Algae Basics by Dr. Mark Edwards
CHAPTER 1: The Tiny Plant that Saved Our Planet
Algae saved our planet by transforming our atmosphere to oxygen, allowing life to exist. Algae saved us again by providing the Earth’s first food. Might algae save our planet yet again?
Early Earth supported neither living creatures nor food. About 3.7 billion years ago, no life existed because the Earth’s surface was too hot and there was no oxygen. The Earth’s atmosphere was composed of a blanket of deadly and heat trapping CO₂ and methane gas.
Fossil records show that a tiny plant emerged in the primordial soup and did an extraordinary thing. The plant absorbed the sun’s energy and used a chemical reaction, photosynthesis, to split a CO₂ and a water molecule. The tiny plant converted the carbon atom into a high-energy green plant bond, a hydrocarbon, by taking two hydrogen atoms from H₂O and released the oxygen molecule to the atmosphere. Algae had begun its work to change the atmosphere.
Abiogenesis, the study of how life on earth emerged, uses a primordial soup theory and suggests the chemical conditions on Earth created the essential building blocks of life. While debate continues on exactly how the first life was synthesized, fossils suggest the first plant cell, cyanobacteria, also known as blue-green algae, was the size of a nano-particle, 5 µ (microns). The period at the end of this sentence is about 500 µ.
Algae systematically collected solar energy, sequestered carbon atoms and released oxygen. Moving at the incredibly slow rate of one tiny molecule at a time, algae transformed the harsh carbon dioxide atmosphere that could not sustain life to an oxygen atmosphere that supported life. Algae took another 3 billion years to create sufficient oxygen to support other forms of life because land plants evolved from algae only about 500 million years ago.
Algae’s atmospheric transformation enabled the development of other water plants, fish, insects, land plants, amphibians, reptiles and eventually land animals. Even though microalgae are the tiniest plants on our planet, each day algae create 70% of the atmospheric oxygen, more than all the forest and fields combined.
Algae’s second gift — food
Algae’s contribution to our oxygen-rich atmosphere is matched by this tiny plant’s other gift — serving as the base of the food chain. Many of the earliest plants and water creatures depended on algae as a food source. Algae serve as nutritious food for everything from the tiniest phytoplankton to the largest mammal on earth, the great blue whale, because the plant offers an excellent set of proteins, minerals and vitamins. Every day, while algae captures CO₂ and releases pure oxygen, the green biomass supplies food for 100 times more organisms than any other food source on Earth.
The brutal conditions on Earth meant the first algae cells had to evolve and re-evolve millions of times as their microenvironments crashed with electrical storms and severe heat followed by freezes and meteor showers of super-heated rocks. Algae displayed incredible persistence and developed a wide variety of defense mechanisms that allowed the plants to survive and to propagate. Algae’s ability to adapt quickly in order to survive led to an estimated 10 million algal species, each with unique growth capabilities and biomass composition.
Since algae formed the lowest rung on the food chain, they developed a brilliant survival strategy — the ability to grow faster than its predators could eat. The herbivores that fed on algae ate many but not all of the fast growing plants. The ability to propagate faster than its predators could devour them created a tremendous competitive advantage and ensured algae’s survival. Algae may have been the first free lunch because many species developed the capacity to double their biomass before midday. A single algal cell may create a million offspring in a day.
Algae blooms were common in ancient oceans, lakes and ponds. The fossil fuels we burn today are made up mostly of fossilized algae. Children are taught in school that crude oil comes from dinosaurs but dinosaurs roamed the earth about 200 million years too late to become the biomass of choice for fossil fuels.
Most species of algae are so tiny they are visible only under a microscope. However, algae may group, bunch, cluster or grow in formations that are visible and edible. Algae typically are heavier than water and settle, creating a layer of green snow on the bottom of a pond. Algae’s green solar energy fuels growth for trillions of organisms daily as algae’s stored energy moves up the food chain.
Marine algae called seaweeds or macroalgae often grow into forms that have the appearance of land plants with pseudo roots, trunks and leaves. This parallel evolution enables marine algae to grow to sizes as large as trees. Macroalgae are often eaten directly by fish and mammals such as sea otters, manatees, dolphins and whales. Macroalgae provide a variety of bright colors for the oceans and far more biomass than herbivores can eat.
Algae grow in forests under the polar ice caps, in soils under glaciers, in the hottest and driest deserts as well as in pools, aquariums and water ways. Algae’s simplicity enables these plants to be incredibly robust; they not only survive but produce high-value biomass in extremely tough environments. The toughest environments existing on Earth today probably seem tame to a plant that survived the harsh environmental conditions billions of years ago.
Algae use plentiful and often surplus inputs, including sunshine, CO₂, and waste, brine or ocean water. Algae photosynthesis strips CO₂ and nutrients from the surrounding water and produces plant biomass made up of various forms of lipids (oils), protein and carbohydrates. The process releases considerable pure oxygen to the atmosphere.
Algae serve as a major food source for many organisms in natural settings with no human cultivation. Wild algae growing in natural settings produce incredibly fast biomass growth but are neither reliable nor sustainable because production typically crashes due to either nutrient limitation or predator attack. Cultivating algae in ponds, troughs or containers enables significant productivity improvements over wild algae because sufficient nutrients can be provided and predators managed or avoided.
The most common nutrient limitation in natural settings occurs from carbon, nitrogen or phosphorus. Inorganic nutrients, such as nitrogen, are available only to the degree that they are available as free ions, diluted in the water. However, algae can quickly consume the available ions in natural settings such as lagoons. Again, algae adapted strategically, and many species have the ability to consume organic nutrients from biological biomass or other waste.
Might algae save us again?
Humble algae saved our planet by sequestering two pounds of CO₂ in every pound of algal biomass. Today, our atmosphere and oceans carry massive amounts of CO₂ from human caused fossil fuel pollution. Algae may play a role in saving our planet again by reducing the atmospheric carbon load. Algae can also reduce greenhouse gases by producing carbon-neutral liquid transportation fuels that recycle atmospheric carbon while displacing fossil transportation fuels. Carbon neutral fuels are made with algae feedstock when the cultivation, harvest and refining energy comes from renewable sources such as solar, wind, waves, geothermal or algal oil.
Algal fuels offer a significant advantage in that they burn cleanly, without black soot particulates. The black soot pollution that causes lung disease, respiratory illness and cancer came from the fossilization of algae into crude oil, coal and shale over 400 million years. Algal fuels are produced in a matter of weeks and are not fossilized, so they burn clean similar to their land-based cousins — vegetable oil.
Algae promise to provide much-needed solutions for our increasingly hot, crowded, hungry and energy consumptive societies. The opportunity before us is to cultivate algae in a manner that engages people globally to produce sustainable and affordable food and energy for their family and community needs locally.
CHAPTER 2: What’s it all about Algae?
Algae’s value chain.
A lgae may be humanity’s best friend. Algae can provide sustainable and affordable food and fuel, as well as ecological and novel solutions. Any food, fibers or materials that can be made from land-based crops can be made from algae because land plants evolved from algae 500 million years ago. Algae offer a much wider array of colors, textures, tastes and compounds than land plants. Any fuels, plastics or other materials made from fossil fuels can be made from algae because fossil fuels are simply fossilized algae or the organisms that ate algae.
The most useful algal attribute is not that we can make just about anything from algae. What sets algae apart from terrestrial plants and fossil fuels is how the algal food, energy and co-products are made. Our atmosphere is overloaded with CO₂, which is naturally recycled or sequestered with algae production. Food crops will fail with global warming, but algae flourish in heat. Our world has insufficient cropland for food crops, yet algae can produce supplemental food and energy on non-cropland.
Globally, societies are experiencing a dearth of fresh water, yet algae flourish in waste, brine or ocean water. We have already passed peak oil and algae can provide liquid transportation fuels at a lower cost than mining crude oil. Farmers face a severe shortage of natural resources such as phosphorus that algae can recover, as well as recycle and reuse nutrients from animal and human waste streams.
Algal cultivation can produce valuable biomass using no or minimal fossil resources that compete with land-based food crops, and do not require fertile soils, fresh water, fossil fuels, fertilizers and fossil agricultural chemicals. Co-locating algae production on farms or municipal waste sites enable algae to transform these expensive waste streams from a cost to profit center that provides energy, animal feed and rich organic fertilizer. Co-locating algae production near carbon sources such as power or cement plants or breweries offers potential pollution solutions in addition to biomass production for biofuels and valuable co-products. While algae cleans air and water, the green biomass transforms CO₂ and waste nutrients to valuable sugars, proteins, lipids, carbohydrates and other organic compounds.
O ur current food and transportation systems are massively pollutive to air, soils and water. Algae can produce carbon neutral food and fuel with a positive ecological footprint. Our current fuels burn giving off dirty black soot particulates, but algae burn cleanly. Algal fuels are made in a few weeks and did not suffer 300 million years undergoing deep and dirty fossilization. Algal fuels burn cleanly because they are essentially vegetable oil.
Algae make fascinating research because according to the leading textbook Algae by James Graham, Lee Wilcox and Linda Graham, 10 million algal species are estimated to exist. Probably 90% of all their special compounds remain to be discovered, described and cultivated. Algae produce far more compounds than found in land plants or animals because there are so many more species of algae than other organisms. Algae benefit from over 3 billion more years of adaption and evolution than land plants and they have created ingenious survival strategies to maximize their growth and vitality and to repel predators.
Algal components are already integrated throughout our food, feed, cosmetics and medicines. A market basket test at Arizona State University found that nearly 70% of products consumers commonly buy at the supermarket contain algal components. Most people do not eat algae directly but enjoy the products made from algal components that include: algal flour in lieu of wheat, corn or soy flour; algal oils that are healthier and less fattening than corn oil, and algal nutrients such as Omega 3s.
Low calorie, delicious algal chocolate will enable consumers to have their cake and eat it without guilt from high calories. In addition to lower fat and higher nutrients than land based foods, research in Russia and Japan suggests that the algae may alter enzyme activity in the liver that controls the metabolism of fatty acids, resulting in lower levels of fat, cholesterol and triglycerides in the blood.
Chocolate Algae Cookie
Algae are uniquely positioned to provide a value chain of products and solutions for critical human needs. The value chain includes sustainable foods, fuels, ecological and novel solutions, represented in Algae’s Green Promise.
Algae’s Green Promise
- Food. Algae supply high-protein, low-fat, nutritious, healthy and delicious human foods. Algae provide more vitamins, minerals and nutrients than land plants and are a natural health food. Algae do not provide a full solution for malnutrition due to their few calories.
- Note: Algae’s food value will be suboptimal until solutions are found for a few key issues; making hard cell walls digestible and producing fewer nucleic acids. All other green promises await only macro and micro-scale cultivated algal production systems.
- Food ingredients. Algae components enhance about 70% of the products in modern supermarkets including dairy products, beer, soft drinks, jams, bakery products, soups, sauces, pie fillings, cakes, frostings, colorings, ulcer remedies, digestive aids, eye drops, dental creams, skin creams and shampoos.
- Fodder. Algae produce high-protein, low-cost, nutritious animal feed with numerous vitamins, minerals and nutrients. Replacing half the food grains fed to animals sold as U.S. exports would save 20 million acres of cropland and several trillion gallons of fresh water. Local algal production in villages would feed millions of animals and save 20 million acres a year of forests and grasslands from desertification due to animal forage.
- Fisheries. Algae provide high-protein; low-cost, nutritious fish feed, vitamins and nutrients. Algae can be grown in-situ, in the water with the fin fish and shell fish. Fish tend to grow faster and with more vitality on algae than land grains because fish eat algae in their natural habitat.
- Fuels — biodiesel. Algal oils pressed directly from algal biomass produce renewable and sustainable, high energy biofuel from sunshine, C02 and wastewater. Replacing U.S. ethanol production would take 2 million acres of desert, half of one Arizona county. Replacing corn with algae as a biofuel feedstock would save each year 40 million acres of cropland, 2 trillion gallons of water, 240 million tons of soil erosion and extensive water pollution.
- Fuels — jet fuel, ethanol and hydrogen. Algae can produce a variety of high energy liquid transportation fuels including gasoline. While refining generally requires more energy input than squeezing out algal oil, the U.S. is likely to have a surplus of ethanol refinery capacity. Algae can be refined in fossil fuel refineries into the same products made from fossil fuels because fossil fuels are simply fossilized algae.
- Fossil fuels. Replacing U.S. ethanol production also would save 7 billion gallons of fossil fuel used to produce ethanol. Moving 1/10th of U.S. agricultural production from dirty diesel to clean algal-diesel would clean the environment and save 20 billion gallons of fossil fuels annually. Even larger fossil fuel savings would accrue from using algal oils to substitute for a portion of the diesel used by trucks, trains, ships and planes.
- Fire — cooking. Black smoke from cooking fires and heating with wood, weeds and dung causes smoke death for 1.6 million and disability for 10 million mostly women and children every year. Clean-burning, high energy algal-oil can end smoke death and the many smoke disabilities. Substituting algal oil for wood, dung and agricultural materials will save a tremendous amount of labor from gathering firewood and allow forests to be replanted.
- Fresh water. Running wastewater through algaculture feeds the plants and cleans the water. Producing fuel, fodder or fertilizer using wastewater or brine water saves water that would otherwise be used for land-based crops. Replacing half of U.S. food exports with algaculture foods would save 30 million acres of cropland, 2 trillion gallons of water and 5 billion gallons of fossil fuel.
- Fresh air. Flueing smoke stack gasses through algaculture removes CO₂, nitric oxides, sulfur and heavy metals such as mercury from power plant or industrial plants, sequesters greenhouse gasses and cleans the air. Algae represent only a partial solution since the plant only grows with sunshine and power plants operate 24 hours a day. Some producers have reported success with grow lights for night production.
- Fertilizer. Nitrogen-fixing algae may provide high nitrogen fertilizers at very low cost in both production and energy inputs. The product is natural, supports organic food production and can provide cheap local fertilizer to subsistence farmers globally. The algal ash retains fertilizer value after being burned in cooking fires.
- Forests. High energy algal-oil fuel can end the need to denude forests and grasslands for cooking and heating fuel. Villagers may replant their forests with nut trees or legumes for food to offset the low calories provided by algal foods.
- Fabrics. Algal carbohydrates are similar to wood and may be made into textiles, paper and building materials. Algal paper and building materials save forests. Fabrics save cropland for food crops and provide warmth. Algae may be made into biodegradable plastics, biofuels or other refined products.
- Foreign Aid. American foreign aid provides subsidized U.S. food, undermines or destroys local food production because farmers cannot compete with U.S. subsidized food. Gifting food fails to address the root cause of hunger and poverty — local control over food resources and community engagement. Algaculture foreign aid would transfer knowledge and some start-up materials to grow algal foods, fuels, fodder, fertilizer and medicines locally.
- Famine and disaster relief. Algae, with its rich set of vitamins and minerals, activates the immune system and wards off starvation while providing fuel, fodder, fabrics, fertilizers and fine medicines. Disaster relief with local algaculture production may prevent community starvation for millions. Local algal production solves the critical problem of food distribution.
- Fine medicines. High-quality, affordable medicines, vaccines and pharmaceuticals may be made from algal co-products or grown in algae bioengineered to produce advanced compounds such as antibiotics, vitamins, nutraceuticals and vaccines. These compounds are grown today in land plants and animals so algae offer significantly faster and lower cost production. Designer algae grown locally in villages could save millions of lives by providing low cost vaccines or other medicines that need no packaging or distribution. Fine medicines, especially personalized drugs tailored to an individual, may offer more value than all other algal co-products combined.
Nature’s first food production system on Earth, algaculture, offers extraordinary benefits. Solutions to commercial and small-scale growing systems will ignite a green gold rush to produce high-value and affordable food, fuels, fodder, fertilizers and medicines from algae.
Algal food products can create an abundance of food and energy while reducing demand for food products that require extensive cropland, fresh water, fertilizers and fossil fuels. Food production that adds only oxygen to the atmosphere and does not pollute local ecosystems will provide a very positive net yield to the environment.
Adapted from: Green Solar Gardens: Algae’s Promise to end Hunger, 2009.
CHAPTER 3: Algae History and Politics
Nearly every human society that lived near an ocean, estuary or lake used algae for food, fodder for their animals, fertilizer for their fields and medicines for cuts, bruises and stomach ailments. Dried algae provided the first portable convenience food and probably served as wampum in trade, along with white shell beads. Archaeological evidence shows early Neanderthals around the Mediterranean ate algae along with shellfish.
Algae’s extraordinary productivity capability has been recognized as a potential solution for global hunger for over a century. Excitement for algae as a global food solution has bubbled up several times and each time has burst in ignoble fashion. In the 1890s, experts worried about Thomas Malthus’ prediction that population growth would outstrip food and recommended nontraditional food sources including yeast, fungi and algae.
A similar initiative came and went after World War I. Scientists continued their search for sustainable food sources. After the Second World War, over half the world’s population was impoverished and hungry and experts recommended non-conventional agriculture as a way out of the Malthusian trap. Algae emerged as the best available antidote and numerous pilot projects attempted algal production.
Researchers announced they were able to grow nutritious algae using inexpensive materials under controlled laboratory conditions in 1948. When grown in optimal conditions—sunny, warm, shallow ponds fed by simple CO₂—Chlorella converted around 20% of available solar energy into plant biomass containing over 50% protein when dried. Unlike most plants, Chlorella’s protein was complete with the 10 amino acids then considered essential and it was packed with calories, fat and vitamins.
The press became ebullient about algae’s potential and Colliers’ Magazine sketched a farm of the future where fat coils of glass pipe produced thousands of tons of protein in automated farms. Experts, not to be outdone by journalists, created plausible scenarios where algae would solve world food supplies with near zero cost.
Unfortunately, researchers tripped on Murphy’s Law and everything that could go wrong did. Instead of being robust, Chlorella turned out to be a very temperamental organism and simply stopped growing with small changes in temperature, density, light, pH and nutrients. The plant was so fragile that harvest with centrifuges damaged the biomass as did the heat necessary for demoisturizing. Chlorella’s hard cell walls made it indigestible, which added the cost and energy of heat or additional mechanical processing.
While most researchers gave up on their quest to solve world hunger with algae, NASA investigated the use of algae in the 1950s as a way to feed astronauts during long spaceflights. In what has been called the “Algae Race,” Soviet and American projects competed to develop a self-contained aerospace life-support system that would use algae to convert astronauts’ waste into clean air, water and perhaps food. Scientists were unable to solve the contamination and weight problems and the program was scrapped.
As part of this effort, at least one research paper was published in 1961 in the Journal of Nutrition titled “Algae Feeding in Humans.” It sums up the sparse research on algae as a human food. The U.S. Army research team examined Chlorella from Japan that was grown in ponds, harvested, centrifuged, washed, heated and vacuum dried to a green powder. Their analysis showed the composition to be: protein: 59%, fat (oils): 19%, carbohydrates: 13%, moisture: 3% and ash: 6%.
The authors found that algal food supplements of up to 100 grams per day were tolerated by their five human subjects. The green algae used, Chlorella, gave a strong spinach-like flavor to the food supplemented. The most acceptable preparations were cookies, chocolate cake, gingerbread and cold milk. Larger supplements created stomach problems but symptoms disappeared after the supplements were discontinued. The team concluded that dried algae can be tolerated as a food supplement but further processing would be necessary before it could become a major food source. These findings relegated algae to a small sector of the health foods market. American research on algae as a food source practically evaporated.
Fortunately for mankind, the Green Revolution began in the 1950s and algal foods flourished again due to three nearly equally contributing factors:
- The invention of stronger pumps for irrigation
- New technologies for making synthetic fertilizers
- Advances in molecular genetics which created high-yield seeds
Stronger pumps and bigger pipes enabled farmers to heavily over-draft groundwater for irrigation. Farmers also piled more fertilizers, pesticides and herbicides onto their fields. The Green Revolution had begun and food grain yields doubled on an eroding foundation of cheap fossil fuels and fresh water.
Non-agricultural sources of food were unnecessary due to advances in food grain production. Consumers became conditioned by science fiction, journalists and movies to distrust non-traditional food sources.
Science fiction authors both popularized the concept of synthetic foods and anticipated unfavorable consumer reactions and unintended consequences such as the Killer Tomato and Frankenfoods. H.G. Wells’ The Time Machine, 1895, War of the Worlds, 1898, and The Food of the Gods, 1905, Aldus Huxley’s Brave New World, 1932 and Ward Moore’s Greener than You Think, 1947, all warned against biotechnological panaceas.
Harry Harrison’s Make Room! Make Room! in 1966 and Paul Ehrlich’s Population Bomb, in 1968 explicated the horrific outcomes of unrestricted population growth. Harrison’s apocalyptic scenario included plankton, yeast and algae as base foods for the starving masses. Chlorella had a fishy taste so marketers decided to produce an improved version they branded as Soylent Green. This led to the 1973 film adaption of Harrison’s book, Soylent Green, which suggests the algal biomass culture use not only human waste but recycled humans. Even with cannibalism, the invention could not feed everyone. Water and fertilizer shortages, plague, pestilence and pesticide poisonings ruined crops and polluted water. The greenhouse effect intensified, increasing flooding, violent storms and drought. Art indeed imitated life.
A remake of Soylent Green would set the algal industry back at least a decade. While science fiction authors were spurring public fears of Frankenfoods, people were experiencing green slime first hand in their aquariums, pools and recreational waterways. The press was eager to convey the sensational perils of algae that created deadly toxins, killer red tides and dead zones which killed many living organisms.
President Jimmy Carter initiated several algal projects to move the U.S. towards energy independence but the focus became shifting electrical grid production from oil to coal. The last remnant of Carter’s algal research, the 18-year Aquatic Species Program, was terminated by the Clinton administration as they made the political decision to shift government R&D from algal biofuels to corn ethanol. The unfortunate result of this policy was that universities and their faculty were not able to receive funded grants to study algae for over a decade.
Algae research received a knock-out blow in the 1990s when Congress ignored science and bet the U.S. biofuel future on corn ethanol. Corn received subsidies and incentives in a wave of greenwashing promises that ethanol would be sustainable, renewable, clean and displace oil imports. Existing research showed corn ethanol to be the opposite of these claims. Each acre of corn production erodes six tons of soil, pollutes groundwater and releases 2.5 tons of CO₂ plus nitric oxides, particulates and smog. The 9 billion gallons of ethanol produced in 2008 offset less than 3% of U.S. oil imports at the cost of billions in subsidies and environmental pollution. The Energy Policy Act of 2005 set a renewable fuels standard mandating more renewable production but left algae feedstocks out of the renewable energy policy.
Algae reappeared as a biofuel solution in 2008 as two industry associations emerged followed by an industry trade journal, Algae Industry Magazine. The first industry meetings of the Algal Biomass Organization and the National Algae Association in 2007 attracted a small number of scientists and a few biofuel entrepreneurs. The 2009 Algal Biomass Organization Summit in San Diego attracted over 800 and received international press coverage.
The politics of algae face a challenging future because algae must compete economically as well as ecologically with other green energy solutions. Other renewable energy solutions produce electricity but not gasoline, diesel or jet fuel. Algae stands alone as the viable solution for the move towards energy independence with liquid transportation fuels necessary for ships, planes, trucks and planes for the next 50 years.
CHAPTER 4: What are Algae’s Competitive Advantages?
Nano-sized, single-celled algae are among Earth’s earliest life forms. They have been surviving in many of Earth’s harshest environments for 3.7 billion years. Algae’s simplicity enables these plants to be incredibly robust—they not only survive but produce high-value biomass in tough environments. In good cultivation conditions, algae produce protein and energy biomass with yields that are 30 to 100 times more productive per acre than land plants.
Algae are critical to life on Earth as they produce the organic matter at the base of the food chain. The biomass is eaten by everything from the tiniest krill to the great blue whales. Algae also produce most of the oxygen needed for other aquatic life and provide about 70% of our daily atmospheric oxygen.
Algae, the Latin name for seaweed, present themselves in all shapes and sizes. Microalgae are single-celled, microscopic organisms often smaller than 5µ (microns) wide. The period at the end of this sentence is about 100µ.
Algae grow all over the Earth, including under both ice caps. Their preferred environments are in damp places or water but algae are common on land as well as in aquatic environments. Soils, rocks, trees and ice contain dried algae cells and many are still viable. Various algae species grow in all kinds of water, which makes them excellent for pollution control.
Seaweeds make up about 10% of algae and there are larger species that live in marine environments such as kelp: brown seaweeds that may grow to 180 feet. Seaweeds may appear to have trunks and leaves similar to land plants but these structures are actually undifferentiated cells called pseudo-leaves. In tropical regions, coralline algae help build corals and support the formation of coral reefs and other species that live in symbiosis with sponges.
Away from the oceans, most algae live not in waterways, but in soils. Algae live symbiotically in the roots of land plants where they break down soil compounds and make the nutrients bio-available to the plants. The blue-green algae, also known as cyanobacteria, also serve crops by fixing nitrogen from the atmosphere in root nodules or directly on plant surfaces. Many plains, mountains and deserts are covered with algal crusts that hold soil in place, provide a foundation for plants with roots and hold critical soil moisture. Algae bioengineer building materials such as limestone, which is the material the Egyptians used to build the Great Pyramids.
Various algae maximize different components. Some species offer over 50% lipids (oil), others 60% protein and others 90% carbohydrates. The food product, protein, of some species has little natural smell or taste so the product may take on the characteristics desired such as any smell, color, texture, density or taste. Blind taste tests between algae and soybeans favor algae because algae do not have the bitter, starchy taste of unprocessed soy. Like food grains, algae biomass benefits from food processing to maximize taste, texture, color and mouth appeal.
Algae are very efficient at converting light, water and carbon into biomass containing oily compounds (lipids) that may be extracted and processed into gasoline, green diesel or jet fuel. The remaining biomass, mostly protein and carbohydrate, may be made into foods, medicines, vaccines, minerals, animal feed, fertilizers, pigments, salad dressings, ice cream, puddings, laxatives and skin creams. An example of algae composition shows an algal species where 40% of the plant biomass is oil.
Fat algae, also called oleaginous algae, are species that produce large quantities of lipids. Green algae may not look like a biocrude oil feedstock but the petroleum used in today’s vehicles is derived from prehistoric biomass that came largely from algae blooms in ancient wetlands and oceans.
Nature’s biomass decomposition began over 200 million years ago in the Carboniferous Period under conditions of enormous heat and pressure. Oil pumped from the North Sea consists of decomposed haptophyte algae called coccolithophorids. Algae also make up the major components of diatomaceous Earth, coal shale and coal. The Egyptians built their pyramids with limestone formed from algae.
The 30-100 times annual yield per acre productivity advantage for algae occurs largely due to the differences between terrestrial and water-based plants. Algae express themselves in a nearly limitless number of species and strains, which makes them a unique organism. Several key characteristics differentiate algae from terrestrial plants.
Algae are water-based organisms that grow in fresh, saline, brackish, seawater or wastewater. Land plants require fresh water for growth because large salt ions clog their plumbing, root system, starving the plant of water and nutrients. Algae flourish in saline water because they evolved in very salty ancient oceans. Salt ions pose no problem for algae because algae have no roots.
Algae developed critical growth, propagation and survival strategies in their several billion of years on Earth. Land plants evolved from algae only 500 million years ago and require an entire growing season, 120-140 days to produce seeds for a new generation. In the time land plants grow through one generation, algae may propagate through millions of generations because algae have no growing season. Algae are different from land plants in many ways.
Algae’s Competitive Advantages
- Superstructure. Land plants invest a large portion of their energy in building cellulosic structure, including trunk, leaves and stems to withstand wind and weather. Algae have no such requirement. Water support algae like a natural womb.
- Sex. Land plants invest 35% of their energy in building and supporting their sexual apparatus. Algae are simple, single-celled organisms that do not have to bother with sexual structures. When conditions are good, algae propagate sexually. When a stressor arises, the cells can proliferate asexually.
- Roots. Land plants invest 25% of their energy in roots which lock them in place and make the plants dependent on in situ soil moisture and bio-available nutrients, typically provided by soil microbes such as algae. Algae have no roots and some species grow flagella, which they can wiggle to move to nutrients, moisture or solar energy.
- Growth speed. Land plants such as food grains require a full growing season from spring to fall — often 140 days or more to produce a single crop. Algae learned to flourish when nourished and can grow to maturity quickly. An alga cell may produce over a million offspring in a single day.
- Direction. Land plants grow slowly in one direction, towards the sun and may double their biomass in 10 days. Then they progressively slow growth to maturity. Algae grow in all directions, 360°, and may triple or quadruple its biomass daily.
- Continuous harvest. Algae grow so rapidly, half of the algal biomass may be harvested daily. Harvest may occur every day the sun shines, which may be 360 days a year in locations such as Arizona, New Mexico, Colorado and Texas.
- Continuous growing season. Some algal producers are growing algae year-round using species adapted for each season. Some producers use grow lights to augment solar energy. Several producers are experimenting with LED and other forms of light to extend growth beyond daylight hours.
- Robust production. A single event during an entire growing season such as temperature spike, drought, insects, wind or hail can devastate an entire food grain crop. When bad weather occurs, algae take a rest and slow down their growth rate or go into dormancy. When the weather improves, algae resume their rapid growth.
- Nitrogen fixation. Blue-green algae known as cyanobacteria are able to fix oxygen from the atmosphere, which promotes growth because nitrogen is often the limiting nutrient in stationary water.
- Composition. Land plant green biomass such as corn may be 80% non-oil or waste because most of the plant composition is cellulosic structure rather than protein for food or energy producing oils. Some strains of algae produce 50% lipids – oils that can be converted directly to jet fuels or green diesel.
- Stored energy. Land plants such as corn can be converted to ethanol that burns with less heat and provides only 64% of the MPG of gasoline. Algae convert sunshine, CO2 and other nutrients to long carbon chains that can be converted to more powerful liquid transportation fuels such as JP-8, jet fuel and green diesel that may have 30 to 50% more energy per gallon than gasoline.
- Energy positive. Ethanol production with corn is an energy sink because it consumes more energy, primarily diesel fuel and electricity, that the fuel delivers. Algae can produce fuels using minimal or no fossil fuel.
- Sustainable. Land crops consume massive amounts of fossil resources that will run out — fertile soil, fresh water, fossil fuels, fertilizers and fossil agricultural chemicals. Algae do not compete with land crops for resources and can grow with abundant resources that will not run out including sunshine, wastewater and surplus CO₂.
- Ecologically positive. Modern grain production adds 2.5 tons of CO₂ per acre plus nitric oxides, particulates and smog. Each crop acre erodes six tons of soil, which carries nutrient and chemicals that pollute wetlands, rivers and lakes. Algae cultivation emits only oxygen to the atmosphere while sequestering CO₂ and avoids soil erosion and ecosystem pollution.
- Geographical independence. Unlike land crops, numerous algal species grow in the harshest environments on Earth. In closed and semi-closed growing systems, algae can be grown in nearly any altitude, latitude, longitude or geography.
Algae are robust organisms that offer many advantages compared with land-based crops. Algae remain the most underdeveloped organism on Earth. Domesticating algae to gain its many benefits presents one of the most engaging challenges of the 21st century.
CHAPTER 5: Algal Classification
Algae are living plants that break the rules for plant classification because they evolved in many different forms — cells, multicellular plants, bacteria and in nearly infinite combinations. While the various species share certain characteristics, different algae, even of the same species, display extraordinary variety in shape, size, structure, composition and color.
A single algal species may change shape, composition and color in a single day based on culture variables such as available light energy, nutrients, temperature and acidity, pH. Similar to all living organisms, when algae are stressed, they switch to survival mode, which changes the speed and composition of cellular metabolism. Stressors may cause algae to store more oil at the expense of proteins or carbohydrates, to use for energy at a later time. Some algae seem to accumulate more oil in order to rise to the top of the water column where they can harvest more solar energy.
The classification of algae into taxonomic groups follows the same rules used for the classification of land plants. Land plant classification came before algae because many nano-sized algae species could not be seen prior to advanced microscopes. The major algal groups are distinguished on the basis of pigmentation, shape, structure, cell wall composition, flagella characteristics, products stored and method of propagation.
Algae display so many variations, even within each species, that they express exceptions to nearly every classification rule. Interestingly, many species can change the way they propagate based on ambient conditions. When conditions are good, they propagate sexually. When conditions degrade, they are able to use one or more asexual methods such as cell division, fragmentation or spores.
The ability to see minute differences in algal cells with the electron microscope has changed classifications substantially since the 1960s. Classification changes continue as new differentiators are discovered.
Algae are differentiated from other plants because they generally:
- Display the ability to perform photosynthesis with the production of molecular oxygen, which is associated with the presence of chlorophyll a, b or c;
- Do not have specialized transport tissues or organs consisting of interconnected cells that move nutrients and metabolites among different sites within the organism;
- Reproduce sexually or asexually to produce gametes that generally are not surrounded by protective multicellular parental tissue.
Land plants evolved from algae about 500 million years ago and evolved specialized cells for absorbing and moving nutrients and for reproduction. Algae are distinguished from the higher plants by a lack of true roots, stems or leaves. Some seaweed, such as kelp, appear to have leaves, but they are pseudo leaves made up of the same cellular structure as the rest of the plant. Scientists believe macroalgae — seaweeds — developed in parallel evolution with land plants.
Algal species culture collections are available at The University of Toronto, U.C. Berkeley, University of Texas, University of Copenhagen, the Scottish Marine institute, The Chinese Academy of Sciences , the University of Prague and the World Federation of Culture Collections. Most collections with provide composition and culturing information, culture sales, descriptive details and pictures. The excellent collection at the University of Texas offers a wide set of searchable parameters. The Algal Image Laboratory at Bowling Green provides digital images of algae at no charge for educational purposes.
Many species are single-celled and microscopic including phytoplankton and other microalgae while others are multicellular and may grow as tall as trees such as kelp. Phycology, the study of algae, includes the study of prokaryotic forms known as blue-green algae or cyanobacteria. Some algae also live in symbiosis with lichens, corals and sponges. The basic single-celled organism, algae, has the general appearance illustrated in the figure.
Eukaryotic green algae (Greek for “true nut”) plants are structured like a nut with a shell protecting their genetic material, which is arranged in organelles. Green algae create discrete structures with specific functions and have a double membrane-bound nucleus or nuclei. The prokaryotic cells of blue-green algae, cyanobacteria, contain no nucleus or other membrane-bound organelles.
Algae can be lively little critters even though they are not animals. Many can swim, such as dinoflagellates that have little whip-like structures called flagella, which pull or push them through the water. Some algae squish part of their body forward and crawl along solid surfaces. A few algae can even form eye buds that can detect light, which is critical for their energy supply.
Other species are made of fine filaments with cells joined from end to end. Some clump together to form colonies while others float independently. Seaweeds may grow in nearly any shape such as cones, tubes, filaments or circles. Algae form many more shapes than land plants and may change the shape or structure to adapt to local conditions. Major steps in cell complexity occurred with the evolutionary progression from a virus to bacterium and then from the prokaryotic cells of bacteria to the eukaryotic cells of algae. Cell walls enable algae to protect itself from the surrounding environment, typically water and pressure, called osmotic pressure.
Cell walls regulate osmotic pressure produced by water trying to flow in or out of the cell through its semi-permeable membranes due to a differential in the solution concentrations. Algae typically possess cell walls constructed of cellulose, glycoproteins and polysaccharides. Some species have a cell wall composed of silicic (silicon) or alginic acid.
Red algae, for example, are a large group of about 10,000 species of mostly multicellular, marine algae, including seaweed. These include coralline algae, which live symbiotically with corals, secrete calcium carbonate and play a major role in building coral reefs. Red algae such as dulse (Palmaria palmata) and laver (nori or gim) are a traditional part of European and Asian cuisine and are used to make other products such as agar, carrageenans and other food additives.
The broad algae classification includes:
- Bacillariophyta — diatoms
- Charophyta — stoneworts
- Chlorophyta — green algae
- Chrysophyta — golden algae
- Cyanobacteria — blue-green
- Dinophyta — dinoflagellates
- Phaeophyta — brown algae
- Rhodophyta — red algae
Green algae evolved with chloroplasts, which enables photosynthesis and greatly enhances available O₂. Blue-green algae have received most of the recent research because many scientists trained in bacteria research have begun studying the commercial value of this plant, classified as both a blue-green algae and bacteria; cyanobacteria.
Prochlorococcus, a blue-green algae may be the smallest organism on Earth, only 0.6 microns (millionths of a meter), but it is one of the most abundant organisms on the planet. A single drop of water may contain more than 100,000 of these single-celled organisms. Sallie Chisholm at MIT studies Prochlorococcus and says that trillions of these tiny cells make up invisible forests and provide about half the photosynthesis in the oceans.
|Taxonomic Group||Chlorophyll||Carotenoids||Storage products|
|Bacillariophyta||a, c||β-carotene, ± -carotene rarelyfucoxanthin||Chrysolaminarin oils|
|Chloro phycophyta (green algae)||a, b||β-carotene, ± -carotene rarely carotene and lycopene, lutein||Starch, oils|
|Chrysophycophyta (golden algae)||a, c||β-carotene, fucoxanthin||Chrysolaminarin oils|
|Cyanobacteria (blue green algae)||a, c||β-carotene, phycobilins|
|Phaeco phycophyta (brown algae)||a, c||β-carotene, ± fucoxanthin, violaxanthin||Laminarin, soluble carbohydrates, oils|
|Dinophyta (dinoflagellates)||a, c||β-carotene, peridinin, neoperididnin, dinoxanthin, neodinoxanthin.||Starch, oils|
|Rhodo phycophyta (red algae )||a, rarely d||β-carotene,zeaxanthin, ± β carotene||Floridean starch, oils|
The green often associated with algae comes from chlorophyll but algae also contain pigments of many colors, especially cyan, red, orange, yellow, blue and brown. Some varieties are colorless. Green algae appears green because green is the only color of light it does not absorb. Red algae absorb a full spectrum of colors and reflect red. Red algae can grow deeper in the oceans than most other species because they are equipped to absorb the blue light that penetrates deep in the ocean.
Algae use pigments to capture sunlight for photosynthesis but each pigment reacts with only a narrow range of the spectrum. Therefore, algae produce a variety of pigments of different colors to capture more of the sun’s energy. Algae channels light into chlorophyll a, which converts light energy into high-energy bonds of organic molecules.
Algae provide color to herbivores that feast on them. Algae give the greenish cast to the white fur of the well-known giant sloth. Algae live in the hollow hairs of polar bears and provide the pink pigment for flamingos, which they consume in both shrimp and algae. Similar algal carotenoids give the pink pigmentation to salmon.
Arizona’s Palo Verde nuclear power plant attracted a pink flamingo to its cooling ponds several years ago. The poor bird turned white and created worldwide press speculation about possible radiation leaks. Fortunately, a biologist figured out the ponds lacked sufficient beta-carotene in the algae to sustain the bird’s pink coloration. The flamingo flew to another pond with algae and quickly regained its pinkness.
Algae may grow in symbiosis with fungus to create lichen — the colorful rough material on the sunny side of rocks and trees. Algae and the fungus share a mutual dependence as the algae produces food for both plants and in exchange, gets water and minerals from the fungus. The fungus also provides critical protection against desiccation — drying and dying in the sun.
The use of algae-lichen plants for pigments and dyes pre-dates Julius Caesar. The classic red color of Roman tunics came from pigments extracted from lichens known as urchilles. Roman women valued the plant and used it as rouge to give their faces more color. Nearly all modern cosmetics contain algae components to improve color, emulsification and/or moisture retention.
CHAPTER 6: Algal Species Selection
Algae producers select specific algae strains for valuable compounds grown in the algal biomass. Algal biomass includes primarily lipids, used to produce biofuel, proteins for food, feed and nutraceuticals and starches and carbohydrates that can be made into a litany of products.
Lipids are long carbon chain molecules that store energy for the plant and serve as the structural components of cell membranes. Lipids are oils that make the plant more buoyant so that it moves up the water column towards solar energy. Some algal species are naturally very high in lipid production, e.g. 80% by dry weight, but they grow very slowly. Other species grow very fast and naturally store about 20% lipids but when stressed with nutrient limitation, store about 40% lipids.
Proteins are large organic compounds made of amino acids, arranged in a linear chain connected by peptide bonds. The plant’s genetic code determines the sequence of the amino acids but nutrient limitations may cause changes to the production of amino acids. Most proteins are enzymes that catalyze biochemical reactions and plant metabolism. Other proteins maintain cell shape and provide signaling functions within the plant.
Algae use photosynthesis and solar energy to produce glucose from carbon dioxide. The glucose is stored mainly in the form of starch granules, in plastids such as chloroplasts and amyloplasts. Algae can make water soluble glucose, plant sugar, but it consumes considerable space. Algae adapted the capability to make glucose in the form of starch, complex carbohydrates that are not soluble and store compactly. Starch is the most important carbohydrate in the human diet and algal carbohydrates can substitute for food grain flours such as corn, wheat, potatoes or rice. Starches may also be fermented into a wide variety of alcohols or biofuels.
The path forward based on the Aquatic Species Program and the experience of other research in algal production shows that robust algal species for biofuel production need the following properties:
- Produces high and constant lipid content.
- Grows continuously which requires overcoming the stability problem common to algae cultures.
- Demonstrates high photosynthetic efficiency.
- Grows with seasonal climatic differences and daily changes in temperatures.
- Creates minimal fouling from attachment to sides or bottom of containers.
- Easy to harvest and to extract lipids with soft or flexible cell walls.
Algal growers may select and buy species from culture collections available at the University of Texas, University of Toronto, U.C. Berkeley, University of Copenhagen, the Scottish Marine institute, The Chinese Academy of Sciences , the University of Prague and the World Federation of Culture Collections. Most collections with provide culture sales, composition and pictures. The Algae Gallery at the Smithsonian National Museum of Natural History includes considerable information on algae and links to algal sites.
The composition variation among species varies tremendously. Some algae hold 80% lipids while others produce 60% protein and still others are 92% carbohydrates. Species selection is critical not just for the desired composition but for a host of structure and growth variables that vary widely across species and strains.
When algae are nutrient limited, such as nitrogen, phosphorous or sulfur, they decrease production of essential polyunsaturated fatty acids and may yield lower quality protein with fewer amino acids. Nutrient deprivation may cause algae to increase lipid production but typically slows or halts propagation and growth. Bioengineers are working on algae that increase lipids without nutrient deprivation. Several research labs have created GM algal strains that secrete oil without harvest, enabling continuous production. Avoiding harvest and oil extraction eliminate huge time and cost factors.
Algal varieties offer an almost limitless combination of features. Special attributes are being enhanced through selection screens for naturally occurring organisms, bioengineering and hybridization. Algae experts like Drs. Milton Sommerfeld and Jerry Brand have invested many decades in searching wetlands, lakes and deserts for naturally occurring algae that demonstrate desirable properties. Dr. Bruce Rittmann has worked on genetically modifying algae to produce more oil or other advanced compounds. Many algal producers have worked to hybridize algal strains by cross fertilization in order to maximize desirable growth characteristics, ease of harvest and extraction and desirable compounds.
Each algal species offers a different proportion of lipids, starches and proteins, Table 1. Some algae are high in protein and others are mostly starches or lipids. Variations in culturing may substantially change algal biomass composition.
Table 1. Composition of Various Algae (% of dry matter)
Algal-oils are extremely high in unsaturated fatty acids and various algal-species provide:
- Linoleic acid, an unsaturated omega-6 fatty acid used for soaps, emulsifiers, quick-drying oils and a wide variety of beauty aids. The moisture retention properties are valued skin remedies used for smoothing and moisturizing, as an anti-inflammatory and for acne reduction.
- Arachidonic acid, an omega-6 fatty acid also found in peanut oil. This product moderates inflammation and plays an important role in the operation of the central nervous system.
- Eicospentaenoic acid, an omega-3 fatty acid and gives the same benefits as fish oil, which of course come from algae. Research suggests that EPA may improve brain activity, reduce depression and moderate suicidal behavior.
- Docasahexaenoic acid, an omega-3 fatty acid generally found in fish oil and is the most abundant fatty acid found in the brain and retina. DHA deficiency is associated with cognitive decline and increase neural cell death. DHA is depleted in the cerebral cortex of severely depressed patients.
- Gamma-linolenic acid, an omega-6 fatty acid found in vegetable oil and was first extracted from the evening primrose. It is sold as a dietary supplement for treating problems with inflammation and auto-immune diseases. Research is ongoing on its therapeutic value for cancer to suppress tumor growth and metastasis.
Algal components are commonly found in food ingredients. A normal family that uses normal dairy products may find 70% of the items in their food shopping cart contain algae ingredients. Carrageenans that make up the cell walls of several species of red and brown seaweeds are a family of linear polysaccharides. The carrageenan cell-wall material is a colloid, used as a stabilizer or emulsifier and is commonly present in dairy and bakery products.
Agar. This substance, a polysaccharide, solidifies almost anything that is liquid. Agar is a colloidal agent used for thickening, suspending, and stabilizing. However, it is best noted for its unique ability to form thermally reversible gels at low temperatures. Agar has been used in China since the 17th century and is currently produced in Japan, Korea, Australia, New Zealand, and Morocco.
Today, agar serves scientists globally as a gelatin-like medium for growing organisms in scientific and medical studies. Agar is used extensively in the pharmaceutical industry as a laxative or as an inert carrier for drug products where slow release of the drug is required. Bacteriology and mycology use agar as a stiffening agent in growth media.
Agar also is used as a stabilizer for emulsions and as a constituent of cosmetic skin preparations, ointments, and lotions. It is used in photographic film, shoe polish, dental impression molds, shaving soaps, hand lotions, and in the tanning industry. In food, agar is used as a substitute for gelatin, as an anti-drying agent in breads and pastries and also for gelling and thickening. Agar is used in the manufacture of processed cheese, mayonnaise, puddings, creams, jellies and in the manufacture of frozen dairy products.
Nori, the Japanese word for seaweed, is popular around the world but especially in Asia where it is served with a variety of names such as kombu, wakame, hai dai, laminaria and limu. Scottish cooks call it dulse and the Irish call their product dillisk. Amanori is specifically those foods made from the Porphyra species because it contains essential amino acids, vitamins and minerals. In Korea, Porphyra, is known as kim or lavor. It provides healthy foods that are free of the sugars and fats that are associated with the Western diet.
Wild populations of inland, freshwater algae have been collected and consumed since prehistoric times for their fresh taste and nutrient value. One of the most common, nostoc consists of long beaded chains and forms a gelatinous aggregation of filaments. The individual filaments are microscopic but aggregations occur as globules of all sizes and look similar to grapes.
The microscopic filaments of Spirulina do not form oval globules but often mass into floating clumps that are pushed against the shore by wind. Other algal species appear as threads of free floating masses or filaments clinging to rocks in fast moving water. Spirulina, in powdered form, leads most conventional foods in both total and usable protein. Only poultry and fish are superior with more than 45% usable protein. Spirulina matches meat and dairy products with 30% to 45% protein. Spirulina and nostoc offer more protein by weight than any other vegetable. Earthrise Nutritionals produces 500 tons of edible Spirulina each year at its 100 acre farm in Southern California.
Algal species selection will continue to be a critical issue for algal producers because the right species choice enhances cultivation, harvest, extraction and the value of products produced. Fortunately, the algal species collections offer extensive information on species in their collections and make those species reliably available at modest cost.
Adapted from: Green Algae Strategy: End Oil Imports and Engineer Sustainable Food and Fuel, 2008.
CHAPTER 7: Algal Cultivation
Algae grow in open, closed or semi-closed systems in round, long or tubular tanks that maximize access of the entire biomass to sunlight. Growth occurs only in the top layer, about two inches, of the growing medium unless mixing occurs. New cell growth blocks the sunlight for plants below. Semi-continuous mixing is necessary to give all the algae sufficient light. Some production systems put light sources near or in the water to augment sunlight.
Growth occurs based on a host of variables that not only constrain growth, but may change the algal composition. Primary variables include the following.
Light. Usually sunlight provides sufficient light but artificial light also works as well—especially for indoor growing systems. Some growing systems may be tilted to optimize orientation to the sun and reflected light. Several producers are experimenting with bent light using mirrors or glass cables and other are using LED lights that minimize energy consumption.
Mixing. Since most growth takes place in the top layer of the surface that faces the light source, mixing is imperative. Each cell needs to move in and out of the light for their light and dark growth periods as they take in CO2 and exhale O2. Algae are heavier than water and would sink away from their light source without mixing.
Algae grow so fast they become nutrient-limited quickly in still water. They cannot move and graze for food because they usually have no propulsion. Mixing brings nutrients and CO₂ to each algae cell and provides intermittent light exposure. Mixing also helps release O2 from the water to the atmosphere. Too much or too little mixing impedes growth and rough mixing methods may create cell damage from shear stress.
Some algae have evolved two interesting differentiated features: flagella and eye spots. At a specific growth stage, some algae grow flagella, slender projections from the body like sperm tails that move in a whip-like motion to propel the algae. The eye spot recognizes light and the flagella propel the plant toward the light. Movement is very slow, possibly an inch an hour.
Water. Algae grow well in nearly any kind of water. They are especially good at using photosynthesis to convert dissolved nutrients and metals in wastewater to green biomass where the metals can be removed and recovered. Production systems can use wastewater, grey water and saline or ocean water, depending on the species grown. Growing systems can recycle the water so the only loss comes from evaporation.
CO₂. Approximately half of the microalgal biomass dry weight is carbon, typically derived from CO₂ or carbonates, and is fed continually during daylight. Each 100 tons of algal biomass fixes roughly 183 tons of CO₂. Algae’s favorite food, CO₂, needs to be added as a gas or in bicarbonate form because cultivated algae grow too fast to be able to take sufficient CO₂ from the water. Most water is too dilute in CO₂ for high production. Compressed air blended with CO₂ up to 20%, typically provides carbon for algal photosynthesis. Industrial CO₂ or waste flue gasses are typical sources but some coal-fired power plants overproduce sulfur, which may inhibit algal growth. Some producers such as Solazyme use an organic carbon source in the form of acetic acid or glucose.
Nutrients. Algae feed their growth with the same fertilizers used for land plants but the fertilizers can come from waste streams that are too salty for land plants. Algal growth consumes far less nitrogen and other fertilizers per pound of biomass than food grains such as corn and the nutrients are easier and less expensive to apply. Dissolved chemical fertilizer or waste stream nutrients are utilized by algae with far more efficiency than land plants because the tiny single celled algae consume the nutrients directly and do not have to transport the nutrients long distances. Unused fertilizer also may be reused with the recycled water.
pH. The acidity of water may be specific to the type of algae produced. Controlling the water’s pH represents a good strategy for retarding growth of competing algae. Water pH is likely to be highest at noon due to the high photosynthetic activity, which consumes maximum CO₂.
Stability. Maintaining a stable growth environment presents difficulties with the high velocity of growth. The growing medium may retain too much of any nutrient or O2, which may create stress and or composition changes to the plants. Some producers capture released O2 and sell the pure gas as a value added product.
Algal biomass grows in ponds or containers called biofactories or cultivated algal production systems, (CAPS). Water, inorganic nutrients, CO₂ and light is provided to the algal culture to promote biomass growth. Algae prefer diffused light that is not too bright so some systems use shading that limits light and diffuses it. Various species produce best at specific temperatures so some systems use recycled water on the outside of the biofactory to maintain optimum temperature.
Even though CO₂ may be about 5% of production cost, that cost can be minimized by siting the biofactory near a power or manufacturing plant that produces CO₂. Nutrients may be provided from wastewater, recovered from the algal tank or harvested fertilizer. After the algal oil is removed, the remaining biomass contains considerable nutrients.
Closed systems offer the advantage that high nutrient water may be recycled through the system. This practice significantly lowers the cost of added nutrients. It also minimizes water loss to evaporation. Algaculture systems that use high-saline water, such as agricultural waste streams or brine water, produce a biomass with considerable salt that needs to be removed during co-product extraction. Some business models indicate using algae to harvest heavy metals from industrial wastewater, which are then extracted and sold on the chemicals market.
Harvest may occur daily by filtering, centrifuge or flocculation. The cells suspended in the broth are separated from the water and residual nutrients are recycled to biomass production. Algal oil is extracted from the recovered biomass and converted to biodiesel. Some of the non-oil biomass may be used as animal feed, fertilizer and for other co-products.
Part of the spent biomass undergoes anaerobic digestion to produce biogas that generates electricity, which powers the biomass mixing and water transport. Effluents from anaerobic digestion may be used for more algal production or as nutrient-rich irrigation water. Most of the power generated from the biogas is consumed in biomass-production and any excess energy may be sold to the grid. Some systems use solar panels with photovoltaic cells to convert solar energy directly to electricity, which is typically used directly or stored in batteries.
In a continuous culture, fresh culture medium is fed at a constant rate and the same quantity of microalgal broth is withdrawn. Feeding stops during the night but mixing continues to prevent biomass settling. As much as 20% of the biomass, produced during daylight, may be consumed during the night to sustain the cells until sunrise. Nightly biomass loss depends on the growth light level, growth temperature and the temperature at night. Some production systems are experimenting with nightlights to boost productivity.
Microalgae contain high, but variable, percentages of the key macronutrients: typically 20-50% protein, 5-30% carbohydrates and 10-30% lipids, with about 10% ash or waste. The proportions of each nutrient may be modified by species selection, varying growth conditions or by harvesting the algae at different growth stages. Most species are rich in amino acids and offer a variety of pigments. The sugar composition of polysaccharides is highly variable, but most species have high proportions of glucose, 20-87%. Microalgae contain significant quantities of micronutrients and antioxidants such as vitamins, ascorbic acid, riboflavin, carotenoids and a variety of novel lipids.
After the oil component is used for biofuel, the remaining high protein biomass may be de-moistured and stored in a convenient form such as a cake, which does not require refrigeration and has about a two year shelf life. The algal cake may be separated into various food, food ingredients, fodder, fertilizer, fine medicines or other components.
Algal production for food, fuel, medicines or other co-products can be carbon neutral because the power needed for producing and processing the algae can come from the methane produced by anaerobic digestion of the biomass residue remaining after oil extraction. The modest energy requirement for mixing and harvest may also come from other non-carbon sources such as wind, geothermal or solar.
The harvested biomass is extremely malleable in the sense that it can be stored in the same form as corn, wheat, rice or soy products. These include protein-rich milk, soft mash of any size, shape or texture, tortilla, cracker or flour. The biomass may be made into texturized vegetable protein with added fiber or extruded to make additives for meats that improve moisture retention and increase protein while lowering fats.
Our future foods are likely to be enriched with algae and advanced compounds from algae.
Adapted from: Green Algae Strategy: End Oil Imports and Engineer Sustainable Food and Fuel, 2008.
CHAPTER 8: Did Algae Make Us Human?
Algae saved our planet 3.5 billion years ago by transforming the hot and deadly CO2 and methane atmosphere to enough oxygen to support life. Only 2 million years ago, algae may have performed another incredible feat by providing the micronutrients that triggered human brain enlargement. Brains that expanded three times larger than chimpanzees, differentiated our Homo ancestors from their pre-human and primate cousins.
A mystery nutrient source triggered brain enlargement, encephalation, around 2 million years ago. Scientists agree that early hominoids had to find a more energetic diet richer than their prior primate diet of nuts, leaves, bark, shoots, roots and insects. The new diet needed to be rich in vital nutrients, especially protein and omega-3s to support brain enlargement. Textbooks suggest that early Homo took a one step path to encephalation by expanding their diet to include savanna game meat, which would have provided the energy and nutrients necessary to develop and support larger brains.
However, meat acquisition would have required small brained (slightly larger than chimp brains) and scrawny early hominoids to compete with wild animals to acquire meat. Early Homo sacrificed muscle mass, size and speed for walking upright and a slight increase in brain size. The game meat scenario ignores the substantial energy and survival risk associated with competing with much bigger, faster and stronger wild animals with specialized scavenger and hunting skills. African predators 2 million years ago were twice the size they are today.
The human brain enlarged a million years before hunting weapons or cooking fires were invented. Had early Homo hunted meat without weapons, they would have most likely become the food chain. Even had they found meat, they lacked the teeth to tear off or masticate raw meat. Their stomachs could not digest raw meat, which probably would have given them raging diarrhea. A nutritious, safe, convenient and digestible food source rich in omega-3s must have preceded game meat consumption to permit the initial stages of brain enlargement.
Omega-3 fatty acids
DHA comprises 27% of the polyunsaturated fat, and 97% of the omega-3 fatty acids in the brain. Arachidonic acid (ARA), an omega-6 long-chain polyunsaturated fat, comprises 35% of the polyunsaturated fat, and 48% of the omega-6 fatty acids in the brain. Together DHA and ARA account for nearly two-thirds of the structural fat in the brain. They are essential for normal brain development and function as well for operations of the eyes and heart. These fatty acids are concentrated in the region of the brain responsible for complex thinking skills — critical for food acquisition.
Mammals have a limited capacity to synthesize DHA and ARA from dietary precursors, so fatty acids were likely the limiting nutrients that constrained the evolution of larger brain size in most mammalian lineages. Wild plant foods available on the African savanna, grasses, grains, tubers and nuts contain negligible ARA and DHA. Muscle tissue and organs of wild African ruminants would have provided only moderate levels of these key fatty acids.
Down the food chain
Rather than moving up the food chain to game meat, early hominoids’ first step may instead have been down the food chain when they ingested algae in their drinking water. Consuming algae may have been intentional but more likely was incidental because the tiny algal cells were visible only in the sense that they turned the water slightly green. The lakes and wetlands in the Rift Valley where humans developed larger brains are home to some of the oldest lakes and wetlands on Earth that produce plentiful natural stands of the high protein and nutrient rich spirulina algae. Spirulina is the best selling algal nutritive supplement on the market today because it provides a complete set of essential nutrients. A hominoid tribe on the lee side of an algae lake may have ingested several grams of algae daily in their drinking water. These few grams of algae would not have provided sufficient roughage or protein for a full diet. Algae would have acted as a natural food supplement to supply the essential nutrients, vitamins and antioxidants that provided the green spark for encephalation.
Early Homo may have been attracted to the green sweet water because their bland, dry and gritty diet was nearly devoid of sweetness. Algae attract a wide variety of other nutritious microorganisms including yeasts, fungi, bacteria, viruses and other microorganisms that would have provided additional nutrient value. When ingested, algae create a feeling of satiation from moderated glucose release, which would have been a godsend for mothers with hungry infants. Algae also facilitate digestion so mothers may have made sure their offspring drank green sweet water loaded with algae after meals. On the lee side of lakes and wetlands, the wind blows algae into mats that could have been harvested easily with a sweep of the hand. These concentrated algae may have been attractive for its sweet taste as well as protein value.
As their brains enlarged, early Homo may have expanded their diet by exploiting the aquatic ecosystem for algal feeders loaded with algal protein and nutrients such as invertebrates, shell and fin fish, insects and amphibians. Algal nutrients were available locally, year round and were easy to harvest and ready to eat or to dry and store for later consumption. Algae may have served as the original tasty convenience food and provided healthy protein with a full set of critical amino acids, essential fatty acids that supported brain and body development as well as critical vitamins and minerals. Indigenous populations in Africa continue to harvest algae from mats floating on the water to use as nutritional supplements.
Early human brains were not the only body part that benefited from algae. Today the four most prevalent deficiency diseases globally in public health are: malnutrition, nutritional anemia (iron and B12 deficiency), xerophthalmia (vitamin A deficiency) and endemic goiter (iodine deficiency). Each of these nutrient deficiencies would have challenged pre-humans that had neither hunting weapons nor hunting skills and also lacked cooking fires. Forest and savanna plant foods, especially in winter and spring, would have imposed severe nutrient deficiencies on early hominoids. Without cooking fires to soften cell walls and release nutrients in foods such as nuts, grains, shoots and roots, much of the nutrient value would have been lost to early Homo.
It may seem improbable that a tiny algal supplement can provide sufficient vitamin A, iodine, iron, zinc and other nutrients even when the local diet does not. Typically, these critical trace elements exist in the local water but in extremely weak dilution. People, especially children, are unable to drink enough water to acquire sufficient iodine. In many ecosystems, little fresh water is available for drinking. Algae’s secret to high nutrient value stems from its ability to bioaccumulate nutrients in water at 1,000 times ambient levels. This means that even when some nutrients, minerals or vitamins may be lacking in human diets, algae can concentrate those nutrients in the green biomass.
Once hominoid brains and bodies reached critical mass, Homo sapiens expanded their diets and eventually became hunters. The first fossil record of a hunting weapon is only 400,000 years old. The addition of hunting weapons and cooking fires then enabled a more diverse diet and the development of modern human brains, communication and cooperation.
The dietary path to becoming human may not have been one step up the food chain to harvest savanna game meat. More likely, our ancestors first waltzed two steps down the aquatic food chain for the nutritional benefits of algae, especially the omega-3s. After their brains had enlarged thanks to algae nutrients, our ancestors were prepared to take the big step up the terrestrial trophic food web to harvest game meat.
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