Texte - A breath of fresh air

Now Klaus Ohlrogge and his colleagues at the government-funded GKSS Research Centre in Germany have devised a novel way of cutting vapour leakage to less than 5 per cent. The system works by sucking out 1.5 times as much air as the volume of fuel being pumped into the car tank, and pumping this air into the headspace of the filling station's storage tank.
When the pressure in this tank is higher than the pressure outside, this vapour-laden air is funnelled through a stack of membranes coated with a silicone material that selectively adsorbs hydrocarbons based on their chemical structure. The adsorbed hydrocarbons diffuse through the membrane coating into a porous inner layer, pulled by a concentration gradient, from where they are funnelled back into the station's storage tank. The cleaned air is then vented to the atmosphere.
Nine petrol stations in Germany are trying out the system, and one unit is being tested in the US.

Nicola Jones

RETOUR

THE stench of petrol at filling stations could soon be a thing of the past, the ACS heard.
For every litre of petrol that goes into your tank, about a gram of vapour is released into the air. The hydrocarbons in petrol contribute to ozone and smog, and its aromatic compounds are suspected carcinogens and in high doses can cause leukaemia. An additive called methyl-tert-butyl ether (MTBE) adds a pungent smell to the fumes.
"There have been reports of feeling

unwell after exposure to MTBE, and it has caused tumours in animal experiments." says Melinda Henry at the World Health Organization in Geneva. The WHO doesn't recommend limits for petrol vapour emissions, but to meet local regulations some filling stations in the US and Germany have fitted vacuum pumps that suck excess vapour and air back into the filling station's tank. However, even the best of these systems still allow a quarter of the vapour to escape.


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Breath of fresh air No more nasty vapours when you top up your tank at petrol stations		Now Klaus Ohlrogge and his colleagues at the government-funded GKSS Research Centre in Germany have devised a novel way of cutting vapour leakage to less than 5 per cent. The system works by sucking out 1.5 times as much air as the volume of fuel being pumped into the car tank, and pumping this air into the headspace of the filling station's storage tank. When the pressure in this tank is higher than the pressure outside, this vapour-laden air is funnelled through a stack of membranes coated with a silicone material that selectively adsorbs hydrocarbons based on their chemical structure. The adsorbed hydrocarbons diffuse through the membrane coating into a porous inner layer, pulled by a concentration gradient, from where they are funnelled back into the station's storage tank. The cleaned air is then vented to the atmosphere. Nine petrol stations in Germany are trying out the system, and one unit is being tested in the US. Nicola Jones © New Scientist 2002 RETOUR
THE stench of petrol at filling stations could soon be a thing of the past, the ACS heard. For every litre of petrol that goes into your tank, about a gram of vapour is released into the air. The hydrocarbons in petrol contribute to ozone and smog, and its aromatic compounds are suspected carcinogens and in high doses can cause leukaemia. An additive called methyl-tert-butyl ether (MTBE) adds a pungent smell to the fumes. "There have been reports of feeling	unwell after exposure to MTBE, and it has caused tumours in animal experiments." says Melinda Henry at the World Health Organization in Geneva. The WHO doesn't recommend limits for petrol vapour emissions, but to meet local regulations some filling stations in the US and Germany have fitted vacuum pumps that suck excess vapour and air back into the filling station's tank. However, even the best of these systems still allow a quarter of the vapour to escape.