Environmental Engineering Reference
In-Depth Information
ciency of the stoves. The first step to improving these stoves is a better design that
would consume less fuel wood, charcoal, manure, agricultural wastes, or kerosene.
Metallic stoves or stoves with thermal insulation are also up to 25% more efficient.
Through subsidies and financing, several programs in Africa, Asia, and Central
America have succeeded in disseminating more efficient stoves in rural areas and
in the periphery of cities, or in poorer areas.
The efficiency of cooking stoves could also be improved through a requirement
that their fuel source be switched to propane (liquefied petroleum gasā€”LPG).
Such a transition would result in a dramatic reduction in pollution: a gas stove
emits 50 times fewer pollutants and is five times more efficient than a primitive
stove.
The modernization of biomass usage is one of the great challenges we face, and
there are already several methods for doing this, both nonbiological and biological.
Among the nonbiological processes is direct combustion of wood for the pro-
duction of heat and electricity. Other processes include using charcoal for cooking
and steel production, and gasification of carbon-based materials for the production
of synthetic gas, methanol, or other products.
Among the main biological processes are:
- Anaerobic digestion of biodegradable materials for the production of methane, which
can be done on a small scale in domestic biodigestors or on a large scale in sanitary
landfills or treatment stations for urban liquid effluents;
- Fermentation of sugars (mainly from sugarcane) for the production of ethanol, used to
replace gasoline in automobiles; and
- Saccharification (through enzymatic hydrolysis of cellulosic materials, such as plants)
followed by fermentation of the sugar. Cellulose is made up of long strings of sugars.
Recent increases in modern biomass use have been seen in a number of European
countries, particularly Austria, Denmark, Germany, Hungary, the Netherlands,
Sweden, and the United Kingdom, and in some developing countries. An estimated
56 GW of biomass power capacity was in place by the end of 2009.
What are hydroelectric plants?
Large dams are usually defined as dams with a height of 15 meters or more from
their foundation. If dams are between 5 and 15 meters high and have a reservoir
volume of more than 3 million cubic meters, they are also classified as large dams.
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