The Texas electric power crisis that occurred in February 2021 has drawn great attention internationally due to its severity and for not having been foreseen. In this rapid communication

we classify the 2021 Texas electric power crisis as an energy insufficiency-caused power crisis

which alerts of a new blackout mechanism. Different from capacity insufficiency-caused power crises in the past

the Texas electric power crisis of 2021 directly resulted from the long-duration extreme cold weather as well as fundamentally from the insufficiency of sustainable supply capability of energy. We begin this paper with a brief retrospect of the event and its consequences. Definitions of energy/capacity insufficiency-caused power crises are given

as well as an overview of the supply and demand during the event

based on realistic operation data. Quantitative simulations are then conducted to reveal the underlying reasons for the power crisis and reveal how to better prepare for the future. Finally

several insights and suggestions on handling the new mode of blackout in the future are proposed and discussed.