Average wholesale electricity prices in New Zealand took a plunge during August as consumers heeded the call to curb their energy usage by “ten per cent for ten weeks”, according to statistics published on the special save-electricity.co.nz website.

Demand for electricity in August was around 8.6 per cent lower than in July and around 4.3 per cent lower than the same time last year. The average price at Otahuhu, the reference point for the upper North Island, dropped to 9.93 c/kWh from 14.90 c/kWh in July.

The lower North Island reference point at Haywards recorded a significant price decrease to 11.13 c/kWh, down from July’s figure of 23.68 c/kWh. The average monthly price at Benmore, the South Island reference point, recorded a similar fall to 12.73 c/kWh, down from 23.82 c/kWh in July.

Transmission constraints in the Taranaki region were eased at the beginning of August, allowing more electricity to be transported south.

Southward transfers are unusual, as it is far more common for the South Island to supply power to the North. To put this in perspective, southward flows in August 2001 totalled 189 GWh, more than six times the 30 GWh transferred during the whole of 2000.

These southward flows also contributed to the falling wholesale prices as less pressure was placed on South Island hydro generation plant to use highly valued water to generate. Storage in the southern hydro lakes remained relatively stable during the month, thanks to the programme of measures designed to ensure security of supply in the current situation.

These measures included the ten per cent for ten weeks campaign designed to decrease demand and the increase in transmission capacity of the national grid. Consumers have yet to reach the ten per cent target with savings running at about 6.5 per cent on average. In recent days however, consumption has approached a ten per cent reduction on previous years.

At the end of August the country was still waiting on the usual spring inflows. National storage was at 1,387 GWh, 67 per cent of the average for that time of year, with South Island storage at 73 per cent of average. Lakes Tekapo and Pukaki, which account for almost 55 per cent of New Zealand’s total storage capacity for hydroelectric generation, recorded storage levels of 27 per cent and 36 per cent respectively.

Lake Taupo was 20 per cent full. Daily updates on price, demand and hydrology since the beginning of the ten per cent for ten weeks campaign have been posted on the www.save-electricity.co.nz website.