“Energy Return on Energy Investment (EROEI) is calculated as the ratio between energy inputs and energy outputs for an energy generating technology. A process that uses more energy than it produces is by definition unsustainable in the long term. Technologies which require fuel generally have a lower EROEI than those which can extract “free” energy from the environment (wind, waves, tides, sunlight). As part of this study we have a carried out a review of published EROEIs and have found a high EROEI for marine technologies, lower EROEIs for solar and nuclear power, and still lower for coal and gas.
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