Glossary: Electricity Terms Explained
This glossary defines 22 electricity terms used across World Power Monitor, from market terms such as day-ahead price and negative price to grid terms such as balancing authority and interconnector. Each entry is a short definition, 19 with a worked example drawn from real data on this build, and links to the pages that use the term.
Key Facts
- The glossary defines 22 terms in plain language, each two to four sentences.
- 19 of the 22 entries include a worked example computed from this build's own data, with a link back to the page it came from.
All Terms
22 terms- Balancing Area Export/Import A balancing area's export or import is the net flow of electricity across its interconnectors with neighbouring areas over a period: positive when it sent more than it received (a net exporter), negative when it received more than it sent (a net importer).
- Balancing Authority A balancing authority is the operator responsible for keeping electricity supply and demand matched in real time within its own area of the United States grid, the American equivalent of a European bidding zone but built around reliability rather than a single market price.
- Base Load Base load is the minimum level of electricity demand a grid sees over a day or a year, the floor that must be met continuously.
- Bidding Zone A bidding zone is the area within which wholesale electricity trades at a single market price for each hour, used across Europe's day-ahead markets.
- Capacity Factor Capacity factor is how much a power plant or fleet actually generated over a year, divided by what it would have generated running at full output every hour of that year.
- Capacity vs Generation Installed capacity is how much power a fleet of plants could produce at any instant if run flat out, measured in gigawatts (GW).
- Carbon Intensity Carbon intensity measures how much CO2 is emitted for each unit of electricity generated, usually in grams of CO2 per kilowatt hour.
- Curtailment Curtailment is when a grid operator deliberately reduces output from a generator, most often wind or solar, even though the resource needed to generate more is available.
- Data Coverage Data coverage is the share of world electricity demand actually behind a figure, stated explicitly whenever a page combines many countries that do not all report at the same time.
- Day-Ahead Price The day-ahead price is the wholesale price set one day in advance for each hour of electricity delivery in a bidding zone, from an auction that matches generation offers against consumption bids for every hour of the next day.
- Duck Curve The duck curve describes the shape of net demand (demand minus solar and wind output) across a day on a grid with a lot of solar power: it dips around midday as solar output peaks, then rises sharply in the evening as the sun sets and people get home.
- Ember Data vs Operator Data World Power Monitor draws on two layers of data that are never combined into one figure.
- Energy Transition The energy transition is the ongoing shift in how electricity is generated, away from fossil fuels such as coal and gas and toward low carbon sources such as wind, solar, hydro and nuclear.
- Forecast Error Forecast error is the difference between the electricity demand a grid operator predicted a day ahead and what was actually recorded, usually shown as a percentage of actual demand.
- Generation Mix A generation mix is the breakdown of a country's or grid's electricity output by fuel or technology over a period, usually shown as a percentage share of the total.
- Interconnector An interconnector is a transmission line that lets electricity flow between two grid areas, whether two countries, two US balancing authorities, or two European bidding zones.
- Low Carbon Share Low carbon share is the percentage of electricity generated from sources that emit little or no CO2 while running: nuclear, hydro, wind, solar, bioenergy and geothermal.
- Negative Price A negative price happens when a wholesale electricity price clears below zero for an hour: generators pay to keep running rather than switch off.
- Net Generation vs Demand Net generation is the electricity a country or grid actually produced, generation minus a plant's own use, while demand is what it consumed.
- Peak Demand Peak demand is the highest level of electricity demand recorded over a period, whether a single day or the whole time a grid has been measured.
- Retail vs Wholesale Price The wholesale price is what generators are paid and large buyers pay for electricity in bulk, set by markets such as the day-ahead auction, and it changes hour by hour.
- TWh, GWh and MWh TWh (terawatt hour), GWh (gigawatt hour) and MWh (megawatt hour) all measure the same thing, electrical energy, at different scales: 1 TWh equals 1,000 GWh, and 1 GWh equals 1,000 MWh.