To qualify for participation in the 370-kilometre Energy Challenge,
vehicles had either to run on unorthodox fuels or rely on internal combustion
engines redesigned to be more energy-efficient.

The race began in Newcastle and, after a highly circuitous route, ended
in Sydney. The contestants were divided into 12 categories ranging from
electric, human-powered and hydrogen-powered vehicles to automobiles relying
on solar or wind power. One aim of the 1991 Energy Challenge was to refine
the formulae used to calculate and compare the emissions of carbon dioxide
from cars.

It took judges almost a week of computer calculations to decide the
winners. The judges, engineers from Australia’s largest motoring club, the
National Roads and Motorists’ Association, devised a new measure of vehicle
performance, called the Greenhouse Gas Index (GGI). They calculate the index
for a particular vehicle by multiplying the mass of the payload by the distance
travelled then dividing the answer into the grams of carbon dioxide generated
by the vehicle and by the production of its fuel.

Next year, the calculations will incorporate the levels of carbon dioxide
generated during manufacture and distribution of the vehicles as well. The
engineer in charge of the event, John Ward, said that it will take a year
of computer studies to arrive at acceptable values.

The organisers felt justified in judging electric cars by the same formula
because most Australian electricity comes from coal-fired power stations.
Solar-powered cars effectively had GGIs of zero. The GGI calculations were
not applied to human-powered vehicles this year because of the difficulties
in calculating the amount of carbon dioxide produced in the production of
food that competitors metabolise for energy. However, there are plans to
apply the formula to human-powered vehicles in 1992.

Competitors in cars run on internal combustion engines had to drive
with the maximum fuel efficiency without holding up the traffic or causing
a nuisance. A Daihatsu turbo diesel engine proved to be the most fuel efficient,
consuming 2.33 litres of fuel per 100 kilometres (121.2 miles per gallon).

The results of the analyses of the vehicles’ GGIs was full of surprises.
The clear winner among the internal combustion engine vehicles was a Mitsubishi
van powered by compressed natural gas with a GGI of 26 – lower GGIs having
less environmental impact – and an average speed of 47 kilometres per hour.
A compressed natural gas car came second with a GGI of 43 followed by a
diesel at 79 and several mixtures of unleaded petrol and ethanol.

The first battery car came in at eighth position of the 19 finishers
with a GGI of 119. The undisputed loser, and the veteran of the race, was
a 1992 Stanley Steamer which was powered by kerosene and had a GGI of 227.

The car was entered by the Biel Engineering School of Switzerland. It
was the first of many to finish from colleges and universities ahead of
entrants from major Japanese corporations such as Honda and Hoxan, which
claims to be the world’s largest manufacturer of solar cells. Of the first
15 cars to finish, 9 were from colleges and universities.

The winner covered the 3007 kilometre course at an average speed of
65 kilometres per hour in weather that was hardly conducive to solar car
racing. The Biel car was in the lead by the end of the first day’s racing
but the competition was kept eventful by freak storms, lightning, thick
cloud and heavy rain that flooded the highway.

One car, entered by the Danish Grundfos team, was lifted off the ground
by a twister, or miniature tornado, hurled 30 metres down the road and irreparably
damaged.

Biel’s win was made possible by solar cells developed by Martin Green,
a professor at the University of New South Wales in Sydney. The cells are
made from wafers cut from single crystals of silicon. The surface of the
wafers is then etched with a laser to convert the normally polished wafer
surface into the peaks and valleys of a mountain range. This process increases
the surface area of cells and hence the amount of sunlight they can catch.

The German electroncis company Telefunken and the British company BP
Solar – a subsidiary of British Petroleum – are both preparing to produce
the new cells commercially. The Biel car used pre-production prototype cells
made from Telefunken costing around A $400,000 (160,000 Pounds).

This contrasts dramatically with the cells used in the first Solar Challenge
in 1987 by the winning car, the GM SunRaycer. The gallium arsenide cells
used in the SunRaycer were reported to have cost around 600,000 Pounds and
offered similar efficiency to the new laser-etched cells.

Production versions of the Telefunken and BP Solar laser-grooved cells
will be considerably cheaper than the hand-made cells used in the Biel car.
BP Solar has said that production of the laser grooved cells should begin
at a new factory in Spain towards the end of 1991. In addition to their
low cost and high efficiency, Green’s cells avoid a major problem with gallium
arsenide cells – toxicity.

Once BP Solar’s Spanish factory is up and running reliably, a duplicate
factory would be established in Australia, the company says. This would
be important for Australia because of its strong dependence on solar cells
to power communications systems in remote areas. Telecom Australia was a
pioneer in using solar power for remote location power supplies and already
has 2 megawatts of cells in service powering telephone and microwave communication
links.

Two vehicles other than the winning Biel car used Green’s cells. They
were the Desert Rose from the Northern Territory University and the sole
British car, entered by Phil Farrand. The small number of the new cells
of the Desert Rose were made by hand in Sydney by Green’s team at the University
of New South Wales. The unknown number on the British entry were supplied
by BP Solar in Europe.

Farrand caused considerable speculation before the race when it was
discovered that he worked for Williams Grand Prix Engineering. The car was
not backed by Williams, however, and Farrand had bad luck and retired after
just 320 kilometres.

Each of the solar cars in the race gathered and converted between 1
and 1.5 kilowatts of electrical energy from the Sun when racing conditions
were ideal. Under a clear sky, 1 kilowatt of solar energy per square metre
falls on the cars. However, scattered low cloud cover can increase this
as sunlight bounces off the Earth’s surface, reflects off the underside
of the clouds and increases the total energy available. On one day of racing
the Biel team’s support vehicle recorded sustained levels of 1.3 kilowatts
per square metre and a 10 second burst of 1.8 kilowatts.

Another success story from the race came from the Australian Energy
Research Laboratories. Although it entered an old and damaged car with one
of the least efficient solar arrays backed up by a small lead-acid battery
with a storage capacity only 25 per cent of the value permitted for the
race, AERL’s car came in sixth – the first Australian finisher. Its success
was due to energy management.

AERL develops and manufactures low-cost computers which manage the conflicting
elements of solar power, battery storage capacity and the demands of an
electric motor. Eight of the first 10 cars to cross the finishing line used
AERL’s system, called the Power Maximizer.

The American car maker General Motors, which won the 1987 race with
its SunRaycer, chose not to enter last year’s race. But it did sponsor four
teams from American universities. These were chosen after a similar race
in the US last summer. A spokesman from GM said, ‘These are not the cars
of the future, but these young people are the car designers of the future.’

In spite of the successes of the race, Takahiro Iwata, manager of Honda’s
solar car project which produced the second fastest car in the race, believes
the future for solar-powered cars is bleak as solar cell efficiency is already
close to its theoretical limit. There is more hope, however, for battery-powered
electric cars and many of them will have solar arrays to recharge them while
they are parked in the sun.

The major drawback of battery cars is that current batteries are heavy,
inefficient and are made from materials which can be harmful to the environment.
But the development of a new type of battery in Japan last year may improve
the situation. The battery is actually a form of capacitor which holds electricity
as a static electric charge on two parallel metal plates separated by an
insulation layer. Conventional batteries store energy chemically.

Its developers, the car maker Isuzu and Fuji Electrochemical, say that
the new capacitor battery can store 30 to 50 times as much electricity as
the best existing capacitors and, weight-by-weight, has a capacity 20 times
as large as a lead-acid car battery.

The capacitor battery has a very low internal resistance so it can be
recharged in about 30 seconds and at much lower voltages than conventional
batteries. The new battery should be cheap and less harmful when discarded
because it it made principally from activated carbon and sulphuric acid.
Its developers hope to have batteries ready for sale within a couple of
years and are looking at applying the technology to electric vehicles.

A design for an internal combustion engine that was abandoned in the
1920s could make today’s engines much more efficient, quieter and cleaner.
So claims AE Bishop and Associates, a company based in Sydney, Australia.

The foundation of its new prototype engine is the resurrected rotary
valve that admits fuel into the combustion chamber and excludes exhaust
gases. The company claims that the engine offers a fuel saving of 5 per
cent and greatly improves efficiency.

The breakthrough was to build seals that are durable and leakproof.
The early pioneers of the rotary valve abandoned their objective in the
1920s because of difficulties creating an effective seal between the combustion
chamber and the valve.

Leaky seals compromise efficiency if they fail to contain combustion.
Likewise, lubricants sucked through a leaky seal into the combustion chamber
may burn, adding smoke and other pollutants to exhaust gases.

AE Bishop and Associates has at last perfected an efficient rotating
seal. The first prototype has been in development for three years and operational
for 18 months.

Tony Wallis, who heads the project, says that the prototype started
life as a Honda motorcycle engine. Little of the original engine now remains:
a new cylinder head was cast. It contains a tube perpendicular to the engine’s
crankshaft. Uniquely, the tube has two apertures adjacent to the top of
the combustion chamber.

Midway along the tube is an oblique deflector plate which directs the
incoming charge of air and fuel into the combustion chamber. When the valve
has half-rotated, the swivelled deflector directs the spent gases down the
exhaust pipe instead. A spiral gear running the length of the engine’s cylinder
head turns the valve at half the speed of the crankshaft.

Because the valve rotates, the engine is exceptionally smooth, quiet
and free from vibration. In a conventional engine, poppet valves reciprocate.
The accelerating and decelerating masses generate vibration and noise in
the cylinder head. This vibration does not occur in the Bishop Rotary Valve
because it runs in roller bearings.

A conventional index of engine efficiency called the Brake Mean Effective
Pressure measures the average pressure on the piston during the power stroke.
It is typically around 120 pounds per square inch, whereas in the first
prototype of the rotary valve engine, it was 165 psi.

One major feature of the rotary valve is the speed with which it opens,
and its integrity. Conventional engines based on poppet valves lose most
efficiency at half-throttle, the transition between opening and closing
a valve. The rotary-valve engine has an edge here because the aperatures
are opened and shut so crisply.

Also, engines generally run more efficiently at a higher compression
ratio. The introduction of low octane unleaded petrol has forced many car
makers to reduce compression ratios dramatically to 8.5:1 or less. The rotary-valve
prototype is already operating at 10:1 and calculations show that it will
operate satisfactorily at 14:1.

The World Solar Challenge takes five or more days to make the journey
from Darwin in the North to Adelaide in the South across the remote barren
terrain of central Australia. In late spring the Sun’s energy falling on
the competitors’ vehicles is about 1,000 watts per square metre. With current
solar cell technology, the top cars will achieve speeds of over 100 kilometres
per hour on little more than 1 kilowatt of power.

The participants are mostly entered by car manufacturers and universities
in Australia, Japan, Europe and the US, and are fiercely competitive. The
car entered by Honda was sent to Australia twice for track testing on a
cattle truck road in the Northern Territory. Each time it was returned to
Japan for alterations. The first World Solar Challenge across Australia
took place three years ago and was dominated by the Sunraycer, entered by
the American company General Motors. It used solar cells made from single
crystals of gallium arsenide. These cells converted the energy from sunlight
into electricity with an efficiency of over 18 per cent.

This was the highest available efficiency for solar cells at the time,
but gallium arsenide cells are difficult to make and very expensive. The
normally chatty public affairs staff from GM were reticent when asked but
conservative estimates put the cost for the solar array that powered the
Sunraycer at 750,000 Pounds.

The intervening three years have seen dramatic progress in the efficiency
of silicon cells which are much cheaper and easier to make, The semiconductor
industry has refined techniques for fabricating devices in silicon over
decades of miniaturising intergrated circuits.

Many of the 26 car which started racing last Sunday have solar arrays
offering better than 18 per cent efficiency greater than 18 per cent efficiency
from silicon cells.

Cell efficiency greater than 15 per cent is now being achieved for less
than 10,000 Pounds per car, some teams claim. Cars using silicon cells with
18 per cent efficiency are reported to have cost little more than 15,000
Pounds.

Two vehicles are using a new type of silicon cell developed by Martin
Green, a professor at the University of New South Wales in Sydney. He claims
a peak efficiency in the laboratory exceeding 24 per cent. Mass produced
versions of the cells, already being manufacturered in Australia, Spain
and Germany, can still achieve an efficiency of more than 18 per cent.

The cells are made from wafers of a single crystal of silicon and their
surface is etched with a laser to increase its area. Conventional cells
have a polished smooth surface but the surfaces of the new cells resemble
the peaks and valleys of a mountain range.

The German electronics giant Telefunken and the British company BP Solar
are both now manufacturing Green’s cells. The car entered by the Engineering
School of Biel in Switzerland uses cells manufactured by Telefunken. The
entry from the Northern Territory University of Darwin uses cells made on
a pilot production line being developed at the University of New South Wales
by Green’s team.

The 1987 Solar Challenge saw Japanese teams trailing a long way behind
American and Australian cars. The first Japanese entry to finish was beaten
by one from an Australian technical college. In contrast, the 1990 race
has attracted most of Japan’s automobile and electronics manufacturers.

Honda has designed a car weighing only 140 kilograms and with a drag
coefficient of only 0.12. Powered by a 4.5 kilowatt motor weighing 7 kilograms,
the solar-powered Honda has a top speed of more than 120 miles per hour.

However, prior to last week’s pre-race warm-ups, Honda has not tried
out the dormobile vans they had hired as support vehicles. They had a top
speed of 110 km/h, so proved too slow. On the eve of the race, Honda’s support
crew had to return the camper vans and replace them with more powerful cars.

Toyota’s Blue Eagle has a Stirling engine to supplement the electricity
generated by the solar array. Stirling engines can convert the sun’s heat
directly into mechanical power.

One car with a lot to gain from the race, though it is certain to lose,
is the Southern Cross. It was entered by the Semi-conductor Energy Laboratory
of Japan, in conjunction with Mazda, and uses cells which are less than
half as efficient as most other vehicles in the event. Most cars have solar
arrays capable of developing 1.0 to 1.4 kilowatts of power. The Southern
Cross’s array develops 0.6 kilowatts.

SEL is using a different type of silicon cell which is made from amorphous
silicon. In this type of silicon the atoms are arranged randomly unlike
the regular structure of monocrystalline silicon. Amorphous silicon techology
costs many times less than crystalline silicon cells. The cells are also
thinner (typically only 1 milimetre) and can be moulded to curved shapes
as they are not cut from single crystals. Amorphouse cells also use less
energy to manufacture.

This price advantage means these will be the first affordable type of
cells to be put into large-scale production for solar-assisted electric
vehicles. Though its top speed is only 70 km/h, the SEl Southern Cross may
be the eventual winner by offering the most cost-effective alternative to
the internal combustion engine.