There has been a growing interest in the use of bioenergy with carbon capture and storage (BECCS) to achieve a net reduction in greenhouse gases. BECCS involves the combustion of biomass to generate energy, using trees and grasses grown on both agricultural land and marginal land unsuitable for food crops. The resulting CO₂ emissions are captured, compressed, and transported to suitable underground storage sites. BECCS is an example of a Negative Emission Technology (NET), with others including the direct capture of CO­₂ from the air, afforestation and carbon capture by trees, and pulverization of rocks to enhance the natural weathering process and CO₂ uptake. These are controversial technologies because they are largely untested at scale and because we have limited understanding of their wider impacts on society and the environment.