According to estimates by Water Footprint Network, for each ton of vegetables an average 300 cubic metres of water (300,000 litres) are needed; 1,000 for fruit; 1,600 for cereals; 4,000 for pulses. It is even worse for derivatives: 1,000 litres of bioethanol made from corn need 2.9 million litres of water; a ton of butter needs 5.5 million litres; a ton of beef steaks needs 15.5 million litres. Then there is war for land, or land grabbing, which according to Oxfam has doubled since 2008. According to FAO, at least 55% of all arable land is used for agriculture and livestock.  In this context of global scarcity of biomass and its factors of production, it is necessary to answer the question posed in the above mentioned article: are agricultural residues and the enormous...