Allows them to reduce initial construction and commissioning...

Allows them to reduce initial construction and commissioning time to start producing spod and continue producing spod while the stage 2 is being constructed and commissioned. They would have done the numbers for NPV and found this generates better value than completing the job all in one go.

Less initial construction also has the added benefit of not requiring as much labour and also reduces the impact of commissioning issues occurring as there is less equipment to check and test before starting to produce.