3. Assume that a banana has a food energy content of 100 kcal and weighs 100 g,

Question

3. Assume that a banana has a food energy content of 100 kcal and weighs 100 g, and that a raspberry has a food energy content of 1 kcal and weighs 2 g and that a serving of raspberries is 25 raspberries. Use air, truck and ship freight energy intensity values from the Transportation Energy chapter of the lecture notes. Specifically you may use 3000 Btu/ton-mile for trucks, 500 Btu/ton-mile for ships, 300 Btu/ton-mile for trains, and 22.000 Btu/ton-mile for air transport. For a personal vehicle (car or SUV) you may use 20 miles per gallon.

Explanation / Answer

e)

A) we consider both banana and raspbery serving one by one

now first of alll for a banana the energy = 100kcal

Now the effeciency of suv is 20 miles per gallone.

to go 2 miles we need 2 / 20 = 0.1 gallone liquid

now 1 gallone = 31477 kcal

then 0.1 gallone = 3147.7 kcal

Therefore a trip to the store for the banana means energy consumption of 100 + 3147.7 kcal = 3247.7 kcal

similrly for the raspberry serving total energy consumption = 1 * 25 kcal + 3147.7 kcal = 3172.7 kcal

B) now for grocery store trip we consider that the truck is used.

then enery for transport = 3000btu/ton-mile or 3000 * .2521kcal/ ton-mile = 756.3 kcal/ ton-mile

a serving of raspberry means 25 kcal and for 2 ton-mile the transport energy = 2 * 756.3 kcal= 1512.6 kcal

so overall consumption = 25 + 1512.6 kcal = 1537.6 kcal.

f)

for 2 mile the oil consumpton is 0.1 gallone which costs = 0.1 * 3 = 0.3 $

The cost of the banana is .25$ then .3 /.25 = 6/5 fraction is the transportation cost

Again, the cost of the raspberry serving is 1$ then .3 / 1 =3 /10 fraction is the transportation cost

g)

We consider that C8H18 burns with the O2 in air to give Co2 and H20

therefore

balanced equation gives

2C8H18 + 25O2 = 16 CO2 + 18 H2O

So, 114.228 gm C8H18 gives 44.0095 gm CO2 or green house gas

the banana is of 100gm then for 100 gm the CO2 emission is 44.0095 * 100 / 114.228 gm = 38.52gm

and the raspberry serving has the CO2 emission = 44.0095 * (2 * 25) / 114.228 gm = 19.26 gm [25 raspberries each of 2g]

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