Modelo multifásico: Fracción de Volumen (VOF)

In recent years there have been significant developments in LNG infrastructure for truck refuelling across Australia, demonstrating a growing trend for heavy vehicles to use LNG instead of diesel or fuel.

In 2009, Wesfarmers Energy opened an LNG plant in Kwinana, Western Australia which is capable of supplying 175 tonnes per day (9.7 TJ per day or 3.5 PJ per year) for power stations and 130 heavy vehicles. (Gas Today 2009,

http://gastoday.com.au/news/wesfarmers_opens_kwinana_lng_plant/001437/)

In 2011 German gas company BOC opened its Westbury Micro-LNG plant in Tasmania to supply LNG to over 120 heavy vehicles in the region. The plant has the capacity to produce 50 tonnes of LNG per day, the equivalent of 70,000 litres of conventional diesel. BOC signed an agreement in 2010 that will deliver 100 tonnes of LNG per day (5.5TJ per day or 2 PJ per year) to heavy vehicle refuelling stations along Australia’s east coast. Under the agreement, Australian coal seam gas explorer and producer QGC will supply 30 PJ (1 PJ is equal to 20 000 tonnes of gas) of coal seam gas to BOC over 15 years from July 2011, with an option for a further 15 years. (Minister for Resources Energy and Tourism,

http://minister.ret.gov.au/MediaCentre/MediaReleases/Pages/MicroLNGPlant.aspx, http://minister. ret.gov.au/MediaCentre/MediaReleases/Pages/BOC-APADealGetsLNGintotheTransportFuelMarket. aspx )

9.3

Potential impacts on gas networks

9.3.1

AECOM’s analysis

Timing is less important for gas vehicles refuelling than for electric vehicles, because gas networks can generally balance on a daily basis rather than instantaneously. Unlike electric vehicles, there is little need to analyse timing of refuelling, namely unmanaged, time of use, managed or smart charging.

Commercial CNG or LNG vehicles will need specialised refuelling stations, which are likely to be connected either at transmission or sub-transmission level if large quantities of gas are required. Network impacts from commercial refuelling are likely to be small, for the following reasons:

• LNG facilities are likely to require high capacity connections to transmission or sub-transmission pipelines, in order to supply sufficient quantities.

• There are already clear price signals for withdrawals through high capacity connections. These signals recognise the need for gas balancing and the scope for line-pack within high capacity gas networks.

• Facilities will need to provide storage for CNG or LNG prior to distribution to refuelling stations, so should be able to manage their withdrawals to reduce network impacts and costs.

There is unlikely to be much (if any) small customer refuelling from the gas distribution network, because AECOM’s modelling shows that passenger NGVs are not attractive at current retail gas prices. However technology exists for refuelling passenger NGVs from the gas distribution network, as explained in the following article from Gas Today:

OES CNG is in the final stages of developing its compressed natural gas home refuelling stations. Gas Today profiles the technology and the development of the CNG-fuelled vehicles market. ... OES CNG has developed a new compressed natural gas (CNG) refuelling system that can be

installed outside domestic garages. CNG@HOME works by drawing gas from the domestic natural gas supply and compressing it into the vehicle’s CNG cylinder. It takes approximately three hours to fill a standard passenger car, which will give it a range of 200-250 km.

... OES CNG sees a “big future” for urban deliveries, taxis, tradesmen and private commuters. As such, the range to be brought to market includes two domestic models and two commercial units. The domestic units will have a capacity of 6 cubic metres per hour (m^3/h) - equivalent to 6.6 litres of petrol - with one unit to be a standard slow-fill unit and the other to have some internal storage capacity to provide a partial boost (rapid) fill. The light commercial units will have compression capacities of 10 and 13 m¬¬3/h respectively and will both have internal storage capacity.

Some gas distribution networks operate at low pressure, to reduce losses from leaks in older pipes. Any distribution connected equipment will therefore need to be approved by the relevant network service provider. For example, ACTEW-AGL’s Gas Connection & Supply Standard Customer Contract (http:// www.actewagl.com.au/~/media/ActewAGL/ActewAGL-Files/About-us/Natural-gas-network/Natural- gas-network-prices/Gas-connection-and-supply-contract.ashx) allows customers to draw up to 6 cubic metres per hour. OES CNG’s domestic units meet this requirement. It is possible that older gas networks might need upgrading to cater for large amounts of distribution connected refuelling of NGVs.

Low take-up of passenger NGVs should mean that potential impacts on distribution networks are likely to be low. Light commercial vehicles are likely to use commercial refuelling stations which are likely to be connected at transmission or sub-transmission level as discussed above. Potential impacts on transmission networks could be greater but presumably will be customer funded. Steps 4 and 5 of the AEMC study will test whether these impacts can be managed within current gas regulatory arrangements, or whether changes are needed.

9.3.2

Submissions and other evidence

SP AusNet’s submission agrees that network impacts are likely to be small (SP AusNet 2011, p.22): “Network Impact

Presently peak durations are of relatively short durations and hence the impact of NGV charging in residential areas is likely to only impact extended networks.

The growth in the NGV market will probably be concentrated in fleet vehicles rather than the residential market. These types of customers (eg Toll, Wesfarmers) are likely to install large charging facilities, with associated storage, requiring a reasonable capital allocation and hence any gas network augmentation requirements will need to be funded by the customer. This will ensure that residential customer tariffs are not impacted.”