The following definitions reflect those used by the International Energy Agency (IEA); definitions used by other organisations and publications may vary.


transmission and distribution (of electricity)


tertiary amyl methyl ether


Energy Training & Capacity Building Programme (of the IEA)


Technology Collaboration Programmes, also known as Implementing Agreements, Multilateral Technology Initiatives or Energy Technology Initiatives (of the IEA). List of programmes as of 2015:

  • Advanced Fuel Cells (AFCIA)
  • Advanced Materials for Transportation (AMT IA)
  • Advanced Motor Fuels (AMF IA)
  • Bioenergy (Bioenergy IA)
  • Buildings and Community Systems (ECBCS IA)
  • Clean Coal Centre (CCC IA)
  • Climate Technology Initiative (CTI IA)
  • Co-operation on Tokamak Programmes (CTP IA)
  • Demand-Side Management (DSM IA)
  • District Heating and Cooling, including the Integration of Combined Heat and Power (DHC IA)
  • Efficient Electrical End-Use Equipment (4E IA) 
  • Electricity Networks Analysis, Research & Development (ENARD IA)
  • Emissions Reduction in Combustion (Combustion IA)
  • Energy Storage (ECES IA)
  • Energy Technology Data Exchange (ETDE IA)
  • Energy Technology Systems Analysis Programme (ETSAP IA)
  • Enhanced Oil Recovery (EOR IA)
  • Environmental, Safety and Economic Aspects of Fusion Power (ESE Fusion Power IA)
  • Fluidized Bed Conversion (FBC IA)
  • Fusion Materials (Fusion Materials IA)
  • Geothermal (Geothermal IA)
  • Greenhouse Gas (GHG IA) 
  • Heat Pumping Technologies (Heat Pumps IA)
  • High-Temperature Superconductivity on the Electric Power Sector (HTS IA)
  • Hybrid and Electric Vehicles (HEV IA)
  • Hydrogen (Hydrogen IA)
  • Hydropower (Hydropower IA)
  • Industrial Energy-Related Technologies and Systems (IETS IA)
  • Multiphase Flow Sciences (Multiphase IA)
  • Nuclear Technology of Fusion Reactors (NTFR IA)
  • Ocean Energy Systems (OES IA)
  • Photovoltaic Power Systems (PVPS IA)
  • Plasma Wall Interaction in TEXTOR (Textor IA)
  • Renewable Energy Technology Deployment (RETD IA)
  • Reversed Field Pinches (RFP IA)
  • Smart Grids
  • Solar Heating and Cooling (SHC IA)
  • SolarPACES  (SolarPACES IA)
  • Spherical Tori (Spherical Tori IA)
  • Stellarator-Heliotron Concept (Stellarator/Heliotron IA)
  • Wind Energy Systems (Wind IA)


total final consumption


tradable green certificate


total primary energy demand


total primary energy supply



technology transfer

(two definitions) the process of converting scientific findings from research laboratories into useful products by the private sector; second definition is used more in economic development literature and involves cross-border transmission of technology from one country to another.

total final consumption

the sum of consumption by the different end-use sectors. TFC is broken down into energy demand in the following sectors: industry, transport, buildings (including residential and services) and other (including agriculture and non-energy use). It excludes international marine and aviation bunkers, except at world level where it is included in the transport sector.

total primary energy demand

represents domestic demand only and is broken down into power generation, other energy sector and total final consumption.

total primary energy supply

equivalent to total primary energy demand. TPES represents inland demand only and, except for world energy demand, excludes international marine and aviation bunkers.

traditional biomass

the use of fuelwood, charcoal, animal dung and agricultural residues in stoves with very low efficiencies.


refers under IEA statistical purposes to fuels and electricity used in the transport of goods or persons within the national territory irrespective of the economic sector within which the activity occurs. This includes fuel and electricity delivered to vehicles using public roads or for use in rail vehicles; fuel delivered to vessels for domestic navigation; fuel delivered to aircraft for domestic aviation; and energy consumed in the delivery of fuels through pipelines. Fuel delivered to international marine and aviation bunkers is presented only at the world level and is excluded from the transport sector at the domestic level.


tonne = metric tonne = 1 000 kg


tonnes per year


thousand cubic feet


trillion cubic metres






terawatt hour