Torrefied biomass: foresighting report

Torrefaction is a low temperature thermal process applied to biomass materials to modify their properties for further processing. The resulting material can be easily stored, handled and milled and the torrefied material can also be pelletised, bringing its energy density closer to coal. This foresighting study aimed to investigate the business case for pellets from torrefied biomass as a new solid fuel source. The study also highlighted potential opportunities for Scotland in this context.

The methodology consisted of: desk research of relevant reports on the commercialisation of biomass; contributions from Energy Research Centre of the Netherlands (ECN), The University of Aberdeen and Renfrew-based Mitsui Babcock; examples of other torrefied biomass demonstration plants; a discussion of process simulations and economics; and outlines of costs of producing torrefied pellets (TOP) using different feedstocks for operations, collected from literature and industrial contacts.

The report suggests that, because of the potentially huge sustainable supply and physical similarity to coal as a solid fuel, torrefied pellets (TOP) could become the future fuel of choice for space heating and co-firing with coal for power generation, provided the fuel can be produced and delivered at a competitive price. Conceptually, a 20 kilotonnes (kT) per year demo plant would supply the local wood pellet market for residential and commercial heating and provide significant amounts of products for large scale trials in power stations. A combination of forest residues and sawmill co-products would be required to get near the levels of supply required for feedstocks with a moisture content of 50 per cent. An international trade in biomass is already operational: given the high energy density of TOP pellets, it would be sensible to manufacture them in the country of origin of the feedstock and export the pellets. The ability to contract for a significant portion of the continuous supply of suitable feedstock required for the prospective torrefied fuel production plant, at an appropriate price, and over the proposed period of plant operation, will constitute one of the key assets of a biomass-to-energy project.

The report suggests that further de-risking work is required prior to planning the construction of a demonstration plant in Scotland. The report recommends various major actions required over 2007, including: validating the innovative torrefaction reactor developed by ECN, and testing it on local Scottish feedstock, such as spruce residues; confirming the suitability of torrefied pellets for co-firing with coal in power plants, and for boilers in the residential and commercial markets, with a series of trials; identifying one or several suitable locations in Scotland which have adequate supply and logistics; evaluating the commercial potential of this new fuel both at a local and international level and any credits for carbon emission reduction or other pollutants; and bringing together a consortium of interested stakeholders from the forestry industry, engineering companies and energy companies, to identify the benefits of participating in a demo plant. Financial resources required for executing the above actions are currently estimated at about one hundred thousand pounds. ITI Energy proposes to progress and complete these actions in close cooperation with a group of active members in the relevant areas.