But I have a GAS fireplace! The original owner of my house was the president of the local gas company so everything (including the air conditioner) is natural gas. My latest bill was up 50% from the previous period.
And yes, it's cold here in Michigan!
When you remove the gas lit fire, install an alternative. There are really great wood pellet burners that look great when they are burning. Wood pellets are cheaper than gas. OTOH, just use good old logs. I love to burn logs and love to chop logs for a really great fire. Have fun!