AGL Energy chairman Patricia McKenzie said the faster closure of coal power plants as demanded by the company’s biggest shareholder Mike Cannon-Brookes is just not possible because replacement capacity cannot be built in time to keep the lights on and prevent prices shooting higher.

Writing in The Australian Financial Review on Thursday, Ms McKenzie said that aligning AGL with a 1.5 degree warming pathway would require the closure of all the company’s coal power generations by at least mid-2029 and for all coal plants in the National Electricity Market to shut by two years later.