Important Terms from A to Z
Biofuels (Biogenic Solid Fuels) to Generate Heat and/or Electricity
Some biomass products are “biofuels,” a term that mostly refers to biogenic solid fuels. Please refer to the term bioenergy in this glossary for an explanation of the difference between solid, liquid and gaseous bioenergy.
Biofuels/biogenic solid fuels are defined as recent fuels of organic origin that are in solid form when they are used to generate energy, i.e. burned for heat and/or electricity. Biogenic solid fuels are differentiated into “residues/by-products” and “energy crops”:
- By-products and residues of woody biomass include residual wood from forestry, scrap wood from landscape maintenance and industry, and sawmill waste, which are also used for the production of the biofuels wood pellets and wood briquettes. Of course the direct use of this wood in the form of firewood/logs or wood chips (roughly chopped wood) is one of the best known forms of biofuel. Beyond this, by-products/residues also include herbaceous biomass (such as straw, roadside grass clippings) and other biomass (e.g. low-grade crops, residues from pressing).
- Energy plants that form woody biomass (wood from short-rotation plantations – SRP) and herbaceous biomass (energy grasses, cereal plants) are mainly used for the production of biofuels like pellets, or directly used as an energy source without prior processing. However, it is considerably more expensive and usually not (yet) economical to produce higher-quality pellets according to ISO 17225-2 (class A1), which also meet the fuel-quality requirements of smaller systems/furnaces, from energy crops (from SRP).
Biogenic solid fuels are therefore primarily used as an energy source because they are environmentally friendly, sustainable, regionally available and inexpensive – this is especially true for by-products/residues, which mainly are waste products from landscape maintenance and industry.
Biofuels represent stored solar energy, and solar energy is the largest source of energy on earth. This also explains the great importance of biomass as an energy source in the field of renewable energy, and the steadily increasing demand for biogenic solid fuels for producing heat and electricity across all applications from industry and municipal/community institutions to private households.
Depending on the type of plant, industrial consumers can use various forms of biofuels in large biomass heating (power) plants to generate heat and/or electricity. Usually, these large plants primarily process or burn woody (not herbaceous) biomass, including wood chips and industrial pellets. The industrial use of biofuels is sometimes also carried out in parallel with the use of the energy sources gas or oil – known as “co-firing” – which makes it possible to use modern plant technology without problems, and serves mainly to reduce CO2 emissions as well as fuel costs.
Urban/municipal and private consumers with modern heating systems of up to 100 kW usually require higher-quality biofuels than industry. These are primarily wood pellets and wood chips, and in private households also logs and wood briquettes. The properties of standardized biogenic solid fuels are comprehensively regulated in the European ISO 17225 standard and in many places in Europe are supplemented or implemented by national or international certification programs, such as ENplus and DINplus for wood pellets.
Status: December 2015
All information subject to change. Errors and omissions excepted.