United States – The combination of hydrothermal processing and anaerobic digestion is ‘more efficient and faster’ at turning food waste into energy, according to researchers at Cornell University in the USA.
They have shown that virtually all of the energy can be extracted from food waste by deploying hydrothermal liquefaction to produce a bio-oil that can be refined into biofuel. The remaining food waste is then subjected to anaerobic digestion to convert it into methane which can be used in the generation of electricity and heat.
‘If you used just anaerobic digestion, you would wait weeks to turn the food waste into energy,’ explains postdoctoral researcher Roy Posmanik. ‘The aqueous product from hydrothermal processing is much better for bugs in anaerobic digestion than using the raw biomass directly. We’re talking about minutes in hydrothermal liquefaction and a few days in an anaerobic digester.’
Food waste contains large amounts of carbon and should be regarded as a high-value resource, Posmanik insists. The United Nations’ Food and Agriculture Organization reckons around one-third of the world’s food is either lost or wasted.