2. 2
Introduction to Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-
chain alkyl (methyl, propyl or ethyl) esters. Biodiesel is typically made by chemically
reacting lipids (e.g., vegetable oil, anialcohol producing fatty acid esters.mal fat (tallow))
with an Biodiesel is meant to be used in standard diesel engines and is thus distinct from
the vegetable and waste oils used to fuel converted diesel engines. Biodiesel can be
used alone, or blended with petrodiesel. Biodiesel can also be used as a low carbon
alternative to heating oil. Its potential to reduce dependence on imported petroleum,
Its potential to help mitigate possible negative impacts of global climate change by
lowering net CO2 emissions from the transportation sector (though there is some
debate on this issue, and 3) tax incentives and publicity that have resulted from the
efforts of biodiesel advocates. Researchers at Sandia National Laboratories’ Combustion
Research Facility (CRF) have been studying biodiesel for a number of years to better
understand how and why biodiesel use could impact in-cylinder processes and, as a
result, the efficiency and emissions of advanced compression-ignition engines.
What is biodiesel?
Biodiesel is defined as “a fuel comprised of mono-alkyl esters of long chain fatty acids
derived from vegetable oils or animal fats”. Biodiesel is typically created by reacting
fatty acids with an alcohol in the presence of a catalyst to produce the desired mono-
alkyl esters and glycerin. After reaction, the glycerin, catalyst, and any remaining alcohol
or fatty acids are removed from the mixture. The alcohol used in the reaction is typically
methanol, although ethanol and higher alcohols also have been used. The majority of
the biodiesel currently produced in the U.S. is made from soybean oil, and soy biodiesel
typically consists of the five methyl esters shown in Fig. 1 [8]. While neat (i.e., 100%)
biodiesel can be used, a blend of between 2 and 20% (by volume) of biodiesel with
diesel fuel is recommended to avoid engine-compatibility problems. Biodiesel is not a
panacea, however. One notable disadvantage is that diesel-engine emissions of nitrogen
3. 3
oxides (NOx) tend to increase by approximately 1% for every 10 vol % of biodiesel that is
blended into diesel fuel. Biodiesel also can create problems in cold-weather conditions,
because certain of its constituent compounds can form crystals in the fuel. These
crystals can cause undesired effects like plugging of fuel filters so that fuel cannot travel
to the engine. In addition, biodiesel is often more susceptible to oxidative and biological
instabilities than conventional diesel fuel, though these issues generally can be avoided
by using the fuel promptly or by adding small amounts of stabilizer and biocide. Finally,
impurities such as unreacted fatty acids or alcohol, as well as glycerin or catalyst left
over from the production process, can lead to accelerated wear or corrosion of engine
components. Proper quality control is critical for avoiding unnecessary problems during
the introduction of biodiesel into widespread use.
Past and current biodiesel research at the CRF
Early biodiesel research at the CRF showed that the elevated latent and specific
heats of biodiesel compounds can lead to longer liquid penetration lengths within the
combustion chamber than would be measured for diesel fuel injected into the same
conditions;. This could cause impingement and adhesion of liquid fuel on in-cylinder
surfaces, which could lead to increased fuel consumption and emissions, as well as oil
degradation. A later study investigating molecular-structure effects on the soot-reduction
characteristics of different oxygenated fuel compounds found that an ether structure was
more effective than an ester structure (like that found in biodiesel) at attenuating in-
cylinder soot concentrations in experiments. Subsequent reaction-path analysis provided
an explanation by showing that more than 30% of the oxygen in the ester structure was
unavailable for the prevention of soot-precursor formation. Current biodiesel research in
the CRF’s Advanced Fuels Optical Engine Laboratory is focused on determining the
underlying reason(s) behind the observed increased NOx emissions with biodiesel
fueling. Hypotheses in the literature to explain the elevated biodiesel NOx emissions
include: increased bulk modulus of biodiesel causing an advanced start of combustion,
larger premixed-burn fraction, and increased stoichiometric adiabatic flame temperature.
Recently, a study was conducted wherein a hydrocarbon (i.e., non-oxygenated) reference
fuel was formulated to have the same ignition delay as neat biodiesel at a given operating
condition. Figure 3 shows that, even when start of combustion and premixed-burn
fraction were matched between the two fuels, NOx emissions were still found to be ~10%
4. 4
higher for the neat biodiesel fuel. Furthermore, computed stoichiometric adiabatic flame
temperatures were found to be identical for the reference fuel and a number of other
oxygenated and non-oxygenated fuel components, including a biodiesel surrogate
(methyl oleate). These results show that the three hypotheses above cannot fully explain
the increased NOx emissions with biodiesel fueling. Experiments to identify the primary
source(s) of increased biodiesel NOx emissions are currently underway.
Figure 1. Molecular structures of the five methyl esters that typically comprise soy
biodiesel.
Figure 2
Superimposed images of Mie scattering from the fuel-jet core showing the liquid-
penetration length, and schlieren images showing the jet spreading angle. Image pairs
are shown for neat biodiesel and conventional #2 diesel fuel. The liquid-penetration
5. 5
length is more than 30% longer for neat biodiesel than for #2 diesel fuel at this
condition, which could lead to impingement of liquid fuel on in-cylinder surfaces. The
ambient temperature and density into which the fuel is injected are 1000 K and
14.8 kg/m3
, respectively.
Measured NOx emissions are ~10% higher on average when fueling with neat biodiesel
relative to fueling with a hydrocarbon reference fuel, even when the start of
combustion and premixed-burn fraction are matched between fuels (inset) [14]. The
engine speed (800 rpm) and intake conditions also were the same for both fuels at each
load point.
Biodiesel Works
If you've read or watched the news lately, you've probably come across some article,
snippet or sound bite related to oil and oil prices. Even in your daily routines, there's a
good chance of someone mentioning it. Whether it's in automotives, economics, history,
geography or politics, oil has managed to filter into almost every aspect of our daily lives.
It's one of the most discussed (and controversial) commodities that consumers rely on
6. 6
daily.All of this talk about oil sparks continued interest in gasoline alternatives. Things
like electric cars and hydrogen fuel cells are being talked about as feasible alternatives to
oil. As technology improves, these concepts could become reality. But what about
now?Lost in the mix are the biofuels, fuels made from biological ingredients instead of
fossil fuels. These starting ingredients can range from corn to soybeans to animal fat,
depending on the type of fuel being made and the production method.In this article, we'll
take a closer look at biodiesel, one of the major biofuels. For starters, it would be a good
idea to check out How Car Engines Work and How Diesel Engines Work to get some
background. After that, head back over and we'll separate biodiesel fact from
fiction.Generally speaking, biodiesel is an alternative or additive to standard diesel fuel
that is made from biological ingredients instead of petroleum (or crude oil). Biodiesel is
usually made from plant oils or animal fat through a series of chemical reactions. It is
both non-toxic and renewable. Because biodiesel essentially comes from plants and
animals, the sources can be replenished through farming and recycling.Biodiesel is safe
and can be used in diesel engines with little or no modification needed. Although
biodiesel can be used in its pure form, it is usually blended with standard diesel fuel.
Blends are indicated by the abbreviation Bxx, where xx is the percentage of biodiesel in
the mixture. For example, the most common blend is B20, or 20 percent biodiesel to 80
percent standard. So, B100 refers to pure biodiesel.
vegetable oils or animal fats, designated B100, and meeting the requirements of Biofuels,
such as ethanol made from corn and biodiesel made from soybeans, help support
American agriculture. Biodiesel isn't just a catch-all term, however. There is also a
formal, technical definition that is recognized by ASTM International (known formerly as
the American Society for Testing and Materials), the organization responsible for
providing industry standards. According to the National Biodiesel Board (NBB), the
technical definition of biodiesel is as follows: a fuel comprised of mono-alkyl esters of
long chain fatty acids derived from ASTM D 6751. That sounds kind of rough, but it's a
7. 7
lot more familiar than you may think -- you encounter these fatty acids every day. We'll
look at them in more detail in the next section.
How Biodiesel Works
Part of what makes biodiesel so appealing and interesting is that it can be made from
numerous natural sources. Although animal fat can be used, plant oil is the largest
source of biodiesel. You've probably used some of these in the kitchen. Scientists and
engineers can use oils from familiar crops such as soybean, rapeseed, canola, palm,
cottonseed, sunflower and peanut to produce biodiesel. Biodiesel can even be made
from recycled cooking grease! The common thread shared by all biodiesel sources is
that they all contain fat in some form. Oils are just fats that are liquid at room
temperature. These fats, or triacylglycerols (sometimes called triglycerides) are made up
of carbon, hydrogen, and oxygen atoms bound together and arranged into a specific
pattern. These triacylglycerols are pretty prevalent. In addition to household vegetable
oils, they're also in common things like butter and lard. You may have seen a triglyceride
count listed if you've been to a doctor and had some blood work done. One way to
visualize these triacylglycerols is to think of a capital "E." Forming the vertical backbone
of this E is a molecule known as glycerol. Glycerol is a common ingredient used in
making such things as soap, pharmaceuticals and cosmetics. Attached to this glycerol
backbone and forming the horizontal elements of the E are three long chains composed
of carbon, hydrogen, and oxygen. These are called fatty acids. So how do these
triacylglycerols end up in a car, truck or boat? Biodiesel is not pure vegetable oil.
Although raw vegetable oil has been used to fuel diesel engines in the past, it has
usually caused problems. The raw fat or oil must first undergo a series of chemical
reactions in order to become fuel. There are a few different ways to make biodiesel, but
8. 8
most manufacturing facilities produce industrial biodiesel through a process called
transesterification. In this process, the fat or oil is first purified and then reacted with an
alcohol, usually methanol (CH3OH) or ethanol (CH3CH2OH) in the presence of a catalyst
such as potassium hydroxide (KOH) or sodium hydroxide (NaOH). When this happens,
the triacylglycerol is transformed to form esters and glycerol. The esters that remain are
what we then call biodiesel. Is this old news? In the next section, we'll examine some of
the history and motivation behind the biofuels movement.
H H H H H
/ | /
C-----------C-----------C
| | |
O O O
C=O C=O C=O
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H-C-H H-C-H H-C-H
| | |
H H H
9. 9
Types of Biodiesel
There are different types of biodiesel. Although there are set standards that has to be met
before a fuel can be classified as biodiesel, there are some room for differences.The
Feedstock that is used to make the biodiesel with will determine these differences as
biodiesel tend to take on the properties of the feedstock. For Example, soybean biodiesel
will differ slightly from biodiesel made from Jatropha or palm oil, even though all three
types can still officially be classified as Biodiesel.The Differences usually lay in their
emissions when burned. Jatropha biodiesel will for example emit less Carbon dioxide
than Linseed Biodiesel but more than Soybean biodiesel.All the different types of
biodiesel will still emit less Co2 and other harmful gasses then conventional petroleum
diesel.Just like petroleum diesel manufacturers try to differentiate their product from
those of their competitors by adding additives and giving it different names so too
biodiesel manufacturers try to separate themselves and make their product look better
than the product of their competition.Different biodiesel blends will also differ from each
other and from pure biodiesel. B5 will differ in performance and emissions from
B20.When choosing which type of biodiesel to use always try to choose the type that is
most environmentally friendly and that suits your circumstances. When choosing the
most environmentally friendly fuel don't only look at the emissions, also look at where it
came from. Try using Biodiesel made from Waste vegetable oil(WVO) because it uses
something that would normally go to waste. Try using Jatropha Biodiesel because it is
not in competition with other food crops.If you stay somewhere that experience very cold
winters try using biodiesel made from Rapeseed oil or biodiesel with additives added to
stop it from gelling. If you are more concerned about emmissions try using Soybean
Biodiesel rather than biodiesel made from linseed oil as this haslower Co2 and Nox
Emissions.
One of the major selling points of biodiesel is that it is environmentally friendly.
Biodiesel has fewer emissions than standard diesel, is biodegradable, and is a
renewable source of energy. Emissions control is central to the biodiesel argument,
especially in legislation matters. There are a few components of emissions that are
especially harmful and cause concern among scientists, lawmakers, and consumers.
10. 10
Sulfur and its related compounds contribute to the formation of acid rain; carbon
monoxide is a widely recognized toxin; and carbon dioxide contributes to the greenhouse
effect. There are also some lesser known compounds that cause concern, such as
polycyclic aromatic hydrocarbons (PAHs), ring-shaped compounds that have been linked
to the formation of certain types of cancer. Particulate matter (PM) has negative health
effects, and unburned hydrocarbons contribute to the formation of smog and
ozone.Biodiesel does reduce hazardous emissions. Of the current biofuels, biodiesel is the
only one to have successfully completed emissions testing in accordance with the Clean
Air Act.
Average Biodiesel Emissions Compared to Conventional Diesel
Emission Component B100 B20
Total Unburned Hydrocarbons -67% -20%
Carbon Monoxide -48% -12%
Particulate Matter -47% -12%
NOx +10% +2%
Sulfates -100% -20%
PAH -80% -13%
Source: National Biodiesel Board
In addition, B100 can reduce CO2 emissions by 78 percent and lower the carcinogenic
properties of diesel fuel by 94 percent (National Biodiesel Board, U.S. DOE Office of
Transportation Technologies).Another feature of biodiesel is that it is biodegradable,
meaning that it can decompose as the result of natural agents such as bacteria. According
to the EPA, biodiesel degrades at a rate four times faster than conventional diesel fuel.
This way, in the event of a spill, the cleanup would be easier and the aftermath would not
be as frightening. This would also hold true for biodiesel blends.Biodiesel could also
lower U.S. dependence on imported oil and increase our energy security. Most biodiesel
in the U.S. is made from soybean oil, which is a major domestic crop. With U.S.
petroleum demands increasing and world supply decreasing, a renewable fuel such as
biodiesel, if properly implemented, could alleviate some of the U.S. energy
demands.Biodiesel also contributes to an engine's lubricity, or its ease of movement.
Biodiesel acts as a solvent, which helps to loosen deposits and other gunk from the
11. 11
insides of an engine that could potentially cause clogs. Since pure biodiesel leaves no
deposits of its own, this results in increased engine life. It is estimated that a biodiesel
blend of just 1 percent could increase fuel lubricity by as much as 65 percent (U.S. DOE
Office of Transportation Technology).Biodiesel is also safer. It is non-toxic (about 10
times less toxic than table salt) and has a higher flashpoint than conventional diesel.
Because it burns at a higher temperature, it is less likely to accidentally combust. This
makes movement and storage regulations easier to accommodate. Next, we'll look at the
cons and the future of biodiesel.
Photo courtesy Paul RoesslerMicroalgae, organisms from which a diesel-like fuel can be
derived: Cultured in the American southwestern deserts, NREL-developed microalgae
may one day produce large amounts of lipids for conversion to biodiesel fuel.
Biodiesel Fuel Uses
Our Ultimate Biodiesel Guide is designed to educate the public on the reasons why they
should switch from fossil fuel energy to a greener source. This comprehensive resource
also explains the production of biodiesel in an easy follow, simple to understand way. In
addition to our manual, we are also offering over 200 pages of bonus material to further
12. 12
assist our readers.There already many biodiesel fuel uses, and as technology continues
to develop, so do the opportunities to replace traditional fossil fuels with this viable
alternative. Unfortunately, as the technology grows so does the library of information.
Many people simply find the chore of wading through data and tests to be
overwhelming. The first of our three bonus reports eliminates this problem by
presenting the information in a complete and concise fashion.“Fuelling Direct Injected
Diesel Engines With Biodiesel” is a report that summarizes the plethora of data
regarding biodiesel fuel uses. This publication educates readers on the results of reports
that have studied the effects of using this alternative fuel in engines. It also
amalgamates research and provides clear conclusions to help eliminate false
information. It is unfortunate, but as with any alternative technology, biodiesel fuel is
plagued by myths and falsehoods that we are actively trying to eliminate.In addition to
our bonus material, we also offer readers a periodic newsletter publication. This
newsletter, titled “Alternative Energy,” is the first of its kind to provide sound advice
and breaking news about alternative fuels. Some recent information that we have
shared includes uses for biodiesel production by products, what going biodiesel can
mean for a warranty, and ways to get free raw materials worldwide.Speaking of uses for
biodiesel production by products, this is just one example of how our Ultimate Biodiesel
Guide walks readers through the entirety of the process from inception to completion.
We are not simply here to help people produce the energy, we want to ensure that they
find the products they need to establish a safe production procedure.
Environmental impact of biodiesel
Greenhouse gas emissions
An often mentioned incentive for using biodiesel is its capacity to lower greenhouse gas
emissions compared to those of fossil fuels. If this is true or not depends on many factors.
Especially the effects from land use change have potential to cause even more emissions
than what would be caused by using fossil fuels alone.[3]
Carbon dioxide is one of the major greenhouse gases. Although the burning of biodiesel
produces carbon dioxide emissions similar to those from ordinary fossil fuels, the plant
13. 13
feedstock used in the production absorbs carbon dioxide from the atmosphere when it
grows. Plants absorb carbon dioxide through a process known as photosynthesis which
allows it to store energy from sunlight in the form of sugars and starches. After the
biomass is converted into biodiesel and burnt as fuel the energy and carbon is released
again. Some of that energy can be used to power an engine while the carbon dioxide is
released back into the atmosphere.When considering the total amount of greenhouse gas
emissions it is therefore important to consider the whole production process and what
indirect effects such production might cause. The effect on carbon dioxide emissions is
highly dependent on production methods and the type of feedstock used. Emissions from
growing the feedstock (e.g. Petrochemicals used in fertilizers)Emissions from
transporting the feedstock to the factoryEmissions from processing the feedstock into
biodiesel
Other factors can be very significant but are sometimes not considered. These include:
Emissions from the change in land use of the area where the fuel feedstock is
grown.Emissions from transportation of the biodiesel from the factory to its point
of useThe efficiency of the biodiesel compared with standard dieselThe amount of
Carbon Dioxide produced at the tail pipe. (Biodiesel can produce 4.7% more)The
benefits due to the production of useful by-products, such as cattle feed or
glycerine
Environmental Impacts of Biofuels
One of the major reasons for producing biofuels is to reduce greenhouse gas emissions
and to mitigate the effects of global warming produced by fossil fuels.
However, according to the Food and Agriculture Organisation of the UN, some
unintended impacts of biofuel production are on land, water and biodiversity. They are
affected by agricultural production and if the agricultural production is intensified then
the side effects are even greater.The common conception is that growing crops for
biofuels will offset the greenhouse gas emissions because they However, the FAO in its
The State of Food and Agriculture 2008 report, says that scientific studies have shown
that different feedstocks grown for biofuels have different environmental
effects."Depending on the methods used to produce the feedstock and process the fuel,
some crops can even generate more greenhouse
It warns that nitrous oxide that is released from fertilisers that might be put on the ground
14. 14
to help the crops grow will have 300 times more global warming effect
thancarbondioxide.
It says that greenhouse gases can be emitted by both direct and indirect land use changes
because of increased biofuels production by the conversion of land use There is also a
difference in the greenhouse gas savings of different crops as maize produced for ethanol
has an annual greenhouse gas saving of about 1.8 tonnes per hectare according to the
report, but switchgrass, which is a second generation crop has a saving of 8.6 tonnes. The
FAO says that the amount of emissions produced throughout the production cycle also
have to be taken into account and there is a balance to be drawn between the direct
greenhouse gas savings, the emissions and the potentially valuable by-products produced
in biofuel production.
The balance also has to be drawn between the greenhouse gas emissions produced in the
production and burning of biofuels and the production and burning of fossil fuels.These
balances can vary between different feedstocks and different locations and production
methods.
"Most studies have found that producing first-generation biofuels from current
feedstocks results in emission reductions in the range of 20-60 per cent relative to fossil
fuels, provided the most efficient systems are used and carbon releases deriving from
land-use change are excluded," the report says.However, it adds that Brazil has the best
conversion rate and the highest savings with typical reductions of between 70 and 90
per cent.One of the most telling impacts of biofuels is any change in land use that might
15. 15
take place.The FAO says the impact is at the beginning of the production cycle and any
change in land use might take years to balance out the effects and in some cases could
show fossil fuels to be more efficient than the biofuels. This would be particularly
relevant is rainforest, peatlands, savannahs or grasslands are used to grow feedstocks to
produce ethanol or biodiesel.Some studies have shown that in some cases more carbon
would be sequestered by converting a cropland used for a biofuel feedstock to forest
than the production of the fuel itself."If the objective of biofuel support policies is to
mitigate global warming, then fuel efficiency and forest conservation and restoration
would be more effective alternatives," the report says.The FAO says that energy
efficiency and conservation are just as important and can be more cost effective than
production of biofuels."A comprehensive understanding of the relevant issues, including
land-use change, and proper assessment of greenhouse gas balances are essential in
order to ensure that bioenergy crops have a positive and sustainable impact on climate-
protection efforts.
Scale models
If this approach works, it will not only be beneficial in its own right—modestly reducing
greenhouse-gas emissions while making money for its investors—it will also provide a
lasting market incentive to scientists to devise better ways of turning cellulose into sugar.
This gives the prospects for this generation of biofuels a plausibility that was missing
from its predecessors. The drop-in firms are starting to come out of the laboratory, float
themselves on the stockmarket, team up with oil companies and build their first factories.
The dice, in other words, are rolling.
The project is part of a joint venture by Shell and Cosan; with a capacity of more than 2
billion litres a year, it is the world’s largest biofuel operation, and it owns a 16.4% stake
in Codexis. At the moment, the joint venture’s business is based on fermenting cane
sugar into ethanol, but the new plant would start changing that. Codexis’s enzymes and
bacteria can turn sugar into molecules called straight-chain alkanes which have between
12 and 16 carbon atoms in them. Such alkanes are the main ingredients of diesel fuel.
In April Codexis became the first start-up involved in drop-in fuels to float itself on a
stockmarket—which in this case was NASDAQ, America’s main market for high-tech
stocks. But it is not the last. Another firm that recently completed its NASDAQ flotation
16. 16
is Amyris, of Emeryville, which is also in the San Francisco Bay area. Amyris started off
using large-scale genetic engineering, also known as synthetic biology, to create bugs that
make a malaria drug. But now it, too, has a product that it claims is a drop-in biodiesel.
And it, too, has hooked up with an oil company: Total, of France, which owns 17% of the
firm.
High-fibre diet
The success of all this obviously depends on the price of sugar, which is rising.
Historically, the cost of making Brazilian ethanol has been about 26 cents a litre. Diesel
will cost more, but petroleum-based diesel sells in America for 57 cents a litre before
distribution costs and tax, so there should be room for profit. Nevertheless, if drop-in
fuels are to become a truly big business they need a wider range of feedstocks.
Until recently, the assumption has been that cellulose would take over from sugar and
starch as the feedstock for making biofuels. Making cellulose into sugar is technically
possible, and many firms are working on that possibility. Some are using enzymes. Some
are using micro-organisms. Still others have a hybrid approach, part biotechnological and
part traditional chemistry. And some go for pure chemistry, breaking the cellulose down
into a gaseous mixture of hydrogen and carbon monoxide before building it back up into
something more useful.
The reason for this enthusiasm has been government mandates: America’s Renewable
Fuel Standard (RFS-2) and its European equivalent. On pain of fines, but with the carrot
of subsidies, these require that a certain amount of renewable fuel be blended into
petroleum-based fuels over the next decade or so. RFs-2 calls for a 10% blend of
cellulosic fuel by 2022.
The targets in RFS-2, though, represent a huge climbdown. Its predecessor, RFS-1, called
for 379m litres of cellulosic ethanol to be produced in 2010; RFS-2 mandates only 25m
litres. The industry in fact has a capacity of about 70m litres today, according to the
Biotechnology Industry Organisation (BIO), an American lobby group.
The reduced expectations reflect the fact that making fuel out of cellulose turns out to be
hard and costly. Today’s cellulosic ethanol is competitive with the petrol it is supposed to
displace only when the price of crude oil reaches $120 a barrel. In Dr Shaw’s view, a lot
17. 17
can be done by scaling up (and using the appropriate enzymes, of course, which Codexis
will be only too happy to sell you). And big plants will, indeed, bring the price down—
probably not to the point where cellulosic ethanol can compete in a fair fight, but quite
possibly to a level at which fuel companies will make or buy the stuff rather than pay
fines for not doing so.
Phil New, the head of biofuels at BP, says his firm is determined to comply with RFS-2.
To that end it is planning a plant in Florida that will have a capacity of 137m litres when
it comes on stream in 2013. It is one of seven cellulosic-ethanol fermentation plants with
annual capacities above 38m litres (that is, 10m gallons) which BIO says should be
running by 2013, with a further seven making ethanol using syngas conversion. However,
such claims are not that different from those made three years ago—which singularly
failed to bear fruit.
Grassed up
If things work out better this time, it still leaves the question of where the cellulose is to
come from. The answer is likely, in one form or another, to be grass.
Though they look very different, sugar cane and corn are both grasses. So is wheat, which
is corn’s counterpart as the starch source of choice in the EU. A simple way of garnering
cellulose is to gather up the leftovers when these crops have been processed—bagasse
from sugar cane, stover from corn and straw from wheat.
That is a start, but it will not be enough, Wood is a possibility, particularly if it is dealt
with chemically, rather than biologically (much of the carbon in wood is in the form of
lignin, a molecule that is even tougher than cellulose). But energy-rich grasses look like
the best bet. Ceres, which is based in Thousand Oaks, California, has taken several
species of fast-growing grass, notably switchgrass and sorghum, and supercharged them
to grow even faster and put on more weight by using a mixture of selective breeding and
genetic engineering. Part of America’s prairies, the firm hopes, will revert to grassland
and provide the cellulose that biofuels will need. The Energy Biosciences Institute that
BP is funding at the University of Illinois, in Urbana-Champaign, is working on hybrid
miscanthus, an ornamental grass that can produce truly remarkable yields.
Drop in or drop out
18. 18
Such a future, though, depends on cars continuing to be powered by liquid fuels. A large
shift to electric cars would put the kibosh on the biofuel market as currently conceived by
most of its supporters; but it would not necessarily kill the principle of using plants to
convert sunlight into car-power. The goal of reducing emissions needs low-carbon
generators to power the grid the electric cars draw juice from. Put the energy crops in
generators instead of distilleries and off you go.
Richard Hamilton, the boss of Ceres, says he is indifferent as to whether his grasses end
up in petrol tanks or power stations. Others think making them into electricity might be a
better answer anyway. A study published last year by Elliott Campbell, of the University
of California, Merced, and his colleagues suggested that turning crops into electricity, not
fuel, would propel America’s cars 80% farther and reduce greenhouse-gas emissions
even more. Electrons are easy to transport and burning uses all of the fuel value of a
plant—including that stored in the lignin which current processing methods find hard to
deal with.
The electrification of cars, however the electricity might be generated, would be the end
of the road for ethanol. But not necessarily for drop-ins. There is no realistic prospect for
widespread electric air travel: the jet engines on aircraft need the high-energy density that
only chemical fuels can provide. So if you want low-carbon flying, drop-in biofuels are
the only game in town. And civil aviation alone is expected to use 250 billion litres of
19. 19
fuel this year, is growing fast and could pay a premium if its emissions were subject to a
cap or a tax. Over the long run, the future for biofuels may be looking up.
Biodiesel advantages and disadvantages
Biodiesel is form of diesel fuel that is less harmful to environment compared to standard
diesel. Biodiesel, just like any other fuel has its advantages as well as disadvantages, and
through this article I'll try to mention the most important ones. Let's start with
advantages.
Biodiesel advantages:
Biodiesel isn't toxic.
Biodiesel is biodegradable.
Biodiesel is safer to handle compared to standard diesel.
Biodiesel can be easily blended with standard diesel, and it can be used in most of today's
vehicles even in form of pure biodiesel B100.
Biodiesel can help cut our reliance on fossil fuels, and improve our energy security and
energy independence.
Biodiesel could be massively produced in many parts of the world, the US alone has the
capacity to produce annualy more than 50 million gallons of biodiesel.
Production and use of biodiesel accounts for significantly less emissions compared to
standard diesel, approximately 78% less emissions compared to standard diesel.
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Biodiesel has very good lubricating properties, significantly better than standard diesel
which can prolong engine's life.
Biodiesel has shorter ignition delay compared to standard diesel.
Biodiesel has no sulfur content, and so it doesn't contribute to acid rain formation.
Biodiesel disadvantages:
Biodiesel is currently mostly produced from corn which could lead to food shortages and
increased food prices. The end result of this could be more hunger in the world.
Biodiesel is 20 times more suspectible to water contamination compared to standard
diesel, and this could lead to corrosion, rotten filters, pitting in the pistons, etc.
Pure biodiesel has significant problems with low temperatures.
Biodiesel is significantly more expensive compared to standard diesel.
Biodiesel has significantly less energy content compared to standard diesel, around 11%
less compared to standard petroleum diesel.
Biodiesel can release nitrogen oxide which can lead to the formation of smog.
Biodiesel, despite emitting significantly less harmful carbon emission compared to
standard diesel, still somehwat contributes to global warming and climate change.
Refrences
1. ^ "Biodiesel 101 - Biodiesel Definitions" (?). National Biodiesel Board.
http://www.biodiesel.org/resources/definitions/default.shtm. Retrieved 2008-02-
16.
2. ^ "Biodiesel Basics". National Biodiesel Board.
http://www.biodiesel.org/resources/biodiesel_basics/. Retrieved 2009-01-30.
21. 21
3. ^ "Biodiesel Handling and Use Guide, Forth Edition". National Renewable Energy
Laboratory. http://www.nrel.gov/vehiclesandfuels/pdfs/43672.pdf. Retrieved
2011-02-13.
4. ^ "American Society for Testing and Materials". ASTM International.
http://www.astm.org. Retrieved 2011-02-13.
5. ^ "43672.pdf". nrel.gov. 2009 [last update].
http://www.nrel.gov/vehiclesandfuels/pdfs/43672.pdf. Retrieved December 21,
2011.
6. ^ McCormick, R.L.. "2006 Biodiesel Handling and Use Guide Third Edition" (PDF).
http://www.nrel.gov/vehiclesandfuels/npbf/pdfs/40555.pdf. Retrieved 2006-12-
18.
7. ^ "US EPA Biodiesel Factsheet".
http://www.epa.gov/smartway/growandgo/documents/factsheet-
biodiesel.htm.[dead link]
8. ^ "Twenty In Ten: Strengthening America's Energy Security". Whitehouse.gov.
http://georgewbush-
whitehouse.archives.gov/stateoftheunion/2007/initiatives/energy.html.
![2
Introduction to Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-
chain alkyl (methyl, propyl or ethyl) esters. Biodiesel is typically made by chemically
reacting lipids (e.g., vegetable oil, anialcohol producing fatty acid esters.mal fat (tallow))
with an Biodiesel is meant to be used in standard diesel engines and is thus distinct from
the vegetable and waste oils used to fuel converted diesel engines. Biodiesel can be
used alone, or blended with petrodiesel. Biodiesel can also be used as a low carbon
alternative to heating oil. Its potential to reduce dependence on imported petroleum,
Its potential to help mitigate possible negative impacts of global climate change by
lowering net CO2 emissions from the transportation sector (though there is some
debate on this issue, and 3) tax incentives and publicity that have resulted from the
efforts of biodiesel advocates. Researchers at Sandia National Laboratories’ Combustion
Research Facility (CRF) have been studying biodiesel for a number of years to better
understand how and why biodiesel use could impact in-cylinder processes and, as a
result, the efficiency and emissions of advanced compression-ignition engines.
What is biodiesel?
Biodiesel is defined as “a fuel comprised of mono-alkyl esters of long chain fatty acids
derived from vegetable oils or animal fats”. Biodiesel is typically created by reacting
fatty acids with an alcohol in the presence of a catalyst to produce the desired mono-
alkyl esters and glycerin. After reaction, the glycerin, catalyst, and any remaining alcohol
or fatty acids are removed from the mixture. The alcohol used in the reaction is typically
methanol, although ethanol and higher alcohols also have been used. The majority of
the biodiesel currently produced in the U.S. is made from soybean oil, and soy biodiesel
typically consists of the five methyl esters shown in Fig. 1 [8]. While neat (i.e., 100%)
biodiesel can be used, a blend of between 2 and 20% (by volume) of biodiesel with
diesel fuel is recommended to avoid engine-compatibility problems. Biodiesel is not a
panacea, however. One notable disadvantage is that diesel-engine emissions of nitrogen](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)