Category Archives: Biomass Basics



Woody biomass has been used for hundreds of years as a fuel source, primarily as solid wood being burned in a fireplace or stove. For much of the 20th century, excessive waste residuals from forest industry facilities such as sawmills, were disposed of by burning in piles or `tee-pee’ burners. Even today, most logging residuals are unused and are disposed of by burning in slash piles. In the mid part of the 20th century, industry started to use their woodwaste as a fuel source for process heat and electricity (cogeneration / combined heat and power).  Also, wood pellets started to be used as a domestic fuel in homes, primarily in Europe.

Climate change and global warming have become big topics in the last 20 years, and most scientists believe that mankind is a significant contributor to global warming, particularly through the use of fossil fuels. Recently, progressive governments committed to reducing their green-house gases (GhG’s) and are promoting and funding considerable research into finding sustainable, low-carbon energy sources. Governments have mandated the closure of coal-fired power plants and are looking for alternative fuels. Consequently in the last decade, the world `discovered’ woody biomass and is focusing on its use as a sustainable, low-carbon fuel or feedstock for bio-chemicals. Continue reading →


An edited version of this article appeared in the November / December 2011 issue of Canadian Biomass magazine.

Paul Janzé, Advanced Biomass Consulting Inc.


This article has been the most popular and has received the most attention since I wrote it in 2011. I’ve done a couple of rock removal studies since then and decided the article needed updating with new information.

Reject Rock

The upsurge of interest in biomass-fired power plants in the past few years is accompanied by a corresponding increase of interest in methods for removing non-combustible, non-organics such as rocks, stones, sand and grit from woody biomass. Rock contaminated woody biomass has long been a problem, and many ways have been attempted in trying to deal with it. The methods are varied, usually depending upon the end-use to which the biomass is being put. There are some specific methods that are very successful; others more a measure of how best to accommodate the problem.

Following is a brief description of the problems, solutions and accommodations that various biomass processing industries utilize when dealing with rocks and other non-organic contaminants in their woody biomass. Continue reading →



Most raw materials for plants that process woody biomass are delivered in bulk trucks and some are delivered by railcar. This article concerns biomass delivery by truck and the systems available for unloading the trucks.

Chip Truck Dumper
Chip Truck Dumper

Residual chips, shavings, and sawdust from sawmills are delivered primarily by truck to pulpmills, pellet plants, and panelboard plants. Woodwaste (hog fuel) from sawmills and other raw log processors is delivered by truck to biomass-fired energy systems and cogeneration plants. Wood pellets are delivered by truck and by railcar and are loaded onto ships or delivered direct to biomass-fired power plants.

Delivery by Truck

There are many different types and sizes of trucks used depending upon the material being handled, the weather conditions, the unloading facilities available, distances traveled, the types of truck available, road conditions, the most economical transport method, road weight allowances, required throughput capacity, etc. There are generally two types of trucks used: self unloading and non-self unloading trucks. Continue reading →


Paul Janzé – Advanced Biomass Consulting Inc.

For many reasons, people need to know how much material is present in a biomass storage pile. Hog Fuel Storage, 2Accurate volume measurement is relatively easy, but to determine the amount of dry fibre actually present, the compacted density and moisture content are required. In fact, the greatest number of queries I receive at this website are with regard to biomass pile density and compaction. This is because compaction is the most difficult pile parameter to determine with any consistent accuracy.

Biomass is highly compressible both through artificial and natural means. Every material is different and every pile is different.  The amount of compaction depends upon the species, the form of the material, the relative amounts of bark, wood and foliage present, the grind size, particle size distribution, moisture content, weather conditions, the shape of the pile, how the pile is constructed, how long it has been sitting, the amount of decomposition, the amount of contamination with dirt, grit or stones, etc. So, it is just an educated guess as to how much compaction there will be in any one pile. Continue reading →


Author: Paul Janzé, Advanced Biomass Consulting Inc.

Sliver Screen2The disc screen is a simple piece of equipment that is ideal for, and commonly used for screening woody biomass. It consists of a series of driven shaft assemblies mounted in a frame.  Each rotor shaft assembly has profiled discs mounted at regular spacings. The discs from one shaft interleaf with those on the adjacent shafts, creating open areas between the discs and the shafts.

Incoming material is fed onto one end of the screen.  The shaft assemblies rotate, and the discs agitate the material. Pieces of material that are smaller than the spacing between the discs and shaft assemblies fall through the screen.  The pieces that are larger than the openings are conveyed along the top of the discs and pass over the end of the screen.

Disc screens are particularly useful for screening biomass for the following reasons: Continue reading →


Author: Paul Janzé, Advanced Biomass Consulting Inc.

Harmac Scalping Screen, 1
Disc Screen

Because of the wide variation in material characteristics, selecting the appropriate screen for woody biomass is not as straight forward as it is for other materials.  This article is intended to provide general screen selection information based on the author’s experience as to what types of screens work best with different forms of woody biomass.

I’ve said this many times before and I will repeat it once again.  “Biomass is not an easy material to handle. It appears in a myriad of species, forms and sizes; it knits together, doesn’t flow well, consolidates and packs easily. It can have a wide range of moisture contents, basic and bulk densities and calorific values. It will freeze; is very dusty, catches fire easily and is self-combustible. It can contain all manner of contaminants.  On the other hand, wood pellets are uniform in size and moisture content, are very free flowing, but are quite fragile and easily degrade and require special handling.” Continue reading →



mill-1Fires have always been a problem in wood processing plants, particularly in those that handle dry material, including wood finishing plants, panelboard plants and wood pellet facilities; less so in sawmills. Historically, most sawmills in BC were accustomed to processing `green’ wood with moisture contents of 40 – 55%, wet basis.  While not unknown, fires were not a common experience with such wet wood, and explosions were unheard of. So, the fires and explosions in northern BC in 2011 and 2012, which resulted in the total destruction of two large sawmills, multiple deaths and injuries, is great cause for concern.  Everyone is asking, “What happened?” The relevant safety authorities are currently investigating both incidents and at this point in time, firm causes have yet to be identified. Continue reading →



With the current emphasis on biomass usage as a `green’ fuel for energy plants, it has become apparent that there is a need for understanding the requirements for storing biomass.  Woody biomass, called `hog fuel’, has long been utilized as a fuel in cogeneration plants at pulp and paper mills, where it was traditionally a waste product from the processing of clean white wood chips used to make pulp.  While many practical lessons have been learned about what is appropriate for hog fuel storage, generally little documented study has been directed at storage practices, primarily due to its abundance and historical status as a waste product with next to zero value.

However, hog fuel is the basic feedstock for biomass-fired power plants and is becoming a hot commodity and it is the single biggest on-going cost item for energy plants.  How it is handled has an effect on quality, so a greater understanding of hog fuel storage requirements is required. Continue reading →


Where any bulk, raw resource is used in an industrial process, there is a requirement to track both usage and inventory.  And with the increased movement to utilizing biomass as a fuel source, more companies are discovering the difficulty in accurately measuring biomass inventory.

The traditional method of determining inventory has been to measure the volume of a pile and from that back-calculate the tonnage.  However, accurately determining the amount of fibre in biomass piles has long been problematic and even today with accurate measuring devices, fibre measurement doesn’t have an easy solution.

Pulp and paper mills everywhere have struggled with this problem for years.  One year they will have to write-off wood chip inventory that appears to have disappeared; the next year they will have too much inventory.  Other facilities that utilize biomass have similar inventory assessment problems.

Volume Measurement

Pile size and volume is measured by surveying and years ago the lack of accuracy was accepted and used to explain inventory variances.  With current measuring technology, the volume measurement accuracy has greatly improved and yet the estimate of actual fibre remaining in the pile is still not very accurate.  Generally, the problem lies with not knowing the amount of compaction and the consequent density inside the pile.  Without this knowledge, back-calculating tonnage from a volume measurement is quite `hit and miss’. Continue reading →

Handling Pellets – Things to Consider

An edited version of this article was published under the title “Handle with care” as a feature article in the UK “Bioenergy Insight” magazine, Volume 1, Issue 1, October 2010.

It’s fair to say that Europe is a decade ahead of the rest of the world when it comes to ‘green’ issues, and no more so than in the area of renewable energy sources, particularly utilizing woody biomass as a source of fuel.

Europe is an interesting case, as on one hand, it is the world leader on green issues and has vigorously promoted biomass as an alternative fuel; and on the other hand, it is far from sufficient sources of woody biomass.

As a contrast, Canada has a tremendous amount of woody biomass. And, for decades residual wastewood has been well-utilized as a fuel source for industrial plants.  However, there is little incentive in Canada to utilize standing forests for fuel as we have such a small population, and an abundant supply of low-cost energy, for example, hydro power in BC, oil in Alberta, nuclear power in Ontario.

Likewise, Russia and the southeastern USA have large amounts of wood fibre available that can be used for energy production. Continue reading →