Gasification: Why we should be fired up
Gasification not only helps with LATS targets, it can also offer a long-term, secure, discounted energy supply - so it's time local authorities took note, argues Nick Dawber
Although the concept is widely understood, it is little known that there is a commercially proven gasification technology available right now. It has been operating in Norway and Germany for more than six years, and is now set for operation in the UK.
The construction of the first full-scale UK gasification plant is due to open on the Isle of Wight this year. The plant, which is built by Energos, is part of Defra's new technology demonstrator programme, and will generate 2.3MW of electricity
- sufficient to power more than 3,000 homes.
The plant will generate electricity from the 30,000 tonnes of residual waste from the 60,000 tonnes currently being processed at the Island Waste Services resource recovery facility. This will demonstrate the capability of the technology to divert post-recycling refuse from landfill, therefore extending the life of the landfill site and helping the Isle of Wight Council to meet its LATS targets.
Another Energos plant, at Forus (Stavanger) in Norway, is a powerful illustration of how gasification technology can play a pivotal role in a local waste management strategy, enabling the LA to meet its obligations under the landfill directive.
In the Stavanger region, kerbside collections of paper, card, garden and kitchen waste, together with recycling at bring sites, enabled the area to achieve 56% recycling in 2006. Of the regional MSW, 32% was delivered as residual waste and treated at the plant. In addition to residual MSW, the plant received some commercial waste, taking 18% of its capacity.
From a total dependence on landfill, only 10% of the MSW collected in 2006 was sent to landfill. The 40,000tpa plant has been providing an important community function since 2002. The recovered energy provides electricity into the local grid and hot water into a district heating system for an adjacent industrial and commercial estate.
Meanwhile, over in Averøy in the Nordmore region of Norway, an Energos 30,000tpa plant serves a population of just 66,000. In 2004, the region produced 32,000 tonnes of MSW of which 26% was recycled and 19% was sent to landfill.
Of the MSW collected, 50% was residual waste treated by the facility. As an established regional waste treatment facility, it treats waste from the commercial sector too. The majority of recovered energy goes as steam to an adjacent fish feed factory, displacing fossil fuel previously used in its boiler and helping to support the local fish farming industry.
Engineered for low emissions
The patented gasification technology used by Energos is a two-stage process, which produces a syngas from waste in the first-stage gasifier. This syngas is transferred to the second-stage oxidation chamber, where it is fully combusted. Each stage can be individually controlled. And, because a syngas is produced, a homogeneous mixture can be burned to produce very low emissions - reaping the benefits of a simple, low-cost, dry flue gas system.
Another important aspect of the gasification units is their compact scale. A relatively modest building height of around 18m means the plant does not dominate the skyline. Just as importantly, local solutions for local problems offer greater opportunities to minimise traffic movements and can eliminate the need, and cost, of operating a transfer station - not to mention creating local employment for skilled operators.
In conjunction with an efficient recycling programme, the thermal treatment of MSW using advanced conversion technologies - pyrolysis, gasification and anaerobic digestion - is a highly effective solution. The technology enables electricity produced from MSW to be sold on at a higher price than electricity from non-renewable sources.
Feel the power
A single-line standard Energos plant has the capability to produce steam for heating, hot water or electricity production - in the case of electricity, around 3.1 to 3.5MWe, depending on the calorific value of the waste fuel. This would satisfy the needs of around 3,500 homes.
Gasification technology also provides additional benefits. Energy recovered from the biomass portion of waste (typically more than 60%) is exempt from CO2 emissions under the EU emissions trading scheme. From phase 2 of the scheme, companies should be allowed to trade the resultant CO2 credits.
The energy recovered from waste on-site will not be subject to the Climate Change Levy and will go toward energy reduction or efficiency targets. And, because the Energos process is an advanced conversion technology, the electricity produced from the organic content of the waste fuel will qualify for a renewable obligation certificate.
Nick Dawber is managing director of Energos