Researchers want to store renewable energy as methane.
This would be another way instead of using batteries as energy storage device. And for the production of the batteries you need a lot of seldomly available resources.
![renewable energy as methane](https://i0.wp.com/192.168.178.127/wp-content/uploads/2019/04/gas-1749026_1280-1024x767.jpg?resize=580%2C434)
https://www.engadget.com/2019/04/05/stanford-renewable-energy-storage-microbes/