The plan has plenty of problems, not least its viability. Even the president doesn't seem to know what he wants.

For example, is the tax expected to fall on production or consumption?

Ed Crooks, the energy editor of The Financial Times, said in a tweet that the amount mentioned, a tax of $32 billion per year, would be consistent with a production tax. Given that oil companies are losing money hand over fist at current prices, reducing net revenues by $10 per barrel would have the effect of destroying the domestic oil business.