| metric | system_boundary | source_category | MJ | units |
|---|---|---|---|---|
| Energy Use | Upstream | Energy use associated with production of fuels | 83.16052 | MJ |
| Energy Use | Post-Harvest | Energy use associated with mobile machinery | 756.23270 | MJ |
Crop Transportation
Methods 5.0
on-farm mechanical
postharvest
Energy and emissions of fuel used in the round trip to transport a harvested crop between the field and either the on-farm or off-farm post-harvest processing facilities.
Introduction
Crop Transportation Energy accounts for the energy of fuel used in the round trip of transporting the harvested crop between the field and the point of post-harvest processing. That may be either an off-farm point-of-sale (e.g. grain elevator, etc) or a crop storage and drying facility on-farm. The round trip involves a loaded trip and an empty trip, the order of which does not matter. For example, whether a cotton farm hauls their own cotton to the gin or a truck from the gin is sent to retrieve the cotton from the farm, there are two parts to the round trip: loaded and empty.
The energy associated with the actual harvest is accounted for separately from transportation as part of field operations.
Backhauling
Backhauling is an efficient logistics option in which the transportation vehicle travels to the farm loaded with imported feed or other goods instead of being an empty load. In this rare case, the fuel used in the return trip would not included in the Crop Transportation Energy component. The vast majority of farms are not backhauling (FBN data). In Fieldprint Calculator version 4.1, “no” was the selected default in the Fieldprint Calculator when users were asked about backhauling. In version 5.0, the backhauling question has been eliminated because it occurs rarely and the energy difference in fuel used would be minor in crop transportation.
Methods
Harvest weight
The weight of the crop harvested is most likely greater than the weight based on yield at standard moisture. Depending on the crop, users are asked to provide inputs:
How much moisture was removed by drying?
- For example, growers get receipts indicating delivery moisture; they are charged for each moisture point removed
Peanuts - What was the initial moisture content when delivered off-farm?
Cotton - Lint yield, which is converted later to seed cotton yield (lint + seed + trash)
Alfalfa - Harvest moisture (i.e., moisture at baling)
Transport Capacity and Fuel Efficiency
The crop transportation energy (\(E_{ct}\)) assumes a universal fuel efficiency and crop-specific truck capacities of semi-trailer trucks (see Table 5). The fuel economy of diesel (the default fuel choice) and B100 biodiesel is, for the Fieldprint Calculator, assumed equal given that MPG depends on unknown factors like engine setup and modifications. B100 is uncommonly used (USDOE, n.d.), but its potential has been demonstrated in pilot programs, producing much lower GHG emissions than diesel.
The fuel economy of the loaded trip is less than the empty trip. This is accounted for with an adjustment factor for higher fuel efficiency achieved with an empty, lighter truck (currently 25% more efficient). For crops grown for on-farm feed, such as corn silage or hay, a user enters the distance from the field to the on-farm storage. For crops with multiple harvest dates such as alfalfa, the crop transportation will have a distance entered for each harvest.
Logic for System Boundaries
Whether the transportation energy use and associated GHG emissions are assigned to “On-Farm Mechanical” or “Post-Harvest” (i.e. “Off-Farm”) depends on the crop and the location of post-harvest processing.
Most crops
If the user indicates that an on-farm facility was used for drying/storage, the Calculator will assign transportation energy and emissions to “On-Farm Mechanical”.
If the user indicates that an off-farm facility was used for drying/storage, the Calculator will assign transportation energy and emissions to “Post-harvest”.
If no drying is indicated by the user, the Calculator will assign transportation energy and emissions to “On-Farm Mechanical”.
Cotton
If the crop was cotton, then energy use and GHG emissions associated with crop transportation (and post-harvest processing like ginning and drying) are assigned to the “On-farm Mechanical” system boundary.
Alfalfa
Alfalfa is harvested at multiple times throughout the crop interval. Transportation energy and emissions are calculated for each harvest separately and then summed. Combining the individual harvests into one yield value prior to calculating transportation energy will likely result in underestimating the number of round trips.
Inputs
| Input | Value | Units | Symbol |
|---|---|---|---|
| Crop type | User entry | ||
| Crop yield at standard moisture | Based on user entry and crop type | kg/ha | \(Y_s\) |
| Crop yield at harvest moisture | Based on user entry and crop type | kg/ha | \(Y\) |
| Field area | Defined by user-entered field boundary | ha | \(A\) |
| Vehicle volume, or max load per trip | Table 5 | kg per trip | \(V\) |
| Number of trips | Calculated from vehicle capacity | \(n\) | |
| Transportation distance of one-way trip | User entry; between farm and point-of-sale (one-way) | mi per trip | \(d\) |
| Fuel type | Diesel1 or Biodiesel | ||
| Fuel efficiency - loaded | 6.9 | mi gal-1 diesel | \(e_{mpg}\) |
| Fuel efficiency - empty | \(e_{mpg}\times 1.25\) | mi gal-1 | |
| Fuel energy | ~ 144.9 ~ 126.1 |
MJ gal-1 diesel MJ gal-1 biodiesel |
\(E_{fuel}\) |
1 “The vast majority of truck fuel is diesel.” Heavy-Duty Vehicles Module | SEDS: Stochastic Energy Deployment System | NREL
Formulas
\[ n = \frac{YA}{V_{load}} \]
\[ V_{fuel} = 1.8\times \frac{n\ d\ }{e_{mpg}} \tag{1}\]
\[ E_{ct_{direct}} = V_{fuel}\times E_{fuel} \]
Steps
If needed, convert any standardized crop yields to harvest yield, and calculate the total weight being transported from the field.
- The units should match for crop yield and the truck capacity (e.g., kg of crop and kg/load)
Divide total amount of crop by vehicle capacity to determine total number of loads/roundtrips (\(n\)) needed to transport the crop.
- This number is rounded up as there is no such thing as a partial round trip.
Determine the volume of fuel burned by multiplying 1.8 times the total number of trips, distance between origin and destination, and dividing by the fuel efficiency \(e_{mpg}\) .
Calculate all direct and indirect energy and emission components
- For example, to calculate the upstream energy and emissions associated with the diesel manufacturing, the amount of diesel is multiplied by a given GHG component’s energy or emission factor per gallon (Table 6) .
Lastly, standardize to kg CO2e with Global Warming Potential factors.
Example: Transporting corn off-farm
The grower left their corn to dry in a 100 ac field before harvesting the corn at 180 bu/acre (adjusted to 15.5% moisture). A diesel-powered truck hauled the harvested corn one mile off-farm to the local elevator where it was dried 3% points. Calculate the energy use and emissions to haul all the grain from the field to the point-of-sale.
TipAnswer
About 5.22 gal of diesel were used to transport the crop, resulting in 839 MJ of total energy use and 59.3 kg CO2e emissions.
| metric | system_boundary | source_category | CO2_fossil | CO2_biogenic | CH4_fossil | CH4_biogenic | N2O | units |
|---|---|---|---|---|---|---|---|---|
| GHG Emissions | Upstream | GHG emissions associated with production of fuels | 5.085395 | 0 | 0.3621050 | 0 | 0.0278187 | kg_CO2e |
| GHG Emissions | Post-Harvest | GHG emissions associated with transportation of crop production | 53.237026 | 0 | 0.1413988 | 0 | 0.4344466 | kg_CO2e |
Example: Transporting cotton to local gin
| Input | Value | Units |
|---|---|---|
| Seed cotton yield conversion factor | 0.365 | units of lint per unit of seed cotton |
The reported cotton yield was 1200 lbs/ac of lint from an 100 acre field. What was the energy and emissions related to hauling all the bales of seed cotton to the gin 25 miles away for further processing?
TipAnswer
About 78.3 gal gallons of diesel were used to transport the crop, resulting in 12,591 MJ of total energy use and 889 kg CO2e emissions.
| metric | system_boundary | source_category | MJ | units |
|---|---|---|---|---|
| Energy Use | Upstream | Energy use associated with production of fuels | 1247.408 | MJ |
| Energy Use | On-Farm Mechanical | Energy use associated with mobile machinery | 11343.490 | MJ |
| metric | system_boundary | source_category | CO2_fossil | CO2_biogenic | CH4_fossil | CH4_biogenic | N2O | units |
|---|---|---|---|---|---|---|---|---|
| GHG Emissions | Upstream | GHG emissions associated with production of fuels | 76.28092 | 0 | 5.431575 | 0 | 0.4172803 | kg_CO2e |
| GHG Emissions | On-Farm Mechanical | GHG emissions associated with transportation of crop production | 798.55540 | 0 | 2.120982 | 0 | 6.5166991 | kg_CO2e |
Example: Transporting cotton to local gin using biodiesel
The cotton operation wants to know how GHG emissions will be affected if they switched to biodiesel (B100) as the transportation fuel. How would the previous answer change?
TipAnswer
About 78.3 gal of biodiesel were used to transport the crop. Total energy use was 15,689 MJ , with a total of 950 kg CO2e emitted.
Excluding biogenic CO2 lowers the emissions to 208.293901 kg CO2e, which is 76.6% fewer emissions than those in the previous example with petroleum-derived diesel fuel.
Tables
Crop Transportation Capacity
| crop | ton_per_load | kg_per_load |
|---|---|---|
| Alfalfa | 24.0 | 21772 |
| Barley | 27.0 | 24494 |
| Chickpeas (garbanzos) | 27.0 | 24494 |
| Corn (grain) | 27.0 | 24494 |
| Corn (silage) | 10.0 | 9072 |
| Cotton | 14.4 | 13063 |
| Dry Beans | 27.0 | 24494 |
| Dry Peas | 27.0 | 24494 |
| Fava Beans | 27.0 | 24494 |
| Lentils | 27.0 | 24494 |
| Lupin | 27.0 | 24494 |
| Mixed cover | NA | NA |
| Oats | NA | NA |
| Other broadleaf | NA | NA |
| Other grains | NA | NA |
| Peanuts | 23.0 | 20865 |
| Potatoes | 27.0 | 24494 |
| Rice | 27.0 | 24494 |
| Rye | NA | NA |
| Sorghum | 27.0 | 24494 |
| Soybeans | 27.0 | 24494 |
| Sugar beets | 27.0 | 24494 |
| Wheat (durum) | 27.0 | 24494 |
| Wheat (spring) | 27.0 | 24494 |
| Wheat (winter) | 27.0 | 24494 |
Energy and Emission Factors
| metric | system_boundary | source_category | source_detail | CO2_fossil | CO2_biogenic | CH4_fossil | CH4_biogenic | N2O | NF3 | SF6 | MJ |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Energy Use | Upstream | Energy use associated with production of fuels | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 74.33731 |
| Energy Use | On-Farm Mechanical | Energy use associated with mobile machinery | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 126.13190 |
| Energy Use | Post-Harvest | Energy use associated with mobile machinery | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 126.13190 |
| GHG Emissions | Upstream | GHG emissions associated with production of fuels | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 2.2449398 | 0.000000 | 0.0037037 | 0.0000000 | 0.0010976 | NA | NA | 0.00000 |
| GHG Emissions | On-Farm Mechanical | GHG emissions associated with transportation of crop production | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 0.0000000 | 9.482743 | 0.0000000 | 0.0000995 | 0.0000142 | NA | NA | 0.00000 |
| GHG Emissions | Post-Harvest | GHG emissions associated with transportation of crop production | Crop Transportation | Biodiesel (on-road heavy-duty truck) | 0.0000000 | 9.482743 | 0.0000000 | 0.0000995 | 0.0000142 | NA | NA | 0.00000 |
| Energy Use | Upstream | Energy use associated with production of fuels | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 15.93910 |
| Energy Use | On-Farm Mechanical | Energy use associated with mobile machinery | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 144.94460 |
| Energy Use | Post-Harvest | Energy use associated with mobile machinery | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 0.0000000 | 0.000000 | 0.0000000 | 0.0000000 | 0.0000000 | NA | NA | 144.94460 |
| GHG Emissions | Upstream | GHG emissions associated with production of fuels | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 0.9747006 | 0.000000 | 0.0023290 | 0.0000000 | 0.0000195 | NA | NA | 0.00000 |
| GHG Emissions | On-Farm Mechanical | GHG emissions associated with transportation of crop production | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 10.2037634 | 0.000000 | 0.0009094 | 0.0000000 | 0.0003050 | NA | NA | 0.00000 |
| GHG Emissions | Post-Harvest | GHG emissions associated with transportation of crop production | Crop Transportation | Diesel (on-road medium-heavy duty truck) | 10.2037634 | 0.000000 | 0.0009094 | 0.0000000 | 0.0003050 | NA | NA | 0.00000 |
References
USDOE. n.d. “Alternative Fuels Data Center: Biodiesel Blends.” https://afdc.energy.gov/fuels/biodiesel-blends.