杏吧原创

The charcoal burners

Question: In the 1930s, Robert Byron wrote in The Road to Oxiana
that he had seen charcoal-powered cars being road-tested. Does anybody have any
information on charcoal as a fuel for automobiles, and were such vehicles ever
produced in any numbers?

Answer: Charcoal-powered cars were not uncommon throughout the Second World
War, when strict petrol rationing deprived most civilians of the use of their
cars.

Inside a generator attached to the back of the car, charcoal was burned in a
restricted air supply to make a product known as 鈥減roducer gas鈥濃�攁 mixture
of carbon monoxide, nitrogen and some hydrogen, this last coming from any
residual moisture that was present in the atmosphere.

Producer gas is still used in many industrial furnaces. It is sometimes
calorifically enhanced by introducing waste steam into the generator to increase
its hydrogen content, producing what is then known as 鈥渨ater gas鈥�.

For cars, the gas from the generator was stored at low pressure in a large
impermeable fabric balloon that was strapped to the roof. The gas was fed from
the balloon to the standard petrol engine via a modified carburettor.

These bag-flapping monsters generated even more hilarity than gas as they
careered along the roads鈥攗sually in rural areas. But they worked. Examples
have also been seen more recently in China and Albania.

Robert Byron, the source of your correspondent鈥檚 information, planned to use
this fuel to power a Rolls-Royce automobile on a tour of the Middle East in the
1930s. He intended to visit northern Afghanistan, where he would not have been
able to obtain petrol in those days.

His answer to the problem was both innovative and resourceful but, sadly, he
did not get the chance to put his plan into practice: the Rolls was not
delivered to him in time for his journey.

Peter Lloyd

Bolton-upon-Dearne, South Yorkshire

Answer: With experience and proper maintenance, good results could be had
from vehicles that were adapted to run on producer gas in the Second World War.
A 1934 eight-cylinder Pontiac coup茅 could keep up an average speed of 64
kilometres per hour over a considerable distance. Consumption of charcoal was
around 220 grams per kilometre.

Lorries were also converted to run in this way. A 2-tonne Chevrolet truck
carrying a load of 22 tonnes managed an average 25 kilometres per hour and
consumed around 300 grams of charcoal per kilometre. This was supplemented by a
sixth of a litre of petrol per kilometre.

Drawbacks were numerous. As well as the cost and trouble of conversion, new
driving techniques had to be mastered and there was a significant loss of power
compared with petrol driving. Additionally, the gas contained a high proportion
of carbon monoxide and was highly dangerous if the equipment was not
scrupulously maintained.

The charcoal had to be of high quality otherwise the
equipment鈥攚hich was not expected to last even half the lifetime of the
car鈥攚ould wear out even more quickly. Every 160 kilometres or so, used
fuel had to be raked out and the generator refilled with water and charcoal. In
addition, there was a warming-up period before the car could even be driven.

Not surprisingly, petrol, once it was widely available again, soon ousted
producer gas.

Sarah Wright

Aboyne, Aberdeenshire

Answer: During the Second World War, I worked for several years at the
British Coal Utilisation Research Association on developing gas producers that
could be fitted to cars and lorries. The engine was started using petrol, which
drew most of its air through the gas producer inlet. A burning rag was then
applied at the inlet so that the charcoal fuel ignited. Once the producer was
turning out combustible gas, the engine ran entirely on this fuel. However, the
gas had to be cooled and filtered before it entered the engine.

We also intended to run vehicles on fuels such as anthracite and coke
(bituminous coal could not be used because the tar blocked the filtering
system). Unfortunately, we found that these fuels were much more difficult to
gasify than charcoal, because their lower reactivity caused them to produce more
carbon dioxide and less carbon monoxide.

With these less reactive fuels, the initial reaction zone had to be insulated
with fresh fuel to minimise heat loss from this zone to the walls. The calorific
value of the gas produced rose significantly if a small amount of steam was
added to the inlet air, while the addition of sodium carbonate to coke improved
its reactivity significantly.

The end of the war came before this system had been carried into mass
production. However, in the future it may prove economical to run lorries on
charcoal in many parts of the world. This would not only provide a sustainable
transport system, it would also make no net contribution to the greenhouse
effect.

M. W. Tring

Africa Advisory Group

Brundish, Suffolk

Answer: I drove a modified charcoal-powered Studebaker Commander on some
journeys of more than 150 kilometres during the Second World War. If I was
running low on fuel I could quite happily augment the supply by using charcoal
from camp fires.

The pi猫ce de r茅sistance was collecting a few old leather boots
and, to the delight of a suitable audience, dropping one of them (boots, not
audience) into the fuel hopper鈥攖he smell gave the engine an extra
boost.

The main problem, as with all gas producers, was sparks and gas blowback,
which created an obvious fire risk, especially in the dry grassed areas and
narrow roads of Australia.

Fred Sanders

Lower Mitcham, South Australia

This week鈥檚 questions

Whence the whine? Last year our house was struck by lightning. Just before
the strike, which manifested itself as a simultaneous bang and flash, my wife
and I heard a strange noise. It lasted about 2 seconds and was similar to the
whine a jet aircraft makes when landing 鈥攁t first, we thought the house
had been hit by a plane. Does anyone know what caused it?

Carl Hampson

Sefton, Merseyside

Flying blind? When pilots of jet aircraft are coming in to land, or indeed
taking off, do they look out of the window as the driver of a car would? Do they
steer, take off and land the aircraft by what they can see outside, or do they
rely on their instruments alone? If the latter, how?

Jim Jordan

St Helens, Merseyside