MATERIALS and the ENVIRONMENT

1. MATERIALS and the ENVIRONMENT

2. Worldwide Consumption of Hydrocarbons and Engineering Materials

3. Most materials are being consumed at a rate that is growing exponentially with time Based on current data, steel consumption doubles every 18 years while polymer consumption doubles ever 14 years At a global growth rate of just 3% per year we will mine, process and dispose of more ‘stuff’ in the next 25 years than in the entire history of human engineering

4. EXAMPLE: Silver Production

5. EXAMPLE: Cars in China

8. Energy and materials are consumed at every point in a products life-cycle Ore and feedstock are mined and processed to yield a material This is manufactured into a product that is used, and then discarded or recycled Life-cycle assessment is used to evaluate the eco-impact throughout all cycles of a products life, from extraction of the ore to possible recycling Carbon dioxide and other emissions are collectively known as environmental ‘stressors’ which LCA attempts to identify and quantify

9. Used to asses embodied energies The processing energy Hp is the energy used to shape, join, and finish 1 kg of the material to create a component or product Inputs to this analysis involve the processing energy and the material’s embodied energy The output is the energy committed per part produced

10. The embodied energy Hm (MJ/kg) of a material is the energy that must be committed to create 1 kg of usable material The CO2 footprint is the associated release of CO2 in kg/kg Energy consumption and CO2 emissions are nearly equivalent when evaluating the eco-impact of a product

11. End of life potential of a product Ability to be recycled into the product from which it came Ability to be down-cycled into a lower-grade application Ability to be biodegraded into usable compost Ability to yield energy by controlled combustion Ability to be buried as landfill Once a material is released to the outside world, its recyclability decreases – the material can be processed or joined with other parts, painted, or subject to various contaminants – to reuse it, it must be collected, separated from other materials, identified, decontaminated, chopped, and processed

13. Steps required to recycle PET, each one consuming energy For polymers such as PET, about 50% of the embodied energy can be saved from recycling – this number can be much higher for certain metals but can also fall to zero for other materials

15. Total energy use of a product includes the material’s embodied energy and energy of processing as well as use-energy, energy associated with maintenance, and energy of disposal The products in the top row all consume energy as an unavoidable consequence of their use The products in the bottom row depend less on energy, but are material intensive

18. When compared per unit mass, metals, particularly steels, demand much less energy When compared on a volume basis, the ranking changes and polymers lie lower than metals

19. More appropriate charts for embodied energy compare Hm per unit of function

20. The figure is the equivalent of the yield strength vs. density chart used for strength-limited designs while incorporating the eco-impact of the material

21. An environmentally responsible design begins by identifying which phase of the life cycle of the product makes the largest impact

22. The eco-impact of the use phase of energy-using products has nothing to do with a materials embodied energy – often, minimizing Hm may have the opposite effect on use energy – for applications such as car components, weight is a critical property as reduced weight leads to reduced fuel usage

23. Crash barriers are of two types – those that are static and permanently placed on highways and those that move such as the fender of a vehicle The dominant phases of the static barrier is the embodied energy of the material and the processing energy associated with its manufacture The fender is part of the vehicle and adds to its weight – its dominant phase is its use-energy as any added weight causing a decrease in fuel efficiency will outweigh its embodied and processing energies

24. The objective of the static barrier is to minimize the embodied energy while meeting constraints on strength The material index for the static barrier As embodied energy is not critical for the car fender, the best material choice is based on minimizing mass while meeting a strength constraint

25. A corporation’s ultimate success and health should be measured not just by the traditional financial bottom line, but also by its social-ethical and environmental performance

26. Manufactured capital • Industrial capital, institutions, roads, built environment, financial wealth (GDP) • Human capital • Health, education, skills, technical expertise, accumulated knowledge, happiness • Natural capital • Clean atmosphere, fresh water, fertile land, productive oceans, accessible minerals and fossil energy

27. Competing articulations of sustainable technology conflict The Motivation provides the Prime Objective

29. Figure 20.20

32. SUMMARY • Selecting materials to meet environmental objectives involves: • Identify phase of life with biggest energy requirement: • Production / manufacture / usage / disposal • Need lots of data to do this well • Eco-Design is one aspect of sustainable development. • Sustainable development involves: • Clean energy • Responsibly sourced materials • Recovery and reuse of materials at the end of product life • An economy that generates sufficient wealth to provide for education, health and industrial infrastructure • Benefit society as a whole, and not be something for just a privileged few