Oil from waste

A processing facility that can turn organic waste into valuable oil without creating hazardous emissions is to be built near Parma, Italy, within the next year.

The process mimics the geothermal processes that have created fossil fuels from buried organic matter subjected to extreme heat and pressure under the Earth’s surface over millions of years. It could help countries to become less dependent on imported fuel from volatile regions.

Once up and running the facility will be able to replace incinerators and landfills while producing a high-quality light oil at a cost of around $12 (£7.5) per barrel, said Dr Terry Adams, chief technical officer of plant designers Changing World Technologies (CWT). The light oil produced can be easily distilled intogasolene and kerosene.

This month a £12.5m prototype facility for ConAgra Foods’ Butterball Turkey plant is scheduled to go online in Carthage, Missouri. It is designed to process 200 tonnes of turkey offal daily and, according to CWT’s calculations, the waste will be converted into 78 tonnes of oil and 12 tonnes of gas, together with 10 tonnes of carbon and minerals and 100 tonnes of water.

The system can also process tyres, plastics, sewage sludge, paper and animal and agricultural refuse into useful substances. ‘The facility in Italy will be nearly a duplicate of our plant in Carthage, Missouri. It will process about 100 dry tonnes per day,’ said Adams.

CWT’s thermal depolymerisation process (TDP) uses pipes and temperature and pressure control to break down long chains of organic polymers before reforming them into new combinations to produce solid, liquid and gaseous fuels and chemicals.

The materials are pulped and water is added before the mix is heated and pressurised then brought to a lower pressure at speed, driving out the majority of the water and allowing minerals to settle out. The slurry is then heated, breaking the molecular chains. Distillation pipes separate the light and heavy oils from gas, water and powdered carbon.

Offal processing can also be altered to produce chemicals such as fatty acids for soaps, lubricants and paints. PVC processed in the unit will yield hydrochloric acid rather than the toxic dioxins produced when it is burned in a normal incinerator.

The process is 85 per cent efficient, generates its own energy and uses recycled water throughout. Steam created during processing is used to heat incoming material to recapture expended energy.

‘If the thermal process were applied to all agricultural waste in the US the oil produced would nearly offset all imported oil,’ said Adams. ‘The thermal process also produces a fuel-gas and a carbon product. The fuel-gas is mostly consumed in the operation of the thermal process, but some feedstocks would yield a substantial surplus, and this fuel-gas has about 70 per cent of the heating value of natural gas.’

The carbon produced can be used as a clean solid fuel or as an adsorbent material to remove pollutants such as lead and mercury from water supplies. Minerals from the waste can be added to soil to improve its water and nutrient-holding capacity.

Conversion of biomass materials into oil was investigated in the 1960s and 1970s by the US Bureau of Mines, but the quality of the fuel produced was inferior and the cost too great. Improvements on the process made by CWT in the 1990s made the process commercially viable.