2.1.5 Commercial Microalgae Cultivation in Raceway Ponds
The commercialization of biofuel from microalgae is still in its early gestation and
has lot of challenges to achieve cost-competitive fuels. Currently, the industrial
microalgae biomass production is restricted to high value.
Raceway ponds are under operation worldwide to produce a diverse range of
products. For example, Cyanotech Corporation, in Hawaii, has cultivations in
raceways of Spirulina platensis and Haematococcus pluvialis, to produce Spirulina
Pacifica
® and BioAstin
® Natural Astaxanthin, respectively. Nikken Sohonsha
Corporation (Japan) produces more than 40 different products (healthcare products,
medical products, cosmetics, dietary supplements, fertilizers, and animal feeds)
from microalgae as Chlorella, Dunaliella, Monodus, and Isochlysis. Tianjin
Norland Biotech (China) cultivates Spirulina, Chlorella, and H. pluvialis to produce Spirulina tablets, Chlorella tablets, astaxanthin, astaxanthin oil, and
phycocyanin.
However, it is important to point out that many companies are working with
pilot plant tests for biofuels production. Examples of companies that are using open
systems in their tests are the LiveFuels (USA), OriginOil Inc. (USA), PatroSun
(USA), Neste Oil (FI), Ingrepo (NL), and Aquaflow Bionomics (NZ) (Su et al.
2017a, b).
2.2 Tubular Photobioreactor
Recently, closed PBRs, especially tubular photobioreactors have been successfully
used for commercial microalgal biomass production. Unlike open raceways, tubular
photobioreactors permit a good control of culture conditions and high solar radiation availability and, consequently, a high biomass productivity, which makes this
type of system potential for biofuel production and compounds of high commercial
value (Kunjapur and Eldridge 2010; Abomohra et al. 2016).
A tubular photobioreactor consists of an array of straight transparent tubes that
are usually made of plastic or glass and have a diameter of 0.1 m or less. These
transparent tubes can be arranged in different patterns (e.g., straight, bent, or spiral)
and orientations (e.g., horizontal, inclined, vertical, or helical) in order to maximize
the sunlight capture (Huang et al. 2017). However, to increase the scale, the tubes
are usually arrayed in a horizontal fence-like, which improves the land utilization,
and also have a better angle for incident light (Junying et al. 2013).
Besides the solar array for algae growth, a tubular photobioreactor is also
composed of a harvesting unit to separate algae from the suspension, a degassing
column for gas exchange and cooling (heating) and a circulation pump (Wang et al.
2012). The microalgal culture flows through solar collector tubing and is recirculated by maintaining highly turbulent flow, which is produced using either a
mechanical pump or a gentler airlift pump (Abomohra et al. 2016; Chang et al.
2017).
2 Microalgal Production Systems with Highlights …
11
The commercialization of biofuel from microalgae is still in its early gestation and
has lot of challenges to achieve cost-competitive fuels. Currently, the industrial
microalgae biomass production is restricted to high value.
Raceway ponds are under operation worldwide to produce a diverse range of
products. For example, Cyanotech Corporation, in Hawaii, has cultivations in
raceways of Spirulina platensis and Haematococcus pluvialis, to produce Spirulina
Pacifica
® and BioAstin
® Natural Astaxanthin, respectively. Nikken Sohonsha
Corporation (Japan) produces more than 40 different products (healthcare products,
medical products, cosmetics, dietary supplements, fertilizers, and animal feeds)
from microalgae as Chlorella, Dunaliella, Monodus, and Isochlysis. Tianjin
Norland Biotech (China) cultivates Spirulina, Chlorella, and H. pluvialis to produce Spirulina tablets, Chlorella tablets, astaxanthin, astaxanthin oil, and
phycocyanin.
However, it is important to point out that many companies are working with
pilot plant tests for biofuels production. Examples of companies that are using open
systems in their tests are the LiveFuels (USA), OriginOil Inc. (USA), PatroSun
(USA), Neste Oil (FI), Ingrepo (NL), and Aquaflow Bionomics (NZ) (Su et al.
2017a, b).
2.2 Tubular Photobioreactor
Recently, closed PBRs, especially tubular photobioreactors have been successfully
used for commercial microalgal biomass production. Unlike open raceways, tubular
photobioreactors permit a good control of culture conditions and high solar radiation availability and, consequently, a high biomass productivity, which makes this
type of system potential for biofuel production and compounds of high commercial
value (Kunjapur and Eldridge 2010; Abomohra et al. 2016).
A tubular photobioreactor consists of an array of straight transparent tubes that
are usually made of plastic or glass and have a diameter of 0.1 m or less. These
transparent tubes can be arranged in different patterns (e.g., straight, bent, or spiral)
and orientations (e.g., horizontal, inclined, vertical, or helical) in order to maximize
the sunlight capture (Huang et al. 2017). However, to increase the scale, the tubes
are usually arrayed in a horizontal fence-like, which improves the land utilization,
and also have a better angle for incident light (Junying et al. 2013).
Besides the solar array for algae growth, a tubular photobioreactor is also
composed of a harvesting unit to separate algae from the suspension, a degassing
column for gas exchange and cooling (heating) and a circulation pump (Wang et al.
2012). The microalgal culture flows through solar collector tubing and is recirculated by maintaining highly turbulent flow, which is produced using either a
mechanical pump or a gentler airlift pump (Abomohra et al. 2016; Chang et al.
2017).
2 Microalgal Production Systems with Highlights …
11