Evaluation of fuel pellets as secondary product when pressing oil from grapevine seeds

Abstract

© 2018 Latvia University of Agriculture. All rights reserved. In recent years, there is growing importance of a new non-waste technology in wine industry that contributes to environmental protection. Relatively frequently vineyard waste wood cut off during winter time is used to produce fuel pellets. Another option is the use of grape marc for the briquettes production and then for further production of energy or gaining oil by pressing the separated seeds. This paper discusses the evaluation of pellets features from cakes of grape seeds from the energetical point of view as well as from the point of compliance with the standards for production of pellets. The calorimetric measurement was first determined by the calorific value of the pellets of grapevines wood, seeds, grape marc and cakes. The pellets of the separated seeds had the net calorific value of 19.54 ± 0.67 MJ·kg-1 compared to those from grapevine wood pellets 16.39 ± 0.18 MJ·kg-1, seedless grape marc pellets 16.85 ± 0.46 MJ·kg-1 and cake pellets 18.60 ± 0.72 MJ·kg-1. The smaller net calorific value of cake pellets compared with the pellets made from seeds is due to the reduced amount of oil-based substances in cake produced during the oil-pressing process. The quantity is reduced by 40-60 %, yet the calorific value is satisfactory, when compared to other types of fuel. When carrying out the pellet test, emissions were analysed and in most parameters complied with national as well as international standards. Double amount of sulphur content has been found in cake pellets, which has negative effects on the environment. The content of chlorine was slightly higher, around 0.11 % compared to the limit of 0.1 %, which negatively affects the combustion equipment. A possible solution to reduce these over-limit values is to mix pellets from cake with other pellets. The mixture that meets all emission requirements and reaches a calorific value of 17.36 ± 0.06 MJ·kg-1 was tested and is finally made up of 50 % of seedless grape marc, 30 % of grapevine waste wood and 20 % of cake.