By Melissa Reynolds

Imagine a form of electricity that emits zero carbon dioxide emissions to the atmosphere, at a relatively low cost. Sound like a far-off dream? Think again.

A new type of natural gas electric power plant proposed by MIT researchers could do just that, all at costs that are comparable to, or less than, conventional natural gas plants or coal-burning plants. The findings were made by MIT postdoctoral associate Thomas Adams and Paul I. Barton, a Lammot du Pont professor of Chemical Engineering.

The system the scientists have designed uses solid-oxide fuel cells to produce power from fuel without burning it. This system has the advantage of running on natural gas, which is a fuel source that is plentiful. (Proven global reserves of natural gas are expected to last approximately 60 years at current consumption rates.)

Such findings, though, will only be commercially viable when and if a price is set on the emission of greenhouse gases.

This system couldn't come at a better time. Currently, natural-gas power plants produce an average of 1,135 pounds of carbon dioxide for every megawatt-hour of electricity that is produced, and natural gas accounts for 22% of electricity production.

The system of solid-oxide fuel cells would cut out harmful gas emissions, only releasing pure carbon dioxide into the air. The process of carbon capture and sequestration (CCS) would store the carbon dioxide underground. The cell system would also produce clean water that could be used for other purposes.

CCS involves separating out the carbon dioxide from other gases and injecting those gases into deep geological formations to keep them from heading out into the atmosphere.

While the cheapest fuel will always be pulverized coal, the system designed by Adams and Barton comes close. Computer simulations were used to analyze the relative costs and performance of their system versus others.

A very low level of carbon tax, about $5 to $10 per ton, would make this technology cheaper than coal plants. Combined-cycle natural gas plants, which are the most efficient type of fossil-fuel power plants, could be set up with a carbon capture system and reduce the output of greenhouse gases by more than 90% at a comparable cost and with a higher efficiency. Once there is a form of carbon pricing, the true price exacted on the environment by greenhouse gas emissions will be known.

The system has been demonstrated in small-scale units, although not in a full-scale plant yet, and prototype megawatt-scale plants are planned for 2012. Once the system has been proved at any size, it can be increased to fill the need.