With the myriad of existing species of algae, it should come as no surprise that algae biofuel is also known under a plethora of names. Algal/algae biofuel and algae biodiesel are just a couple of them. And while the main facts about algae are common knowledge (e.g.: algae are damaging to underwater organisms), algal biodiesel still remains something of a wager.
It’s a rather risky wager, at that.
The fact remains that the 2008 gasoline price boom, which saw prices skyrocket to $7/gallon, has green-lighted a tighter race than ever before for new sustainable fuels. Can algae provide the environmentally sound alternative to expensive oil imports and the increasingly lower reserves global fuel resources?
Alga (with ‘algae’ being the plural form) grows naturally and plentifully all over the world. The species is resilient and can grow even in difficult environmental conditions, so producing virtually limitless amounts of it sounds almost feasible.
Image source: Durham Township
Algae as a biofuel: Definition
This liquid fossil fuel alternative called biofuel from algae extracts energy-producing oils from algae. While algae fuel does produce CO2, the main difference from fossil fuels is that the output of emissions is limited to the CO2 that algae photosynthesis released in the air, while the plant was growing.
The algae biofuel process
To learn more about how algae biodiesel is produced, let’s run through all stages of the process—from how algae emerge and thrive, to the actual technologies turning them into fuel.
- About the algae plant family
It comprises over 100,000 species, classed as plant-like organisms. They literally come in all shapes, sizes, and hues, from green to red and brown. Very small protozoa can be found on the surface of ponds while the ocean floor is home to massive seaweed bushes.
Image source: Cellnique
Kelp, moss, and fungus are also algae. Since, in terms of oil content, not all algae was created equal, it’s worth knowing that pond scum is the best species to make biodiesel from.
- Growing and harvesting algae for fuel
To grow algae, you don’t need more than carbon dioxide, water, and natural sunlight. They can be easily grown indoors, by just about anyone. That is, of course, truer in theory than in reality, since this is a complex, time-consuming process, which can also be dangerous to the average user.
Meanwhile, the challenge to using algae for fuel is figuring out how to grow enough to cover global needs. At an industrial scale, there are two main methods to grow algae: in open-pond and closed-pond systems. A third system which is also often used is vertical growth.
Open-pond algae growing
This is the most natural and unobtrusive algae growing method, in which they are planted in naturally auspicious areas around the globe, on open ponds. Favorable climates have to be hot and sunny to obtain the maximum yield of algae. However, this method does come with some disadvantages:
- Bad weather can affect algae crops;
- Bacteria and other parasites can contaminate the algae;
- The water needs to be kept at a certain stable temperature, which is often difficult to achieve.
A closed-tank bioreactor contains massive, circular drums, in which algae are grown indoors. This helps eliminate all the risks of tampering with the efficiency of growing algae outdoors. Closed-pond systems operate with genetically manipulated algae, which are primed to grow to maximal levels, to then be harvested on a daily basis. This, of course, helps maximize the yield.
A currently researched alternative to such systems is fermentation, wherein the algae is fed sugar to help it grow faster. The advantage of this option is that it enables algae growth anywhere in the world. However, scientists are still looking into sustainable sources of sugar.
This system, also known as closed-loop production, has been specifically developed by biodiesel producing companies as a more efficient alternative to open-pond systems. In this system, the algae are placed in bags made of transparent plastic, which means they get maximum exposure to sunlight on both sides.
The stacks of plastic bags go all the way up and are covered as a protective measure against rain and infestations with bacteria or other micro-organisms.
Image source: Rady School
- Extracting oils from algae
Very simply put, harvesting the lipids from the walls of algae cells is a lot like extracting the juice from oranges. The key difference is an extra chemical reaction, which comes into play.
There are several ways of extracting these lipids from algae; the following 3 are those most frequently used:
- Oil press. At once the simplest and most popular algae oil extraction method, it works a lot like the olive press. Its efficiency rate is up to 75% of oil extracted from the algae.
- Hexane solvent. In the first stage of this process, algae is pressed to squeeze out the lipids. The leftovers are mixed with the solvent, which cleans them, filters out the impurities, and ensures chemical-free oils.
- Supercritical fluids. The most efficient method, with an extraction rate of up to 100 percent, is also the most technologically complex and work-intensive. The supercritical fluid in question is carbon dioxide, which is blended with pressurized, heated algae and thus turns all of it into oil.
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There are several methods that can be used to extract oil from algae and manufacturing companies are researching as many diverse ones as possible, in order to obtain the maximum yield of algal biodiesel.
- Refining algae oils
This organic chemistry process is known under the tongue-twisting name of transesterification. This process makes use of sodium hydroxide as a catalyst (ester) and combines it with an alcohol (usually, methanol). A chemical reaction then occurs, resulting in a different alcohol and ester.
In the case of algal biofuel, the result is a glycerol-biodiesel, which needs to be subsequently refined to do away with the glycerol.
A brief history of exploiting algae for fuel
It all started in 1978, in a fuel pricing climate similar to the one we saw more recently, after the oil price boom. Under President Jimmy Carter’s mandate, a fuel crisis occurred and prices went through the roof.
To assuage the crisis, the government initiated The Aquatic Species Program, through the National Renewable Energy Laboratory. The researchers tested over 3,000 algae species and determined that the large amounts of this plant can be used to heat homes and fuel vehicles.
Sadly, in the mid-’90s, R&D on algae biofuel was interrupted, as research programs got defunded due to a relatively significant decrease in oil prices. It was only in the early years of the new millennium that biofuels came back into focus—which makes the technology to harvest biofuels still relatively new and under-researched.
Image source: Inhabitat
Algae biofuel – Pros and cons
- Algae fuel is more efficient than other types of biofuel. Producers claim they are able to produce over 100,000 gallons/year, based on what algae species they’re using, how it was grown, and how the oil is extracted. 100 acres of algae could potentially yield 10 million gallons of biodiesel. To completely replace conventional fuel, 140 billion gallons of algae biofuel would be required each year. This translates into 95 million acres of land—which is far less than what would be required for corn, palm, soy, hemp, or other biofuels.
- Producing biodiesel is environmentally friendly. During the process of making fuel from algae, the plants go through photosynthesis, which basically means they extract the CO2 in the air and produce oxygen to take its place. This is why biodiesel plants are being built next to massive CO2 producers, such as conventional power plants. Moreover, algae has no impact on freshwater resources, since it can be grown using saline and wastewater. This actually helps prevent the infestation of water sources with fertilizers.
- Algae fuels have no negative impact on food crops. Since algae are grown on water, they don’t take up much-needed farm land for food crops. To boot, pressed algae can be turned into fertilizer and feedstock, without any additional consumption of other raw materials.
- Open-pond systems are difficult to maintain. This is mostly because the water needs to be kept at a constant specific temperature and also enriched with carbon dioxide. For the time being, rendering closed-pond systems as efficient as possible seems like the more viable alternative.
- There aren’t any algae biodiesel cars just yet. While lab tests on the viability of algae fuel abound, there has been limited real-life testing. As of this writing, the one algal biodiesel car that was actually driven in a real-life setting was a Park City, Utah, Mercedes Benz E320, showcased at the January 2008 Sundance Film Festival. Stats on mileage and emissions are not available.
- Algae biodiesel has yet to be proven commercially viable. More research is needed, in order to determine if algae can actually be used on the larger scale. The technology does exist, but production is not economically efficient enough yet, and also held back by corn and grain biofuel lobbyists.
- Algae fuel might not be stable enough. Biodiesel from algae contains polyunsaturated fats, which remain fluid in colder temperatures. This, in turn, might mean that algae biodiesels are less stable in winter.
Top 5 most interesting algae biofuel companies
Location: Geraldton, Australia
The company is funded by Oak Investment Partners, Noventi, and Gabriel Venture Partners. In 2009, it successfully piloted a 6 acre system and a strain of algae whose productivity it managed to double over the course of 18 months. As of this writing, the company was looking to expand to 250 acres.
Location: Southern New Mexico
The company has successfully tested algae biofuel on jets and cars. It operates a 100-acre facility in New Mexico, as well as a 300-acre algal bio-refinery. By 2025, it plans to up its output to 1 billion gallons—although there is no official data on how much their facility is currently producing.
Image source: SDCAB
This company runs a smaller facility, spanning across no more than 5 acres, on open ponds where it grows microalgae. The facility produces 23kg of micro-algae on a daily basis. The company was founded in 2003, initiated its pilot project in 2005, and teamed up with NASA in 2011, to find more efficient ways to cultivate microalgae.
Location: Sonoran Desert (Mexico)
The aim of this company is to sell ethanol fuel harvested in algae farms for $3/gallon. To this end, they have invested $850 million. Their process seeks to slash turnaround times by harvesting the oil directly from the living algae. According to company statements, this produces a yearly yield of 6,000 gallons/acre/year.
Location: South San Francisco
Solazyme custom-creates algae cultures by mixing several DNA strains, in order to obtain the best species in terms of size and oil yield. The company uses the process of fermentation and first tested its algae oil on a jet at the end of 2008.