Outline: ChE 150, March 4, 2009

1. Outline: ChE 150, March 4, 2009 • Pollution prevention: source reduction / recycling / treatment / disposal • Economics of Recycling • Life Cycle Analysis

2. Pollution Prevention Priority: Reduce quantity of waste stream altogether: “any practice which reduces the amount of pollutant entering any waste stream or otherwise released into the environment” (EPA, 1991) Source Reduction Recycling Reuse of materials that would otherwise be disposed of. decreasingpreference Chemical, biological or physical processes to reduce or eliminate waste material (incineration) Treatment UltimateDisposal Pollution Prevention: Problems & Solutions, 1994

3. {rate of “stuff” generation} {rate of “stuff” in} {rate of “stuff” out} { rate of accumulation of “stuff” } - + = Pollution problems can be approachedusing Mass, Species, or Energy Balances control volume

4. Homework Problem: Analysis of Recycling

5. Economics of recycling MRP: Marginal Recycling Profit – arising from resale of used materials MRP = dp/dQR $ Q* Qu* MCD: Marginal Cost of Disposal – includes landfill disposal and waste incineration. 0 Q Q*: “optimal recycling” Qu* : where we would be withoutregulation MCD = dC/dQD Optimal recycling involves a marginal cost (no profit!) *Kirkwood, R. C., Longley, A. J. Clean Technology and the Environment. Chapman & Hall, Glasgow 1995

6. Taxes can be used to repartition costs. Disposal taxes: Landfill tax (per ton), subsidy for incineration MRP = dp/dQR $ Q* Qu* 0 Q Product taxes: Per unit volume Virgin materials taxes: E.g. PET plastic in unformed state. MCD = dC/dQD Ideally, taxes would respond to curve shapes and level of societal recycling / reuse.

7. Disposal is another form of pollution. What do we do with our waste? Landfill ~85% Other e.g. incineration, sea dumping physical, chemical treatment ~15% Inappropriate disposal of waste has negative social side-effects (externalities). External costs: noise, smell, unsightliness External benefit: recovery of methane or energy recovery (incineration)

8. What is a Life Cycle Analysis? A systematic approach to define and evaluate the total environmental load associated with a product or service. Materials • Process includes: • Maintenance • Infrastructure • running of the university… • ( a fraction thereof) paper, pencils, electronics Emissions Process ChE 150 Associated with materials Energy transport, heating, … production of electronics Residuals garbage Product acquired knowledge (course credit) • System can includes all up- and downstream environmental effects. • Determine what’s significant and what is negligible

9. Processes can be complex– consider the manufacture of a wooden pencil • Pencil ingredients • Amorphous graphite: Mexico • Clay: Bavaria (Germany) • Petro-derived wax • Superbond • Californian Cedar wood • Lacquer polish & paint • Operations • Mixing, grinding of graphite and clay • High pressure extrusion through die • Furnace baking (1200 °C) • Drying, aging Understanding the ultimate environmental impacts of such a process is a daunting task.

10. Key Steps of a Life-Cycle Analysis? 1) Define a goal for the LCA 2) Define system boundaries 3) Normalization: choose a basis for comparison 4) Inventory: collect and tabulate data (difficult) 5) Scoring: Impact assessment 6) Analysis In any LCA report, sufficient details must be provided such that your study could be reproduced.

11. Example of a LCA: Paper or Plastic? 1,2 Step 1: Define Goal Compare the paper and plastic bags on the basis of energy used and pollutants produced. • Energy used: • Energy to manufacture bag(process energy) • Energy contained in material (feedstock energy) • Pollutants considered: • solid • atmospheric • waterborne 1. Franklin Associates, Ltd. 1990 2. <http://www.nedlac.org.za/research/fridge/plastics/life.pdf>

12. Generalized steps of a process; think “cradle-to-grave”. Primary Resources Emissions Resource acquisition Material Manufacture Energy Product Fabrication Use Residual transport Disposal

13. Step 2: Define System Boundaries Generic Life Cycle of Plastic Carrier Bags VCB = Vest type carrier bag

14. Step 2: Define System Boundaries (con’t) Generic Life Cycle of Plastic Carrier Bags

15. Step 3: Choosing a convenient basis Based on carrying capacity Volume capacity ~ 1.5 : 1 (paper to plastic) Weight capacity ~ 2 : 1 (paper to plastic) Rational: enables comparison of product that achieve same service For our class discussion, single paper bag will be compared to two plastic bags

16. Step 4: Collect data and tabulate results • Methods to acquire data • Survey data (difficult and costly) • large enough sample size • representative samples • Example of survey questions: printing of paper bags • what inks are used? • how much process energy is required? (printers ops, transport to bag-forming step, etc.) • how is waste dealt with? • Other data sources • Industry reports • Governmental reports The integrity of your results rests upon that of your data!

17. Step 4: Collect data and tabulate results Step Energy Mater. Pollut. Other Notes Pulp production - - - - Paper production - - - - Print - - - - Form to bag - - - - Bale - - - - Retail - - - - Consumption - - - - Waste - - - - Litter - - - - Dumpsite - - - - Recovery - - - - Sorting - - - - Incineration (neg) - - - Paper reprocessing - (neg) - - Total (tabulate on a per bag basis!) Results are sensitive to assumed recycling rate.

18. 5) Scoring: Impact assessment Must decide (and report) how impacts are weighted. Energy alone? Atmospheric pollution? Waterborne pollution? A specific pollutant? Could take economic approach and assign a dollar value for each amount of each pollutant emitted.

19. 0.6 % 19.4 % 6) Analysis (the really interesting part) Comparison of energy efficiency of paper versus plastic bag production1. 1 Paper bag: wood 550 kJ Petrol 500 kJ Coal 350 kJ Other 280 kJ Total 1680 kJ 2 Plastic bags: nat gas 990 kJ Petrol 240 kJ Coal 160 kJ Other 80 kJ Total 1470 kJ 1. Franklin Associates, Ltd. 1990

20. Pollution type 1 Paper bag 2 Plastic bags Solid waste 50 g 14 g Atmospheric 2.6 kg 1.1 kg Waterborne 1.5 g 0.1 g 6) More analysis At current recycling rates…. 1. Franklin Associates, Ltd. 1990

21. How are Life-Cycle Analysis results used? • Process development • Engineering decision-making • Policy decision-making • Product comparison • Eco-labels Visit the Institute for Lifecycle Energy Analysis for more examples http://www.ilea.org/

22. Economic input-output models are helpful in conducting a LCA. • Economy is divided into multiple sectors • Economic activity in each sector has unique effects: • Electricity & energy use • Pollution [conventional, greenhouse, fertilizer] • OSHA accidents • Water use • Economic activity in any sector may initiate activity in other sectors e.g. consuming a glass of milk involves ore use…

23. Homework Problem: Identify and analyze a decision today’s consumers frequently make between two competing alternatives. Use the online economic input-output life cycle analysis tool (www.eiolca.net) to supplement your study. Write a concise two-page summary (including graphics and references) to describe what you did, and remark on your findings.

30. - Be sure to normalize your results! E.g. a $1000 computer has 1/1000 of the impact as $1,000,000 economic activity - Please choose an interesting topic !