The answer to the renewable energy industry's biggest challenge is emerging in the Australian Outback.

Early next year, one of the first power projects that combine solar and wind generation with battery storage is planning to start up in northern Queensland. The Kennedy Energy Park, just outside the sleepy town of Hughendon, will combine 43 megawatts of wind and 20 megawatts of solar with a 2-megawatt Tesla Inc. lithium-ion battery.

Hybrid projects like this aim to tackle a problem faced by climate-change challengers and grid planners across the globe: how to firm up intermittent renewable power so that the lights stay on when the sun doesn't shine or the wind doesn't blow.