June 2013

Ammonia standards under pressure

Has the Dutch government been too harsh on farmers in the last twenty years; should they be allowed to get their slurry tank out of the barn once again? Discussions about this question reached as far as the Lower Chamber, which was partly the result of a scientific article published by Arjan Hensen with fellow researchers from Switzerland and France.

Optical techniques
'Ammonia is an aggressive substance that sticks to everything,’ explains Arjan Hensen. ‘Compared to other types of air pollution, ammonia concentrations in the air are therefore much more difficult to measure. However, ECN has gained much experience in this area and uses both chemical and optical techniques to measure ammonia gas. At the time when most of the emission standards were set only the chemical measuring method was available. With this method, air polluted with ammonia is captured in a solution and subsequently analysed in a laboratory. New optical techniques are increasingly better at measuring ammonia and also show how the ammonia content in the air develops from one second to the next. It shows us effects that cannot be detected with the more simple chemical measuring method.

Question marks
In their scientific article, the researchers compared various methods for measuring ammonia to each other. They came to the conclusion that the older measuring method registers higher emissions than the new method. This calls for further research. ‘Our research queries the accuracy of the older measuring method’, says Hensen. ‘However, before we can draw any conclusions about the standards, we first need to systematically compare the measuring methods under various conditions.’

Measuring campaign
The Lower Chamber agrees. In a letter dated 22 January, Secretary of State Dijksma promised to have this studied in more detail. Arjan Hensen and former colleague Jan Willem Erisman, currently director of the Louis Bolk Institute, are part of the review team consisting of four experts. Their report has meanwhile been supplemented by foreign experts and sent to the secretary of state. ‘Based on the findings of this report, she may decide to commission a larger measuring campaign that should yield a decisive answer about the legitimacy of the emission standards for ammonia,’ hopes Arjan Hensen. A response from the secretary of state is expected before the summer break.

Are you interested in the innovative, independent measuring methods of ECN? Measuring Expert Arjan Hensen will gladly give you more information. Give him a call at +31 (0)6 10909979.