Abstract
The objective of this paper is to investigate usability of rapeseed cake from biodiesel fuel production as an energy source. For this research, rapeseed was grown at the research site of the Faculty of Agriculture in Zagreb, Croatia. The investigated rapeseed cake, residue from cold pressing, was divided in two groups of samples. The first group was a mix of three varieties (Bristol, Express and Navajo), while the other group consisted of three hybrids (Artus, Baldur, Titan). The utilization of rapeseed cake for energy via two routes was evaluated; namely, utilization of rapeseed cake as (1) solid biofuel (pellets) with addition of 3% of glycerol, and (2) as substrate in anaerobic digestion (AD). In investigation of cake as solid fuel, proximate (moisture content, ash content, fixed carbon and volatile matter), ultimate (content of carbon, sulphur, hydrogen, oxygen and nitrogen) and physical and calometry analyses (abrasion, diameter, length, density, higher and lower heating value were carried out. As for its use in AD, production of biogas during 40 days was monitored with a view of assessing the use of digested residue as fertilizer in agricultural production. Both groups of digested residues were analysed (pH, electroconductivity, moisture content, ash content, content of nitrogen and carbon, C/N ratio, content of P2O5, K2O, Ca, Mg, Na). The analysis indicated that the investigated raw material is usable as solid and gas biofuel, and digested residue as fertilizer in ecological agriculture. The two groups of samples analysed here did not show significant differences.
Highlights
The development of biodiesel production during the past thirty years has been rapid, from so called “backyard production” to industrial-scale production, and this fuel reached a significant role in arable and livestock farming (Krička et al, 2007)
All member states of the European Union (EU) and most of the transitional countries have introduced biodiesel production based on different scenarios pending on their needs, use of different raw materials, manufacturers and, end users
In the Republic of Croatia oil rape is mainly grown for production of edible oil and grits or cake as by-product, which is used as a component in animal feed (Krička et al, 2004; Voća et al, 2008)
Summary
The development of biodiesel production during the past thirty years has been rapid, from so called “backyard production” to industrial-scale production, and this fuel reached a significant role in arable and livestock farming (Krička et al, 2007). It is assumed that an increasing biodiesel production in Croatia, based on Directive 2009/28/EC and Ordinance on quality of biofuels (Official Gazette 141/2005), will create a problem of disposal of rapeseed cake as a by-product from biofuel production. Following the experience of the EU countries with large production of biodiesel, it is estimated that the livestock farming, which in the last 20 years was reduced by half in Croatia, will not be able to absorb the amounts of cake generated in this process. Due to Tajana Krička, Ana Matin, Neven Voća, Vanja Jurišić and Nikola Bilandžija this and in order to maintain positive cost efficiency of biodiesel production at the EU markets which are saturated with this by-product, it is necessary to find new ways of using rapeseed cake
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