Quo vadis energy sustainability

Analysis of the sustainability of any system is understood to examine the system performance from the perspectives of its impacts on three domains: environmental, economic, and societal. For energy systems, it is evident now that net greenhouse gas (GHG) emission concern has become the dominant driver for sustainability consideration. All western countries and most in the developing worlds have pledged to reduce GHG emissions in order to reverse potential ill effects of warming of the planet. Not all energy systems emit GHG, but the overall portion of the global energy use of those systems that are GHG-neutral currently is no more than 20%. The important non-fossil energy systems with no net-positive GHG emission are nuclear, biomass and wastes, hydro, wind, solar, and geothermal. Oil (34%), coal (25%), and natural gas (21%) not only constitute the main sources of the world’s energy, but are also believed to continue to maintain similarly dominant position until about 2030, according to Energy Information Administration, as shown in Fig. 1 (EIA 2009a). To satisfy proclamations of draconian cuts in CO2 emissions by most western nations by this date, renewable and non-fossil energy systems would have to be rapidly developed and provided affordably. A recent EIA estimate showed that renewable energy production worldwide in 2025 could potentially reach greater than 200 quadrillion BTUs, which is double the entire U.S. energy use per year today. Even in that scenario, the total fossil energy use is not seen as substantially decreasing in absolute term. As a result of the continued and increasing use of fossil fuels, carbon dioxide emissions will keep on increasing, though, as Fig. 2 shows, the emissions from the OECD nations will have stabilized by 2030, and most of the GHG emissions will come from the developing economies (EIA 2009b). Carbon dioxide emission has become the main focus in debates on energy sustainability because most of these are derived from non-renewable fossil fuels used in power generation (coal and natural gas) and transportation (petroleum), and thus are deemed to be undesirable from global warming viewpoint. Even though over the longer term these are depletable resources, currently there is no shortage of these fuels. The supply and price of these fuels are largely controlled by the international cartel, and more sources are periodically discovered, adding to the recoverable reserves. The recent surge in world prices of fossil fuels resulted mainly from market disruptions and inevitable speculations in the futures market. One of the sustainability criteria any energy resource has to meet is whether we are keeping enough of that resource for the future generations. Fossil fuels do not have to meet this criterion because the resulting carbon dioxide emitted to the atmosphere is believed to do irreparable harm to all inhabitants of this planet because of global warming. This makes the case for drastically reducing the use of these fuels, while developing non-fossil routes to energy to power worldwide development. The U.S. National Research Council, in Grand Challenges for the Chemical Industries, foresees the transition to non-fossil fuels consummating by the turn of the 22nd century (NRC 2005). Negotiations have been ongoing among the nations of the world since the signing of the Kyoto protocol on how to achieve the goal of stabilizing atmospheric CO2 at 500– 550 ppm—without success of any kind. Given the economic status of nations, self-interest differs from one another and that is reflected in their policy practices. The S. K. Sikdar (&) National Risk Management Research Lab/USEPA, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA e-mail: sikdar.subhas@epa.gov