Some thoughts: The justification for the transmission line is to allow SA to reduce their gas generation. Gas is used for system stability and when there is no sun and little wind. Adding more wind and solar will not help much in the times when gas is needed. Curtailment in SA for existing wind and solar is large and growing. The wind and solar was not well coordinated and the rooftop displaces the opportunity to develop larger renewable projects as it reduces network demand in the daytime and leaves no room for additional solar to be added.
Adding more wind and solar without storage and frequency will increase world emissions and results in additional curtailment. Storage could reduce existing curtailment however the emissions reduction has already been claimed. Also NSW plans to shut Liddell so there will be less Black coal and in time they will have the same problem. NSW solar resource is also higher than SA so makes no sense importing it,
SA have a good opportunity to slow down and fix existing problems. There is no rush and if done properly the knowledge shared will be valuable.
