Biodiesel from Algae - Information, Resources and Links for Algal, Alga Bio-diesel

Biodiesel from Algae – Info, Resources & Links

While a number of bio-feedstock are currently being experimented for biodiesel production, algae have emerged as one of the most promising sources for biodiesel production. Though research into algae as a source for biodiesel is not new, the current oil crises and fast depleting fossil oil reserves have made it more imperative for organizations and countries to invest more time and efforts into research on suitable renewable feedstock such as algae.

Just by way of history, petroleum is widely believed to have had its origins in kerogen, which is easily converted to an oily substance under conditions of high pressure and temperature. Kerogen is formed from algae, biodegraded organic compounds, plankton, bacteria, plant material, etc., by biochemical and/or chemical reactions such as diagenesis and catagenesis. Several studies have been conducted to simulate petroleum formation by pyrolysis. On the basis of these findings, it can be inferred that algae grown in CO2-enriched air can be converted to oily substances. Such an approach can contribute to solving two major problems: air pollution resulting from CO2 evolution, and future crises due to a shortage of energy sources.

While algae are one of the more promising feedstocks owing to their widespread availability and higher oil yields, it is felt that there are not enough web resources that provide comprehensive information on biodiesel production from algae. This web page intends to be a one-stop resource for information and web links for biodiesel production from algae.

We hope that you find this page to be of use.

Any feedback and suggestions may kindly be sent to Narsi @ [email protected]

Note:

The content for this page have been derived from Oilgae – a web resource dedicated to providing comprehensive resources for oil and fuel production from algae. See Oilgae – Biodiesel from Algae for more and up-to-date info on this topic.

See also:

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Get the latest news on oil and biodiesel from algae at the Oilgae Blog

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See also: Some interesting energy-related questions from Billion Dollar Questions

· Are biofuels sustainable in the long term?

· How long will oil last?

· What are the alternative energy options available?

The following are the sections in this page

What are algae?

Where do algae grow?

What are algae comprised of?

How are algae cultivated for biodiesel?

What are the existing sources of algae for biodiesel production?

What are the oil yields from algae?

What is the process by which the oil is extracted from algae?

How is biodiesel from algae different from biodiesel from other plant/vegetable oils?

Talking practically, is it feasible to produce biodiesel from algae on a large scale?

What can be done with the algae left-over after the extraction of oil ( the “dried algae”)?

More Points & Links on Biodiesel from Algae

Research on Algae & Biodiesel from Algae

Latest News & Updates on Biodiesel from Algae

Appendix

1. What are algae?

Algae (singular alga) is a term that encompasses many different groups of living organisms. Algae capture light energy through photosynthesis and convert inorganic substances into simple sugars using the captured energy. Algae range from single-celled organisms to multi-cellular organisms, some with fairly complex differentiated form

Algae have been traditionally regarded as simple plants, and some are closely related to the higher plants.

Forms of Algae

The main branches/lines of algae are:

Chromista - this line includes the brown algae, golden brown algae, and diatoms. The plastids in these algae contain Chlorophylls A and C. ( see: Brief Introduction to the Phaeophyta, Brown Algae – from Wikipedia)
The Red Line – this is an early branch of marine algae containing just Chlorophyll A. Red algae can often be seen coating wave washed rocks. A characteristic of red algae is that their plastids contain only one type of chlorophyll -- chlorophyll a. This is different from green algae and plants which have both chlorophyll a and b. (see: Introduction to the Rhodophyta, Red Alga – from Wikipedia)
Dinoflagellates – these evolved on a separate line that includes, surprisingly, the ciliated protists. (see: Introduction to the Dinoflagellata from UMCP, Berkeley, Dinoflagellate Information – from MBARI, Dinoflagellate – from Wikipedia)
The Euglenids – this independent line of single celled organisms that include both photosynthetic and non-photosynthetic species (see: Euglenid – from Wikipedia)
The Green Line, is related to plants. Plants and green algae have chlophylls A and B. ( see also: Introduction to Green Algae)

The three most prominent lines of algae are the brown algae (Chromista), the red algae, and the green algae, of which some of the most complex forms are founds among the green algae. This lineage eventually led to the higher land plants. The point where these non-algal plants begin and algae stop is usually taken to be the presence of reproductive organs with protective cell layers, a characteristic not found in the other alga groups.

See also:

2. Where do algae grow?

Algae are some of the most robust organisms on earth, able to grow in a wide range of conditions.

Algae are usually found in damp places or bodies of water and thus are common in terrestrial as well as aquatic environments. However, terrestrial algae are usually rather inconspicuous and far more common in moist, tropical regions than dry ones, because algae lack vascular tissues and other adaptions to live on land

As mentioned above, algae grow in almost every habitat in every part of the world. The following are examples of non-marine (loosely termed 'freshwater' here) habitats.

Animals: Reported substrates include turtles, snails, rotifers, worms, crustacea and many other animals

Aquatic plants: Algae grow on and inside water plants (including other algae)

Artificial substrates: Wooden posts and fences, cans and bottles etc. all provide algal habitats.

Billabongs & lagoons: Rich microalgal habitats, particularly for desmids.

Bogs, marshes & swamps

Farm Dams

Hot springs

Lakes

Mud and sand

Ponds (ephemeral), puddles, roadside ditches and rock pools

Reservoirs

Rivers

Rock (internal & surface)

Saline Lagoons

Saline Lakes & Marshes

Salt marshes and salt lakes

Snow

Soil

Streams

Terrestrial plants

3. What are algae comprised of?

Algae are made up of eukaryotic cells. These are cells with nuclei and organelles. All algae all have plastids, the bodies with chlorophyll that carry out photosynthesis. But the various lines of algae can have different combinations of chlorophyll molecules; some have just Chlorophyll A, some A and B, and other lines, A and C.

All algae primary comprise of the following, in varying proportions: Proteins, Carbohydrates, Fats and Nucleic Acids. While the percentages vary with the type of algae, there are algae types that are comprised up to 40% of their overall mass by fatty acids. It is this fatty acid (oil) that can be extracted and converted into biodiesel.

Table 1 - Chemical Composition of Algae Expressed on A Dry Matter Basis (%)

Strain	Protein	Carbohydrates	Lipids	Nucleic acid
Scenedesmus obliquus	50-56	10-17	12-14	3-6
Scenedesmus quadricauda	47	-	1.9	-
Scenedesmus dimorphus	8-18	21-52	16-40	-
Chlamydomonas rheinhardii	48	17	21	-
Chlorella vulgaris	51-58	12-17	14-22	4-5
Chlorella pyrenoidosa	57	26	2	-
Spirogyra sp.	6-20	33-64	11-21	-
Dunaliella bioculata	49	4	8	-
Dunaliella salina	57	32	6	-
Euglena gracilis	39-61	14-18	14-20	-
Prymnesium parvum	28-45	25-33	22-38	1-2
Tetraselmis maculata	52	15	3	-
Porphyridium cruentum	28-39	40-57	9-14	-
Spirulina platensis	46-63	8-14	4--9	2-5
Spirulina maxima	60-71	13-16	6-7	3-4.5
Synechoccus sp.	63	15	11	5
Anabaena cylindrica	43-56	25-30	4-7	-

Source: Becker, (1994)

SERI Microalgae Culture Collection - Wikipedia

Preliminary Report of Distribution of Aliphatic Hydrocarbons in Algae & Bacteria (PDF)

Chemical Constituents of Marine Algae off Karachi Coast (PDF

4. How are algae cultivated for biodiesel?

Like plants, algae require primarily two components to grow: sunlight and carbon-di-oxide. Like plants again, they use the sunlight for the process of photosynthesis. Photosynthesis is an important biochemical process in which plants, algae, and some bacteria convert the energy of sunlight to chemical energy. This chemical energy is used to drive chemical reactions such as the formation of sugars or the fixation of nitrogen into amino acids, the building blocks for protein synthesis. (see Photosynthesis – from Wikipedia)

Since algae need for their growth sunlight, carbon-di-oxide and water, they can cultivated in open ponds. However, the unassisted growth in open ponds is slow, owing to the lower concentration of carbon-di-oxide; where carbon-di-oxide concentrations are increased artificially, higher growth rates can be achieved in open ponds as well. Alternatively, algae could be grown in closed structures called photobioreactors, where the environment is better controlled than in open ponds. While the costs of setting up and operating a photobioreactor would be higher than for those for open ponds, the efficiency and higher oil yields from these photobioreactors could be significantly higher as well, thus offsetting the initial cost disadvantage in the medium and long run.

Finding algae strains to grow isn't too difficult. Cultivating specific strains of algae for biodiesel could be however a bit more difficult, as they can require high maintenance and could get easily contaminated by undesirable species.

Photobioreactors

A photobioreactor is an equipment that is used to harvest algae. Photobioreactors can be set up to be continually harvested (the majority of the larger cultivation systems), or by harvesting a batch at a time (like polyethlyene bag cultivation). A batch photobioreactor is set up with nutrients and algal seed, and allowed to grow until the batch is harvested. A continuous photobioreactor is harvested either continually, as daily, or more frequently.

Some types of photobioreactors include:

· glass or plastic tubes

· tanks

· plastic sleeves or bags

Growing algae at home

Take a container and add a small amount of algae culture. If your plans for growing algae are towards producing biodiesel feedstock, you will need to find specific algae strains. Adding an aquarium bubble stone increases growth and circulates the algae. The only requirements for this type of system are CO2, (ambient CO2 is sufficient, though you're growth rate will be slower), nutrients, such as fertilizer or manure, and a light source. The optimal temperature range will depend on the strain you are using.

Lighting

Some sources that can be used to provide the light energy required to sustain photosynthesis include

· Fluorescent bulbs

· LEDs, or

· Natural sunlight

Some more thoughts on algae growth and cultivation

· It could also be worth thinking about how (or if) marine algae could be grown – perhaps through iron fertilization - in otherwise unproductive (high-nitrogen-low-chlorophyll) regions of the open oceans.

Research on Algae Cultivation

· The NREL (national Renewable Energy Laboratory, part of the Department of Energy) conducted research into algae production. NREL favoured unlined “raceway” ponds which were stirred using a paddle wheel, and had carbon dioxide bubbled through it. The water used for these ponds is wastewater (treated sewerage) freshwater, brackish water, or salt water, depending on the strain of algae grown. The algae should be a native to the region.

· Other countries, notably Japan, are interested in closed systems; however these systems (at least from NREL perspective) are very expensive.

6. Existing Sources of Algae for Biodiesel

The existing large-scale sources are of algae are:

Terrestrial & Aquatic plants: Algae grow on and inside water plants (including other algae)

Billabongs & lagoons: Rich microalgal habitats, particularly for desmids.

Bogs, marshes & swamps - Salt marshes and salt lakes

Sewages & Garbage

Biodiesel from Sewage, Article & Discussions - SlashDot

The Power of LeftOvers – Biodiesel from Garbage

Farm Dams & Large Water Reservoirs

Hot springs

Rivers, Lakes & Ponds, Puddles etc. – also Saline Lagoons, Saline Lakes & Marshes

Soil, Mud, Sand & Rocks (internal & surface)

Snow

5. Oil Yield from Algae

Microalgae contain lipids and fatty acids as membrane components, storage products, metabolites and sources of energy. Algal strains, diatoms, and cyanobacteria (catagorised collectively as "Microalgae") have been found to contain proportionally high levels of lipids (over 30%). These microalgal strains with high oil, or lipid content are of great interest in the search for a sustainable feedstock for the production of biodiesel. As could be seen from Table 1, algae contain anywhere between 2% and 40% of lipids/oils by weight.

Lipid accumulation in algae typically occurs during periods of environmental stress, including growth under nutrient-deficient conditions. Biochemical studies have suggested that acetyl-CoA carboxylase (ACCase), a biotin-containing enzyme that catalyzes an early step in fatty acid biosynthesis, may be involved in the control of this lipid accumulation process. Therefore, it may be possible to enhance lipid production rates by increasing the activity of this enzyme via genetic engineering.

The following species listed are currently being studied for their suitability as a mass-oil producing crop, across various locations worldwide.

· Neochloris oleoabundans - Neochloris oleoabundans is a microalga belonging in the class Chlorophyceae

· Scenedesmus dimorphus - Scenedesmus dimorphus is a unicellular algae in the class Chlorophyceae

· Euglena gracilis

· Phaeodactylum tricornutum - Phaeodactylum tricornutum is a diatom

· Pleurochrysis carterae - Pleurochrysis carterae is a unicellular coccolithophorid alga that has the ability to calcify subcellularly. It is a member of the class Haptophyta (Prymnesiophyceae)

· Prymnesium parvum - Prymnesium parvum is a toxic algae

· Tetraselmis chui - Tetraselmis chui is a marine unicellular alga

· Tetraselmis suecica

· Isochrysis galbana - Isochrysis galbana is a microalga.

Nannochloropsis salina – This is also called Nannochloris oculata. In the same group are Nannochloris atomus Butcher, Nannochloris maculata Butcher, Nannochloropsis gaditana Lubian, and Nannochloropsis oculata (Droop)
Algal strains such as Botryococcus braunii can produce long chain hydrocarbons representing 86% of its dry weight
Nannochloris sp.
The strains of Algae most favoured by the NREL researchers were Chlorophyceae (green algae). Green algae tend to produce starch, rather than lipids. Green algae have very high growth rates at 30oC and high light in a water solution of type I at 55 mmho/cm.
The other favoured algae (by NREL researchers) is Bacilliarophy (diatom algae). However, the diatom algae needs silicon in the water to grow, whereas green algae requires nitrogen to grow. Under nutrient deficiency the algae produced more oils per weight of algae, however the algae growths also were significantly less. While certain green algae strains are very tolerant to temperature fluctuations, diatoms have a fairly narrow temperature range.

Oil Yield from Algae Research

· Research into cloning the gene that encodes ACCase from the eukaryotic alga Cyclotella cryptica has been undertaken, by isolating this gene. Research found that the amino acid sequence of ACCase deduced from this gene exhibited a high degree of similarity to the sequences of animal and yeast ACCases in the biotin carboxylase and carboxyltransferase domains, but less similarity exists in the biotin carboxyl carrier protein domain. Comparison of the genomic nucleotide sequence to the sequences of cDNA clones has revealed the presence of two introns in the gene. Research teams are currently constructing expression vectors containing this gene and developing algal transformation protocols to enable overexpression of ACCase in C. cryptica and other algal species.

6. What is the process by which the oil is extracted from algae?

While more efficient processes are emerging, a simple process is to use a press to extract a large percentage (70-75%) of the oils out of algae. The remaining pulp can be mixed with cyclo-hexane to extract the remaining oil content.

The parameters to be considered while evaluating the ideal algae processor are:

Capacity/throughput of the system
Speed/density

Centrifuges

A centrifuge is a useful device for both biolipid extraction from algae and chemical separation in biodiesel.

Centrifuge Applications

There are several steps in the biodiesel production process where centrifugation is useful.

Feedstock preparation - In this case, algae must first be separated from its medium, then the oil extracted from the algae.
Separation of transesterification products – Biodiesel and glycerine must be separated, and any leftover reactants removed.
Water wash – Biodiesel can be washed of soap and glycerine using a centrifuge.
Magnasol solids removal - As an alternative to water washing, it may be possible to wash the biodiesel in Magnasol.

7. How is biodiesel from algae different from biodiesel from other plant/vegetable oils?

The biodiesel from algae in itself is not any different from biodiesel produced from vegetable/plant oils. All biodiesel essentially are produced using triglycerides (commonly called fats) from the plant/algal oils.

The difference is however in the yield of oil, and hence biodiesel. According to some estimates, the yield (per acre, say) of oil from algae is over 200 times the yield from the best-performing plant/vegetable oils.

Summary of advantages of biodiesel produced from algae

Higher yield and hence – hopefully – lower cost
Algae can grow practically in every place where there is enough sunshine
The biodiesel production from algae also has the beneficial by-product of reducing carbon and NOx emissions from power plants, if the algae are grown using exhausts from the power plants.

8. Talking practically, is it feasible to produce biodiesel from algae on a large scale?

Theoretically, biodiesel produced from algae appears to be the only feasible solution today for replacing petro-diesel completely. No other feedstock has the oil yield high enough for it to be in a position to produce such large volumes of oil. To elaborate, it has been calculated that in order for a crop such as soybean or palm to yield enough oil capable of replacing petro-diesel completely, a very large percentage of the current land available needs to be utilized only for biodiesel crop production, which is quite infeasible. For some small countries, in fact it implies that all land available in the country be dedicated to biodiesel crop production. However, if the feedstock were to be algae, owing to its very high yield of oil per acre of cultivation, it has been found that about 10 million acres of land would need to be used for biodiesel cultivation in the US in order to produce biodiesel to replace all the petrodiesel used currently in that country. This is just 1% of the total land used today for farming and grazing together in the US (about 1 billion acres). Clearly, algae are a superior alternative as a feedstock for large-scale biodiesel production.

In practice however, biodiesel has not yet been produced on a wide scale from algae, though large scale algae cultivation and biodiesel production appear likely in the near future (4-5 years).

9. What can be done with the algae left-over after the extraction of oil ( the “dried algae”)?

The flakes left over from biodiesel squeezing can be processed into ethanol. It can also be used as livestock feed, such as chicken feed.

Algal biomass has other potential on- and off-farm uses. Although it has primarily been considered as an alternative high-grade protein source in animal feed, algal biomass with a balanced N:P ratio is a potentially valuable organic fertilizer. It may also have some biocontrol properties. Algal biomass is also reported to be particularly suitable for pisciculture.

10. More Points & Links on Biodiesel from Algae

Some algae can grow in saline water. It is worth exploring the possible economic production of biodiesel from algae using saline ground water in the growing ponds, which are covered by greenhouses as used by the horticultural and floral industries. Once the water becomes too salty for the algae to grow, it could be drained to evaporation ponds to recover the salts for use by the chemical industry.
At an assumed recovery rate of 30% of the weight of algae, 45.6 tonnes of oil/hectare/year can be produced from Diatom algae.
Algae production can be increased by increasing the carbon dioxide concentration in the water.
For best conditions, algae ponds would need to be covered by greenhouses, which would require additional capital expediture to set up.
Different algae species produce different amounts of oil. Some algae ( diatoms for instance) produce up to 50% oil by weight.
Cyanobacteria, also known as blue-green algae, use solar energy to split water into oxygen and hydrogen, but they do it under limited conditions and for very brief periods of time. One of the goals is to extend the time and conditions under which these bacteria produce hydrogen. The major challenge that must be overcome is that cyanobacteria only produce hydrogen in the absence of oxygen. Success is dependent upon finding oxygen-tolerant strains of cyanobacteria.

See also:

11. Research on Algae & Biodiesel from Algae

· Some recent studies have been directed at investigating the feasibility of using anaerobic digestion as a technique to recover solar energy embodied in the excessive algal biomass production as a replacement fuel. The three major issues restricting the economic and technical feasibility of anaerobic fermentation of algal sludge are: 1) The low energy density of the dewatered sludge as obtained from algal removal techniques, 2) Green algal sludge is relatively resistant to anaerobic biodegradation 3) The high nitrogen content of algal biomass leading to ammonia toxicity in the anaerobic digester environment.

12. Appendix

Appendix A - Biodiesel from Algae Fed on Coal-fired Power Station Exhausts

The idea is that carbon dioxide from coal fired power station is used to produce algae, which is used to make biodiesel and natural gas.
If the carbon dioxide from a coal fired power station is pumped directly through a pipeline to a near by algae ‘farm’, then the amount of carbon dioxide absorbed into the algae is around 30%. The reason the value is so low is that the algae does not grow at night hence all carbon dioxide pumped then, goes straight into the atmosphere. In addition, the algae grow faster in summer than in winter. The other method is to concentrate the carbon dioxide and pressurize it and truck it to the algae farm, and then release the carbon dioxide into the ponds as and when it is needed. It is hoped that >95% of the carbon dioxide can be consumed by this method. A paddle wheel would move the water at a steady flow. The ponds would be unlined, that is made of compact clay, with gravel in the bottom to ensure no soil becomes agitated into the water.

Some estimates of biodiesel production from algae using CO2 from coal-fired power stations

Algae yield 100 tonnes/ha.
2.2 tonnes carbon dioxide needed / 1 tonnes algae
Water needed 4m3/m2. Most of the water is lost due to evaporation, some is consumed by the algae, and some is lost in the harvesting of the algae.
A 500 MW coal fired power station produces 3.67x106 tonnes of carbon dioxide
3.5 barrels of biodiesel per tonne algae produced
6 MJ methane per tonne algae generated
Energy density of LNG is 15.2 kWh/kg and density is 448 kg/m3

Appendix B – Diatoms

One of the more well-researched species of algae are the diatoms.

Biotechnological applications of diatoms are still in development. Because of the photoautotrophic status of the majority of diatoms, microalgal cultures suffer from the limitation of light diffusion, which requires the development of suitable photobioreactors. Thus, genetically engineered microalgae that may be cultivated in heterotrophic conditions present a new opportunity. Most of the time, metabolic stress conditions lead to an overproduction of the products of interest, with a decrease in biomass production as a consequence. Outdoor cultures in open ponds are usually devoted to aquaculture for the feeding of shrimps and bivalve molluscs (commercial production), while closed axenic indoor/outdoor photobioreactors are used for biotechnological compounds of homogeneous composition (still at the laboratory scale). In addition to the optimum culture conditions that have to be taken into account for photobioreactor design, the localisation of produced metabolites (intra- or extracellular) may also be taken into account when choosing the design. Microalgal cell immobilisation may be a suitable technique for application to benthic diatoms, which are usually sensitive to bioturbation and/or metabolites which may be overexpressed.

Currently diatoms (an algae) are being investigated for biodiesel and other things, including medicine. It appears more basic research about them is needed to be able to manage large scale diatom farms economically. Diatom study includes species that like to attach themselves to coral, sea weed , or strip of plastic. Thus harvesting diatoms is more complicated than pumping them from the sea, or a pond.

Biodiesel from Algae – Info, Resources & Links

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