ABSTRACT
The nations of the world are converging in health and wealth as the world grows more polluted. Navigating a path away from this unsustainable development toward sustainable development requires an understanding of the relationships between development, energy consumption, and entropy. We explore these relationships and describe the nanocosmological processes of the big bang, which are the ultimate source of the free energy that we consume. We show that the biomolecular nanotechnology of animal muscles is more efficient than internal combustion engines. We also hypothesize that an extension of the second law of thermodynamics, the maximum
entropy production principle, is consistent with sustainable values for the rate of entropy production. To see a world in a grain of sand, and a heaven in a wild flower, Hold infinity in the palm of your hand, and eternity in an hour.—William Blake, Auguries of Innocence
2.1 The Millennium Development Goals: Sustainability vs. the Other GoalsThe millennium development goals (MDGs) for the year 2015, adopted by the United Nations in the year 2000 (https://mdgs.un.org), are 1. eradicate extreme poverty and hunger; 2. achieve universal primary education; 3. promote gender equality and empower women; 4. reduce child mortality; 5. improve maternal health; 6. combat HIV/AIDS, malaria, and other diseases; 7. ensure environmental sustainability; and 8. develop a global partnership for development. Substantial but uneven progress is being made toward these goals (United Nations, Millennium Development Goals Report, 2013). Economic growth has been the most effective path toward meeting the MDGs. For example, the growth of the economies of China, India, and other increasingly wealthy countries has reduced poverty and hunger for millions of people. As poverty and hunger are reduced, maternal and child health improves, female literacy increases, and
this tends to stabilize population (Wardatul, 2002). However, as the wealth of this stable population increases, energy consumption and pollution increase. Thus, economic development helps achieve MDGs 1 through 6 but makes environmental sustainability (MDG 7) harder (Moran, Wachernagel, Kitzes, Goldfinger, and Boutaud, 2008; Togtokh, 2011). As we celebrate (or mourn) the birth of the seven billionth human inhabitant of our planet (Tollefson, 2011), our most important challenge is how to promote development to avoid poverty while
modifying development to avoid global pollution. We have no examples of increasing economic development without increasing energy consumption and CO2 emissions (Rosling, 2009, 2010, 2011; Emerson, Levy, Esty, et al., 2010), so the challenge before us is an unprecedented and difficult one (Wilson, 2002). Where is the safest passage to sustainable development in a high-population world, where the use of our oceans and atmosphere as common waste sinks (Fig. 2.1) can no longer be taken for granted (Hardin, 1968, 1974; Daly, 1996, 2005)?The factors that have historically underpinned population health gains are now, by dint of their much increased scale, scope, and intensity, undermining sustainable good health as we exceed Earth’s capacity to renew, replenish, provide, and restore. (McMichael and Butler, 2011)
Figure 2.1 Two ecospheres of different sizes (left: ~107 m; right: ~10-1 m). Both are powered by sunlight but are otherwise self-sustaining-you never have to feed them. The larger one, on the left, is thought to be less susceptible to ecological collapse because of having more diversity in life forms. However, these life forms are constrained to live in the relatively thin surface layer, one-tenth as thick as the green line. The ecosphere on the right contains only purified seawater, algae, bacteria, and marine shrimp and has been known to last ~18 years (www.eco-sphere.com/about.html). An intermediate-sized ecosphere is described in Sagan (1990). Left image: NASA, Noon in Mozambique, 7 December, 1972. An important policy debate is going on between neoclassical economists and ecological economists that explores whether
economic life on our planet is limited. Neoclassical opinion is that “there are no . . . limits to the carrying capacity of the Earth that are likely to bind any time in the foreseeable future . . . . The idea that we should put limits on growth because of some natural limit, is a profound error . . .” (Summers, 1991; Solow, 1974; Stiglitz, 1979). Ecological economists, on the other hand, are ambitiously trying to recognize and measure the environmental overheads and weigh the trade-offs between the good and bad products of economic growth (Rees, 1992; Wackernagel and Rees, 1996; Daly, 1997a, 1997b). The argument centers around two points-which aspects of the economy are knowledge based and have no identifiable limits (or limits we haven’t reached yet [Johnson, 2000]), and which aspects have thresholds beyond which growth is uneconomic and if continued will lead to ecological collapse (Rockström, Steffen, Noone et al., 2011; Diamond, 2004). Fishing is an example of the latter:
The annual fish catch is now limited by the natural capital of fish populations in the sea and no longer by the man-made capital of fishing boats. Weak sustainability would suggest that the lack of fish can be dealt with by building more fishing boats. Strong sustainability recognizes that more fishing boats are useless if there are too few fish in the ocean and insists that catches must be limited to ensure maintenance of adequate fish populations for tomorrow’s fishers. (Daly, 2005) Forty years ago, Georgescu-Roegen (1971, 1975) introduced the concept of entropy into economics (Schneider and Sagan, 2005). There has been controversy ever since about what kinds of goods are subject to the second law of thermodynamics (Daly, 1997a, 1997b). Ecological economists, such as Daly (2005), invoke entropy as the ultimate limit on sustainability: [L]ack of sustainability is predicted by the first two laws of thermodynamics, namely that energy is conserved (finite) and that systems naturally go from order to disorder (from low to high entropy). Humans survive and make things by sucking useful (low-entropy) resources-fossil fuels and concentrated minerals--from the environment and converting them into useless (high-entropy) wastes. The mass of wastes continuously increases (second law) until at some point all the fuel is converted to useless detritus. (Daly, 2005)
To understand the limits of economic growth and to chart a path between the Scylla of poverty and the Charybdis of pollution, we need to understand what sets the limits on the earth’s capacity to “renew, replenish, provide and restore.” At what point will all the fuel be “converted to useless detritus”? It is easy to run out of fuel if you don’t have a fuel gauge. A good place to begin the task of devising a reliable fuel gauge for the planet is with the laws of thermodynamics. Daly is correct when he asserts that “at some point,” all fuel will be converted to useless detritus. That is the inevitable ultimate result of the second law: dS ≥ 0. However, the “some point” is rather far in the future. The universe will reach a heat death ~10,000 googol years (10104 years) from now, when there will be no more stars to shine (Egan and Lineweaver, 2010). A “lack of sustainability” is only “predicted by the first two laws of thermodynamics” on time scales longer than a billion years. There are two sources of the earth’s capacity to “renew, replenish, provide and restore.” For the life of the biosphere (estimated to be another billion years [Caldeira and Kasting, 1992; Lenton and von Bloh, 2001; Lovelock and Whitfield, 1982]), we can count on the fusion of hydrogen in the sun and the temperature gradient between the hot interior and the cold surface of the earth (Korenaga, 2008) to supply the earth with low-entropy energy to power winds, rain, and the biosphere and naturally recycle wastes that life forms produce. The sun provides ~300 W/m2, while the heat of the earth’s interior provides ~0.1 W/m2 at the surface. The earth’s surface and the biosphere will continue to be replenished by the supply of low-entropy free energy from these two sources-driving plate tectonics that build mountains and the hydrological cycle that erodes them down and driving volcanism that replenishes the nutrients in the soils and rains that leach the nutrients out, while providing freshwater at a given rate. That rate sets the rate of sustainable extraction. Thus, for the next billion years on the earth, the second law, dS ≥ 0, is not the problem. The problem is much more immediate-the current rate of entropy increase is larger than a sustainable rate: (dS/dt)current > (dS/dt)sustainable (2.1) We are digging up and burning fossil fuels faster than nature is burying them. We are drinking and irrigating with freshwater faster than the clouds, rivers, and aquifers can supply it (Trenberth, Smith,
Qian, Dai, and Fasullo, 2007; Wada, van Beek, van Kempen, 2010), and we are mining minerals faster than plate tectonics can create new deposits. The amount of freshwater that the earth can produce is limited by the input of free energy from the sun, which evaporates surface water and drives convection cells and winds, which carry the clouds over the land, where freshwater falls as rain, recharging the rivers, ponds, aquifers, and plants (Kleidon, 2010; Lineweaver, 2010). As is the case for the fish in the sea, the highest rate at which water can be sustainably extracted is the natural rate at which the hydrological cycle, driven by the sun, can supply it. At faster rates, aquifer water levels get lower and wells get deeper. Much of civilization (farms, desalinization plants, oil refineries, modern fisheries, and mining) is based on speeding up the natural production of food, water, and almost anything that can be made with electricity. 2.2 Energy Conservation, Entropy Increase
Understanding the role played by the first and second laws of thermodynamics can help us measure the carrying capacity of natural recycling and the price of speeding it up or overloading it (Emerson, Levy, Esty, et al., 2010). Understanding energy and entropy can help resolve the tension between development and global pollution-or at least help us think less myopically about the trade-offs. Energy conservation (first law) and entropy increase (second law) are the unifying concepts that connect gravitational collapse to nuclear fusion, fusion to sunlight, and sunlight to food, to the carrying capacity of the earth and to sustainable development. First, let’s review the sources of energy. Figure 2.2 shows the most familiar sources of energy in the universe. As mass falls into a gravitational well (Fig. 2.2A), its gravitational potential energy can be used to do work (e.g., hydroelectric power from dammed rivers and geothermal energy left over from accretion of the earth). As protons and neutrons (Fig. 2.2B) fall deeper into a nuclear potential, they release energy in the form of gamma ray photons, which emerge as visible photons from the photosphere of the sun. These photons power the hydrological cycle, ocean currents, solar cells, windmills, and phototrophic life
forms. For example, in cyanobacteria and plants, solar photons excite electrons into higher-energy states, dissociating water and CO2 to produce carbohydrates and free oxygen. We aerobic animals breathe oxygen and oxidize these high-energy electrons down into lower-energy states (DE in Fig. 2.2C). We live off this DE.
