Environmental Engineering Reference
In-Depth Information
Figure 2. Biorefinery recovers energy and materials from biomass sources.
For instance, Europe aims at a share of 5.75% in 2010 and 10% in 2020 of biofuels,
according to the draft directive for renewable energy, while IEA and IPCC expect a significant
contribution of biofuels on transportation market in 2030 (10 - 20%) (EBS 2007). The main
challenge for biorefinery development is therefore the efficient and cost effective production of
transportation biofuels, whereas for the coproduced biomaterials and biochemicals additional
economic and environmental benefits might be gained.
The most common biofuels produced today in the world are bioethanol, biodiesel and
biogas (or biomethane). Bioethanol production from sugar or corn starch was more than 17
Mtoe in 2005; United States (from corn starch) and Brazil (from sugar cane) are the largest
producers (GBEP 2007). Biodiesel, made by combining vegetable oil (from rapeseed,
soybean, sunflowers, canola and others) or animal fat with an alcohol and a catalyst through a
reaction known as transesterification, is mainly produced in European countries and its total
production in 2005 was about 2.5 Mtoe (GBEP 2007). The production of biogas is diffused in
all the countries, and in the last few years it has been strong implemented in countries with
high feed in tariffs for electricity generation from biogas (especially European countries). In
some countries (such as Germany and Sweden), biogas is also used as transportation biofuel,
after upgrading to biomethane. For instance, Sweden currently leads the world in automotive
biogas production, with a total fleet of approximately 4500 vehicles with 45 % of its fuel
supplied by biomethane (Jönsson and Persson, 2003).
Already commercially available biobased products include adhesives, cleaning compounds,
detergents, dielectric fluids, dyes, hydraulic fluids, inks, lubricants, packaging materials, paints
and coatings, paper and box board, plastic fillers, polymers, solvents, and sorbents.
However, most of these biofuels and biochemicals are produced in single production
chains and not with a biorefinery approach, and have raw materials in competition with the
food and feed industry. Their exploitation is thereby limited. An alternative can be
represented by lignocellulosic materials. In fact, lignocellulosic feedstocks can be supplied
either from dedicated crops or as residues from agricultural, forestry and wood industry. This
feedstock is made of 3 main components (cellulose, hemicellulose and lignin) which can be
refined into different final products using a set of jointly applied technological processes.
There is not anymore a competition with the food and feed industry since lignocellulosic
biomass can be grown on land which is not suitable for agricultural crops. Moreover, in
comparison with conventional starch and oilseed crops that can contribute only with a small
fraction (grains and seeds) of the above standing biomass to bioenergy and biochemical
