To reduce greenhouse gas emissions, countries need to transform their energy system by increasing the share of renewable energies. For years, the use of fossil fuels meant devoting little land area to energy provision. As renewables require much more space, the relationship between renewable energy and land area becomes highly relevant. In this context, land scarcity is an important challenge, especially for densely populated countries. The power density concept, describing the relationship between energy carrier and area used for its production in W/m², can aid decision-making for resources allocation. Bioenergy plays a key role in the energy transition due to its diverse applications. Here, we assess how much area it takes to generate, transport and process various biomass types for energy purposes. We differentiate between 10 biomass types, determining area requirement (m²) and energy input (kWh) for each process along the supply chain. Using the whole sustainable biomass available requires >0.1% of Switzerland's land area (31 km²). Particularly for waste biomass, the area required for energy is negligible. Power densities vary widely within and between biomass types. Taking the average between minimum and maximum, they are highest for coniferous protection forest against natural hazards 114 W/m² (22–267 W/m²) and green waste 96 W/m² (26-176 W/m²). All of these are lower than literature values for fossil fuels (>1000 W/m²). However, sustainable power densities including compensatory land for greenhouse gas emissions are higher for biomass (average 2.4 W/m², maximum 14.4 W/m²) than for fossil fuels (natural gas 0.9 W/m², coal 0.2 W/m²). Estimating land requirement and power density facilitates weighing up whether and to what degree different biomass types should be used for energy.