A new method of processing food waste into fertilizer has been outlined in a recent study. The process uses a digester system with microorganisms to break down organic waste into fertilizer. The resultant fertilizer was used in a low-energy greenhouse to produce a range of food crops. The method is a potential way to utilize food waste and reduce the energy consumption of food production as part of a circular economy. The eco-innovation project Food to Waste to Food (F2W2F) aimed to develop an integrated system to recycle food and garden waste and reduce the energy costs of producing food in greenhouses for local use. This study outlines the way F2W2F used dig estate as part of greenhouse horticulture in a prototype system. The system uses a biogas plant which includes a digester — a container where substances are exposed to heat and microorganisms in order to aid anaerobic digestion — to process both food and garden waste into digestive. The resulting digestive is then further treated with earthworms and mixed with compost so that it is not toxic to plants. The researchers also used a new bubble-insulated greenhouse technology, which uses soap bubbles between double foil for thermal insulation of the walls and roof, and a climate-control system to reduce energy use. The soap bubbles are circulated in tanks, which form the greenhouse walls, and water pumped through these tanks can be heated or cooled to control the greenhouse temperature.

A commercial-scale bubble greenhouse is now operating in Poznan, Poland. The researchers say further research is needed to confirm the optimal growing conditions for different crops, as well as up scaling of the system to make it commercially viable to produce food crops for local sale and consumption. This is currently happening in Norway, where public innovation funds have financed a large commercial-scale pilot to be completed by the summer of 2017, in cooperation with commercial greenhouse growers.