The first phrase is correct.
Most glass furnaces are fired by gas: some have electric boost. The few all electric furnaces are the most expensive to run.
I know. You are clueless and just babbling.
And gas fired furnaces have been around for how many decades (or more). I find it disturbing that you compare a mature, well understood and well developed technology with an untested, unproven, unregulated, unexamined, not understood and not certified technology. I don't think you understand major corporations as well as you claim.