Modern incinerators comply with the tightest regulatory emission standards and produce energy from waste, yet the way green activists depict them, you would think they were the fiery furnaces of the devil. Among possible alternative means for dealing with Britain’s residual waste, one technology that has suddenly received a huge boost is pyrolysis.
Pyrolysis emerges with a generally favourable assessment in the latest WRAP report, Environmental benefits ofrecycling – 2010 update. A finding which, by extension, also enhances the prospects of a closely related technology, gasification.
Pyrolysis appeared preferable over incineration regarding the impacts on climate change and depletion of abiotic resources. The analysis also suggested that pyrolysis is less energy-demanding than either recycling or incineration.
As industrial processes go, pyrolysis and gasification are not new. They’ve been kicking around since the19th century, including in the coal industry. Their adaptation for waste management purposes is a relatively new development. Like incineration, they are thermal processes but what distinguishes them is that no oxygen is used in pyrolysis and only low concentrations in gasification. Waste is ‘cooked’, not ignited. The result, the developers contend, is super-low pollution and electricity generation from far lower volumes of waste than is typically processed by incinerators. And pyrolysis/gasification plants, because modular, can be physically far smaller, so less obtrusive and ideal for handling locally produced unrecyclable waste in line with the ‘proximity principle’.
WRAP’s report, while upholding recycling as the preferred waste management option, confirms that pyrolysis does look highly promising. The report is based on analysis of more than 200 life cycle assessments of various waste stream materials worldwide. Although data for pyrolysis was only available for plastics, WRAP concludes: “Pyrolysis appeared preferable over incineration regarding the impacts on climate change and depletion of abiotic resources. The analysis also suggested that pyrolysis is less energy-demanding than either recycling or incineration. The performances regarding eutrophication and acidification also confirm that this is a promising option. This technology is still in early development and so the results may not be representative of commercial operations. Nevertheless, the results highlight that pyrolysis should be promoted, in line with the UK policy that aims at promoting energy from waste.”
Yorwaste’s plant at Seamer Carr near Scarborough is perhaps the most exciting UK project to have sprouted thus far. Utilising pyrolysis technology made by GEM to generate electricity and heat from domestic rubbish, the project has developed as part of the New Technology Demonstration Programme run by Defra, and is largely funded by Defra, private investors and regional development agency Yorkshire Forward.
There are several other technologies that consist of partial pyrolysis technologies but our plant is the only technology of its kind that has been demonstrated as a fully integrated continuous waste to energy process.
GEM business development director Huw Davies
“GEM, with Yorwaste, has the only true pyrolysis plant in the UK,” asserts GEM business development director Huw Davies. “There are several other technologies that consist of partial pyrolysis technologies but our plant is the only technology of its kind that has been demonstrated as a fully integrated continuous waste to energy process.”
GEM’s kit processes waste-derived fuel, pyrolysising the solid/liquid matter into synthetic gas. The gas is conditioned for use either to replace natural gas in an industrial environment or for conversion into electricity for the grid. “GEM has proved the suitability of its technology for the conversion of any hydrocarbon based materials into synthetic gas,” says Davies. “This means that where any of the recycling markets fail, GEM can react by increasing the number of GEM converter modules to cope with the added throughput. Having built a demonstration facility that represents full modular size, GEM has proved the commercial suitability of its process. GEM is currently upgrading its demonstration facility in Scarborough to a fully operational commercial site.”
To what extent, MRW asks him, is it projected that the plant will help Yorwaste meet Government-imposed targets for regional authorities? “The GEM process recovers energy from waste that would otherwise be sent to landfill. While doing this, the energy is produced in the form of renewable electricity. Landfill diversion and renewable power is therefore achieved and this will help Yorwaste to continue bidding for waste contracts. Yorwaste will, by using the GEM process, be well within the Government-imposed targets and in fact be well ahead of the game for many years to come.”
Though UK local authorities and waste contractors have flirted with pyrolysis/gasification for some years via pilot schemes, none till now has fully committed to it. What has held up its application in the UK, Davies says, is that it is new to the waste industry so taking a while to gain acceptance.
“With difficulties in obtaining planning consent for large incinerators, the pyrolysis process is now being considered more favorably by the big waste management companies. Worldwide applications exist from municipal and industrial waste sectors and GEM – and I am sure the other technology providers – is experiencing huge worldwide interest for the use of the process. The process has been held up by planners, Environment Agency and funders for several years to the non-existence of fully integrated plant operating data. The lack of confidence has led to massive delays.
“Now that GEM has achieved its goal in building a fully integrated facility, planners have become more relaxed, the EA have a better understanding and have become very helpful and the funders are beginning to show more support. The next one to two years will see a step change in the advancement of the pyrolysis solution.”
Friends of the Earth last year published a briefing document that acknowledged: “Pyrolysis and gasification of municipal waste has the potential to be more flexible than incineration because it can be more modular. They may have some advantages in terms of emissions.”
But FoE argued: “Most local authorities are still not maximising recycling and composting. While this is the case, using pyrolysis and gasification will undermine recycling and composting – which are far better ways of saving energy and resources. Pyrolysis and gasification rely on a feedstock rich in paper, kitchen and garden waste and plastics. Increasing re-use, recycling and composting will dramatically alter the level of these waste streams in residual waste, and may therefore compromise the ability of pyrolysis and gasification plants to operate profitably.”
FoE concluded: “Pyrolysis and gasification of municipal waste is not a 100% renewable energy technology, and analysis has shown that it can be better in climate terms to landfill stabilised waste than to burn it, even with the claimed efficiencies of these technologies. Friends of the Earth’s view is that investment should be focussed on 100% renewable energy technologies, for example anaerobic digestion, or wind and wave energy.”
Davies, however, says public and local media reaction to the Yorwaste/GEM project has mainly been positive. “Interest remains high and as the project expands the media show more supportive interest. I am sure that FoE will be more supportive of our technology once they see an increasing amount of operational data being provided.
“When appropriate, GEM will engage directly with FoE in order to demonstrate the flexible approach and the adaptability of the technology. GEM is not looking to the mass-burn market and is supportive of the proximity approach. GEM does not have an aggressive marketing approach and will work with FoE in order to be sympathetic and pragmatic in its approach to the waste and renewable power markets. It is impossible to provide 100% renewable technologies, one has to realistic and adaptable. This is GEM’s approach. AD, wind, wave etc will all have a role to play, as will GEM’s pyrolysis solution.”