The Waste to Fuel technology produces biofuels from the Organic Fraction of Municipal Solid Waste (OFMSW), made up of leftover kitchen waste. At Eni's Renewable Energy and Environmental R&D Centre in Novara it was designed, developed and patented the first of its type in the world. A continuous pilot plant was built at the end of 2018, at the Gela biorefinery, and assigned to Eni Rewind: it can process about 700 kg of OFMSW per day. The Waste to Fuel process produces 3% to 16% di bio-oil (depending on the composition of the original feedstock). This can be used directly as low sulphur fuel for shipping or refined to create high-performance biofuels. The process also creates gas (mainly biomethane and CO₂) and 60%-80% of water which, once purified, can be reused for irrigation or within production cycles. Other than waste, Waste to Fuel can treat sewage sludge, plant waste, waste from the agri-food industry and large-scale distribution.

Italy collects about 30 million tonnes of waste every year, of which 14 million tonnes is correctly separated. Of this, about 7 million tonnes is OFMSW. By promoting the increased and more accurate separation of kitchen waste, this figure could reach 10 million tonnes of OFMSW. Currently, it's mainly used to produce compost for agriculture and, to a lesser extent, biogas. An increasingly important sector, but with a rising cost for the community. By combining a well-managed separated waste collection and more Waste to Fuel plants across Italy, we could in theory obtain about a billion litres of bio-oil annually, equivalent to about 6 million barrels of crude oil per year. It would be like discovering a small oil deposit without having to drill a well, and, above all, without emitting any new CO₂. With a single operation, we could make a major contribution to Italy's energy security and, at the same time, reduce the quantity of waste and greenhouse gas emissions.

With Waste to Fuel, in two or three hours, we imitate the natural process by which nature took hundreds of millions of years to generate hydrocarbons from prehistoric organisms. At the core of this technology is hydrothermal liquefaction, a thermochemical process in aqueous solution that transforms the initial biomass into a sort of “biological petrol”, or bio-oil. At this stage, nearly all the energy contained in the initial organic material is recovered and concentrated, retaining the precious hydrogen-carbon component and separating out the water. Each step is studied to reduce losses and obtain a product with a high calorific value (35 MJ/Kg) and low sulphur content. The main advantage of hydrothermal liquefaction over other waste treatment processes is that the water doesn't have to be eliminated. Indeed, all other processes evaporate off the water by heating the biomass, with an obvious energy cost. In this case, however, the water is used in the reaction itself, harnessing its acidic properties at high temperatures. Furthermore, lower temperatures are used: 250-310°C rather than 400-500°C for pyrolysis and 800-1000°C for gasification. The energy yield is also good: 80% for hydrothermal liquefaction, compared to 50-60% for biogas and 10-30% for incineration. But Waste to Fuel's most persuasive advantage is the transformation of waste into bio-oil – waste that would have a disposal cost – thus making it a useful raw material as per circular economy principles.

Following the first pilot plant, designed for batch operation, realised at Eni's Renewable Energy and Environmental R&D Centre in Novara, the first continuous Waste to Fuel pilot plant was established at the bio-refinery in Gela, fed each day by the OFMSW collected by a waste management company in Ragusa. In March 2019 we signed an agreement with Cassa Depositi e Prestiti for the joint promotion of decarbonization projects and the fight against climate change. In March 2020, CircularIT was founded, the company is 49% owned by Eni Rewind, Eni's environmental company, and 51% by CDP Equity, a holding company of the Cassa Depositi e Prestiti Group, CDP. The company will develop industrial Waste to Fuel plants. During the course of the 2020-2023 Strategic Plan, Eni Rewind will launch projects for the construction of Industrial Scale Waste to Fuel plants, with an expected total processing capacity of 600,000 tonnes per year. In addition, in March 2019, Eni Rewind signed an agreement with Veritas, the Venice municipality for the management of environmental services. The aim is to construct an industrial Waste to Fuel plant on land reclaimed by Eni Rewind at the petrochemical site of Porto Marghera. This will transform up to 150 thousand tonnes of organic urban solid waste (OFMSW) into bio-oil and water each year.

Waste to fuel energy recovery is virtually carbon neutral, since, by using the bio-oil obtained to power heat engines, the same amount of carbon dioxide is generated that was present in the initial biomass, in turn captured from the atmosphere by plants and fixed in organic matter during photosynthesis. There is thus no need to add additional carbon derived from fossil fuels to this virtuous cycle. In other words, instead of being released into the atmosphere, the carbon is stored in the bio-oil and biofuel, so helping to reach the targets set by the EU's Renewable Energy Directive for transport (RED II). Solid residue, on the other hand, is made inert by recovering the remaining energy within the process itself, while the water is used in the production of biogas and biomethane and then purified for subsequent reuse in agriculture. In addition, if adopted in countries with economies where agriculture predominates, the system could provide an industrial outlet for the large amounts of waste biomass, and contribute to the supply of fuels for local markets.