By Andy May
Key question: Can renewables ever replace fossil fuels and nuclear?
Understanding the value of renewables, vis-à-vis fossil fuels and nuclear power, requires that we consider that all energy is not equal in value. In fact, the quantity we call energy can be misleading and many experts prefer the quantity called “exergy,” which is defined in economics as (source Exergy Economics):
“The maximum useful work which can be extracted from a system as it reversibly comes into equilibrium with its environment.”
Or it can be thought of as the measure of potential work embodied in a material or device. As Ayres, et al. (1998) argue exergy is a more natural choice as a measure of resource quantity than either mass or energy. Even today it seems BTU’s, a measure of heat of combustion, or MToe, million tonnes of oil equivalent, are commonly used and mislabeled energy…
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