Biomass is plant-based material used as fuel to produce heat or electricity. Examples are wood and wood residues, energy crops, agricultural residues, and waste from industry, farms and households. Since biomass can be used as a fuel directly, some people use the words biomass and biofuel interchangeably. Others subsume one term under the other. Government authorities in the US and the EU define biofuel as a liquid or gaseous fuel, used for transportation. The European Union's Joint Research Centre use the concept solid biofuel and define it as raw or processed organic matter of biological origin used for energy, for instance firewood, wood chips and wood pellets. In 2019, 57 EJ of energy were produced from biomass, compared to 190 EJ from crude oil, 168 EJ from coal, 144 EJ from natural gas, 30 EJ from nuclear, 15 EJ from hydro and 13 EJ from wind, solar and geothermal combined.