Subject
petroleum
electricity
17
energy statistics
17
gas
17
mining
17
petrochemical industry
17
energy planning
13
environmental protection
12
petrochemistry
12
energy economy
5
coal
3
energy
2
natural gas
2
nuclear energy
2
renewable energy
2
energy source
1
energy supply
1
geography
1
policy
1
politics
1
resource
1
spatial analysis
1
support
1