TABLE II

ENERGY REQUIREMENTS:

MANUFACTURE AND DELIVERY OF NEW DRUM TO FILLER; RECONDITIONING AND DELIVERY OF USED DRUM TO FILLER

(1,000 BTU/drum)

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1 Table I down to and including transport to filler

2 Table I, transport to reconditioner, reconditioning energy, and transport to filler

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require twice as much energy as an all 18 gage system.

A complete 20/18 gage system would require 40% more energy than an all 18 gage system.

Table III is based on a systems analysis in which all flows of material on the flow chart have been estimated. The equation and an explanation of the variables upon which Table III is based are given in the Technical Appendix.

Table III is based on the reconditioning industry's conservative estimates of eight reconditionings per 18 gage drum (9 fills) and three reconditionings per 20/18 gage drum (4 fills). Lighter weight drums which can be reconditioned have an initial advantage over heavier drums until the number of reconditionings of the heavier drum exceeds that for the lighter drum. (Single-use drums are at a disadvantage after the first reconditioning of an 18 gage drum.) Lighter weight drums are less durable and generally cannot be reconditioned more than three times. The 18 gage drums, however, could be reconditioned up to 16 times with little problem. Any increase in the number of reconditionings will lower the energy requirements of the steel drum system.

CONCLUSION

The estimated energy requirements of the current mix of reusable and single-use steel drums in the United States is 73,532 billion BTU per year. If the system were converted to all 18 gage drums with an average of eight reconditionings (9 fills per drum) an estimated 17,043 billion BTU per year

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could be saved. This is enough to provide the equivalent in electrical energy for a city the size of San Francisco for one month.2

If the return rate of 18 gage drums were increased so that the average number of reconditionings was raised to 15 (16 fills per drum) then the United States could save an estimated 29,707 billion BTU per year, the equivalent of 238 million gallons of gasoline, by converting to an all 18 gage drum system. This would raise the ratio of energy requirements of the 22 gage single-use drum to 3 energy required for the 18 gage (16 use) drum to 2.5.

Clearly efforts to increase the use of 18 gage drums and the rate of return of such drums (by such means as deposits) would conserve energy. Conversely, a trend to

use more light weight drums or to reduce the return rate of drums would further burden American energy resources.

2 See Hannon, op. cit., p. 23.

3 If no losses occurred in the 18 gage system (no discards and no drum failures) the ratio would reach a maximum of 4.2. This is because as the number of reconditionings increases, the average energy approaches the reconditioning energy, since the energy required to manufacture the drum becomes a smaller and smaller fraction of the cumulative energy used. Mathematically, in equation A-4 of the Technical Appendix the average energy for the 18 gage drum approaches a lower limit of 265.5 x 10' BTU per fill as the number of fills becomes infinite. The average energy for the 22 gage drum is 1113.5 x 103 BTU per fill.

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References

1. Hannon, Bruce, "System Energy and Recycling: A Study of the Beverage Industry", Center for Advanced Computation, University of Illinois, CAC Document No. 23, revised March 17, 1973.

2. U.S. Bureau of the Census, Census of Manufactures, 1967, Special Series: Fuel and Electric Energy Consumed, MC67(S)-4, U.S. Government Printing Office, Washington, D.C., 1971.

3.. U.S. Department of Commerce, "U.S. Industrial Outlook, 1974, Metal Shipping Drums and Pails".

4. U.S. Bureau of the Census, Census of Transportation, 1967, Vol. III, Commodity Transportation Survey, Part 3, Commodity Groups, U.S. Government Printing Office, Washington, D.C., 1970.

5. U.S. Department of Commerce, "Current Industrial Reports: Steel Shipping Drums and Pails, Summary for 1967", M34K(67)–13.