Mass burn incineration plants, with their towering chimney stacks, can be an unpopular choice for the communities that surround such facilities. However, an alternative energy-from-waste (EfW) solution is the use of steam.

Steam eliminates bacteria and reduces the waste volume by 80%, finally yielding a combustible fibre for conversion to energy including electricity. And it has proven useful in the manufacture of other recycled products.

There has been a small nucleus of steam boilermakers that have survived over the past three centuries. These companies have provided plant to distilleries, breweries, food processors, hospitals and other processes.

One contender in the market is KP Wellman’s Steam Treatment & Recycling (Star) system. The Star system can handle up to 300,000 tonnes a year at a site. It takes unsorted municipal solid waste and treats it with high-pressure steam, which breaks down the waste and sanitises it.

Once treated, the recyclable materials, ferrous, aluminium, plastics and glass are easily extracted and baled. The residual putrescribe or fibre is then processed as a fuel to generate electricity and sold back into the National Grid.

Maximising extraction

Kerbside separation of materials is complimented by the Star system making sure that every recyclable resource is extracted. If metal or glass goes through the autoclave, it is completely sanitised and ready for smelting and casting.

For example, the process takes in food cans, or jars, destroys the bacteria and strips off all the labelling, leaving the bare clean metal or glass ready for recycling.

The Star system – unlike an incineration plant – requires only a low-profile, small footprint, building that will have a smaller impact on the landscape. This should make it more acceptable to the local community and their environment. The Star system is modular in its design and gives several options for the method by which it transforms residual waste into energy.

These methods include: being fired on a boiler that produces steam for a turbine that generates electricity; co-firing (with coal) to generate power; firing through a gasifier to an engine that generates electricity from Syngas.

>Peter Lawrence is group managing director of KP Wellman

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