There is a substantial opportunity in converting otherwise unrecyclable plastic into something usable, and plastic can be converted into a hydrocarbon by a number of different methods. That hydrocarbon then has potential as a fuel in a burner or in a combustion engine dependent on composition.
However, while there are several examples of active development in this area it has so far not become an established part of waste processing, and there are a number of factors affecting this.
Process – there are a number of demonstrated processes that convert plastic into a hydrocarbon and which have been implemented by plants, many of which can show a net energy yield. The sensitivities to feedstock composition and contaminants are reasonably well understood with different processes and feedstocks producing different types of hydrocarbon output, and some opportunity existing in the processes to tune the output.
Commercial – any plant ultimately needs to be commercially sustainable, and while various models are proposed there are a range of further considerations that are determining how far down the path to implementation we have so far travelled.
Legislation – current and prospective future legislation significantly affects outlook for production of fuel from waste on several counts including incentives/taxation, and it is a changing and somewhat uncertain landscape which considering the longer timescales required to develop and roll out the entire waste-to-fuel infrastructure makes wide scale commitment challenging.
Feedstock – the evaluation of different sources and grades of feedstock is ongoing and a definitive path remains uncertain, especially considering longer term outlook and availability. This then affects the type of process required and output produced, logistics and commercial considerations.
End-of-waste – this step in the value chain is reasonably well understood and is being actively managed today.
Path to market – the final end use as fuel for the potential process outputs is not yet clearly defined, and the path the process the output takes through the fuel processing and supply chain is also under evaluation.
Fuel classification – certifying process output as a fuel or fuel component is under development.
Scale and logistics – different scale production models are under evaluation and which of these succeeds will be dependent on factors including those above.
Simon Brewster is director of industrial engines at Ricardo
Commercial attempts to use pyrolysis to make oil from plastic
Ricardo is currently involved in evaluating Plaxx, an oil produced from waste plastic by UK firm Recycling Technologies.
A number of other companies have tested the potential commercial opportunities of treating plastic this way.
Cynar plc: This company was established in 2004 and developed a method pyrolysis to turn end-of-life plastics into low-sulphur liquid transport fuel.
The company developed its technology with chemists at Loughborough University. Cynar plants were designed to convert 20 tonnes of waste plastic into 19,500 litres of fuel per day.
The company set about building facilities through partnership deals in the UK (see below), Ireland and Spain, but in January this year the company went into liquidation.
Suez: In 2010, Suez signed a deal with Cynar to set up 10 plants across the UK to turn end-of-life plastic into diesel.
Cynar exited from the deal and construction started on just one plant in Avonmouth in late 2011. The Avonmouth facility is planned to be able to convert 6,000 tonnes of non-bottle plastics, such as yoghurt pots and meat trays, into 4.2 million litres of diesel per year.
Commercial operations were scheduled to start in early 2015, but in June that year Suez reported that although the plant was producing diesel to the required specification, its launch had been delayed.
More than a year later and there is no indication when the Avonmouth facility will be up and running.
Enval ltd: This Cambridgeshire-based firm specialises in microwave-induced pyrolysis to break down aluminium and plastic laminate packaging.
As pyrolysis involves heating in the absence of oxygen, it is possible to separate the metal and then turn the plastic into gas and liquid fuel.
After gaining enough funds from investors, including from “major multinational brands”, the company launched a commercial demonstration plant in Huntingdon. It says a typical plant would be able to deal with 2,000 tonnes per year.
Pyrocrat Systems: An Indian company set up in 2011 that uses pyrolysis to process plastics and tyres into diesel, Pyrocrat says its method of pyrolysis can achieve a yield of 95%.
It boasts “raw material flexibility” in the feedstock, with facilities able to deal with plastic bags, bottles, mixed plastic scrap and laminates.
Plastic Advanced Recycling Corporation: A US firm based in Illinois formed in 1996 as a research and development company specialising in pyrolysis technology that converts waste plastics and tyres to fuel oil.
Its basic plastics-to-oil facility can process up to 10,000 tonnes of waste annually, but this can be increased by adding further units. Up to 60% of the processed waste is turned into mixed fuel, depending on the feedstock.
The firm has three operational plants in China.
Plastic2Oil: This US company developed a laboratory unit to test its conversion technology in 2009. It then proceeded with a number of test facilities that produce liquid fuel oil without the need for further refinement.
But in 2013 it was forced to cease operations at a Canadian facility in order to save money. Earlier this year chief executive Richard Heddle announced that this and other facilities would proceed
The machine at its Niagara Falls, New York, facility can deal with nearly two tonnes of plastic waste an hour.
List compiled by MRW