The fate of a major low-carbon technology is playing out in the states, where regulators are contemplating whether it's worth paying for -- and whether federal law will change that. Integrated gasification combined cycle, or IGCC, is held up as one of the main ways to reduce greenhouse gas emissions from coal. It essentially extracts carbon dioxide from coal and concentrates it before the remaining gas is burned to generate power. The CO2 can then be dispatched for storage underground. The process can capture 90 percent of the CO2, and the "combined cycle" aspect raises the efficiency of burning coal. Yet like many low-carbon technologies, IGCC is unproven at scale. Capital costs can top a few billion dollars, so investors are reluctant to build an IGCC plant fully on their own dime.