> contention for resources starts triggering wars
There is no economic or historical basis for this. When resources become more scare people begin looking into alternatives or alternate extraction methods.
This is how the iron age came to be. Iron was common to many local areas, but the tin to make bronze had to be imported from far away. It took innovation to develop the necessary techniques for iron smelting which turned out to be a superior material for tools in addition to being extremely common and readily available.
They use to think this way about crude oil. That we would eventually run out or that everybody needs to go to war to protect their strategic assets in the middle east. This turned out to be complete non-sense. Techniques that revolutionized natural gas extraction were adapted to oil extraction following massive oil price fluctuations. Now Texas out produces Saudi Arabia. Europe now produces large amounts of petroleum from Norway.
They used to also think this way about lumber and rubber, both of which are renewable resources. Now the world produces plenty of both with minimal environmental disruption.
The US has plenty of coal and coal is relatively cheap to extract and ship, but there will always be a minimal fixed price to coal-based energy. Renewable energy scales more efficiently and now is cheaper than coal due to wholesale energy production, especially in Texas which now also dominates renewable energy production.
When there is sufficient demand people will find a way well before going to war. War is very expensive.