There are all sorts of ways to get a sense of when an idea’s time has come, but I recommend looking at how many conferences are devoted to it. By that measure, carbon capture and sequestration is ready for its close-up. I just got back from a conference on this, and was struck by how little the message had changed since I began writing about it in 2003 (such as here, here and here).

The basic idea, as laid out by James Dooley of the Department of Energy’s Pacific Northwest National Lab, is this: all the talk about stabilizing emissions of carbon dioxide misses the point. What we need to do to avoid catastrophic climate change is to stabilize atmospheric concentrations of CO₂. As long as we send up more CO₂ than the oceans and other sinks can absorb, concentrations will rise and the associated climate changes will worsen.

Capturing the carbon in coal and other fossil fuels that are burned for electricity has the potential to get us partway to the goal of stabilizing the atmosphere, as Stanford’s Sally Benson said in her talk. (On Benson’s Website, scroll down to her presentation at Google on Oct. 23, 2008, for a good sense of what she spoke about this week.) Carbon capture and sequestration (CCS) can get us 20 percent of the way toward that goal, she argued, with the rest having to come from efficiency and substituting renewable energy for carbon-based sources.

One hopeful sign of the potential of CCS is that the technologies to capture CO₂ at power-plant smokestacks, to pipe it to rock formations suitable for underground storage, and to sink it deep into sedimentary basins (where sandstone whose pores can hold CO₂ alternates with layers of shale that serve as an impermeable barrier) all exist. Carbon sequestration is already being used off Norway (where the state oil company decided it was cheaper to sequester CO₂ produced in its natural-gas operations than to pay Norway’s carbon tax) and at three other sites, so we have the know-how. But it won’t be deployed in any significant way until and unless we price carbon. In other words, CCS’s time has come in terms of technology, but not in terms of public policy.