At present 40 pellet plants are operating in Canada, 19 of these plants are in BC scattered throughout the interior along the CN rail line. Prince George region has become a hub of wood pellet plants using mainly pine and Douglas fir as raw material [1] . Efforts are underway to use other soft wood variety like cedar, spruce and Hemlock. Pine is the preferred feedstock because of its abundant resin and easy to grind and dry. But the available pine for making wood products has diminished lately due to the destruction by Mountain Pine Beetle [2] . Pellet industry depends on the availability of mill residues from lumber operations.

Because of the low value of pellets compared to lumber, it is expensive for the pellet industry to harvest wood from the forest and trees, grind and transport that to the pellet plant. To alleviate this problem, new pellet plants are developed in vicinity of milling operations that may be far away from export ports. The transport cost for pellets becomes prohibitive. Wood except bark has a low ash content and is desired as fuel in boilers. Ag feedstock on the other hand is widely available but is not desirable for combustion in small scale stoves because of high ash and chlorine content. Crop residue is used in large co-firing with coal for power production.

In Canada around 90 million tonnes of grains are produced half of which are made up of corn and wheat [3] . The ratio of non-grain biomass to grain mass is assumed to be about 1 to 1. Not all biomass is harvestable. A fraction of biomass must be kept on the ground for soil conservation and fertility purposes. The amount depends on the yield of crop. In low yield not much biomass may be available for removal. We may assume that overall 20% of the biomass may be available and that amounts to 9 - 10 million tonnes of biomass can be harvested in Canada. The challenge is collection of these biomasses, and transports it to the end users.

Despite the abundance of lignocellulosic residues in Canada, they do not currently contribute to the production of biofuel in Canada and their use for bioenergy is limited to a sporadic non-commercial application. A primary barrier is a low and inconsistent quality and inefficient logistics of lignocellulosic residues, a pain point that was deeply felt by the cellulosic ethanol pioneers in the United States, resulted in the slowdown/shutdown of these facilities [4] . One of the lessons learned from these projects is that using straw bales directly as a feedstock in commercial biofuel projects is very challenging and inefficient. Turning bulky biomass with diverse properties to a uniform format, predictable properties and logistically advantageous pellets present a solution. Determining the cost of making pellets plus the logistics costs is one of the goals of this research.

The objective of this research is to analyze a possible solution to the complex handling of ag biomass [5] . The paper discusses steps in harvesting, collection, storage and densification of ag biomass and supply of biomass to the point of its use. To this end the entire supply chain for ag biomass is divided into three distinct sub-activities: 1) baling and transferring bales to the farm yard during the harvest season, preferably the bales will be stored under cover; 2) crushing and grinding bales and pressing biomass to make pellets, and storing pellets in hopper bottom bins during the year, and 3) trucking pellets to a central elevators for bulk storage and shipping pellets to destinations by using rail infrastructure. Pelletization requires experience and skills in operating pellet mill equipment that may not be available at the farmstead. A custom operator may engage in pelletization using mobile equipment. This research estimates costs and CO₂ emissions associated with the proposed supply chain.

The Agriculture and Agri-Food’s Biomass Inventory Mapping and Analysis Tool (BIMAT) provides internet-based GIS functionality to query and visualize biomass inventory data in Canada [6] . The data consists of crop locations, types, historical yield, and a number of other useful information. The Integrated Biomass Supply Analysis and Logistics (IBSAL) model is a modularized simulation of biomass supply chain that includes biomass collection, storage and transportation. In this study, IBSAL modules are assembled to simulate harvesting of straw, stover, and switchgrass yields [7] . The operations in this study started from combining for grain crop residues followed by baling and ended in stacking bales on the field side. Figure 1 shows a baler producing large square bales from wheat straw. Crop residue is baled and stacked at the corner of the field. The stack size and location usually depend on the grid road, that serves a quarter section 160 acres (~65 ha). Chaining the sequence of harvest operations require training in Agricultural mechanization.

The equation C = a R b Y c was fitted to the BIMAT data on yield Y and rate of biomass recovery R to estimate constants a, b, and c for cost in $/dt (dry tonne), energy input in MJ/dt, and carbon emissions in kg CO₂/dt (Table 1). Variable R is the fraction of above ground biomass removed during harvest and Y is the yield defined as biomass above ground (dt/ha). The farm gate cost for the stacked bales ranged from $20 per dt for high yielding regions of southwest Edmonton and Ontario to $27 per dt for the eastern Ottawa region, and $31 per dt for low yielding regions of central Saskatchewan [8] . The costs are validated with published custom rates.

The preprocessing steps consist of breaking up bales to a size that can be fed to hammer mill for grinding bales to a size about 2 mm in order to make pellets as shown in Figure 2.

The equipment required consists of a loader to transfer bales from the stack to bale processor. The bale processor cuts the bale to sizes less than 100 mm. A feed processor that cuts the material to pieces for animal feeding can also be used as shown in Figure 3. The chopped biomass is fed to a hammermill for fine grinding. The hammer mill that is an integral part of the pellet mill shown in Figure 4 grinds the material to around 2 mm. The suspended ground biomass is pushed up to a cyclone to separate the particles from air. The ground material is metered

C = a R b Y c , a, b, and c are tabulated values, R is rate of recovery of biomass (decimal fraction) Y is above ground yield (dry tonne/ha).

to the pellet press to form dense pellets. The pellets (6.3 mm in diameter and 12 mm length) are cooled and sifted and stored in the hopper bottom bin that are used for grain storage on the farm. The pellets remain in the bin until their trucked to the main elevator that is a central storage to hold large volumes of pellets [9] .

Table A1 (Appendix) lists equipment for preparing biomass for preparing and pressing the biomass into pellets, and storing pellets in storage bin. The Table also lists the prices and the year associated with the prices. We used equation 1 to calculate the price in $2019 using an annual rate of inflation at 2.5%.

$ 2019 = $ y e a r ( 1 + 0.025 ) ( 2019 − y e a r ) (1)

For example, the price of bale handler in 2017 at $66,900 is used in Equation (1) to arrive at the price of $70,287 in 2019. The remaining data in Table A1 are conventional values for number of years of life, estimated number of hours per year and rated power for the equipment. Table A2 lists input for the calculation of preprocessing equipment for densification of biomass. For CO₂ emissions per kWh electricity use, we used 0.70 kg between long term USA emission factor at 0.5 kg and a high value of 0.85 kg for Saskatchewan, Canada.

Table A3 lists output of calculations for emissions and the unit cost of producing pellets on the farm. To calculate cost per hour, we divide the calculated $/h by t/h for each unit operation and then multiplied by the tonnage of the pellet press. The pellet press had the lowest throughput (1.2 t/h) and the lowest throughput determines the overall throughput of the entire system. The total cost of producing pellets and placing pellets in storage on the farm was $42.06/h and CO₂ emissions were 146.3 kg/hr. These values divided by the overall throughput of the system yielded cost and emissions per unit mass. The final $35.05 is close to $31.98 that Ref [10] obtained from field testing of a small scale pelletization process.

In terms of generalized equation to calculate cost as a function of initial price and throughput of the pellet press, we developed the following equation for cost of pelletization vs. throughput and initial purchase price by running IBSAL form a range of scenarios.

C p = 0.3 × 10 − 4 P i + 40.58 Y (2)

Cp is the cost of pelletization in $/dt, Pi is the initial price of pellet press (excluding axillary equipment). Y is the throughput of the press mill in dt/h. We should caution against generalization of Equation (2). The equation is only applicable for a narrow range of throughput and the initial price of the pellet mill used in this example.

We applied engineering economics to calculate the cost of transporting biomass from farm to the central storage (hub) ( Table A4). We selected three size trucks, small (29.5 m³ truck box, 185 kW engine), medium (44 m³ truck box, 222 kW engine), and large (85.2 m³ truck box, 259 kW engine) capacity and power. The sizes and prices were taken from Doepker trailer (Figure 5). The prices were adjusted to 2019 by applying a rate of inflation (2.5% per year). Values for years of life, hours of work per year and kilometers driven in a year were within the range of expected operation of the transport equipment.

To calculate fixed and operating costs, we used ASABE Standards EP496 and D497 costing method. The methods were outlined in a special report prepared for AAFC [8] . Table A5 lists the input values to the engineering economic equations. We assumed annual 6% for interest rate and annual 2.5% for rate of inflation.

The rate of insurance, housing, and taxes on annual basis was 2% of the purchase price of equipment. ASABE specifies the conversion of engine power to average hourly fuel consumption (0.223 L/kW engine power), equivalent of carbon dioxide emissions from burning each L of fuel (2.64 kg CO₂/L of fuel). For these calculations we assumed 50 km one way and average speed of 50 km/h. The effective distance travel is 2/3 of the supply radius for a circular supply area with the hub at the center of the circle.

Table A6 lists the output cost and emissions from the three size trucks with the inputs listed in Table A5. The fuel cost is a major cost item, 60% to 66% of the hourly cost of the truck. Fixed costs are a small portion of the total hourly cost of the equipment [11] . Tire cost is another operating cost that must be calculated carefully. For example we may assume a new tire lasts 100,000 km. Each tire may cost $400 to replace. The truck is driven 12,500 km/year. Therefore to replace tires in a 10 wheel truck is calculated by [12]

T i r e $ h = 12500 / 100000 ∗ 10 2560 = 0.20 (3)

Table A6 lists the hourly cost of transport ranges from $90.89 to 117.48 per dt depending on the size of transport equipment. The corresponding CO₂ emission ranges from 108 to 152 kg per dt of biomass mostly depending on the fuel consumption of the transport equipment.

Conventionally, cost of transportation has been calculated using an equation similar to the following [13]

C T r = 7.67 + 0.18 d (4)

C_Tr is $/dt and d is distance travelled (km). Equation (4) has been widely reported in the literature for calculating the cost per tonne given a distance. The model is described as fixed cost $7.67/dt for loading and unloading; the coefficient $0.18 accounts for $ per dt per km. The problem with Equation (4) is that it does not consider variable fuel prices as well as the load carrying volume of the truck and fuel surcharges.

We further conducted a detailed engineering economics on three size of commercial trucks for handling pellets and included fuel use and its price. The following empirical equation described the data best,

C T r = ( 15.24 G + 4.08 ) L n ( Q ) − 9.48 G + 17.84 (5)

C is transport cost ($/h), G is fuel price ($/L) and Q is volume load capacity of the truck (m³). The travel time for the truck is calculated as,

t = 2 d V (6)

t is travel time (h), d is the distance (km) one way, and V is the average speed (km/h). For a circle around the supply region, the distance D is equal to 2/3R, where R is the radius of the supply region. The dry tonne capacity of the truck is calculated from volume and load density,

w = ρ Q (7)

w is the volume mass capacity of the truck (dt), Q is load volume of the truck (m³), and ρ is the density of the load (dt/m³). The cost $/dt is then calculated from the following equation,

C T r = [ C ] [ t ] W (8)

C_Tr is ($/dt) for transport.

Combining Equations (5)-(8) results in a single equation to calculate $/dt for transport

C T r = 2 d [ ( 15.24 G + 4.08 ) L n ( Q ) − 9.48 G + 17.84 ] ρ V Q (9)

For pellets with a density of 0.65 dt/m³ and a distance of 2/3 of 50 km, and average speed of 50 km/h, Equation (9) reduces to

C T r = 1 Q [ ( 31.24 G + 8.32 ) L n ( Q ) − 19.43 G + 36.57 ] (10)

C_Tr is unit transport cost ($/dt), Q is the load volume capacity of the truck, G is fuel price ($/L). For a truck 29.5 m³ truck volume, and $1.35/L for the price of diesel, the transport cost is calculated to be $6.14/dt.

Our major assumption for this project is that the biomass takes a logistical route similar to grain. The material is transported by grain-type trucks shown in Figure 5 to elevators (the hub) where the pellets are stored in silos. The Canadian Grain Commission published tariffs for elevating grain, storing, and out loading the grain. Table A7 lists the average cost of elevation ranges between $13.90/t to $17.44/t. Note that t is tonne representing the mass of grain as is with respect to the standard moisture content. The standard moisture content ranges from 9% for canola to 15.5% for corn. Most of the small grain cereals are designated at a standard moisture content of 14%, all in wet mass basis.

The average cost increases to $22.3/t. for other grain and grain screening category. The cost for elevating corn appears to be cheaper than other crops. The minimum cost of storage is recorded at $8/t to a maximum of $40/t for grains and $66/t for grain screening. The reason for this large variation among different grains and elevators is not known to the author at this time. The cost of storage per day ranges from $0.09/t to $0.12/t. The variability among primary elevators for storage ranges from $0.02/t to $0.20/t per day. The variability in storage cost is higher than the variability in elevation.

Currently there are 206 primary grain elevators in Saskatchewan enumerated in Figure 6 based on their capacity. A handful of these elevators are designated as processing elevators engaged in processing activities like flour milling and grain cleaning. Primary elevators are mainly engaged in receiving grain from grain trucks, loading grain into the silos, storing grain for a period, and loading the grain into the rail cars when an order for transport comes in. The elevators may be equipped with grain dryers and grain screening facilities. The capacity of primary elevators ranges from few hundred tonnes to the largest in Moosejaw (Vittera Inc.) at 160,670 t. Roughly 55% of the elevators have a capacity less than 20,000 t, 43% have a capacity between 20,000 to 40,000 t.

Grains is dispatched from elevators to in-land or seaport destinations by using rail cars. The two major railway companies CN and CP cover the entire country

and is connected to the US railway system as is shown in Figure 7. Both companies carry grains from inland terminals to the ports in Eastern, Central, and Western Canada. CN has current presence in the U.S. and CP will be active in the U.S. as well. At the present CN Railways is the sole carrier of wood pellets. The gravity flow of pellets allows pellets to be loaded into rail cars similar to those used for carrying grain. A railcar typically holds 85 to 100 t. In Canada, the average load is about 80 t/carload [14] . Average number of rail cars in a freight train (sometimes called unit train) ranges from 80 to 108 cars. Figure 8 shows a unit train is standing by a modern elevator. Average length of the haul for class 1

trains in Canada (CP and CN) was 1500 km in 2016 while the average haul for short line ranged from 128 to 306 km. The bottom of a car consists of three or more divided hoppers with doors hinged lengthwise of car and dumping between rails when unloading.

We developed the following generalize equation to describe the transport of pellets from an elevator to a destination,

C R = 4.50 + 0.0336 d (11)

C_R is $/dt, d is distance travelled in km. We included the BC surtax in anticipation that such a tax will be instituted nationally under the Clean Fuel Standards. Using a distance of 200 km will make the cost of transporting pellets at $4.57 d/t.

The analysis in this research offers a pathway for commercialization of ag pellets in Canada. One of the major hurdles in supplying ag pellets to market place is the lack of infrastructure for post production handling of pellets. In this article, we demonstrated that it would be feasible to view handling of pellets similar to handling of grains. Once pellets are made at the farmstead, the pellets are stored in hopper bottom bins. The delivery of biomass from the farm to a point of use will take a route similar to that of the grain.

Table 2 and Table 3 summarize the costs and GHG emissions associated with handling of biomass bales, pelletization, small and large scale storage and transport. The costs do not include drying that would be a major expense and source of emissions. Small grains not including corn grown on the Prairies are dry at

the time of harvest [15] . Drying of straw may not be needed for these locations.

A few unknowns need to be worked out to realize the proposed pathway from making ag pellets and transporting the pellets to market. A demand is created for ag pellets, the quality of pellet with respect to durability and ash content meets the acceptable standards, there must be adequate storage capacity both on the farm and at the elevator to hold the additional volumes of pellets, the rail companies like CN and CP are willing to enter in transporting ag pellets similar to wood pellets.

The authors acknowledge the financial support received from Agriculture & Agri-Food Canada’s Agri-Science Partnership Program. The BioFuel Net Canada manages the Program under the Biomass Cluster Canada.

The authors declare no conflicts of interest regarding the publication of this paper.

Sokhansanj, S., Ebadian, M., Rezaei, H. and Yazdanpanah, F. (2023) The Logistics of Production and Supply of Ag Pellets for Industrial Applications in Canada. Journal of Sustainable Bioenergy Systems, 13, 40-55. https://doi.org/10.4236/jsbs.2023.131003

Source: https://www.grainscanada.gc.ca/en/grain-research/statistics/elevator-charge-summaries/.