UK set for world first gasi plant

CONSTRUCTION has begun in the UK on a new world-first commercial-scale ‘green gas’ plant that will gasify household waste into fuel.

The plant is set to begin operation in 2018 converting up to 10,000 t/y of waste collected locally from around the plant in Swindon into so-called bio-substitute natural gas (BioSNG). This can be distributed through the gas grid for use in existing appliances such as boilers and cookers, as well as in transport.

The company that has helped develop the process – Advanced Plasma Power – says it represents a major step forward in decarbonising the energy system.

“Whilst the power generation sector has made huge progress towards decarbonisation in recent years, decarbonising heat and transport – worth 74% of energy usage – has proved a more stubborn challenge, and is an established government priority,” Advanced Plasma Power said in a statement.

A technical study into the technology’s commercial viability, estimates that if implemented nationwide, it could fulfil one third of the country’s annual heating requirements or power all of the UK’s heavy goods vehicles.

The technology has been developed at a £5m (US$6.2m) pilot plant in Swindon, a joint venture with National Grid and Progressive Energy. The new facility, which will produce enough gas for 1,500 homes, will cost £25m to construct, and is jointly-funded by the project partners as well as grants from the government and Ofgem.

“Advanced Plasma Power is delighted to be commencing construction of the world’s first commercial gasification plant to produce green gas from household waste. As our technology matures we will be able to convert waste into fuels cost competitively with fossil fuels, helping to achieve an affordable, secure and sustainable low carbon future,” said Advanced Plasma Power CEO Rolf Stein.

The process for producing the gas begins with shredding the household waste, removing recyclable material and drying it. The waste is gasified at around 800?C using a fluidised bed gasifier supplied by process technology developer Outotec. This syngas is then passed to a secondary conversion unit where the strong ultraviolet light and intense heat of a plasma arc results in the complete cracking of tars contaminating the syngas.

The syngas is then passed to a waste heat boiler where its temperature is reduced from 1,200?C to 200?C, and then passed through a series of gas cleaning stages to remove heavy metals, acid compounds and ammonia. From here, the syngas is compressed to 12 bar and goes through a series of catalysed reactions to remove contaminants to levels measuring in the parts per billion, and then passed to water-gas shift reaction, adding steam generated from revered heat to increase the ratio of hydrogen to carbon monoxide. A methanation step reacts the carbon monoxide with the hydrogen to create methane, which is then ready to inject into the gas grid, and carbon dioxide which is sold to industry.

“This is an exciting project which addresses the need to reduce emissions from heat and transport. BioSNG provides a non-disruptive and affordable solution to deliver carbon savings now, and provides a pathway to deeper potential reductions through hydrogen production,” said Chris Manson-Whitton from Progressive Energy.

The push for green gas follows the news earlier this week that UK energy firm Ecotricity said gas from grass could offer a green alternative to fracking, and will offer to build its anaerobic digestion plants in communities opposed to the contentious technique. The company says that building 5,000 anaerobic digestion facilities, which would process locally-sourced grass into biomethane for injection into the grid, could provide the gas needs of 97% of the country’s homes by 2035.