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They include both dedicated lignocellulose crops that can be grown for biomass produc-
tion such asMiscanthus, switchgrass, willow or poplar as well as lignocellulosic parts of
other crops like corn, wheat, rapeseed, sorghum and forestry residues such as wood-
chips or sawdust. Although the properties of lignocellulose differ from source to source
they can all be considered as difficult for conversion into other materials as well as their
individual components.
Aquatic feedstocks– These feedstocks include micro- and macroalgae. This group con-
tains a wide variety of chemicals within their structural and storage compounds; storage
materials of aquatic organisms can contain both carbohydrates (starch, glycogen, lami-
naran and others) and triglycerides. Algal cell walls do not pose similar recalcitrance as
lignocellulose do, but their composition makes the conversion challenging as many of
the compounds present in algal cell walls cannot be easily fermented by microorganisms
currently used in the industry.
In summary, biomass is composed of three major pools of chemicals: carbohydrates,
phenolics and triglycerides. These chemicals are distributed between different cel-
lular components: lignocellulose is a structural material composed of carbohydrates
and phenolics. Lignocellulose is robust and resistant to conversion. Plant storage
compounds contain both carbohydrates like sucrose and starch and triglycerides.
These storage compounds are more accessible for different conversion routes than
lignocellulose. The properties of these groups will determine their applicability for
various processes of biomass conversion.
3.4 Biomass Conversion Methods
Biomass conversion platform is usually understood as a set of related technologies that
could convert a feedstock (biomass of a certain characteristics) into products (array of
outputs from this process). Biomass conversion platforms are usually divided into ther-
mochemical and biochemical. The former is a thermal decomposition of biomass into
chemicals and energy, the latter utilisation of microorganisms to transform biomass
components into desired chemical compounds.
3.4.1 Conversion of Biochemical Energy Perspective
Various types of fuels have different functionalities and are therefore useful for var-
ious applications. Solid fuels like coal or wood can be stored relatively cheaply and
safely for prolonged periods of time but their combustion produces significant amounts
of particulate matter and ash that need to be appropriately disposed. Liquid fuels like
petroleum, diesel and biodiesel have high volumetric energy content and can be easily
transported through variety of routes such as pipelines or tankers. Gaseous fuels like
methane, propane or hydrogen have very high energy content by mass unit, but their
volumetric energy content largely depends on the pressure. Additionally, gaseous fuels
burn with much cleaner characteristics than solid or liquid fuels do but tend to be explo-
sive and need to be tightly controlled for any possible leakage. Each of these molecules
has its particular application either as a fuel or as a chemical feedstock, and its han-
dling depends on their particular properties. From the energy release point of view,
what matters most is the chemical composition and bond energies that are present in
