Electricity consumers range from large industrial sites (the most significant is the NZAS aluminium smelter at Tiwai), down to individual households. New Zealand's annual electricity consumption ('demand') is nearly 40,000 gigawatt-hours (GWh). Almost two thirds of national demand is located in the North Island.
Demand varies from year to year, but the trend in recent years has been a decrease in electricity demand of approximately 0.2% per year, on average. If demand differs from expected, it may impact on security of supply.
During previous extended dry periods, consumers have made savings which have helped to conserve hydro storage.
Recent Electricity Demand
New Zealand Demand
The demand graph below compares national demand over the last three years.
New Zealand maximum demand normally occurs over the winter months from June until the end of August.
The overall New Zealand demand over the last three months to 19 May has been about the same as the same period in 2017, and about 2% higher than the same period in 2018.
North Island demand over the last three months to 19 May has been about 1% lower than the same period in 2017, and about 1% lower than the same period in 2018.
South Island demand over the last three months to 19 May has been about 3% higher than the same period in 2017, and about 6% higher than the same period in 2018.
The following graph compares North and South Island weekly demand for generation with the System Operator’s 2017 demand forecast. Note North and South Island demand for generation has been adjusted to account for some embedded generation, and are not directly comparable with the demand graphs above.
This demand forecast is one of the inputs to the Hydro Risk Curves (HRCs) – in periods of high demand, such as winter, the HRCs are generally higher as there is a greater demand for hydro generation. Similarly, in periods of low demand such as summer, the HRCs are generally lower as there is a reduced demand for hydro generation. Note there are a number of other inputs which affect the HRCs and they may not follow this seasonal pattern at all times.
The aggregated total for the year to date for North Island demand is about 1.4% lower than the forecast, and South Island demand is about 2.3% higher than forecast.