Some of the highest yielding herbaceous biomass crops are thick- stemmed species. Their relatively high moisture content necessitates they be handled and stored as silage rather than hay bales or modules. This paper presents estimated costs of harvesting and transporting herbaceous crops as silage. Costs are based on an engineering- economic approach. Equipment costs are estimated by combining per hour costs with the hours required to complete the operation. Harvest includes severing, chopping, and blowing stalks into a wagon or truck

Butler, J.

Downing, M.

Turhollow, A.

UNT Digital Library

e 0 ic/Fd% ~%w- - 6 Energy Division and Environmental Sciences Division The Cost of Silage harvest and Transport Systems for Herbaceous Crops Anthony Turhollow Energy Division and Environmental Sciences Division Oak Ridge National Laboratory Mark Downing Energy Division and Environmental Sciences Division Oak Ridge National Laboratory and James Butler Prepared for 7* National Bioenergy Conference Nashville, Tennessee September 15-20, 1996 . Oak Ridge National Laboratory Oak Ridge, TN 3783 1-6205 managed by LOCKHEED MARTIN ENERGY RESEARCH COW. for the U.S. DEPARTMENT OF ENERGY under contract number DE-AC05960R22464 “The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. DE-ACO5-96OR22464. Accordingly, the U.S. Government retains a nonexclusive, royalty-6ee license to publish or reproduce the published form of this contribution, or allow others to do so for US. Government purposes” DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or amunes any legal liabili- ty or responsibiiity for the accuracy, completeness, or usefulness of any information, appa- ratus, product, or process disdased, or represents that its use would not infringe privately owned rights. Reference herein to any specific c~minercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n d y  constitute or imply its endorsement, reoommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessar- ily state or reflect those of the United States Government or any agency thereof. THE COST OF SILAGE HARVEST AND TRANSPORT SYSTEMS FOR HERBACEOUS CROPS Anthony Turhollow. Mark Downing, and James Butier' ABSTRACT Some of the highest yielding herbaceous biomass crops are thick-stemmed species such as energy cane (m ssp.), Napiergmss (- ), and forage sorghum (- ' ). Their relatively high moisture content necessitates they be handed and stored as silage rather than hay bales or modules. This paper presents estimated costs of harvesting and transporting herbaceous crops as silage. Costs are based on an engineering-economic approach. Equipment costs are estimated by combining per hour costs with the hours required to complete the operation. Harvest includes severing, chopping, and blowing stalks into a wagon or truck. For 50% moisture content. in-field costs using trucks in the field (options 0 and 1) are $3.72 to $5.99/dry Mg ($3.37 to $5.43/dt) for a farmer and $3.09 to $3.64/dry Mg ($2.81 to $3.3O/dt) for custom operators. However,slopesand wet field conditions may not permit trucks to enter the tield. Direct-cut harvest systems using wagons to haul silage to trucks waiting at the field edge (option 2) are $8.52 to $1 1.94/dry Mg ($7.73 to $10.83/dt) for farmers and $7.20 to %7.36/dry Mg ($6.53 to $6.68/dt) for custom operators. Based on 4 round trips per &hour day, 50 and 70% moisture silage, truck transport costs are $8.37/dry M g  ($ 7.601dt) and S13.981d1-y Mg ($12.68/dt), respectively. Lower yields, lower hours of machine use, or a higher discount rate result in higher costs. Keywords: cost. economics, herbaceous, biomass, silage, harvest, transport INTRODUCTION There are two types of forages: thin-stemmed (e.g. switchgrass) and thick-stemmed (e.g. sweet sorghum, energy cane). Thin-stemmed species can be handed as siiage (60%-70% moisture), haylage (40%-50% moisture), or hay (1 0%-20% moisture). Thick-stemmed species can be handed as silage or haylage. The 6andling systems considered for silage 'Anthony Twhollow. 15 1 1 E 2050 N. North Logan UT 8434 t -8804. Mark Downing, MS 6422, Building 1059, Oak Ridge, TN 3783 1. James Butler, 2823 Rainwater Rd., Tifion. GA 31794. and haylage are the same, and henceforth we will call both systems silage. The objective of this paper is to cost appropriate machinery complements for silage operations. The complements vary by f m  size and for a custom harvest operation. Capital costs range widely. For example, a pull-type forage harvester can cost as little as $14.000. whiie a self-propeiled (SP) forage harvester can cost as much as $ 170.000, with many options in between. There is a tradeoff between capital cost of equipment and labor requirements. To effectively use the more expensive equipment either a very large farm or a custom operation is required. Avore detailed information can be found in Turhollow et al(1996). Two methods are available for handling high moisture crops: 1) a direct-cut system and 3) a wilting (a cut. wilting in the fields. and pickup) system. If moisture content of the crop at harvest is below 75%, the direct-cut system can be used, otherwise it is necessary to reduce the crop's moisture content by letting it wilt in the field fkom 2 hours to 2 days. which reduces the moisture content to 40 to 50%. In general it is preferable to use the direct-cut system because less operations are involved and handling losses are lower. Four options for direct-cut silage are considered. Ail use a forage harvester to cut the crop. In option 0 the crop is then blown directly into a truck in the field. In option 1 the crop is blown into a wagon pulled by the forage harvester. then dumped into a truck in the field. In option 2 the crop is blown into a wagon pulled by the forage harvester. then dumped into a tractor-pulled forage wagon. and then dumped into a truck at the field edge. In option 3 the crop is blown into a wagon pulled by the forage harvester and unhitched when full and replaced by an empty wagon. The full wagon is then hitched to 3 tractor and hauled to the field edge and dumped into a truck. We cost options 0. I,  and 3 -. The direct-cut system requires a forage harvester to blow the cut material into a forage wagon or truck. The length of the chopped material can be controlled by changmg the knife configuration on the forage harvester. Forage harvesters can either be tractor pulled (pull-type) operating off the tractois power takeoff (PTO) or self-propelled. One advautage of a self-propelled over a pull-type is that cutting takes place in h n t  of the machine, not behind. We assume a small fanner doing his own harvesting would use a pull-type forage harvester while a very large farmer or custom operator would use a self- propelled forage harvester. This decision is based upon costs. IN-FIELD TRANSPORTATION Silage can be transported by truck a combination of trucks and wagons, or wagons. The silage or haylage systems under consideration h a d e  large volumes and masses. Fresh- cut silage is 426 kg/m3 (26 Ib/ft') (Rider et al 1993). Assuming fiesh-cut silage is at 70% moisture. then density is 125 dry kg'm' (7.8 dry lb/ft3). The thick-stemmed energy crops considered for handling as silage or hayiage will be more mature at harvest than typical corn silage, so we assume it is 50% moisture, and its density is 250 kg/m3 (15.6 ib/ft.'). Based on 22.4 dry Mg'ha [lo dry tons (dt/ac)], at 70% field efficiency a 2-row pull-type 0 forage harvester handles 112 mi (3300 ftj) or 28 Mg (25.4 tons)/hr and a 6-row self- propelled forage harvester handles 320 mj ( 1 1,400 ft3> or 80.7 Mg (89.0 tons) of biornasdhr. To reach the legal load weight limit which minimizes transportation costs. the truck transporting the biomass to the conversion facility requires approximately a 14.7 m (48') long, 3.5 m (1 1.4') tall. and 2.6 m (8.5') wide: or 11.3 m (37') long, 4.3 m (14') tall. and 2.6 m (8.5') wide truck trailer. Blowing directly into a truck (option 0) appears to be the least cost method, by minimizing the amount of equipment required, the number of operations. and maximizing active forage harvesting time. Disadvantages of this system are: the truck driver has to constantly keep up with the forage harvester. not all field conditions (e.g. wetness and slope) are suitable for the truck. the 4.3 m ( 14') tall truck is too high for forage harvesters to blow into, losses are higher blowing into a truck without a roof as opposed to a forage wagon with a roof, and the exact weight of the biomass blown into the truck is unknown, making it possible to go over the legal weight limit. For option 1, even though dumping time is a relatively short 1 to 2.5 minutes, because of the large volumes of biomass handled. a high capacity wagon is desired. Wagons with roofs have capacities up to 3 1.2 m' (1 100 ft3) and wagons without roofs up to 25.5 mi (900 fY). Given that the truck transporting the silage to the conversion facility can transport a 22.7 Mg (25 ton) [91 mi (3200 ft3)] load. then 3 wagon loads of 30.3 mi (1068 ft3) or 7.56 Mg (8.33 tons) each [based on 250 kg/m' (15.6 Ib/fY)] or 4 loads of 22.7 m3 (800 ft3) are required to til1 the truck. We assume a forage harvester-pulled wagon has a scale. to ensure a truck is not overloaded. and it costs $3495. Standard dumping height for a high dump forage wagon is about 3.4 m (1 1') and with risers about 3.5 m (1 1.4'). If the truck trailer is 4.3 m (14') high then an extra high dumping wagon is needed. For option 2 the tractor-pulled wagon has no a roof. The largest high dump wagon without a roof we know of is 25.5 rn; (900 ft3), can dump over 4.3 m (14') high, but has a 2.5 minute dump cycle. It is possible to haul a smaller andor less expensive wagon behind the forage harvester. If dumping from one forage wagon to another. a 4.3 m (14') high dumping clearance is not required but the standard 3.4 m (1 1') dumping clearance is adequate. The Miller Pro Model 4012, capacity of 22.7 m3 (800 fP) and 8.2 Mg (9 tons) and dump cycle of 1 minute is an example. The disadvantage of this wagon is that the dumping height limits the height of a truck one can dump into, if one wants to sometimes use a higher than 3.5 m (1 1.4') trailer. For option 2 we cost 22.7 m3 (800 e) wagons. For option 3, for a forage harvester with a 2-row head, hitching and unhitching would be acceptable from a time perspective. but for a self-propelled harvester with a 6-row head this would result in too much downtime for the expensive forage harvester and reduce tield eEciency to about 50%. For option 2. tractor-pulled forage wagon. total round trip time is 15.5 minutes; 9 minutes for travel. 2.5 minutes to be dumped into by the forage harvester hauled wagon, 2.5 minute to dump into a truck. and 3 minutes of slack time. Thus each wagon makes 3.87 round tripshr. A 22.7 rn’ (800 ftj) wagon carrying 5.66 Mg (6.24 tons) or 2.83 dry Mg (3.12 dt) has a capacity of 2 I .9 Mg (24.2 tons) or 1 1 .O dry Mg ( 12.1 dt)/hr. The number of forage wagons required to transport silage from the field to the field edge depends on crop yield and moisture content, the forage crop head used, and its associated rate of operation (ha/hr or ackr), and the hourly capacity of each wagon. Four different row heads are considered (2 row, 3 row, 4 row, and 6 row). Based on 22.4 dry Mg/ha (10 dt/ac), for 22.7 m3 (800 p) wagons. a 2-row head requires 2 wagons, a 3-row head requires 2 wagons. a 4-row head requires 3 wagons [note that the 4-row head on a 201 kW (270 hp) forage harvester is limited to 21.7 Mgha (9.7 ddac) or a slower fieid speed by its power], and a 6-row head requires 4 wagons. COSTS Costs can be broken into the following categories: depreciation (or capital replacement) interest insurance, housing, and taxes repair fuei. lube. and oil labor The ASAE ( 1995) has formulas to determine values of farm equipment after n years. The value as a percent O f  inkid list price is 68(0.920)” for tractors; 64(0.885)” for combines. cotton pickers. and SP windrowers: 56(0.885)” for balers, forage harvesters, blowers. and SP sprayers: and 60(0.885)” for ail others. Equipment is used for a certain number of years, based on assumed hours of life divided by hours of use. Depreciation on a straight-line basis is: depreciation/hr = (purchase price - discounted salvage value)/hrs of life where purchase price is 90% of initial list price. We use a real interest rate of 6% (or in nominal terms about 9%). The averqe amount of interest paid in a year is: interest = [(purchase price - discounted salhge value)/2]*interest rate . A S S  (1 995) provides values for total lifetime undiscounted repair costs. Lifetime undiscounted repair costs are divided by number of hours of life to get repairs cost per hour. Insurance. housing, and taxes are 2% of list price. From ASAE D497.2MAR94 and assuming X = 0.5 (Walsh 1995), typical diesel fuel consumption is: L = maximum PTO power (kW) * 0.252 or gal = maximum PTO power (hp) * 0.04938. Oil and lube costs are 15% of fuel costs. Diesei cost for off-road use (Le. farm equipment) is assumed to be $0.21 1/L ($0.80/gallon) and for trucks is $0.3045 ($1.15/gailon). The difference is road use taxes. For field labor, the number of labor hours required is 1.25 times the number of machine hours required. This allows for time spent transporting and setting up machinery. Labor is charged at $8/hr, including benefits. for agricultural operations (or $ IO/hr of a d  equipment operation) and $1 5/hr for trucking, including benefits. Area covered is determined fiom data in ASAE ( 1995) on equipment speeds, widths, and field efficiencies. T m c w  over-the-road -n costs Fuller et ai ( 1992) list the price of a tandem truck of $46.000. annual use of 500 hrs. a lifetime of 5000 hrs, repair costs of S2.3Oh. and diesel use of 17.8 L/hr (4.7 gailons/hr). The price oftruck listed is a net cost. 3 any dealer discounting is included. To adjust for inflation between 1992 and 1995 and for dealer discounting we assume a 1995 list price of $58,000 and to adjust for inflation repair costs of $2.53/hr. X silage truck is assumed to have a list price of$80.000. a lifetime of 5000 hrs, and operates 400 Myear. The 400 operating Myear  is based on a custom silage operation working 400 Myear  and the trucks that haul silage are used in a just-in-time manner (i.e. they haul silage when silage is being harvested) with no off-site (eom the conversion facility) storage. Fuel use is the same as for the tandem truck. Repair costs are proportional to dative list prices of the silage and tandem truck, $3.49hr ($80.000/$58,000*$2.53/hr). A silage truck operates 8 hours in an 8-hour working day and makes four round trips in a working day. Total cost including labor is $47.48/hr or $380/8-hr working day. Silage transport costs $8.37/dry Mg ($7.60/dt) for 50% dry matter content (baseline case) and $13.98/dry Mg ($12.68/dt) for 30% dry matter content (Table 1). - Table 1. Silage transport costs Tractor COSQ Four tractor sizes are costed (including labor costf(Tab1e 2). Tractors are used with all field equipment except those that are self propelled and heads on self-propelled equipment. Table 2. Tractor costs Sources: ASAE ( 1995), NAEDA ( 1995) The first machines used for direct-cut silage systems are pull-type or self-propelled forage harvesters. We calculate costs for two pull-type: a forage harvester with a 2-row head powered by a 1 I9 kW (1 60 hp) tractor and a forage harvester with a h o w  head powered by a 1 5 7 k W (2  I O  hp) tractor (Table 3 1. These are heavy-duty pull-type forage harvesters. We also calculate costs for two self-propelled forage harvesters: a 20 1 kW (270 hp) model with a Crow head and a 32 1 kW (430 hp) model with a six-row head (Table 32). All four configurations are capable of handling 22.4 dry Mg/ha (10 dt/ac) yields except the 201 kW (270 hp) self-propelled model, which is limited to 2 1.8 dry Mg/ha (9.7 dt/ac) or a slower approach field speed by its available power at the assumed cut length of 9 mm (0.35"). At a longer cut length the 201 kW (270 hp) seif-propelled model could handle 22.4 dry Mg/ha (10 dt/ac). Based on average field spetds h m  ASAE (1 999, the coverage of the forage harvesters is controlled by the head size aud the assumed 76 cm (30") row width. Forage harvesters are expensive to operate, costing between $55 and $121/hr and $67 to $106/ha ($27 to $43/acre) (including labor) at 70% field efficiency. c High dump forage wagons are used in all options except option 0. If the wagon is puiled behind a forage harvester it is assumed to have both a roof and scale. If silage is dumped from the harvester-pulIed wagon into a tractor-pulled wagon the tractor-pulled wagon has no scale and no roof. Using high volume wagons. 22.7 and 3 1.1 m3 (800 and 1 100 v), these wagons cost between $14.39 and %17.55/hr (Table 4). If they are hauled by a 34 kW (45 hp) tractor. the tractor costs an additional S I7 .25h (including iabor). Table 3 .  Forage harvester costs. harvester 201.41 270) 40001 101 400( 116000 74.051 61.59 21.93 1-row head 201.4 2701 2000 5 4001 10000 8.66) 1.20 2.97 7.20 1.92 total 196000 82.70 68.79 27.85 SP forage harvester 4000 101 400 168000 104.53 6-row head 320.81 4jO( 2000 51 400 19000 16.45 1.80) 4.45 9.121 3.69 220.8 4301 I 57.96 23.46 total i I87000 120.98 I 67.081 27.16 Sources: ASAE (1999, NMDA (1995) at 70% field efficiency Table 4. Costs for high dum1 r imulement scale, risers, dump clearance 3.47 m ( 1  I .4?, roof no scale. dump clearance 4.57 rn (1 5'). no roof scale. risers. dump clearance 3.37 m ( 1 1-47. roof Sources: ASAE ( 1995). Mille 3 !I forage wagons used for silage annual capacity life use list price totalcost Im5 'fp hr lvears hr s $nu I ~~~ ~22.7  I800 I2000 I 10 I 200 1 16160 I 14.39 22.7 800 2000 10 200 19200 17.10 31.2 IllOOl 2000 I 10 I 200 I 19710 I 17.55 I *-St. Nazi= ( 1993, NAEDA (1995) In-field production costs for options 1 and 2 based on 50% moisture content are shown in Table 5. They range from $3.09 to $1 1.94/dry Mg ($2.81 to $10.83/dt). Silage transport costs add $8.37/dry Mg ($7.60/dt). Tabie 5. In-field production costs for options 1 and 2 based on 50% moisture content r option0 I option 1 I option2 option0 I option 1 I option2 $/dry Mg $/dt pull-type (farmer) 2-row head 4.74 5.991 11.94 4.30 5.43 10.83 3-row head 3.72 4.551 5.52 3.37 4.13 7.73 self-propeiled (custom operator) 4-row head 3.161 3.641 7.361 2.87 3.301 6.68 6-row head 3.091 3.481 7.201 2.8 1 3.161 6.53 REFERENCES ASAE. 1995. ASAE standards 1995.42nd ed. American Society of Agricultural Engineers. St. Joseph. MI. Fuller. E., B. Lazarus. L. Carrigan. and G. Green. 1992. Minnesota farm machinery economic cost estimates for 1992. AG-FO-2308C. Minnesota Extension Service. University of Minnesota. St. Paul, iMN. Miller-St. Nazianz. 1995. Miller Pro hydraulic dump boxes. promtional literature. Miller-St. Nazianz, Inc.. St. Nazianz WI. NAEDA. 1995. Guides 7000: 0 7  * NorthAmerican Equipment Deaiers Association, St. Louis, MO. Rider, A., A. Barr and A. Pauli. 1993. Hav * 4 t h d D e c h 6 2  Company Service Publications, Moline. IL. Turhollow. A., M. Downing, and J. Butler. 1996. Herbaceous crops harvest and transport costs. Forthcoming O W L  T/M. Oak Ridge National Laboratory, Oak Ridge, TN. * Walsh. M. 1995. Uses of switchgrass as a dedicated energy crop - costs of production. 

The cost of silage harvest and transport systems for herbaceous crops

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The cost of silage harvest and transport systems for herbaceous crops

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