I-DEV0374: Request to skip the comparison between LFGtoal and (LFGelectricity + LFGflare)

1.Background information:
The project activity was registered on 30/11/2009 with methodology ACM0001 version 08. The project activity proposes to use LFG captured for power generation and flaring. There are three sets of power generator unit (PGU) and one flaring unit. In order to measure the LFG flow in main pipeline, to PGU and to Flare, 1 thermal mass flow meter (on the main line, as per required by PDD MP) and 2 vortex flow meters have been installed separately. The flaring equipment has been installed on-site, however not used during this monitoring period due to insufficient gas production. As per PDD MP, the comparison between (LFGtotal) and (LFGelectricity +LFGflare) is required for the conservative purpose of Emission Reduction calculation. However, with current existing system the comparison is not possible (as per the requirement of the MP of the registered PDD) and hence deviation is requested. The justification is presented as following.
2.Acutal measurement situation in the monitoring period (30/11/2009 –13/08/2010)
2.1: The LFGtotal is measured by a thermal mass flow meter. However, it was found during this monitoring period that the mass flow meter does not fit for the project activity due to the variation of LFG composition (methane concentration is not as stable as estimated).
The thermal mass flow meter installed on site is immersion type based on King’s law theory. According to the theory, two platinum resistances are used as sensor. One is to heat the gas flow to reach the design temperature (T1) and the other is to measure the flow temperature (T2), the gas flow could be calculated by the temperature difference (T) of T1 and T2 together with other parameters, as below:
(1)
Where:
P is the heat power,
T is the temperature difference of T1 and T2
Q is the mass flow of gas and F is a function
K1, K2, and K3 are the constants determined by gas physical properties, such as specific heat capacity, thermal conductivity, viscidity.
The K1, K2 and K3 will change with the variation of gas composition. From above formula we can see that the immersion type thermal mass flow meter is fit for the case where the gas composition is stable, otherwise, the gas flow could not be measured accurately.
2.2 Due to the insufficient LFG production, there was no surplus LFG sent to flare in this monitoring period; the value of LFGflare is 0. Therefore the comparison of LFGtotal and (LFGelectricity +LFGflare) will result in comparing LFGtotal with LFGelectricity only.
3.Content of deviation
Installed meter (immersion type thermal mass flow meter (for LFGtotal)) as per required by PDD MP, does not fit for this project activity (because of above reasons) hence a deviation is requested as following:
Only the data of LFGelectricity will be used to calculate the amount of LFG destructed by the project activity, and the comparison of (LFGtotal) and (LFGelectricity +LFGflare) will be skipped. This deviation is applied for to the period from 30/11/2009 to 13/08/2010.
4.Special remarks:
The client has changed the immersion type thermal mass flow meter (for LFGtotal) to a volume flow meter on 13 Aug 2010, in the next monitoring period, a revision of MP will be raised according to this change (in the registered PDD, it is mentioned that “a mass flow meter will be installed” for the LFGtotal, in the next monitoring period it will be updated according to the revision).
So this deviation is applicable only for the period from 30/11/2009 to 13/08/2010.

As per the registered PDD Monitoing Plan (MP), the LFGtotal,y is equal to sum of LFGelectricity and FLGflare. As indicated by the PP and verified by the DOE during onsite audit that due to insufficient gas production, the flaring equipment has not been used although it is installed on site as per requirement of monitoring plan. Regarding LFGtotal, as explained above, due to unsuitability of the meter (as required by PDD MP), a crsoo-checking is not possible. Therefore a deviation is needed due to deviating it from current PDD MP, and is confirmed that is a project specific situation. Whether this request for deviation is approved, a request for revision of the monitoring plan will be submitted in order to make compaliance this it with PDD MP in next periodic verification.
The deviation requested does not require a revision of monitoring plan or the changes from the project activity as described in the registered project design document. This is because the proposed deviation (skip the comparision) is only applicable to this first monitoring period.
As confirmed with PP, the client will submit a revision of MP for next monitoring period (for the period after 13/08/2010). The total flow meter (for LFGtotal) will be changed to volume flow meter, with this modification the comparision between the LFGtotal and sum of LFGelectricity+ LFGflare can be implemented as required by the applied methodology, so the deviation will not be required anymore in the remaining crediting period.

The proposed deviation is correct for this monitoring period. It can be justified as below.
In this monitoring period, due to insufficient gas production there were no flaring hence LFGflare = 0, so LFGtotal = LFGelectricity. Furthermore, accordng to the most recent version of the methodology ACM0001 (Version 11, page 15): “In the case where LFG is just flared, one flow meter for each flare can be used provided that these meters used are calibrated periodically by an officially accredited entity”, hence in the opinion of the DOE the same principle can be applied for LFG combusted in Generators.
For this project, LFGelectricity is measured by a vortex flow meter, which fits for the project activity. The flow meter is well installed in line with the relevant technical requirements and calibrated periodically by the certified third entity. The data generated by the meter is credible and accurate; therefore using those data to calculate the emission reduction is credible and accurate as well.
It is also noted that although the data measured by LFGtotal (measured by thermal mass flow meter) is not accurate enough to use, it is higher than the value of LFGelectricity (measured by the vortex meter), the request of ommiting the “comparison” in this monitoring period is appropriate and conservative.
Based on above considerations, it can be demonstrated that this deviation has no impact on the claimed emission reductions for the project during this monitoring period.