University of Vaasa - Vaasan yliopisto

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expeller, olive cake and wood pellet are commodities easily to be purchased and they
require less processing for combustion. Elghali et al. (2008) report that security and
stability of bio-energy supply chains may be enhanced by using both domestic and
imported biomass. Madlener and Bachhiesl (2007) point to the availability and
security of a local (regional) fuel supply as important issue for the establishment of
bio-energy systems. In this context, Puy et al. (2008) mention the severe impacts of
forest fires to supplier guarantees in the case of Mediterranean countries.
Other purposes of bio-energy supply chains
Some studies refer to additional major objectives apart from energy production when
introducing bio-energy systems. In this respect, Berglund and Börjesson (2006) and
Börjesson and Berglund (2007) highlight the reduction of plant nutrients leaching
from arable land by anaerobic biogas production and the subsequent use of the
digestate as a fertiliser. Furthermore, land filling may be replaced by more
sustainable waste management systems, into which, for instance, biogas production
(fermentation) of municipal or industrial organic waste are involved. In Sweden, the
national waste handling policy bans landfilling with organic waste and stipulates the
use of biological treatment methods (such as anaerobic digestion or composting) of
wet organic waste. Sewage sludge and waste water represents indeed a considerable
part of today’s total biogas production in Sweden, amounting to approximately 3
PJ/year out of a total of 5 PJ/year.
Discussion
Given the large variety of different bio-energy system designs and, in addition, the
rather high flexibility in operating them, a sustainability evaluation necessarily has to
look at the specific conditions of the individual bio-energy system under
examination, taking the whole system into account comprehending the components
biomass resources, supply systems, conversion technologies, and energy services.
Sustainability evaluation has to consider the “triple-bottom line”, comprising and
integrating economic, ecological and social aspects of sustainability (Elkington
1997). Our literature review shows that SCM and logistics issues are assigned a
crucial role for ensuring the sustainability of bio-energy systems. This starts when
deciding over the basic structure of the bio-energy system (feedstock, conversion
technology, end application) (Caputo et al. 2005) and continues with specific
questions of transport, handling, warehousing and storage systems (Ayoub et al.
2007) or of pre-treatment procedures of biomass feedstock (Uslu, Faaij & Bergman
2008).
The literature analysis shows that the energy balance (bio-energy output minus fossil
fuel input) differs significantly according to transport distances, feedstock and
conversion technologies (Börjesson & Berglund 2006, 2007; Caputo et al. 2005;
Madlener & Bachhiesl 2008; Puy et al. 2008). Additionally, economic viability must
be clearly distinguished from a positive energy balance. While the energy balance of