Just like nature

 By Luca Longo

Take nature as an example and recreate its natural processes. This is the goal that Eni researchers have set themselves in these years and the result of this long journey lies in Gela, the future of energy runs through there…

In 2012, at the Eni Research Centre for Renewable Energy and the Environment in Novara, the first process transforming the organic fraction of solid urban waste into bio-oil began and has been named Waste to Fuel (W2F).
This year in Gela, the first continuous pilot plant based on this technology started up, realized by Syndial, Eni’s environmental company.

From urban waste, stems a hydrocarbon that can be used directly as a fuel or sent to a later refining phase to obtain biofuels for our cars.
Eliminating waste or – better still – finding ways to use it to extract the energy still contained in it, is a goal that so far, is being pursued in the whole world. But the first invention is “made in Italy” as well as its first complete industrial realization.
An invention that has very ancient roots is the latest highly technological evolution of a process as old as human beings: that of burning waste to eliminate it and to recover some of the energy that is still trapped in it.
Already in the Palaeolithic era, in fact, man had already realized that instead of just burning wood – he was able to burn the scraps produced by his family both to warm themselves and cook food.
From the caves to the metropolis, the process has always been the same. To obtain energy, it is necessary to consume other energy: urban waste, which by its nature is rich in water (it contains up to 70% of it), is heated until all the humidity is eliminated and the particles that make it up to pass to the gaseous state. In this way, they can finally burn and release their energy by heating caves, pile dwellings, houses, and skyscrapers.

A journey inside the pilot plant for waste treatment at the Novara Research Centre

Millions of years in a few hours

For a century and a half, we have learned that it is more effective and environmentally friendly to collect waste and burn it in large dedicated plants. From the first incinerators, built in Nottingham in 1874 and Manhattan in 1885, collecting waste from the city, concentrating it in one place and burning it all together offers advantages in terms of efficiency making combustion more controllable.
Eni researchers have thought of taking a big step forward by looking even further back to our Paleolithic friends and studying a greater and older natural event that occurs in several hundred million years.
This process, based on the anaerobic decomposition of the first living organisms, led to the creation and accumulation in the belly of the earth of the oil and natural gas we know so well. In this case, it took nature millions of years and enormous pressures that developed very high temperatures. But at Eni, they have learned to replicate the whole process in two or three hours at temperatures of just 250-310° C. And without even having to eliminate the water.

The first continuous pilot plant based on Waste to Fuel technology in Gela

The process is called thermo-liquefaction and makes it possible to transform the humid fraction of urban solid waste into the bio-oil (in other words, using the humid waste that often improperly call “organic” waste). The bio-oil produced can be used directly as fuel oil or it can be further refined in the new bio-refinery in Gela. This produces biofuels that can be used in our cars.
In other less technical and simplified terms, the main advantages of the process developed in Novara are many. First of all, waste, for which a collection chain already exists, is used as raw material, while at the same time offering an alternative and virtuous solution to urban waste/sludge management; this wet biomass is used as it is, i.e. avoiding drying costs typical of standard incinerators; it operates in blander conditions than other conversion processes such as gasification (800-1000°C) or pyrolysis (400-500°C). In addition, bio-oil is produced with high carbon content and a high calorific value (about 35 MJ/Kg) and with an energy yield of over 80%… significantly higher than the enhancement of biogas waste (50-60%) and incinerators (10-30%).

Gela's first Waste to Fuel oil

The new plant

After the first pilot plant, built in Novara and capable of handling half a ton of waste at a time, the construction of a much larger demonstration plant has recently been inaugurated and created by Syndial, who is managing it within the area of the Gela Refinery.

The plant – designed and built under the supervision of Eni researchers from Novara – is capable of handling 700 kg of organic waste per day supplied by the company for the regulation of the Ragusa’s waste management service. These are then transformed into 70 litres of bio-oil.
The plant is fully integrated and provides development of all the products, besides the bio-oil. Water is used for the production of biogas/biomethane and then purified so that it can be employed in agriculture. The solid part is instead transformed in an inert construction material by recovering its residual energy within the process itself. Finally, all energy recoveries are carbon neutral. That is, the carbon dioxide that is produced corresponds to the carbon present in the original biomass. So there isn’t any carbon net dioxide production within the entire process.
Research does not stop though: Novara and Gela are currently working on the optimization of the plant and on the intensive development of the entire process.
This revolutionary class of humid waste management facilities can make a decisive contribution for our country in its efforts to meet the goals set by the European Directive on Renewable Energy Resources (RES), while also allowing us to obtain advanced biofuel from waste materials… Recalling the joke used by our colleagues involved in this research that has become so popular: “just like nature does it, only faster!”

SEE MORE: Road to bioplastic by Michelle Leslie

about the author
Luca Longo