Assume that you have a gas-powered automobile that goes 26 miles on one gallon o
ID: 173759 • Letter: A
Question
Assume that you have a gas-powered automobile that goes 26 miles on one gallon of gasoline. You drive that automobile l4,000 miles per year. Based on the average amount of carbon present in a Joaquin Miller Park redwood tree, according to the data taken by our class, how many of those trees would be required to offset the carbon generated by your use of that automobile over the course of one year? (Be sure to tell me what the average amount of carbon in the redwood tree is, according to our data.) Use the carbon value numbers and methods provided in the attached excerpt from an Environmental Protection Agency publication ("Greenhouse Gas Emissions from a Typical Passenger Vehicle at https://www.epa.govisites/production/files/2016- 02/documents/420fl4040a.pdf and show all calculations.Explanation / Answer
Answer:
Average amount of carbon present in Joaquin Miller Park Redwood tree:
We will determine Redwood Tree mass first using the formula:
Tree mass (kg) = Volume of the tree (m3) x density of the wood (kg/m3)
For Redwood tree assuming diameter around 20 feet or 6m and average height ~ 200feet = 61m
Considering cylindrical shape of the redwood tree, the volume (m3) can be calculated using the formula:
Tree volume (m3) = Tree height x diameter x 0.7854 - all measurements in meter
Tree volume (m3) = 61m x 6m2 x 0.7854 = 1725m3
Approximate density of wood = 700 kg/m3
Tree mass (kg) = Volume of the tree (m3) x density of the wood (kg/m3) = 1725 x 700 = 1207500Kg = 1.2 millionkg
CO2 sequestered per tree (kg) = Tree mass (kg of fresh biomass) x 65% (dry mass) x 50% (Carbon %) x 3.67 x 120%
For Redwood CO2 sequestered per tree (kg) = 1207500 x 65% x 50% x 3.67 x 120% = 1728295 kg
Redwood tree reaches full height when it is around 600 years age.
Therefore CO2 sequestered per tree in a year = 1728295 kg / 600 = 2880 kg/year
carbon generated by automobile over the course of 1 year
CO2 emission from a gallon of gasoline = 8887 grams CO2/gallon
Average MPG for gasoline Vehicles in U.S. = 21.6miles/gallon and drives around 11400 miles per year
Tail pipe CO2 emission for a passenger vehicle: CO2 emission per mile = CO2 per gallon/MPG = 8887/21.6 = 411grams
Average annual CO2 emissions = CO2 emission/mile x number of miles = 411 x 11400 = 4685400g = 4.68 metric ton or ~ 4.7 metric tons per year
Average annual CO2 emissions for vehicle = 4685 kg/year
CO2 sequestered per Redwood tree in a year = 2880 kg/year
Therefore Number of Redwood Trees required to offset the CO2 emission from vehicle over the course of 1 year = 4685/2880 = 1.62 or 2 trees per year