The
power density of sustainable annual tree growth in temperate climates is at best
equal to 2 % of the
power density of energy consumption for traditional urban heating, cooking, and manufactures.
However, let's say that white noise has a «flat
power spectral
density,» which seems to mean that at any frequency the signal contains
equal power, much in the same way that a white light distributes
power over the visual frequencies in a way that stimulates our colour receptors equally.