UK engineers call for green power from household waste

Report claims domestic rubbish could provide up to 20% of Britain's energy needs
Alok Jha, Green technology correspondent
guardian.co.uk, Thursday December 4 2008 17.18 GMT

The UK produces enough waste to fill the Albert Hall every two hours.
Household rubbish should be used to produce green power rather than being sent for recycling, according to energy experts.
At a briefing today to launch a new report by the Institution of Mechanical Engineers on dealing with waste, the authors said that converting waste could provide up to a fifth of the UK's electricity needs in future and help the country meet its renewable energy targets.
But environmentalists have voiced concerns over the report, insisting that recycling rubbish is still the better option in terms of tackling climate change.
The UK produces more than 300m tonnes of waste every year, enough to fill the Albert Hall every two hours. Most of this is buried in landfill, though new EU legislation will require a 50% cut in the practice by 2013.
"We can't afford to do that any more, we're running out of space for landfills," said Ian Arbon, a visiting professor in energy systems at Newcastle University and author of the new report.
"We see energy from waste as being one of the brightest hopes for reaching our 2020 target to source 15% of our energy requirements from renewables.
"We will not meet those targets without energy from waste."
Energy can be harnessed from waste in several ways, depending on the type. The two proven methods are combustion, where waste is burned to produce electricity and heat, and anaerobic digestion, a biological process where waste is treated to produce methane, which can then be used for fuel. The former is most suitable for dry waste while the latter is best for wet or organic waste.
There are fewer than 50 small-scale energy-from-waste plants operating in the UK at the moment, a combination of combustion plants and anaerobic digesters. This compares to several thousand in countries such as Denmark and Germany.
In the past, burning waste in incinerators has been opposed by local residents worried about air pollution. But Arbon said that, using modern combustion methods which scrub out harmful particles from the gases vented by the power plant, every community in the UK could have a waste-processing facility on its doorstep.
"Then you're handling the community's waste locally and you're not having to transport waste large distances, which gets people upset."
Gaynor Hartnell, deputy director of the Renewable Energy Association, added that converting all the country's household and commercial waste, around 75m tonnes per year, could provide significant benefits. "If it all went into electricity, you could get about 17% of the UK's electricity demand from waste [by 2020]."
But Matthew Warhurst, senior resource and waste campaigner at Friends of the Earth, warned that building a new fleet of energy-from-waste plants would miss climate goals. "Household waste is a mixture of fossil-derived plastics and textiles and biologically-derived material, [burning it] you end up producing a lot of carbon dioxide."
Another way of dealing with waste is to recycle it but Arbon urged caution on assuming this was the best option "In this country we have very few recycling plants.
"We do reasonably well with metals and we can handle some paper but, because we've lost most of our manufacturing might in the UK, we ship our waste to china - that process absorbs a lot of energy."
Recycling is an energy-intensive process, said Arbon, the opposite of producing energy from waste. "The energy that we use to recycle mainly comes from our existing energy-production systems, which are 90% fossil fuels.
"Let's get honest about recycling, about how well we do at that. For some things, it's the right thing to do, for others it isn't."
However, FoE's Warhurst said that stepping up recycling facilities was an urgent priority, as was avoiding putting things into landfill that could go on to produce methane, a potent greenhouse gas.
"Rather than building huge plants to burn waste inefficiently, it is better for the climate to be building plants that compost the remains, remove further recyclables and then even if you end up putting what's left in landfill that is a better climate option."