scope:

For a comparative energy-related assessment of emissions during thermal waste treatment, it is necessary to define a balancing method with specified balance spaces and cover all the incoming and outgoing substance and energy flows required for balancing [4; 28; 30; 38]. This then permits an unambiguous energy- based assessment of emissions from thermal waste treatment in comparison with other processes of energy or substance conversion. If the concept of emission is extended to climate-affecting substances, it becomes easier to assess the positive and negative effects of the combustion and substitution of fossil energy carriers on the CO₂ balance.

As conventionally practised in process engineering, characteristic values will be used for the comparison of energy conversions and examples of them will be documented for the types of thermal waste treatment plant in operation.

In this way, it is possible to assess the useful energy yielded by thermal waste treatment and the substitution of primary energy carriers achieved as a result [32; 34; 35]. In order to demonstrate the plausibility of the calculations, the annex gives quantified examples of an existing incineration plant.

Furthermore, the issue of distinguishing between energy recovery from waste and the disposal of waste, which was recently raised in connection with the ruling of the European Court of Justice [2; 42], is now addressed by the present standard.

This standard refers to the methods of the following VDI Standards:

• VDI 3460 Part 1
• VDI 4600
• VDI 4600 Part 1
• VDI 4660 Part 1
• VDI 4660 Part 2
• VDI 4661

Above and beyond uses in the calculation of energyspecific emissions, the balancing of substance and energy flows in the thermal treatment of waste is gaining in importance in several other respects. A growing number of examples of mono-incineration plants in particular can be found in the literature.

For this reason, the European Commission, represented by the European IPPC Bureau, has devoted two chapters of its extensive Best Available Technique Reference Document (BREF) to the subject of energy efficiency in thermal waste treatment.

This procedure is described in the Waste Incineration BREF. There are several publications on its application (e. g. [20; 25]). The calculation is based on formalized treatment of the conventionally available energy- relevant data, defines exhaustively the integration and assignment of the parameters and supplies the calculation formulae. Essential for correct application are agreement on the system boundaries and a detailed understanding of the process or plant in question. Failing this, erroneous assignments and omissions can yield different results.

The debate on the demarcation of energy recovery from waste from the disposal of waste initiated by the rulings of the European Court of Justice [2; 42] has encouraged the balancing of energy flows so that the treatment method can be classified as "recovery" or "disposal" in each case. For the assessment of this issue, it is absolutely essential for the balancing boundaries to be clearly defined with the aid of schematic diagrams of substance and energy flows for the plant in question in conformity with the plant configuration (e. g. [4; 6; 30; 31; 32]).

In a proposal submitted by the European Commission for a directive of the European Parliament and of the Council of 21.12.2005 (Waste Framework Directive 2006/12/EC), an equation for calculating energy efficiency is presented. In its present form, this calculation and assessment method does not comply with the rules for the calculation of energy efficiency [38]. At the time of the passing of this VDI Standard (December 2006), it was still the subject of a heated political debate [39; 40; 41] and has not therefore been adopted in this standard as an established state of the art.¹⁾

It should also be mentioned that, for the industrial monitoring and the optimization of treatment processes, substance and energy balances are required to permit the continuous calculation of characteristics (e. g. calorific values or efficiencies) in ongoing operation (e. g. [6; 19; 33]).

¹⁾ The state of the art, based on the discussion that is mentioned here, is described in VDI 3460 Part 1. Because the appropriate political formula does not apply to the application of this standard, the content persists without any changes at that point.