Torrefaction of biomass and 'biocoal' technologies

Overview

Torrefaction is a thermochemical process typically at 200-350 °C in the absence of oxygen, at atmopsheric pressure with low particle heating rates and a reactor time of one hour. The process causes biomass to partly decompose, creating torrefied biomass or char, also referred to as 'biocoal'. Biocoal has a higher energy content per unit volume, and torrefaction followed by pelletisation at the harvest sites facilitates transport over longer distances. It also avoids problems associated with decomposition of biomass during storage. Hence the benefits of torrefaction may outweigh the additional cost in many cases.

An overview of torrefaction technology and market potential is provided in the report:
Wood torrefaction – market prospects and integration with the forest and energy industry
Carl Wilén, Kai Sipilä, Sanna Tuomi, Ilkka Hiltunen & Christian Lindfors, VTT, 2014

EC Projects on Torrefaction and Biocoal

The NEWAPP "New technological applications for wet biomass waste stream products" project, supported by FP7, aims to develop hydrothermal carbonization HTC processes to convert wet biomass into biocoal at 'moderate' temperatures and pressures in the presence of water. The process also yields a water phase rich in plant nutrients.

FP7 Project SECTOR - Production of Solid Sustainable Energy Carriers from Biomass by Means of Torrefaction started in 2012 and runs for 42 months. The final project meeting is in Leipzig on 6-7 May 2015.

Torrefaction and 'biocoal' R&D and commercial demos/plants

In February 2014, Topell Energy, Essent, Nuon and GDF SUEZ, and ECN successfully completed a large-scale cofiring of torrified pellets at the Amer power plant, Geertruidenberg, Netherlands. See Commercial-scale biomass torrefaction demonstration. In November 2015, Blackwood Technology, Netherlands, acquired the world leading torrefaction technology and the team from Topell Energy.

Torrefaction is also being developed in the US. For example, in May 2012 Vega Biofuels (VB) announced plans to build a new bio-coal manufacturing facility in Georgia, US. Timber waste will be used as the feedstock. Zilkha Biomass Energy LLC and Valmet Corp. signed an agreement in early 2014 to develop steam exploded black pellets which can be used directly in coal-fired power stations. Zilkha is also providing technology to Thermogen in the US.

In Canada, Diacarbon Energy Inc is developing a pilot torrefaction bioreactor with support from the British Columbia Bioenergy Network. Solvay and New Biomass Energy are further developing an industrial-scale torrefaction operation in Quitman, US and aim to triple production to 250,00 tons by end of 2014.