A blog I only recently discovered and already much admire, The Hive has an excellent post on realistic commercial solutions for New Zealand energy needs. It is a position I have long believed in. Use sustainable sources to generate and store hydrogen and then use that stored energy when you need it. This gets around the fundamental problem that sustainable energy sources generally have, which is that the time of generation is not the same as the time or requirement and traditional storage methods are not commercially viable.
New Zealand for example has a wonderful opportunity to lead the way in hydrogen solutions. We have a relative abundance of energy (both power from renewable sources such as wind and hydro and huge coal reserves – 1,000 years worth of coal reserves) and we have lots of water. If the wind is blowing and we have a heavy snow melt or lots of rain, New Zealand has more energy than it can use. The spot price for electricity drops to close to zero. Why not turn it into hydrogen? All you need electricity and water. The hydrogen could be used to power cars, trucks and busses, and even buildings or groups of buildings. New Zealand’s greenhouse gas contribution could reduce substantially.
For instance the Waitaki Hydro scheme had total average energy output of 6,744 GWh. Its station generation output is 1526.2 MW. The scheme is operating at around 50% of its theoretical capacity of 13,369 GWh is all stations were run 24 hours a day all year.
Obviously drought and maintenance would substantially reduce the difference but there is still an enormous opportunity to capture the energy value of all that water going over the spillway rather than through the turbines.