Exergy, environment and sustainability Mechanical Engineering - - PowerPoint PPT Presentation

Mechanical Engineering ME562Sustainable Energy: an Exergy Analysis

ME 562: Sustainable Energy – an Exergy Analysis Spring 2014

Exergy, environment and sustainability

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Energy and economy: the 1970s

“Tonight I want to have an unpleasant talk with you about a problem unprecedented in our history. With the exception of preventing war, this is the greatest challenge our country will face during our lifetimes. The energy crisis has not yet

• verwhelmed us, but it will if we do

not act quickly. It is a problem we will not solve in the next few years, and it is likely to get progressively worse through the rest

• f this century.

We must not be selfsh or timid if we hope to have a decent world for our children and grandchildren. We simply must balance our demand for energy with our rapidly shrinking resources. By acting now, we can control our future instead of letting the future control us. ...” Jimmy Carter, April 18, 1977

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Oil price vs. GDP

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What about the environment?

“The good Earth — we could have saved it, but we were too damn cheap and lazy” Kurt Vonnegut, from “A Man Without a Country” (2005)

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Acid rain

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Ozone depletion

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Climate change

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How do we cut GHGs?

http://www.sciencemag.org/content/335/6064/53.abstract

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What does it mean practically?

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Ouroboros and the 2nd law

Order destruction and Chaos creation

• A low-exergy (disordered)

environment is a degraded one

• Human value systems in some way are

related to order

Resource degradation

• Resources not at equilibrium with the

environment are valuable (e.g. a high- concentration ore)

• Resources with high reactivity are

valuable (e.g. oil, natural gas)

Waste exergy emissions

• Wastes with high exergy have the

potential to react with the environment

• High-exergy waste can interfere with
• ther exergetic processes

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Exergy effciency and sustainability

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Four aspects of sustainability

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Exergy path to sustainability

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Issues in renewables deployment

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Typical steam plant layout

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Energy and exergy paths