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Last Updated: Tuesday, 28 December, 2004, 02:44 GMT
Steam engines could be eco hope
By Jo Twist
BBC News science and technology reporter

Think of steam engines and hazy, romantic images of chugging great beasts of old fill the mind.

The Inspiration steam car design
Inspiration aims to break the record next summer
Steam-powered vehicles are not usually deemed as being parked at the cutting edge of transport technology.

Nor do they seem to be the type to race across desert landscapes in a bid to smash land speed records in the 21st Century.

But British design engineer Glynne Bowsher and his team have almost finished building a super-fast vehicle reminiscent of the Batmobile.

And this car puts a new technological breath of life into what is regarded as a traditional means of power.

He knows engine and vehicle design like old friends, having worked on Richard Noble's record-breaking Thrust 2 jet car and having designed ThrustSSC, the first vehicle to break the sound barrier on land.

His team, the British Steam Car Challenge (BSCC), is hoping that its Inspiration vehicle will live up to its name and not only break a long-standing steam-car speed record, but also inspire thinking about alternative fuels for the future.

In and out

The search for a suitable alternative fuel source to hydrocarbons which can cleanly power our vehicles has touched on various different options.

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.

Construction: Tubular steel spaceframe with composite/metal panels
Length: 5.25m
Width: 1.70m
Height: 1.10m
Fuel: LPG (Liquified petroleum gas)
Working fluid: Water/steam
Performance: Maximum speed 200+ mph (320km/h); Initial acceleration: 0.52G
Brakes: Twin front wheel brakes and twin rear inboard rear disc brakes
Steering: Rack and pinion
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 are most likely to 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.

Steam lad

Inspiration is a far cry from the steam cars made famous by the Stanley brothers, however.

The 1906 record, set by a Stanley Steamer at what is now Daytona Beach, is the longest-standing officially recognised land speed record for a steam car.

It was set at a time when the battle for supremacy between petrol-powered internal combustion engines and steam-powered external combustion engines was in full sprint.

Although Stanley Steamers had enjoyed a boom in the early 1900s, they were quickly being overtaken by internal combustion engines.

Design engineer Glynne Bowsher
I grew up with steam locomotives in my own town, so steam was a part of my life
Glynne Bowsher

The steam car, driven by Fred Marriott, reached 127.7mph (205.5 km/h), beating four petrol-powered vehicles to pick up the Dewar Trophy rewarding the fastest vehicles on land.

Even before steam became speedy, a steam-powered engine designed by Nicolas Joseph Cugnot drove the first self-propelled vehicle in 1769.

But it had to rest every 15 minutes to generate enough steam power to send it on its way again.

To Mr Bowsher, it is steam's historical legacy that has always attracted him.

"I grew up with steam locomotives in my own town, so steam was a part of my life. When I was young we didn't have a car - my father never owned one," he explains.

"We went on the railway or the bus. It was quite important to me; I always had a love of aviation and steam so those two things in terms of transport are still with me."

Own design

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).

Inspiration is designed to break the long-standing land-speed record for steam cars

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."

Two stage turbine on single spool
Output: 300bhp at 12,000rpm (turbine speed) (225kw)
Output shaft gear ratio: 4:1 or 4.45:1 to twin output shafts
Differential: Epicyclic type with viscous couplings
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.

Green fuels set for breakthrough
13 Jul 04 |  Business
UK boost for biomass fuel crops
19 Oct 04 |  Science/Nature
Looking to the hydrogen horizon
21 Sep 04 |  Science/Nature
Sun and hydrogen 'to fuel future'
12 Aug 04 |  Science/Nature

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