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Washington, Feb 24 (ANI): In a new study, scientists from the University of Zaragoza have suggested that waste could generate up to 7 percent of electricity in Spain.

The researchers, from the University of Zaragoza (UNIZAR), calculated the energy and economic potential of urban solid waste, sludge from water treatment plants and livestock slurry for generating electricity in Spain.

These residues are alternative sources of renewable energy, which are more environmentally friendly and, in the case of solid urban waste, more cost effective.

Using waste to generate electricity has economic and environmental advantages.

“It gives added value to waste, because it can be seen as a type of fuel with zero cost, or even a negative cost if taxes are paid to collect it”, said Norberto Fueyo, lead author of the study and a researcher at the Fluid Mechanics Group of the UNIZAR.

According to the researcher, generating electricity from waste avoids “pernicious” impacts.

Waste in landfill sites releases methane and other polluting gases, so incinerating solid urban waste will reduce the volume of waste that reaches the landfill sites in the first places, as well as the implicit risks of landfills themselves (possible emission of methane into the atmosphere).

The study has shown that waste in Spain could generate between 8.13 and 20.95 TWh (terawatt hours).

“This electricity generation was 7.2 percent of electricity demand in 2008″, said Fueyo.

The researchers stress that the amount of methane generated from different kinds of residues is equivalent to 7.6 percent of gas consumption in 2008.

In terms of the economic cost, “solid urban waste is the most cost-effective”, according to the researcher, because local authorities carry out the waste collection and local inhabitants pay for it.

Since the waste is transported to large landfill sites or waste treatment plants, installing electricity generation systems “could take advantage of economies of scale due to the large volumes involved”.

According to the study, incineration of waste and degasification of landfill sites are the electricity generation technologies with lowest financial cost.

Producing electric energy through anaerobic digestion (a biological process in which organic matter decomposes into biogas in the absence of oxygen and through the action of a group of specific bacteria) is much more expensive.

“However, its profitability relies on being able to get value out of the heat generated during the process”, explained Fueyo, who said that this technique is “not competitive, but makes use of the heat to offset the costs of generation”. (ANI)