No Rush to Implement BAT Conclusions for Waste to Energy Plants

IN DEPTH: The ‘Unsaid’ of the Waste Incineration BREF BAT Conclusions

With the Best Available Techniques (BAT) conclusions on Waste Incineration expected to be finalised this summer, Hubert de Chefdebien, Chairman of the ESWET Technical Working Group and Deputy-President of CEWEP, advises stakeholders against a hasty use of the BAT conclusions.

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Hubert de Chefdebien, Chairman of the ESWET Technical Working Group and Deputy- President of CEWEP, advises stakeholders against a hasty use of the BAT conclusions.

All installations included in the scope of the Industrial Emissions Directive (IED, Directive 2010/75/EU) must prevent and reduce pollution, use energy efficiently, prevent accidents and limit their consequences by applying the Best Available Techniques (BATs).

In order to define BATs and the BAT Associated Environmental Performance Levels (BATAEPLs) at European Union level, the Commission organises an exchange of information with experts under the coordination of the European Integrated Pollution Prevention and Control Bureau (EIPPCB).

The experts, nominated by Member States, industry and environmental organisations, are organised into Technical Working Groups (TWGs), one for each industrial sector covered by the IED. This process results in Bat REFerence documents (BREFs). The chapter containing the so-called BAT conclusions of each BREF is intended to be designed as a stand-alone document. After the Member States’ approval, the BAT conclusions, adopted by the Commission, are published in the Official Journal of the European Union as a Commission Implementing Decision, which is directly applicable without transposition.

Within 4 years of the publication of a decision on BAT conclusions, the environmental permits of all the installations involved must be adapted to the new requirements and, if necessary, retrofitting work must be done in order to ensure that BATs are implemented and, in particular, that Emission Limit Values (ELVs) are set to ensure that emissions do not exceed the BAT Associated Emission Levels (BATAELs). The BAT conclusions on Waste Incineration (WI) are currently being finalised and are due to be published in summer 2019.

Implementation Unclear
At first glance, the BAT conclusions seem quite straightforward. However, when the time for implementation comes it will be clear that there is a lack of background information on how to understand them, how to apply them and the applicability of the BATAEL ranges. In fact, BAT conclusions often do not reference other complementary legal requirements, nor is useful contextual information shared during the exchange within the WI BREF TWG.

There are a number of causes for concern in the Waste Incineration BAT conclusions. Very little information was collected by the EIPPCB on cross-effects and costs. BATAELs are based on data provided by operators of well-performing plants in response to a questionnaire. Most of the BATAEL ranges were defined by selecting some of the reported emissions (usually among the lowest ones) and substance by substance, independently of each other.

In the BAT conclusions, BATAELs are expressed as ranges, which are often wide. Very little information is provided on how to understand and use these ranges. It is important to note that none of the plants used to set the BATs/BATAEPLs were at the same time fulfilling the maximum performances of the BAT conclusions: the lower end of all BATAELs as well as the upper end of BAT Associated Energy Efficiency Levels (BATAEELs). Moreover, BATAELs are directly derived from operating values. When setting BATAEL-based ELVs, the need for a margin for operating contingencies and uncertainty has to be taken into consideration.

Operating Conditions
The IED defines BATAELs (see IED Article 3 (13)) and requires that ELVs be set by competent authorities to ensure that emissions do not exceed BATAELs. However, the IED does not mention the BATAEPLs (BAT Associated Environmental Performance Levels) that were introduced by the guidelines for the drawing up of BREFs (Commission Implementing Decision of 10 February 2012), which does not require them to be applied. Nevertheless, the WI BREF BAT conclusions do not say that the BATAEPLs it contains (BATAEELs, BAT Associated Energy Efficiency Levels) are not imposed by IED, as BATAELs are.

For future requirements regarding incineration ELVs, the legal picture will become twofold: a set of new BATAEL-based ELVs in Normal Operating Conditions (NOC) plus the existing ELVs in the relevant [A1] Effective Operating Time (R-EOT) for a number of continuously monitored substances.

Indeed, on the one hand, there will be BAT conclusions and their BATAELs. In accordance with the IED (Art. 3.13 and 15.3), BATAELs are defined under NOC (IED Art. 3.13) and future ELVs, which must be set to ensure that emissions do not exceed BATAELs, should also be established under NOC (IED Art. 15.3). This will apply to daily average values of continuously monitored substances and to periodically monitored substances.

On the other hand, the incineration sector is the only industrial sector for which compliance with the current ELVs (the ones laid down in IED Annex VI) of the continuously measured emissions is required within the EOT, i.e. as soon as and as long as waste is burning (see IED Annex VI, Part 8, Section 1.2). Therefore, the IED Annex VI ELVs will still apply in R-EOT (= NOC + OTNOC, Other Than Normal Operating Conditions) for daily averages and for half-hourly averages; see the summary of this dual requirement in Table 1.

Some points need clarification. The BAT conclusions do not remind the reader that BATAELs are defined in NOC. The IED does not define NOCs. There are a number of examples of OTNOC situations in the IED (Articles 14.1.f and 47) and in the BREF guidelines (Decision 2012/119/EU, in Section 4.6.2.2.3.ii and Section 5.4.7.2.6). For instance, OTNOC include start-up and shut-down operations, leaks, malfunctions, breakdown, regular maintenance and exceptional conditions (see Figure 1). The EIPPCB has said that the calculation and compliance conditions for BATAEL-based ELVs in NOC are not necessarily the same as the ones of IED Annex VI for EOT ELVs, but did not define these.

Uncertainty
The main concern is probably the uncertainty issue. The EIPPCB authors checked the Limit of Quantification (LoQ) for online instruments but did not take into account the overall uncertainty of measurements and, in particular, the significant part resulting from online calibration of instruments by control bodies, from the sampling system and of the Data Acquisition and Handling System. BATAELs are therefore expressed without information on uncertainty. The EIPPCB stated that the implementation of BATAELs to set ELVs and the compliance check is the Member States’ responsibility, which in fact allowed requirements on uncertainty to be completely disregarded during the BREF review.

A study conducted (within the context of the WI-BREF revision at the request of the professional associations CEWEP, ESWET and FEAD) by INERIS, the official French institutional expert on monitoring, was shared with the Technical Working Group, including the EIPPCB. It shows that the performances of the monitoring techniques available on the market, mainly the Standard Reference Methods (SRM), do not meet the requirements of the standards on monitoring made compulsory by the IED in respect of the maximum levels of uncertainty:

  • Already, for most of the controlled substances, at the level of IED Annex VI ELVs
  • A fortiori for the BATAEL ranges proposed in the Waste Incineration BREF draft, all of which are equal to or below the IED’s ELVs.

The incineration sector emissions are already the lowest of all combustion industries. If ELVs are lowered, the relative uncertainty will significantly increase, making compliance with standard requirements in respect of maximum acceptable uncertainty even more impossible to reach. No sufficient improvement is foreseen in the coming years to counteract this problem.

The situation can be tolerated for ELVs equalling or close to the IED Annex VI ELVs since operating values are in practice significantly lower than the ELVs. The margin between the two compensates for the fact that uncertainty is greater than required by the standards. However, for most pollutants, if the ELVs are set below the BATAEL upper ends, there will be no margin, or it will be insufficient to compensate, should uncertainties be higher than required (see Figure 2).

The extreme difficulty in performing meaningful Quality Assurance Level 2 (QAL2) calibration tests (defined by EN 14181 standards) when concentrations are very low and stable is well known (see Figure 3). It will be nearly impossible to properly calibrate the instruments in such cases with lower ELVs. The use of calibration gas will not help since it should be done close to the daily ELV level, which is often already impossible today at some Annex VI ELVs levels. Calibration gases at very low concentration with good accuracy are not available. Dilution introduces uncertainties. Reference materials are not available for some pollutants such as dust. Artificially high concentration in one pollutant (the span gas) will mask the interferences occurring between the different substances in the real flue gas.

In principle, the AMS’s readings, which are corrected according to SRM readings, are supposed to be correct. In Figure 4, the points are very close to each other and at very low concentration. This does not allow for any statistical reliable conclusion. On the right, the straight line obtained has a negative slope, meaning that, if it were to be used, the higher the value read by the online instrument, the lower the corrected value. As always with low and constant concentrations, both QAL2 tests passed the variability test, which validates them. This shows that the EN 14181 standards need to be revised.

One may consider that, to be on the safe side, it is appropriate to set ELVs at all BATAEL lower ends and at the BATAEPL higher end. However, as seen above, a certain amount of crucial information must be taken into account when implementing the WI BREF BAT conclusions. Setting ELVs based on BATAEL values that are lower than the upper ends of the ranges should require extreme caution. In fact the challenge does not relate to abatement techniques, which can meet very low emissions, but to providing evidence that the measurements comply with the requirements of the monitoring standards in respect of uncertainty.

For decades, the waste incineration sector has been the industry sector with the lowest emission levels by far and it has minimised the effect on the environment and on health. It is important to put these low gains into perspective and in relation to those, much higher, which could be obtained cheaply when dealing with other sources of pollution than the waste to energy sector in the same local context.

CEWEP, ESWET and FEAD are currently finalising an explanatory and guidance document to provide the background, to identify the concerns raised by the WI BREF BAT conclusions and to propose solutions. The pre-final draft is expected in June 2019.