1. Biofuel Spotlight: Algae
Vanessa Ferrero
Jonathan Kelman
Energy Science
December 13, 2014

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What are Algae Biofuels?
More than 100,000 different species of plantlike organisms belong to the algae family,
and they can grow in massive amounts under the right conditions—all they need is water,
sunlight, and carbon dioxide [1]. Although it’s a very tiny organism, algae provide more than a
third of the oxygen we breathe, with a huge planetary impact [2]. Half of algae’s composition, by
weight, is lipid oil [1]; for some species oil can be as much as 70% of their dry weight [3]. This
oil can be made into algae biodiesel, which can be used by a regular diesel engine to run a car, or
even be turned into jet fuel [4].
The first step to making algae biodiesel is to grow the algae, generally either in an open
pond system or in a photobioreactor (see Fig. 1) [5]. Open-pond growing is the most natural way
to grow algae: you simply put large ponds in hot, sunny areas of the world in order to get the
most algae production [1]. A photobioreactor, on the other hand, places algae in clear plastic
bags so that they can be exposed to sunlight on both sides [1]. The bags are stacked high, and the
increased sun exposure increases the productivity rate of the algae while the closed system
protects the algae from contamination [1]. Photobioreactors can also be referred to as vertical
growth, or closed loop production, due to their components [1]. Though these are the two main
methods so far to produce algae, some other processes are also being looked at.
Figure 1: The algae to oil process [1].

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One is closed-tank bioreactor plants. In these plants, algae are grown in large, round
drums indoors in a facility that controls their ideal growing conditions [1]. Another method is
known as fermentation. Here algae are cultivated in closed containers and fed sugar in order to
promote their growth [1]. A final, newer idea puts a spin on the traditional photobioreactor
design. Although photobioreactors help prevent contamination, the increased exposure to light
also increases the heat in the system [3]. In order to keep the algae from “cooking”,
photobioreactors require mixing, circulating, and cleaning to be kept at the right temperatures
(this also tends to increase the costs for these systems) [3]. Jonathan Trent, a researcher at
NASA, developed a design to help lower these costs, especially for coastal cities. His idea:
Offshore Membrane Enclosures for Growing Algae (OMEGA) [3]. The concept is to take
photobioreactors made from cheap, flexible plastic tubes and have them float offshore to grow
algae [3]. By doing this, the temperature environment can be better controlled, since the tubes
can be raised or lowered in the ocean for optimal conditions [3]. In 2012, two years of OMEGA
research backed by NASA and the California Energy Commission had been underway, and the
group was planning their first full-scale run [3]. And in August of this year, a company
completed a demo run on a plant that deploys floating photobioreactors in Mobile Bay at
Daphne, Alabama [6].
Another interesting factor with the production of algae biofuels is the control over the
type algae being produced. Some algae are better for biodiesel than others (i.e. they have more
oil in them), and some algae grow faster than others. Because of this, scientists have been
working to create new strands of fast-growing, oily algae [7]. Known as “superalgae”, these
strands should be “highly efficient at converting sunlight and carbon dioxide into lipids and oils”
[7]. At Sapphire Energy, many different strains are being developed and grown in parallel tubes,

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but only the fastest-growing will move on to further development [7]. Synthetic Genomics,
another company, is also engineering synthetic algae that can produce up to 20,000 gallons of
fuel per acre—as their head Craig Venter states, it’s a matter of finding the “secret sauce” to
produce the greatest yield [8]. Phycal, another algae company, is taking a different approach to
the genetic engineering of algae. Instead of making faster-growing strains, they are trying to
develop an alga that captures less light [7]. Currently, algae capture more light than they need
and so a lot of it is wasted as heat; if they instead captured less, then more organisms could grow
from the same amount of light and this would increase production [7].
Once the algae have grown, they must be harvested in order to be made into oil. There
are many methods to do this, all with the goal of separating the algae from the rest of the water
(the cultivation media). Ultrasonic harvesting applies an acoustic wave through the system to
gently combine algal cells and promote sedimentation [9]. Another option is cross-flow
membrane filtration, which uses novel ceramic-coated membrane sheets with pore structures and
properties engineered specifically for algal harvesting [9]. Electrolytic aggregation applies a
charge to the algal cells, which forces them to collect and precipitate out of the water [9].
Researchers in England have also found a way to produce microbubbles that will allow the algae
to float to the surface for easier harvesting [8].
Although the growing conditions and harvesting are important, the integral part of biofuel
production is the actual step that turns the biomass (in this case, algae) and makes it into
biodiesel. Like with all the other steps, there are many ways to extract the oil from the algae. The
oil press, similar to an olive press, is the simplest and most common way to do this, and it can
extract up to 75% of the oil from the algae [1]. Another process, known as the hexane solvent
method, takes the leftover pressed algae, mixes it with hexane, and then filters and cleans it [1].

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This extracts up to 95% of the oil from the algae [1]. The supercritical fluids method, however, is
able to extract up to 100% of the oil from algae [1]. This method uses carbon dioxide as a
supercritical fluid (pressurized and heated to be both a liquid and a gas) and mixes it with the
algae [1]. Once they’re combined, the carbon dioxide turns the algae completely into oil, but the
extra equipment and work involved in this method make it one of the least popular options [1].
Turning algae into a biofuel isn’t difficult, but it’s also not particularly easy. However,
there are many applications to biodiesel that make the process worth it. The main use for
biodiesel is to replace diesel fuel [10]. Rudolph Diesel’s first engine was actually run on peanut
oil—it wasn’t until later that petroleum diesel fuel began to be used [10]. Using biodiesel is a
way to go back to the roots of the diesel engine, and biodiesel can be used in current diesel
engines with some slight retrofitting [10]. Biodiesel can also be used to make petroleum-based
gas, and even jet fuel [11]. Yet with the new technology being developed, costs, and time being
spent on algae biofuels we must stop to ask ourselves: are they really better than the alternative?
Algae vs. Petroleum
There are quite a few differences between the production of algae for fuel and the drilling
for petroleum, but the main argument for using algae (and biofuels in general) is that it is
essentially carbon neutral [12]. The fuel itself still has carbon emissions, but because it was
derived from a plant the carbon emitted when it is burned had just been recently absorbed as
food while the plant was growing [12]. In other words, the net CO2 emissions are as if the plant
had never grown (the carbon dioxide was absorbed by the plant, but then released by the fuel)
[12]. This claim doesn’t account for the carbon dioxide used during the production of biofuels,
but this has also been looked into [12]. When the whole process is accounted for, algae-based
biodiesel “has a GHG footprint that is 93 percent less than conventional diesel” [12]. As the

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world continues to look for ways to reduce greenhouse gas emissions and be more sustainable,
biofuels look better and better next to oil.
Algae vs. Biofuels
While biofuels are better than oil, they can come from many sources, and we have to
consider all the options before deciding that algae biofuels are “the best”. One of the biggest
concerns algae tackles is the “food vs. fuel” debate. Fuels made from plants that would otherwise
be eaten by people or livestock are known as “first generation biofuels”, and they have their
downsides [13]. Ethanol is an alcoholic biofuel distilled from sugary or starchy plants, such as
corn and sugarcane; biodiesel is made from vegetable fats [13]. With ethanol production
accounting for 40% of America’s corn harvest, it’s clear that biofuels have had an impact on
food production [13]. The argument against these first-generation biofuels is that “as the planet’s
population and demand for food grows, it becomes more unconscionable for the wealthier
nations to waste food products like corn, soy, sugar cane,… as well as food cultivation space, on
filling their gas tanks” [11]. Alga, on the other hand, isn’t a food product and it doesn’t require as
much land as the traditional fuel feedstock. Soybeans and corn require arable land, but algae can
be produced in areas unsuitable for agriculture [14].
Another thing to consider when choosing a feedstock is the growth rate of the plant. Alga
grows faster than corn and can be harvested multiple times a year [15]. Because of this, an acre
of algae can produce around 2,500 gallons of biofuel per year, whereas an acre of corn can only
make around 330 gallons [14, 15]. The U.S. Department of Energy estimates that “scaling up
algae fuel production to meet the country’s day-to-day oil consumption would take up about
15,000 square miles of land, roughly the size of a small state like Maryland [16]. In comparison,
replacing just diesel with biodiesel from soybeans and corn would require half of the nation’s
land mass to be used for soybean and corn production [16].

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The water requirement of biofuels is something that is often seen as a downside, but this
only really applies to first generation biofuels. Algae-based fuel is known as a “third generation
biofuel” since it doesn’t come from a feedstock used for human consumption, and has very low
land and water input requirements [10]. Although algae require more water to grow, this doesn’t
have to be freshwater [11]. Saltwater algae can thrive in desert ponds using high-saline water
from aquifers that couldn’t otherwise be used for traditional crops [11]. But the real advantage
to algae is that they can be grown in wastewater and used to treat it [11]. Wastewater provides a
growth medium for the algae and the algae clean the wastewater by removing nutrients and
pollutants from it [3]. Because of this, many algae ponds and cultivation facilities are located as
close as possible to wastewater treatment plants [11]. As a program started last year in Spain
stated, this “new approach to bioenergy means that Spain's 40 million population could power
200,000 vehicles every year with a single toilet flush” [17]. Alga doesn’t compete for fresh water
use, doesn’t need to rely on synthetic fertilizer, and has environmental benefits [3].
A final advantage of using algae as a feedstock is its need for concentrated carbon
dioxide to grow [10]. One unit of algal biomass requires twice that amount in carbon dioxide to
sustain commercially viable production levels: this can’t be done with atmospheric carbon
dioxide alone [10]. One of the most enticing ideas to provide these amounts of carbon dioxide is
to take carbon emissions from coal-fired power plants and use them to grow algae [10]. Because
of their high carbon dioxide needs, many algae biodiesel manufacturers are located near energy
manufacturing plants that produce a lot of carbon dioxide, and recycling this CO2 helps reduce
pollution [1].
Drawbacks and Barriers
Though there are many advantages to algae biofuels, there are also drawbacks, and
barriers to implementing it on a wider scale. One of the biggest challenges is the cost of

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producing algae biofuels. The current price of algae biocrude oil is at $7.50 a gallon, which is
more expensive than gasoline [9]. In charge of lowering the costs: the National Alliance for
Advanced Biofuels and BioProducts (NAABB). Although the $7.50/gallon price may seem steep
to some, it’s important to note that the price was originally set at $240/gallon, and NAABB was
able to reduce it to $7.50 in just three years [9]. The advancements made to reduce these costs
include new strain development, improved cultivation, and low energy harvesting technology
[9]. As the president of Genifuel, James Oyler, says, “it's a formidable challenge, to make a
biofuel that is cost-competitive with established petroleum-based fuels” [16]. NAABB continues
to work to get the price down to $3.00 a gallon [9]. This is crucial to getting algae biofuels to be
widely used, because “when it comes down to it, Americans aren't like Europeans who tend to
care more about reducing their carbon footprint…the driving force for adopting any kind of fuel
is ultimately whether it's as cheap as the gasoline we're using now” [16].
Another issue with producing algae biofuels is that it requires phosphorus as a fertilizer,
and we’re about to reach the peak of availability of Earth’s phosphate resources [11]. According
to some researchers, Earth’s phosphorus reserves are expected to be completely depleted within
50 to 100 years, and peak phosphorus (the point at which the maximum global production rate is
achieved) will be reached by 2030 [11]. In order for algae production to be viable in the long
term, it needs to reduce its use of phosphorus [11]. Algae’s phosphorus consumption is seen by
some to be its “Achilles Heel” [11].
The final problem with algae biofuels is the time it takes to produce them. “Many current
producers of algae biofuel dry the algae first and then extract the natural oil, which adds time and
expense to the process” [8]. However, researchers continue to work on expediting the extraction
process in order to produce algae biofuels faster. The Pacific Northwest National Laboratory has

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found a way to speed up the “cooking process” to the point where a small mixture of algae and
water can be turned into crude oil in less than an hour [16]. Given 100 pounds of algae feedstock,
their system can produce 53 pounds of bio-oil, which is chemically similar to light, sweet crude
[16]. The process basically involves an extreme pressure cooker kept at a high temperature,
which does require quite a bit of energy—but the researchers point out that the system has heat
recovery features that cycle it back into the process to minimize losses [16]. The chemical
reaction also leaves behind compounds such as hydrogen, oxygen, and carbon dioxide, which
can be used to make natural gas, and minerals like nitrogen, phosphorus, and potassium can be
reused as fertilizer [16]. If this technique is scaled up, companies could sell biofuel for as little as
$2.00 a gallon [16]. This would not only make the process faster, but also make the end product
cheaper, fixing two problems at once. Reusing the phosphorus left over is also a good way to
begin to tackle the phosphorus issue.
If an hour still seems like too long to wait for algae biofuel, another group is working to
make it in as little as a minute [8]. At the University of Michigan, scientists fill a steel pipe
connector with 1.5mL of wet algae, cap it, and immerse it in 1,100F sand [8]. By doing this,
they “mimic the process in nature that forms crude oil with marine organisms” and are able to
transform 65% of the algae into biocrude, which contains 90% of the energy in the original algae
[8]. Though this experiment only uses a small amount of algae at a time, it could be quite
revolutionary if it is scaled up to the amounts needed to displace petroleum.
Future Prospects
Experts estimate that it will take 140 billion gallons of algae biodiesel each year to
replace petroleum-based products [1]. As stated earlier, U.S. daily oil consumption could be
replaced with algae biofuel growing on land the size of a state like Maryland [16]. We know that

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using biodiesel from algae is a better option than making bioethanol from corn and sugar due to
the large amounts of land, time, and freshwater required for the latter. Because of all the reasons
pushing us towards algae biofuels, I think the main reasons holding us back are the cost and
unfamiliarity of algae.
The familiarity issue simply arises from the fact that we’ve spent over 150 years building
a massive infrastructure, ideology, and industry around oil [18]. Oil is something everyone is
familiar with and used to, and people are generally very resistant to change. Easing biofuels, and
especially algae biodiesel, into the market will probably take some time and marketing, but at the
same time any resistance to it will be greatly minimized by its low cost. Though the cost is still at
$7.50/gallon, a lot of new technologies could bring it down to two or even three dollars a gallon.
This would definitely push the transition to algae biofuel, and our primary transportation fuel
industry would slowly change from petroleum to algae biodiesel. New cars would come out to
run on biodiesel, and older diesel engines could be upgraded to run on biodiesel as well.
The main driving factors for making the change to biodiesel are the reduction in carbon
dioxide emissions and the necessity for finding a new fuel source other than oil. Biofuels are
essentially carbon neutral, which is a much-needed change from our current carbon dioxide
emitting fuel-of-choice: oil. Because the world oil supply is limited, we can’t plan on using it as
a fuel source forever, especially with the cost of production rising as we have to resort to more
and more unconventional methods in order to feed our oil dependency. It would be best to make
the switch sooner rather than later, as greenhouse gas emissions and climate change continue to
rise. While we could wait until we have no other options, hopefully we begin to make the switch
to biofuels or other options (hybrids, electric cars, etc.) soon. As biofuels become more cost-
competitive, it is likely that we’ll start making the switch in the coming years, public support and

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policy providing. The U.S. Department of Energy recently gave a $15 million grant to establish
an algae biofuel test bed in Arizona, and NASA has also launched an algae biofuel initiative, so
it seems government support for the fuel is growing [8].
Algae-based fuels are appealing because they address a lot of the problems faced by other
alternative energy sources. They aren’t hazardous like nuclear fuel, they are biodegradable unlike
solar panels, and they don’t compete with food supplies as other biofuels do [16]. Because of all
of the advantages of using it as a fuel, algae-based biodiesel will likely become an important,
widespread transportation fuel, though this likely won’t be until its costs are lower than that of
gasoline. “The balance might change as oil becomes scarcer, or if carbon emissions are taxed,
but recent estimates suggest algae biofuels will struggle to compete on price” [19]. However, we
can’t count on these things to happen fast enough to get us to switch over; a better bet is for the
NAABB to find newer technologies to reach their goal of $3/gallon as quickly as possible. Only
time will tell how long it will be before this happens, but given their ability to go from $240 to
$7.5/gallon in only three years, hopes are high that they’ll be able to reach their target quickly.

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