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


Implementing Agreements, also known as Multilateral Technology Initiatives or Energy Technology Initiatives (of the IEA). List of initiatives 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)


Industry Advisory Board (of the IEA)


internal combustion engine


Initial Contingency Response Plan


information and communications technologies


Innovation China-United Kingdom


In-Depth Reviews (IEA publications focusing on specific countries)


integrated energy policy


integrated gasification combined cycle


International Low-Carbon Energy Technology Platform


international oil company


industries of the future


initial public offering


independent power producer


intellectual property rights


internal rates of return


in situ leaching


a sector that includes fuel used within the manufacturing and construction industries. Key industry sectors include iron and steel, chemical and petrochemical, non-metallic minerals, and pulp and paper. Use by industries for the transformation of energy into another form or for the production of fuels is excluded and reported separately under other energy sector. Consumption of fuels for the transport of goods is reported as part of the transport sector.

integrated gasification combined cycle

a technology in which a solid or liquid fuel (coal, heavy oil or biomass) is gasified, followed by use for electricity generation in a combined-cycle power plant. IGCC is widely considered a promising electricity generation technology, due to its potential to achieve high efficiencies and low emissions.

international aviation bunkers

This category includes the deliveries of aviation fuels to aircraft for international aviation. Fuels used by airlines for their road vehicles are excluded. The domestic/international split is determined on the basis of departure and landing locations and not by the nationality of the airline. For many countries this incorrectly excludes fuels used by domestically owned carriers for their international departures.

international marine bunkers

This category covers those quantities delivered to ships of all flags that are engaged in international navigation. The international navigation may take place at sea, on inland lakes and waterways, and in coastal waters. Consumption by ships engaged in domestic navigation is excluded. The domestic/international split is determined on the basis of port of departure and port of arrival, and not by the flag or nationality of the ship. Consumption by fishing vessels and by military forces is also excluded and included in residential, services and agriculture.