Download Assume that coal creates 0.97 lb of CO2/ kWh of heat and CH4

Assume that coal creates 0.97 lb of CO2/ kWh of heat and CH4 produces 0.39 lb of CO2/ kWh of heat Efficiency
= kWh of electricity/kWh of heat 1000 kg = 1 metric ton, 2000 lb = 1 ton
Gasoline contains 115,400 BTU/gal, Ethanol contains 75,670 BTU/gal
1. (Learning objective #6) Today one gallon of “gasoline” costs $3.85. This gasoline contains 10% ethanol (E10).
If the gasoline was 100% gasoline, how much should it cost? ( $3.99/gal)
2. (Learning objective #8) You need to calculate how much VOCs is released by your coating facility per year.
For each of the following, calculate how much VOC is emitted per year. (These are as easy as they seem…)
a. Workers use a single spray gun with a capacity of 5 gallons per hour. The coating contains 75% VOC by
weight and its density is 9.85 lbs/gal. The workers use this gun 8 hours/day for 250 days in a year.
b. Painters use 30 gallons of latex (water based) paint during the year. The paint contains 1.19 lbs of VOC
per gallon.
c. Painters use 7 gallons of oil based trim paint per year. Oil base paint contains 3.69 lbs of VOC per gallon.
d. Workers use 9 gallons of clean-up solvent per year. You can assume that the solvent is 100% VOC and that
the specific gravity is 0.87.
e. Your facility installed 5000 ft2 new carpet this year that emits 0.2 mg VOC/ m2 of carpet per hour.
3. (Learning objective #8) New regulations dictate that mercury must be limited to 15 tons of per year from
power plants. Assume bituminous coal contains 50 mg of Hg per ton of coal and that 13,200 Btu of heat is
produced for every lb of coal. Assume an efficiency of 50%.
a. How many mg of Hg are produced for every BTU of electricity produced? (3.8 x 10-6 mg/ BTU electricity)
b. What is the maximum amount of electricity (in Btu) that can be produced by coal and still satisfy the
mercury requirements? (3.6 x 1015 BTU electricity/year)
4. (Learning objective #15) Currently Penn State produces 20,000 MWh of electricity from its coal - fired power
plant by burning 7500 metric tons (1 metric ton = 1000 kg) of coal. Coal 6.67 kWh of heat for every kg of coal.
a. What is the efficiency of the power plant?
b. How many kg of CO2 are produced every year by burning coal at Penn State? (48 million lbs)
c. Penn State will switch to natural gas. Methane has a heat capacity of 1011 BTU/ft3 and a density of 0.042
lb/ft3. How many kgs of CO2 will be released if the new plant is 55% efficient? (14 million lbs)
d. If 1% of the methane leaks, how much equivalent kgs of CO2 total will be produced? (15 million lbs)
5. (Learning objectives #11, #15, #16) The US uses 8.5 million tons of cement per year. You need 120 kWh of
electricity to make one ton of cement. Assume that natural gas has a heating content of 0.3 kWh heat/ft3, a
density of 0.042 lb/ft3 and that it burns with an efficiency of 55%.
a. Calculate the lbs of natural gas (CH4) required to produce enough energy to create 8.5 million tons of
cement. (2.6 x 108 lb CH4)
b. Calculate the total lbs of equivalent CO2 released if 99.5% of the methane is burned and 0.5% of the CH4 is
released into the environment without being burned. Global Warming potential of CH4 = 23. (7.4 x 108 lb CO2)
c. Calculate how many equivalent miles are driven per year per person to equal the amount of CO2 produced
from the energy used in producing cement? The US population is 317 million people. Assume that the average
car gets 27.5 mpg and that gasoline can be represented as C8H18 with a density of 6.15 lb/gal. (Use the answer
to question 2 here). (C = 12 g/mole, H = 1 g/mole, O = 16 g/mole) (3.38 miles driven per person)
6. (Learning objectives #8, #15) Pennsylvania is the fourth leading coal producing state, mining 55 million tons
of coal last year. They used this to produce 500 trillion Btu of electricity. Pennsylvania power plants emitted
130,683 tons of NOx, or about 80 percent of all the NOx emitted in the state.
a. Assuming the heating content is 13,200 Btu/lb of coal, calculate the efficiency of coal-fired power plants in
PA. (34.4%)
b. Calculate how many lbs of NOx would be saved if the efficiency was changed to 42%. Assume you still need
to provide 500 trillion Btu of electricity. (4.7 x 107 lbs NOx per year)