EROEI of electricity generation
by Jamie Bull
See also The EROEI of energy balancing.
I've been spending a lot of time thinking about EROEI (energy return on energy investment) lately since Tim Helweg-Larsen atPIRC asked me for help with a report. The report, "The Offshore Valuation" was produced by the Offshore Valuation Group chaired by PIRC and it looks at the value to the UK of the offshore renewable energy resource.
Tim, ever present with the big ideas, asked me to have a look at the EROEI of a whole range of energy technologies. What I did was begin a trawl of the literature hunting high and low for figures on EROEI, EROI, life cycle energy, net energy, life cycle analysis, energy payback time, etc and the result was a table on page 61 of the report listing the average EROEIs I found.
The abstract for the study we delivered is below.
"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.
"In addition this study has found a suggestion of increasing EROEI for wind turbines and nuclear power, and a falling EROEI for coal, gas and solar power. Of these, the most significant is the reduction in EROEI of coal. The study examines the reasons for these relationships with the greatest reductions expected to come from carbon capture and storage and the greatest increases expected from increased size of wind turbines and lower energy inputs to nuclear fuel enrichment.
"Finally the study looks at the relative lifecycle efficiencies of grid connection and a number of other balancing methods. Grid connection and HVDC interconnectors are found to have a similar lifecycle efficiency of around 95%. Energy storage technologies have lifecycle efficiencies in the range of 45% to 75%."
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