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Sustainability

Sustainability. Feedback Loops Closed Systems Easter Island’s Ecology Crash The Role of IE in Sustainability. Goals for today . Draw and analyze basic influence diagrams – positive and negative feedback.

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Sustainability

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  1. Sustainability Feedback Loops Closed Systems Easter Island’s Ecology Crash The Role of IE in Sustainability

  2. Goals for today • Draw and analyze basic influence diagrams – positive and negative feedback. • Understand the story of Easter Island’s ecological crash as a positive feedback loop in a closed system • Understand principle of sustainability • See why IE will help; links to more info; ideas for projects

  3. System Dynamics • Another descriptive model • Gives qualitative predictions and insights • Software tools exist (STELLA) for more quantitative predictions • Industrial Dynamics, by Jay Forrester (the classic reference) • Popular book: The Fifth Discipline by Peter Senge

  4. Influence Diagrams: Core Concepts • Cause and Effect thinking, Influence or Causal Loop Diagrams • Feedback • Positive Feedback • Negative Feedback • Delay in Feedback Loops

  5. Cause and Effect • Draw an arrow from cause to effect • ``Influence’’ or ``affect’’ may be a better term than “cause.” • Examples

  6. Influence Diagrams • Place a “+” or a “-” at the arrow to indicate the kind of influence + means: the more of one, the more of the other (or less…less) - means: the more of one, the less of the other (or less…more)

  7. Feedback Loops • Any directed cycle is afeedback loop • The arrows must take you back to where you started • Feedback makes systems complicated! • Examples

  8. Principle: the most important causal influences are those that are within feedback loops

  9. POSITIVE Even # of - signs Amplifying Reinforcing Growth, but also Decline Unstable NEGATIVE Odd # of - signs Balancing Stabilizing Often good! Stable equilibria Two Kinds of Feedback

  10. Feedback Examples • A pencil falls • Standing on one foot

  11. Delay • Taking a shower • Carrying a cup of coffee • Timing very important • Beer game, supply chains • Classic problem: when short-term influence is of one type, and long-term influence is of the other type

  12. Analysis of an argumentorHow to make a mountain out of a molehill

  13. + A’s anger A’s harshness + + B’s harshness B’s anger +

  14. Mountains out of Molehills • Whose fault is it? • “You started it” • Cause, effect, and blame are not clear in complex systems

  15. + Eat Candy Blood Glucose Level + - Hunger Level

  16. + Eat Candy Blood Glucose Level - + + Delay Hunger Level - Insulin Production

  17. Oscillations that increase in amplitude over time area danger signal

  18. Glucose and Insulin • How could nature be so stupid? • How could such an unfit system survive?

  19. Nature isn’t stupid -- We are! • 1st appearance of insulin regulation • 10,000,000-70,000,000 years ago • 1st appearance of refined sugar • 1500 to 2400 years ago

  20. + Eat Complex Carbohydrates Delay Blood Glucose Level - + + Delay Hunger Level - Insulin Production

  21. Eat Complex Carbohydrates + Delay Blood Glucose Level + + - Eat Candy + + Delay + Insulin Production Hunger Level -

  22. Natural & Man-Made Systems • Natural systems have usually evolved so that timings work well • Introduce a new element into a smoothly running system and you are lucky if timings remain good • As change rate of technology  this problem occurs more frequently

  23. Open Systems and Closed Systems Consider the earth…

  24. What does Little’s Law say about a closed system? • Little’s Law does not apply to systems with no throughput. • I = RT and R = 0 ) I = 0. Thus eventually inventory drops to 0. • I = RT and R ! 0 ) T !1. Thus inventory stays in the system forever.

  25. Easter Island:The Mystery

  26. thanks to Carl Anderson for the beautiful photos The Moral: Positive (unbalancing) feedback loops in a closed system mean disaster

  27. Earth Island Is the Earth suffering from the same destructive patterns as Easter Island?

  28. Frightening Facts • 180 million tons of trash/year in U.S. • 50% of topsoil in U.S. lost this century • 25 billion tons/year worldwide • Everglades extinct? • Loss of species • frogs: 1/3 or more • we save mountains, not lowlands

  29. “Every natural system in the world today is in decline” • Water, aquifers • 20 billion gallon/year deficit in groundwater • Ogalala Aquifer dry in 30-40 years at present extraction rates • Fertility rates • Global Warming: North pole, Alaskan towns • Pesticides: 4.1 billion tons/year, 25 million deaths • Equilibria: ozone, everglades, warming

  30. Understanding Systems Problems • Tragedy of Commons. • Example: whales and the IWC • Example: strip mining the ocean floor, where there is a new species every square meter. • Limits to Growth • Example: Human Population, now over 6,000,000,000 • Transportation Engineering: • Building more highways does not reduce traffic problems. (Why?) It increases oil usage and pollution.

  31. Earth Island: Solutions Industrial Engineering & The Environment

  32. Sustainability The idea: Could we continue our current activities indefinitely? “But really, this cannot go on indefinitely, can it? Does anyone rationally think it can?” --Ray Anderson

  33. Why IE & Sustainability? • IE is all about flow systems; sustainability is all about balancing flows. • IE is all about cost-effectiveness. We will never achieve perfect sustainability. To make progress, we must find the good bang-for-buck ideas.

  34. Assessing Systems • A production process can not always be evaluated in isolation, but must be evaluated in situ, as part of a system • IE methods and approaches can help in the evaluation of systems • ECO-DESIGN by Ab Stevels (Professor at Delft University and Senior Environmental Advisor at Philips Consumer Electronics Environmental Competence Centre)

  35. Pollution Prevention Idea: instead of treating waste, don’t produce it. • Move the environmental solution upstream in the production process,just as we move quality concerns upstream. • Role of I.E.s

  36. The Logistics of Recycling and Take-Back • Transportation is usually a make-or-break cost in recycle and take-back • “Reverse Logistics” differs from traditional supply-chain and distribution logistics • Take courses from Dr. Ammons • Do a project

  37. www.sustainable.gatech.edu • ISTD: Institute for Sustainable Technology and Development • lectures and events • listserv • library • recycling info • primer on sustainability by Carol Carmichael

  38. Sustainability at Georgia Tech • We are one of the leading institutions • Georgia Tech mission statement: • “…Georgia Tech seeks to create an enriched, more prosperous, and sustainable society for the citizens of Georgia, the nation, and the world.” • Consider doing a sustainability project for 4104. Example: water and sewer costs will triple in Atlanta. That means clients!

  39. Policy Issues • Can we tax resource use rather than profits? • Companies and individuals don’t pay the true cost for resources consumed • Prisoner Dilemma and Tragedy of commons tell us that the rules of the game must be changed

  40. Service vs. Product • Provide services, not goods • Example: Ray Anderson’s company Interfaces leases carpet squares • Imagine buying the use of a working automobile for 12 years. Notice how this would change the incentives of the automobile manufacturer.

  41. Goals for today • Draw and analyze basic influence diagrams – positive and negative feedback. • Understand the story of Easter Island’s ecological crash as a positive feedback loop in a closed system • Understand principle of sustainability • See why IE will help; links to more info; ideas for projects

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