Insights into Algae Biorefinery

High oil prices, competing demands between foods and other biofuel sources, and the world food crisis, have ignited interest in algaculture (farming of algae) for making vegetable oil, biodiesel, bioethanol, biogasoline, biomethanol, biobutanol and other biofuels. Algae can be efficiently grown on land that is not suitable for agriculture and hold huge potential to provide a non-food, high-yield source of biodiesel, ethanol and hydrogen fuels.

Several recent studies have pointed out that biofuel from microalgae has the potential to become a renewable, cost-effective alternative for fossil fuel with reduced impact on the environment and the world supply of staple foods, such as wheat, maize and sugar.

What are Algae?

Algae are unicellular microorganisms, capable of photosynthesis. They are one of the world’s oldest forms of life, and it is strongly believed that fossil oil was largely formed by ancient microalgae. Microalgae (or microscopic algae) are considered as a potential oleo-feedstock, as they produce lipids through photosynthesis, i.e. using only carbon , water, sunlight, phosphates, nitrates and other (oligo) elements that can be found in residual waters. Oils produced by diverse algae strains range in composition. For the most part are like vegetable oils, though some are chemically similar to the hydrocarbons in petroleum.

Advantages of Algae

Apart from lipids, algae also produce proteins, isoprenoids and polysaccharides. Some strains of algae ferment sugars to produce alcohols, under the right growing conditions. Their biomass can be processed to different sorts of chemicals and polymers (Polysaccharides, enzymes, pigments and minerals), biofuels (e.g. biodiesel, alkanes and alcohols), food and animal feed (PUFA, vitamins, etc.) as well as bioactive compounds (antibiotics, antioxidant and metabolites) through down-processing technology such as transesterification, pyrolysis and continuous catalysis using microspheres.

Algae can be grown on non-arable land (including deserts), most of them do not require fresh water, and their nutritional value is high. Extensive R&D is underway on algae as raw material worldwide, especially in North America and Europe with a high number of start-up companies developing different options.

Most scientific literature suggests an oil production potential of around 25-50 ton per hectare per year for relevant algae species. Microalgae contain, amongst other biochemical, neutral lipids (tri-, di-, monoglycerides free fatty acids), polar lipids (glycolipids, phospholipids), wax esters, sterols and pigments. The total lipid content in microalgae varies from 1 to 90 % of dry weight, depending on species, strain and growth conditions.

Algae-based Biorefinery

In order to develop a more sustainable and economically feasible process, all biomass components (e.g. proteins, lipids, carbohydrates) should be used and therefore biorefining of microalgae is very important for the selective separation and use of the functional biomass components.

The term biorefinery was coined to describe the production of a wide range of chemicals and bio-fuels from biomass by the integration of bio-processing and appropriate low environmental impact chemical technologies in a cost-effective and environmentally sustainable. If biorefining of microalgae is applied, lipids should be fractionated into lipids for biodiesel, lipids as a feedstock for the chemical industry and essential fatty acids, proteins and carbohydrates for food, feed and bulk chemicals, and the oxygen produced can be recovered as well.

The potential for commercial algae production, also known as algaculture, is expected to come from growth in translucent tubes or containers called photo bioreactors or in open systems (e.g. raceways) particularly for industrial mass cultivation or more recently through a hybrid approach combining closed-system pre-cultivation with a subsequent open-system. Major advantages of a algal biorefinery include:

  • Use of industrial refusals as inputs ( CO2,wastewater and desalination plant rejects)
  • Large product basket with energy-derived (biodiesel, methane, ethanol and hydrogen) and non-energy derived (nutraceutical, fertilizers, animal feed and other bulk chemicals) products.
  • Not competing with food production (non-arable land and no freshwater requirements)
  • Better growth yield and lipid content than crops.

Indeed, after oil extraction the resulting algal biomass can be processed into ethanol, methane, livestock feed, used as organic fertilizer due to its high N:P ratio, or simply burned for energy cogeneration (electricity and heat). If, in addition, production of algae is done on residual nutrient feedstock and CO2, and production of microalgae is done on large scale in order to lower production costs, production of bulk chemicals and fuels from microalgae will become economically, environmentally and ethically extremely attractive.

Prospects of Algae Biofuels in Middle East

Algae biofuels have the potential to become a renewable, cost-effective alternative for fossil fuels with reduced impact on the environment. Algae hold tremendous potential to provide a non-food, high-yield, non-arable land use source of renewable fuels like biodiesel, bioethanol, hydrogen etc. Microalgae are considered as a potential oleo-feedstock, as they produce lipids through photosynthesis, i.e. using only CO2, water, sunlight, phosphates, nitrates and other (oligo) elements that can be found in residual waters.

Algae also produce proteins, isoprenoids and polysaccharides. Some strains of algae ferment sugars to produce alcohols, under the right growing conditions. Their biomass can be processed to different sorts of chemicals and polymers (Polysaccharides, enzymes, pigments and minerals), biofuels (e.g. biodiesel, alkanes and alcohols), food and animal feed (PUFA, vitamins, etc.) as well as bioactive compounds (antibiotics, antioxidant and metabolites) through down-processing technology such as transesterification, pyrolysis and continuous catalysis using microspheres.

Microalgae are the fastest growing photosynthesizing organism capable of completing an entire growing cycle every few days. Up to 50% of algae’s weight is comprised of oil, compared with, for example, oil palm which yields just about 20% of its weight in oil. Algae can be grown on non-arable land (including deserts), most of them do not require fresh water, and their nutritional value is high. Extensive R&D efforts are underway worldwide, especially in North America and Europe, with a high number of start-up companies developing different options for commercializing algae farming.

Prospects of Algae Biofuels in the Middle East

The demand for fossil fuels is growing continuously all around the world and the Middle East is not an exception. The domestic consumption of energy in the Middle East is increasing at an astonishing rate, e.g. Saudi Arabia’s consumption of oil and gas rose by about 5.9 percent over the past five years while electricity demand is witnessing annual growth rate of 8 percent. Although Middle Eastern countries are world’s leading producers of fossil fuels, several cleantech initiatives have been launched in last few years which shows the commitment of regional countries in exploiting renewable sources of energy.

Algae biofuels is an attractive proposition for Middle East countries to offset the environmental impact of the oil and gas industry. The region is highly suitable for mass production of algae because of the following reasons:

  • Presence of large tracts of non-arable lands and extensive coastline.
  • Presence of numerous oil refineries and power plants (as points of CO2 capture) and desalination plants (for salt reuse).
  • Extremely favorable climatic conditions (highest annual solar irradiance).
  • Presence of a large number of sewage and wastewater treatment plants.
  • Existence of highly lipid productive microalgae species in coastal waters.

These factors makes it imperative on Middle East nations to develop a robust Research, Development and Market Deployment plan for a comprehensive microalgal biomass-based biorefinery approach for bio-product synthesis. An integrated and gradual appreciation of technical, economic, social and environmental issues should be considered for a successful implementation of the microalgae-based oleo-feedstock (MBOFs) industry in the region.