Chptr9PrblmSolns - SOLUTIONS FOR CHAPTER 9 9.1 Analysis of...

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SOLUTIONS FOR CHAPTER 9 9.1 Analysis of the recycling rates using Table 9.8 data and prices from Table 9.18 a. Carbon savings is 747MTCE b. At $50/ton, tipping fee savings is 936 tons/yr x $50/ton = $46,800/yr c. Revenue generated is $118,845/yr d. With a carbon tax of $50 per metric ton of carbon-equivalents, savings due to recycling would be 747 MTCE/yr x $50/MTCE = $37,350/yr 9.2 Analyzing the energy side of the airport recycling program described in Problem 9.1 using Table 9.9 a. Annual energy savings is: 21,494 million Btu b. At $5 per million Btu, the dollar savings is 21,494 million Btu/yr x $5/million Btu = $107,470/yr c. Dollar savings per ton would be: $107,470 / 936 tons = $114.81/ton 9.1
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9.3 Spreadsheet analysis for the recycling program using Tables 9.8 and 9.18. a. Avoiding $120/ton for pick up and selling these recyclables at half the Table 9.18 market price for recyclables saves Avoided pick up charges = 5300 ton/yr x $120/ton avoided = $636,000/yr Revenue from sale of recyclables = $404,000/yr Total savings = $636,000 + $404,000 = $1,040,000/yr b. With a $10/ton of CO 2 tax, recycling saves Carbon tax = $10/ton CO 2 2000 lb/ton x 2200 lb metric ton x 44 ton CO 2 12 ton C = $40.33/MTCE Savings = $167,531/yr (from spreadsheet) c. A $400,000/yr recycling program saves Net benefit = $1,040,000 + $167,531 - $400,000 = $807,531/yr 9.4 Comparing a 10,000mi/yr, 20 mpg SUV burning 5.22 lbs C//gal at 125,000 Btu/gal to cardboard recovery savings. c. The carbon savings from cardboard recycling is equivalent to carbon emissions from how many SUVs? d. How many “average SUVs” of energy are saved by cardboard recycling? a. How many tons of CO 2 will be emitted per SUV per year? CO 2 = 10,000 miles x x 5.22 lbsC/gal 20 miles/gal x 2200 lbs/ton x 44 tonCO 2 12 tonC = 4.35 ton CO 2 /yr b. Btus for those SUVs Energy = 10,000 miles x 125,000 Btu/gal 20 miles/gal = 62.5 million Btu/yr c. From Table 9.10, 42 million tons of cardboard are kept out of landfills. And from Table 9.8, each ton saves 0.96 metric tons of carbon 9.2
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Car equivalents = 42x10 6 ton/yr x 0.96 mtonC/ton x 1.1 ton/mton 4.32 tonCO 2 /yr SUV x 44 tonCO 2 12 tonC = 37.6 million SUVs taken off the road in carbon savings d. From Table 9.9, cardboard recycling saves 15.65 million Btu/ton. So, Car equivalents = 42x10 6 ton/yr x 15.65 x10 6 Btu/ton 62.5 x 10 6 Btu/yr/SUV = 10.5 million SUVs 9.5 A 0.355-L (12 oz) 16 g aluminum can with 70% recycling. Need to adjust Table 9.13 which was based on 50% recycling. Each can now has 0.7x16 = 11.2 g of recycled aluminum and 0.3 x 16 = 4.8 g of new aluminum from bauxite. New aluminum from bauxite = 4.8g x 1765 kJ 8g = 1059 kJ Recycled cans to make 11.2 g of Al=11.2g x 40 kJ 8g = 56 kJ The remaining energy for can production is the same as Table 9.13: Total for 16g (0.355L) can = 3188 – (1765 + 40) + (1059 + 56) = 2498 kJ/can Per liter of can = 2498 kJ/0.355L = 7037 kJ/L 9.6 Heavier cans from yesteryear, 0.0205 kg/can and 25% recycling rate. New aluminum per can was 0.75 x 0.0205 kg = 0.015375 kg Recycled aluminum per can was 0.25 x 0.0205 kg = 0.005125 kg From Table 9.12: New aluminum = 0.015275 kg x 220,600 kJ/kg = 3370 kJ Recycled aluminum = 0.005125 kg x 5060 kJ/kg = 26 kJ Total energy = 3370 + 26 = 3396 kJ/can Compared to today’s 1805 kJ/can (Example 9.4) Today : 1805 kJ/can Earlier : 3396 kJ/can = 0.53 Savings is 47% 9.7 Using 1.8 million tons/yr of aluminum cans, 63 percent recycled, and Table 9.12: a. The total primary energy used to make the aluminum for those cans.
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This note was uploaded on 04/03/2008 for the course C E 370 taught by Professor Burgos during the Spring '08 term at Pennsylvania State University, University Park.

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Chptr9PrblmSolns - SOLUTIONS FOR CHAPTER 9 9.1 Analysis of...

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