ENGR 482 Lecture 22

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guest lecture by Dr. Robin Autenrieth

Practicing Sustainable Engineering

Sustainability Concepts

sustain — to cause to continue (as in existence or a certain state, or in force or intensity);

(1987) "Our Common Future" (aka Brundtland Report):

• Sustainable development: Develoment that meets the needs of present without affecting ability of future.
• "State of technology and social organization on environmental resources and by the ability of the biosphere to absorb effects of human activity.

Incentive for education: Sweeping classrooms across nations (+80%) Incentive for business: marketing tool, promote "green research"; also following legislation

The Commons

Tragedy of the commons: Decisions that maximize individual benefit can maximize collective costs

Best described as resource exploitation.

Externalities: the costs that others pay

Natural Capital

"Raw materials" from nature.

Some are renewable, some are not.

Natural Captial can be liquidated to "increase" short-term revenue, but long-term production is diminished.

Can we replace Natural with Human-Made Capital?

• often not possible
• when possible, it's expensive

Resource Fungibility

• Classical economics; resources can be subsituted through "exchange rates"
• Bald eagle is not fungible ('Merica!)
• "strong" vs "weak" sustainability (recycling is weak because of the extra energy and effort required)

System Boundaries

Engineers like closed boxes around systems, but systems can be very large and complex

Materials and Enegry Balance

revenge of 1^st law of thermodynamics

• account for fluxes of mass and energy across system boundaries
• Redefine waste streams as inputs to other systems (sell it to someone else)

Entropy

revenge of 2^nd law of thermodynamics

• minimize entropy to maintain sustainability
• energy is required to do this
• implies sustainability is impossible

Time-Horizons and Life Cycles

Sustainable development is all about future generations, we should consider what will be left to future generations

Equity

• sustainable development is an ethic based on inter-generational equity
• Is intra-generational equity also important?
• Is "environmental justice" just as important?

Life Cylcle Assessment

Quantitative measure for evaluating impacts associated with a product or service throughout its "cradle-to-grave" lifetime

1. Inventory analysis: inputs and outputs
2. Assess impact of inputs and outputs
3. Interpretation of results

Measuring Sustainability

• Equity
• Energy use/savings
• Resource use/savings
• Pollution generated/avoided (common tool)
• Quality of Life
• Economic value

Innovation

lots of challenges created by past actions (and present actions)

• Alternative Energy Sources
• New Engine Design
• Water usage (low flow toilets, xeriscapes, gray water reuse)