18:58 19 Apr 19
I-DEV0429: Deviation from the monitoring plan of the registered PDD: Change of monitoring frequency of parameters ‘heat rate’ and ‘combustion efficiency’
|Submitted by||DNV (16 Nov 2011)|
|Project activity||545: Durban Landfill-gas-to-electricity project – Mariannhill and La Mercy Landfills|
|Selected monitoring period||02 Nov 2007 - 28 Feb 2010|
|Title/subject of deviation||Deviation from the monitoring plan of the registered PDD: Change of monitoring frequency of parameters ‘heat rate’ and ‘combustion efficiency’|
The monitoring plan, as detailed in section D.2.2 of the registered PDD (version dated 4 May 2006), stipulates as frequency for the heat rate measurements of the generator ‘semi-annual, monthly if unstable’. However, the PP did not perform heat rate measurements during the monitoring period (02 November 2007 – 28 February 2010). The monitoring plan, as detailed in section D.2.2 of the registered PDD (version dated 4 May 2006), stipulates as frequency for the combustion efficiency measurements of the generator, ‘semi-annual, monthly if unstable’. However, the PP did not perform combustion efficiency measurements during the monitoring period (02 November 2007 – 28 February 2010).
Hence the current request for deviation pertains to the period from 02 of November 2007 to 28 February 2010 for the two above mentioned parameters.
It is to note that this request for deviation has been updated to address the concerns of the secretariat on its previous incomplete message, and is therefore being resubmitted.
For the relevant monitoring period (02 November 2007 – 28 February 2010), the deviation does not require a request for revision of the monitoring plan, as it concerns the past and the heat rate established in November 2010 and final measurements related to the combustion efficiency in April 2010 are covered by the request of revision of the monitoring plan and change of PDD.
It must be noted that the PP has already submitted, with the appropriate justification, a request for revision of
the monitoring plan (along with the submission of notification of changes to the PDD, submitted on 1 July
2011) to reduce the required frequency for measuring heat rate and combustion efficiency to less frequently than semi-annually. This is in accordance with the VVM v1.2, paragraph 201, mentioning that ‘if during verification, the DOE concludes that the monitoring plan is not in accordance with the monitoring methodology, the DOE shall request a revision to the monitoring plan prior to concluding its verification and making its certification decision’. Furthermore, during the Meth Panel’s 53 meeting, held from 31 October 2011 to 4 November 2011, and as mentioned in the meth panel meeting report paragraph 26 b, the meth panel requested the EB to take note that the alternative approach by the project participants for the monitoring and determination of the parameters “Combustion efficiency” and “Heat rate of the generator” is technically acceptable.
Therefore, even though a revision to the monitoring plan is underway to reduce the required frequency for both heat rate and combustion efficiency to annual measurements (which will be subsequently applied for following verifications starting from 1 March 2010), this request for deviation is pertinent as no measurmenet was taken by the PE for periods prior to 28 February 2010.
For the heat rate:
The first testing of heat rate has been undertaken by Envitech Solution (Pty) Ltd. in November 2010 (see Attachment 2). As no heat rate values have been measured during the monitoring period from 02 November 2007 to 28 February 2010, the PP has used heat rate values provided by the technology provider, upon commissioning of the equipment, as the basis for the calculations. As explained in Attachment 1, a calculation of heat rate using the engine power output and the engine manufacturer performance data is carried out every 15 minutes within the SCADA data capture system. These values are then aggregated over each day of operation to derive a single value which is used in the calculation of emissions reductions. Attachment 1 also includes the original letter from the engine manufacturer (GE Jenbacher letter dated 23 January 2007) on which the calculations are based.
The registered PDD (version dated 4 May 2006) referenced a heat rate value of 14 000 kJ/kWh. This figure was based upon a worst case for a 0.5 MW engine (www.chpcentermw.org/pdfs/toolkit/rules_of_thumb.pdf , BTUs were converted into kJ).
By using the initial values from the technology provider (GE Jenbacher letter dated 23 January 2007) as the basis for the calculation of the heat rate (see Attachment 1 for details of the equation used), the resulting emission reductions from electricity production (using the primary method as explained on page 22 of the PDD) are essentially lower (given the multiplication by a smaller heat rate), i.e. more conservative, than would result from using subsequent field testing data performed in November 2010 by Envitech Solution (Pty) Ltd. at equivalent load.
The results from subsequent field testing data showed as expected a higher heat rate than the heat rate stated by the technology provider due to the fact that heat rate tends to increase over time. This is demonstrated in Attachment 2, showing the results of two field tests which, at an engine output of 800 kW produced a heat rate of 8 923 kJ/kWh using recorded data from the plant instrumentation and 9 107 kJ/kWh using recorded data from manual instruments. If the power output within the SCADA system was recorded as 800 kW, a heat rate of 8 799 kWh would be used in the calculation of emission reductions. This is conservative, as it would result in a lower energy input to the engines and less emission reductions from electricity production (primary method), which is conservative.
In addition to the above, it is known that due to wear and tear of the combustion engines, the heat rate value tends to increase slowly with time. This has been confirmed by the PP during engine tests in November 2010 (see Attachment 2), the reporting of which will be included in the monitoring report. In the test carried out in November 2010 it is confirmed that the heat rate from actual testing at the plant is 1.41% higher than that established by the manufacturer. Furthermore, the heat rate calculated as a check using data recorded from manual instruments is 3.50% higher than that established by the manufacturer. By using the lower, initial value (from the technology provider) as the basis for the ER calculations, the DOE confirms that the PP applies a conservative calculationapproach, as the ‘primary calculation’ method (p 22 of the PDD) implies a backward calculation departing fromthe amount of electricity generated.
Therefore as shown in the example spreadsheets, since essentially the electricity generation is being multiplied by a smaller constant: 8 799 kJ/kWh (manufacturer’s data) as oposed to 8 923 kJ/kWh (field test result), the emission calculations are being reduced by (8 923-8 799)/8 923 = 1.4%. Hence with the proposed deviation the effect on emission reductions is a reduction of an estimated 1.4% or, referring to the attached example month February 2010, ER are reduced from 1 784 tCO2e to 1 759 tCO2e (using the primary method).
For the combustion efficiency:
The first testing of engine methane destruction efficiency for the engine installed at the Mariannhill landfill site was carried out by SGS on 13 April 2010. The test resulted in an efficiency > 98.6% (see Attachment 4). The fact that no combustion efficiency data are available during this monitoring period, does not impact ER calculations, as it is actually not required in the formulas to calculate emission reductions. However, as the parameter is mentioned in AM0010 (presumably for reasons of crosschecking the efficiency of the conversion of methane to carbon dioxide), and accordingly mentioned in the registered PDD (version dated 4 May 2006), the parameter is expected to be monitored. The fact that during the monitored period the combustion efficiency was not monitored is not deemed problematic by DNV, as the combustion engines were still new during the monitored period, and as the site visit indicated that maintenance was properly implemented.
Moreover, it is known that there is a correlation between heat rate and combustion: when combustion efficiency decreases, heat rate values tend to increase. Hence if there would have been a problem with the combustion efficiency, this would not have gone unnoticed during the heat rate measurements which took place in November 2010.
In Attachment 3, the relationship between time, engine efficiency, and maintenance is substantiated by the technology provider, confirming that the engine heat rate will slowly increase over time, relative to what it was initially when each engine was first installed. This is due to the normal wear and tear of the engines. After maintenance, efficiency will improve but not necessarily to the original level.
Attachment 3 also explains the relationship between combustion efficiency and heat rate value, in that due to wear and tear, the heat rate will slowly increase and the engine combustion efficiency will concomitantly gradually reduce over time.
The above explanations, and the supporting evidence provided by the PP, confirms that the failure to monitor engine heat rate and combustion efficiency during the monitoring period, has no impact on the calculation of emission reductions and that the measures adopted are conservative.
Hence, there is no effect on emission reductions as a result of the deviation for the monitoring of combustion efficiency. It is expected that from the next monitoring period onwards the PE will monitor this parameter once annually.
Reference is also made to the almost identical request for deviation submitted and accepted under reference number I-DEV0397 (http://cdm.unfccc.int/Projects/deviations/57953 ).
|Link to the documentation made available at validation stage or monitoring report||Link to relevant documentation|
|Signed form||Signed form (1060 KB)|
This request for deviation has been accepted.
The Chairs have accepted the proposed request for deviation to the monitoring and reporting process for the second monitoring period from 2 November 2007 to 28 February 2010.
|Current status||28 Dec 2011 - Deviation accepted|
22 Jul 2011 -
21 Aug 2011 - Submission deemed incomplete
16 Nov 2011 - Resubmission received
30 Nov 2011 - Successfully passed the Completeness Check
12 Dec 2011 - Awaiting EB decision