It wasn't specifically announced as to why, my guess is because...

It wasn't specifically announced as to why, my guess is because the dynamics of the wholesale market have drastically changed with renewables. To be able to run the steam generator they have to run at a minimum load point (usually starting around midday or early afternoon) for enough heat to build up - the times they would be running at are consistently becoming negative price points. This will be exacerbated further as more renewables come online too. TPS will only be looking to capture the volatility events / peak prices, so no point keeping it operational. Good choice by management and it works really well given the contracts having been changed to fit this model. Now it means they can redirect gas to other opportunities and realise better net gas back $ essentially.