Page 432 - Advances in Renewable Energies and Power Technologies

1. Introduction 405

A detailed study on choices for domestic fuels within this framework is that by
Bisu et al. [5].
In some regions, the cost of firewood can be higher than the cost of the food it-
self, raising food safety issues.
Biomass amounts to around 10% of world primary energy consumption (fire-
wood, agricultural residues, dung, and waste). The World Health Organization esti-
mated that the use of biomass fuels and charcoal for cooking and heating accounts
for 10%e15% of global energy use [6]. It is the fourth energy source at world level
behind oil, coal, and natural gas and can be around 80% of primary energy con-
sumption in undeveloped countries. Precise data are difficult to gather because
of the noncommercial nature of the directly collected biomass. Firewood used
worldwide for household cooking is around 50% of the total, according to diverse
sources.
Obtaining biogas in anaerobic digesters from collectible soft organic residues is
one possibility of distributing a clean and renewable fuel for small communities [7].
In some places, feedstock and manure biomass consumption compete with fertil-
izers; but in other areas, its use as fuel is a way to manage excessive biological res-
idues, e.g., Chen et al. [8]. In periurban areas, digesters seem inappropriate because
of space requirement, odors, and insects.

1.2 COOKING WITH WOOD AND THE ASSOCIATED HEALTH
PROBLEMS
One main problem with combustion in poor dwellings is indoor air pollution; actu-
ally, it is common smoke. Toxic gases are produced, such as carbon monoxide (CO),
unburned and partially burned hydrocarbons (noncondensing hydrocarbons), and
flying particles (ash, tar, and cinder). This is a problem also for not-so-low-
income dwellings [9]. Breathing this polluted air daily leads to illnesses, including
stroke, ischemic heart disease, chronic obstructive pulmonary disease, and lung can-
cer [10e12] among others. For the poorest dwellings, an effective chimney is
frequently nonexistent but only small ventilating apertures. Two to four million pre-
mature deaths worldwide per year are attributed to this cause [13,14], decreasing
GDP, e.g., Naciones Unidas/OCDE [15].
Indoor domestic air pollution is higher as a result of the low efficiency of the
cook stoves used, mainly open fire and frequently on the floor (three-stones cooker).
The energy efficiency is typically not higher than 15% of the lower heating value of
wood [16]. This translates into an increased amount of hot fumes. Because these are
used for indoor space heating and eventually smoking hanged meat, this method
does not promote ventilation. Mainly children and women breathe polluted air for
a prolonged period. Also, they spend many hours gathering wood, which is difficult
in the initial stages of economic development, and augments risks of accidents,
kidnapping, being prone to attack by wild animal, and being affected by articular
lesions. This duty also precludes children going to school. Cultural and gender issues
can aggravate this problem [17].