A t the beginning of the new millennium, energy insecurity, global climate change and stagnant rural economies led to policies supporting domestic biofuels as a renewable alternative fuel in more than 60 countries worldwide 1. As a consequence, global production of ethanol and biodiesel combined almost quadrupled (from about 35 billion litres to 135 billion litres) in the short span from 2005 to 2016 (ref. 2). However, these policies had two major flaws. First, appropriation of edible crops for biofuel (mainly corn and sugarcane for ethanol, and soybean, canola and palm for biodiesel) was an important factor responsible for food price inflation alongside other factors such as rising income that drove rapid growth in food demand (especially meat demand), rising energy prices, adverse weather shocks, currency fluctuations and trade policies 1,3-6 , the consequences of which were particularly severe for poorer households in developing countries 7. Second, these crops required intensive use of land, water, nitrogen and other farm chemicals, which meant low, and in the worst case uncertain, net environmental benefits 8-12. Being widely available and replenishable, wastes and biomass residues from agricultural, dairy, forestry and household activities seem to contain the basic attributes of a sustainable energy resource, in stark contrast to bioenergy from food crops 13-15. The US Department of Energy 2016 Billion-Ton Study estimates an annual availability of 233 million tonnes (Mt) of dry waste 16. To put this in perspective, the approximately 60 billion litres of corn ethanol produced in the United States in 2017 required about 150 Mt of corn (assuming a yield of 402 l ethanol per Mt). Furthermore, wastes and biomass residues can be used to derive a number of alternative energy products, including electricity along with heat, biomethane (or renewable natural gas), ethanol, renewable diesel or bio jet fuel, each through various conversion pathways, which currently are at different stages of technical and economic maturity 14,15,17-21. Beyond energy production and mitigation of climate change, efficient use of wastes and residues is integral to the achievement of sustainable development 22 , and to redesigning our economies to minimize