Some day gas and crude oil will be a thing of the past. With innovations here and there. In your own opinion what will replace gas and crude oil in the international market.
These natura resources won't last forever most especially gas and crude oil. There are lots of resources that are being discovered up till date, some are being shared with the world and there are others that are kept as a secret. Few months ago a rock was discovered somewhere in Nigeria and it was said to have the capacity to power a full state and also has a lot of things that it can be used to build but with the corrupt leaders the country has this resource would be sold out to foreign countries instead of using it to make their own country developed
Gas and crude oil won't last forever but it's good enough to get us going while we still aren't capable of harnessing renewable energy very efficiently.
Once we have developed better technology, gas and crude oil will have lower economic value. Until then we will still use it.
I'm sure that the future of energy is nuclear power plant but solar energy can also be a good alternative. We're literally just waiting for solar panel that can generate more efficiently right now.