Skip to main content
SLU publication database (SLUpub)

Report2008Open access

Pelletering och brikettering av jordbruksråvaror : En systemstudie

Nilsson, Daniel; Bernesson, Sven

Abstract

Use of processed biofuels (pellets, briquettes) has greatly increased in Sweden in recent decades, mainly to replace fossil fuels in large boilers, e.g. in coal powder boilers. More recently, the demand from private households and residential heating systems has also increased, mainly due to conversion from fossil heating oil. This increased interest in pellets and briquettes for heating is beginning to cause a shortage of the traditional raw materials, sawdust and wood shavings, and therefore attention is turning to using a variety of agricultural products as raw material. Such raw materials include cultivated energy crops and wastes and by-products from agriculture. This study describes the typical systems currently used for production of pellets and briquettes and investigates the possibility of using energy crops (Salix, reed canary-grass and hemp) and various wastes and by-products from processing of farm products (straw, cereal screenings, rape-seed meal and distiller’s waste) as raw materials. Previous experiences of pelleting and briquetting of these raw materials are reviewed in order to comprehensively identify possible combustion problems that may occur. On the basis of the results obtained, scenarios for possible production systems in a five-year perspective are presented and the costs and energy demands for these systems calculated. These future scenarios include largescale plants and micro-scale plants, as well as static and mobile equipment. The five main conclusions from the study are: o The farm raw materials of greatest interest for large-scale production are pelleted Salix and reed canary-grass. They have competitive prices and acceptable fuel properties and could be mixed with sawdust in existing large-scale pelleting factories in Sweden. o Straw has low production costs but can cause serious ash-related problems. Hemp has too high production costs to be of commercial interest, while distiller’s waste and rape-seed meal currently have a higher alternative value when used as protein feed. Cereal screenings can be a suitable raw material provided that they only make up a minor proportion in mixtures with other more problem-free raw materials. o The scale of production has a great influence on production costs. In large-scale plants, the machinery and equipment, etc. are used much more efficiently than in smaller plants, which results in lower costs. o Small-scale pelleting, both static and mobile, requires cheap raw materials and a high through-put to be profitable. In most cases, briquetting would be more commercially viable. o The energy consumption in manufacturing pellets from dry farm by-products is generally no higher than when moist sawdust is used as the raw material. More energy is admittedly required for cultivation and transport of farm by-products, but since there is no need for drying the total energy consumption is often lower. However, wet raw materials such as fresh Salix and distiller’s waste can increase the total energy consumption

Keywords

bioenergi; biobränslen; pellets; briketter; energigrödor; salix; rörflen; hampa; rest- och biprodukter; halm; avrens; rapskaka/rapsmjöl; drank; förbränningsproblem; produktionssystem; produktionskostnader; ekonomi; energiåtgång

Published in

Rapport (Institutionen för energi och teknik, SLU)
2008, number: 001
Publisher: Inst f energi och teknik, SLU