The key decision points for the design of a logistics system for a bioenergy plant operating 24/7 year-round are summarized as follows:

1. A complete logistics system is defined as one that begins with the biomass standing in the field and ends with a stream of size-reduced material entering a bioenergy plant for 24/7 operation. Optimizing one unit operation in isolation may increase the cost of an “upstream” or “downstream” operation such that total delivered cost is increased.

2. Herbaceous biomass is harvested only part of the year, thus storage is always a part of the logistics system. A cost effective logistics system provides for efficient flow of material into, and out of, storage.

3. Just-in-time (JIT) delivery of feedstock provides for a minimum at-plant storage cost and is preferred by plant designers. Since JIT delivery is not practical for typical biomass logistics systems, there is always a cost trade-off between the size of at — plant storage and the other design parameters needed to insure a continuous feedstock supply. Having known quantities of biomass in SSLs provides a Feedstock Manager an opportunity to minimize the at-plant storage cost.

4. Farmgate contracts that require a winter harvest must compensate for the loss of yield incurred by the delayed harvest.

5. Uncoupling of the unit operations in the logistics chain can provide an advantage.

(a) Baling uncouples the harvesting and in-field hauling operations. When the har­vesting operation is not constrained by in-field hauling, both unit operations can proceed at maximum productivity.

(b) When truck loading is uncoupled from hauling, the loading crew never has to wait for a truck to arrive and the truck never has to wait to be loaded.

6. Truck cost is the largest component of total cost in most logistics systems, thus it is essential to maximize truck productivity (tons hauled per unit time) by increasing tons/load and loads/day. A 10-min load time and a 10-min unload time is a desired goal for increasing loads/day.

7. The multibale handling unit was developed to solve the rapid load, rapid unload challenge.

8. Twenty-four-hour hauling can minimize truck cost ($/ton). The challenge is to find a way to load the trucks at night at a remote location.

9. The design of the receiving facility, because of the need to unload trucks quickly, is critical in the design of a complete logistics system.

10. Assigning different unit operations to different entities in the business plan can lower average delivered cost. For example, it is more efficient to pool all farmgate activities into a farmgate contract and have a hauling contractor handle all load-haul activities. This division is defined as a division between “agricultural” and “industrial” opera­tions. One key benefit achieved is in the capitalization of the equipment. Load-haul contractors can afford to invest in industrial-grade, high-capacity equipment designed for year-round operation as compared to farmgate contractors who will use their equip­ment 400 hours (or less) per year.

11. A biomass logistics system must be structured such that information technologies (GPS, bar codes, entry of data over cell phone network) and optimization routines developed for other logistics systems can be used to optimize asset utilization in real time.

Appendix 13.A Cost to Operate Workhorse Forklift (Example for Equipment Cost Calculations)

Machine selected for this study: Taylor Model TX 360M

$154 400 15 000 h

24 h/d, 7 d/wk, 47 wk/y = 7896 h 8% r = 0.08 $0.80/$100 value/y

x 0.80 = $1232/y

where

Co = ownership cost percentage (dec),

Sv = salvage value (dec), n = machine life (y), r = interest rate (dec), and K2 = factor for taxes and insurance (dec). K2 = 0.01 + 0.008 = 0.018 [3]

Annual ownership cost ($/h):

$81,004

7896

Operating Cost ($/h):

R/M + Fuel + Labor = Total

3 + 12 x 1.02 + 20 = $34.10/h

Ownership + Operating = Total

10.26 + 34.10 = $44.36/h

Total cost ($/dry ton):

Plant averages 23 dry ton/h $44.36/h

= $1.93/dry ton

Appendix 13.B Operational Plan for “Rack System” Example B.1 Operation Plan for SSL Loading

Ideally, the rack-loading operation at the SSL can load 16 bales in a rack in 20 minutes. This is a design goal which has not yet been attained with actual equipment. Discussion of how it might be achieved is presented later.

In a workday with 10 productive hours (600 min), a 20-min/rack operation can theo­retically load 30 racks, or 15 truckloads. An actual operation, given the reality of field conditions, cannot sustain this productivity. For this analysis, it is reasonable to assume that a mature operation can average 70% of the theoretical productivity. The number of loads/day/operation used for this analysis is 15 x 0.7 = 10.5 loads/d. The number of loading operations required is then

53 loads/d required at plant = 5 operations averaging 10.5 loads/d

This means that loading operations will be operating at five different SSLs for each workday and each will load, on average, 21 racks/d. Time to move the loading operation from one SSL to the next is not dealt with in this analysis, so the 21 racks/d productivity, averaged over an entire year, may be optimistic.

There are several options for a rack design. For this example, we chose the Side-load Option. It assumes a telehandler with special attachment will pick up two bales per cycle (Figure 13.B.1) and load these bales into the side of the rack while it remains on the trailer. We use the assumption that the average productivity that can be achieved under production conditions is 34 min/rack. Time required to load the two racks on a trailer is 68 min. Remember, this is the assumed average load time for year-round operation.

SSL operations — the loading of the trucks — is the most difficult challenge in the design of a cost-effective biomass logistics system. It is difficult to reduce the cost of these operations because the labor productivity (tons handled per worker per hour) tends to be low.

Figure 13.B.1 Concept for side loading bales into rack on trailer.

We choose to uncouple the SSL loading and hauling operations. This means we want a system where the truck does not have to wait for racks to be loaded in order to pick up the trailer. Also, the SSL crew does not have to wait for a truck to arrive to have a trailer with empty racks to fill.

The day-haul operations are uncoupled by providing two extra trailers at the “day haul” SSL, and the night-haul operations are uncoupled by providing nine extra trailers at the “night haul’ SSL. Each truck tractor then has a total of 11 extra trailers in the system. This is probably not an optimal (least cost) approach, but it does provide a reasonable starting point for this example.