Low volumes and high production costs of algae appear to restrict it to ‘high value’ industries such as the supplement and nutraceutical sector.
According to Spanish-based AlgaeMax, a project led by technology solutions provider Atekena along with the European Union amongst others, the global algae biomass market in 2014 was worth between €3.5bn and 5bn.
With the health food sector worth €1.5bn and aquaculture applications accounting for €0.5bn, the potential for microalgae becoming a sustainable source of proteins, carbohydrates and oils production is all too real.
The challenge for the two main global markets, the EU and the USA, remain similar, with a large-scale commercial microalgae set-up that produces a workable cost-effective yield, to a specified quality proving elusive.
Compared to the European algae scene, the relatively optimal climatic conditions, coupled with low levels of rainfall, high levels of sun hours and intensity and high temperatures has proved advantageous to the US for algae production.
Closed photobioreactor systems
For the majority of larger algae producers, a closed system glass-tube photobioreactor (PBR) system remains a popular choice.
“Closed systems like ours prevents infiltration of the algae cultures from dozens of different unwanted organisms like foreign algae species, protozoa and amoeba,” explained Bob Capelli, executive vice president of Global Marketing at astaxanthin specialists Algae Health Sciences.
“These impurities can contaminate the purity of the algae and hinder astaxanthin production in the algae.”
According to Capelli, the advantage of using glass over plastic tubes is because “plastic can leach plasticizers into the algae when the sun's UV rays are hitting the tubes.”
Environmental considerations are also at the forefront of Californian-based Algae Health Sciences and its choice to use natural sunlight compared to other closed systems that remain indoors and use artificial light.
While PBRs result in a higher production efficiency, the benefits are offset by the higher purchasing and extraction costs of producing more valuable micro algae derived products such as astaxanthin, omega-3 fatty acids and β-carotene.
According to the European Commission, production volumes of poly-unsaturated fatty acids (DHA/EPA) from micro-algae are only 240 tons/year, but the market value of this production (mostly extracted from ocean fish) is estimated to be higher than €251.9m ($300m) a year.
“Producing in photobiorectors is certainly not cheap,”Capelli explained.“However, this system yields a highly pure, contaminant-free product.
“We've been able to attain unprecedented levels of astaxanthin in our algae biomass lots, we've found that our production cost is slightly lower than open-pond systems and certainly lower than indoor systems using artificial light.
“But there is still a long way to go before any of these systems can produce at cost levels low enough to justify inverting capital into the fuel-from-algae industry. To date, that concept is still a dream.”
Another European-based algae cultivator that has adopted the closed photobioreactor cultivation system is Algalif.
In keeping with the sustainability aspects of microalgae, the Icelandic supplier believe its very location contributes to the purity and quality of its product.
“Iceland provides the perfect starting point for our algae cultivation,” explained Andrew Jacobson, CEO of Algalif. “The country is an astoundingly pristine environment, free of contaminants and pollutants; access to abundant, pure water; and a continuous supply of renewable energy.
“We use a proprietary lighting system which enables us to reduce overall energy consumption by 50%, in addition to providing for optimal microalgae growth, productivity and yield.
“Moreover, our enclosed photobioreactor cultivation system reduces water use and allow us to grow algae at a much higher cell density than in other systems.”
Algalif uses the country's environmental advantages to the very maximum, harnessing its air quality, hydro and geothermal resources to help form a three-phase cultivation process.
The end product is an astaxanthin yield with extremely low levels of the toxic metals, arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg).
“The absolute need for purity is paramount in all algae-based production, as algae has notoriously high biosorption capacity for contaminants in water,” explained Dr Tryggvi Stefánsson, science manager at Algalif.
“Trace amounts of contamination in the water used for cultivation are, therefore, absorbed and accumulated in the algae. Astaxanthin production is especially vulnerable to these issues, due to the time it takes to accumulate the carotenoid.
“In order to harvest astaxanthin, Haematococcus must first be cultivated to an appreciable biomass, then astaxanthin accumulation can begin. Icelandic water has been vital to ensure the unparalleled astaxanthin purity, as the water is practically devoid of any contaminants.”
Algalif appear not to have any issues concerning scalability and ensuring a steady supply of astaxanthin.
“The scalability for enclosed PBR systems is modular,” said Dr Haraldur Gardarsson, Algalif’s quality control manager.
“Each photobioreactor system has a finite maximum volume. This is not due to contamination risks, however, but for optimum cultivation parameters.
“The scalability for astaxanthin therefore comes by adding more PBR systems to the production line. This modular scalability has the added benefit of increased quality control, and quicker response times, ensuring a steady production output.”
Open raceway pond systems
With the success of the PBR system, it would be easy to think that other solutions are not worth considering.
In Europe however, open raceway ponds are proving popular due to their ease of build and relative cost. This production method uses a paddle wheel to stir nutrients and microalgae whilst preventing sedimentation.
The continuous motion of the paddle wheel also avoids the formation of a temperature gradient, evenly distributes nutrients and carbon dioxide, for removal of produced oxygen and for transporting algae from and to the surface, which ensures the light available is fully utilised.
Like closed systems, raceway ponds are deemed suitable for the cultivation of certain micro-algae or cyanobacteria with Arthrospira platensis (Spirulina), and Dunaliella salina microalgae being the most important.
Examples of their use in Europe include the Netherlands, where raceway ponds are used by Kellstein Greencircle at Hallum and at the AlgaePARC, a pilot research facility of Wageningen University.
In Italy, Eni, a company based in Rome have been using raceway ponds to fix CO2 from a power plant, whilst in France, AlgoSource Technologies use raceway ponds in addition to PBR technology to produce spirulina.
“Spirulina is on one hand an interesting organism to grow because pH conditions required are extreme in order to avoid contaminants,” said Dr Jean-Michel Pommet, director of Innovation and Development at AlgoSource.
“However, open pond spirulina production doesn’t allow for purity and many sources of spirulina aren’t free of many other organisms,” he added.
Dr Pommet said that scaling up to commercial level was a problem for any process especially to cultivate photosynthetic microorganisms without using a fermentation process.
“Spirulina is capable of growth in raceway pond systems, which makes the scale up process easier. We apply the concept of "industrial ecology" which means that we produce our spirulina using heat for example from other industrial activity reducing a lot production cost.“
Closed fermentation technology
Dr Pommet touches upon another method of cultivating microalgae that uses closed, contained steel fermenters to produce heterotrophic algae.
Depending on the size, these fermenters are either placed indoor or outdoor and are mainly used for the production of long chain unsaturated fatty acids by the heterotrophic algae Crypthecodinium cohnii, Schyzochytrium or Ulkenia.
Heterotrophic algae can be cultivated in 75 000 - 100 000 litre fermenters and at high densities (30 – 100 grams per litre (g/l))
US-based TerraVia Holdings are one such company using this approach to growing microalgae.
According to its senior vice president food and ingredients Mark Brooks, the decision to use enclosed fermentation tanks was due to the degree of control offered as well as the purity and consistency.
“TerraVia’s algae ingredients are grown in contained fermenters, as opposed to an open environment, which ensures high quality, contamination-free ingredients.
“It provides the opportunity for microalgae to be produced in a diversity of geographies and seasons,” he explained.
“The algae can be fed a wide variety of renewable plant-based sugars, also known as feedstock flexible, and the potential feedstocks include sugarcane-based sucrose, corn-based dextrose, sugar beets, and green waste.
The algae then convert the sugar into oils, lipids, and proteins, which can be used in a variety of applications, such as food ingredients and cosmetics.”
Terravia’s production methods are well-suited to its offerings that include its omega-3 DHA algae oil AlgaPrime – the firm’s alternative to marine-derived sources of omega-3 fatty acids.
Terravia are joined by a growing number of producers in Europe and the USA, which have made headway in producing omega-3 EPA and DHA from micro-algae, to be used for dietary supplements or food ingredients. These include Canada-based Flora Health, Martek/DSM and Blue Biotech of Germany.
‘Future of algae products is bright’
There’s no one single way to grow algae at commercial scale. Currently, the approach taken seems to be based on where they are located and the desired end product.
As algae production methods are honed, its potential as a superfood, biofuel or nutritional powerhouse for the masses may finally be realised.
“Advances in manufacturing technology are enabling the industry to harness the power of algae at a commercial scale,” said Jacobson.
“For example, the successful cultivation of Haematococcus pluvialis in enclosed, indoor photobioreactors demonstrates that with adequate control of all parameters, microalgae can be cultivated in a productive manner. Therefore, we believe that the future of algae products is bright.”
“While we're still a long way off from cost-effective fuel production from algae, feeding the burgeoning world population and keeping them healthy using algae-based products is a realistic goal,” said Capelli.
“And as companies further refine their algae production methods, this goal may very well become reality over the coming years.”