Certainly barriers such as having the land, environmental...

Certainly barriers such as having the land, environmental approvals, grid connections, and community support are all reduced or nullified when replacing old turbines. A change in height might trigger some additional environmental impact assessments, but certainly not as troublesome as for a new site. Capital wind farm is coming up to 12 years old. A 25 year operating lifespan would mean replacement in 2033 - just as Origin closing Eraring power station - perfect timing!