War on waste

New European laws create a pressing need for the UK to review its waste management infatsructure. 

The Incineration of waste to generate power is set to become more commonplace in the UK as local authorities struggle to meet commitments of the Landfill Directive to divert waste from landfill disposal, thereby avoiding hefty fines. The incentive for local authorities is the steadily rising tax on landfill use, which went up by a third to £32 per tonne last April.

The growth of incineration will be met mainly using traditional mass-burn technology rather than new technologies that meet renewable energy requirements. At present burning waste makes only a small contribution to the UK's energy needs, but the proportion of municipal waste tonnage incinerated is rising steadily at the same time as total municipal waste is rising by about 1.5 per cent annually. Some of this waste is, importantly, classed as renewable.

The UK has historically been heavily reliant on landfill; in 2001, of the 28.2 million tonnes of municipal waste produced, 79 per cent was landfilled, 12 per cent recycled and 8 per cent incinerated with energy recovery through 15 or so plants. There are now 22 facilities, including plant due to come on stream later this year, handling a little under five million tonnes of waste. Additional plants in the planning stage or under construction could add another two million tonnes of capacity, increasing the national grid contribution of electricity generated from waste incineration from a meagre 291MW to 450MW by 2010.

Drax Power Station

To put this in context, the Drax Power Station, the UK's largest coal-fired power station supplying about 7 per cent of UK electricity needs, has 3,960MW output capacity so energy-from-waste is still small in overall UK energy terms but it is significant in terms of renewable energy generation. If energy from landfill gas is included, energy from waste contributed about a third of UK renewable energy production in 2006.

This is likely to double according to Sita, the UK's second largest energy-from-waste producer with four plants producing 67MW and the operator of the UK's oldest and largest energy recovery facility at Edmonton in London that opened in 1971.

Sita's energy-from-waste capacity is set to expand with planning applications made for facilities at Capel and Trumps Farm in Surrey that will handle 270,000t, a site in Cornwall for 240,000t, a third line at its Tees Valley facility that will add 125,000t, and a new facility in Telford for 62,000t. Sita also has planning permission for a facility in Binn Farm, Scotland for 60,000t, due to start operation in 2011.

Viridor has an 11MW combined heat and power facility in Marsh Barton, Exeter, due on stream in 2010, and, with Grundon, is to operate a 32MW plant near Heathrow due to start this year. WRG has planning consent for an 18MW plant at Salt End in Hull and is appealing planning refusal to expand its existing site in Nottingham. Cory expects its London, Belvedere site, which will produce 66MW, to be operating by 2010. And in the same year Veolia, the UK's largest energy from waste producer, expects its 16.5MW site in Newhaven, East Sussex to go live.

Energy from waste

Energy from waste plants is more about waste capacity than power generation, hence the reason for plant capacity being quoted in tonnes. An 80,000t plant will produce between 6MW and 9MW depending on the calorific value of the waste fuel. Growth in energy-from-waste generation is underpinned by the rising cost of waste disposal, principally because of the landfill tax, according to Mike Snell, general manager external relations at WRG.

"Energy-from-waste is a waste management issue and that's the way to look at these plants; they are not power stations. They are there to manage our waste more sustainable; to treat our waste safely and effectively, and the benefit of a modern waste facility is that you get energy or electricity. That's the way to look at it," Snell says. "Having said that, in places like Denmark they really have built their facilities into the city infrastructure. In a way, because these plants are so efficient at providing district heating, they almost do look at them as a way of generating electricity or heat."

The prominence of climate change issues has done much to improve the image of incineration in the UK, and the waste industry has been quick to promulgate the view that burning waste to generate power is beneficial because it reduces the amount of waste going to landfill and displaces emissions that would result from burning fossil fuel.

"Energy-from-waste along with ambitious recycling recovery targets is the way to go for the UK. That's been the experience of other countries in rest of Europe. Germany and Scandinavia have all got high recycling performances but they have also got strong elements of energy-from-waste; ergo, very little landfill," Snell says.

The government has supported this argument to a limited extent, arguing that recovering energy from waste material that cannot sensibly be reused or recycled is an essential component of a well-balanced energy policy, and one that most European countries already pursue vigorously. Europe's leaders in energy-from-waste processes, like Denmark, which disposes 68 per cent of its municipal waste in energy-from-waste facilities against the UK's 9 per cent, derives 3.6 per cent of its electricity supply from municipal waste.

The UK government supports emerging technologies for renewable power generation by offering them renewable obligation certificates (ROCs). But these favour conversion technologies other than incineration, such as anaerobic digestion, gasification and pyrolysis plants. Anaerobic digestion offers the potential to generate renewable energy - not only electricity but also heat and fuel - from manures and slurries and certain organic wastes such as food waste, while at the same time mitigating methane emissions from agriculture and landfill. These processes are attractive given the far larger waste tonnages available from agriculture compared with municipal waste and the high proportion of food waste in the municipal waste stream.

The efficiency of energy-from-waste plants improves considerably if they provide combined heat and power (CHP) but the UK has a very poorly developed infrastructure to adopt these systems, said Snell. WRG's Nottingham plant is one of a handful of plants producing heat, some 20MW thermal output in the form of steam for district heating schemes. Veolia's Sheffield plant, part of an integrated waste strategy for the city, handles 225,000t per annum to produce up to 61MW for the district energy network and up to 19MW of electricity to the national grid. Sita is looking at a scheme at its Kirklees plant to locally supply heat. These combined heat and power plants qualify for ROCs which "are an incentive for the development of CHP projects. However, EfW without CHP is also economically viable," says a Sita spokesperson.

CHP incineration

A stronger environmental case can be made for incineration using small-scale, CHP plants. Energos, part of UK sustainable power company Ener-g, has developed a gasification process, used in Norway and Germany, and is building a similar plant in Irvine, Scotland, that meets the criteria for ROCs. The technology is viable although slightly more expensive without ROCs. "We strongly believe that small-scale CHP is most effective as it is possible to make use of the heat, and the plant size limits the delivery of waste, making it a local, community-sized solution for local waste - not a regional solution," a spokesperson for Energos says.

"Wherever we have neighbouring end-users for the heat, we try to use CHP. Four of the Norwegian plants supply steam only, as does the German plant. At a proposed facility for Knowsley, Merseyside, we expect to offer steam to two adjacent chemical plants as well as creating electricity for around 10,000 homes," she says.

"We believe that our small-scale facilities, designed to handle local, residual waste, can operate harmoniously at the centre of a community where they complement recycling initiatives. This is proven at our existing operations in Norway and Germany, which have a proven track record of extremely low emissions," she says. "In site selection we look for energy consumers so that we can provide a CHP solution, and good road access avoiding residential areas. By finding suitable sites we minimise public antipathy from the outset, but we believe in being totally open with local communities from the start, providing full information on our advanced technology, so that they can make informed decisions. Where there is interest, we also set up community liaison groups," the Energos spokesperson says.

An increasing number of local authorities are adopting incineration for residual waste disposal and generating electricity as a by-product. And they are doing so with little government encouragement and despite the unpopularity of mass-burn with vocal sections of the public and environmental groups. Well researched reports, like that by Dr Hogg at Eunomia for Friends of the Earth in 2006, highlight that, in terms of green house gas emissions, energy-from-waste plants that generate only electricity, as most UK plants do, perform more or less on a par with oil-fired and coal-fired generation, with gas-fired generation performing far better. 

But incineration is a tried and tested technology that appeals to investors and to local authorities unwilling to gamble on new processes. The attraction for waste management is that energy-from-waste plants reduce the volume and weight of the waste by around 90 per cent and 75 per cent respectively. The resulting ash can be utilised in construction recycling applications. The residues from the air pollution control systems require further treatment or disposal in a landfill site. Large energy-from-waste plant also offers economy of scale. While the operating costs for mechanical and biological treatment (MBT) plants are similar to those for small incinerators at around £79 per tonne of refuse handled, costs for large capacity incinerators over 200,000t capacity drop to £37.8 per tonne, well below the £63.3 per tonne cost of similar sized MBT plants, according to the government's Waste Strategy for England report. "In terms of the future for energy-from-waste, it's matching up to local authorities' real need to get rid of residual waste. They are doing a lot to capture recyclable materials but the residual is the real conundrum," says Snell.

Planning applications for energy from waste plants are succeeding and capacity is greatly expanding. The same cannot be said for wind power generation, the panacea for renewable power generation. Shell is to sell its 33 per cent stake in the £2bn London Array wind farm off the coast of Kent and its partner in the development, E.ON, has indicated the project is under threat. And many other wind farm schemes are stalled in the planning stages, some for more than five years, a factor in Shell's decision to pullout. Given the problems that wind farms face, the less than glamorous route of generating power from burning waste has much to offer. 

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