Dcpppf is correct, one option to decrease fuel usage is increasing efficiency.
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Other options include:
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decrease output
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increase idle/ down time
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creative accounting, perhaps you could securitize the less full tanks and then group the empty portion of the securitizations into collateralized tank obligations (CTO) which you could sell to investors who will be confident that the FED will bail them out once the ponzi scheme implodes.
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2. Make sure it is loaded to its best efficiency point, if possible. This point will be stated by the manufacturer.
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