5. ESTUDIO TÉCNICO
5.3 ALTERNATIVAS DE LOCALIZACIÓN
10.3.1 Transmission
Key performance indicators for transmission pipelines are capacity, network integrity, reliability and safety.
AEMO has identified that while gas reserves are sufficient to meet annual demand projections to 2029, including LNG export, the increasing demand for gas will place pressure on the transmission pipelines and production infrastructure used to supply gas.698 In NSW, as the winter peak demand
is around 50% higher than summer peak days, winter is the period in which demand will first exceed supply. AEMO estimates that the capacity of pipelines serving NSW will be exceeded from 2012 under winter peak day 1 in 20 POE conditions and from 2018 under 1 in 2 POE conditions.699
will be exceeded. A forecast 1 in 20 POE maximum demand figure will, on average, be exceeded only one year in every 20. The demand supply balance is illustrated in Figure 10.9.
Figure 10.9: Moomba–Sydney Pipeline and Eastern Gas Pipeline winter 1 in 20 POE forecasts700
The Energy Branch of Industry and Investment NSW produces a yearly performance report on the performance of NSW licensed pipeline operators in implementing the safety management systems required by the Pipelines Act 1967. There are 31 currently-operating pipeline licences, which include both major transmission and other pipelines defined in the next section as distribution assets. Table 10.16 identifies the trends in pipeline safety descriptors. It shows that the safety has not changed significantly over the last four years.
Table 10.16: Safety descriptors of licensed pipelines701
Year Near miss
per 1,000km Incidents per 1,000km Loss of containment per 1,000km Ignitions per 1,000km Damage per 1,000km 2005/06 1.77 0 0.22 0.22 0 2006/07 0.41 0.83 0 0 0.41 2007/08 2.27 0.62 0.21 0 0.21 2008/09 2.05 0.62 0.41 0 0 10.3.2 Distribution
In assessing the performance of a gas distributor network, it is necessary to consider multi-year trends rather than single years. This is because gas distribution infrastructure is sensitive to environmental conditions, such as heavy rain entering low pressure pipes, and the renewal program, which increases the number of planned interruptions in the short-term but reduces them significantly in the medium to long term.
Two key factors in assessing the quality of a distribution network are reliability and network integrity.
Reliability is measured in terms of the average frequency and duration of supply interruptions, which can be either planned or unplanned. Planned interruptions occur when a supply is
deliberately disconnected to undertake maintenance or construction work. Unplanned interruptions mainly occur because of leakages or damaged pipes requiring immediate repair. Unplanned outages are often caused by third parties damaging pipes, or by water entering low pressure pipes.702 Key reliability measures are:
System Average Interruption Duration Index (SAIDI). SAIDI measures the total minutes, on
average, that a customer could expect to be without gas over the reporting period. Total SAIDI comprises both planned and unplanned minutes-off-supply.
System Average Interruption Frequency Index (SAIFI). SAIFI measures the number of
occasions per year when each customer could, on average, expect to experience an
interruption. It is calculated as the total number of customer interruptions, divided by the total number of connected customers averaged over the reporting period.703
Planned interruptions are mainly due to mains replacements. Unplanned interruptions are due to third party damage, infrastructure failure and inadequate maintenance/installation.
Figure 10.10 compares SAIFI figures of Jemena Gas Networks (NSW) (JGN) and ActewAGL’s networks to other distribution networks around Australia.
Figure 10.10: SAIFI for network around Australia704
Network integrity can be measured by the quantity of leaks (loss of containment) and unaccounted- for gas. Levels generally reflect the distributors’ quality of operational and maintenance activities. Figure 10.11 compares all leaks per kilometre of mains for distributors around Australia.
Figure 10.11: All leaks per km mains for distributors around Australia705
Unaccounted-for gas (UAFG) is a measure of the difference between the gas entering the system and the amount delivered. This difference indicates how much of the gas injected into the network is lost in transit. This can be due to system leaks, theft, inaccurate meters, differences in times that meters are read, accounting errors, gas compressibility factors, temperature or heating value discrepancies, line pack differences, and losses in commissioning of new or replacement pipes.706 It
is estimated that approximately 80-90% of the UAFG can be attributed to gas leakage.707 Table
10.17 identifies the volume of unaccounted-for gas for NSW networks. The decrease in UAFG over the last two years is primarily due to the reduction in accidental damage to network assets caused by third parties such as construction workers. This has been achieved by network operators working more closely with third parties. The introduction of the Energy Legislation Amendment (Infrastructure Protection) Act 2009 should continue this trend.708
Table 10.17: Quantity of gas entering, and leaving NSW networks and unaccounted-for gas709
2003/04 2004/05 2005/06 2006/07 2007/08 2008/09 Gas entering distribution
system (PJ)
104.8 104.7 106.3 108.0 111.5
Gas delivered (PJ)710 102.4 102.0 103.6 105.7 109.5
Unaccounted-for gas (%) 2.27 2.53 2.60 2.11 1.83
Figure 10.12: Unaccounted-for network around Australia 711
Performance indicators on distribution network integrity and safety is stated in Table 10.18.
Table 10.18: Network integrity and safety for NSW distribution networks712
Reporting Period Third Party reported leaks per 10km Third Party reported leaks per 1000 consumers Percentage of network leak surveyed Leaks found from survey per 10km Mechanical damage per 10km Mechanical damage per 1000 consumers Emergency exercises 2004/05 4.04 10.49 24.92 3.75 0.99 2.58 8 2005/06 4.86 12.31 31.95 8.49 0.92 2.34 12 2006/07 6.11 15.38 22.10 16.01 0.95 2.39 14 2007/08 4.77 11.94 19.88 7.35 0.87 2.18 19 2008/09 5.20 12.38 23.02 8.20 0.81 1.92 22
The Energy Branch of Industry and Investment NSW produces a yearly performance report on the performance of natural gas distribution networks in NSW. In the 2009 report, it stated that the operators of the natural gas distribution networks have demonstrated a high level of performance in the network integrity, reliability, and safety aspects of operation. It noted that the averages for the Key Performance Indicators (KPI) indicate that all assets are being maintained to a very high standard.713
10.3.3 Environmental sustainability
Natural gas as an energy source has significant environmental benefits compared with electricity generated from coal. For example, coal used in producing electricity generates 80% more carbon dioxide emissions than natural gas. Jemena Gas Networks (NSW) is actively promoting the environmental benefits of natural gas, referring to it as the most environmentally-friendly fossil fuel. Key to its marketing is supporting the Natural gas: the natural choice campaign. This campaign is designed to increase the awareness of gas as an environmentally-friendly energy source, together with targeted incentives paid directly to appliance installers to encourage the uptake of gas
appliances where upfront costs present a barrier to the purchase of gas appliances.
Gas companies have also sought to minimise the risks of their operations, and in particular to reduce their environmental risk. Examples of this include:
Minimising ground disturbance by using common trenching with other utilities, and directional
boring to prevent damage to the root systems of trees
Using long-life materials to minimise the need for future maintenance activities
Minimising line purging operations and if necessary, using flaring to minimise the environmental
impact.
10.4 Future challenges
The challenges to achieving improvements in gas infrastructure are:
Planning gas infrastructure to meet demand. Given the uncertainty over the demand of
natural gas arising from the introduction of a carbon tax, other policy settings such as the Mandatory Renewable Energy Target (MRET) and the internationalisation of the domestic natural gas price, it is very difficult for infrastructure owners to be confident in their decisions about investment.
Expanding the distribution network. The growth of the network has slowed. Expanding the
network through servicing urban infill and unserved areas is expensive. Growing the network may require additional incentives for network operators that recognise the environmental benefits of natural gas.
10.5 Report Card Rating
Infrastructure Type NSW 2010 NSW 2003 National 2005 National 2001
Gas C Not rated C+ C
Based on considerations of planning, funding, and infrastructure capacity and condition, NSW’s gas infrastructure has been rated C. This rating recognises that the gas transmission and distribution systems are in a sound condition, and increases in gas exploration, production and pipeline capacity have increased supply. However, as future supply and demand for gas is highly uncertain due to government policy, the internationalisation of domestic gas prices, and the construction of new gas-fired generation plants along the east coast of Australian, it is impossible to determine if the infrastructure is appropriate for future demand.
Positives that have contributed to the rating are:
Existing high quality transmission pipelines
Good network integrity, reliability and safety of distribution networks
Ongoing replacement of aged pipelines
Increased exploration and development of coal seam gas reserves
Expansion in capacity of the Moomba–Sydney Pipeline, Eastern Gas Pipeline and NSW– Victoria Interconnect
Increased capital expenditure on the NSW Gas Network.
Negatives that have contributed to the rating are:
Uncertainty over future gas demand
Very slow growth in domestic natural gas penetration Short-term transmission pipeline capacity concerns.