V. Smil, Energy in Nature and Society: General Energetics of Complex Systems

Abstract

Energy is a central concept in physics. Thus I was particularly drawn to this new book by an author who, in the last 30 years, has written 20 books, half of which have the word ‘‘energy’’ or ‘‘energetics’’ in their titles. Vaclav Smil, a Distinguished Professor at the University of Manitoba in Canada, has written on energy in the environmental context broadly, and specifically on agriculture, the biosphere and biomass, and in the developing world and China. Here, with erudite quotations Professor Smil provides an excellent, balanced overview of both the sources and the uses—by the human species—of different forms of energy on our planet. The fundamental aim of this book is ‘‘to produce a comprehensive, systematic, revealing (and hence interdisciplinary and quantitative) treatment of all major aspects of energy in nature and society’’. This most ambitious aim is definitely achieved by the analyses and syntheses presented. The first two chapters adopt a historical and physics approach to the concept of energetics, contrasting quantities such as power, or energy flow (in W or J/s), power density or rate of energy flow per unit area (in W/m), and specific energy or energy intensity (in J/kg). The conversions between different forms of energy—chemical, electrical, electromagnetic, gravitational, kinetic, nuclear and thermal—are explained. This discussion is highly relevant in the light of today’s discussions on biofuels. Energy fluxes are explored, ranging from that due to solar radiation (peaking at a wavelength of *500 nm) to terrestrial radiation (peaking at 10 lm), meridional heat transport in the ocean, tornadoes, geothermal processes, volcanoes and earthquakes. That ‘‘sets the stage for reviewing both the bioenergetic fundamentals and the specific and ecosystemic peculiarities of the plant and animal kingdoms’’. Chapter 3 is on photosynthesis, the bioenergetics of primary production in bacteria or green plants. Phototrophs are organisms which obtain energy from sunlight for the synthesis of organic compounds. They require oxygen in the atmosphere to remove carbon dioxide from the atmosphere, i.e. in order to assimilate (or ‘‘fix’’) carbon. The complicated enzymatic chemical reactions of ‘‘net primary productivity’’ are explained. Trees store *20 MJ/kg