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GCB Bioenergy

Cover image for Vol. 9 Issue 9

Edited By: Steve Long

Impact Factor: 4.655

ISI Journal Citation Reports © Ranking: 2016: 2/83 (Agronomy); 15/92 (Energy & Fuels)

Online ISSN: 1757-1707

Associated Title(s): Global Change Biology

How will Torrefaction Influence Sustainability?

How will Torrefaction Influence Sustainability?

It is expected that the use of biomass in energy generation by the European Union (EU) will increase significantly as they attempt to achieve their renewable energy goals. One type of biomass used in Europe for energy generation is wood pellets, which are manufactured from compressed sawdust and shavings from the sawmilling industry. The pellets can replace, or be co-fired with, coal in existing power plants. Pellets have the advantages of being uniform for ease of handling with existing infrastructure, dense for ease of transport, low in moisture to produce more energy, and uniform in composition for ease of blending.

Although wood pellet production is expected to increase over the next ten years, the supply is not expected to meet the growing demand of the energy industry. Europe’s biomass needs could be met by using forest residues such as tree bark, and stump wood, which are abundant. However, these materials do not have the same advantages as wood pellets. They have low energy density and high water content, poor storage ability and require special handling, and are therefore not compatible with existing power plants.

Agar and Wihersaari propose that the fuel and handling characteristics of forest residues could be improved by torrefaction; a pretreatment process of heating biomass in the absence of oxygen which causes water and hemicellulose to be released resulting in increased energy density. Conventional wood pellets could also benefit from pretreatment because they are vulnerable to moisture. Previous research has shown that after torrefaction biomass has a reduced tendency to absorb moisture, making it easier to store.

Agar, D. and Wihersaari, M. (2011), Torrefaction technology for solid fuel production. GCB Bioenergy. doi: 10.1111/j.1757-1707.2011.01141.x Read this paper.

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