In Hot Water

Geothermal signs

Jan and Gerry are in Taupo, one of the geothermal wonderlands of the world.  Taupo sits in the Taupo caldera, one of eight large, nested erupted centers in the central part of the North Island.  Hot water pools, steam vents, and geysers are scattered throughout the region, and some of the underground heat is tapped to produce electricity from steam wells.  The local development, Wairakei, is one of the first and one of the largest geothermal sites in the world producing geothermal electricity.

Wairakei Geothermal Field

I have read about Wairakei for many years, and it is one of the holy grails for renewable Earth energy.  So you can imagine what we spent most of our time doing yesterday—looking at pipes, plants, power lines, steam, and hot water.  Can it get more exciting than that?

The Taupo caldera erupted 27,000 years ago and ejected 1100 times as much material as the 1980 eruption of Mt. St. Helens.  Taupo also erupted about 180 years ago; that one was a measly 100 times bigger than Mt. St. Helens.  These are big events!  Some of the heat of these eruptions is still in the ground.  We hope another eruption will not occur in the next 2 or 3 days (while we are here); for one thing, the next big eruption should have lots of warning signs—like earthquake swarms.  Thinking about an eruption in a populated area like this is much like imagining California waiting for the Big One — it’s just a matter of time.  Since big eruptions have recurrence intervals of 100s to 10,000s of years or maybe more, maybe the risk isn’t too high between now and Wednesday.

The warm waste water from the geothermal power plant is used to grow prawns (giant shrimp) in a series of ponds.  The warm water makes them grow faster than normal.  For $20 you can fish for them with rod and reel and keep what you catch.  We haven’t done this, but how much fight can a prawn have?  Do you mount the biggest and put it on the wall?  This must be a bizarre fishing experience.

Another bizarre, but enjoyable, experience is viewing the Aratiatia Rapids.

Aratiatia Rapids -- before and after water release

These rapids went dry when a dam diverted all the water to a hydro-power plant.  Due to public outcry, the water gates to the rapids are now opened four times a day at precise times (10, 12, 2, and 4) preceded by sirens.  There is even a countdown clock.  Then, whoosh, the rapids are fully flooded and foaming for 30 minutes before the water is shut off again.  Where else can you see dry rivers become foaming rivers in a matter of minutes?  The little duck we watched in the river seemed to know just how to get out of the way of the coming water surge.