Algae Crops: Coproduction of Algae Biofuels - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 367

potential of coproducing offshore wind energy in conjunction with the growth of
algae [ 11 ]. That study expanded upon work done by Buck and Buchholz [ 12 ],
Chynoweth [ 10 ], and P ´ rez [ 13 ].

Macroalgae

Macroalgae (seaweed) are multicellular plants growing in either salt or brackish
water. These plants are classified based on their pigmentation:

1. Brown seaweed (Phaeophyceae)
2. Red seaweed (Rhodophyceae)
3. Green seaweed (Chlorophyceae)

These types of seaweed are mainly used for the production of food and for the
extraction of hydrocolloids (e.g., agar, alginates, and carageenans) which are used
in the pharmaceutical and cosmetic industries. There are several species that are
suited for large-scale cultivation. These species require nutrients, salinity, temper-
ature, light depth, and currents [ 14 ]. Seaweed is used in production of food, feed,
chemicals, cosmetics, and pharmaceutical products, as well as wastewater
treatment.

Microalgae

Microalgae are microscopic photosynthetic organisms found in both freshwater and
saltwater. In general, these plants are very efficient at converting solar energy into
biomass. The most commonly used microalgae are Cyanophyceae (blue-green
algae), Chlorophyceae (green algae), Bacillariophyceae (which includes diatoms),
and Chrysophyceae (which includes golden algae) [ 14 ]. The main species of
microalgae used in commercial production include Isochrysis , Chaetoceros , Chlo-
rella , Arthrospira (Spirulina), and Dunaliella [ 15 ]. Currently, the size of the
microalgae production is less than 10,000 t a year.
Microalgae are used for food and feed in aquaculture. The therapeutic supple-
ments of microalgae include -carotene, astaxanthin, polyunsaturated fatty acid

such as DHA and EPA, and polysaccharides such as

β

-glucan [ 14 , 16 , 17 ]. The use
of microalgae for the generation of bioenergy, or the combined applications for
biofuels production and CO 2 -mitigation, such that CO 2 is captured and stored, has
been extensively researched [ 18 - 29 ].
Microalgae can be produced using photobioreactors. This technology uses
different types of tanks, tubes, bags, or other closed systems in which algae can
be cultivated [ 4 ]. There is a vast literature that reviews these alternatives (e.g., [ 30 ,
31 ]). Other technologies suggested in the literature, apart from shallow ponds,
include growing algae in conventional fermenters instead of photobioreactors

β