Analysis of the potential value of vehicle-to-grid for fleet owners (Australia)

In this follow up post to the UK Vehicle-to-Grid simulation this time we're looking at the Australian market, in particular the National Electricity Market (NEM) on the east coast, and whether V2G makes sense for a fleet owner.

Background

Again we've used the Gridcog software to model our small fleet of rubbish trucks to explore what V2G might have been able to deliver in terms of additional financial benefit to the fleet owner over the last four years. 

Given that the NEM has regional pricing we've created identical depots in Brisbane in QLD, Sydney in NSW, Melbourne in VIC and Adelaide in SA, where the sites are exposed to the corresponding wholesale markets and network tariff price signals based on their locations.

We then have a baseline scenario with the fleet charging as normal, with charging optimised to reduce energy costs for the site operator, and then a second scenario this time with V2G enabled. 

The Model

• The project is modelled over the last four years from 2019 to 2022 inclusive.
• We have a small fleet of 8 rubbish trucks each with a battery capacity of 300kWh and a daily energy requirement of 250kWh on days the trucks are operating.
• The fleet is out at work from 5am to 3pm Monday to Friday.
• The depot has 5 x 100kW chargers.
• The depot’s grid connection allows max import and export of 500kW
• The depots are directly exposed to the historic spot price for their NEM region and also incur charges for use of the distribution network (Adelaide = SAPN LBAD non-CBD, Brisbane = Energex 8300, Melbourne = Ausnet NSP75 and Sydney = Ausgrid EA310).
• For the baseline scenario the fleet uses smart-charging only i.e. the fleet is charged at the lowest possible cost whilst still allowing normal operations.
• For the V2G scenario the vehicle batteries are never allowed to discharge below 30% state of charge.
• Capex costs are ignored, this is just focusing on potential value. In reality there will likely be additional costs associated with enabling V2G.

The Results

• All sites see significant financial benefit from V2G although no surprisingly there's a lot of variation between sites. This is driven primarily by the wholesale energy pricing experienced by the sites but also by the network tariffs each site is exposed to.
• Network tariffs can provide a strong disincentive to charge the EV fleet during certain periods due to the demand charges that many Australian networks levy. For example, the Sydney site is connected to Ausgrid's network on the EA310 tariff which charges $157 per kVA per year for demand that occurs between 2pm and 8pm on weekdays. Correspondingly the battery will need to secure a very high wholesale price to offset those charging costs.
• You can see in the quarterly cashflows below that wholesale market value (orange) varies significantly from quarter to quarter, reflecting the volatility that we've seen in the NEM in recent years, and expect to continue to see for some time yet.

• From an energy and battery workload perspective, total energy moved through the fleets increased under V2G but varied significantly between locations with Brisbane seeing the greatest increase in battery throughput of 64% (from 2,245MWh in the baseline to 3,689MWh with V2G)and Adelaide the lowest at 31%.
• You can see this illustrated in the interval data below for a week in April 2019 and is particularly apparent over the weekend when the trucks are otherwise parked up
  

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