Ethanol is not make from ethane.
Actually, it can be. Have to convert to ethylene first, of course, then make ethanol from that. I think that route is actually cheaper than the corn derived EtOH one, but the EtOH made by from natural gas is not considered "renewable".
It's been some years since I looked at the economics of the two, and it things have undoubtedly changed, so the NatGas to EtOH may no longer be less expensive today.