I had that problem to some extent in the earlier stages of the game. A charcoal kiln helps, since the supply of wood is effectively infinite (my farm is constantly overgrown with trees). And once you do Robin's Special Order for 1000 wood, well, by definition you've got a ridiculous amount of wood to use up.
Hitting the mine for Dust Sprites will also help. I really should do that more often, since they're one of the more useful Monster Eradication goals.
Skull Caverns seems to give a better ratio of coal to ores, but I don't have a large sample size to be sure of that.
But yeah, the coal cost for preserves jars and beehives is limiting. I only have four and two, respectively, while the keg count is 50+ and increasing as fast as the oak resin comes in (need to make more Tappers...). Your example of 100 ore to 40 coal is not bad, actually, you have enough to smelt it all with 20 coal to spare for other ores, a couple of preserves jars, or whatever.
Re: Ereo's suggestion of the Prospector profession probably won't help, from what I've seen. By the time you hit Mining 10 coal probably won't be a big deal anymore (I'm at 9, and considering how long going from 8 to 9 took I don't expect to see 10 for ages). I went with Geologist for level 5, and will probably take Excavator at 10.