Alcohols: methanol, etanol, butilic ecc.
|Low cost||Combustion products: H2O and CO2|
|Natural Gas (metane) e LPG (propane, buthane)||Low cost.||Combustion products: H2O and CO2|
|Hydrogen||Cost from nothing to low, (depending on the generating method)||Combustion products only and esclusively water (H2O)|
|Waste (for instance burnt in an incinerator)||Nil||The combustion products are that generated in any case by the incinerator.|
|Paper, wood and derivatives||Low or nil||Recyclable cinders for agricolture.|
|Solar energy||Nil||No combustion, no product.|