First, sugary and starchy feedstock such as corn must be crushed and combined with water, allowing enzymes to convert this starch into sugar. Digestate is the decomposed substrate, rich in macro- and micro-nutrients and therefore suitable for use as plant fertiliser.įermentation is a biochemical conversion whereby microorganisms, including yeast and bacteria, convert matter into products such as ethanol and liquid transport fuel (biodiesel). Biogas can also be upgraded via purification processes to a biomethane that can be injected into the existing natural gas networks, used as a chemical product and/or vehicle fuel. Biogas can be used in direct combustion to produce heat, but also power if converted within a cogeneration plant or in adapted gas motors. Biogas is a combustible gas consisting of methane, carbon dioxide and small amounts of other gases and trace elements. A wide range of micro-organisms are involved in the anaerobic process which has two main end products: biogas and digestate. Anaerobic digestion and fermentation are the two main conversion pathways used for converting wet biomass feedstock into advanced fuel.Īnaerobic digestion is the microbiological process of decomposition of organic matter, in the absence of oxygen, and is common to many natural environments it is largely applied today in order to produce biogas in airproof reactor tanks, commonly referred to as digesters. anaerobic digestion) and biofuel sectors (eg. As it contains too much moisture to be converted efficiently into energy via a direct combustion process, other conversion pathways and energy outputs have been developed by the biogas (eg. Wet biomass is present in high volume across Europe (manure, agricultural waste and by-products). Gasification is another thermo-chemical conversion that takes place at high temperatures (>800☌), with limited oxygen and/or steam, and converts solid biomass into synthesis gas, known as syngas – which contains carbon and hydrogen and can be used to produce liquid fuels such as biodiesel. Pyrolysis, for instance, is a thermal-chemical conversion that requires a high temperature (>400☌) and little oxygen to convert solid biomass into gas, liquid fuels (pyrolysis oil) and/or biochar. Thanks to advanced technologies, woody biomass can also produce liquid and gaseous fuels. As compared to conventional wood, torrefied wood has very low (>5%) moisture content, is easily grindable and is relatively hydrophobic. Comparable to some extent to coffee torrefaction, this method creates a fuel with unique characteristics. During the torrefaction process, wood is subjected to temperatures of 230☌-300☌ at atmospheric pressure without oxygen.
Thermo-chemical conversions are now used to produce fuel with even higher calorific value, utilising torrefaction or steam explosion technologies. Thanks to densification, the homogenous biomass fuel is easier to transport and can be used in automated biomass installations, such as pellet stoves and boilers.
The heat during compression fuses the lignin in the biomass, naturally binding the biomass together in a new, enhanced shape. This process involves compressing biomass and lowering moisture levels to a range of 8-10%, allowing for an homogenous fuel – either in the form of pellets or briquettes. In general, moisture content in woodchips used for energy generation in municipal or industrial plants ranges between 20-30%.ĭensification is another popular way to transform woody material into an advanced fuel with high calorific value. These operations help transform biomass into homogeneous fuel that is easy to handle, with a higher energy recovery (eg. Logging, grinding, screening and drying operations are mechanical processes for enhancing solid biomass fuels.
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