The Gift of High Water

Even a gift freely given sometimes comes at a cost.  So it is with hydro-power, New Zealand’s pre-eminent renewable energy generation.  The country is blessed with water-bearing westerly winds, high ground to catch some of the water and short steep distances to sea level allowing gravitational energy to be converted to oh-so-convenient electricity.  Hardly anyone now laments Hora Hora Power Station, built in 1910-13 and drowned under Lake Karapiro in 1947, as they enjoy the fruits of the contribution Karapiro power station makes to the national grid and enjoy the lake itself, as a landscape feature and rowing venue.  Many people over the age of about 50 remember well the controversy surrounding raising Lake Manapouri that raged through the 1960s.  The best way of matching demand for electricity to supply is reducing demand!  Profligate use and avoidable losses need to be eliminated.  Where new electricity generation is justified, hydro-power is still a good, renewable option.  The downsides, including flooded land and ecosystem effects in rivers upstream and downstream of a dam, lead to a need for careful balancing.  I addressed this balance in part in a presentation to U3A in 2004.  Now the balancing act is requiring attention for hydro projects on the West Coast of South Island, and in Canterbury and Hawkes Bay in relation to water storage for irrigation.  The Opuha Dam in Canterbury provides an example where there has been, arguably, a hydro-electric, irrigation and fishing win, win, win.
Source [Opuha Dam]: http://ecan.govt.nz/publications/General/LivingHereNov08.pdf