page_title: Biomass
section_title: Thermal conversions
hierarchical_section_title: Biomass / Biomass conversion / Thermal conversions
caption_attribution_description: English: Stacks and stacks of bales. Now that straw burning is taboo and that keeping cattle is becoming focused into the West, it is hard to imagine where all this straw gets used. If kept dry, perhaps it could be used in a biomass boiler or power station - or would that involve too many straw miles?
context_page_description: Biomass is plant or animal material used for energy production, or in various industrial processes as raw substance for a range of products. It can be purposely grown energy crops, wood or forest residues, waste from food crops, horticulture, food processing, animal farming, or human waste from sewage plants.
  Burning plant-derived biomass releases CO₂, but it has still been classified as a renewable energy source in the EU and UN legal frameworks because photosynthesis cycles the CO₂ back into new crops. In some cases, this recycling of CO₂ from plants to atmosphere and back into plants can even be CO₂ negative, as a relatively large portion of the CO₂ is moved to the soil during each cycle.
  Cofiring with biomass has increased in coal power plants, because it makes it possible to release less CO₂ without the cost associated with building new infrastructure. Co-firing is not without issues however, often an upgrade of the biomass is most beneficial. Upgrading to higher grade fuels can be achieved by different methods, broadly classified as thermal, chemical, or biochemical.
context_section_description: Thermal conversion processes use heat as the dominant mechanism to upgrade biomass into a better and more practical fuel. The basic alternatives are torrefaction, pyrolysis, and gasification, these are separated principally by the extent to which the chemical reactions involved are allowed to proceed (mainly controlled by the availability of oxygen and conversion temperature).
  There are other less common, more experimental or proprietary thermal processes that may offer benefits, such as hydrothermal upgrading. Some have been developed for use on high moisture content biomass, including aqueous slurries, and allow them to be converted into more convenient forms.
caption: Straw bales
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