REVIEW REPORT FOR NEW ZEALAND (EXAMPLE)

C. Key categories
1. Stationary combustion: gaseous fuels – CO₂
32. New Zealand uses relatively high values of CO₂ EFs for natural gas (58.7 t/TJ). For 1990 and 1991, they are the highest of reporting Parties and are higher than the IPCC default value (56.1 t/TJ). New Zealand Energy Information Handbook (Baines, 1993) contains typical chemical compositions for natural gas sales streams of the different local gas fields, indicating relatively high concentrations of ethane (3.8 to 11.2 per cent by volume) and propane (2.9 to 11.7 per cent by volume). This information source also indicates that the majority of the natural gas that is distributed in New Zealand has a CO₂ concentration of about 4 per cent. Typical compositions of New Zealand’s natural gas from the two main gas streams (Maui and treated gas from Kapuni) for different years in the period 1997–2000 are in line with those reported by Baines (1993) and also with the EFs reported by New Zealand in the cited period. The ERT recommends that New Zealand collect and archive the natural gas composition that is used to estimate CO₂ EF each year. The ERT encourages New Zealand to include a brief discussion of the chemical compositions of the two major gas streams and its influence on the relative high value of the CO₂ EFs.

33. The NIR reports that the relative proportions of the Maui and treated gas from Kapuni that are input to the distribution system are assumed to be 50/50 for the period 1990–2004. The Energy Data File (September 2006 edition) reports the annual production of the local gas fields for the period 1970–2005, and the relative proportions actually produced deviate from the assumed 50/50 share. The ERT recommend that New Zealand use this information to estimate average annual CO₂ EFs that are more representative of the actual conditions.