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", explains Fueyo, who says this technique is "not competitive, but makes use of the heat to offset the costs of generation". However, the researchers point out that "directly applying this waste to agricultural land as fertiliser could contaminate groundwater with nitrates".
In order to evaluate the potential and the cost of generating electricity, the researchers applied the methodology in municipal areas (in the case of solid urban waste and sludge from water treatment plants) and regional areas (for livestock slurry) throughout the whole of Spain.
The work shows that the centre and south of the Iberian Peninsula, the Balearic and Canary Islands have the "greatest interest" in putting technologies into place to use solid urban waste.
In terms of using water treatment plant sludge, the coastal areas of Galicia. Valencia and Alicante, as well as central and southern Spain, were also areas of interest. The study also shows that certain areas of Aragon, Castilla-La-Mancha, Castilla-y-Len, Extremadura, Galicia and Andalusia "would be effective" for using livestock slurry.
The EU 20-20-20 package
The research into electricity generation comes in response to the European Union (EU) objective to fulfil the 20-20-20 package for the year 2020, in other words to substitute 20% of the total energy consumed in Spain for energy from renewable resources, reduce CO2 emissions by 20% in comparison with 1990 figures, incre
FECYT - Spanish Foundation for Science and Technology