Energy Density refers to the amount of energy that can be contained in a given unit of volume, area, or mass.
Power Density refers to the amount of power that can be harnessed in a given unit of volume, area, or mass.

Give an example of how renewable energies compare to hydrocarbons in terms of energy or power density.

Renewables require a much larger land area than hydrocarbons to produce comparable outputs, or batteries are extremely heavy compared to hydrocarbons.