Energy Indicators for Sustainable Development: Guidelines and Methodologies International Atomic Energy Agency United Nations Department of Economic and Social Affairs International Energy Agency Eurostat European Environment Agency

Non-combustible renewables include geothermal, solar, wind, hydro, tide and wave 
energy. For geothermal energy, the energy quantity is the enthalpy of the geothermal 
heat entering the process. For solar, wind, hydro, tide and wave energy, the quantities 
entering electricity generation are equal to the electrical energy generated. Electricity 
is accounted for at the same heat value as electricity in final consumption (i.e. 1 TWh 
equals 0.086 Mtoe). Direct use of geothermal and solar heat, and heat from heat 
pumps is also included here. 
Nuclear represents the primary heat equivalent of the electricity produced by a 
nuclear power plant with an average thermal efficiency of 33%, that is, 1 TWh equals 
0.261 Mtoe. 

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Particulates: Terms commonly associated with particulate matter are particulate 
matter with a diameter less than 10 
μm (PM10), total suspended particulate (TSP), 
primary particulate and secondary particulate. PM10 in the atmosphere can result 
from direct particulate emissions (primary PM10) or from emissions of gaseous 
particulate precursors that are partly transformed into particles by chemical reactions 
in the atmosphere (secondary PM10). TSP consists of matter emitted from sources in 
solid, liquid and vapour forms, but existing in the ambient air as particulate solids or 
liquids. 
Petroleum products comprise refinery gas, ethane, liquefied petroleum gas (LPG), 
aviation gasoline, motor gasoline, jet fuels, kerosene, gas/diesel oil, heavy fuel oil, 
naphtha, white spirit, lubricants, bitumen, paraffin waxes, petroleum coke and other 
petroleum products. 
Purchasing power parities (PPP) are the rates of currency conversion that equalize 
the purchasing power of different currencies. A given sum of money, when converted 
into different currencies at the PPP rates, buys the same basket of goods and services 
in all countries. In other words, PPPs are the rates of currency conversion that 
eliminate the differences in price levels between different countries.