sectoral economic costs and benefits of ghg mitigation - IPCC

Terry Barker, Lenny Bernstein, Ken Gregory, Steve Lennon and Julio Torres Martinez
Sectoral Impact: Additional Comments 1
On the Presentation by Ulrich Bartsch
Methane leakage
Methane leakage was included in the model presented by U. Bartsch in equivalent to CO 2
emissions with respect to global warming potential (GWP). U. Bartsch has shown that this was a
limiting factor for gas development (half of the loss of growth in the gas sector would be from
this factor).
The gas industry has been investigating this topic rather extensively in the past years at regional
level (EPA/GRI, 1996) or global level (IGU, 2000). The main conclusions are the following :
• There is often a confusion between gas chain and oil chain: a very large part of gas is vented
or flared in the oil production sector but this was attributed to the gas chain (for example
IEA, 1997). An appropriate attribution of emission to the appropriate chain would reduce the
global CH 4 emission to 20 000 kt for a global production of 2,400,000 Gm 3 , i.e. 1,500,000 kt
CH 4 app. In percentage this is approximately 1,3 %.
• The main leakage or venting is found from production and the old town-gas network.
Transport systems, even in Russia and Ukraine, different from what was believed in the past,
and new plastic distribution networks have a low level of leakage.
• Therefore, gas development will decrease the rate of gas leakage because of the development
of modern distribution networks and transport systems even if the overall leakage is to grow
due to the substitution of coal and biomass or kerosene for households.
Another point concerns the global impact of gas leakage or GHG emission with respect to CO 2
emission factors in the combustion process. Leakage could reach approximately 9% and 5% at
which the comparative advantage of natural gas is suppressed in comparison with coal and oil
respectively. In electricity generation, taking into account the high efficiency of combined cycle
power plant, the break-even value is even higher. These break-even values are much higher
compared to the actual leakage rate.
Finally it is useful to note that other fossil fuels, and in some cases hydro energy, have their own
methane emission, which is important as mentioned above in the oil sector and comparable to the
coal bed methane in the coal sector. They are often in the same order of magnitude as in the gas
chain and should be taken into account in the model on their own respect too.
Therefore the impact of methane losses in the gas chain should be comparatively smaller.
Embedment of the CHG reduction process
The simulation analysis was oriented to climate change mitigation, for instance by inclusion of
methane leakage from natural gas. However, many decisions are taken at present on the basis of
what is seen as ancillary benefit. The local air quality (SOx, O 3 and VOC) and transboundary
acid pollution, for instance, are the main driving forces for fuel substitution of coal by oil and gas
or oil by gas, and for the shift from non-commercial biomass to fossil fuels in developing
countries.
1 These comments were received from Marc Darras after the meeting. Note that they are not incorporated
into appropriate sessions not only because of late submission but also because of extensiveness of coverage
of the topics and the inclusion of references.
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