Scientists there say they have developed a way to produce truly carbon-neutral fuel and useful organic chemicals at large scale using water and carbon dioxide removed from the air as raw materials. There are plenty of schemes brewing to capture carbon dioxide, both directly from the atmosphere and from the stacks of power plants. All of them, for the moment, are costly or hard to envision at the billion-tons-a-year scale that would be needed to blunt the buildup of carbon dioxide in the atmosphere coming mainly from fuel burning.