Energy does not equal Energy

Sustainable. Clean. Economical. High thermal efficiency… slogans used to market energy technology. But is there a way to seperate the chaff from the wheat? Do we have a criterion enabling us to tell with mathematical precision, how useful a certain technology is for humanity and how ecofriendly?

The lights of civilization on nocturnal earth.

The answer is: yes. It is the so-called EROI (Energy Returned on Investment), the ratio of delivered energy to that needed for running the technology — construction, maintenance, fuel acquisition, etc. The EROI is intimately tied to energy and power density. Concentrated energy sources (fossil burning, hydropower, nuclear) boast high EROIs, diffuse sources (wind, solar, biomass) lower ones. The higher the EROI, the more work the technology can take off the shoulders of mankind, and the fewer disturbances of nature are necessary.

When comparing the EROI of light-water nuclear power with that of coal plants, one may be puzzled: The former is merely twice as large as the latter — in spite of the calorific value of uranium surpassing that of coal by two millions! Obviously there is substantial room for improvement concerning nuclear power. This is where the DFR comes in: It uses fission fuels with maximum efficiency, enabling it to effectively compete with fossil fuels and grow up to become a central pillar of world primary energy supply.