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Glass Tube Boosts Industrial Algae Yields

Tue, 10/29/2013 - 12:50pm
Dr. Nikolaos Katsikis, Director Business Development, Tubing, SCHOTT

Image: SCHOTTThe demand for algae is surging as researchers discover new applications for it across the food, pharmaceutical, nutraceutical, cosmetic and biofuel industries. Algae can be used as a nutritional supplement to add vitamins or healthy fats to food; as a producer of biologic and all-natural drugs; as an antioxidant in food supplements or rich oils in cosmetics and as the basis for clean fuels such as biodiesel.

It’s no surprise why algae is attracting so much attention. Algae cultivation doesn’t compete with agricultural land or production, and remains independent of raw material imports. It draws on sunlight as a main energy source and converts carbon dioxide into biomass and oxygen while it produces high concentrations of proteins, lipids, pigments and acids, and can be grown in salt water, freshwater or wastewater.

Algae is a versatile organism, and as a result, the industrial algae market has hit $1 billion and continues to grow. But despite algae’s potential, producing cost-effective yields for the many applications remains a problem. Few standards exist for industrial algae growth, and the calls for higher algae yields, greater efficiency and lower costs are resounding, especially in the biofuel industry. But a new glass tube photobioreactor could be the latest step toward these goals.

Improving algae yields
The pursuit of low-cost, clean and green biofuel has sparked interest in the industrial algae cultivation industry, drawing top manufacturers to invest millions of dollars in research and cultivation methods. Studies suggest that over the coming years, algae biofuel has the potential to make up one-twelfth of total U.S. fuel, but the industry struggles to cultivate consistent volume to reach this benchmark, leading researchers to seek solutions to improve current algae cultivation methods.

But while the cost of algae-based biofuels is still prohibitive, companies continue to develop algae-based cosmetics, fertilizers, medicines and nutraceuticals, further expanding the need for industrial-scale algae production that’s both efficient and cost effective.

Algae cultivation methods
Industrial algae production utilizes light energy to grow phototropic microorganisms, which build biomass through photosynthesis. Of the thousands of types of algae, some 100 to 200 can be industrially grown. Cultivating microorganisms is known as third-generation biomass, since the process occurs in relatively small areas and does not take up farmland to compete with food production.

Two main methods exist for industrial algae production: open ponds and photobioreactors (PBRs). Open ponds are low-depth, artificial ponds that are typically built in circular or raceway configurations and use paddle wheels or other mechanisms to keep the water in constant motion. Open ponds encourage algae growth through the constant addition of nutrients and carbon dioxide. While open ponds offer a seemingly inexpensive solution to algae production, they suffer from inherent drawbacks, such as space limitations, poor light utilization, water evaporation and pond contamination, all of which reduce yields. The disadvantages associated with open pond systems forced researchers to seek controllable solutions to algae production.

PBRs are closed-system, artificial algae growing environments that consist of rows of connected glass or plastic tubes typically between 5 and 30 cm in diameter. They provide a controlled and measureable process for consistent algae production. Closed systems allow for more precise control of ideal growing conditions by providing accurate monitoring of nutrients, pH and light to better enhance yields, while also increasing light distribution options via fiber optics or artificial light. PBRs enable researchers to grow sensitive genetically modified algae, which can only be cultivated in contained environments. Closed systems also enable researchers to easily move algae, adding greater flexibility with respect to production.

PBRs offer high yields and reproducible harvest results, positioning them as the future of the algae production industry. But while the solution offers a noticeable advantage over open ponds, the total algae production potential within PBR systems has yet to be tapped.

New photobioreactor could drive greater yields
One of the most recent innovations in the ongoing push for greater algae cultivation is the development of oval glass tubes for industrial algae growth in PBRs. Developed by SCHOTT, the tube’s oval shape is designed to diffuse light more evenly to aid the photosynthesis process and accelerate the growth of microorganisms to increase yields. The oval tubes are designed to support algae producers harvesting higher total yields through PBRs for high-value products or cultivators utilizing PBRs as quality seed reactors for the inoculation of open ponds.

The oval tubes are produced with borosilicate glass rather than polymer materials, making them resistant to ultraviolet light that can impede algae production. Glass is also scratch resistant and can withstand all cleaning agents to enable safe and reliable production over a long period of time. These new tubes come in a variety of different wall thicknesses, diameters and lengths to suit different facilities and applications.

The tubes could offer substantial cost-savings over traditional PBRs. The durable glass’ 20-year lifespan saves researchers from costly tube replacements and ensures sustained algae growth without technology failure. The tubes stretch from 1.4 to 10 m in length and, unlike polymer materials, require fewer support structures, reducing infrastructure costs. Finally, while the tubes are oval, their ends are perfectly round so that they can join with standard connectors to other glass or synthetic tubes, keeping costs low.

SCHOTT has already produced the oval tubes and is currently tracking algae growth in test installations comparing the performance of round and oval tubes in real test reactors supported by computer simulations. Based on the results, the company will continue to improve the tubes in order to ensure optimal light distribution and algae production.

Innovations that would increase the yield, efficiency and cost effectiveness of industrial algae growth would better support the myriad industries drawing on the attributes of algae to improve pharmaceutical production, cosmetics and food, as well as tear down one of the roadblocks to production of biofuels. In this drive, oval tubes could be the next big advance, offering a long-lasting, optimal environment for algae growth that limits costs while improving light diffusion, which could in turn drive higher yields and accelerate the industrial algae cultivation industry.  

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