The tax of energy return, this great unknown. The EROI ( TRE in spanish) is the amount of energy needed to produce...energy or a raw material.
If Oil Peak is depressing, wait until you meet EROI: the price of fossil fuels and metals not only will rise because they are becoming more scarce but because to produce a unit of energy or metal you need to remove and work out more tons of rocks. Only to find an ore or oil of lower quality.H ence, doble spiraling of prices. According to New York University, the minimum acceptable EROI is 3:1, but if we wish "luxuries" like Public Health System or Education, has to be higuer. For example, Biofuel barely reaches 3:1, and sometimes has to be subsidized with petrol. Photovoltaic energy is between 7:1 y el 10:1, by the way.
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Raw materials: To produce 1 MW of electricity you need 1 Ton of Copper. This means that if we need more energy, we need more fuel and more metals. Therefore growing is impossible due to the exhaustion of raw materials. We are then not only talking about Oil Peak: Gold peak,copper, zinc, uranium, silver and so on...
( Img: A Falling EROI: www.theoildrum.com)