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Energy grab from waste sent to landfill

As the world’s fossil fuel resources are depleted, we are facing a mounting crisis of energy supply. At the same time, global population growth and rising living standards mean that we are producing more waste than ever before. The world is, quite simply, facing a resource crisis – we have too much of one resource, and too little of another. Waste-to-energy technologies have an important role to play in resetting this balance. While advances have been made in recycling, waste is too often treated as a burden rather than a resource.

Advanced Plasma Power (APP), a UK-based waste-to-energy technology provider, has developed the Gasplasma system - a flexible and sustainable waste-to-energy/fuels process. Gasplasma’s potential is being demonstrated in the world’s first enhanced landfill mining project. This project, at the landfill site of Remo Milieubeheer NV in Houthalen-Hechteren, Belgium, will convert 16m tonnes of landfilled waste into recyclables and clean energy. It is a joint venture between APP and global waste management firm Group Machiels, and will use APP’s Gasplasma technology to convert the waste into clean, local energy and heat for nearby greenhouses. Once completely cleared, the site will be returned to nature.

The first stage of the Gasplasma process will see the landfilled waste sifted to remove any oversized objects. The remainder is then processed in a Materials Recycling Facility (MRF) to recover any metals, glass and hard plastics, before the residue is shredded and dried to make refuse derived fuel (RDF). The next stage comprises a fluidised bed gasifier which transforms the organic materials in the RDF into a crude or unrefined syngas (see box for an explanation of the Gasplasma process).

Removal of waste from landfill will cut greenhouse gas emissions from the site, and remove any risk of land and groundwater contamination. Gasplasma technology processes waste in an environmentally benign way - the only products are syngas, residual heat and Plasmarok. No emissions are released, and no toxic bottom ash is produced.

There are currently over 2bn tonnes of waste sitting in landfill sites across the UK. The long term trend of rising land prices provides a commercial incentive for freeing up this land, which in many cases is now close to centres of population as towns and cities have grown. Moreover, 2bn tonnes of waste has enormous green energy and resource potential. 

The Gasplasma process is not limited to landfill mining projects and APP is developing projects around the UK (and internationally) which will treat residual municipal and commercial solid waste before it reaches landfill. The potential for landfill diversion in the UK is considerable. landfill tax will reach £80 per tonne in 2014, and the government is committed to reducing the amount of waste sent to landfill under the EU Landfill Directive. Support is also available for renewable energy/fuels and/or heat generation from waste especially where this is undertaken using advanced conversion technologies such as Gasplasma. Despite these incentives, 55% of municipal waste generated in the UK is sent to landfill, compared to an EU average of 40%. There is both a carrot and a stick for communities and local authorities to invest in efficient waste-to-energy technologies.

A typical Gasplasma facility accepts 150,000 tonnes of residual municipal solid or commercial and industrial waste a year, enough to produce around 90,000 tonnes a year of RDF. This is enough to generate renewable power for around 17,500 homes, and residual heat for an additional 700. Moreover, Gasplasma offers a small-scale energy solution. A full-scale Gasplasma plant is around 15m high, meaning that it can fit into a standard warehouse, similar to the kind used for out of town business parks. A plant can be located unobtrusively on the edge of a town, taking waste from that town and supplying power and heat in return. The technology is also scalable, and can be supplied in multiple units to process higher quantities of waste, depending on the size of the community it serves. The Gasplasma process therefore provides a local, community solution to both local waste management challenges and sustainable energy requirements. 

In addition to the benefits to the local community, the business case for a Gasplasma plant is well supported. Gasplasma is more cost effective than the alternatives of landfill and incineration. The process is highly efficient, with high combined heat and power potential, enabling it to be operated at a cost that compares very favourably with other thermal waste treatment technologies. Incinerators produce around 20 to 25% ash which require transport, processing and disposal thus further impacting the cost and carbon footprint. The Gasplasma process produces no bottom ash; instead, waste products are vitrified into Plasmarok, which can itself be sold, delivering an additional revenue stream. Finally, as most of the equipment used in a Gasplasma plant will be manufactured off-site, a plant can be built and installed in 18 months compared to 24-30 months for an incinerator, which requires a substantial amount of on-site fabrication work.

The benefits and potential of the Gasplasma process are currently being demonstrated at APP’s plant in Swindon. This facility has been in operation since 2008 and is used to test waste feedstocks, helping to maximise the efficiency and for other development purposes. On a commercial level, APP currently has around 10 projects in the pipeline, all at various stages of development. Some have existing planning consent for gasification, while planning and permitting applications are in preparation for other sites.

The potential for the Gasplasma process as a gateway technology is enormous. APP recently announced a project with the National Grid to develop and demonstrate an end-to-end process that will use Gasplasma technology to produce bio-substitute natural gas (Bio-SNG) for injection into the national gas grid. It is estimated that bio-SNG could account for as much as one-fifth of the UK’s total heating requirements by 2050. Domestic heating alone accounts for over 35% of the UK’s carbon emissions - by producing gas from waste, the Gasplasma process could therefore contribute significantly to ‘greening’ the UK’s energy network. Another key area for development is the use of fuel cells to produce electricity either directly from the syngas produced by the Gasplasma process or from hydrogen (or bioSNG) derived from the syngas. APP is working with a number of partners to demonstrate these alternative uses.  

BOX OUT – how Gasplasma works

A full Gasplasma plant comes in four main sections:

1) a waste reception hall and Materials Recycling Facility (MRF);

2) the core Gasplasma technology consisting of the fluidised bed gasifier and plasma convertor;

3) gas cleaning equipment to cool, clean and condition the syngas;

4) a power island to generate renewable power directly from the syngas and recover residual heat.

The core Gasplasma technology is an internationally patented two stage advanced conversion technology (ACT). It combines two long standing and well proven technologies in a unique configuration to convert waste into a clean, hydrogen-rich synthesis gas (syngas).

The first stage is a fluidised bed gasifier (FBG) which transforms the organic materials in the RDF into a crude syngas containing tars and chars. It does this by heating the RDF to a high temperature, around 800oC, in a highly controlled reduced oxygen environment.

The crude syngas is then passed into a separate, secondary plasma converter (PC). The intense heat from the plasma arc and the strong ultraviolet light of the plasma ‘cracks’ the crude syngas. The cracking creates a clean syngas, while the bottom ash from the gasifier is vitrified into a product called Plasmarok.

The syngas is then cooled, cleaned and conditioned through wet and dry scrubbers before being used directly in a power island to generate renewable energy. Residual heat is also recovered from the process to be used in CHP mode within the process itself as well as for other users in the vicinity.

The cleaned syngas is used in a power island, consisting of reciprocating gas engines or gas turbines, to generate renewable power. Looking ahead the power island will comprise fuel cells or the syngas will be used to create synthetic natural gas or gaseous or liquid transport fuels.

Rolf Stein is ceo of Advanced Plasma Power

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