Brisbane’s coldest July day for 30 years, a plant outage and cloudy weather that cut generation from solar panels have combined to once again drive extreme spikes in wholesale prices in Queensland that could lead to the renewed suspension of the National Electricity Market.

The Australian Energy Market Operator was forced to urgently call for emergency generation supplies on Tuesday afternoon as it worked to keep the lights on for a four-hour period later in the evening, as reserves fell short amid ongoing outages at coal power plants.