a result of their composition. Coal is basically wood and other organic 

 matter which, over periods of geologic time, has been compressed, heated, and 

 eventually carbonized and has a higher energy quality factor (Table 1). The 

 use of energy circuit modeling to diagram the flows of wood and coal into a 

 foundry process is illustrated in Figure 2. Note the geologic upgrading of 

 wood to coal in the model. The plants are diagrammed as a producer and the 

 foundry as a consumer unit. 



Table 1. Energy quality factors for various fuels (Odum and Odum 1976; Alex- 

 ander et al . 1980b.) 



Power Energy Quality Factor 



Source (solar cal /cal ) 



Sun 1 



Wood 1,000 



Coal 2,000 



Oil 3,400 



Gas 3,400 



Electric Power 8,000 



The wood, coal, and oil and gas factors represent estimates of the dif- 

 ferent quantities of solar energy required to produce these fuels and also 

 give an indication of how much of each will be required in a specific indus- 

 trial process. The higher the quality "factor of a given energy source, the 

 better able it is to do useful work. Consequently, the energy quality factor, 

 compared to solar energy, is the best indicator of the inherent worth of a 

 given energy type. Quality factors provide a way of estimating the value of 

 the natural energies and of comparing than to other types of energy such as 

 those associated with animals, human culture, materials, and information (Odum 

 and Odum 1976). Infomiation in this context refers to the flow of concentrat- 

 ed energy between a sender and receiver as in a radio broadcast or human 

 speech. The flow of information is an example of a very highly concentrated 

 energy flow, i.e., it takes large quantities of solar energy to power systems 

 which in turn produce information flows in a control action. 



ENERGY AND MONEY 



The interaction of energy and money of a farm is illustrated in Figure 3. 

 In this simplified energy circuit model of a farm, renewable natural energy 



309 



