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Eco-audits and Tools

Eco-audits and Tools. Eco-audit. Fast initial assessment Look for “hot spots” with greatest impact material, manufacture, transport, use, disposal Often one phase contains 80% of impact. Eco-audit. Main purpose is COMPARISON This allows alternate designs to be investigated.

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Eco-audits and Tools

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  1. Eco-audits and Tools

  2. Eco-audit • Fast initial assessment • Look for “hot spots” with greatest impact • material, manufacture, transport, use, disposal • Often one phase contains 80% of impact

  3. Eco-audit • Main purpose is COMPARISON • This allows alternate designs to be investigated

  4. Inputs to an Eco-Audit • Bill of materials • Process Choice • Transport Requirements • Duty Cycle • Disposal Route

  5. Additional inputs • Data for embodied energies, process energies, recycle energies, carbon intensities • Use this data to match with first set of user inputs

  6. Outputs • energy and/or carbon footprint of each phase of life • bar chart or table, as desired.

  7. USER INTERFACE • Bill of materials • Shaping processes • Transport Needs • Duty Cycle • Disposal Route • LOOKUP TABLES • Embodied energy/CO2 • Process energy /CO2 • Transport energy /CO2 • Conversion efficiencies ECO-AUDIT TOOL • TABULAR DATA • Life-phase energy • Data used • Calculation steps • Component breakdown • ...

  8. Bottled Water - example • 1 liter PET bottle with PP cap • bottle weighs 40 grams • cap weighs 1 gram • Both are molded and filled with water in France. • Filled bottles transported to London (550 km in 14 ton truck) • Bottles refrigerated for 2 days (average) before being served at restaurant • “Green” restaurant - 100% recycling. • Let’s use 100 bottles for our basis of study. This uses 1 cubic meter of refrigeration.

  9. Bottled water BOM & Mfg.

  10. Bottled water - transport • Traveling 550 km; and 100 bottles weight 104.1 kg • 14 ton truck uses 0.9 MJ/ton-km • 0.9 * 550* 104.1/1000 = 51.5 MJ

  11. Bottled water - use • Bottles are refrigerated for an average of 2 days. • We can find that energy efficient refrigerators use 10.5 MJ/m3/day (and 13.5 MJ/m3/day for freezing) • 100 bottles use up 1 cubic meter of space, so • 21 MJ for 2 days of refrigeration • Electrical refrigerator, so must divide by efficiency (36%) -> 21/0.36 = 58.33 MJ

  12. Bottled water - disposal • In general, we have 5 options: • Landfill • Incineration • Recycling • Re-engineer • Re-use

  13. Bottled water - disposal • Our restaurant has excellent recycling. Recycling actually contributes negative energy/carbon to the calculations. • We get 35 MJ/kg back from PET recycling, and save 0.98 kg/kg CO2. • We get 40 MJ/kg from PP and 1.15 kg/kg CO2. • 4 kg of PET and 0.1 kg of PP -> 4*35+0.1*40 • -144 MJ from recycling.

  14. Summary

  15. Bottle - Energy

  16. Bottle - Carbon

  17. Energy breakdown

  18. Carbon Breakdown

  19. Case Study:Electric tea kettle • 2 kW kettle • Made in SE Asia, • transport to Europe (12,000 km) • boils 1 liter in 2 minutes, • used 2x per day, 300 days/year • lasts for 3 years • sent to landfill at end

  20. Bill of Materials

  21. Other phases • Transport: Air freight (8.3 MJ/ton-km) • 8.3 * 12,000 * 1.35/1000 = 134.5 MJ • Usage: 3 years, 300 days/year, 3 minutes per day, twice per day • 90 hours * 2kW = 180 kWhr = 648 MJ • Electric, so divide by efficiency to get actual usage (UK has 40% efficiency) • 648/0.40 = 1,620 MJ • Land fill - 0.2 MJ

  22. Overall

  23. Tea Kettle • What is best choice of action?

  24. Car Bumpers • Bumpers provide energy absorption for passengers. Early bumpers were steel with chrome plating -- they have changed over the years, now typically plastic coatings. • Let’s compare a steel bumper to an aluminum one (underlying structure - not exterior skin).

  25. Bumpers • Steel - 35 MJ/kg • Aluminum - 210 MJ/kg • BUT - we use less weight of aluminum for the same performance • Steel - 14 kg • Aluminum - 10 kg

  26. Bumpers • The car has to move the bumper around when it moves. (F=ma). Gasoline powered cars use about 2.06 MJ/ton-km to move things. • If the car drives 25,000 km per year and lasts 10 years then we have 250,000 km. Multiply by the weight of the bumper and we get the energy of usage.

  27. Bumpers

  28. Bumpers

  29. Bumpers • The benefit to Al bumpers came primarily from the usage - the miles driven. • What if we assumed a different number of miles per year? • Or a different number of years that the car is kept? • The embodied energy is a combination of a fixed amount (material + manufacture) and a variable amount (usage - based on miles).

  30. Family Car -use vs materials • Argonne National Labs has a model (GREET) to evaluate energy and emissions for automobiles. • They looked at many cars, but let’s look at a typical conventional ICE car compared to a lightweight ICE car. • The light weight car weighs 39% less than the traditional.

  31. Lightweight • So it is worse for the environment to make a lightweight car. • But, as we know transportation energy is significant. We should use less energy driving a lighter weight car. • Conventional gasoline cars use 2.06 MJ/ton/km • So the transportation energy will be:2.06 * mass * km driven

  32. Usage • If we assume 15,000 mi/year and the car is kept for 5 years, then we can compare use energy: • It’s not even close for 5 years - these are reported in GJ (1,000 MJ)!

  33. Payback • Let’s consider a 2 kW wind turbine. • We can do the calculations of materials, manufacturing, transportation and usage based on a detailed description of the product. • Usage energy will be maintenance for one year.

  34. Wind Turbine

  35. Wind Turbine • The turbine is rated at 2MW. • That means at optimum performance it generates 2MW (wind blowing at speed). Let’s say it only gets 1/4 of that as a realistic estimate. • So we have 0.5 MW * 365.24 days * 24 hrs/day = 4,383 MW-hrs = 15,779,000 MJ in one year

  36. ROI • We invested 19.7 TJ in making and installing and maintaining the turbine. • We get back 15.8 TJ each year. • 19.7/15.8 = 1.25 • So it takes 1.25 years (15 months) to get back the invested energy. • It is rated for 25 years, so we get back 20 times the invested energy. • But, it takes about 2,000 of these to replace a single coal plant

  37. Exercise • 1,700 W steam iron. • Weighs 1.3 kg • Heats up on full power for 4 minutes then used for 20 minutes on half power. • 5 year life, after which it hits the landfill.

  38. Bill of Materials

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