Will Stirling engine make a comeback?
ABOUT 30 years ago, the government of the day was telling us to buy diesel instead of petrolengined cars to improve the quality of the air we breathed.
They wanted us to believe that the choking black fumes emitted by diesels were good for us.
We now know that this advice was totally ill-conceived (Mail, April 27: 'Air Pollution is 22 times more deadly than car accidents').
What they should have done was to look at ways of cleaning up the emissions of all diesels and to ban the sale of new diesel cars.
About 50 years ago the US car giants General Motors and Ford decided independently to look into the viability of replacing the existing petrol car engines by Stirling engines as a means to improve fuel economy and reduce pollution.
The work was carried out in Europe and a few cars were converted but the engine was found to be slow to warm up from cold and it lacked the responsiveness of the internal combustion engines when accelerating. (The Stirling is an external combustion engine, so it can run on any fuel or heat source).
It was expensive too, in comparison, but they did not then have the manufacturing techniques or the range of high-temperature alloys, ceramics and plastics available today.
I wonder if it is now being considered for use in hybrid cars where it would simply drive a generator to charge up the batteries? Its lack of responsiveness would not matter, it is a 'clean' multi-fuel engine and it is almost noiseless in operation.
The Stirling engine was originally patented 200 years ago as a safer alternative to the steam engines, which were increasingly being used in mines, factories and textile mills, and which were killing and maiming the Reverend Robert Stirling's parishioners. It has been greatly improved since then and it is the most efficient heat engine so far developed.
Kevin Flanagan, Balsall Common The small print: Letters will not be included unless you include your name, full postal address and daytime telephone number (we prefer to use names of letter writers but you can ask for your name not to be published if you have a good reason). The Editor reserves the right to edit all letters.