Our assumptions include:
- Each battery has a capacity of 10 kWh and a charge/discharge power of 5 kW.
- Your home battery charges from solar between 7am - 6pm during the two cheapest (and usually greenest) hours each day. This is used to calculate the min daily charging price.
- Your home battery would then export to the grid during the two most expensive hours (when wholesale energy prices are highest) between 6pm - 23:59pm each day. This is assuming all of the stored energy hasn’t been used by your home beforehand.
- Five min prices are used when calculating mean charging and discharging prices each day.
With this in mind, we multiplied the number of batteries in Australia (150,000) by 5 kW to get a total MW value for the fleet that exists today - and that which would be possible if all 3 million homes with solar got a battery and discharged at peak time.
Scenario 1 - 150k home batteries are automated:
150,000 homes x 5 kW / home = 750,000 kW = 750 MW
Scenario 2: If 3 million homes had a battery:
3 million homes x 5 kW / home = 15,000,000 kW = 15,000 MW = 15 GW
Fossil fuel energy displaced from the grid during peak time
In scenario 1, 750 MW of power is equivalent to more than 3 power plants the size of Quarantine Power station in SA (a gas peaking plant) being displaced by batteries at peak times.
In scenario 2, 15,000 MW (or 15 GW) of power is equivalent to 67 Quarantine Power Stations being displaced at peak time.
Quarantine power station has a maximum output of 224 MW.
Carbon emissions avoided during peak time
We calculated that the 750MW of power which 150,000 automated batteries could put into the grid at peak time equates to 1,500 MWh of energy displaced each day that would otherwise come from coal and gas.
In the National Electricity Market (NEM), on average 0.66 tonnes of carbon is produced for each MWh of energy generated.
Which means that by putting 1,500MWh of renewable energy into the grid during peak time each day, home battery owners would help avoid 359,255 tonnes of carbon dioxide being produced on a yearly basis.*
According to the government’s Department of Climate Change, Energy, Environment and Water, a less fuel efficient car emits around three tonnes of greenhouse gases each year.
As such, automating 150,000 batteries to discharge green energy to the grid at peak time each day would help to avoid carbon emissions equivalent to taking more than 100,000 inefficient cars off Australian roads for a year.
Note: this is the equivalent number of cars off the road based on battery discharging alone across the year. It doesn't assume any net gain/loss from the charging of the battery during greener times. It's simply taking the volume of energy from the battery and redirecting that to peak times whereby fossil fuels are being displaced.
Any questions? Shoot us an email at email@example.com.
* Gas generally plays a larger role during peaks. At an average of ~0.5-0.6t/MWh, this would bring the level of displacement down slightly.