Is emergy a legitimate scientific concept?

Emergy(for those with eye problems, note the "M") is a concept used in ecological design and eco-engineering.



According to Wikipedia:

Quote:

Emergy is the available energy (exergy) of one kind that is used up in transformations directly and indirectly to make a product or service.[1] Emergy accounts for, and in effect, measures quality differences between forms of energy. Emergy is an expression of all the energy used in the work processes that generate a product or service in units of one type of energy. The unit of emergy is the emjoule, a unit referring to the available energy of one kind consumed in transformations. Emergy accounts for different forms of energy and resources (e.g. sunlight, water, fossil fuels, minerals, etc.)

There is some controversy surrounding this idea, and some may even question its usefulness or validity. The legitimacy of eco-design and engineering doesn't necessarily depend on the legitimacy of the emergy concept, since good eco-design is largely based on good science and engineering practices. Ideally anyway, since some people may try to mix in pseudo-science with eco-design. Still, I am not sure about this emergy concept and struggle at times to understand it. How legitimate is it?

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