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Equation 6 · Part 11 · Power Density and What It Permits

subscript

Pd=EA t=CA×f=Cd fP_d = \frac{E}{A\,t} = \frac{C}{A} \times f = C_d\,f
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

The second confusion is with capacity factor . Power density is an area-normalised output rate; capacity factor is a time-normalised one. They multiply rather than substitute. Writing energy generated as E over a period t across area A , with nameplate capacity C and capacity factor f : Pd=EA t=CA×f=Cd fP_d = \frac{E}{A\,t} = \frac{C}{A} \times f = C_d\,f. The first factor, capacity density CdC_d , 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…

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.