The federal stimulus devoted $2.4 billion to pilot projects aimed at capturing carbon dioxide emissions and making coal-fired power plants "cleaner." Such plants account for a third of U.S. greenhouse gas emissions. "Yet carbon capture and storage remains the elusive holy grail of the coal industry, an idea that could contain the damage inflicted by coal-burning power plants but a technology that remains expensive, energy intensive and largely untested," a Washington Post article noted. "Even optimists say it will not be commercially available for another six to 10 years. Pessimists say it might take much longer, and may never be ready for widespread use without attaching a punishingly high price to carbon."