Algae – a promising future food and biofuel

While algae may be a nuisance to some people, scientists and biotechnologists think otherwise. Algae have become increasingly popular as the future source of food and the next-generation biofuels. They are the fastest growing plant organisms in nature and capable of converting large amounts of carbon dioxide into oxygen. There are two broad categories of algae; macroalgae and microalgae.

Macroalgae are seaweeds, like kelp and sea lettuce; they are large, visible with the naked eye, and multicellular while microalgae are generally single-celled organisms that are microscopic. They tolerate a wide range of temperatures, salinities; pH values, light intensities, and grow individually or in symbiosis with other organisms. Like all plants, they are photosynthetic, utilize sunlight, capture carbon dioxide, and dissolve nutrients to produce biomass. Even in the absence of light, some algae species can be grown by utilizing organic carbon compounds such as sugar and starches. Their adaptability in various environmental conditions spiked the interest of several companies in the possibility of algae as a source of food and bioenergy.

Algae as Food Resources

Adding microalgae to food products would be a great strategy to enrich our diet in many nutrients and health beneficial components. The use of algae as food has been dated way back to 2500 years ago in some Chinese literature. Macroalgae are consumed in various parts of Asia, as well as native people of countries like Africa, South America, and Mexico due to their rich vitamins and nutritional value. A blue-green alga named Spirulina platensis is garnering global attention as a food additive due to its rich source of proteins, polyunsaturated fatty acids, pigments, vitamins, and phenolics. Currently, the microalgae market is ruled by Spirulina and Chlorella; often sold as tablets, capsules, and liquids to be used as dietary supplements.

 Several companies are now utilizing microalgae as an alternate protein source in health foods, according to a recent report by National Pharmaceutical Regulatory Agency (NPRA). One such company is TerraVia Holdings, which converts sugars into oils in closed fermentation tanks with the help of Chlorella microalgae at their site in Brazil. Their food product is currently being marketed under the name AlgaVia that offers sustainable, non-allergenic, vegan protein, and lipids in their microalgae powder for use in cooking, baking, and smoothies. Another company is SolixAlgredients, a Colorado-based company that is a well-known corporation in algae cultivation to bring products like Solasta ® Astaxanthin and Solmega® DHA omega-3, which are vegetarian, non-GMO dietary supplements.

Products like agar, alginates, and carrageenans are among the most valuable products that can be derived from algae due to their gelling and thickening properties. These ingredients are commonly used as an emulsifying and stabilizing agent in various foods such as jellies, jams, desserts, and meat products. Currently, the use of algae as aquaculture feeds is used extensively. The most commonly used algae for aquaculture feed are Chlorella, Tetraselmis, Pavlova, Phaeodactylum, Nannochloropsis, Skeletonema, and Thalassiosira. Hundreds of microalgae have been examined as food over the last few decades, but still, less than twenty have gained importance in the context of aquaculture.

Algae as Biofuel

The rapidly growing population of the world continuously increases the global demand for fuel energy. The intensive use of fossil fuels worldwide leads to its depletion and will bring them to the point of exhaustion due to its unsustainable nature. Thus, algae biofuel is now a growing opportunity throughout the world as an alternative to fossil fuels. The principles for making fuels from algae are simple:  Algae need water, sunlight, nutrients, and carbon dioxide to grow.  Algae thrive in shallow, dirty water, and they grow easily and quickly. They produce oil that can then be harvested and converted into biodiesel or other fuels.  Algae’s carbohydrate content can be fermented into ethanol.  Given the right conditions, algae can double its volume overnight. Research into algae for the mass‐production of oil is mainly focused on microalgae.  This is largely due to microalgae’s less complex structure, fast growth rate, and high oil content.

Unlike terrestrial crops such as corn and soybean, which require a full growing season to yield crops, algae can be harvested day after day.  Up to 50% of algae’s weight is comprised of oil, compared with, for example, oil‐palm trees which yield just about 20% of its weight in oil.  As a comparison, consider the yields of some of the dominant vegetable oil crops:  soybeans yield some 78 liters/hectare per year, canola 235 liters/hectare, and palm 1,000 liters/hectare per year. But, algae can produce some 16,000 liters/hectare per year, and possibly more.  It has been estimated, for example, that the U.S. could replace all of the diesel fuel currently used with an algae‐derived fuel using an area of land that is about one‐half of 1% of the current farmland now in use. Cultivation of algae will prevent further loss of habitat and environmental pollution, unlike other energy terrestrial crops. Besides, algae are also particularly engaging as a mean to curtail carbon emissions along with producing fuel as it consumes carbon dioxide and produces oxygen through photosynthesis. Furthermore, algae can be used to clean up waste by processing nitrogen from wastewater and carbon dioxide from power plants.  It can be grown on marginal lands that are useless for ordinary crops.

Given all the obvious attributes of algae as a feedstock for fuel, its production has yet to materialize in any meaningful volume.  The reason for this is centered upon the significant capital, operations, and maintenance costs to build and maintain the production and harvesting systems.  Algae are easily grown in small volumes but difficult to extrapolate into large‐scale production facilities.  The cheapest of all current technologies are still the open architecture approaches, for instance, ponds; which facing challenges with contamination, evaporation, temperature control, CO2 utilization, and general maintenance. The preferred approaches are the closed systems, generally known as photo-bioreactors, where algae remain in a closed environment to enable accelerated growth and better control over environmental conditions.  These glass or plastic enclosures can be mounted in a variety of horizontal or vertical configurations and can take many shapes and sizes. 

It is no doubt that microalgae show great potential for the sustainable production of food and fuel for the growing world population with increasing demands and changing habits. Since they are cultivated in technical systems, they do not contribute to massive land use, loss of biodiversity, and environmental pollution. Despite these advantages, the commercialization of algae technology in producing biofuel is still at an infant stage due to its high capital and maintenance cost. However, integrated food and fuel production is considered promising because the food market is more diversified and open to new and innovative products than the energy market. Integrated food and fuel production from microalgae will not only achieve higher returns on investment but also greater acceptance than fuel production alone.