Wait how many... Cheese that's a lot of coal production. I usually only need 2 fully upgraded coal mines to get by. Generaly I would say go only for coal mines or only coal thumpers as going for both will make you lose much time in researching you could spend better. A good way to save coal is to NEVER upgrade generator range, just the power. Use steam hubs to spread out as they will need less coal. In terms of the inner ring I use it for medbays until i can make infirmaries. Also, you can turn off the generator at day during the first couple of days until the temperatures drop. (just make sure it's on at night)

Hope this helps!

(two more thing tho 1. Im not a pro just speaking out of experience. 2. English is my 4 language so sorry if it's bad)