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Title:
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Validatie van de methaan-emissie-reductie op stortplaats Nauerna
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Author(s):
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Published by:
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Publication date:
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ECN
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1-6-1998
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ECN report number:
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Document type:
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ECN-C--98-052
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ECN publication
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Number of pages:
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Full text:
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33
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Download PDF
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Abstract:
Methane emission measurements were performed at a landfill site locatedapproximately 20 km west of Amsterdam, Netherlands. These measurements aimed
to determine the emission level of the 60 ha landfill site after the
implementation of a gas extraction unit. In order to assess the emission, the
concentration levels in the plume downwind of the site were determined using
a Tuneable Diode Laser Atomic Spectrometer mounted in a small truck. This
measurement system combines a high selectivity for methane (or nitrous oxide)
with a high time resolution (up to 20 Hz is possible). The position of the
truck was determined using a differential global positioning system (DGPS)
that uses up to 8 satellites to retrieve the position. Meteorological
measurements were obtained using an ultrasonic anemometer located on top of
the landfill. The concentrations measured on transects through the plume that
run about 780 m downwind of the centre of the landfill were compared with
modeled concentrations. The model divides the landfill area into 100 point
sources and calculates a gaussian plume for each point. The source strength
is estimated by making a match between the measured and modelled
concentrations in the plume. A validation of the model was done by releasing
a tracer (nitrous oxide) from a known location on the landfill. The TDLAS is
capable of measuring N2O simultaneous with CH4. A total number of 14
transects have been obtained. For 11 transects plumes were found. The
emissions that were estimated ranged from 19 gCH4.s"-"1 to 40 gCH4.s"-"1
with one extreme value of 65 gCH4.s"-"1. The best guess for the average
emission was estimated to be 31 #+# 13 gCH4.s"-"1. In 1997 the same kind of
measurements was performed to evaluate the emission level before
implementation of this extraction system. In that campaign 8 plume
measurements were obtained, which resulted in a best guess for the landfill
emission of 62 #+#12 gCH4.s"-"1. The conclusion is that a reduction of
about 50% of the emission has occurred. This is partially due to the
reduction of the emission because of the extraction system, the other reason
is that the CH4 production inside the landfill (estimated using CH4 formation
models) is decreasing. The decrease estimated from the formation model
estimates and the production figures of the extraction system indicate a
smaller emission reduction than observed from the measurements. The
difference is not alarming facing the uncertainty both in the measurements
presented here and the uncertainty in the production estimates
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