Fears about power shortages appear to have prompted the latest agreement between the major power companies

Mercury, Meridian and Contact will work with Genesis Energy to look into options, to keep its Huntly Power Station operating longer than previously planned.

Transpower has warned of more shortages this winter, similar to those experienced last year.

JMI Wealth Director Andrew Kelleher says the power station is important for securing supply when the system's under stress.

He says that includes periods of low rainfall or low wind, or the morning and afternoon winter peaks.