Production of CO2 neutral transport fuels and bioplastics from
According to the Kyoto agreements the total CO2-emissions in the
industrialised nations need to be reduced by 5% in 2010 as compared to the 1990
level. In the longer term, a reduction of more than 50% is required to
stabilise the CO2-level in the atmosphere. A major strategy to
achieve these objectives is the large-scale substitution of petrochemical fuels
and products by CO2-neutral alternatives derived from biomass.
Large-scale application of the fermentation products bioethanol as a renewable
transport fuel and lactic acid in renewable packaging materials (polylactic
acid, PLA) can make a substantial contribution to this strategy.
Use of biomass as feedstock for bioethanol and lactic acid production
Bioethanol and lactic acid are currently produced by fermentation of sugars
derived from corn, sugar cane and sugar beet. The relatively high costs of
these agro-feedstocks form a major obstacle for large-scale application of
bioethanol and lactic acid. The use of lignocellulosic biomass and residues as
feedstock will increase the production volume and simultaneously reduce
production costs. This applies in particular for widely available, low-cost
residues from agriculture, agro-industry and forestry, and bio-wastes such as
the organic fraction of municipal waste and roadside grass. These biomass
streams are primarily composed of lignocellulose, a complex fibrous structure
of the sugar polymers cellulose and hemicellulose, which is strongly
intermeshed with the aromatic co-polymer lignin. Both the cellulose and
hemi-cellulose fractions are a potential source of fermentable sugars. For this
purpose the sugars must be released from the complex fibrous biomass by means
of physical/chemical and enzymatic methods. In the consecutive fermentation
process, the available sugars must be converted to bioethanol or lactic acid
with high efficiency. Non-fermentable residues from the process –mainly lignin–
can be used for thermal conversion generating power and heat for the production
process and surplus electricity for delivery to the grid. Bioethanol can be
applied in blends with fossil transport fuels, while lactic acid can serve as a
feedstock for production of polylactic acid (PLA) to replace petrochemical
packaging materials such as PET.
The industrial use of lignocellulose materials as a source of sugars for
fermentation processes still requires considerable R&D. The international
efforts in the past decades have thus far not resulted in a technology
applicable at industrial scale. In the Netherlands a 4-year R&D project
(2002-2007) is underway with the objective to develop technologies for the use
of lignocellulose as a raw material for bioethanol and lactic acid production.
The project –supported by the Economy, Ecology and
Technology Programme– is a co-operative effort of the industries
Purac biochem B.V., Royal Nedalco B.V.
and Shell Global Solutions International B.V.
and the R&D institutes ECN,
Agrotechnology & Food Innovations B.V.,
Wageningen University Dept. of Agrotechnology and Food Sciences,
TNO Environment, Energy and Process Innovation and
TNO Nutrition and Food Research.
The preparation of fermentable sugars from lignocellulose is a major challenge.
This requires integral optimisation of the trajectory from feedstock through
fermentation, as addressed in this project. Major R&D themes in the project
Physical/chemical pre-treatment for the mobilisation of (hemi)cellulose from
the lignocellulose matrix.
Optimisation of enzymatic cellulose hydrolysis with commercially available
Application of lignocellulose hydrolysates for ethanol and lactic acid
fermentation. Prevention of formation of inhibiting side products and
fermentation of C5 sugars are major issues.
Power and heat production from non-fermentable biomass fractions and process
integration with specific attention for optimal energy integration and
reduction of water use.
Application of bioethanol in blends with fossil fuels.
Economy and ecology
The European Commission has recently issued the “Concept Biofuels Directive” in
order to promote the substitution of fossil transport fuels by biofuels. The
objective is to reach a substitution level of 2% in 2005, 5.75% in 2010 and 8%
in 2020. If 25% of these EU targets are met through bioethanol this would imply
an additional market volume of 2,500 million Euro per year and a reduction of
CO2-emissions in the transportation sector by 18 Mtonnes/year.
Replacing petrochemical packaging materials (e.g. PET) and other chemicals
(such as solvents) by (poly)lactic acid could generate an additional EU market
volume of 760 million Euro/year and a CO2-reduction of approximately