Month: January 2013

Life-time battle

163-6306_IMGLife is a constant battle against entropy.  All living things are well-ordered structures with low entropy (degree of disorder) and the second law of thermodynamics demands that entropy levels are always trying to increase.  Animals fight this tendency by eating low entropy plants (or other animals), breaking them down to release entropy, thus satisfying the second law, and retaining low entropy components, i.e. highly-ordered and high energy molecules such as glucose.  If we stop eating, our bodies start to disintegrate and we die – entropy wins as the molecules of bodies are dispersed.

Plants use sunlight to fight the entropic battle.  In photosynthesis, low entropy solar energy converts carbon dioxide and water  to oxygen and glucose with the creation of entropy in the form of dispersed heat.

Food waste

korea cafeteriaIt has been reported recently that there are more people suffering from obesity in the world than from malnutrition (http://www.ifrc.org/en/publications-and-reports/world-disasters-report/wdr2011/).  This might suggest that global society has a major distribution problem to solve and that current approaches are failing.  This is a tentative conclusion supported by another recent report which estimates that half of global food production is wasted (http://www.imeche.org/knowledge/themes/environment/global-food).  Some agricultural production never reaches the distribution system and rots in the fields, while some is disposed of untouched by end-purchasers.  Presumably end-purchasers throwing away uneaten food are not starving and probably a high proportion of them are obese.

The second law of thermodynamics demands that there must be waste in all processes, so we can never reduce the wasted food production to zero but 50% wastage seems high and perhaps implies we some way to go before population growth is limited by food production (see post on ‘Two Earths’ in August 13th, 2012 or ‘Population crunch’ on September 15th, 2012).  Of course, if the majority of current food production is unsustainable then we are in trouble already.

Unavoidable junk

167-6734_IMGThe laws of thermodynamics are physical laws whose relevance extend beyond the study of engines and heat plants.  We can restate the first law of thermodynamics (conservation of energy) as ‘the quantity of matter is constant and finite’.  Matter changes both in nature and as it moves through the economic system; and as it does so, its intrinsic properties change rendering it less useful and usable, thus requiring more and more resources to make it useful again.  This last sentence is a form of the second law of thermodynamics.  Very useful (low entropy) goods, such as iron ore and fossil fuels, eventually produce less useful (high entropy) matter, such as piles of junk cars in scrap-metal yards and greenhouse gases, as they move through the economic system.  In our current western life-style, we are all contributing to the generation of vast piles of junk; we are hooked on it; we are all ‘junkies’.

In the paragraph above, I have plagiarised the 2009 report entitled ‘The New Sustainable Frontier’ mentioned in the previous posting on this blog [http://www.gsa.gov/graphics/ogp/2009_New_Sustainable_Frontier_Complete_Guide.pdf ].  However, similar ideas were expressed by Handscombe and Patterson in their 2004 book entitled the ‘Entropy Vector’ [http://www.worldscientific.com/worldscibooks/10.1142/5365 ].  They paraphrased the first and second laws of thermodynamics as ‘you can’t have something nothing’ and ‘you can’t have it just anyway you like it’.

Renewable energy?

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Old Faithful

‘Renewable energy’ is an interesting use of words because the first law of thermodynamics tells that energy is always conserved while the second law implies that during all processes the quality or usefulness of energy is degraded.  Both energy ‘generation’ and ‘consumption’ are processes in which energy is converted from one form to another with some degradation in quality or usefulness; how much degraded energy is produced compared to useful energy or electricity in a generation process is a measure of the efficiency of the process.  Whereas in a consumption process we expected most of the energy to be degraded to the point of uselessness, often in the form of heat or noise.  So the concept of renewable energy suggests that we can somehow refresh or recover the quality and usefulness of energy degraded in consumption processes.  In practice it is not possible to refresh or renew the energy, instead we replenish it with new ‘high quality’ energy arriving from the sun.

The picture shows Old Faithful Geyser in Yellowstone National Park in the USA.

Open-world mind-set

Can we consider the world to be a closed system?  The universe surrounding the Earth is largely a vacuum so that only the occasional meteorite enters the system and gravity prevents anything leaving, besides a rocket now and then.  Thus, it is not unreasonable to approximate the Earth as a closed system but it is not an insulated system because there is a continuous transfer in and out of energy derived from the sun.  There is a nice summary diagram of this energy transfer in a paper by Kiehl and Trenberth (1997) [http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html].  The premise of the movement towards sustainability is that our world is closed system which thus contains finite material resources although there is a continuous supply of energy into the system from the sun, which provides us with the concept of ‘renewable energy’.  At the beginning of the industrial revolution our consumption of the world’s resources seemed miniscule compared to the available resources, which appeared effectively infinite and led to an ‘open-world’ mindset, i.e. an approach to living that assumed a continuous supply of energy and material into an open system.  Today, our consumption of resources has grown enormously and we close to exhausting some supplies, which is typified by the fact that the average person on Earth uses 5.7 acres of biologically productive land to supply resources and absorb waste, but only 4.7 acres/person are available for the current global population.  To achieve sustainability we need to switch from an open-world or open-system mind-set to a closed-world or closed-system way of thinking.  A report entitled ‘The New Sustainable Frontier’ published in 2009 by the US GSA Office of Governmentwide Policy [http://www.gsa.gov/graphics/ogp/2009_New_Sustainable_Frontier_Complete_Guide.pdf] is much more eloquent than me on this subject.  See also my ‘Two Earths’ post on August 13th, 2012.