Equation 7 · Power Density and What It Permits
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the capacity density. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.
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subscript
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The first factor, capacity density , is a siting and engineering question; the second is a resource and dispatch question. Miller and Keith’s US measurements make the separation visible: they report 2016 mean capacity factors of 32.9 per cent for wind and 22.1 per cent for solar, with 90th-percentile values of 43 and 27.5 per cent, alongside power densities that are not in the same ratio at all [ 4 ] . A technology can improve its capacity factor for years without moving its power density, and the reverse. Van Zalk and Behrens found solar the only one of nine energy types with a statistically significant trend in power density over time, rising an estimated 0.42 watts per square metre…
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The first factor, capacity density , is a siting and engineering question; the second is a resource and dispatch question. Miller and Keith’s US measurements make the separation visible: they report 2016 mean capacity factors of 32.9 per cent for wind and 22.1 per cent for solar, with 90th-percentile values of 43 and 27.5 per cent, alongside power densities that are not in the same ratio at all [ 4 ] . A technology can improve its capacity factor for years without moving its power density, and the reverse. Van Zalk and Behrens found solar the only one of nine energy types with a statistically significant trend in power density over time, rising an estimated 0.42 watts per square metre per year; wind’s 0.17 per year did not reach significance [ 3 ] .
Sources cited in the surrounding passage
- [4] Observation-based solar and wind power capacity factors and power densities ↗
- [3] The spatial extent of renewable and non-renewable power generation: A review and meta-analysis of power densities and their application in the U.S. ↗
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