professional talk almost always shortened: PV module, PV plant, PV system, solar PV. It separates electricity-producing solar from solar thermal systems that produce heat. PV is read 'pee-vee'.
Examples
The photovoltaic system on the school roof covers most of its daytime electricity use.
Photovoltaic module prices fell sharply over the last decade.
Common phrases
photovoltaic system · PV module · PV plant · solar PV · photovoltaic cell
A device that converts the direct current (DC) produced by solar panels or batteries into alternating current (AC) that buildings can use or that can be fed into the grid.
Where you use it
A key part of every PV and battery project. Types include string inverters, central inverters and microinverters. Engineers discuss inverter capacity, efficiency, failures and the DC/AC ratio. Modern inverters also support the grid by controlling voltage and reactive power.
Examples
Two inverters tripped this morning, so the plant lost about 10 percent of its output.
We use string inverters on rooftops and central inverters on large ground-mounted plants.
Common phrases
string inverter · central inverter · inverter efficiency · inverter failure · DC/AC ratio
A large ground-mounted installation of solar panels, usually covering many hectares, that produces electricity to sell to the grid rather than to power a single building.
Where you use it
Also called a solar park, solar plant or utility-scale solar. Developers find land, secure a grid connection, then build and operate the solar farm. Technical documents often say ground-mounted PV plant.
Examples
The 80 MW solar farm will cover about 150 hectares of former farmland.
Sheep graze under the panels at our solar farm to keep the grass short.
Common phrases
build a solar farm · utility-scale solar · ground-mounted solar farm · solar farm developer
Solar panels installed on the roofs of homes, offices, factories or warehouses, mainly to supply the building's own electricity needs.
Where you use it
A typical example of distributed generation and self-consumption. Rooftop solar is installed, sized to the building's load and often combined with net metering or a battery. Common phrases: rooftop solar system, rooftop PV, commercial and industrial (C&I) rooftop projects.
Examples
Our rooftop solar system covers about 35 percent of the factory's electricity use.
Before we installed rooftop solar, an engineer checked whether the roof could carry the extra weight.
Common phrases
install rooftop solar · rooftop solar system · rooftop PV · commercial rooftop project
The power output of a solar system under standard test conditions, used to state the size of a PV installation. It is written kWp; larger plants use MWp.
Where you use it
Used in quotes, datasheets and project documents: a 10 kWp rooftop system, a 60 MWp solar farm. Standard test conditions are 1,000 W/m² of sunlight at a cell temperature of 25 °C, so real output is usually lower. Annual yield is often given in kWh per kWp.
Examples
A 10 kilowatt peak system on this roof should produce about 14,000 kWh a year.
Prices for small systems are quoted per kilowatt peak, for example 900 euros per kWp.
Usage note
Wp, kWp and MWp are not official SI units, but they are standard in the solar industry. Do not mix up kWp (power) and kWh (energy).
Common phrases
kWp system · per kilowatt peak · MWp solar farm · specific yield in kWh/kWp
A thin semiconductor device, usually made of silicon, that produces electricity when light falls on it. Many cells connected together make up a solar panel.
Where you use it
Used in manufacturing, research and technical specifications. Cells are produced, tested, connected in strings and laminated into modules. Engineers talk about cell efficiency and cell technologies such as monocrystalline, PERC, TOPCon and heterojunction (HJT).
Examples
Each solar cell produces only about half a volt, so cells are connected in series.
The new factory will produce solar cells as well as modules.
Common phrases
silicon solar cell · cell efficiency · monocrystalline cell · solar cell manufacturing
The power of sunlight falling on a surface at a given moment, measured in watts per square metre (W/m²). It sets how much a solar panel can produce at that time.
Where you use it
Used in solar design, monitoring and performance reports. Irradiance is measured on site with a pyranometer. Global horizontal irradiance (GHI) and plane-of-array irradiance (POA) are common terms. Clear midday sun gives roughly 1,000 W/m².
Examples
Output dropped at 2 p.m. because clouds cut the irradiance to 300 W/m².
We compare the plant's output with the measured irradiance to calculate the performance ratio.
Usage note
Irradiance is power (W/m²); irradiation, also called insolation, is the energy collected over time (kWh/m²). The words look similar but are not interchangeable.
Common phrases
solar irradiance · global horizontal irradiance · measure irradiance · plane-of-array irradiance
The amount of electricity a solar or wind plant produces, or is expected to produce, over a period, usually a year. It is the basis of revenue forecasts.
Where you use it
Common in project finance and technical due diligence. An energy yield assessment estimates annual output; banks look at P50 and P90 values, the output expected to be exceeded with 50 and 90 percent probability. Specific yield is the yield per kWp.
Examples
The energy yield assessment predicts 1,650 kWh per kWp in the first year.
Actual energy yield was 4 percent below the P50 estimate because of a cloudy spring.
Common phrases
energy yield assessment · annual energy yield · specific yield · P50 and P90 yield
A tall machine with large blades that turn in the wind and drive a generator to produce electricity. Modern turbines often stand on towers more than 100 metres high.
Where you use it
Used by developers, engineers and technicians. A turbine is erected or installed, rated at a given power, maintained and later repowered (replaced with a newer model). Its main parts are the tower, nacelle, rotor, blades and generator.
Examples
The new wind turbines are rated at 6 MW each, almost twice the size of the old ones.
Technicians climb each wind turbine twice a year for routine maintenance.
Usage note
A windmill traditionally grinds grain or pumps water; for a machine that makes electricity, professionals say wind turbine.
A group of wind turbines built in the same area and connected together, feeding their electricity into the grid through a shared substation.
Where you use it
The usual term in English; wind park and wind power plant are also used. A wind farm is developed, built, commissioned and later repowered. Developers usually measure the wind at the site for a year or more before investing.
Examples
The wind farm has 20 turbines with a total capacity of 100 MW.
We installed a met mast to measure wind speeds at the planned wind farm site.
Usage note
Turkish 'rüzgar çiftliği' is a word-for-word translation of wind farm; formal Turkish documents prefer RES (rüzgar enerjisi santrali).
Common phrases
onshore wind farm · offshore wind farm · develop a wind farm · wind farm site
Wind power produced by turbines built at sea, either fixed to the seabed or on floating platforms, where winds are stronger and steadier than on land.
Where you use it
A major industry in northern Europe that is growing in other regions too. People talk about offshore wind farms, fixed-bottom and floating offshore wind, export cables that bring the power to shore, and special installation vessels and ports.
Examples
Some offshore wind turbines are now rated above 15 MW each.
Floating offshore wind could open up deep waters such as the Mediterranean.
Wind power produced by turbines built on land, often on hills, plains or coastal areas. It is usually cheaper and quicker to build than offshore wind.
Where you use it
Used to separate land-based projects from offshore ones: onshore wind farms, onshore wind capacity, onshore turbines. Typical issues are permits, land use, noise, visual impact and access roads for transporting the blades.
Examples
Onshore wind remains one of the cheapest sources of new electricity.
Transporting 80-metre blades to onshore wind sites in the mountains takes careful planning.
One of the long, curved arms, usually three, fixed to the hub of a wind turbine. Its shape lets the wind turn the rotor, which drives the generator.
Where you use it
Usually just called blades. Blades are made of glass-fibre or carbon-fibre composites; they are transported, lifted, inspected (often by drones), repaired and recycled. Leading-edge erosion is a common maintenance issue. Blade length sets the rotor diameter.
Examples
Drone inspections found cracks on one rotor blade after the storm.
Longer rotor blades capture more energy at low wind speeds.
The large housing on top of a wind turbine tower that contains the main machinery, such as the gearbox, generator, shaft and control systems.
Where you use it
Used by technicians, engineers and manufacturers. The nacelle is lifted onto the tower by crane and turns to face the wind (yaw). Technicians work inside the nacelle during maintenance. Direct-drive turbines have no gearbox in the nacelle.
Examples
The crane lifted the 100-tonne nacelle onto the tower in under an hour.
A sensor in the nacelle detected high gearbox temperatures.
Usage note
Pronounced 'nuh-SELL', with the stress on the second syllable.
Common phrases
nacelle assembly · inside the nacelle · lift the nacelle · nacelle cover
The lowest wind speed at which a wind turbine starts to produce usable electricity, typically about 3 metres per second for modern machines.
Where you use it
Found on turbine datasheets and power curves together with rated speed (where the turbine reaches full power) and cut-out speed (where it stops to protect itself, often around 25 m/s). Engineers use these values to estimate the energy yield of a site.
Examples
With a cut-in speed of 3 m/s, the turbine produces power for most of the year at this site.
Check the cut-in speed, rated speed and cut-out speed on the power curve.
Electricity produced by water flowing through turbines, usually from a river or from a reservoir behind a dam. It is the oldest large-scale renewable power source.
Where you use it
Also called hydroelectric power or simply hydro ('hydro output was low this year'). Reservoir plants behind dams can store water; run-of-river plants use the natural flow. Output depends on rainfall and snowmelt.
Examples
After a dry winter, hydropower output dropped by almost a third.
Reservoir hydropower can respond within minutes when demand rises.
Electricity produced from the heat released when uranium atoms are split in a reactor. It produces almost no carbon dioxide while running.
Where you use it
Used in energy policy, engineering and public debate. Countries build, expand or phase out nuclear power. Common phrases: nuclear power plant (NPP), nuclear capacity, nuclear safety. Supporters stress low carbon and steady output; critics point to cost, waste and safety.
Examples
Nuclear power provides steady output around the clock.
The first unit of the nuclear power plant is expected to start commercial operation next year.
Usage note
Pronounce nuclear as 'NOO-klee-er'. The form 'NOO-kyuh-ler' is often heard but widely considered a mistake.
Common phrases
nuclear power plant · nuclear capacity · nuclear safety · phase out nuclear power
A large wall built across a river to hold back water and create a reservoir. In hydropower plants, the stored water flows through turbines to generate electricity.
Where you use it
Used in hydropower, water management and environmental discussions. Dams are built, raised and filled, and water is released. Related words: reservoir (baraj gölü), spillway (dolusavak), penstock (cebri boru), water level. A dam plant can store water and produce on demand, unlike most run-of-river plants.
Examples
The water level behind the dam is 20 percent lower than last year.
The dam releases more water in the evening, when electricity prices are highest.
Common phrases
build a dam · dam reservoir · behind the dam · dam safety
The part of a nuclear power plant where a controlled chain reaction splits uranium atoms and produces heat, which is used to make steam for the turbines.
Where you use it
Reactors are designed, built, started up, refuelled and shut down. Most power reactors are pressurised water reactors (PWR). Small modular reactors (SMRs) are a newer design discussed in many countries. Each reactor with its turbine is usually called a unit.
Examples
The nuclear reactor was shut down for refuelling and inspection.
Each nuclear reactor at the site will have a capacity of about 1,200 MW.
Common phrases
pressurised water reactor · small modular reactor · shut down a reactor · reactor core · reactor unit
Hydrogen produced by splitting water in an electrolyser powered by renewable electricity, so that its production releases almost no carbon dioxide.
Where you use it
Discussed for steel, fertiliser, chemicals, shipping and long-term storage. It is compared with grey hydrogen (made from natural gas) and blue hydrogen (from gas with carbon capture). Electrolysers are sized in MW, and the cost per kilogram is the key number.
Examples
The steel plant plans to replace part of its natural gas with green hydrogen.
In most markets, green hydrogen is still more expensive than grey hydrogen.
Common phrases
green hydrogen production · electrolyser capacity · grey hydrogen · blue hydrogen · hydrogen economy
Organic material from plants and animals, such as wood chips, crop residues and manure, that is burned or turned into gas or fuel to produce energy.
Where you use it
Used in power, heat and policy discussions. Biomass plants burn solid fuel; biogas plants turn waste into gas through anaerobic digestion. Whether biomass is really low-carbon depends on where the material comes from, so sustainability criteria matter.
Examples
The biomass plant burns olive pits and other farm waste from the region.
Biomass from the dairy farm's manure feeds a biogas unit that makes electricity and heat.
Energy from heat inside the Earth, brought to the surface as hot water or steam through wells and used to generate electricity or to heat buildings and greenhouses.
Where you use it
Used in energy planning, drilling and plant engineering. Developers drill production and reinjection wells and build flash or binary plants. Geothermal gives steady output day and night. Turkey is one of the world's largest producers of geothermal electricity, mainly in western Anatolia.
Examples
Geothermal energy from these wells also heats 3,000 homes in the town.
Geothermal energy projects carry a high drilling risk in the early stages.
Common phrases
geothermal power plant · geothermal well · reinjection well · binary cycle plant · geothermal heating
A heavy, slightly radioactive metal used as fuel in nuclear reactors. For most reactors it is enriched so that the share of the isotope U-235 rises to about 3 to 5 percent.
Where you use it
Used in nuclear fuel supply, mining and policy. Uranium is mined, milled, converted, enriched and made into fuel assemblies. Prices are quoted per pound of U3O8 (yellowcake). Natural uranium contains only about 0.7 percent U-235.
Examples
Fresh uranium fuel is loaded into the reactor every 18 months.
Most uranium for power reactors is enriched to below 5 percent U-235.
Radioactive material left over from nuclear power and other nuclear activities, especially spent fuel from reactors, which must be kept safely isolated for very long periods.
Where you use it
Technical texts usually say radioactive waste or spent fuel. Waste is classified as low-, intermediate- or high-level. Spent fuel is first cooled in pools, then kept in dry casks, and finally planned for deep geological repositories.
Examples
The plant's nuclear waste is kept in dry casks on site until a final repository is ready.
Public concern about nuclear waste often delays new reactor projects.
Technologies that capture energy when it is available and release it later when it is needed, such as batteries, pumped hydro and thermal storage.
Where you use it
A fast-growing topic in projects, regulation and investment. Storage is deployed, paired with solar or wind, and sized in MW (power) and MWh (energy). People talk about storage capacity, storage duration (for example four-hour storage) and long-duration storage.
Examples
Energy storage lets us shift solar power from noon to the evening peak.
The tender requires a 50 MW / 200 MWh energy storage system.
Common phrases
energy storage system · storage capacity · long-duration storage · pair with storage
Storing electricity in large rechargeable batteries so it can be released later, for example during the evening peak or when the grid needs fast support.
Where you use it
In projects the system is called a battery energy storage system (BESS), usually built in containers. A battery is charged and discharged, sized in MW and MWh, and earns money from price arbitrage, frequency services or capacity payments. It can stand alone or sit next to a solar or wind plant.
Examples
The battery storage charges at midday, when solar power is cheap, and discharges in the evening.
We are adding 40 MWh of battery storage to the existing wind farm.
Common phrases
battery energy storage system · co-located battery storage · standalone battery · charge and discharge
Storing energy by pumping water up to a higher reservoir when electricity is cheap or plentiful, then releasing it through turbines to generate power when needed.
Where you use it
A mature technology used for decades, also called pumped storage or pumped-storage hydropower (PSH). Plants are sized in MW and in hours of storage. They need two reservoirs at different heights and take years to build, but they last for many decades.
Examples
The pumped hydro storage plant pumps water uphill at midday, when solar power is cheap, and generates during the evening peak.
Pumped hydro storage needs suitable geography, so only a few sites are possible.
How full a battery is at a given moment, shown as a percentage of its usable capacity, from 0 percent (empty) to 100 percent (full).
Where you use it
Shortened to SoC or SOC. Battery management systems and operators track the state of charge constantly and keep it within limits, for example between 10 and 90 percent, to protect battery life. Related terms are depth of discharge (DoD) and state of health (SoH).
Examples
The state of charge was 85 percent at 5 p.m., ready for the evening peak.
Keep the state of charge above 20 percent to reserve capacity for frequency services.
Common phrases
state of charge (SoC) · depth of discharge · state of health · battery management system
A rechargeable battery in which lithium ions move between the electrodes. It is used in phones, electric vehicles and most new grid-scale storage projects.
Where you use it
Often shortened to Li-ion. In grid storage the main chemistry today is lithium iron phosphate (LFP), valued for safety and long life. Engineers talk about cell chemistry, cycle life, degradation, thermal runaway and fire safety.
Examples
The project uses lithium-ion batteries with LFP cells for better fire safety.
A lithium-ion battery slowly loses capacity with every charge cycle.
The share of the energy put into a storage system that can be taken out again after losses in charging, storing and discharging, shown as a percentage.
Where you use it
A key performance figure in storage contracts and tenders, shortened to RTE. Lithium-ion systems typically reach about 85 to 90 percent and pumped hydro about 70 to 80 percent, while storing energy as hydrogen gives much less.
Examples
With 88 percent round-trip efficiency, we get 88 MWh back for every 100 MWh we store.
The contract guarantees a round-trip efficiency of at least 85 percent in the first year.
The amount of energy used by a person, building, machine, company or country over a period, for example a day, a month or a year.
Where you use it
Common in efficiency projects, sustainability reports and statistics. Energy consumption rises, falls, is reduced, measured and monitored. For electricity only, people say electricity consumption; for a single device, power consumption usually means the power it draws in watts.
Examples
After the LED upgrade, the factory's energy consumption fell by 18 percent.
We monitor energy consumption in every building through the dashboard.
Usage note
Demand and consumption are different: demand is how much power is needed at a given moment (MW); consumption is the total energy used over a period (MWh).
Common phrases
reduce energy consumption · annual energy consumption · electricity consumption · monitor energy consumption
Using less energy to do the same job, for example to heat a building, light a room or run a machine, thanks to better equipment, design or habits.
Where you use it
Common in policy, buildings and industry. You improve or invest in energy efficiency; there are energy efficiency measures, projects, standards and labels. It is often called the cheapest clean energy source, because saved energy needs no new supply.
Examples
The energy efficiency project paid for itself in less than three years.
New regulations set minimum energy efficiency standards for electric motors.
Usage note
Efficiency means doing the same job with less energy; energy saving or conservation can also mean simply using less, for example turning the heating down.
Common phrases
improve energy efficiency · energy efficiency measures · energy efficiency standards · invest in energy efficiency
An electric device that moves heat from the air, ground or water into a building to heat it, or out of it to cool it, delivering more heat than the electricity it uses.
Where you use it
Central to the electrification of heating. Types include air-source, ground-source and water-source heat pumps. Efficiency is given as the coefficient of performance (COP): a COP of 3 means three units of heat for one unit of electricity.
Examples
Replacing the old gas boiler with a heat pump halved the building's heating emissions.
Ground-source heat pumps cost more to install but work more efficiently in cold weather.
Common phrases
air-source heat pump · ground-source heat pump · install a heat pump · coefficient of performance
Material placed in walls, roofs, floors or around pipes to reduce heat loss in winter and heat gain in summer, so less energy is needed for heating and cooling.
Where you use it
Used in building renovation, energy audits and efficiency programmes. Insulation is installed, added or improved and is described by its thickness or U-value. Typical phrases: wall insulation, roof insulation, loft insulation (UK), poorly insulated buildings.
Examples
Adding roof insulation was the cheapest measure in the energy audit.
With such poor insulation, the heating runs all day and the rooms are still cold.
Usage note
In electrical work, insulation also means the plastic or rubber layer around a cable. Do not confuse it with isolation, which means separating equipment from the power supply.
A detailed inspection of how a building or industrial site uses energy, showing where energy is wasted and which measures would save energy and money.
Where you use it
Carried out by energy auditors or consultants and often required by law for large companies. The audit report lists measures with their cost, savings and payback period. Typical findings include compressed air leaks, poor insulation, old motors and inefficient lighting.
Examples
The energy audit found that compressed air leaks were wasting 12 percent of the plant's electricity.
We carry out an energy audit every four years, as the law requires.
Common phrases
carry out an energy audit · energy audit report · energy auditor · payback period
An official document that rates a building's energy efficiency, usually on a scale from A (most efficient) to G, and is needed when a building is built, sold or rented.
Where you use it
Shortened to EPC in the UK and many EU countries. A building has, gets or needs an EPC rating, and buyers and tenants compare ratings. In Turkey the equivalent document is called Enerji Kimlik Belgesi (EKB).
Examples
The flat has an energy performance certificate rating of C.
After the renovation, the new energy performance certificate moved the office from E to B.
Usage note
In energy projects EPC usually means engineering, procurement and construction, the main contract for building a plant. Check the context.
Common phrases
EPC rating · energy performance certificate · energy rating · A-rated building
A company that supplies electricity, gas or water to the public and often owns or runs the network that delivers it. In energy texts it usually means a power company.
Where you use it
Very common in American English and market reports: utility company, electric utility, utility customers. Utility-scale describes large projects that sell power to the grid rather than to a single building. Utility bills cover electricity, gas and water.
Examples
The utility raised its residential rates by 8 percent this year.
Most of our projects are utility-scale solar plants above 50 MW.
Usage note
In everyday English, utilities are also the services themselves (electricity, gas, water), as in 'Rent includes utilities.'
Common phrases
utility company · electric utility · utility-scale · utility bills · utility customers
The set of prices and rules that decides how much a customer pays for electricity or gas, for example per kWh, per month or by time of day.
Where you use it
Used by regulators, suppliers and customers. Tariffs are set, approved, raised and cut. Common types are residential and commercial tariffs, flat-rate tariffs and time-of-use tariffs with different peak and off-peak prices. Americans often say rate instead.
Examples
With a time-of-use tariff, running the dishwasher at night saves money.
The regulator approved new electricity tariffs for the next quarter.
Usage note
In trade, a tariff is a tax on imports (gümrük vergisi). In energy texts it means a price schedule.
An electricity or gas meter that records consumption at short intervals and sends the data automatically to the supplier or network operator.
Where you use it
Common in customer service, utility projects and regulation. Smart meters are installed, rolled out and read remotely. They make time-of-use tariffs and demand response possible and replace manual meter readings.
Examples
Since we got a smart meter, the bill is based on actual readings, not estimates.
The smart meter rollout will reach every household in the region by 2028.
Common phrases
install a smart meter · smart meter rollout · smart meter data · remote meter reading
A long-term contract in which a buyer, such as a utility or a large company, agrees to purchase electricity from a specific power project at an agreed price.
Where you use it
Almost always shortened to PPA. Corporate PPAs let companies buy renewable power directly; they can be physical or virtual (financial). PPAs are negotiated, signed and priced per MWh, usually for 10 to 20 years, and they help projects get bank financing.
Examples
The car maker signed a ten-year power purchase agreement with a local wind farm.
Without a power purchase agreement, the bank would not finance the solar project.
The market where electricity is traded in large volumes between generators, suppliers, traders and large consumers before it reaches end customers.
Where you use it
Wholesale prices are quoted per MWh and can change every hour or even every 15 minutes. The wholesale market includes day-ahead and intraday markets, futures and bilateral contracts. Traders talk about wholesale prices rising, spiking, falling or turning negative.
Examples
Wholesale market prices fell below zero for several hours on Sunday afternoon.
Large factories can buy directly on the wholesale market instead of from a supplier.
Common phrases
wholesale electricity price · wholesale market price · trade on the wholesale market · wholesale price spike
A support scheme that guarantees renewable energy producers a fixed price for each kWh they feed into the grid, usually for 10 to 20 years.
Where you use it
Shortened to FiT. Feed-in tariffs helped launch solar and wind in many countries; later many moved to auctions, feed-in premiums or contracts for difference. Projects qualify for, receive or lose the feed-in tariff, and the rate is set per kWh or MWh.
Examples
Under the old feed-in tariff, the plant sells every megawatt-hour at a fixed price until 2030.
Several countries replaced feed-in tariffs with competitive auctions.
Common phrases
feed-in tariff scheme · qualify for a feed-in tariff · feed-in tariff rate · feed-in premium
An exchange market where electricity for each hour, or quarter-hour, of the next day is bought and sold, usually through bids that close around midday.
Where you use it
The main reference for short-term electricity prices. Participants submit bids and offers; the market clears and sets a price for each hour, called the market clearing price. Later changes are traded on the intraday market, and real-time imbalances are settled in the balancing market.
Examples
Day-ahead market prices peaked at 7 p.m., just after sunset.
Our trading desk submits bids to the day-ahead market before noon every day.
Short for levelized cost of electricity: the average cost of producing one MWh over a plant's whole life, including building, financing, fuel and maintenance costs.
Where you use it
The standard figure for comparing technologies. LCOE is calculated, quoted in currency per MWh and compared across solar, wind, gas and nuclear. It is useful but simple: it ignores when the power is produced and the extra grid or storage costs.
Examples
The LCOE of utility-scale solar is now below that of new gas plants in many markets.
A lower interest rate would cut the project's LCOE by about 10 percent.
Usage note
LCOE is read letter by letter: L-C-O-E.
Common phrases
calculate the LCOE · low LCOE · LCOE per MWh · levelized cost of electricity
A billing system in which electricity that a customer's solar panels send to the grid is subtracted from the electricity they take from it, so they pay only for the difference.
Where you use it
Important for the economics of rooftop solar. Customers are eligible for net metering, and netting may be hourly, monthly or yearly. Many countries are replacing it with net billing, where exported power is paid at a lower price than imported power.
Examples
With net metering, the energy we export at noon is deducted from what we use in the evening.
The new rules move households from net metering to hourly net billing.
Common phrases
net metering scheme · eligible for net metering · net billing · export to the grid
An electronic certificate proving that one MWh of electricity was produced from a specific, usually renewable, source. Companies use them to back up claims of using green power.
Where you use it
Called guarantees of origin (GOs) in Europe and renewable energy certificates (RECs) in the US; I-RECs are common internationally. Certificates are issued, transferred, bought and cancelled once the green claim is made.
Examples
We buy guarantees of origin to cover all of our office electricity.
Each guarantee of origin is cancelled once the green claim is made.
Common phrases
issue guarantees of origin · cancel a certificate · renewable energy certificate · I-REC · green claim
Changing when or how much electricity consumers use in response to price signals or requests from the grid operator, for example reducing factory load during a peak.
Where you use it
Shortened to DR. Large consumers, aggregators and smart home devices take part in demand response programmes and are paid for their flexibility. Common phrases: demand-side flexibility, load shifting, peak shaving and demand response event.
Examples
During the heatwave, our demand response contract required the plant to cut 5 MW for two hours.
Smart thermostats make demand response possible in ordinary homes.
Carbon dioxide released into the air, mainly by burning coal, oil and gas. The term is often used loosely for all greenhouse gas emissions.
Where you use it
Used in climate policy, ESG reports and project assessments. Emissions are cut, reduced, offset, measured, reported and verified. Values are given in tonnes of CO2 or CO2 equivalent (CO2e).
Examples
Switching from coal to gas cut the plant's carbon emissions by about half.
We report our carbon emissions every year in the sustainability report.
Usage note
In this sense emission is usually plural: say 'reduce emissions', not 'reduce emission'.
The long-term shift of an economy's energy system away from fossil fuels towards renewable and other low-carbon sources, together with electrification and efficiency.
Where you use it
A key phrase in strategy documents, conferences and news. Countries and companies lead, speed up, finance or manage the energy transition. A just transition is one that also protects the workers and communities that depend on coal and other fossil industries.
Examples
Grid investment has become the bottleneck of the energy transition.
Our strategy explains how the company will finance its part in the energy transition.
Common phrases
accelerate the energy transition · just transition · clean energy transition · finance the energy transition
A state in which the greenhouse gases a country or company puts into the air are balanced by the amount it removes, so that its overall contribution is zero.
Where you use it
Used in targets and pledges: reach net zero by 2050, a net-zero target, net-zero emissions. Before a noun it is hyphenated (net-zero strategy). Getting there usually needs deep emission cuts plus removals, for example by forests or carbon capture.
Examples
The group has committed to reaching net zero across its operations by 2045.
Our net-zero plan starts with switching all sites to renewable electricity.
Usage note
Carbon neutral is close in meaning, but it is often used for products or events and may rely mostly on offsets; net zero usually implies deep cuts first.
Common phrases
reach net zero · net-zero target · net-zero emissions · net-zero pathway
A gas in the atmosphere, such as carbon dioxide, methane or nitrous oxide, that traps heat and contributes to global warming.
Where you use it
Shortened to GHG in reports: GHG emissions, GHG inventory, GHG Protocol. Different gases are converted into CO2 equivalent (CO2e) so they can be added up. Companies report their emissions as Scope 1, 2 and 3.
Examples
Methane is a much stronger greenhouse gas than CO2 over a 20-year period.
The audit covers all greenhouse gas emissions from our power plants.
Common phrases
greenhouse gas emissions · GHG inventory · reduce greenhouse gases · CO2 equivalent
The total amount of greenhouse gases caused directly and indirectly by a person, product, company or event, expressed in tonnes of CO2 equivalent.
Where you use it
Common in sustainability reports, marketing and supplier questionnaires. You calculate, measure, reduce or shrink a carbon footprint. European buyers increasingly ask suppliers for the footprint of each product.
Examples
Our customer in Germany asked for the carbon footprint of each product we ship.
Reducing the carbon dioxide emissions of an economy, sector or company, for example by switching to renewable power, electrifying heat and transport and improving efficiency.
Where you use it
A core word in policy and corporate strategy. People decarbonize the power sector, industry or transport, set decarbonization targets and talk about hard-to-abate sectors such as steel and cement. The British spelling is decarbonisation.
Examples
Decarbonization of the power sector is moving faster than in industry.
Our decarbonization roadmap sets targets for 2030 and 2040.
Common phrases
decarbonization target · decarbonize the power sector · hard-to-abate sectors · decarbonization roadmap
A cost put on each tonne of carbon dioxide emitted, through a carbon tax or an emissions trading system, to encourage companies to cut their emissions.
Where you use it
Expressed per tonne of CO2, for example 70 euros per tonne. Carbon pricing is the general policy; the carbon price is the actual level. Exporters to the EU follow the Carbon Border Adjustment Mechanism (CBAM), which puts a carbon price on some imported goods.
Examples
A higher carbon price makes coal plants more expensive to run than gas plants.
We assume a carbon price of 80 euros per tonne in all new investment decisions.
A market-based scheme that sets a cap on total emissions and lets companies buy and sell allowances, each giving the right to emit one tonne of CO2.
Where you use it
Shortened to ETS; the approach is also called cap and trade. Companies surrender allowances for their emissions each year, and the cap falls over time. The EU ETS, launched in 2005, covers power plants, heavy industry and aviation. Turkey has also begun setting up a national ETS.
Examples
Under the emissions trading system, the plant must buy extra allowances if it exceeds its free allocation.
Allowance prices in the emissions trading system rose sharply this quarter.
Common phrases
EU ETS · emission allowances · cap and trade · free allocation · surrender allowances
Technology that captures carbon dioxide from power plants or factories before it reaches the air, then transports it and stores it permanently deep underground.
Where you use it
Shortened to CCS; when the CO2 is used, for example in industry, it becomes CCUS (carbon capture, utilisation and storage). Discussed mainly for cement, steel, chemicals and gas plants. Projects are judged by capture rate and tonnes stored per year; cost and scale are frequent concerns.
Examples
The cement plant plans to add carbon capture and storage by 2032.
Carbon capture and storage could capture about 90 percent of the CO2 in the plant's flue gas.
Common phrases
CCS project · capture rate · CO2 storage site · carbon capture, utilisation and storage
A country's ability to get enough energy, reliably and at affordable prices, without serious disruption from supply cuts, price shocks or technical failures.
Where you use it
A central idea in energy policy and diplomacy. Governments strengthen energy security by diversifying suppliers and routes, building storage and developing domestic sources. Security of supply is a close synonym.
Examples
Domestic renewables strengthen energy security because they reduce fuel imports.
Gas storage is essential for energy security during cold winters.
Common phrases
strengthen energy security · security of supply · diversify supply · import dependence
To stop using something gradually over a planned period, for example coal power, fossil fuel subsidies or inefficient light bulbs.
Where you use it
Very common in policy and news. The verb is separable: phase out coal or phase coal out. The noun is written with a hyphen: a coal phase-out, a nuclear phase-out. The opposite is phase in; a phase-down means reducing something, not ending it.
Examples
The government plans to phase out coal power by 2035.
Fossil fuel subsidies will be phased out over five years.
Common phrases
phase out coal · coal phase-out · nuclear phase-out · phase in · phase-down
Money or other financial help that a government gives to lower the cost of energy for consumers or to support particular technologies or producers.
Where you use it
Used both for renewable support and for keeping fossil fuel prices low. Subsidies are granted, paid, cut, reformed or phased out. Related forms include tax credits, grants, guaranteed prices and capacity payments.
Examples
Household electricity prices are kept low through a large government subsidy.
The new subsidy covers 30 percent of the cost of installing a heat pump.
Common phrases
energy subsidies · fossil fuel subsidies · receive a subsidy · cut subsidies · government subsidy
Ten questions from this glossary. Pick the right meaning for each term and see your score.
How to learn energy & renewables vocabulary
Read real texts from the field: annual reports of grid operators and energy agencies, project feasibility studies, inverter and turbine datasheets, market news and sustainability reports use this vocabulary in its natural context.
Keep power and energy apart from the start. Power is a rate, measured in kW or MW; energy is an amount, measured in kWh or MWh. Saying 'a 5 MW plant produced 9,000 MWh last year' correctly is a quick sign of a professional.
Learn the verbs that go with each term, not just the nouns: a plant is commissioned, comes online and is later decommissioned; output is ramped up or curtailed; coal is phased out; power is fed into the grid.
Practice reading numbers and units aloud: 'two point five megawatts', 'eighty euros per megawatt-hour', 'three hundred eighty kilovolts'. English uses a decimal point and a comma for thousands, the opposite of Turkish.
Match English terms with the Turkish abbreviations you already use, such as GES (solar farm), RES (wind farm), HES (hydropower plant), YEKDEM (feed-in tariff) and GÖP (day-ahead market), so you can explain the Turkish market to foreign colleagues.
Frequently asked questions
How can I learn English for the energy sector?
Read real texts from the field and notice how the words are used: reports from grid operators and energy agencies, feasibility studies, equipment datasheets, market news and company sustainability reports. Learn each term with its usual partners (commission a plant, feed into the grid, curtail output, sign a PPA) and use new words right away in your own emails, reports and meetings.
Which energy terms should I learn first?
Start with the words you hear every day: renewable energy, generation, power plant, grid, kWh, MW, installed capacity, solar panel, wind turbine, transmission line, substation, load, peak demand, energy storage, energy efficiency, tariff and carbon emissions. Then move on to markets, storage, policy and the technical details of each technology. The terms in this glossary follow the same order, from most to least essential.
What is the difference between kW and kWh?
A kilowatt (kW) measures power, the rate at which energy is produced or used at a given moment. A kilowatt-hour (kWh) measures energy, the amount produced or used over time. A 2 kW heater that runs for 3 hours uses 6 kWh. Plants are described by their power (a 50 MW wind farm), while bills and annual output use energy (120,000 MWh a year).
How do I say GES, RES and HES in English?
GES is usually a solar power plant, solar farm or solar park; RES is a wind farm or wind power plant; HES is a hydropower plant or hydroelectric power plant, sometimes shortened to HPP; JES is a geothermal power plant. English speakers do not know these Turkish abbreviations, so write the full English term and, if you need to, explain the Turkish abbreviation once in brackets.
