Daily life in Dar es Salaam, especially in Msasani where many foreigners live and work, is permeated by the steady grind of diesel generators. The electricity is off almost as much as it's on, and businesses, schools, and homes are left to generate power for themselves for irregular periods of the day and night. Of course, most Tanzanians can't afford electric power to begin with, and in urban areas their principle means of fueling stoves to cook and boil water is charcoal. The country burns roughly one million tons of charcoal annually, outpacing the reforestation rate by three to one. Using charcoal as fuel is significantly more damaging than firewood because its production requires the destruction of the entire tree, and a considerable part of the energy content of wood is wasted in the production of charcoal as well. Deforestation around urban zones like Dar es Salaam is particularly bad, and the forests of Pugu Hills Reserve just west of the city have been completely degraded despite modest attempts at conservation. Indeed on several birding excursions in the area, I have encountered men cutting down trees with machetes and processing charcoal, both inside and outside the reserve boundaries.
There are similar pressures on forests up and down the coast, although transportation costs add considerably to the price of charcoal the further one gets from Dar (not surprisingly diesel is almost $1.50 USD per liter). Charcoal production is typically conducted on a small scale, where farmers and colonists produce small quantities in local forests and sell them on the highways to middlemen passing through in lorries. Often, you'll see men on bikes peddling huge bags of charcoal to the nearest collection point or market, looking to add a modicum of value to their product by delivering it themselves. Similar economizing occurs on the demand side as well, and on trips in and out of the city, I've witnessed drivers stop at small farms along the highway to buy charcoal directly from the producers (our safari driver did this once on a trip to the Selous Game Reserve). What's the solution, then? Electric stoves certainly aren't feasible, and the cost of kerosene and gas stoves remains too high. On the supply side, making charcoal briquettes from wood waste products would be an improvement over lump charcoal, even better making briquettes out of paper and biomass waste, but production requires special machinery and binding materials. Creating more efficient stoves would certainly reduce the need for charcoal, but Tanzania's high population growth rate, which hovers around 3%, is a serious obstacle to a demand-side solution.
For a more detailed discussion of the issue, check out Jean Kim Chaix's article "Is a Charcoal Crisis Looming for Tanzania?"