Technically Speaking

British design engineer Glynne Bowsher and his team has nearly completed their technologically advance steam-powered automobile. Their hopes is to smash the land speed record in the British Steam Car Challenge (BSCC). Not only that, they are hoping hat the vehicle in turn will spur the general public’s interest in cleanly powered vehicles.

Fuels which do not “rot” the environment usually bring to mind images of gently humming electric cars, clean hydrogen, natural gas, or hithane - a concoction of hydrogen and methane.

The most promising, believes Mr Bowsher, is either nuclear or hydrogen fuel.

The public is reluctant to explore nuclear; but researchers and engineers across the world are exploring how best to generate and, more importantly, store hydrogen fuel, one of the main barriers to its widespread use.

Nine European cities are taking part in a pilot scheme to use hydrogen fuelled buses on certain routes, for instance.

But until a viable mass-scale way of storing and distributing hydrogen effectively is developed, it remains limited in use.

Mr Bowsher believes that until then, designers could look to Inspiration for a different take on good old steam.

The key to its potential is the difference between internal and external combustion technologies.

External combustion engines - like steam ones - hold several advantages over internal ones.

They have the potential to produce fewer harmful nitrogen oxides (NOx) than conventional cars which use internal combustion engines.

Although steam engines still need to burn hydrocarbon-based fuels like petrol and diesel, which in turn release carbon dioxide, external combustion engines can control the release and the production of CO2 more efficiently.

And because such engines can work well at lower peak temperatures and pressures, the creation of NOx compounds can be almost negligible.

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Current performance metrics are; Performance: Maximum speed 200+ mph (320km/h); Initial acceleration: 0.52G. The current record stands at 763 mph, or Mach 1.02, set by Andy Green in the Thrust SSC II, in 1997. Bowsher’s design will have to nearly quadruple its maximum speed in order to break the record. I suppose he is a good candidate to do it for he worked on the Thrust SSC II and designed the Thrust SSC that set the land speed record in 1983 at 633 mph. Bowsher has designed his vehicle from the ground up.

Designing a steam engine fit for the demands of a 21st Century land-speed attempt has proved somewhat of a challenge, however.

“We basically had to come up with our own design, which is innovative in some ways,” says Mr Bowsher. So innovative, in fact, that the team is exploring patenting the design.

Inspiration’s engine works in quite a simple way, he explains.

Water is passed through a steam generator where it is heated by burning propane gas into superheated steam at 400C and at 40-bar pressure (4 million Pa).

That steam is then fed into four nozzles on a two-stage turbine arrangement.

“With a turbine, you either use the pressure energy or velocity energy. In this case, we turn the pressure energy into high velocity.

“Then the moving gas stream strikes the turbine wheels and starts them rotating - a bit like a small-scale power station,” explains Mr Bowsher.

“Once we have a turbine that goes round, rotational power, that along with gear ratios can be used to drive the wheels and once we have the wheels rotating we can make it go forward fast.”

It sounds simple enough, but there were big challenges technologically to generate enough power in such a small vehicular space - 300 brake horsepower to be precise.

That is 225kW of power operating at 12,000rpm. Formula 1 engines typically operate at more than 17,000rpm, while aircraft turbine engines turn at 85,000rpm and above.

“One difficulty was getting a turbine and transmission system in such a small space.

“But the worst problem was providing a steam generator to provide steam the turbine needed in such a small space.”

It is a method of steam production that seems not to have been used previously, according to Mr Bowsher.

He does not imagine that steam cars will be the complete road ahead for cars on our streets.

“Gas turbines have been used in the past,” he says. “But the problem of turbines is that to be efficient, they have to run at a predetermined speed.

“The very nature of road cars is that their speed changes all the time, so this design would be no good for road vehicles.”

But he can imagine the engine design being used in diesel-based commercial vehicles which belch out a large proportion of pollution, like buses and lorries.

“Burning propane is environmentally more friendly than burning diesel. If the technology could be adapted, then it might just be a possibility - it is something we are investigating,” he says.

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