Environmental Engineering Reference
In-Depth Information
Table 2.5 Productivity data of some macroalgae
Macroalgae
species
Biomass
yield
(t/ha/yr dry)
Location
System
Observations
Ulva sp.
22.5
Pennsylvania,
USA
Cultivated
Estimations based on
6 months' growth
Ulva sp.
45
Denmark
Cultivated
Extrapolation of
4-month trial
L. japonica
25
China
Cultivated
Commercially
achieved yield
L. japonica
60
Japan
Cultivated
Dry and ash-free value
L. hiperboria
30
Scotland
Natural
stock
Requires rest of
>
5 years between
harvests
Laminaria,
Gracilaria
multicrop
45
Southern
USA
Cultivation Optimized production
Red, green,
brown
multicrop
50
North Sea
Cultivation Theoretical yields
Source: Data compiled after Burton (2009).
intensified and, according to Wellinger (2009), research in this domain will
increase even further in the coming years and will switch from the purely
academic towards demonstration projects supported by power industries
interested in finding alternatives to rapidly decreasing oil reserves and
solutions for reduction of greenhouse gas emissions and carbon sequestra-
tion. Aquatic biomasses are feasible for wastewater remediation and
generate high biomass yields. Two groups are of interest for the biogas
sector. The first is represented by macroalgae, commonly referred to as
seaweeds, which are rich in natural sugars and other carbohydrates, are
known for their high biomass yields (Table 2.5) and have an important role
in supporting aquatic biodiversity.
The second group is microalgae - a heterogeneous group of microscopic
photosynthetic organisms, mostly unicellular, living in marine or fresh
waters. Of the over 30,000 species of microalgae known worldwide, only a
few are of actual commercial interest, including Chlorella, Spirulina,
Dunaliella and Haematococcus (Wellinger, 2009). Green microalgae,
known as diatoms, are considered the most suitable for energy and biogas
and other biofuels production, as well as for the production of high-value
materials. Microalgae have high photosynthetic efficiency and are rich in
lipids. One of the limitations of microalgae is their very low dry matter
content. In generating biodiesel for example, water needs to be removed to
allow bioesterification of
the lipids. The removal of water is energy
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