In March, the House of Commons Environment Committee strongly criticised the Agency's oversight of the growing number of cement kilns seeking to burn SLF (ENDS Report 266, pp 30-32 ). It expressed concern at the way in which the Agency's evolving BPEO assessment methodology (ENDS Report 249, pp 22-25 ) had been used to show that alternative fuels have no net adverse impact on the environment.
The Committee was impressed by local pressure groups' claims that the Agency has failed to require sufficient monitoring of adequate quality - with particular reference to Blue Circle's works (ENDS Report 263, pp 14-16 ).
In 1995, Blue Circle carried out three trial burns on one of the Weardale kilns with SLF replacing up to 40% of the normal fuel, a blend of coal and petroleum coke. Last October, it applied to the Agency for permission to burn SLF full-time on both kilns - claiming that the fuel "led to a significant reduction in some emissions and an overall improvement in environmental performance."
Blue Circle's application was backed by a BPEO assessment conducted by consultants ERM. ERM concluded that the "integrated environmental index" for the kiln's emissions fell from a baseline of 0.597 to 0.576 when SLF was used - an improvement of 3.5%. Most of the gain was due to reduced emissions of NOx and SO2, which outweighed an increase in deposition of metals to land.
The Weardale Action Group (WAG) responded with a detailed critique of the application. It complained that Blue Circle was "cherry-picking only the best results for report" - and that ammonia emissions, which increased when SLF was burned, had been excluded from the analysis.
Moreover, WAG noted, for several pollutants ERM had used "environmental assessment levels" (EALs) different from those offered by the Agency's draft BPEO methodology. The result was to increase the importance of reductions in NOx and SO2 - confirming the crucial importance of the EALs in applications of the methodology.
For nitrogen dioxide, ERM used an EAL of 50µg/m3 instead of the draft's 200µg/m3 - and for SO2 it used an EAL of 120µg/m3 instead of the EC standard of 80µg/m3 which applies when particulate pollution is low. WAG says that if the EALs in the draft methodology are used, the overall index for the kiln's emissions increases by 7% when SLF is burned.
In December - shortly after it was given a rough ride by the Environment Committee - the Agency sent Blue Circle a list of questions. It took up many of WAG's points, asked for a worst-case evaluation, and asked for the full report of trial monitoring data by Blue Circle's contractor CRE.
The company initially evaded the Agency's request that it reassess the data using the draft methodology's EALs. It also attempted, unsuccessfully, to keep CRE's report off the public register on the grounds of commercial confidentiality.
After further prompting by the Agency, Blue Circle provided a fuller response. This included calculations based on one trial burn using SLF with the maximum permitted levels of heavy metals and other compounds. On these data, the environmental index increased by 4.2% when SLF was burned - even using the favourable EAL for NO2 - mainly because of the increased deposition of heavy metals such as mercury.
Blue Circle realised that its application was in trouble, and on 26 March asked for a month's extension of the determination period. The Agency agreed to the request "reluctantly" - observing that the company's claim that SLF produced no net adverse effects remained "unproven".
The Agency expressed concern over "insufficient monitoring data of good quality" at 40% SLF substitution. It was unhappy that Blue Circle had relied solely on average emissions during the three trials, without taking full account of statistical uncertainty and variations in the data. Moreover, the company had not provided time-weighted average figures for continuous monitoring data, and many of its tests failed to measure heavy metals in the vapour phase - particularly important for mercury releases.
The Agency also drew attention to a "mismatch" between CRE's data and that collected by its own contractor, LTG-AE. In the final worst-case trial, LTG-AE measured emissions of several heavy metals - including thallium, antimony and tin - at least two orders of magnitude higher than those recorded by CRE. The Agency is still seeking an explanation for the discrepancies.
On 21 April, Blue Circle withdrew its application. Had it not done so, ENDS understands, the Agency would have refused to determine the application. Blue Circle says that it intends to reapply for further SLF trials at the site.
The saga casts serious doubts on Blue Circle's approach to monitoring and data handling. The company has recently been certified to the environmental management standard ISO14001 at all its manufacturing sites, including Weardale.
Inevitably, questions will also be raised over earlier decisions by HMIP and the Agency to authorise SLF burning at other sites. Sources in the cement industry say that the Agency has taken a tougher approach to the BPEO assessment at Weardale than at other kilns - and believe that the Agency's actions had been driven by a desire to head off the Environment Committee's criticisms.
The Agency's response to the Committee, to be published in June, is expected to clarify its approach to trials of alternative fuels. Its test protocol is likely to be made more prescriptive, with specified approaches to data handling, monitoring methods and requirements to consider worst-case scenarios.
Ironically, the final version of the BPEO assessment methodology, published in April (ENDS Report 267, pp 32-33 ), proposes an EAL for NO2 of just 40µg/m3 - which would have favoured SLF even more strongly in Blue Circle's calculations. The Agency wants to set up an expert group to advise it on setting EALs on a consistent basis.
In an echo of the Weardale case, the move was spurred by the Agency's disquiet over monitoring data from two trials at the site. In one trial, SO2 emissions increased significantly when tyres were burned. Blue Circle says it plans to apply for permission to carry out further trials at Westbury.
The company is currently carrying out a "demonstration of compliance" of SLF burning at its Masons works in Suffolk. It has also been burning small quantities of SLF at its Dunbar works in Scotland for nearly three years.