Raw natural gas is generally piped from production wells to processing and straddle
facilities where impurities, and byproducts such as natural gas liquids, are removed.
Commercial natural gas is approximately 95% . The remaining fractions are higher
hydrocarbons such as butane, and propane, and trace impurities.
As mentioned earlier, methane, upon combustion, produces carbon dioxide and water
vapour .A number of agencies and private organizations track global GHG emissions. There
is some variation in the estimates between sources, but they are all generally within
reasonable ranges of each other. The World Resources Institute (WRI), for example, has
estimated for 1991 that global methane emissions totalled 270,000 Kr, with livestock and
wet rice agriculture contributing 81,000 and 69,000 Kr, respectively, worldwide. North and
Central American methane releases for both oil and gas production combined are estimated
by WRI at 8,200 Kt or about 3% of the global methane total. Based upon the CGA studies,
the Canadian gas industry (all sectors) would account for 915 Kt or 11% of the 8,200 Kt.In
early 1997, the US Environmental Protection Agency (EPA) and Gas Research Institute (GRI)
published results of a four-year study of methane emissions from the US natural gas
industry. The study concluded that methane emissions from natural gas operations in the US
were 1.4% of (gross) production. With Increasing production of natural gas, the study also
indicated that future emissions would be between 0.4% and 1.0%, because of cleaner
technologies coming into service. Radian, which did the study for EPAIGRI, reported the
emissions as 1.68% of "marketable production." This figure is consistent with
the 1.4% figure if it is assumed that 15 to 20% of US gross production is natural gas
liquids, extracted near the production site.As indicated in Tables 4 and 5, Canadian
methane emissions from natural gas end use are negligible when compared to that emitted
from operations within the natural gas industry. While absolute
methane emissions volumes continue to increase
because of Increasing demand and use of natural gas, improvements are
oceurring on a unit of production basis, as illustrated in Table 7, which also indicates US
1992 values (using similar methodology).
A reduction in emissions on a percentage of production basis is noticeable between 1990
and 1995. It should also be noted that comparison on the basis of pipeline length shows
virtually no change in emissions between the two marker years even though 1995 saw an
increase in pipeline kilometres of over 11% compared to 1990
From Radian & Marbek, with N,O added for
industry section. GWPs: CH4 21, N20
310. N2O for industry taken at 1.053% of NOx
figures in Radian (same as end-use
percentage). NRCan Figures taken from Tables C.24 to C.27 in NRCan’s Energy
Outlook
2020. "Stripping" figures result from removal of natural gas liquids from
natural gas.
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