A toxic gas used to make flat-screen televisions and laptop computers could have a bigger greenhouse impact than the world's largest coal-fired power plants, according to new scientific research.

Nitrogen trifluoride, a chemical cleaning agent used in flat screen production, is estimated to be 17,000 times more potent than carbon dioxide as a greenhouse gas.

A new research paper by Professor Michael Prather, a lead author of five reports by the Intergovernmental Panel on Climate Change, says once Nitrogen trifluoride is released into the atmosphere, it persists for around 550 years, and ''will take centuries to clean out.'' The paper, published online in Geophysical Research Letters, claims if 4000 tonnes of nitrogen trifluoride the amount to be manufactured this year was released into the atmosphere, it would have a warming effect equivalent to 67 million tonnes of carbon dioxide.

Professor Prather said this exceeded ''even that of the world's largest coal-fired power plants'', in the United States and China. Their greenhouse emissions are estimated at between 25 and 32 million tonnes.

Global demand for the gas is set to double within two years, but there are no studies measuring its levels in the Earth's atmosphere.

Professor Prather said claims that only 2 per cent of the gas potentially escaped to the atmosphere during its use, transport or disposal, conflicted with recent studies which showed ''a maximum destruction efficiency of less than 97 per cent''.

Although part of a $US52 billion ($A54billion) global ''electronic gases'' market, nitrogen trifluoride isn't listed under the Kyoto Protocol because it was only manufactured in small amounts for niche markets when the treaty was agreed in 1997.

''Nitrogen trifluoride can be called the missing greenhouse gas. It is a synthetic chemical produced in industrial quantities, it is not included in the Kyoto basket of greenhouse gases, or in national reporting under the United Nations Framework Convention on Climate Change,'' Professor Prather said.

The gas was developed as an experimental rocket fuel in the 1960s, then used in chemical lasers for the United States Star Wars missile-defence system. Its current role in the booming world make flat-screen televisions has made it a US export industry worth $A1.35 billion last year to Air Products a gas plant in Pennsylvania's coal region with demand projected to double by 2010.

Several new factories are being built in the US, South Korea and China to meet global demand for the gas, with prices expected to rise well above $A20.80 a kilo compared to around $A2 for other commodity gases.

Professor Prather warned a boom in global demand for flat-screen televisions and other flat-panel display products could lead to '' a trade off'' between more efficient use of the gas and ''faster throughput'' of manufacturing encouraging greater emissions.

''Experience with ozone-depleting gas has shown emission inventories from the chemical industry cannot be relied on,'' he said.

A leading CSIRO atmospheric scientist, Dr Paul Fraser said nitrogen trifluoride was one of a number of ''chemicals on concern'' not currently listed under the Kyoto Protocol.

''We don't have a large electronics industry here, so while the use of nitrogen trifluoride might not be an Australian problem, its global warming potential is certainly is a global problem.''