DESIGN AND SIZING OF A DIGESTER COUPLED TO AN AIR SOLAR COLLECTOR - Energy Research Developments: Tidal Energy, Energy Efficiency and Solar Energy - page 153

Table 2. Estimation of biogas production with respect
to digestion temperature - energy equivalent [1, 4, 5]

Digestion
temperature
(C°)

Equivalence in
wood for heating
(kg)

Equivalence in butane
gas standard cans
(13 kg)

Biogas monthly
Production (m 3 )

15 - 20 68,4 342 1

20 - 25 126,9 634,5 2

25 - 30 145,5 727,5 2

35 - 40 185,4 927 3

Conclusion

The proposed family digester is inspired by the an Indian model. It is primarily made up
of an digestion enclosure, an evacuation and feeding system of the digestion substrate and a
biogas storage bell. Its sizing allows a daily contribution of 130 litters of wet biomass made
up mainly of cows' dung. The digestion temperature is ensured thanks to the use of a low
temperature heating system which uses air solar collectors and of a storage system made up of
a stones bed. The sizing of the system is carried out by taking into account a digestion
temperature of 40°C. At the end of a residence time fixed to 90 days, the monthly production
of biogas is estimated to 68,4 m 3 for a digestion temperature ranging between 15 and 20°C.
This production can reach 185.4 m 3 of biogas for a digestion temperature ranging between
35 and 40°C, which is the energy equivalent of approximately 3 butane cans (13 kg) or
927 kg of wood which could be preserved. Hence, the use of biogas in the rural zones would
constitute a very good substitute for heating wood and an important support to the national
programs against deforestation and desertification.

References

[1] S. Igoud, I. Tou, Kehal.S, N. Mansouri et A. Touzi. Première approche de la

caractérisation du biogaz produit à partir des déjections bovines . Rev. Energ. Ren.
Vol.4. 123-128 (2002).

[2] S. Igoud. Réalisation d'un digesteur familial de 15 m³ . Fiche technique. Document

interne, Centre de Développement des Energies Renouvelables (2004).

[3] P. Lunde. Solar Thermal Engineering . Edition John Wiley and sons, 612 p. (1980).

[4] N. Baek. Analyse Technico-économique d'un Système Solaire de Production d'Air

Chaud pour le Séchage du Tabac « Virginie » et le Chauffage d'un Bâtiment . Thèse de
Doctorat, Univ. de Perpignan, 195 p. (1984).

[5] Ludwig Sasse. L'installation de biogaz , Ed. GATE-GTZ, 89 p. (1986).

[6] B. Lagrange. Biométhane. T1: Une alternative crédible . Ed. EDISUD, 204 p. (1979).