Michigan State University Extension
Preserving Food Safely - 01600534
10/13/97

### ENERGY COST OF DRYING

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Let's calculate the energy cost of drying green beans  and
peaches
in a dehydrator built from plans in Home And  Garden
Bulletin
No.  217,  pages  16-20.   The   dehydrator   can
accommodate
18 pounds of fresh product.  Assume that  during
the
first  2 hours of drying time, all nine  75-watt  light
bulbs
(675 watts total) will be on.  Only six  light  bulbs
(450
watts total) will be left on for the remaining  drying
time.
Calculate  the energy cost at 5 cents  per  kilowatt-
hour.

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GREEN
BEANS

18 pounds = about 9 quarts

Drying time is 8 to 14 hours (average = 11 hours)

2 hours x 675 watts  = 1,350 watt-hours

=  1.35 kilowatt-hours

9 hours x 450 watts  = 4,050 watt-hours

4.05 kilowatt-hours

1.35 kilowatt-hours + 4.05 kilowatt-hours

kilowatt-hours     = 5.40

It takes 5.40 kilowatt-hours of electricity to dry about 9
quarts
of green beans.  That's equivalent to 0.60  kilowatt-
hours
per quart.
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0.60 kilowatt-hour x 5 cents/kilowatt-hour = 3.0 cents
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The energy cost of drying one quart of green beans is  3.0
cents.
(This   does   not   include  the  energy  cost  of
blanching
the beans as pretreatment for drying.)
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PEACHES

18 pounds = about 8 quarts

Drying time is 36 to 48 hours (average = 42 hours)

2 hours x 675 watts  =  1,350 watt-hours

=   1.35 kilowatt-hours

40 hours x 450 watts = 18,000 watt-hours

=  18.00 kilowatt-hours

1.35 kilowatt-hours  +  18.00 kilowatt-hours

kilowatt-hours    =  19.35
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It takes 19.35 kilowatt-hours of electricity to dry  about
8
quarts of peaches, or 2.42 kilowatt-hours per quart.
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2.42 kilowatt-hours x 5 cents/kilowatt hour = 12.1 cents
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So the energy cost of drying one quart of peaches is  12.1
cents.

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