why is geothermal energy so important?, page-4

Yes.

Most of their schemes use existing underground water in a simple single use system which is then released to the environment e.g. rivers. This has lowered the available flow rates and pressures as the recharge of the aquifer is slower that the rate of extraction. Whether reinjection of water to the hot hocks is possible is beind investigated.

Waireki,the oldest scheme, has had it's steam pressures and volumes more than halved in the 40 yrs of operation
In the latest projects they are trying to use a closed water loop similar to that GDY is planning.

The total volume of hot rock available for Geothermal heat in NZ is few tens of cubic Kilometres compared to several thousand++ cubic Kilometres in the GDY leases. This smaller rock volume is typical of shallow plate boundary situations.
Only continental schemes have the massive volumes needed for very large schemes.

California has had even more dramatic declines for the same reasons.

This is one of the main reasons that GDY has not chosen to directly use the very high geothermal pressures and volumes from H#1 in an open single use system rather that the closed cycle being persued. That choice is one factor in the metallurgical problems encountered in the H#3 episode.

RB