It would be very important if Bitcoin miners would find a way to lower their electricity costs.
When you say costs, you are thinking of consumption. Like any technology that evolves and improves, future ASIC miners will provide more hash power with lower energy requirements. That's how you decrease total consumption.
If we look at the Chinese mining industry, where most Bitcoin mines operate...
Not anymore. That's a thing of the past. Mining bitcoin is no longer allowed by the Chinese government. Big players have reallocated to the US, Russia, Kazakhstan, and other nations that can provide affordable electricity.
It looks like this is one of the attempts and a hot issue in the future to make it look much greener to Bitcoin miners now that renewable energy is becoming more affordable.
Bitcoin is already using plenty of clean and renewable energy in areas where that is possible. If not, like any other industry, mining companies will use what is available and what is cheap.