What is bioenergy?

Bioenergy is energy derived from biofuels, which is defined according to Swedish Standards as "fuels where biomass or peat is the original material. The fuel can have passed through chemical processes or transformation or other use". Biomass is according to the same Standrads "material with biological origin that has not, or only to a modest extent, been chemically transformed".

More than 28% of the total use of energy in Sweden 2008 came from biomass.
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Biofuels can be categorised into different sub-groups. The most common is to categorise on the basis of origin:

Wood fuels is made up of wood raw material from the forest that has not gone through any chemical process.  This includes felling residues - branches and tops - that are left over at extractions of timber and wood for the pulp industry. At saw mills and in paper and pulp industries, shavings and bark become rest products that can also be used as a fuel, either directly or densified as pellets and briquettes. Recycled wood also belong to the group of wood fuels. 

Spent liquors is another bi-product of large volumes within the pulp industry. Spent liquors are produced when wood chips are boiled into paper pulp. It consists of a blend of lignin and chemicals. When spent liquors are combusted in soda recovery boilers, energy and electricity is extracted and process chemicals can be recycled. New and more efficient technologies for gasification of spent liquors are new being developed where transport biofuels also can be produced in the process.

Agricultural fuels are cultivated crops or waste products from crop production. Energy forests (Salix), energy grass (i.e. Reed Canary Grass), energy hemp, straw, grains, corn, sugar beets, rape seed etc are some examples. Salix is used as chips in district heating or CHP plants, energy grass and hemp can be made into briquettes, straw is combusted for heat production, but could also be pelletised with new technologies.  Grains such as wheat and barley are used for fuel ethanol production through fermentation, oats is combusted for heating. Rape seed oil is used to produce biodiesel (RME) but can also be combusted for heating. Ley crops are used for biogas production through digestion, mostly together with manure or organic waste from slaughteries and food industry.

Biofuels from waste. Waste combustion generates energy and electricity. Technologies for waste combustion are today very clean and combustion is the most efficient way to extract energy from waste. Digestion of organic waste and sewage sludge as well as landfill gas can also be referred to as biofuels from waste.

Peat fuel is produced from peat, which is a biological material that is not fully decomposed and that can be found in bogs and in ditched peat lands. In Sweden peat is counted as a slowly renewable fuel. When co-fired with wood fuels, peat improves boiler efficiency and operational security.

Biofuels can also be categorised according to whether they are

• solid
  
• liquid  
• gaseous  
  

• heating
• electricity
  
• transports