Environmental Engineering Reference
In-Depth Information
These limitations can be partly overcome by the utilization of lignocellulosic materials,
such as residues from agriculture, forestry, industry and dedicated crops (Cherubini et al.,
2009). The importance of recovering transportation biofuels and chemicals from
lignocellulosic biomass feedstocks is evident: they are the most abundant biomass source in
the Earth, they can be recovered from residue streams in different sectors, they can be grown
in combination with food (e.g. straw and corn stover) or in non-agricultural lands and they
have high potential for converting their main components (cellulose, hemicellulose and
lignin) into a wide spectrum of biofuels and chemical products (Kamm et al., 2006b; Katzen
and Schell, 2006).
Since this is a relatively new concept in the scientific literature, few published papers on
environmental performances of biorefinery systems are currently available. This work
addresses this aspect: after a definition of the biorefinery concept, a Life Cycle Assessment
(LCA) of a biorefinery system based on wood residues is reported.
The chapter starts with a formal definition of biorefinery and a list of criteria that a
bioenergy/biomass system has to meet to be a real “biorefinery”. Afterwards, the most
important biomass feedstocks, processes and platforms, related to the biorefinery concept, are
depicted and a comparison between biomass and oil as raw materials is presented. In order to
investigate all the environmental aspects of biorefinery systems, a case study is evaluated by
means of Life Cycle Assessment (LCA). The biorefinery system produces bioethanol, furfural
derivates, electricity, heat, biomethane, hydrogen and oxygen from wood industrial residues.
The biorefinery is compared with a reference system producing the same products from fossil
sources. Information concerning product yields and mass, energy, exergy and carbon
conversion efficiencies are also reported. Several allocation methods are used to share the
environmental burdens of the biorefinery among the co-products and the final results are
compared.
2.
A
PPROACHING
B
IOREFINERY
:
D
EFINITION
,
C
RITERIA AND
C
HARACTERISTICS
2.1. Background and Current Status
Among the several definition of biorefinery, the most exhaustive was recently performed
by the IEA Bioenergy Task 42 on biorefineries (IEA 2008) (Figure 2):
“Biorefining: the sustainable processing of biomass into a spectrum of marketable
products and energy”.
One of the main driving factors for the future development of biorefinery can be seen in the
efficient production of transportation liquid biofuels. The transportation sector is growing
steadily and in the same way grows the demand for renewable (bio-)fuels, which can only be
provided from biomass. Numerous countries have targets for improving the shares of biofuels in
the national transport sector.
