China Shuts Down Pearl River Delta Electricity Grid for "Wartime" Conditions

Long story short: China cut its energy supply (Australian coal imports) and then was hit by surging demand as temperatures plunged in Southern provices. Result: widespread blackouts in the heart of China's economy. Water and cellular communications were knocked out as well. Apple Daily: 廣東大停電｜廣深珠等多市無預兆停水停電斷網 醫院受影響 廣州供電局：電網故障

The authorities announced earlier that electricity consumption will enter a "wartime state", and provinces have successively limited electricity.

The "wartime conditions" are the result of a self-imposed naval blockade of Australian coal imports.

MacroBusiness: Angry China blacks itself out with Aussie trade war

China is suffering mass power cuts in the south, prompting cities to dim street lights, suspend factory production and tell office blocks to turn off heating unless the temperature falls below 3C. The electricity crisis appears to have been prompted by a shortage of coal after Beijing banned imports from Australia. China imposed trade bans against Australia after Canberra demanded an inquiry into the origins of coronavirus and criticised Beijing’s treatment of the people of Hong Kong. …China has insisted it is trying to reduce its dependence on coal. However, the combined effect of a surge in demand for electricity prompted by a colder than usual winter and the economic rebound following lockdown suggests that the country may not be able to wean itself off Australian coal so rapidly.

This is like what California is doing over 10 years, but all happening in a couple of months.