What makes you think that if the Heritage Foundation's carbon trading scheme can't get passed, a tax will?
An carbon trading scheme advantages some companies at the expense of others depending on what benchmark is used, and the total emissions cap for the nation is centrally determined rather than flexible enough to respond if demand outweighs the increased price from the tax. After the financial crisis, the idea of creating another complex trading scheme doesn't look so good.
I think a carbon tax is probably the way to go for environmental reasons, but with energy prices as high as they are now it makes sense for them to be offset to be revenue neutral.
