Can EfW power up to be a renewable contender?

Energy-from-waste is well established as a treatment process, but how much potential does it have as a renewable energy source? Dean Stiles investigates

Energy-from-waste (EfW) is potentially a significant contributor to UK energy needs in terms of heat and electricity. Viewed in the context of the emerging low carbon energy sources it has a role not only as a waste treatment process, but also as a contributor to renewable energy generation.

The topic came under the spotlight at the recent Futuresource conference, held in London this June. Speaking on the issue, Professor Matthew Leach, vice president at the Energy Institute, said: "The exciting development is how the scale of EfW might come down from traditional large-scale incineration to smaller scale, decentralised thermal or biological processes, reducing transport distances, making easier use of heat production and changing the sort of interactions with local residents.

"EfW can in my view make a significant and worthwhile contribution to national energy needs, but it is not going to meet more than a small share of overall demands. But the same is true of a wide range of emerging and low carbon energy sources: wave, tidal stream, even biomass."

According to Professor Leach, the future energy mix is likely to consist of a much wider range of sources than at present as there are few options for low carbon energy that are conceivable at very large scale. Rising energy prices - oil and gas prices are not only high, but also extremely volatile - will improve the case for most of the emerging energy sources.

He believes that EfW is probably less at the mercy of energy prices than wind or wave generation as the revenues come from both energy sales and waste disposal fees, and the latter seem likely to remain high and rise. The financial benefits of EfW are a complex mixture of revenues from energy generation plus savings in landfill costs, but both elements are important. In addition, there are several, very different waste streams that can contribute.

These include: mixed municipal waste that after recovery of some material components might go to large incineration or smaller scale gasification/pyrolysis; putrescible or green wastes that would likely go to anaerobic digestion; and other waste streams like woody wastes that might be made into refuse-derived fuel or chips for smaller scale heating or CHP.

A political priority
EfW is part of the Government's strategy for waste and renewable energy generation and is top of the policy agenda. Dr Elizabeth McDonnell from the Department of Energy & Climate Change told delegates that EfW has a key role to play in maximising recovery of energy from unavoidable waste. In technology terms, the Government is encouraging landfill gas extraction, anaerobic digestion, incineration, biomass to liquid, gasification and pyrolysis.

These technologies are expected to provide 1% of renewable energy needs - the smallest contribution with wind power providing over 80%. Dr McDonnell said the Government expects £2.5B of further investment in large-scale CHP infrastructure in the UK because of government incentives for CHP that, subject to EU Commission approval, will be exempt from the Climate Change Levy until 2023.

EfW has the potential to provide a range of applications serving sub-regional or large urban markets. Professor Chris Coggins at Wamtech said that although local grids to link local and regional schemes are expensive to retrofit, they should be considered alongside any new large residential developments. He also believes there is potential for 'internalised' waste use by industry where reuse of waste could supply a proportion of its energy needs. For example, Professor Coggins believes that the European food industry could supply 20% of its energy consumption - electricity, heating, cooling - from its own waste.

Opposition still remains
However, none of these arguments are persuasive enough for environmental lobby groups that remain resolutely opposed to EfW. Michael Warhurst, senior waste & resources campaigner at Friends of the Earth puts the green case simply: "Don't treat residual waste as material to be burned or buried - view it as a resource."

He makes a financial case in favour of composting and separation of residual wastes. Contrasting the process with incineration, he argues it is cheap enough to be financed with five-year contracts, uses simple technology, and rarely meets with planning opposition. It is also flexible - adapting to changing waste volumes and composition, and able to provide feedstock for new technologies. Underlying his argument is the belief that incineration reduces the incentive to recycle and reuse despite several European countries with significant levels of EfW achieving high recycling rates.

But Professor Coggins points out that despite prevention, reuse and high recycling/composting rates, there will always be residual waste with wastes not targeted for separate collection, not segregated by households, contaminated wastes residues from collection and/or sorting. And that EfW is a valid use of wastes as an energy resource in this respect, meeting a variety of sustainability arguments.

He also believes that in terms of the climate change agenda, incineration is a much better option than landfill with a net minus carbon impact. "All waste management options cost money, and EfW should meet high efficiency standards through the generation of electricity and heat and cooling. Providing electricity and heating/cooling needs to be promoted as contributing to secure and diverse energy supplies with more stable prices."

Dean Stiles is a freelance journalist

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