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Chlorine causing cost explosion
| | The PVC content in industrial waste used for energetic recycling will continue to increase. This makes chlorine a growing problem.
By Reinhard Schu, Managing Director of EcoEnergy Gesellschaft für Energy- und Umwelttechnik mbH in Germany
The chlorine content in waste and refuse-derived fuel greatly influences the running costs and availability of incineration plants. It is also the main parameter for calculating the capacity of the boiler and exhaust gas purification unit. The co-firing of refuse-derived fuel from mixed waste in the cement industry and in coal-fired power stations is presently on the decline due to increasing awareness regarding fuel composition and the usability of residual materials from power station processes.
The battle concerning the quantities of refuse-derived fuel that may either be co-fired with other fuels or fired in waste fuel incinerators and speculation on a lower recycling price for refuse-derived fuel have often led to an insufficient allowance for price risk factors.
photo: Pixelio
The PVC content will increase
Many exhaust gas purification units are designed for too low a chlorine content. The reason is because experience in waste incinerator plants over the past 15 years has indicated a tendency towards lower chlorine content. This is due to the reduction of polyvinyl chloride (PVC) in short-lived products and packing waste, which were previously disposed of as household waste. Even today, residual waste at 0.4 to 0.7% has a lower chlorine content than industrial waste with an average value of 2 to 2.5%.
With oil prices increasing in the long-term, plastics recyclates are also gaining in value. The more pure plastics are extracted from the waste, the higher is the proportion of PVC composites in the residual waste. This is leading to a sharp increase in the level of chlorine in industrial waste. With increasing CO2 certificate prices biomass materials, which are not recognised as such under the biomass regulations but are nevertheless CO2 neutral and usually have a low chlorine content, will be in greater demand in the cement industry and in coal-fired power stations. The proportion of fossil organics and therefore also of chlorine in refuse-derived fuel is going to increase.
Chlorine in waste
Approximately 60 per cent of sales revenues achieved by the German chemical industry are dependent on chloro-chemical processes. In terms of volume, PVC is by far the most common chlorine-based product found in large quantities in waste at the end of its functional life. It is assumed that waste or refuse-derived fuel contains approximately 0.3 to 0.4 per cent chlorine of either organic or diffuse origin, which cannot be separated using (dry) mechanical methods. The residual chlorine content consists mainly of PVC and other chlorinated plastics or rubbers.
During 2006 and 2007 a total of 75 samples of the waste input to various refuse-derived fuel processing plants were examined in the German state of Schleswig-Holstein. An average chlorine content of 2.2 per cent was determined. If one assumes a constant future recycling quota of 60 per cent for PVC and an increase of the PVC quantity in waste of 4 per cent per annum, the chlorine content in industrial waste designated for energetic recycling will increase to an average of 2.6 per cent by 2010 and over 3.2 per cent by 2015.
However, this estimate is valid only if the PVC industry actually succeeds in separately recycling at least 60 per cent of PVC waste and the proportion of biogenic material in the waste mix does not decrease. Otherwise an even higher chlorine content in the waste must be assumed. However, it is predicted that there will be a further reduction of biogenic material und increased recycling of non-PVC plastics, so that from 2015 waste for energetic recycling can include a chlorine content of over 5 per cent.
The PVC content in industrial waste will presumably not decrease in the foreseeable future. After calculating the costs arising from exhaust gas purification chemicals, increased residual material caused by residues from exhaust gas cleaning and through reduced availability and higher maintenance costs, the recycling costs are 400 to 700 euros per ton of PVC. The users of refuse-derived fuel can only induce suppliers to systematically reduce PVC content through a sensitive pricing policy, by passing on the actual costs caused by chlorine input and through introduction of a quality assurance system.
Responsibility of the PVC industry
“PVC only causes a marginal cost increase for waste incineration. It is therefore pointless to keep PVC waste out of incinerator plants or place a special surcharge on PVC products.” That is the comment made by the Consortium for PVC and Environment on their current homepage and it draws the conclusion that PVC does not represent a problem when incinerated.
According to current calculations made by EcoEnergy the additional costs involved in burning PVC in waste incineration plants or refuse-derived fuel power stations is 400 to 700 euros per ton compared to a basic price of approximately 100 to 300 euros per ton. This makes the disposal of PVC ten times more expensive than the disposal of household waste.
At present PVC disposal costs are equal to the production costs.
The volume of PVC waste for 2007 was calculated by EcoEnergy on the basis of figures on production and product life cycles provided by the PVC industry. According to this the quantity of waste is 1.1 million tons per annum, twice the quantity specified by the PVC industry. According to their figures 505,000 tons are disposed of as waste every year. Furthermore, a recycling quota of 75 per cent is implied. However, as last year a maximum quantity of 50,000 tons was actually recycled – disposal of PVC through a waste incinerator does not represent energetic recycling – the recycling quota for PVC waste according to this figure is less than 10 per cent.
Recycling of PVC from mixed collection is not to be expected in future either. There are no acceptable means of processing PVC to a degree of purity of over 85 per cent, which corresponds to the minimum requirement for material recycling. Energetic recycling of PVC is made very difficult not only by the high chlorine content of approximately 50 per cent, but also by the extremely high heavy metal content. According to the latest information, apart from chlorine, heavy metals such as lead and antimony play a significant role in the high-temperature corrosion which prevents the efficient energetic recycling of PVC waste.
If it is not possible to make a radical change in the quality requirements for plastics regarding “genuine recycling of plastics”, general reconsideration of the use of plastics is necessary. Even if new regulations on the quality of plastics with regard to their heavy metal content are introduced, the plastics put into general use up to this time are still not suitable for material recycling.
The functional life of many types of plastic is as high as 25 years. If the EU General Agreement on Waste Disposal is to be taken seriously, the plastics manufacturers will have to bear more responsibility for their products. On the basis of knowledge regarding pseudo-recycling of plastics, stricter product responsibility must be demanded of the PVC industry in order to meet national targets.
As it can be assumed that CO2 certificates will no longer be issued free of charge from 2013, the interest of coal-fired power stations and the cement industry in the biogenic content in waste will increase. Moreover, the biogenic refuse-derived fuels have lower chlorine and heavy metal contents than fossil plastic fractions. The CO2 emission potential of refuse-derived fuel is approx. 50 to 60 g CO2/MJ or 0.8 t CO2/t fuel at a heat value of 14 MJ/kg. With an assumed CO2 certificate price for 2013 of 50 euros/t of refuse-derived fuel, a price increase of 40 euros/t for combined incineration in coal-fired power stations or in the cement industry would be necessary.
Should trading with CO2 certificates be extended to include energetic recycling plants for waste products, as might be expected, this would also apply for energetic recycling plants operated according to the efficiency criteria of the General Agreement on Waste Disposal. Biogenic waste and biogenic fractions from bio-mechanical treatment plants will then be preferred for co-firing.
Simultaneously, attempts will be made to increase quantities of plastic recycling for suitable fractions when the prices for CO2 certificates and oil prices are raised. Through the extraction of recyclable materials and biomass, the remaining refuse-derived fuel quantity will decrease, the quality of this residual material will deteriorate and the chlorine content will increase further.
Influence of the amended EU General Agreement on Waste Disposal
The use of plastic waste in blast furnaces for chemical reduction or gasification for the production of methanol is not recognised as recycling according to the amended EU General Agreement on Waste Disposal. Due to its high chlorine and heavy metal content, energetic recycling of waste containing a high proportion of PVC is very sophisticated and actual energetic recycling can only be achieved in plants with a high degree of heat extraction.
In order to meet the recycling quotas specified in the EU General Agreement on Waste Disposal it is necessary to use well sorted plastics and other higher grade materials. PVC and thus chlorine continue to accumulate in the residual fraction for thermal disposal. The chlorine content will therefore continue to increase at an average of 0.1 per cent per annum.
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