|
Lignite and peat |
|
|
Lignite |
|
|
Peat |
|
|
Coke |
|
|
Gaseous fuels |
|
|
Coal gas, mains gas or similar gases |
|
|
Coal gas or similar gases |
|
|
Mains gas |
|
|
Propane and butane |
|
|
Propane gas |
|