Algae fuel or algal biofuel is an alternative to fossil fuel
that uses algae as its source of natural deposits. Several companies and
government agencies are funding efforts to reduce capital and operating costs
and make algae fuel production commercially viable. Like fossil fuel, algae
fuel releases CO
2 when burnt, but unlike fossil fuel, algae fuel and other
biofuels only release CO
2 recently removed from the atmosphere via photosynthesis as
the algae or plant grew. The energy crisis and the world food crisis have
ignited interest in algaculture (farming algae) for making biodiesel and other
biofuels using land unsuitable for agriculture. Among algal fuels' attractive
characteristics are that they can be grown with minimal impact on fresh water
resources, can be produced using saline and wastewater, have a high flash
point, and are biodegradable and relatively harmless to the environment if
spilled. Algae cost more per unit mass than other second-generation biofuel
crops due to high capital and operating costs,[8] but are claimed to yield
between 10 and 100 times more fuel per unit area.The United States Department
of Energy estimates that if algae fuel replaced all the petroleum fuel in the
United States, it would require 15,000 square miles (39,000 km2), which is only
0.42% of the U.S. map, or about half of the land area of Maine. This is less
than 1⁄7 the area of corn harvested in the United States in 2000.
According to the head of the Algal Biomass Organization,
algae fuel can reach price parity with oil in 2018 if granted production tax
credits. However, in 2013, Exxon Mobil Chairman and CEO Rex Tillerson said that
after committing to spend up to $600 million over 10 years on development in a
joint venture with J. Craig Venter’s Synthetic Genomics in 2009, Exxon pulled
back after four years (and $100 million) when it realized that algae fuel is
"probably further" than 25 years away from commercial viability. On
the other hand, Solazyme and Sapphire Energy already began commercial sales of
algal biofuel in 2012 and 2013, respectively, and Algenol hopes to produce
commercially in 2014.
History
In 1942 Harder and von Witsch were the first to propose that
microalgae be grown as a source of lipids for food or fuel. Following World War
II, research began in the US, Germany, Japan, England, and Israe on culturing
techniques and engineering systems for growing microalgae on larger scales,
particularly species in the genus Chlorella. Meanwhile, Aach showed that
Chlorella pyrenoidosa could be induced via nitrogen starvation to accumulate as
much as 70% of its dry weight as lipids. Since the need for alternative
transportation fuel had subsided after World War II, research at this time
focused on culturing algae as a food source or, in some cases, for wastewater
treatment.
Interest in the application of algae for biofuels was
rekindled during the oil embargo and oil price surges of the 1970s, leading the
US Department of Energy to initiate the Aquatic Species Program in 1978. The
Aquatic Species Program spent $25 million over 18 years with the goal of
developing liquid transportation fuel from algae that would be price
competitive with petroleum-derived fuels. The research program focused on the
cultivation of microalgae in open outdoor ponds, systems which are low in cost
but vulnerable to environmental disturbances like temperature swings and
biological invasions. 3,000 algal strains were collected from around the
country and screened for desirable properties such as high productivity, lipid
content, and thermal tolerance, and the most promising strains were included in
the SERI microalgae collection at the Solar Energy Research Institute in
Golden, Colorado and used for further research. Among the program’s most
significant findings were that rapid growth and high lipid production were
“mutually exclusive,” since the former required high nutrients and the latter
required low nutrients. The final report suggested that genetic engineering may
be necessary to be able to overcome this and other natural limitations of algal
strains, and that the ideal species might vary with place and season. Although
it was successfully demonstrated that large-scale production of algae for fuel
in outdoor ponds was feasible, the program failed to do so at a cost that would
be competitive with petroleum, especially as oil prices sank in the 1990s. Even
in the best case scenario, it was estimated that unextracted algal oil would
cost $59–186 per barrel, while petroleum cost less than $20 per barrel in 1995.
Therefore, under budget pressure in 1996, the Aquatic Species Program was
abandoned.
Other contributions to algal biofuels research have come
indirectly from projects focusing on different applications of algal cultures.
For example, in the 1990s Japan’s Research Institute of Innovative Technology
for the Earth (RITE) implemented a research program with the goal of developing
systems to fix CO
2 using microalgae.[30] Although the goal was not energy
production, several studies produced by RITE demonstrated that algae could be
grown using flue gas from power plants as a CO
2 source, an important development for algal biofuel
research. Other work focusing on harvesting hydrogen gas, methane, or ethanol
from algae, as well as nutritional supplements and pharmaceutical compounds,
has also helped inform research on biofuel production from algae.
Following the disbanding of the Aquatic Species Program in
1996, there was a relative lull in algal biofuel research. Still, various
projects were funded in the US by the Department of Energy, Department of
Defense, National Science Foundation, Department of Agriculture, national
laboratories, state funding, and private funding, as well as in other
countries. More recently, rising oil prices in the 2000s spurred a revival of
interest in algal biofuels and US federal funding has increased,[28] numerous
research projects are being funded in Australia, New Zealand, Europe, the
Middle East, and other parts of the world, and a wave of private companies has
entered the field (see Companies). In November 2012, Solazyme and Propel Fuels
made the first retail sales of algae-derived fuel, and in March 2013 Sapphire
Energy began commercial sales of algal biofuel to Tesoro.
Fuels
Algae can be converted into various types of fuel, depending
on the technique and the part of the cells used. The lipid, or oily part of the
algae biomass can be extracted and converted into biodiesel through a process
similar to that used for any other vegetable oil, or converted in a refinery
into "drop-in" replacements for petroleum-based fuels. Alternatively
or following lipid extraction, the carbohydrate content of algae can be
fermented into bioethanol or biobutanol.
Biodiesel
Biodiesel is a diesel fuel derived from animal or plant
lipids (oils and fats). Studies have shown that some species of algae can
produce 60% or more of their dry weight in the form of oil. Because the cells
grow in aqueous suspension, where they have more efficient access to water, CO
2 and dissolved nutrients, microalgae are capable of
producing large amounts of biomass and usable oil in either high rate algal
ponds or photobioreactors. This oil can then be turned into biodiesel which
could be sold for use in automobiles. Regional production of microalgae and
processing into biofuels will provide economic benefits to rural communities.
As they do not have to produce structural compounds such as
cellulose for leaves, stems, or roots, and because they can be grown floating
in a rich nutritional medium, microalgae can have faster growth rates than
terrestrial crops. Also, they can convert a much higher fraction of their
biomass to oil than conventional crops, e.g. 60% versus 2-3% for soybeans. The
per unit area yield of oil from algae is estimated to be from 58,700 to 136,900
L/ha/year, depending on lipid content, which is 10 to 23 times as high as the
next highest yielding crop, oil palm, at 5,950 L/ha/year.
The U.S. Department of Energy's Aquatic Species Program,
1978–1996, focused on biodiesel from microalgae. The final report suggested
that biodiesel could be the only viable method by which to produce enough fuel
to replace current world diesel usage. If algae-derived biodiesel were to
replace the annual global production of 1.1bn tons of conventional diesel then
a land mass of 57.3 million hectares would be required, which would be highly
favorable compared to other biofuels.
Biobutanol
Butanol can be made from algae or diatoms using only a solar
powered biorefinery. This fuel has an energy density 10% less than gasoline,
and greater than that of either ethanol or methanol. In most gasoline engines,
butanol can be used in place of gasoline with no modifications. In several
tests, butanol consumption is similar to that of gasoline, and when blended
with gasoline, provides better performance and corrosion resistance than that
of ethanol or E85.
The green waste left over from the algae oil extraction can
be used to produce butanol. In addition, it has been shown that macroalgae
(seaweeds) can be fermented by Clostridia genus bacteria to butanol and other
solvents.
Biogasoline
Biogasoline is gasoline produced from biomass. Like
traditionally produced gasoline, it contains between 6 (hexane) and 12
(dodecane) carbon atoms per molecule and can be used in internal-combustion
engines.
Methane
Methane, the main constituent of natural gas can be produced
from algae in various methods, namely Gasification, Pyrolysis and Anaerobic
Digestion. In Gasification and Pyrolysis methods methane is extracted under
high temperature and pressure. Anaerobic Digestion is a straight forward method
involved in decomposition of algae into simple components then transforming it
into fatty acids using microbes like acidific bacteria followed by removing any
solid particles and finally adding methanogenic bacteria to release a gas
mixture containing methane. A number of studies have successfully shown that
biomass from microalgae can be converted into biogas via anaerobic digestion.
Therefore, in order to improve the overall energy balance of microalgae
cultivation operations, it has been proposed to recover the energy contained in
waste biomass via anaerobic digestion to methane for generating electricity.
Ethanol
The Algenol system which is being commercialized by
BioFields in Puerto Libertad, Sonora, Mexico utilizes seawater and industrial
exhaust to produce ethanol. Porphyridium cruentum also have shown to be
potentially suitable for ethanol production due to its capacity for
accumulating large amount of carbohydrates.
Hydrocracking to traditional transport fuels
Algae can be used to produce 'green diesel' (also known as
renewable diesel, hydro-treated vegetable oil or hydrogen-derived renewable
diesel) through a hydrocracking refinery process that breaks molecules down
into shorter hydrocarbon chains used in diesel engines. It has the same
chemical properties as petroleum-based diesel meaning that it does not require
new engines, pipelines or infrastructure to distribute and use. It has yet to
be produced at a cost that is competitive with petroleum.
Jet fuel
Rising jet fuel prices are putting severe pressure on airline
companies, creating an incentive for algal jet fuel research. The International
Air Transport Association, for example, supports research, development and
deployment of algal fuels. IATA's goal is for its members to be using 10%
alternative fuels by 2017.
Trials have been carried with aviation biofuel by Air New
Zealand,[60] Lufthansa, and Virgin Airlines.
In February 2010, the Defense Advanced Research Projects
Agency announced that the U.S. military was about to begin large-scale oil
production from algal ponds into jet fuel. After extraction at a cost of $2 per
gallon, the oil will be refined at less than $3 a gallon. A larger-scale
refining operation, producing 50 million gallons a year, is expected to go into
production in 2013, with the possibility of lower per gallon costs so that
algae-based fuel would be competitive with fossil fuels. The projects, run by
the companies SAIC and General Atomics, are expected to produce 1,000 gallons
of oil per acre per year from algal ponds.
Species
Research into algae for the mass-production of oil focuses
mainly on microalgae (organisms capable of photosynthesis that are less than
0.4 mm in diameter, including the diatoms and cyanobacteria) as opposed to
macroalgae, such as seaweed. The preference for microalgae has come about due
largely to their less complex structure, fast growth rates, and high
oil-content (for some species). However, some research is being done into using
seaweeds for biofuels, probably due to the high availability of this resource.
As of 2012 researchers across various locations worldwide
have started investigating the following species for their suitability as a
mass oil-producers:
Botryococcus
braunii
Chlorella
Dunaliella
tertiolecta
Gracilaria
Pleurochrysis
carterae (also called CCMP647).[68]
Sargassum, with 10
times the output volume of Gracilaria.
The amount of oil each strain of algae produces varies
widely. Note the following microalgae and their various oil yields:
Ankistrodesmus
TR-87: 28–40% dw
Botryococcus
braunii: 29–75% dw
Chlorella sp.:
29%dw
Chlorella
protothecoides(autotrophic/ heterothrophic): 15–55% dw
Cyclotella DI- 35:
42%dw
Dunaliella
tertiolecta : 36–42%dw
Hantzschia DI-160:
66%dw
Nannochloris:
31(6–63)%dw
Nannochloropsis :
46(31–68)%dw
Nitzschia TR-114:
28–50%dw
Phaeodactylum
tricornutum: 31%dw
Scenedesmus TR-84:
45%dw
Stichococcus:
33(9–59)%dw
Tetraselmis
suecica: 15–32%dw
Thalassiosira
pseudonana: (21–31)%dw
Crypthecodinium
cohnii: 20%dw
Neochloris
oleoabundans: 35–54%dw
Schiochytrium
50–77%dw[70]
In addition, due to its high growth-rate, Ulva has been
investigated as a fuel for use in the SOFT cycle, (SOFT stands for Solar Oxygen
Fuel Turbine), a closed-cycle power-generation system suitable for use in arid,
subtropical regions.
Algae cultivation
Algae grow much faster than food crops, and can produce
hundreds of times more oil per unit area than conventional crops such as
rapeseed, palms, soybeans, or jatropha. As algae have a harvesting cycle of
1–10 days, their cultivation permits several harvests in a very short
time-frame, a strategy differing from that associated with annual crops. In
addition, algae can be grown on land unsuitable for terrestrial crops,
including arid land and land with excessively saline soil, minimizing competition
with agriculture. Most research on algae cultivation has focused on growing
algae in clean but expensive photobioreactors, or in open ponds, which are
cheap to maintain but prone to contamination.
Photobioreactors
Photobioreactor from glass tubes
Most companies pursuing algae as a source of biofuels pump
nutrient-rich water through plastic or borosilicate glass tubes (called
"bioreactors" ) that are exposed to sunlight (and so-called
photobioreactors or PBR).
Running a PBR is more difficult than using an open pond, and
more costly, but may provide a higher level of control and productivity.
Algae farms can also operate on marginal lands, such as in
desert areas where the groundwater is saline, rather than utilizing fresh
water. Algae can also grow on the surface of the ocean.
Because algae strains with lower lipid content may grow as
much as 30 times faster than those with high lipid content, the challenges in
efficient biodiesel production from algae lie in finding an algal strain with a
combination of high lipid-content and fast growth-rate, not too difficult to harvest;
and with a cost-effective cultivation system (i.e., type of photobioreactor)
best suited to that strain.
Closed-loop system
The lack of equipment and structures needed to begin growing
algae in large quantities has inhibited widespread mass-production of algae for
biofuel production. Maximum use of existing agriculture processes and hardware
is the goal.
Closed systems (not exposed to open air) avoid the problem
of contamination by other organisms blown in by the air. The problem for a
closed system is finding a cheap source of sterile CO
2. Several experimenters have found the CO
2 from a smokestack works well for growing algae. For
reasons of economy, some experts think that algae farming for biofuels will
have to be done as part of cogeneration, where it can make use of waste heat
and help soak up pollution.
Open pond
Raceway pond used for the cultivation of microalgae
Open-pond systems for the most part have been given up for
the cultivation of algae with especially high oil content.Many[who?] believe
that a major flaw of the Aquatic Species Program was the decision to focus
their efforts exclusively on open-ponds; this makes the entire effort dependent
upon the hardiness of the strain chosen, requiring it to be unnecessarily
resilient in order to withstand wide swings in temperature and pH, and
competition from invasive algae and bacteria. Open systems using a monoculture
are also vulnerable to viral infection. The energy that a high-oil strain
invests into the production of oil is energy that is not invested into the
production of proteins or carbohydrates, usually resulting in the species being
less hardy, or having a slower growth rate. Algal species with a lower oil
content, not having to divert their energies away from growth, can be grown
more effectively in the harsher conditions of an open system.
Some open sewage-ponds trial production has taken place in
Marlborough, New Zealand.
Fuel production
Turning wet algal biomass into combustible fuel has proven challenging.
After harvesting the algae, the biomass is typically processed in a series of
steps, which can differ based on the species and desired product; this is an
active area of research. Often, the algae is dehydrated and then a solvent such
as hexane is used to extract energy-rich compounds like triglycerides from the
dried material.[89] Then, the extracted compounds can be processed into fuel
using standard industrial procedures. For example, the extracted triglycerides
are reacted with methanol to create biodiesel via transesterification. The
unique composition of fatty acids of each species influences the quality of the
resulting biodiesel and thus must be taken into account when selecting algal
species for feedstock.
High temperature and pressure
An alternative approach employs a continuous process that
subjects harvested wet algae to high temperatures and pressures—350 °C (662 °F)
and 3,000 pounds per square inch (21,000 kPa).
Products include crude oil, which can be further refined
into aviation fuel, gasoline, or diesel fuel. The test process converted
between 50 and 70 percent of the algae’s carbon into fuel. Other outputs
include clean water, fuel gas and nutrients such as nitrogen, phosphorus, and
potassium.
Nutrients
Nutrients like nitrogen (N), phosphorus (P), and potassium
(K), are important for plant growth and are essential parts of fertilizer.
Silica and iron, as well as several trace elements, may also be considered important
marine nutrients as the lack of one can limit the growth of, or productivity
in, an area.
Carbon dioxide
Bubbling CO
2 through algal cultivation systems can greatly increase
productivity and yield (up to a saturation point). Typically, about 1.8 tonnes
of CO
2 will be utilised per tonne of algal biomass (dry)
produced, though this varies with algae species. The Glenturret Distillery in
Perthshire, UK – home to The Famous Grouse Whisky – percolate CO
2 made during the whisky distillation through a microalgae
bioreactor. Each tonne of microalgae absorbs two tonnes of CO
2. Scottish Bioenergy, who run the project, sell the
microalgae as high value, protein-rich food for fisheries. In the future, they
will use the algae residues to produce renewable energy through anaerobic
digestion.
Nitrogen
Nitrogen is a valuable substrate that can be utilized in
algal growth. Various sources of nitrogen can be used as a nutrient for algae,
with varying capacities. Nitrate was found to be the preferred source of
nitrogen, in regards to amount of biomass grown. Urea is a readily available
source that shows comparable results, making it an economical substitute for
nitrogen source in large scale culturing of algae. Despite the clear increase
in growth in comparison to a nitrogen-less medium, it has been shown that
alterations in nitrogen levels affect lipid content within the algal cells. In
one study nitrogen deprivation for 72
hours caused the total fatty acid content (on a per cell basis) to increase by
2.4-fold. 65% of the total fatty acids were esterified to triacylglycerides in
oil bodies, when compared to the initial culture, indicating that the algal
cells utilized de novo synthesis of fatty acids. It is vital for the lipid
content in algal cells to be of high enough quantity, while maintaining
adequate cell division times, so parameters that can maximize both are under
investigation.
Wastewater
A possible nutrient source is waste water from the treatment
of sewage, agricultural, or flood plain run-off, all currently major pollutants
and health risks. However, this waste water cannot feed algae directly and must
first be processed by bacteria, through anaerobic digestion. If waste water is
not processed before it reaches the algae, it will contaminate the algae in the
reactor, and at the very least, kill much of the desired algae strain. In
biogas facilities, organic waste is often converted to a mixture of carbon
dioxide, methane, and organic fertilizer. Organic fertilizer that comes out of
the digester is liquid, and nearly suitable for algae growth, but it must first
be cleaned and sterilized.
The utilization of wastewater and ocean water instead of
freshwater is strongly advocated due to the continuing depletion of freshwater
resources. However, heavy metals, trace metals, and other contaminants in
wastewater can decrease the ability of cells to produce lipids biosynthetically
and also impact various other workings in the machinery of cells. The same is
true for ocean water, but the contaminants are found in different
concentrations. Thus, agricultural-grade fertilizer is the preferred source of
nutrients, but heavy metals are again a problem, especially for strains of
algae that are susceptible to these metals. In open pond systems the use of
strains of algae that can deal with high concentrations of heavy metals could
prevent other organisms from infesting these systems. In some instances it has
even been shown that strains of algae can remove over 90% of nickel and zinc
from industrial wastewater in relatively short periods of time.
Environmental impact
In comparison with terrestrial-based biofuel crops such as
corn or soybeans, microalgal production results in a much less significant land
footprint due to the higher oil productivity from the microalgae than all other
oil crops. Algae can also be grown on marginal lands useless for ordinary crops
and with low conservation value, and can use water from salt aquifers that is
not useful for agriculture or drinking. Thus microalgae could provide a source
of clean energy with little impact on the provisioning of adequate food and
water or the conservation of biodiversity.Algae cultivation also requires no
external subsidies of insecticides or herbicides, removing any risk of
generating associated pesticide waste streams. Furthermore, compared to fuels
like diesel and petroleum, the combustion of algal biofuel does not produce any
sulfur oxides, and produces a reduced amount of carbon monoxide, unburned
hydrocarbons, and reduced emission of harmful pollutants. Finally, algal
biofuel consists of safe, natural compounds that represent little to no
environmental risk if spilled, in contrast with fossil fuels[citation needed].
Studies have determined that replacing fossil fuels with
renewable energy sources, such as biofuels, have the capability of reducing CO
2 emissions by up to 80%. Since terrestrial plant sources of
biofuel production simply do not have the production capacity to meet current
energy requirements, microalgae may be one of the only options to approach
complete replacement of fossil fuels. An algae-based system could capture
approximately 80% of the CO
2 emitted from a power plant when sunlight is available.
Although this CO
2 will later be released into the atmosphere when the fuel
is burned, this CO
2 would have entered the atmosphere regardless.The
possibility of reducing total CO
2 emissions therefore lies in the prevention of the release
of CO
2 from fossil fuels.
Microalgae production also includes the ability to use
saline waste or waste CO
2 streams as an energy source. This opens a new strategy to
produce biofuel in conjunction with wastewater treatment in order to get
reclaimed water. When used in a microalgal bioreactor, harvested microalgae
will capture significant quantities of organic compounds as well as heavy metal
contaminants absorbed from wastewater streams that would otherwise be directly
discharged into surface and ground-water. Moreover, this process also allows
the recovery of phosphorus from waste, which is an essential but scarce element
in nature – the reserves of which are estimated to have depleted in the last 50
years.
Polycultures
Nearly all research in algal biofuels has focused on
culturing single species, or monocultures, of microalgae. However, ecological
theory and empirical studies have demonstrated that plant and algae
polycultures, i.e. groups of multiple species, tend to produce larger yields
than monocultures. Experiments have also shown that more diverse aquatic
microbial communities tend to be more stable through time than less diverse communities.
Recent studies found that polycultures of microalgae produced significantly
higher lipid yields than monocultures. Polycultures also tend to be more
resistant to pest and disease outbreaks, as well as invasion by other plants or
algae. Thus culturing microalgae in polyculture may not only increase yields
and stability of yields of biofuel, but also reduce the environmental impact of
an algal biofuel industry.
Economic viability
There is clearly a demand for sustainable biofuel
production, but whether a particular biofuel will be used ultimately depends
not on sustainability but cost efficiency. If more energy goes into the fuel
than is expelled after combustion, there is no net environmental or economic
benefit. Therefore research is focusing on cutting the cost of algal biofuel
production to the point where it can compete with conventional petroleum.
In a 2007 report a formula was derived estimating the cost
of algal oil in order for it to be a viable substitute to petroleum diesel:
C(algal oil) = 25.9 × 10−3 C(petroleum)
where: C(algal oil) is the price of microalgal oil in
dollars per gallon and C(petroleum) is the price of crude oil in dollars per
barrel. This equation assumes that algal oil has roughly 80% of the caloric
energy value of crude petroleum. As of January 29 (2013), with petroleum priced
at $110.52/barrel, algal oil should cost no more than $2.86/gallon in order to
be competitive with petroleum diesel. (Note: 1 petroleum barrel = 42 US
gallons)
With current technology available it is estimated that the
cost of producing microalgal biomass is $2.95/kg for photobioreactors and
$3.80/kg for open-ponds. These estimates assume that carbon dioxide is
available at no cost. If the annual biomass production capacity is increased to
10000 tonnes, the cost of production per kilogram reduces to roughly $0.47 and
$0.60, respectively. Assuming that the biomass contains 30% oil by weight, the
cost of biomass for providing a liter of oil would be approximately $1.40 and
$1.81 for photobioreactors and raceways, respectively. Oil recovered from the
lower cost biomass produced in photobioreactors is estimated to cost $2.80/L,
assuming the recovery process contributes 50% to the cost of the final
recovered oil. If existing algae projects can achieve biodiesel production
price targets of less than $1 per gallon, the United States may realize its
goal of replacing up to 20% of transport fuels by 2020 by using environmentally
and economically sustainable fuels from algae production.
Whereas technical problems, such as harvesting, are being
addressed successfully by the industry, the high up-front investment of
algae-to-biofuels facilities is seen by many as a major obstacle to the success
of this technology. Only few studies on the economic viability are publicly
available, and must often rely on the little data (often only engineering
estimates) available in the public domain. Dmitrov examined the GreenFuels
photobioreactor and estimated that algae oil would only be competitive at an
oil price of $800 per barrel. A study by Alabi et al. examined raceways,
photobioreactors and anaerobic fermenters to make biofuels from algae and found
that photobioreactors are too expensive to make biofuels. Raceways might be
cost-effective in warm climates with very low labor costs, and fermenters may
become cost-effective subsequent to significant process improvements. The group
found that capital cost, labor cost and operational costs (fertilizer,
electricity, etc.) by themselves are too high for algae biofuels to be
cost-competitive with conventional fuels. Similar results were found by others,
suggesting that unless new, cheaper ways of harnessing algae for biofuels
production are found, their great technical potential may never become
economically accessible. Recently, Rodrigo E. Teixeira demonstrated a new
reaction and proposed a process for harvesting and extracting raw materials for
biofuel and chemical production that requires a fraction of the energy of
current methods, while extracting all cell constituents.
Use of Byproducts
Many of the byproducts produced in the processing of
microalgae can be used in various applications, many of which have a longer
history of production than algal biofuel. Some of the products not used in the
production of biofuel include natural dyes and pigments, antioxidants, and
other high-value bio-active compounds. These chemicals and excess biomass have
found numerous use in other industries. For example, the dyes and oils have
found a place in cosmetics, commonly as thickening and water-binding agents.
Discoveries within the pharmaceutical industry include antibiotics and
antifungals derived from microalgae, as well as natural health products, which
have been growing in popularity over the past few decades. For instance
Spirulina contains numerous polyunsaturated fats (Omega 3 and 6), amino acids
and vitamins, as well as pigments that may be beneficial, such as beta-carotene
and chlorophyll.
Advantages
Ease of growth
One of the main advantages that using microalgae as the
feedstock when compared to more traditional crops is that it can be grown much
more easily. Algae can be grown in land that would not be considered suitable
for the growth of the regularly used crops. In addition to this, wastewater
that would normally hinder plant growth has been shown to be very effective in
growing algae. Because of this, algae can be grown without taking up arable
land that would otherwise be used for producing food crops, and the better
resources can be reserved for normal crop production. Microalgae also require
fewer resources to grow and little attention is needed, allowing the growth and
cultivation of algae to be a very passive process.
Impact on food
Many traditional feedstocks for biodiesel, such as corn and
palm, are also used as feed for livestock on farms, as well as a valuable
source of food for humans. Because of this, using them as biofuel reduces the
amount of food available for both, resulting in an increased cost for both the
food and the fuel produced. Using algae as a source of biodiesel can alleviate
this problem in a number of ways. First, algae is not used as a primary food
source for humans, meaning that it can be used solely for fuel and there would
be little impact in the food industry. Second, many of the waste-product
extracts produced during the processing of algae for biofuel can be used as a
sufficient animal feed. This is an effective way to minimize waste and a much
cheaper alternative to the more traditional corn or grain based feeds.
Minimization of waste
Growing algae as a source of biofuel has also been shown to
have numerous environmental benefits, and has presented itself as a much more
environmentally friendly alternative to current biofuels. For one, it is able
to utilize run-off, water contaminated with fertilizers and other nutrients
that are a by-product of farming, as its primary source of water and nutrients.
Because of this, it prevents this contaminated water from mixing with the lakes
and rivers that currently supply our drinking water. In addition to this, the
ammonia, nitrates, and phosphates that would normally render the water unsafe
actually serve as excellent nutrients for the algae, meaning that fewer
resources are needed to grow the algae. Many algae species used in biodiesel
production are excellent bio-fixers, meaning they are able to remove carbon
dioxide from the atmosphere to use as a form of energy for themselves. Because
of this, they have found use in industry as a way to treat flue gases and reduce
GHG emissions.
Disadvantages
Commercial Viability
Algae biodiesel is still a fairly new technology. Despite
the fact that research began over 30 years ago, it was put on hold during the
mid-1990s, mainly due to a lack of funding and a relatively low petroleum cost.
For the next few years algae biofuels saw little attention; it was not until
the gas peak of the early 2000s that it eventually had a revitalization in the
search for alternative fuel sources. While the technology exists to harvest and
convert algae into a usable source of biodiesel, it still hasn't been
implemented into a large enough scale to support the current energy needs.
Further research will be required to make the production of algae biofuels more
efficient, and at this point it is currently being held back by lobbyists in
support of alternative biofuels, like those produced from corn and grain. In
2013, Exxon Mobil Chairman and CEO Rex Tillerson said that after originally
committing to spending up to $600 million on development in a joint venture
with J. Craig Venter’s Synthetic Genomics, algae is “probably further” than “25
years away” from commercial viability, although Solazyme and Sapphire Energy
already began small-scale commercial sales in 2012 and 2013, respectively.
Stability
The biodiesel produced from the processing of microalgae
differs from other forms of biodiesel in the content of polyunsaturated fats.Polyunsaturated
fats are known for their ability to retain fluidity at lower temperatures.
While this may seem like an advantage in production during the colder
temperatures of the winter, the polyunsaturated fats result in lower stability
during regular seasonal temperatures.
Research
Current projects
United States
US universities which are working on producing oil from
algae include: Washington State University, Oregon State University, Arizona
State University, The University of Arizona, University of Illinois at
Urbana-Champaign, University of Michigan University of California San Diego,
University of Nebraska Lincoln, University of Texas at Austin, University of
Maine, University of Kansas, The College of William and Mary, Northern Illinois
University, University of Texas at San Antonio, Old Dominion University, Utah
State University, New Mexico State University, and Missouri University of
Science and Technology.
The National Renewable Energy Laboratory (NREL) is the U.S.
Department of Energy's primary national laboratory for renewable energy and
energy efficiency research and development. This program is involved in the
production of renewable energies and energy efficiency. One of its most current
divisions are consists the biomass program which is involved in biomass
characterization, biochemical and thermochemical conversion technologies in
conjunction with biomass process engineering and analysis. The program aims at
producing energy efficient, cost-effective and environmentally friendly
technologies that support rural economies, reduce the nations dependency in oil
and improve air quality.
At the Woods Hole Oceanographic Institution and the Harbor
Branch Oceanographic Institution the wastewater from domestic and industrial
sources contain rich organic compounds that are being used to accelerate the
growth of algae. The Department of Biological and Agricultural Engineering at
University of Georgia is exploring microalgal biomass production using
industrial wastewater. Algaewheel, based in Indianapolis, Indiana, presented a
proposal to build a facility in Cedar Lake, Indiana that uses algae to treat
municipal wastewater, using the sludge byproduct to produce biofuel.
Sapphire Energy (San Diego) has produced green crude from
algae.
Solazyme (South San Francisco, California) has produced a
fuel suitable for powering jet aircraft from algae.
Europe
Universities in the United Kingdom which are working on
producing oil from algae include: University of Manchester, University of
Sheffield, University of Glasgow, University of Brighton, University of
Cambridge, University College London, Imperial College London, Cranfield
University and Newcastle University. In Spain, it is also relevant the research
carried out by the CSIC´s Instituto de Bioquímica Vegetal y Fotosíntesis
(Microalgae Biotechnology Group, Seville).
The Marine Research station in Ketch Harbour, Nova Scotia,
has been involved in growing algae for 50 years. The National Research Council
(NRC) and National Byproducts Program have provided $5 million to fund this
project. The aim of the program has been to build a 50 000 litre cultivation
pilot plant at the Ketch harbor facility. The station has been involved in
assessing how best to grow algae for biofuel and is involved in investigating
the utilization of numerous algae species in regions of North America. NRC has
joined forces with the United States Department of Energy, the National
Renewable Energy Laboratory in Colorado and Sandia National Laboratories in New
Mexico.
The European Algae Biomass Association (EABA) is the
European association representing both research and industry in the field of algae
technologies, currently with 79 members. The association is headquartered in
Florence, Italy. The general objective of the European Algae Biomass
Association (EABA) is to promote mutual interchange and cooperation in the
field of biomass production and use, including biofuels uses and all other
utilisations. It aims at creating, developing and maintaining solidarity and
links between its Members and at defending their interests at European and
international level. Its main target is to act as a catalyst for fostering
synergies among scientists, industrialists and decision makers to promote the
development of research, technology and industrial capacities in the field of
Algae.
CMCL innovations and the University of Cambridge are
carrying out a detailed design study of a C-FAST[153] (Carbon negative Fuels
derived from Algal and Solar Technologies) plant. The main objective is to
design a pilot plant which can demonstrate production of hydrocarbon fuels
(including diesel and gasoline) as sustainable carbon-negative energy carriers
and raw materials for the chemical commodity industry. This project will report
in June 2013.
Ukraine plans to produce biofuel using a special type of
algae.
The European Commission's Algae Cluster Project, funded
through the Seventh Framework Programme, is made up of three algae biofuel
projects, each looking to design and build a different algae biofuel facility
covering 10ha of land. The projects are BIOFAT, All-Gas and InteSusAl.
Since various fuels and chemicals can be produced from
algae, it has been suggested to investigate the feasibility of various
production processes( conventional extraction/separation, hydrothermal
liquefaction, gasification and pyrolysis) for application in an integrated
algal biorefinery.
Other
The Algae Biomass Organization (ABO)[157] is a non-profit
organization whose mission is "to promote the development of viable
commercial markets for renewable and sustainable commodities derived from
algae".
The National Algae Association (NAA) is a non-profit
organization of algae researchers, algae production companies and the
investment community who share the goal of commercializing algae oil as an
alternative feedstock for the biofuels markets. The NAA gives its members a
forum to efficiently evaluate various algae technologies for potential early
stage company opportunities.
Pond Biofuels Inc. in Ontario, Canada has a functioning
pilot plant where algae is grown directly off of smokestack emissions from a
cement plant, and dried using waste heat. In May 2013, Pond Biofuels announced
a partnership with the National Research Council of Canada and Canadian Natural
Resources Limited to construct a demonstration-scale algal biorefinery at an
oil sands site near Bonnyville, Alberta.
Ocean Nutrition Canada in Halifax, Nova Scotia, Canada has
found a new strain of algae that appears capable of producing oil at a rate 60
times greater than other types of algae being used for the generation of biofuels.
VG Energy, a subsidiary of Viral Genetics Incorporated,
claims to have discovered a new method of increasing algal lipid production by
disrupting the metabolic pathways that would otherwise divert photosynthetic
energy towards carbohydrate production. Using these techniques, the company
states that lipid production could be increased several-fold, potentially
making algal biofuels cost-competitive with existing fossil fuels.
Algae production from the warm water discharge of a nuclear
power plant has been piloted by Patrick C. Kangas at Peach Bottom Atomic Power
Station, owned by Exelon Corporation. This process takes advantage of the
relatively high temperature water to sustain algae growth even during winter
months.
Companies such as Sapphire Energy and Bio Solar Cells are
using genetic engineering to make algae fuel production more efficient.
According to Klein Lankhorst of Bio Solar Cells, genetic engineering could
vastly improve algae fuel efficiency as algae can be modified to only build
short carbon chains instead of long chains of carbohydrates. Sapphire Energy
also uses chemically induced mutations to produce algae suitable for use as a
crop.
Some commercial interests into large-scale algal-cultivation
systems are looking to tie in to existing infrastructures, such as cement
factories, coal power plants, or sewage treatment facilities. This approach changes
wastes into resources to provide the raw materials, CO
2 and nutrients, for the system.
A feasibility study using marine microalgae in a
photobioreactor is being done by The International Research Consortium on
Continental Margins at the Jacobs University Bremen.
The Department of Environmental Science at Ateneo de Manila
University in the Philippines, is working on producing biofuel from a local
species of algae.
Genetic engineering
Genetic engineering the algae has been used to increase
lipid production or growth rates. Current research in genetic engineering
includes either the introduction or removal of enzymes. In 2007 Oswald et al.
introduced a monoterpene synthase from sweet basil into Saccharomyces
cerevisiae, a strain of yeast. This particular monoterpene synthase causes the
de novo synthesis of large amounts of geraniol, while also secreting it into
the medium. Geraniol is a primary component in rose oil, palmarosa oil, and
citronella oil as well as essential oils, making it a viable source of
triacylglycerides for biodiesel production.
The enzyme ADP-glucose pyrophosphorylase is vital in starch
production, but has no connection to lipid synthesis. Removal of this enzyme
resulted in the mutant, which showed
increased lipid content. After 18 hours of growth in nitrogen deficient medium
the sta6 mutants had on average 17 ng triacylglycerides/1000 cells, compared to
10 ng/1000 cells in WT cells. This increase in lipid production was attributed
to reallocation of intracellular resources, as the algae diverted energy from
starch production.
In 2013 researchers used a “knock-down” of fat-reducing
enzymes (multifunctional lipase/phospholipase/acyltransferase) to increase
lipids (oils) without compromising growth. The study also introduced an
efficient screening process. Antisense-expressing knockdown strains 1A6 and 1B1
contained 2.4- and 3.3-fold higher lipid content during exponential growth, and
4.1- and 3.2-fold higher lipid content after 40 h of silicon starvation.
Funding programs
Numerous Funding programs have been created with aims of
promoting the use of Renewable Energy. In Canada, the ecoAgriculture biofuels
capital initiative (ecoABC) provides $25 million per project to assist farmers
in constructing and expanding a renewable fuel production facility. The program
has $186 million set aside for these projects. The sustainable development
(SDTC) program has also applied $500 millions over 8 years to assist with the
construction of next-generation renewable fuels. In addition, over the last 2
years $10 million has been made available for renewable fuel research and
analysis
In Europe, the Seventh Framework Programme (FP7) is the main
instrument for funding research. Similarly, the NER 300 is an unofficial,
independent portal dedicated to renewable energy and grid integration projects.
Another program includes the horizon 2020 program which will start January 1,
and will bring together the framework program and other EC innovation and
research funding into a new integrated funding system
The American NBB's Feedstock Development program is
addressing production of algae on the horizon to expand available material for
biodiesel in a sustainable manner.
International policies
Canada
Numerous policies have been put in place since the 1975 oil
crisis in order to promote the use of Renewable Fuels in the United States,
Canada and Europe. In Canada, these included the implementation of excise taxes
exempting propane and natural gas which was extended to ethanol made from
biomass and methanol in 1992. The federal government also announced their
renewable fuels strategy in 2006 which proposed four components: increasing
availability of renewable fuels through regulation, supporting the expansion of
Canadian production of renewable fuels, assisting farmers to seize new
opportunities in this sector and accelerating the commercialization of new
technologies. These mandates were quickly followed by the Canadian provinces:
BC introduced a 5% ethanol and 5% renewable diesel
requirement which was effective by Jan 2010. It also introduced a low carbon
fuel requirement for 2012 to 2020.
Alberta introduced a 5% ethanol and 2% renewable diesel
requirement implemented April 2011. The province also introduced a minimum 25%
GHG emission reduction requirement for qualifying renewable fuels.
Saskatchewan implemented a 2% renewable diesel requirement
in 2009.
Additionally, in 2006, the Canadian Federal Government
announced its commitment to using its purchasing power to encourage the biofuel
industry. Section three of the 2006 alternative fuels act stated that when it
is economically feasible to do so-75% per cent of all federal bodies and crown
corporation will be motor vehicles.
The National Research Council of Canada has established
research on Algal Carbon Conversion as one of its flagship programs. As part of
this program, the NRC made an announcement in May 2013 that they are partnering
with Canadian Natural Resources Limited and Pond Biofuels to construct a
demonstration-scale algal biorefinery near Bonnyville, Alberta.
United States
Policies in the United States have included a decrease in
the subsidies provided by the federal and state governments to the oil industry
which have usually included $2.84 billion. This is more than what is actually
set aside for the biofuel industry. The measure was discussed at the G20 in
Pittsburgh where leaders agreed that “inefficient fossil fuel subsidies
encourage wasteful consumption, reduce our energy security, impede investment
in clean sources and undermine efforts to deal with the threat of climate
change". If this commitment is followed through and subsidies are removed,
a fairer market in which algae biofuels can compete will be created. In 2010,
the U.S. House of Representatives passed a legislation seeking to give
algae-based biofuels parity with cellulose biofuels in federal tax credit
programs. The algae based renewable fuel promotion act (HR 4168) was
implemented to give biofuel projects access to a $1.01 per gal production tax
credit and 50% bonus depreciation for biofuel plant property. The U.S
Government also introduced the domestic Fuel for Enhancing National Security
Act implemented in 2011. This policy constitutes an amendment to the Federal
property and administrative services act of 1949 and federal defense provisions
in order to extend to 15 the number of years that the Department of Defense
(DOD) multiyear contract may be entered into the case of the purchase of
advanced biofuel. Federal and DOD programs are usually limited to a 5 year
period
Other
The European Union (EU) has also responded by quadrupling
the credits for second-generation algae biofuels which was established as an
amendment to the Biofuels and Fuel Quality Directives
Companies
With algal biofuel being a relatively new alternative to
conventional petroleum products, it leaves numerous opportunities for drastic
advances in all aspects of the technology. Producing algae biofuel is not yet a
cost-effective replacement for gasoline, but alterations to current
methodologies can change this. The two most common targets for advancements are
the growth medium (open pond vs. photobioreactor) and methods to remove the
intracellular components of the algae. Below are companies that are currently
innovating algal biofuel technologies.
Algenol Biofuels
Founded in 2006, Algenol Biofuels is a global, industrial
biotechnology company that is commercializing its patented algae technology for
production of ethanol and other fuels. Based in Southwest Florida, Algenol’s
patented technology enables the production of the four most important fuels
(ethanol, gasoline, jet, and diesel fuel) using proprietary algae, sunlight,
carbon dioxide and saltwater for around $1.27 per gallon and at production
levels of 8,000 total gallons of liquid fuel per acre per year. Algenol's
technology produces high yields and relies on patented photobioreactors and
proprietary downstream techniques for low-cost fuel production using carbon
dioxide from industrial sources.Blue Marble Production
Blue Marble Production is a Seattle based company that is
dedicated to removing algae from algae-infested water. This in turn cleans up
the environment and allows this company to produce biofuel. Rather than just
focusing on the mass production of algae, this company focuses on what to do
with the byproducts. This company recycles almost 100% of its water via reverse
osmosis, saving about 26,000 gallons of water every month. This water is then
pumped back into their system. The gas produced as a byproduct of algae will
also be recycled by being placed into a photobioreactor system that holds
multiple strains of algae. Whatever gas remains is then made into pyrolysis oil
by thermochemical processes. Not only does this company seek to produce
biofuel, but it also wishes to use algae for a variety of other purposes such
as fertilizer, food flavoring, anti-inflammatory, and anti-cancer drugs.
Solazyme
Solazyme is one of a handful of companies which is supported
by oil companies such as Chevron. Additionally, this company is also backed by
Imperium Renewables, Blue Crest Capital Finance, and The Roda Group. Solazyme
has developed a way to use up to 80% percent of dry algae as oil. This process
requires the algae to grow in a dark fermentation vessel and be fed by carbon
substrates within their growth media. The effect is the production of
triglycerides that are almost identical to vegetable oil. Solazyme's production
method is said to produce more oil than those algae cultivated
photosynthetically or made to produce ethanol. Oil refineries can then take
this algal oil and turn it into biodiesel, renewable diesel or jet fuels.
Part of Solazyme's testing, in collaboration with Maersk
Line and the US Navy, placed 30 tons of Soladiesel(RD) algae fuel into the
98,000-tonne, 300-meter container ship Maersk Kalmar. This fuel was used at
blends from 7% to 100% in an auxiliary engine on a month-long trip from
Bremerhaven, Germany to Pipavav, India in Dec 2011. In Jul 2012, The US Navy
used 700,000 gallons of HRD76 biodiesel in three ships of the USS Nimitz
"Green Strike Group" during the 2012 RIMPAC exercise in Hawaii. The
Nimitz also used 200,000 gallons of HRJ5 jet biofuel. The 50/50 biofuel blends
were provided by Solazyme and Dynamic Fuels.
Sapphire Energy
Sapphire Energy is a leader in the algal biofuel industry
backed by the Wellcome Trust, Bill Gates' Cascade Investment, Monsanto, and
other large donors. After experimenting with production of various algae fuels
beginning in 2007, the company now focuses on producing what it calls
"green crude" from algae in open raceway ponds. After receiving more
than $100 million in federal funds in 2012, Sapphire built the first commercial
demonstration algae fuel facility in New Mexico and has continuously produced
biofuel since completion of the facility in that year. In 2013, Sapphire began
commercial sales of algal biofuel to Tesoro, making it one of the first
companies, along with Solazyme, to sell algae fuel on the market.
Diversified Technologies Inc.
Diversified Technologies Inc. has created a patent pending
pre-treatment option to reduce costs of oil extraction from algae. This
technology, called Pulsed Electric Field (PEF) technology, is a low cost, low
energy process that applies high voltage electric pulses to a slurry of algae.
The electric pulses enable the algal cell walls to be ruptured easily,
increasing the availability of all cell contents (Lipids, proteins and
carbohydrates), allowing the separation into specific components downstream.
This alternative method to intracellular extraction has shown the capability to
be both integrated in-line as well as scalable into high yield assemblies. The
Pulse Electric Field subjects the algae to short, intense bursts of
electromagnetic radiation in a treatment chamber, electroporating the cell
walls. The formation of holes in the cell wall allows the contents within to
flow into the surrounding solution for further separation. PEF technology only
requires 1-10 microsecond pulses, enabling a high-throughput approach to algal
extraction.
Preliminary calculations have shown that utilization of PEF
technology would only account for $0.10 per gallon of algae derived biofuel
produced. In comparison, conventional drying and solvent based extractions
account for $1.75 per gallon. This inconsistency between costs can be
attributed to the fact that algal drying generally accounts for 75% of the
extraction process. Although a relatively new technology, PEF has been
successfully used in both food decomtamination processes as well as waste water
treatments.
Origin Oils Inc.
Origin Oils Inc. has been researching a revolutionary method
called the Helix Bioreactor, altering the common closed-loop growth system.
This system utilizes low energy lights in a helical pattern, enabling each
algal cell to obtain the required amount of light. Sunlight can only penetrate
a few inches through algal cells, making light a limiting reagent in open-pond
algae farms. Each lighting element in the bioreactor is specially altered to
emit specific wavelengths of light, as a full spectrum of light is not
beneficial to algae growth. In fact, ultraviolet irradiation is actually
detrimental as it inhibits photosynthesis, photoreduction, and the 520 nm light-dark
absorbance change of algae.
This bioreactor also addresses another key issue in algal
cell growth; introducing CO2 and nutrients to the algae without disrupting or
over-aerating the algae. Origin Oils Inc. combats this issues through the
creation of their Quantum Fracturing technology. This process takes the CO2 and
other nutrients, fractures them at extremely high pressures and then deliver
the micron sized bubbles to the algae. This allows the nutrients to be
delivered at a much lower pressure, maintaining the integrity of the cells.
Proviron
Proviron has been working on a new type of reactor (using
flat plates) which reduces the cost of algae cultivation. At AlgaePARC similar
research is being conducted using 4 grow systems (1 open pond system and 3
types of closed systems). According to René Wijffels the current systems do not
yet allow algae fuel to be produced competitively. However using new (closed)
systems, and by scaling up the production it would be possible to reduce costs
by 10X, up to a price of 0,4 € per kg of algae.
Genifuels
Genifuel Corporation has licensed the high
temperature/pressure fuel extraction process and has been working with the team
at the lab since 2008. The company intends to team with some industrial partners
to create a pilot plant using this process to make biofuel in industrial
quantities. Genifuel process combines hydrothermal liquefaction with catalytic
hydrothermal gasification in reactor running at 350 Celsius (662 Fahrenheit)
and pressure of 3000 PSI.
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