Geo-scientists say it is possible to measure greenhouse gas emissions from power plants by checking the grass outside.

The new method developed in New Zealand uses a novel sampling technique of collecting grass growing downwind of power plants, and can faithfully record measurements of the carbon dioxide emitted from the plant.

Its inventors say the technique allows independent verification of greenhouse gas emission rates, something that previously could only be self-reported by power companies that use fossil fuel plants.

“Our new technique provides an inexpensive and simple way to verify that companies and nations are actually doing what they have promised to do,” says Dr Jocelyn Turnbull, lead author of research published this week in a Proceedings of the National Academy of Sciences paper titled ‘Independent evaluation of point source fossil fuel CO2 emissions to better than 10%’.

Due to the extreme age of fossil fuels, carbon dioxide released from combustion contains zero radiocarbon, whereas natural carbon dioxide sources contain high levels of radiocarbon.

By measuring the amount of radiocarbon present, the researchers are able to determine how much of the carbon dioxide at the location of each grass sample was emitted from the power plant.

They use wind data to translate the measured fossil fuel carbon dioxide concentrations at each location to the rate of emissions from the power plant.

The researchers said it reduces uncertainties in the emission rate to less than 10 per cent - an improvement over the current 20 per cent using other more conventional methods - and was enough to allow governments to verify the reported emissions.