We humans are subject to the same laws of nature that govern the rest of the universe. If this were not true, there would be no concern about sustainability. We could simply solve any problem we create and find a substitute for any resource we use up—which is precisely what some critics of sustainability assume. Among the laws of nature are the basic laws of physics, such as those related to gravity and motion, electricity and magnetism, time and space relativity, and thermodynamics. We may not understand or respect the laws of nature, but we can’t avoid their consequences. No matter how adamantly we may deny the law of gravity if we drop something heavy on our foot, we will feel the pain. If we defiantly stick a paperclip into an electrical outlet, we will be jolted back to reality.
Questions of sustainability are rooted in the laws of thermodynamics. The first law of thermodynamics states that energy can neither be created nor destroyed. So, it might seem that we could simply use and reuse energy over and over again to meet our needs. However, the second law of thermodynamics states that whenever energy is used, it inevitably changes in form, specifically it changes from more useful to less useful forms of energy. In fact, it is the natural tendency of structured, organized, and concentrated forms of energy to disintegrate, disorganize, and disperse that enables energy to perform work or do something useful. But after each use of energy, it becomes less useful. Waste is either useless, or unusable, energy or something that renders energy useless, or currently unusable. Whenever energy is used to do anything useful, some of its usefulness is inevitably lost. This is the crux of the physical “law of entropy.”
This is what Einstein’s famous E=MC-squared formula is all about. E is energy, M is pure matter, and C is the speed of light—which is a really big number. The energy contained in matter can be released to perform useful tasks, such as when coal is burned to generate electricity or gasoline explodes in an engine to move an automobile. Energy can also be used to create new matter or to restore the usefulness of used energy by other means. However, the energy required to restructure, reorganize, reconcentrate, and restore the usefulness of energy is no longer available to perform work. No matter how efficiently we use or reuse energy, some of its usefulness is inevitably lost.
These laws of thermodynamics were named for the natural tendency of heat to flow from hotter objects into cooler objects. However, they apply more generally to energy and the usefulness of energy to humans. Heat is but one example of a more highly structured, organized, concentrated form of energy that has the potential to perform useful work, as it follows its natural tendency to disintegrate, disorganize, and disperse as it flows from hotter to cooler objects. The steam engine is a classic early example of the potential usefulness of heat released from wood or coal as a source of useful energy. Food also is a highly structured, organized, and concentrated form of energy that disintegrates, disorganizes, and disperses into the cells of the human body during the processes of digestion.
The sustainability of human life on Earth ultimately depends on sustaining the usefulness of energy. Our food, clothing, lodging, transportation, education, health care, and other necessities of modern life all require energy to create, energy to use, and even energy to appreciate. Our brain requires something like 20 percent of the energy needed to fuel our bodies.
If the earth was a “closed system,” the usefulness of all energy in the earth’s biosphere eventually would be depleted. Fortunately, the earth receives a daily infusion of new energy from the sun—solar energy. The potential sustainability of life on Earth depends on our ability to capture and store enough useful solar energy to offset the inevitable loss of useful energy to entropy. Fossil energy is simply solar energy that was stored in the earth millions of years ago. Its usefulness eventually will be depleted and would take millions of years to restore. Other sources of energy, including nuclear energy and geothermal energy, are either limited in potential or pose threats to the livability of the environment, as does our continued reliance on fossil energy.
The only sustainable source of energy for humanity is solar energy. More specifically, the sustainability of human life on Earth depends on the ability of green plants and algae to use the process of photosynthesis to transform solar energy into biological energy. We are biological beings. We can transform solar energy into electricity using windmills and photovoltaic cells. But it takes humans to build windmills and photovoltaics, and we can’t fuel the human mind or body with electricity. We can capture radiant energy directly from the sun or mechanical energy from falling water, but we can’t survive physically without biological energy. Sustainability depends on the ability of living, biological ecosystems to sequester sufficient biological energy from the sun to offset the biological energy ultimately lost to entropy.
To sustain human life on earth at anything approaching the scale of today’s global society, we must create a regenerative agri-food economy. A sustainable regenerative agriculture must be capable of sequestering enough solar energy to meet current human needs, plus continually regenerate and renew the usefulness of enough energy to meet the needs of future generations. Regenerative farming systems that sequester carbon or restore soil health will not be sustainable unless they sequester sufficient solar energy to maintain the health and productivity of the ecological and social systems that must sustain their productivity. Regenerative agriculture is ultimately about continually capturing and storing enough solar energy to meet the biological needs of the present without depleting or permanently damaging the natural or human resources needed to meet the needs of the future.
The current industrial agri-food system relies heavily on fossil energy to offset its inevitable and continual disintegration, disorganization, and dispersion of useful energy. The food system in total uses nearly 20 percent of all fossil energy used in the U.S. with agricultural production accounting for more than 20 percent of that total. Commercial fertilizers, particularly nitrogen, account for more than 30 percent of fossil energy use in agriculture. Field machinery and irrigation account for another 30 percent.
Increased reliance on fossil energy is largely responsible for the increases in productivity associated with agricultural industrialization. Back in the 1940s, U.S. farms produced more than 2 calories of food energy for each calorie of fossil energy. By the early 2000s, industrial agricultural systems required about 3 calories of fossil energy at the farm level to produce each calorie of food energy.
Industrialization is an efficient system of extracting useful energy from nature and society, but it does nothing to restore the usefulness of the places and people it extracts from and exploits. The laws of thermodynamics are but one example of how the current industrial agri-food system fails to respect the basic laws of nature and thus is not sustainable.