Biofuels | Solid Biofuels

Pretreatment, transport and handling are often the most unpredictable and costly portions of bioenergy operations. One way to overcome some of these limitations is to transform biomass into solid pellets.

Pellet manufacturers take byproducts (like wood waste) and refine them into pellets that are uniform in size (typically ¼ inch or 6 mm), shape, moisture, density and energy content. The moisture content of pellets is substantially lower (4% to 8% water, compared to 20% to 60% in raw biomass). Less moisture means a higher British Thermal Unit BTU value and easier handling, especially in freezing situations with green raw biomass materials. Furthermore, the density of pellet fuel is substantially higher than raw biomass (40 lbs. per cubic foot vs. 10–25 lbs. per cubic foot in raw form). Thus, more fuel can be transported in a given truck space, and pellets are more easily handled. Owing to its consistency, combustion of pelletized fuel produces a fraction of the particulate emissions typical of raw biomass.

There are a number of issues with current pellet production techniques that need to be addressed. Current pellet production techniques result in pellets that are relatively fragile, subject to gassing, and decompose rapidly in the presence of water. Research is necessary to address these shortcomings.

We are collaborating with the Wood Pellet Association of Canada  and universities to research pellet production from a variety of feedstocks, as well as to research related issues including advanced processes for pelletizing (e.g. steam explosion and torrefaction) where the pressure required to form pellets is reduced, thereby considerably reducing energy consumption.

We are also providing technical support to Canadian companies involved in researching “biochar,” another solid biofuel. Biochar is charcoal produced from biomass, usually via low-temperature pyrolysis. Biochar can also be a byproduct from fast pyrolysis processes. Biochar can be used directly as a fuel or in a pelletized form, but it can also be readily converted to activated carbon or used as a soil amendment. There is evidence that low-temperature biochar produces robust growth in plants.