BEIJING—China’s State Grid Corp. already dominates its home market, operating most of the electricity grid that powers the world’s second-largest economy. Now it has big plans for the world: a $50 trillion global power network that harnesses Arctic winds and equatorial sunlight.

State Grid Chairman Liu Zhenya outlined his company’s vision Wednesday, saying a new global electricity network is the world’s best bet for overcoming resource scarcity, and limiting the effects of pollution and climate change. Knitted together by...