A renewed attempt to develop ways of making power stations greener is set to be unveiled by the government. For the second time in five years, £1bn will be offered for schemes to trap and bury carbon dioxide. An earlier competition collapsed after all nine entrants pulled out, most citing cost as the main problem. The last to withdraw was a project run by Scottish Power at its Longannet station in Fife, and the prize money was not awarded Known as \"carbon capture and storage\" (CCS), the idea is to prevent CO2 escaping into the atmosphere. A major part of the government\'s low-carbon strategy, CCS has been plagued by delays and uncertainty. Its attraction is that existing fossil fuels including coal and gas can be burned without releasing the usual quantities of CO2, the key greenhouse gas. Instead of being vented into the air, the gas would be trapped and then piped into long-term storage in old oil fields under the North Sea. The original hope was for British firms to design systems that could be fitted to the soaring numbers of coal plants in China and India to reduce their emissions. However the research has proved costlier and more complicated than many expected, and the timescale keeps slipping. Revised rules Only last month the National Audit Office criticised the government for taking \"too long to get to grips\" with the commercial and technical risks involved. Now ministers are hoping that by revising the rules for the competition they will have a better chance of attracting more interest. In the last contest, entries were originally limited to designs that could only be used at power stations burning coal, not gas. And the rules also only allowed systems that trapped carbon dioxide after the fuel was burned - so-called \"post-combustion\". By contrast, the new competition will be open to coal and gas stations, and to schemes that attempt to capture carbon before combustion. As one official put it to me: \"Lessons have been learned and we\'re not closing our eyes to what industry is suggesting.\" A three-month consultation opens with selected projects expected to be running by 2016-2020. But, as with the last competition, a key factor will be viability. Although many of the technologies have been proven at a small scale, no industrial-scale project has yet been tested. A further concern is price. With the precise designs still to be settled, estimates for future running costs are uncertain, including the price of emitting carbon and the size of low-carbon subsidy. The announcement comes amid uncertainty about the government\'s energy policy, after RWE and e.ON pulled out of a major project for new nuclear power stations last week. The policy has four key strands: new nuclear stations, a huge expansion of renewables like wind, efficiency measures to cut energy use and reducing emissions from coal and gas by using carbon capture and storage. So the new announcement will mark another important effort to revive a potentially crucial technology that has faltered so far. From: BBC