Chemical characterization of pruned vine shoots from la Rioja (Spain) for obtaining solid bio-fuels

Abstract

Every year thousands of tonnes of biomass waste in the form of pruned vine shoots are produced in the Spanish region of La Rioja. This study, the first of its kind to be conducted in the region, examines how this waste can be valorised, mainly as an energy source. Representative samples were taken from the different varieties and vineyards in the region. Each batch of samples was then chemically characterised to learn its moisture content, percentage of ash, composition in terms of elements and heating power. The influence of various factors on these chemical properties was analysed. Only two factors proved to be of statistically significant importance: variety and training method. The expected performance in combustion of vine shoots of the region's predominant variety, Tempranillo, was estimated. Undoubted advantages were found, such as a significantly higher heating value (16 900 kJ/kg), moderate quantities of ash, medium aerosol emission rates, no expected problems of corrosion due to S or Cl, and a very low heavy metal content. In actual collection conditions, thermal energy from vine shoots after chopping (to between 30 and 100 mm), with a moisture content of less than 20%, would cost 2.45 euro cents/kWh to produce. The best way of using this residue is considered to convert it to fuel for generating heat and electricity on a small scale, to supply the needs of vineyards themselves or nearby locations. © 2013 AIP Publishing LLC.