Castle Cement fuels general manager Dick Boarder says cement companies are under increasing legislative and economic pressure to increase efficiency and cut emissions. 'If the Climate Change Levy is imposed as set out in the last Budget it will cost the UK cement industry £40M a year,' he declares.
'We're already doing all we can to reduce our electricity consumption and have invested in new kilns and so on. But in the long run the CCL will lead to much higher usage of alternative, waste-derived fuels.'
Castle, of course, pioneered the use of the controversial 'secondary liquid fuels' at its Ribblesdale works in 1992. Basically organic solvents unsuitable for recycling, SLFs proved to be excellent fuels for cement manufacture. Emissions improved, cement quality was as good if not better. Last year Castle burned 70,000t of its specially-formulated Cemfuel at its Ketton and Ribblesdale works, and plans to increase this to over 80,000t this year.
Its policy received independent endorsement only two months ago, when the Environment Agency published two reports into the use of SLFs in the UK. These confirmed that SLFs were an environmentally friendly way of disposing of certain industrial wastes, and that the regulatory regime governing use of SLFs in the UK was stricter than in any other member of the EU. But this endorsement does not signal a vastly increased use of such fuels, Boarder says.
'We're approaching the peak of the Cemfuel usage curve, as there is simply not enough of it available to provide much more than 20% of our total fuel needs. If we are to hit our long term target of 60% alternative fuels we have to look at more available materials.'
Since May this year, when Castle's Scandinavian parent Scancem was sold to Heidelberger of Germany, the company has been able to compare its policy on alternative fuels with other Heidelberger companies in Europe and North America. 'At the moment the Belgian and German companies use more than us, the Scandinavians rather less,' Boarder reports.
'The Belgians in particular use a significantly different fuel mix, burning a lot of plastic waste and what they call Resofuel - which is basically SLF absorbed into sawdust to make a pelleted version.'
Belgian, German and American companies also burn old tyres. Calorific value is high, and the steel belts in most tyres provide the small percentage of iron needed for clinker formation.
Of the 35 million tyres discarded in the UK every year only about seven million are suitable for retreading. The rest go to landfill, but this represents a potential source of 350,000t a year of high quality fuel.
'The UK Government is very keen for us to use them as well,' adds Boarder. 'The UK has a target of recycling 65% of used tyres by the turn of the century, and by 2003 European legislation will ban the disposal of tyres through landfill.'
The problem this time lies in the logistics of getting the tyres into the kiln. 'Chipping them is expensive,' says Boarder. 'Using them whole means adding them one by one into the first, calcination zone of the kiln, which gives them plenty of time to burn properly.
This limits potential use to less than 10% of total fuel needs. The most promising alternative fuel now is what we call Profuel.'
Currently sourced mainly from the packaging industry, Profuel is made up from offcuts of plastic/paper laminates unsuitable for recycling and small scraps of low chlorine plastics such as polythene. 'We've also looked at the polypropylene fluff from carpet manufacture and had discussions with disposable nappy manufacturers about utilising their offcuts,' Boarder adds.
There are drawbacks. Density is low so storage areas are correspondingly large, and the material usually has to be processed down to 5mm particle size before use. But with 3Mt of packaging waste going to landfill every year, Castle's long term aim of using up to 50% of Profuel in any one of its kilns seems realisable.
Even more so than tyres, Profuel has a greater public acceptability than SLFs. This is particularly important since the latest protocol on the burning of alternative fuels was published by the Environment Agency in August (see below). While not objecting in principle to the requirements for increased public consultation, Boarder believes the protocol will discourage introduction of new alternative fuels.
'The Agency insists on every application for trials of a new fuel to be treated as a completely new application,' he says. 'So the entry costs of new fuels is high, which means that once we've got authorisation for a particular fuel at a works we really have to stick with it.'
Ultimately Castle hopes to achieve zero energy costs - as happens already in parts of Europe - with the cost of the conventional coal and petroleum coke fuels balanced by the 'gate fees' received for the disposal of tyres, Cemfuel and Profuel. Soon, Boarder says, Castle trucks delivering bagged cement will be returning with loads of tyres and baled Profuel. 'Every day we're besieged with calls from people wanting us to take old tyres. I just wish we could burn more.'