World Energy Assessment  Energy and the Challenge of Sustainability  Overview (UNDESA  UNDP  WEA  WEC, 2000, 42 p.) 
World Energy Assessment Overview 
To: 
Terajoule 
Gigacalorie 
Megatonne oil (equiv) 
Million British thermal units 
Gigawatthour 
From: 
Multiply by: 
  

Terajoule (TJ) 
1 
238.8 
2.388 x 10^{5} 
947.8 
0.2778 
Megatonne oil (equiv) (Mtoe) 
4.1868 x 10^{4} 
107 
1 
3.968 x10^{7} 
11,630 
Million British thermal units (Mbtu) 
1.0551 x 10^{3} 
0.252 
2.52 x 10^{8} 
1 
2.931 x 10^{4} 
Gigawatthour (GWh) 
3.6 
860 
8.6 x 10^{5} 
3,412 
1 
* IEA figures. Additional conversion figures available at http://www.iea.org/stat.htm
TABLE A 2. UNIT PREFIXES
k 
kilo(10^{3}) 
M 
mega(10^{6}) 
G 
giga(10^{9}) 
T 
tera (1012) 
P 
peta (1015)) 
E 
exa (10^{18}) 
TABLE A 3. ASSUMED EFFICIENCY IN ELECTRICITY GENERATION (FOR CALCULATING PRIMARY ENERGY)
Type of power 
Assumed efficiency 
Nuclear power 
.33 
Hydroelectric 
1.00 
Wind and solar 
1.00 
Geothermal 
.10 
TABLE A 4. ABBREVIATIONS
CO_{2} 
Carbon dioxide 
H_{2} 
Hydrogen 
kWh 
Kilo Watt hour 
GWe 
Giga Watt electricity 
GWth 
Giga Watt thermal 
MWe 
Mega Watt electricity 
TWh 
Tera Watt hour 
GJ 
Giga joule 
PJ 
Peta joule 