US researchers say agricultural waste from coconut and mango farming could generate significant amounts of off-grid electricity for rural communities in South and South-East Asia.

Many food crops have a tough, inedible part which cannot be used to feed livestock or fertilise fields. Examples of this material — known as ‘endocarp’ — include coconut, almond and pistachio shells, and the stones of mangoes, olives, plums, apricots and cherries.