The paper says that cowdung can perhaps be integrated into the strategy for better fuel making without any special stove design for cowdung cakes; fuels based on agro-residues and cowdung should be dealt with as a separate development task.
H S Mukunda, P J Paul and N K S Rajan are in the Department of Aerospace Engineering, and S Dasappa is in the Centre for Sustainable Technologies, Indian Institute of Science, Bangalore; Mahesh Yagnaraman and Mukund Deogaonkar are in First Energy Private Limited, D. Ravi Kumar is in Energy Division, GE, New Delhi.
The paper says that while wood and agro-residues are both biomass, the amount of agroresidues used on a per household basis is nearly twice that of wood. While it is generally understood that wood use itself is inefficient, the degree of wastefulness of agro-residues is enormous, a fact about which there is little appreciation all-round.
If developing improved cook stoves on firewood is considered important, it is far more important to develop stoves to burn agro-residues that are light and odd shaped to obtain high efficiency and reduce the emissions. The magnitude of the use of cowdung cake as a source for fuel is non-insignificant, but its use is about as energy-inefficient as agro-residues. However, the emissions from its use are significant and any improvement in the use of cowdung cake should address this aspect as well.
Coal is used in a wasteful way largely because of ignition problem. Many of the stoves are lit in the open for the volatiles to escape (about 30% in comparison to biomass with 70% volatiles) until coal becomes virtually coke and its combustion becomes vigorous. China that has encouraged a large production of coal-powder based beehive briquettes has serious indoor air pollution problems related to this fact, the Paper says.
