Supplying the Pfunda Tea Factory, Lake Kivu, Rwanda

Supplying the Pfunda Tea Factory, Lake Kivu, Rwanda, Democratic Republic of Congo
Michel Halbwachs

Kivu Lake between Rwanda and the Democratic Republic of Congo, contains an enormous quantity of dissolved methane. Exploiting this methane is a fabulous opportunity for the economic development of this region. This gas also constitutes a risk of cataclysmic explosion, as occurred in Cameroon at Nyos Lake. A scientific French and Swiss group studied the physicochemical characteristics of the lake and evaluated the risk of a gas explosion. The Company Data Environnement has set up a pilot station to extract the methane for energetic purposes and proposed the promotion of this gas for diverse applications.

Annual wood consumption of wood by Pfunda was of about 4300 steres in 2003. This quantity would take the equivalent of 650 000 Nm3 of methane, thus leaving an excess of 950 000 Nm3 of gas, the equivalent of 760 000 litres of fuel oil.

Figures for wood consumption 2004 - 2009 are even higher, because provisions envisage 5800 steres of wood per year (which would correspond to a maximum consumption of 27 steres per day). Thus the quantity of methane which could be sold to Bralirwa would be 730 000 Nm3 per year, the equivalent of 585 000 litres of fuel oil.

Economic study
Some figures

In these evaluations, the following energy equivalents are assumed :
- PCI of a M3 of methane = 34 000 Kj
- PCI of a litre of fuel oil = 42 000 Kj
- I litre of fuel equals 1.25 Nm3 of methane (Nm" at 0°C and at atmospheric pressure)
- 1 MNm3 of methane = 800 tep (tonne equivalent petrol)

The calorific energy of wood (generally eucalyptus in Rwanda) is more difficult to estimate. According to what has been written, the weight/volume ratio for a cubic metre (stere) of wood varies between 300kg per stere and 500 kg per stere. We believe that a value of about 350 kg/stere is close to reality.

The PCI of wood will amount to 15 000 Kj/kg. The comparison between wood and gas on the level of energy works out at : 1 stere of wood is equivalent to 150 Nm3 of gas - that is about 5 GJ.
Prices in Rwanda in August 2004 were as follows :
- 1 stere of wood = 5 000 FRW, that is 7.15 euros or US$8.6
- 1 litre of fuel oil = 350 FRW, that is 0.5 euros or US$0.6 (1 euro = 700 FRW = US$1.2)

Comparison of the price of wood and the price of fuel oil in energy terms
- Fuel oil : 1 GJ = 12 euros = US$14
- Wood : 1 GJ = 1.36 euros = US$1.65

Note that the price of fuel oil is currently 8 or 9 times higher than wood, a fact which cannot be discounted in looking at the economic reality of the country : it would be difficult for methane to be cost competitive with wood. Methane would however be exceptionally competitive as a substitute for fuel oil.