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From farm to table

An energy consumption assessment of refrigerated, frozen and canned food delivery Scientific Certification Systems Kirsten Ritchie, B.S., M.S., P.E. Civil Engineering

Introduction

Within the context of creating greater efficiencies in society’s use of energy, one of the most important industries to consider is the food industry. Providing the most basic fuel of all from the human perspective, the food supply chain utilizes energy at every stage of moving agricultural produce from the field to the table: growing/harvesting, processing, packaging, transporting, storing for wholesale and retail distribution; and preparing the food in the nation’s home kitchens. Quantifying the energy requirements at every stage depending on the form of packaging gives us an opportunity to provide energy efficiencies that will affect not only the industry, but the environment, as well.

Table i-1. Relative use of energy within the entire food production system

Energy Consumption

 RefrigeratedFrozenCanned
StageKcal/lb%Kcal/lb%Kcal/lb%

Production

320

19-28%

320

13-14%

320

20-26%

Processing

9

1%

825

34-37%

261

16-23%

Packaging

160-670

14-40%

180-236

7-10%

374-659

33-41%

Transportation1

306-360

21-27%

136-158

6-7%

119-239

11-15%

Storage2

187-209

11-18%

537-764

25-32%

0

0%

Preparation

146

9-13%

159

7%

61-127

5-8%

Total

1152-1692

100%

2250-2046

100%

1136-1607

100%

1 Based on 1500 mile transport distance

2 Based on 10 day storage cycle for refrigerated goods and 90 days for frozen

The consuming public in general does not understand the complexities of the modern global food system. They tend to live and shop for groceries far away from where food was produced and processed. They rarely stop to consider whether the food was imported and sold at a grocery chain that takes five minutes by automobile to reach, or whether it was grown by local farmers and sold at a greengrocer within walking distance of their homes. (Jones, 2002) When considering the price of food, few take into account the environmental costs related to producing, processing, storing or transporting food. Among the largely unseen environmental costs is the increased amount of fossil fuel required to transport food over long distances combined with the electricity needed to keep these foods cold or frozen. As is clearly shown in Table i-1 these energy related impacts are considerable.

Consumers in the U.S. and other developing countries have come to expect a continuous supply of diverse foods. This requires significant reliance on processing and packaging to preserve food, as well as transportation of fresh foods from production regions of the nation to parts of the country with limited growing seasons. The energy consumed in this process is a good indicator of environmental impact. In general, the energy to process and package food today is much greater than the energy provided by the product.

In this study we are assessing the energy requirements for transporting perishable foodstuffs such as fruits and vegetables in three forms of packaging: refrigerated fresh produce, frozen, or canned. In addition, we will be comparing all three packaging approaches in two delivery formats: bulk (e.g. green beans and lettuce) and portion servings (e.g. blueberries sold in small packets).

Assessment Boundaries

This assessment considers energy expenditures for the energy consumed in the movement of produce from farm to table for the three primary modes of delivery: refrigerated, frozen and canned.. However, as is common in life cycle assessment practice, the energy used to build the processing and distribution facilities, the stores, the homes or the trucks and cars used to transport the goods is not included.

Product Groupings

While the original intent of the study was to investigate specific product groups, namely green beans, sweet corn, blueberries, peaches, chicken and ravioli, during the course of investigation, it became apparent that an alternative assessment approach would prove more informative.

Hence, the decision was made to move from a product specific assessment to a packaging/ processing combination. The following combinations were selected:

A – Bulk refrigerated product (e.g. green beans, broccoli, asparagus, lettuce, apples, and peaches)

B – Portion packaged refrigerated product (e.g. 4 oz blueberries, raspberries, sliced mushrooms) C – Bagged frozen product (e.g. blueberries, sliced peaches, green beans, corn kernels)

D – Boxed frozen product (e.g. spinach, frozen ready meals)

E – Canned ready meals, full content utilization (e.g. soup, ravioli, chili, tomatoes)

F – Canned goods with processing liquid (e.g. green beans, sliced peaches, blueberries, tuna, chicken)


1. production

comestible products reaching the marketplace. Energy inputs derive from such varied components of the production phase as seed sourcing and irrigation, herbicides and insecticides, as well as direct fuel consumption associated with harvesting and transport to processing facilities or market (Pimentel & Pimentel, 2003).

Based on currently available literature from Pimentel (1996 & 2003) as well as others (Duke 1983; Wilkins & Eames-Sheavly), the energy inputs associated with key crops range from approximately 130 Kcal/lb for oranges (1.23 Mj/kg) to 518 Kcal/lb for spinach (4.78 Mj/kg) as shown below in Table 1-1.. While the range of energy required to grow different crops is definitely measurable, the result set is still within the same order of magnitude.

Table 1-1: Production Energy Consumption (Growing and Harvesting)

Energy Consumption

Production

 Production YieldEnergy InputsEnergy consumption per unitData Source
Productkg/hakcal/hakcal/kgkcal/lbMj/kg 

Apples

54,743

28,980,000

529

240

2.22

1

Oranges

40,370

11,862,000

293

133

1.23

1

Potatoes

34,384

16,038,455

466

212

1.96

1

Spinach

11,200

12,759,849

1139

517

4.78

1

Tomatoes

49,616

16,560,443

333

151

1.40

1

Brussels sprouts

12,320

8,060,328

654

297

2.75

1

Soybeans

1,882

1,827,223

970

441

4.07

1

Snap beans

4,995

4,623,482

925

420

3.88

2

Corn

7,965

7,047,000

884

402

3.71

3

Strawberries

     

390

3.60

4

Average

     

320

2.96

1 - Pimentel and Pimental 1996
2 - Duke JA 1983
3 - Pimentel and Pimental 2003
4 - Wilkins J & Eames-Sheavly M (online access 2005)

Interestingly, the energy inputs per hectare do not directly translate to energy consumption.

It is important to consider the yield, as well as the total energy inputs per hectare, in quantifying the energy consumption associated with production of a particular product.

For example, the energy requirement to produce a hectare of apples is close to 29 million kcal/ha, compared to corn at 7 million kcal/ha. However, the significantly higher yield of apples (about 55,000 kg/ha) as compared to corn (about 7900 kg/ha) results in corn requiring 80% more energy to be consumed per hectare of production than apples.

For the purposes of this report, we assume that the upstream life cycle stages associated

with agricultural components until the processing phase are essentially the same regardless of whether the produce ends up being canned, refrigerated or frozen. It is true that in some cases, the variety of fruit or vegetable to be grown is selected for its characteristics relative to canning or freezing, but the energy consumption differential (for machinery, fuel, pesticides or fertilizers) is not considered to be of measurable difference. Therefore, for purposes of a comparative energy evaluation the average energy input value of 320 Kcal/lb was used for all product groupings.

Clearly, those interested in assessing the relative energy impacts for a particular crop such as Brussels sprouts or snap beans can utilize the specific data provided. For example, if we were interested in a comparative evaluation of corn, we’d replace the average value of 320.75 Kcal/lb for the actual value of corn of 402.16.

Examining the total energy inputs in the farm to table food chain, energy consumed in production activities (growing and harvesting) as a percent of the total energy consumption from 11% for frozen goods to 28 % for select refrigerated and canned goods as shown in Table i-1.

It should be noted that the data used to derive this information necessarily lags a couple years behind, and the recent expansion of organic production requiring less energy-intensive inputs, e.g. synthetic fertilizers, suggests addition research to update the data set.

2. processing

This study focuses on the three primary processing methods used for moving product from

farm to table: refrigeration (fresh with minimal processing), freezing and canning. There are other methods used such as drying, smoking, salting and freeze drying, but far and away the largest majority of product moves to market today refrigerated, frozen or canned.

Previous studies from such industry experts as David and Marcia Pimentel have assumed no energy inputs associated with the movement of fresh product. As described below, this is no longer accurate given that fresh (e.g. refrigerated product) typically involves as a minimum some rapid cooling step, such as forced air or hydro cooling.

Refrigeration:

According to studies by the Nova Scotia (Canada) Department of Agriculture and Fisheries (1994), it is imperative to have proper post-harvest cooling and handling of fruits and vegetables to ensure maximum quality. The rate of deterioration after harvest is mainly influenced by the respiration rate of the harvested product. Since the rate of respiration is related to temperature, removal of field heat before storage, “pre-cooling”, will reduce the respiration and deterioration rates. Pre-cooling also reduces the growth of decay organisms, reduces water loss and reduces the production of ethylene, a gas produced by plants that accelerates ripening and senescence.

The two most important factors, according to the Canadians, are temperature and time, i.e. a fruit or vegetable must be cooled in the shortest time possible, preferably within one to 15 hours. Product cooling follows a logarithmic function, with rapid cooling initially followed by a slower and slower rate.

Typical pre-cooling methods include: room cooling, forced air (pressure cooling), hydro-cooling, package icing and vacuum cooling.

In room cooling, a refrigerated room is designed to hold produce once the field heat is removed. For most fruits and vegetables room cooling is generally considered inadequate due tot he slow rate of cooling, e.g. days instead of hours and excessively dehydrates the product (bring this up into sentence).

Forced air or pressure cooling is achieved by pulling refrigerated room air through a stacked product. This is generally accomplished using fans which can move at least 1 cu. ft. per pound of air under vacuum under 1 inch (25 mm). “In a properly designed forced air system the evaporative coils in the refrigeration system have more surface area than conventional coils, allowing for more rapid heat removal,” according to the researchers in Nova Scotia. Since they do not need as low a temp as conventional coils there is less dehydration of air. “This method is considered the more versatile because it is easily incorporated into existing cold rooms, does not require sophisticated technology, and can be used on the widest array of fruits and vegetables, and types of packaging.”

Hydro cooling cools the product by immersing or showering it in cold water. It is faster than forced air, and does not de-hydrate the product, but should only be used if the product can tolerate being wetted and not damaged by falling water disinfectants. This activity is more energy-intensive than forced air-cooling, as the water must be cooled by mechanical refrigeration. However, due to its limited product applicability, we are recommending using forced air refrigeration as a more reasonable comparative basis in this study.

Package-icing: Some products can be cooled by adding ice to the packed container. This method can cool product faster than forced-air, but the product must be able to tolerate contact with water and ice. Although the easiest method is to add flaked ice to the top of the container, greater contact with the product can be achieved by injecting a slurry of water and ice into the package. Care must be taken to ensure complete distribution in the package. Containers must be watertolerant with holes for water drainage. (Novia Scotia, 1994)

Vacuum cooling: In vacuum cooling, the packaged product is placed in an air-tight chamber and the air is evacuated. Although this method can cool product in less than 30 minutes it is only effective in products with a high surface-area-to-volume ratio. Vacuum coolers are limited in use because they are expensive to purchase and operate, and can only be used on a limited range of products.

While there are ranges of pre-cooling technologies available for use, the most common and versatile is forced air. It is estimated to take 1 BTU to lower the temperature of one pound of product one degree Fahrenheit. Therefore, assuming an average 35 degree required temp drop e.g. from a field temp of 70 degrees to a cool room temp of 35 degrees, this would result in an energy consumption of 8.83 kcals/lb (0.08 mj/kg).

Freezing:

Many of the desirable qualities of the fresh food are retained for relatively long periods of time with freezing. The temperatures employed, -18° or lower, retard or prevent the growth of harmful microbes. Their growth is also inhibited by lack of water, which is frozen. (Pimentel & Pimentel, 1996)

Fruits can be frozen dry with added dry sugar, or in syrup. Vegetables must be blanched (boiled or steamed for a short time) prior to freezing to inactivate plant enzymes that cause deterioration of natural flavors and colors. Pimentel (1996) also notes that the energy input for freezing fruits and vegetables is much greater than that for required for canning, averaging 1815 kcal/kg of frozen food versus only 575 kcal/kg for canning. (The figure of 575 kcal/kg represents only the energy expended in actual processing by heat and does not include the energy input required for making the container.)

Canning:

Since Louis Pasteur proved that microorganisms, invisible to the eye, caused foods to putrefy and that this putrefaction was not spontaneous decomposition, various methods of heating foods to temperatures high enough to kill harmful micro-organisms have been used to make preserved food safe for human consumption. The basic process in canning foods is to heat the food to boiling or higher, pack, and completely seal it in sterilized containers. The precise processing temperatures and times used depend upon the acidity, density, and other characteristics of the particular foodstuffs being processed. Foods with a pH of 4.5 or higher require the high heat of pressure canners to ensure complete destruction of the Clostridium botulinum heat-resistant spore. (Pimentel, 1996)

As reported by Pimentel, energy inputs associated with canning range from 575 kcal/kg of food processed when processing occurs at a large industrial facility, to as high as 1200 kcal/kg for home processing.

Summary of Processing Energy Inputs

Provided below in Table 2-1 is a summary of the energy inputs required for processing. It is important to note that in this study we are relying on information provided by Pimentel for the freezing and canning energy figures. However this data is over 10 years old and therefore it would be appropriate to assess its veracity due to potential processing changes that have occurred in the intervening time.

Table 2-1: Energy Inputs associated with product processing

MethodPackageProcessing Energy Inputs% of Total Energy Inputs
 

MJ/kg

kcal/lb

%

Refrigerate

Bulk

0.08

8.8

0.8

Portion

0.08

8.8

0.5

Average

0.08

8.8

0.6

Frozen

Bagged

7.62

825

34.3

Boxed

7.62

825

36.7

Average

7.62

825

35.5

Canned

Ready Meal

2.41

261

23.0

Fruit & Vegetable

2.41

261

16.3

Average

2.41

261

19.6

Our findings indicate that even with the introduction of pre-cooling such as forced air, the energy inputs associated with processing of refrigerated product are significantly less than for canned, i.e. forced air cooling 8.8 kcal/lb (0.08 mj/kg) versus 260 kcal/lb (2.41 mj/kg) for canned product. However, the energy inputs for canning, in turn, are significantly less than those reported for frozen goods (260 kcal/lb (2.41 mj/kg) compared to 825 kcal/lb (7.62 mj/kg).

Examining the total energy inputs in the farm to table food chain, the range of percentages of energy consumed in processing as a percentage of the total energy consumption ranges from less than one percent for bulk refrigerated goods to more 30% for select frozen goods.

3. packaging

One of the most critical steps in the food supply chain is the packaging of product. However, this is also one of the most energy intensive steps. Packaging is necessary to protect food from environmental impacts, as well as maintenance of product quality.

In evaluating the energy inputs associated with packaging it is necessary to consider both the range of material types used, as well as the converting operations required to turn the material (such as rolled steel) into a useable product (i.e. a steel can). In addition, one must consider both the primary package, e.g. the steel can used to hold the soup, as well as the cardboard tray and film containing 12 cans, used primarily for efficiencies in transport.

Shown below Table 3-1 are field findings regarding packaging materials used for various commonly available products in today’s marketplace, along with an assessment of the package material to food weight ratio.

Table 3-1: Summary of packaging material and weights

ManufacturerProductPackageGrossWeightNet Weight (stated)Food Product WeightPackage WeightPackage weight to Food weight ratioPackaging MaterialDimensions
   ozozozozoz/ oz  
Primary Packaging
Del Monte Cut Green Beans Canned - F&V 16 14.25 8 1.9 0.24 Steel Can 2-7/8 x 4- 3/8
Oregon Fruit Products Blueberries in Light Syrup Canned- F&V 16.2 15 6.7 2 0.30 Steel Can 2-7/8 x 4-3/8
Swansons White Premium Chicken Breast Canned- F&V 5.9 4.5 3.4 1.2 0.35 Steel Can w/ pull tab top 3-1/8x1-1/2
Hain Organic Whole Kernel Corn Canned - F&V 17.5 15.25 9.7 1.9 0.20 Steel Can 2-7/8 x 4- 3/8
Amy’s Organic Soups Chunky Tomato Bisque) Canned -Meal 16.5 14.5 14.5 2 0.14 Steel Can 2-7/8 x 4- 3/8
Campbells Chicken Noodle Soup Canned -Meal 12.3 10.75 10.9 1.4 0.13 Steel Can 2-5/8 x 4
Progresso Beef Barkely Soup Canned-Meal 22.4 19 19.7 2.7 0.14 Steel Can 3-3/8x4-1/2
Big Valley Frozen Blueberries Frozen - Bag 12 12 12 0.2 0.02 LDPE 1x9x6
C&W Frozen Whole Petite Beans Frozen - Bag 14 14 14 0.2 0.01 LDPE 1x9x7
Stouffers Spinach Souffle Frozen - Box 13.3 12 12 0.7 0.06 Coated Lquidboard 6-3/4x5x1-1/4
C&W Spinach Souffle Frozen - Box 10.9 10 10.2 0.7 0.07 Coated Lquidboard with film 5-1/2x4- 1/4x1-3/8
Altar Asparagus Refrigerated - Bulk 280.5 240 240 40.5 0.17 Coated cardboard 7-3/8x12- 3/8x17-1/4
Healthy by Choice Broccoli Refriger ated - Bulk 365.9 320 320 45.9 0.14 Coated cardboard 12-1/8x11- 5/8x19-5/8
Driscoll’s Fresh Raspberries Refrigerated - Portion 6.8 6 6.4 0.4 0.06 2 PS 5x5x
Very Berry Marketing (VBM) Blueberries - Chile Refrigerated - Portion 5.4 4.4 5 0.4 0.08 PET 4-1/4x4- 1/4x1-1/2
Secondary Packaging
Newman’s Own Herb Salad (bagged) Refrigerated 118.9 105.6 105.6 13.3 0.13 Cardboard Box 7-1/4X11- 5/8X15-5/8
Muir Glen Crushed Basil Tomato Crushed Basil Tomato Canned 340.1 336 336 4.1 0.01 Cardboard Tray 2-1/8x12- 1/2X16-3/8
Canned 336.8 336 336 0.8 0.00 Plastic Stretch Film  
Deicabo Cherry Tomatoes Refriger ated 137.1 128 128 9.1 0.07 Cardboard Tray 3-7/8x11- 7/8x15-5/8

Energy consumption in production of packaging materials

The primary packaging materials that are used in the transport of refrigerated, frozen and canned goods include tin-plated steel, cardboard, LDPE, polystyrene, PET and coated paperboard (liquid board). For this study, we are using life cycle inventory data primarily prepared for the Swiss Packaging Institute by the Swiss Federal Laboratories for Materials Testing and Research (EMPA). While this data is based primarily on Swiss factors, it is of sufficient quality to support comparative analysis for use in North America.

Table 3-2 below, provides the calculated energy requirements for production and conversion of these key materials on a kilogram weight basis. Included are energy requirements for production of the primary material as well as for converting operations, such as converting tin-plated steel sheet into cans. As shown, the energy requirements for material production range from a low of 9 mj/kg for recycled content corrugated cardboard to 18 mj/kg for recycled content steel sheet, to 80 mj/kg for polystyrene. For converting operations, energy consumption ranges from less than 0.5 mj/kg for cardboard to 6.2 mj/kg for canned production. The data presented for the plastics (LDPE, PET and polystyrene) include values for total energy consumption as well as that just associated with production, e.g. excluding gas and oil used as feedstock in the manufacture of these polymers.

Table 3-2: Energy inputs associated with package material production and conversion

Packaging MaterialPrimary Energy ConsumedFeedstock Energy ConsumedConversion Energy Consumed
 MJ/kgMJ/kgMJ/kg

Tin Plated Steel (60% recycled content)

18.0

0

6.2

LDPE

36.4

42.7

0.3

Corrugated Cardboard (from mixed fibers) 9.1 0.1 0.5

Liquid Packaging Board

24.8

0.3

1.4

PET

34.8

41.1

3.6

Energy impacts of refrigerated goods packaging

As you can see from the table above, refrigerated goods can be delivered in both bulk, e.g. 15-20 lb. boxes of asparagus and broccoli, or in apportioned containers, e.g. 4-6 oz. packages of blueberries and raspberries. For portioned product, there is additional secondary packaging, typically stackable cardboard trays that contain anywhere from 24 to 48 individual units.

As shown on the table for bulk products, the typical package weight-to-food weight ratio ranges from 0.14 to 0.17 (ounce to ounce), that is .14 lbs of package to every pound of actual food delivered. In the case of portioned product, this ratio drops to 0.06 to 0.08.

This is due in large part to the lightweight nature of the plastic packaging (PET or PS) used in lieu of heavy-duty cardboard for the bulk products. The packaged weight-to-food ratio for secondary packaging is calculated to be about 0.07 pounds of package to one pound of food delivered. Again, this material is primarily cardboard.

Applying these package weight ratios to the material energy requirements shown above in Table 3-2. results in packaging energy loads for refrigerated goods ranging from 160 kcal/lb to 670 kcal/lb. See table 3-3, below:

Table 3-3: Packaging Material Energy Consumption, Refrigerated Goods

 Bulk RefrigeratedPortion RefrigeratedAverage
 MJ/kgKcal/lb% TotalMJ/kgKcal/lb% TotalKcal/lb% Total
Primary                

Material

1.43

153.15

13.30%

5.31

569.85

33.68%

361.50

23.49%

Converting

0.07

7.48

0.65%

0.25

27.04

1.60%

17.26

1.12%

Secondary

           

0.00

 

Material

0.00

0.00

0.00%

0.64

69.17

4.09%

34.58

2.04%

Converting

0.00

0.00

0.00%

0.03

3.38

0.20%

1.69

0.10%

TOTAL PACKAGING 1.50 160.64 13.95% 6.24 669.43 39.57% 415.04 26.76%

Energy impacts of frozen goods packaging

For frozen goods, delivery is generally either in bagged or boxed form. Bags are typically manufactured using low-density polyethylene (LDPE), and boxes are coated containerboard or liquid board. As shown on table A/PK, the ratio of package weight to food weight for bags ranges from 0.1 to 0.2, whereas boxes range from 0.06 to 0.07. Combining this ratio data with the materials information provided in Table B/PK, we find the energy consumption associated with frozen goods ranges from 180 kcal/lb to 236 kcal/lb as shown below in Table 3-4. Approximately 65% of this energy is associated with the primary packaging and 35% with the secondary packaging, i.e. cardboard boxes in which the bags and individual boxes are shipped.

Table 3-4: Packaging Material Energy Consumption, Frozen Goods

 Bagged FrozenBoxed FrozenAverage
 

MJ/kg

Kcal/lb

% Total

MJ/kg

Kcal/lb

% Total

  

Primary

               

Material

1.19

127.39

5.29%

1.63

174.90

7.77%

151.14

6.53%

Converting

0.00

0.49

0.02%

0.09

9.62

0.43%

5.06

0.22%

Secondary             0.00  

Material

0.46

49.40

2.05%

0.46

49.40

2.20%

49.40

2.12%

Converting

0.02

2.41

0.10%

0.02

2.41

0.11%

2.41

0.10%

TOTAL PACKAGING 1.67 179.70 7.47% 2.20 236.34 10.50% 208.02 8.99%

Energy impacts of canned goods packaging

When evaluating the packaging of canned goods, one must be cognizant of the impacts resulting from the actual quantity of food delivered. For example, as shown in Table 5, a 16 oz. can of green beans with a declared net weight of 14.25 oz. of product in actual effect is only delivering 8 oz. of green beans, with the remaining 6.25 oz. being ancillary liquid. On the other hand, a 16 oz. can of soup with a net weight of actual soup of 14.5 oz. delivers 14.5 oz of food product. Taking these variables into account, we find that the

package weight-to-food weight ratio for canned fruits and vegetables, as well as for canned meats such as tuna and chicken, ranges from 0.2 to 0.35 pounds of packaging per pound of food. This compares to a ratio of 0.13 to 0.14 pounds of packaging per pound of food for such ready to eat items as soup and chili.

As shown below in Table 3-5, the resulting energy inputs for packaging of canned product ranges from 373 kcal/lb for ready meals to over 650 kcal/lb for fruits and vegetables. The energy associated with the primary packaging for canned goods represents over 90% of the total packaging load. This is due in significant part to the fact that the steel container is strong enough to support its own weight and therefore only minimal secondary packaging is required to expedite transport and warehousing.

Table 3-5: Packaging Material Energy Consumption, Canned Goods

 Canned Ready MealsCanned Fruits & VegetablesAverage
 

MJ/kg

Kcal/lb

% Total

MJ/kg

Kcal/lb

% Total

Kcal/lb

% Total

Primary

               

Material

2.53

271.11

23.86%

4.45

477.67

29.73%

374.39

26.80%

Converting

0.86

92.37

8.13%

1.52

162.75

10.13%

127.56

9.13%

Secondary

               

Material

0.09

9.88

0.87%

0.16

17.29

1.08%

13.59

0.97%

Converting

0.00

0.49

0.04%

0.01

0.85

0.05%

0.67

0.05%

TOTAL PACKAGING 3.48 373.85 32.91% 6.14 658.56 40.99% 516.20 36.95%

Final thoughts on packaging

Shown below in Table 3-6 is a summary of energy inputs associated with of different product packages, both primary and secondary packaging typically found in today’s marketplace.

Table 3-6: Energy inputs associated with primary and secondary packaging

Method

Package

Packaging Energy Inputs

% of Total Energy Inputs

  MJ/kgKcal/lb%

Refrigerated

Bulk

1.50

160.64

13.95%

Portion

6.24

669.43

39.57%

Average

 

415.04

26.76%

Frozen

Bagged

1.67

179.70

7.47%

Boxed

2.20

236.34

10.50%

Average

 

208.02

8.99%

Canned

Ready Meal

3.48

373.85

32.91%

Fruit & Vegetable

6.14

658.56

40.99%

Average

 

516.20

36.95%

Examining the total energy inputs in the ‘arm to table food chain, the range of percentages of energy consumed in packaging activities (including both primary and secondary, material as well as converting operations) as a percent of the total energy consumption across the food chain ranges from 6% for frozen goods to over 40% for select canned and refrigerated items.

4. Transportation

Another key consumer of energy in the food supply chain is transportation. The impacts of this sector have grown significantly in recent years due in no small part to the further distances that product is moved. Whereas in previous times food was grown and harvested within a 500-mile radius, today’s product for the American consumer is typically grown and produced 2000 miles away. In some cases such select products such as raspberries, are flown in from Chili or winter green beans from Africa.

In calculating transportation energy consumption, one must consider not only the distance traveled, but the quantity of product that can be moved as well as the temperature in which it must be controlled. For purposes of this study we are focusing on the shipment of product by truck within the continental U.S. We recognize that other shipping techniques such as rail, and ocean and air transport, play an important and increasingly significant role in the movement of product, but at this point in time in North America, the majority of product is moved by containerized truck transport.

On average, the fuel efficiency (mile per gallon) of containerized truck transport is 8 miles per gallon. When a container requires refrigeration, an additional one gallon per hour is consumed. (Source: personal conversation with trucking industry) Assuming an average 50 miles per hour distance traveled, the fuel efficiency for a refrigerated container changes from 8 miles per gallon to 6.9 miles per gallon. The energy input of fuel (i.e. diesel) is 135 MJ/gallon.

Shown below in Table 4-1 is the of energy consumed for the distance traveled.

Table 4-1: Energy consumption for selected travel distances

Transport Type

100 miles

500 miles

750 miles

1000 miles

1500 miles

3000 miles

 

MJ

MJ

MJ

MJ

MJ

MJ

Insulated (8 mpg)

1.688

8.438

12.656

16.876

25.313

50.625

Refrigeration Add-on (1 gph) 270 1.350 2.025 2.700 4.050 8.100
Refrigerated Total 1.958 9.788 14.681 19.575 29.363 58.725

When determining the energy consumed in the transport of a kilogram of product, one must take into account, as mentioned before, how much product can be moved in a container. The nature of food and differing packaging types result in a wide variation of food density within a given container. As shown in table 4-2, below, product densities can range from a low of 10.8 lbs/cu.ft., e.g. apportioned blueberries, to a high of 50 lbs/cu.ft. for canned soups. Assuming an actual 75% available capacity in a standard 40-foot container, the net weight of food transported can range from a low of 17,000 lbs. (blueberries) to a high of 80,000 lbs. (soup). However, weight constraints in effect limit the higher end allowed to only 60,000 lbs. Therefore, while theoretically possible to transport over 90,000 lbs of canned products in a truck, federal transportation rules prohibit this, resulting in a reduction of overall transportation efficiencies for canned precuts.

Table 4-2: Product volume and densities, select food products

Manufacturer

Product

Volume (calculated)

Net Density (calculated)

Food Product Density (calculated)

Gross Weight in 40 ft3 container (75% capacity)

Food Weight in 40 ft3 container (75% capacity)

Storage Volume (ft3/lb)
  ft3lb/ft3lb/ft3   
Primary Packaging
Del Monte Cut Green Beans 0.016 54.21 30.44 95097.89 47548.94 0.03
Oregon Fruit Products Blueberries in Light Syrup

0.016

57.07

25.49

96286.61

39822.24

0.04

Swansons

White Premium Chicken> reast

0.007

42.26

31.93

86569.59

49887.56

0.03

Campbells

Chicken Noodle Soup

0.014

47.70

48.36

85258.68

75554.44

0.02

Progresso

Beef Barkely Soup

0.023

51.00

52.88

93927.46

82605.85

0.02

Hain

Organic Whole Kernel Corn

0.016

58.02

36.90

104013.31

57653.09

0.03

Amy’s Organic Soups

Chunky Tomato Bisque) 0.016

55.17

55.17

98069.69

86182.46

0.02

Driscoll’s

Fresh Raspberries

0.029

12.96

13.82

22946.33

21596.54

0.07

Very Berry Marketing (VBM)

Blueberries - Chile

0.029

9.50

10.80

18222.08

16872.30

0.09

Big Valley

Frozen Blueberries

0.029

25.92

25.92

40493.52

40493.52

0.04

C&W

Frozen Whole Petite Beans

0.029

30.24

30.24

47242.44

47242.44

0.03

Stouffers

Spinach Souffle

0.024

30.72

30.72

53191.49

47992.32

0.03

C&W

Chopped Spinach

0.019

33.60

34.27

57219.82

53545.15

0.03

Altar

Asparagus

0.911

16.46

16.46

30061.51

25721.08

0.06

Healthy by Choice

Broccoli

1.601

12.49

12.49

22317.85

19518.21

0.08

Combining transportation energy consumption requirements with payload variables, the energy consumed for transport of products is found to range from a low of 120 kcal/lb. for ready meal canned goods to a high of 360 kcal/lb. for portioned product (see Table 4-3 below). This is based on an average 1500 miles transport distance utilizing a 40 foot transport container, with a 75% volume capacity or 50,000 pound payload constraint. The majority of the energy consumption is associated with the distance traveled, although the component associated with refrigeration is still significant enough to warrant consideration.

Table 4-3: Energy consumption for product transportation

 Bulk RefrigeratedPortion RefrigeratedAverage Refrigerated
 MJ/kgKcal/lb% TotalMJ/kgKcal/lb% TotalKcal/lb% Total
Transport

2.46

264.13

22.94%

2.90

310.62

18.36%

287.38

20.65%

Refrigeration

0.39

42.26

3.67%

0.46

49.70

2.94%

45.98

3.30%

TOTAL - Refrigerated Goods

2.86

306.39

26.61%

3.36

360.32

21.30%

333.36

23.96%

 

Bagged Frozen Goods

Boxed Frozen Goods

Average

 MJ/kgKcal/lb% TotalMJ/kgKcal/lb% TotalKcal/lb% Total
 

MJ/kg

Kcal/lb

% Total

MJ/kg

Kcal/lb

% Total

Kcal/lb

% Total

Transport 1.27 136.19 5.66% 1.10 117.68 5.23% 126.94 5/45%

Refrigeration

0.20

21.79

0.91%

0.18

18.83

0.84%

20.31

0.87%

TOTAL - Frozen Goods 1.47 157.99 6.57% 1.27 136.51 6.07% 147.25 6.32%
 

Canned Ready Meals

Canned Fruits & Vegetables

Average

 MJ/kgKcal/lb% TotalMJ/kgKcal/lb% TotalKcal/lb% Total
 

MJ/kg

Kcal/lb

% Total

MJ/kg

Kcal/lb

% Total

Kcal/lb

% Total

Transport

1.11

119.49

10.52%

2.23

238.98

14.87%

179.24

12.70%

Refrigeration

0.00

0.00

0.00%

0.00

 

0.00%

0.00

0.00%

TOTAL - Canned Goods

1.11

119.49

10.52%

2.23

238.98

14.87%

179.24

12.70%

Examining the total energy inputs in the ‘farm to table’ food chain, the range of percentages of energy consumed in transportation activities (both miles as well maintaining refrigerated temperatures) as a percent of the total energy consumption across the food chain ranges from over 5% for frozen goods to over 27% for select refrigerated items.

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