SEEN the steam from a car exhaust during cold weather just after mum or dad start the parental taxi in the morning? That’s water vapour condensing.
Within a few minutes of start-up, that steam disappears as the exhaust gets very hot. You can easily burn yourself. That’s because of the waste heat pumped out by the car’s engine.
What if it were possible to somehow collect that energy disappearing down the tailpipe? A team at Cardiff University is trying to achieve exactly that. It’s about “greener” power.
Professor Mike Rowe’s idea is to use thermoelectric generation to achieve this by employing devices known as thermocouples to convert heat into electricity.
A thermocouple is a sensor for measuring temperature. It consists of two dissimilar metals joined together at one end. When the junction of the two metals is heated or cooled, a voltage is produced that can be correlated back to the temperature.
The conversion technology is used in everyday applications such as controlling the central-heating system or refrigerator temperature.
Now, Prof Rowe aims to use this technology to generate electricity from the waste heat in vehicles.
He says: “The main interest in cars is to decrease the petrol consumption and reduce carbon-dioxide (CO) emissions. If you can utilise the exhaust heat you could replace the alternator. This would provide a 5% saving in fuel straightaway.
“Thermoelectric generation is a green solution. It can, in many instances, cost less than solar energy. It has huge future potential yet it has been neglected to date in the UK.”
This kind of work has been going on for several years in the US.
And besides, heat recovery is commonplace in power stations, where huge quantities of energy would otherwise be lost up exhaust stacks; and in ships, where significant savings on fuel bills are well proven.
So the idea of a compact heat recovery system on the family car should be a no-brainer, wouldn’t you think?