Pumping liquid carbon dioxide underground on a massive scale so it won't contribute to global warming has been talked about for years. ­Howard Herzog, an MIT chemical engineer and the program manager of the Carbon Sequestration Initiative, an industrial consortium, says the most recent international conference on the subject--in Trondheim, Norway, earlier this year--made clear two things: First, the geological questions are being resolved favorably. Second, without policies that put a price on CO₂, it's unlikely that any sequestration facilities will actually get built.

TR: How has interest in this field grown?