CURVAS EVOLUTIVAS

The general wastes currently being landfilled are assumed to have a similar proportion of combustible materials to mixed municipal wastes and therefore considered suitable for conversion into a fuel. Generally such waste would undergo mechanical biological treatment to achieve the following output streams:

• 50% RDF/SRF

• 25% process losses • 5% metals

• 20% CLO/Aggregates/rejects

If it is assumed that all general wastes currently landfilled could be used to produce an RDF then an approximately 800,000 tonnes of RDF would be produced in the region.

The proportion of waste arisings attributable to each sub region is shown in Table 7.2. The information is used to apportion the 800,000 tonnes of RDF to the sub-regions according to relative quantity of waste arisings produced. The predicted waste arisings for MSW, C & I and C & D wastes for 2005/06 from the Regional Spatial Strategy were used to calculate the proportion of total waste attributable to each sub-region.

Table 7.2 Fraction of waste arisings and theoretical RDF production in sub-regions (using 2005/06 data from Regional Spatial Strategy)

Sub Region Fraction of total waste arisings RDF production potential (ktpa) Durham 20% 158 Northumberland 15% 120 Tyne & Wear 40% 324

Tees Valley 25% 197

Assuming the RDF has calorific value (CV) of 15 GJ/tonne and the average UK household electricity consumption is 4700 kWh/annum10 _{then the RDF created could produce enough}

electricity to meet the needs of 160,000 households. This is equivalent to production of just over 700 GWh/annum of electricity which represents 5% of the North East’s annual electricity consumption and 1% of the region’s overall energy consumption.

Even more energy could be recovered from this material if both heat and electricity were to be produced in ‘combined heat and power applications’. However, it is important to recognise that to make a ‘CHP’ project viable, the right kind of heat demand pattern, in terms of peak heat demand and any seasonal or daily variations, is needed close to the CHP ‘station’; and it is often difficult to find such a combination of good CHP characteristics at the right place.

Based on the data above, such RDF production would also require substantial new MBT capacity in the region (over 200 ktpa in Northumberland, over 300 ktpa in Durham, over 400 ktpa in Tees Valley and over 600 ktpa in Tyne & Wear), as well as the infrastructure or available markets to recover energy from the RDF. This would represent a significant investment in technology and infrastructure for the region. If the quantity of waste sent to landfill increases in the coming years, the potential quantity of RDF produced may also increase.

7.2.6 RDF Markets

Introduction

It is essential to realise that the production of RDF/SRF is only useful, from an energy perspective, if markets or technologies can be found to use the material as a fuel. The nature and composition of RDF can vary according to the feedstock used to produce it and it is likely that existing combustion facilities will require a certain specification of RDF to ensure that it does not introduce unacceptable technical or regulatory risks to their operations.

A number of potential uses for RDF/SRF exist around the UK. Foremost amongst these are large industrial energy consumers such as the manufacturers of cement, lime, paper and bricks, and the major consumers of fossil fuel in the power sector. However, there are barriers to the use of RDF/SRF in each of these potential industrial consumers:

Cement sector

The production of cement requires very high temperatures and residence times, making the cement production process suitable for using ‘waste’ materials as fuel. However, cement kilns prefer fuels with a high CV and a consistent nature, as an uncontrolled drop in process temperature can cause insufficient burnout and calcination, affecting product quality. Cement manufacturers have therefore preferred to use high-CV and homogeneous ‘waste’ fuels such as used tyres, for instance, rather than a lower-CV RDF/SRF. The cement sector is facing challenges relating to the emission of carbon dioxide, the price of fossil fuel has been very volatile in recent years, and the supply-demand economics of other waste fuels are shifting as the markets evolve. The opportunities for using RDF/SRF in this sector may grow in the next few years.

Lime sector

The market for lime in the UK is focused on its use in the soil, agriculture, food and pharmaceutical industries and as such has high quality standards. The use of RDF/SRF as a fuel in lime production may lead to contamination risks (or, at least, the perception of risk). There has been some limited interest in the lime sector for using ‘alternative’ fuels, but great care is taken over fuel characteristics. This means that fuel quality standards are likely to be an essential pre-cursor for RDF/SRF to find a market in this sector.

Paper sector

Pulp and paper mills require significant amounts of steam and power. Many mills generate steam for their process in industrial boilers. These boilers can use fossil fuels, wood and bark residues. Pulp and paper mills produce a large amount of their own by-products, and it can therefore be economically attractive to recover energy from such materials on site. Any market opportunity for RDF is therefore likely to be in remaining fuel requirements after on-site by- products have been used. However, recent evidence indicates that no UK pulp and paper mills have applied for authorisation to import secondary waste fuels, and only a few plants around the EU have.11 _{This indicates that most plants do not see utilisation of imported waste for the}

remaining fuel requirements as economically viable, commercially deliverable, or acceptable in planning terms. Nevertheless, such scenarios are possible in the UK.

Power sector

The use of RDF/SRF in power station boilers would require the power stations to be regulated under the Waste Incineration Directive. This would require a significant tightening of emission limits for some potential pollutants such as the oxides of Nitrogen, when compared with the current rules set out in the “Large Combustion Plant Directive” (under which power stations are currently regulated). Furthermore, there would be a much greater burden in terms of the number of exhaust gas components that would have to be monitored. As well as these ‘regulatory’ issues, there are also substantial technical challenges that would need to be overcome – coal fired power stations are designed to burn coal; gas fired power stations are designed to burn natural gas – neither type of technology is readily amenable to using RDF/SRF. There would need to be careful consideration of the modifications needed to a power station and of the possibility of putting a very large asset at risk, just to gain the benefit from a relatively small amount of RDF. Some perhaps easier technical possibilities do exist, such as burning RDF/SRF in a separate ‘EfW’ plant, and then combining the steam produced from this process with the steam in the established coal-burning or gas-burning power station, but even this is not without technical challenge. Also, the Renewables Obligation currently supports the use of ‘biomass’ (but not SRF-type wastes) in co-firing applications, but even this economic support mechanism will decline in the near future as the RO rules require a shift towards ‘energy crops’ away from other types of biomass material. All of these issues represent significant barriers to the use of RDF/SRF in UK power stations.

RDF Standard for Combustion Facilities

The European standards body, CEN, is developing a standard for SRF to enable efficient trading of SRF, to promote its acceptability on the fuel market and to facilitate a good understanding between seller and buyer. This is a work in progress and firm conclusions cannot be drawn from it yet.12

The proposed SRF classification system is based on three parameters that describe important SRF properties for combustion facilities including coal fired power stations, fluidised bed combustors and cement kilns. These parameters are net CV, chlorine content and mercury

11 _{Refuse Derived Fuel, Current Practice and Perspective, European Commission, Directorate General}

Environment Report B4-3040/2000/306517/MAR/E3, July 2003.

content and were chosen to represent measures of the economic, technical and environmental impacts of using SRF.

The development of these standards may help to create some activity in what is currently a nascent market for RDF/SRF, but as outlined above, the emergence of standards alone is unlikely to see rapid growth of an RDF/SRF market in the UK.