PRINCIPLES OF SUSTAINABILITY
Revised 26 September 2021
CONDENSED CHAPTER SUMMARY - see more detailed summaries under Section headings
Laws of Thermodynamics
- Humankind's survival is totally dependent on the access and use of energy in the form of food and the combination of energy and concentrated minerals in its technology.
- Energy is defined as 'the ability to do work on other bodies’ or as ‘stored work’.
- Work is said to be done on a system if that system experiences a displacement as the result of a force parallel to and in the same direction as that force.
- Heat is defined as that energy which is transferred between a system and its surroundings solely by virtue of a temperature difference
- The First Law of Thermodynamics: Energy may be transformed from one form into another, but energy is neither created nor destroyed.
- The Second Law of Thermodynamics: All physical processes proceed in such a way that the availability of the energy involved decreases.
- In a low entropy system the energy is free in the sense that it is available for producing mechanical work, whereas in a high entropy system the energy is said to be bound.
- The Law of Entropy can be state as: When all systems taking part in a process are included, the entropy S of the total system either remains constant or increases.
- An open system may exchange both energy and matter with the outside, whereas a closed system exchanges only energy and not matter with the outside.
- Contrary to being a violation to the law of entropy, life forms comprise systems that hasten the increase of entropy in the universe
- The Law of Entropy can be stated as: In spontaneous processes, concentrations tend to disperse, structure tends to disappear, and order becomes disorder.
- The First Law of Thermodynamics does not contradict the laws of mechanics, but the Second Law of Thermodynamics, the law of entropy, is in direct contradiction with the laws of classical mechanics in that the law of entropy introduces the element of an irrevocable qualitative change when systems undergo any process.
Energy Analysis & Energetics
- Energetics uses a general systems approach and circuit language diagrams to describe and analyse energy flows.
- The study of energy flows within ecosystems is based on the First and Second Laws of Thermodynamics
- Different forms of energy differ in their ability to do useful work. A calorie of dispersed heat cannot do any work and sunlight must first be concentrated to be able to do useful work.
- It takes energy to concentrate energy. Some energy must be degraded in order to concentrate what is left.
- High-grade energy is wasted if it used for purposes which can be provided by using low-grade energy.
- Exergy is available energy, the maximum fraction of an energy form which, in a reversible process, can be transformed into work.
- Exergy can also be applied to take into account the quality of minerals used to manufacture goods.
- There can be no production of goods and services without exergy destruction. Unlike energy, exergy is not subject to the law of conservation.
- Emergy is the total energy used or embodied in the life cycle of a product in terms of the available energy of one kind that has to be used directly and indirectly to make a product or service
- Different products and processes make use of different forms of energy, each of which give rise to different levels of CO2 contributions to the atmosphere. Use of Emergy alone is therefore inadequate for making true comparisons of the environmental impact of different products. The same applies for Exergy.
- The First Law Efficiency is the ratio of the amount of energy delivered to perform a task to the amount of energy that must be applied to achieve this task.
- The second law efficiency is a measure of how much the performance of a task falls short of what is theoretically possible, and can be used as a measure of the conservation of free, or available energy (exergy) in carrying out a task.
- The Maximum Power Principle proposes that natural systems tend to operate at an efficiency that produces a maximum power output.
- For each unit of fossil fuel energy extracted from the ground, there is an energy cost involved in doing so. Whether or not the extraction of fossil fuels from the ground results in net energy depends upon the energy cost of extraction.
- The energy return on energy invested (EROEI or ERoEI) or energy return on investment (EROI) is the ratio of the amount of usable energy (exergy) delivered from a particular energy source to the amount of exergy used to obtain that energy resource.
- The Energy Store on Energy Invested (ESORI) is used to analyse energy storage systems.
- Economists claim that price mechanisms takes energy and other resource factors into account and is a better tool than Energy Analysis for allocation and decision making. However, the pricing of fossil fuels over the past 40 years has not provided adequate signals of the need to transition from fossil fuels to renewable energy, and nor has it provided any indication of an impending peaking of all forms of fossil fuels.
- Economist claim that Energy Analysis gives no credit for capital and no allowance is made for improvements in technology. Economics alone cannot determine physical and thermodynamic limits to technology and access to resources. Both Economic Analysis and Energy Analysis are needed to guide a transition from fossil fuels to renewable energy and infrastructure and a sustainable future beyond.
- Ecology can be defined as that branch of science which studies the relationship of living organisms with each other within their physical environment
- Organisms and their physical environment form ecosystems. Human settlements also form ecosystems within larger ecosystems.
- A food chain is linear and follows the generalized form of Plant - Herbivore – Carnivore
- In nature, the food and feeding relationships of plants and animals are rarely in the form of a simple linear food chain, but instead interconnects with a large number of other food chains to form a food web.
- A food web can become extremely complex and tampering with a food web can have some unexpected and undesirable effects.
- Animals at the base of a food chain are relatively abundant, while those at the other end are relatively few in numbers.
- Humankind has been able to tap resources of energy which other parts of the ecosystem cannot use. By utilising this energy, humankind has been able to sustain a larger population than that of other similar sized animals.
- All ecosystems have developmental stages corresponding to that of a single organism - birth, early rapid growth, followed by maturity. Each developmental stage brings and ecosystem closer to steady state, a state of homeostasis in which there is a dynamic equilibrium interaction between the ecosystem and its physical environment.
- Succession is a natural process where organisms within the same ecosystem succeed one another by maximising their energy inflow until a highly stable climax ecosystem develops.
- A climax ecosystem is stable and in a condition of internal self-regulation where feed-back mechanisms enable the ecosystem to return to equilibrium following any stress of change in climate, energy, and nutrient resources.
- Humankind has been able to crop a high yield from an unstable agricultural ecosystem by feeding in energy in the form of fertilizers and insecticides.
- Monoculture systems of growing crops, building dams and roads, and pollution threaten the homeostasis of ecosystems.
- The carrying capacity of an environment is the maximum population of a species that can be supported in that environment.
- The carrying capacity of each organism in a given environment is limited by the stock of any indispensable necessity of life that is in shortest supply.
- The ultimate limiting factor of total biomass (combined carrying capacities of all organisms) in an ecosystem is the process of photosynthesis carried out by plants, algae, and certain bacteria.
- If humans wish to maximise food and energy resources, then humans should remain exclusively herbivores and feed directly off plants and use sustainable phytomass as fuel alongside with hydro-electricity and other solar based energy sources. In doing so, humankind would be sharing the available net phytomass alongside other herbivores.
- For humankind to attempt its own monoculture of species would be to upset the balance of nutrient and energy cycles resulting in succession of humankind by lower order species. Humankind needs to live in harmony with plants, animals, insects, birds, fish, and bacteria in order to survive.
- In striking a balance between food consumption and energy consumption from phytomass together with other forms of solar energy collection, we need to understand more fully the patterns of energy flows within ecosystems and, in particular, our own energy flows and their impact on the environment.