Natural gas is generally transported by gas
pipeline when it is a question of supplying large users, concentrated geographically,
or also if distances are quite short (less than 15 km). But when consumption is
widely spread geographically over distances ranging from 20 to 200 km and the
quantities of an industrial dimension, but not too large - 160 000 to 600 000
m3 per day - there are advantages in transporting the gas in a compressed form
Apart from industry, potential gas users in Rwanda, in particular
those currently using wood, are of these types :
- tea and coffee
factories are scattered at distances between ?? and ?? from Kivu and have total
energy needs of between 100 000 and 200 000 Nm3 per day, not including their needs
in electricity, which could also be self generated using gas.
or small energy-dependent businesses are very spread out but often along the roads,
with energy needs of between 30 000 and 100 000 Nm3 per day.
the face of it, all the conditions for profitability of transport of CNG by lorry
In order to take up a small space,
the gas has to be compressed at the high pressure of 200 b, which requires a fairly
robust container, usually made of steel or in composites which are more expensive
Normally these containers are cylinders piled on a 20 to 30
tonne lorry trailer, cylinders which contain between 3 000 and 7 000 Nm3 of gas
at a pressure of 200 b.
of a haulage vehicle an d its trailer with steel containers
of containers in composite materials
In order to exploit this expensive equipment, particularly
containers, in a profitable way, they have to work together, ferrying efficiently,
with generally speaking 3 trailers for each hauling vehicle : one trailer being
loaded at the gas source, one out on the road and the third delivering the gas
to the customer.
Unloading is optimised by grouping 2 or three consumers
or by installing an intermediate storage point allowing for speedy discharging
of 200 b to 75 b, in a buried wide-diameter pipe, for example.
of a trailer park with steel tubes used on a Canadian gas field (Quebec).
of CNG with other types of energy should be good, and even more so if, in addition
to the thermic use of the gas (heating, drying etc.) in small scale agribusiness
or for construction material, auto-production of electricity was developed or
distribution by small networks to community groups or neighbourhoods for domestic
purposes like lighting or cooking. Among competing energy sources, wood could
stay competitive for a time but it will become rare, higher in price and the object
of a probably more and more severe conservation policy for the forest. As for
fuel oil, it should stay a lot more expensive for the foreseeable future.
setting up of a legal framework for the distribution of CNG can be simple and
would concern :
- Apparatus under pressure
- The transport
of CNG and the safety factor, this latter being mitigated by the fact that, natural
gas being lighter than air, it escapes vertically if there is a leak. Moreover,
there has never been an accident of CNG transport linked to the gas.
and the safety factor.