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Waste to fuel - Conversion of waste into energy

Organic solid waste is a biomass that can be exploited to produce green energy.
The Eni Research Centre for Non-Conventional Energy has studied and developed a technology that transforms such waste into bio-oil to be used for electricity generation and transport.
Eni plans to build a pilot plant in 2012 and will design and build a demonstrative plant in the following years, according to the first results.


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Solid waste of organic origin is a biomass that can be used for the production of renewable energy. Waste consists mainly of the wet organic fraction of municipal solid waste, pruning from gardens and parks, sewage sludge from urban wastewater treatment plants, waste from food processing and from large scale retailers.
The Research Centre for Non-Conventional Energy - Eni Donegani Institute has studied and developed a technology that transforms such waste into bio-oil with high calorific value for electricity generation and for the automotive field.

The main benefits are:

  • the use of raw material that already has a collection chain, offering an alternative solution for the management of municipal waste/sludge and protecting the environment;
  • the technology is not in competition with the agricultural production and offers a sustainable alternative to the management of waste products;
  • wet biomass is treated as such, without any expensive drying step;
  • the conditions used in the process are milder than in other thermo-chemical conversion processes.

Organic fraction of municipal waste (OFMW)Solid waste of organic origin is a biomass that can be used to produce renewable energy. It includes 4 main types of waste:

  • the wet organic fraction of municipal solid waste;
  • pruning and mowing from gardens and parks and agricultural waste;
  • the sludge produced by urban water treatment plants;
  • waste from food processing and retailers.

The main feature of organic solid waste is the high water content: sludge and organic fraction have a moisture content from 60 to 70%.

Sludge produced by urban water treatmentEach year Italy produces and collects more than 32 million tons of municipal waste; about 3.8 million tons are "organic" and collected separately. The percentage of the organic fraction of municipal waste (OFMW) is expected to raise gradually due to the increasing introduction of recycling.

Currently, most of such material is disposed of in landfills or, in the best cases, sent to anaerobic digestion plants (to produce biogas), composted (to produce fertilisers) or incinerated after drying (to produce energy). From Eni's point of view, organic waste can be transformed in renewable energy.


Bio-oilAs an alternative to landfill, such waste can be used as feedstock to produce bio-oil, that can be utilised directly as fuel or upgraded into bio-fuels for motor vehicles.
The thermo-chemical reaction which converts biomass into bio-oil is liquefaction, which is carried out heating the feedstock in presence of a liquid fraction, generally the water contained in the waste itself. The initial carbon content of the biomass is concentrated into the bio-oil.
Biofuels are fuels derived from biomass feedstock that can replace or supplement conventional fossil fuels, such as gasoline and diesel, in automotive, aviation and marine fields.
Gradual replacement of traditional fuels with biofuels is foreseen and encouraged by international commitments (Kyoto Protocol and European Community Directives) and Italian laws. So far , the EU aims at replacing 10% of fossil fuels with biofuels by 2020.



The Research Centre for Non-Conventional Energy - Eni Donegani Institute is currently conducting research to develop a technology for the production of renewable energy from waste.
A waste liquefaction process has been developed on lab scale. It is coupled with a stage of bio-oil refining (upgrading) and with cleaning of the produced water thanks to fermentation with micro-organisms.
Eni plans to build a pilot plant in 2012; according to the results, Eni will design and build a demonstrative plant in the following years.

In this process, waste is homogenised and fed to a liquefaction reactor for thermal treatment (250-310°C for 1-2 hours) to produce bio-oil with high carbon content (about 70-75% by weight). After purification, the bio-oil is used as fuel oil (to produce electricity) or upgraded into petrol and diesel for motor vehicles. These fuels are suitable for cars, both in terms of engine performance and CO2 emissions, which must comply with current regulations.

The water phase obtained by liquefaction contains a percentage of organic substances that are not easily processed by regular plants for water treatment. Therefore, this phase is used as media for fermentation with microorganisms. This step reduces the organic content, with consequent fewer problems downstream, and produces an additional amount of biomass, that can be recycled in liquefaction, increasing the overall yield in bio-oil.

The main benefits of the process under development are:

  • the use of a raw material that already has a collection chain, which offers an alternative solution for the management of municipal waste/sludge protecting the environment;
  • using waste, the technology is not in competition with agricultural production and offers a sustainable alternative to the management of waste products;
  • wet biomass is treated as such, without any expensive drying step;
  • the conditions used in the process are milder (250-310°C) than other thermochemical conversion processes, such as pyrolysis (400-500°C) or gasification (800-1000°C);.
  • the produced bio-oil has a high carbon content and high calorific value (about 35 MJ/kg versus about 40 MJ/kg of fossil oil);
  • a higher energy yield than the use of waste for biogas (approximately 70-80% versus 40% based on LHV – Lower Heating Value);
  • for complying with national obligations on renewable energy imposed on operators, this technology produces biofuels with a double value compared to the others.

In 2011 the Eni waste-to-fuel technology received the Eni Award and the National Award for Innovation "Prize of Prizes" given by the Italian President Giorgio Napolitano to the researchers from the Research Centre for Non-Conventional Energy - Istituto eni Donegani in Novara with the motivation: "for an innovative technological solution for energy recovery from organic waste, producing bio-oil to be used as fuel or to produce next generation biofuel."




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Last updated on 09/08/12