“Bawal blues”

The mounting cost of bawal firewood (kathi) has become a matter of concern for Parsis. In his article "Bawal blues” (Parsiana, December 7, 2007), Farroakh Govadia has reported that the cost of bawal escalated from Rs 40 per ton in 1942 to Rs 70 per ton in 1972 and is around Rs 10,000 per ton today. In a further letter (Readers’ Forum, Parsiana, February 21, 2007) Govadia has stated that of the all India demand of about 2,000 tons per year, Bombay city and suburbs alone consume 700 to 800 tons.

I have tried to calculate the break-up between the firewood burnt round the clock for 365 days in the sanctum sanctorum of the 50 or so agiaries and atash behrams as well as in public and private liturgical ceremonies in Bombay.

But first, the basic principles. Firewood contains about 80 percent volatile matter and about 20 percent fixed carbon. Experimental and theoretical studies have indicated that the volatile burning rate varies from 0.64 to 2.4 mg/sec sq cm cross section. After the volatiles have escaped, the residual fixed carbon burns at about one-tenth the volatile burning rate (Sunavala P. D., Indian Journal of Technology, Vol 20, February 1982, pp 41-49).

In view of the approximations involved, it is not possible to calculate the exact figures. However, assuming a mean burning rate of 1.2 mg/sec sq cm cross section and a 232 sq cm cross section (a 9” x 4” log on the hearth), a simple calculation indicates that 439 tons per year of firewood would be burnt in the 50 odd fire temples in Bombay city and suburbs. The balance of the 700-800 tons per year of firewood would be burnt in private and public liturgical ceremonies. In short, about 55-62 percent of the total firewood is burnt in the sanctum sanctorum of the fire temples in Bombay. In towns where a single agiary caters to a small local population, the amount burnt could approach cent percent.

Dr P. D. SUNAVALA