(630b) Issues On Energy Sustainability: Consumption, Efficiency, and Environmental Impact

One of the more important challenges in achieving sustainability is how to meet the energy consumption needs of a growing human population in the face of increasing economic prosperity.  In this talk, we present a very simple but rigorous procedure for exploring the relationship between energy consumption, environmental impact, human population, gross domestic product, and energy efficiency.  The underlying theory basically assumes that energy use increases with time in proportion to two factors: gross domestic product and human population.  Other assumptions are that energy use has a non-zero impact on the environment and decreases only with energy efficiency.  This approach allows us to pose and evaluate: (1) the limitations given the known behavior of societies and economies, practical technology, and the Laws of Thermodynamics and (2) possible pathways to sustainability.  The goal is essentially to look for a way to meet expected energy consumption requirements without increasing the environmental impact beyond that seen in an appropriate reference year.  We have chosen the year 1977 as our reference year because it is the year when the combined ecological footprint of the human population world-wide was equal to the biocapacity of the Earth.  That is, the capacity of the Earth was able to sustain the global demand of human beings as measured by the ecological footprint.  Although we use this metric as a benchmark,  we are not suggesting that the ecological footprint is necessarily an ideal measure of environmental impact.  Rather, we use it simply as a convenient means of establishing a reasonable reference point. Based on the aforementioned assumptions, basic calculus, and published values for energy use, gross domestic product, human population, and energy efficiency over time are used to explore energy scenarios.  Because many of the sustainability issues associated with energy use, such as climate change, are global in nature, we begin with an analysis at the global scale.  Given the expected growth in World gross domestic product as well as human population growth and energy use over the next 20+ years, our results indicate that the kinds of energy-use efficiencies needed to keep the environmental impact at or below the 1977 level seem unrealistic.  From our calculations,   energy-use efficiency would need to rise to approximately 78% by 2030 to maintain the 1977 impact level.  Not only is this level nearly impossible to achieve technologically and thermodynamically, but the amount of energy consumed per unit of gross domestic product (and per capita) would need to cumulatively decrease by 1.5% to 2% per year beginning in 2012 for environmental impact of energy use not to exceed that of 1977.  Again, this will not not an easy task.   The situation, although quite grim, is not hopeless, and the feasibility of an integrated approach to managing the environmental impact of energy use using all of the aforementioned options will be further discussed.