We can use the Resource Exchange feature available in Alliance tab [Alliance>Territory] at 45 days of server age.
This feature helps to exchange an alliance resource with different type of alliance resource.
The resource exchange ratio is different considering which resource you are exchanging with and for.
We can only exchange 100K resources everyday.
The exchange ratio is :- Meat/Wood to Wood/Meat ➛ 2:1, Meat/Wood to Coal ➛ 4:1, Meat/Wood to Iron ➛ 8:1, Coal to Meat/Wood ➛ 1:1, Coal to Iron ➛ 4:1, Iron to Meat/Wood ➛ 1:2, Iron to Coal ➛ 1:1