The potential of CAM crops as a globally significant bioenergy resource: moving from ‘fuel or food’ to ‘fuel and more food’

4–15% of the 2.5 bn ha of semi-arid land globally could generate 59 PW h year −1 of electricity without reducing food production, enough to make a major difference to global GHG emissions. The key is anaerobic digestion of a class of understudied, under-developed and hyper-water-efficient plants that use the crassulacean acid metabolism.