We are now at a turning point for fossil fuels, and decisions will need to be made about the best policies from here forward. The environmental goods, commodities, and services of economic systems can be evaluated in terms of real wealth, and these evaluations can be used to make decisions towards best policies in resource, economic and environmental management.
“Although there is energy in everything including information, we recognize that energies of different kinds are not equal, but can be compared by expressing everything in units of one kind of energy required [Emergy]. In this way, human services are found to require thousands of times more energy of ordinary kinds than do agricultural processes. The Emergy production and use per unit of time is called Empower. . . . The Emergy of one kind of energy required to generate a product or service of another kind of energy is the Transformity. The more energy transformation steps there are, the higher the Transformity. In an agrarian landscape, the resources of agriculture and nature are converged to support small cities. . . . [In fossil fuel based cities] the city processes reach out to surrounding zones in their interactions (Odum, Brown et al., 1995, pp. 5-6).
Maximum Empower Principle: At all scales, systems prevail through system organization that first, develops the most useful work with inflowing emergy by reinforcing productive processes and overcoming limitations, and second by increasing the efficiency of useful work (Odum, 2001, p. 3)
While power is derived from energy flow, empower is derived from the flow of emergy. The spectrum of these relationships can be viewed by plotting energy and emergy use within systems as a function of transformity (Tilley and Brown, 2001). Some of the issues that we might address with Emergy Synthesis include:
- Evaluation of environmental contributions of natural capital such as fish stocks and wildlife
- Evaluation of net emergy benefits and net empower yield of renewable energy technologies
- Evaluation of urban and rural carrying capacity
- Evaluation of development alternatives
- Diminishing returns of energy subsidies to agriculture and other high-tech economic endeavors
- Relative empower signatures (Odum, 2001, 2007)
For example, Odum calculates a very rough global carrying capacity.
Divide the global emergy budget by the emergy/person of the standard of living you wish to sustain. The global annual emergy budget per person ranges from about 1.0 E15 sej/person/yr in India to 40+ E15 sej/person/yr in developed countries. The Ambio article shows that the carrying capacity for people now is 3.2 times higher than it would be without fossil fuels and virgin mineral mining (Odum, 2000).
Net Empower Solar Photovoltaic Yield
Paoli, C., Vassallo, P., & Fabiano, M. (2008.) Solar power: An approach to transformity evaluation. Ecological Engineering, 34, 191–206.
Paoli et al. (2008) evaluated a small solar photovoltaic (PV) plant in Italy that used monocrystalline silicon (BP Solar BP585F) PV panels that covered 136 m2 (~1500 ft2), faced south at 30 degree inclination, and had max power output of 18,300 watts at 8% efficiency. This would be equivalent to a few home roof tops. The energy return on energy invested (i.e. Emergy Yield Ratio) was 1.03, meaning that 3% more energy was yielded than diverted from the economy for investment. Thus, zero return is surely within the margin of error and shows that PV is not a primary source of energy. In addition, they estimated that 28% of the total energy required to produce electricity with PV came from electricity. Another 23% was need to make the inverters and another 20% for maintenance costs.
HT Odum argued from a emergy-based viewpoint that making the leap from visible radiation of solar power with its solar transformity of one sej/J to electricity with a mean solar transformity of 250,000 sej/J, meant that PV was making too giant of a leap across the energy hierarchy. From a practical perspective that leap means that PV has to be a very inefficient means of making electricity.
On a side note I once estimated that the weather system used about 1,000,000 solar joules to make 1 joule of lightning. Nature is typically not efficient. The planet’s weather system works on about a 9% efficiency at transferring solar power into weather (winds, sea currents, etc). Photosynthesis is ~1% efficient. However, nature is great at doing a lot things at one time; for example, biodiversity is huge even though it is powered by 1% efficient machinery. That is another thing that the industrial/fossil age has biased us about. High efficiency is an aberration (Comment by Dave Tilley).