A method of producing a fuel additive includes passing a feed stream comprising C4 hydrocarbons through a butadiene extraction unit producing a first process stream; passing the first process stream through a methyl tertiary butyl ether unit producing a second process stream and a methyl tertiary butyl ether product; passing the second process stream through a hydration unit producing the fuel additive and a recycle stream; passing the recycle stream through a hydrogenation unit; and recycling the recycle stream to a steam cracker unit and/or to the feed stream