Understanding CDM Methodologies - SuSanA

Monitoring of
Flare Efficiency
Project Developer
proposed Default
Values or Use of
Proxies
MP Rejection of
Proposal
Box 32: Measurement of the flare efficiency
Another outstanding issue that influenced the development of ACM0001 relates
to the requirement to measure the flare efficiency (i.e. the fraction of methane
destroyed within the flare) throughout the project cycle.
A request for revision 268 argued that the flare efficiency monitoring requirements
stipulated in ACM0001 269 posed several limitations:
1. Obtaining reliable and comparable measurements was problematic because
sampling of the exhaust gas could hardly be repeated under similar conditions.
2. Project participants generally face difficulties to regularly monitor the exhaust
gas of the flare due to the hazardous nature of the operation, the specialized
equipment required, the technical expertise needed, and the relatively
high costs involved, which often require project participants to hire foreign
consultants to perform the operation.
3. Because flares are designed to completely destroy the methane they receive, it
is unlikely that even highly precise equipment could detect remaining traces of
methane in the flare. It argued that available equipment is primarily designed
to detect traces of other exhaust gases (such as NO x
, SO x
, and VOCs) and
therefore may not be precise enough to efficiently detect traces of methane in
the exhaust gas.
Thus, two alternative methods were proposed to assess flare efficiency:
1. Use of default values: Pointing out that ACM0008 (for flares destroying coalmine
methane) and AM0016 (for flares destroying animal waste methane) both
permitted the use of default value to estimate flare efficiency (99% for enclosed
flares, 50% for open flares), DNV argued that landfill activities flaring methane
should be allowed to use the same default values as the processes involved are
not technically different.
2. Determination of flare efficiency using flame temperature and combustion
time: The submission also argued that increasingly, industrialized countries
allowed their methane-regulated industries to measure flare efficiency using flame
temperature, pointing out recent peer-reviewed studies showing a correlation
between flame temperature and methane destruction level. For instance, it
was raised that the Dutch government required a minimum flame temperature
of 900˚C to ensure an efficient combustion of methane, while other studies
suggested a minimum flame temperature of 760˚C. It was therefore proposed
that flare efficiency be determined using flame temperature, providing that a
curve correlating a set of combustion temperature values to a set of efficiency
values be made available to project proponents.
Though it recognized the difficulties related to measuring efficiency of open
flares, the MP rejected the request to allow project participants to use default
values to assess flare efficiency, arguing that these did not provide the level of
precision needed to accurately estimate the emission reductions. It added that
the efficiency of enclosed flares could be easily monitored at a relatively low cost.
However, the MP did not give any explanation as to why default values could be
used under ACM0008 and AM0016 and not under ACM0001.
Interestingly, the MP proposed a revision to ACM0001 – albeit unrelated to this
request for clarification – allowing project participants to use a default flare
efficiency value of 50% in cases where flare efficiency would deliberately not be
monitored. This recommendation indirectly contributed to eliminating certain
barriers faced by project participants operating an open flare system (as raised
by DNV).
234
See AM_REV_0012
235
ACM0001’s guidelines to assess flare efficiency allows for two different monitoring options: (1) continuous
monitoring of flare efficiency during operating hours; or (2) quarterly
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