Biodiesel is a type of fuel that is made from the lipids of animals and plants. Because biodiesel has the potential to come from regrow-able plant sources, it is becoming one of the most auspicious forms of alternative fuel in the world. The name biodiesel is deceiving however. One might think the diesel in biodiesel comes from its chemical composition, but the composition of biodiesel is generally:
And the chemical composition of common diesels is:
Biodiesel is classified as a diesel because both biodiesel and diesel undergo the same internal combustion process to turn into energy. Internal combustion is the act of converting chemical energy into mechanical energy and when discussing vehicles, this can be done in two ways: gasoline engines and diesel engines.
A gasoline engine allows fuel to mix in with air from the outside in a small chamber. This mixture is then pushed into a small volume of the chamber and ignited by a spark that creates the combustion. A diesel engine, on the other hand, compresses and heats the air first in the same chamber. The fuel is then injected into the chamber and because the air is already heated up, the fuel ignites.1 Both ignitions processes can be seen in Figure C below.
So how is biodiesel generally used? To those bold enough, pure 100% biodiesel can be used in vehicles, but most vehicles approve of B2 (2% biodiesel), B5 (5% biodiesel) and B20 (20% biodiesel).2 This is primarily because despite being renewable, biodiesel has disadvantages as an organic product.
Advantages and Disadvantages of Biodiesel
Although it has much promise, biodiesel has some disadvantages to other fuel sources. However, many of these have been accommodated for. The first disadvantage is in its energy content. A study by the US Department of Energy’s Energy Efficiency and Renewable Energy Department compared the energy content of 100% petroleum diesel to 100% biodiesel in 2003. When these two fuels were compared, it was found that the energy content of the biodiesel was actually 10% less than the energy content in petroleum diesel. Soon after, B20 biodiesel (80% petroleum diesel) was compared with 100% petroleum diesel and the energy content was found to be 2% less in the B20 mixture.2
Another disadvantage is its behavior as a solvent. This can be a problem particularly with older diesel engines that use biodiesel. At low temperatures, biodiesel is prone to crystallization that can prevent the fuel from being efficient. In Hannu Jääskeläinen’s experiment, Low Temperature Operability of Biodiesel, he noticed the formation of saturated monoglycerides, sterol glucosides, soaps and even water particles in the engine after reducing the temperature of the car.3
To engineer around its behavior, several tests have been done that have helped established a critereon for optimal biodiesel. This optimal formula is known as the Biodiesel Standard, which is a specification set by a country to ensure that biodiesel doesn’t radically damage a car. Figure D shows some countries and the biodiesel standards that apply to each particular country.
Part of the Biodiesel Standard includes a series a tests: a cloud point test, a low temperature flow test (LTFT) and a cold filter plugging point (CFPP). These tests are used to observe and particle formation that occurs at low temperatures.4 And as a even more preventive measure, a new test was conceived in 2005, called the cold soak filtration test (CSFT) after it was observed that precipitates were forming even above the cloud point (a temperature that divides solubility and insolubility). In this test, biodiesel is chilled and then warmed back up to room temperature after 16 hours. 300 milliliters must flow through a filter in under 360 seconds for the biodiesel to be used under the US Biodiesel Specification Guideline ASTM D6751.5 A video of the CSFT performed at the National Biodiesel Conference can be seen in Figure E.
The hugest problem with biodiesel is its availability. With an energy content of 90% of harmful sulfuric petrodiesel and preventive measures of its crystallization at low temperatures, biodiesel has been scientifically powerful and improved. Biodiesel lacks, however, in its awareness and its amount. The National Biodiesel Board found that all 50 states have the capability to produce biodiesel, but there are only 19 pumps in the country that produce biodiesel.6
It’s alarming in that so many problems have been engineered around and so many of its advantages are present to have biodiesel go unnoticed. And its advantages will surely outweigh its disadvantages in the 21st century. Not only would biodiesel decrease our dependency on foreign fossil fuels, but it is non-toxic and biodegradable. It is also safer in the regard that it is less flammable with a flash point of 212 degrees Fahrenheit rather than a flashpoint between 126 and 204 degrees Fahrenheit in petroleum diesel.7
But above all else, biodiesel is carbon neutral. At an age with drastically rising carbon levels, creating a viable carbon neutral cycle is as good of a solution as any. What carbon neutrality essentially means is that the amount of carbon absorbed in the plants is the amount of carbon burned in the combustion of biodiesel. This process can be seen in Figure F. In terms of emissions, exhausting biodiesel over petroleum diesel would also eliminate levels of sulfur in our atmosphere or even other particulate matter due to its organic nature. Scientists are still doing research into biodiesel’s other products in emissions (such as nitrogen oxides)7, but the carbon neutral cycle remains to be the clearest incentive for biodiesel production.
Transesterification: The Reaction to Biodiesel
“The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become, in the course of time, as important as the petroleum and coal tar products of the present time.”
Rudolf Diesel, 1912
Contrary to popular belief, the first product of biodiesel was accidentally conceived in the 1800’s and the first time it was used in a diesel engine was by Rudolph Diesel on August 10th, 1893. Fun Fact: This day is known as Biodiesel Day. Before then, E. Duffy and J. Patrick had used the same reaction that created biodiesel to create soap, another product of the reaction in 1853.8 The reaction that makes both these products is called Transesterification. Transesterification is when an ester combines with an alcohol to create a new ester and an alcohol.9 In biodiesel production, the incoming esters are the free fatty acids of a plant organism. The free fatty acids mix with alcohol to produce methyl ester biodiesel and glycerol.
The most common alcohols used in this procedure are methanol and ethanol to create a chemical structure that is as similar as possible to other fuels. To use a different alcohol would create fuel properties that would prevent the fuel from being as effective in a diesel engine.10 Scientists refer to the forward reaction as polyester production and the reverse reaction as methanolysis. As you can see from the reaction above in Figure F, the reaction also occurs at equilibrium. Both the forward reaction and reverse reaction are polyester producing reactions and are also both known forms of methanolysis.11
Catalysts in Transesterification
To encourage the yield of biodiesel production over the reverse reaction, a catalysts will be needed ensure that as much biodiesel is produced as possible. When transesterification was used to produce soap, the catalysts used were potassium and sodium hydroxide8; but over the last century, other catalysts have been introduced to create higher yields of methyl ester biodiesel in the reaction. Rather than basic compounds, Steven Zheng experimented with acid catalyzation in 2006. His experiment, “Acid-catalyzed production of biodiesel,” was based closely to the design of Canakci and Gerpen, who noticed that basic catalysts would create soap as a byproduct. The presence of a soap would make it extremely difficult to separate the biodiesel from the glycerol produced in the reaction, And so Canakci and Gerpen suggested a new catalyst – sulfuric acid.12
To add onto verifying sulfuric acid as a usable catalyst in transesterification, Zheng also experimented with a new fatty acid source – wasted frying oil. Rather than freshly picked soybean oil or ethanol from corn, Zheng’s experiment used frying oil that had been left over from cooking. Beyond finding that 4% sulfuric acid at 80 degrees celsius reacted the fatty acids most efficiently12, Zheng’s introduction of used cooking oil introduces biodiesel not just as a product that can be produced agriculturally, but also a product that can be recycled from waste. From his findings, products like the Vegawatt have been designed to use wasted vegetable oils to run restaurants.13
Alternative, an organic catalyst has also been found in recent years – a lipase fungi called Candida antarctica. As an immobilized enzyme, Candida antarctica has the benefit of not being temperature dependent or have any detrimental influence from water. In the case of acid and base catalysts, the algae needs to be pressed. This mechanical process can take up a lot of energy and even increase the amount of carbon exhaust at an industrial level. Yuji Shimada’s experiment on the Conversion of Vegetable Oil to Biodiesel Using Immobilized Candida antarctica Lipase, found that “water in the mixture decrease the reaction rate but did not affect the equilibrium of the reaction.” Another feature of the Candida antarctica reaction is that the glycerin and methyl ester layers readily separate in the mixture because no other products are produced.14 Candida antarctica can be seen in Figure G.
It still remains to be seen whether sulfuric acid or Candida antarctica has a higher yield of biodiesl. Although both react and show significant signs of improvement form potassium or sodium hydroxide, their yields have never been compared. Zheng’s experiment reacted sulfuric acid with wasted frying oil. Shimada’s experiment reacted C. antarctica with rapeseed and soybean oil. Comparing the two catalysts side by side would be a crucial experiment in deciding the future of biodiesel before being commercially available.
With the reaction in place with incredibly promising catalysts, right animal still remains to be seen. A term used when it comes to alternative energy efficiency is EROI, energy returned on investment. This term essentially means the ratio of usable energy from energy expended. Prior to 2008, US oil and gas has had an EROI of 25:1. This means that if we were to use 10 joules of energy to combust gas, we’re able to use nearly 250 joules from the 10 joules expended. Unfortunately, with advent of the economic crisis, that ratio has dropped to nearly 10:1. An even more unsettling fact is that ethanol based biofuel only has a 1:1 ratio.15
As mentioned earlier, the industrial labor required for transesterification can be incredibly energy expensive. Water needs to be extracted along with other unnecessary and detrimental components that would deter the reaction. Since the mid 1800’s, soybean oil, canola oil and other vegetable oils were used in transesterification. But, in 1978, under the presidency of Jimmy Carter, a new organism was experimented for its candidacy. 3000 types of algae were tested by the Aquatic Species Program and the program found that because algae is such a high yielding plant in terms of its free fatty acids, it could surely replace fossil fuels for both home heating and transportation.16
The yield from algae can vary anywhere from 10 to 100 times more fuel because the percent of free fatty acids in algae can be as high as 70.3% at 25 degrees celsius.17 In addition, algae requires significantly less space than other organisms. The United States Department of energy estimates that only 15,000 square miles would be necessary to grow enough algae fuel to replace petroleum fuel in the United States. This is only 0.42% of the United States map and approximately half the land area of Maine. To grow the same amount of ethanol fuel, we would need almost 7 times the amount of space to harvest corn.18 19 Schematics have been done of algae vats that can be grown on land to avoid damaging the ecology in the ocean. On land, algae can be iron fertilized and sulfur fertilized without any repercussions to its surrounding environment. Figure H below displays the schematics of a what is known as an algae farm, which is where masses of algae are planned on being cultivated one day.
Biodiesel in California
Transportation-based pollution is one of the leading causes of carbon in California. In fact, California has the highest continues to have the highest vehicles-per-capita ratio in the world. For newborns, this is leading to premature birth. For children, this is leading to increases in asthma. And for many Californians, this is leading to the increased risk of sickness and allergies.20 Petroleum diesel powered truck releases on average 7,000 micrograms of particulate matter, which is over 400 times the level our federal government consider healthy.21
Despite these alarming signals, California has adapted to biodiesel the least. In fact, California (along with Main, Massachussets, New York and Vermont) is one of 5 states that still prohibits the sale of diesel-powered cars.22 The reason for such is because standard diesel (petroleum) releases a significant amount of sulfur to petroleum diesel that contributes sulfur, acetaldehyde, acrolein, benzene, 1,3-butadiene, formaldehyde and polycyclic aromatic hydrocarbons and other things.23 Figure I below shows in less detail the level of emissions in biodiesel compared to diesel; but to be specific pure B100 biodiesel releases 67% less hydrocarbons, 48% less carbon monoxide, 47% less particulate matter, 100% less sulfate, 80% less Polycyclic Aromatic Hydrocarbons, 90% nitrated poly aromatic hydrocarbons and 50% less ozone.24 Although its emissions are significantly less, the awareness for biodiesel’s reduced emissions isn’t presence.
In California, private programs have attempted to start some of the first incentives. A privately funded company, Propel Fuels, has offered a $0.03 rebate per gallon for the purchase of at least 500 gallons a month and a $0.05 per gallon rebate per gallon for the purchase of at least 1000 gallons.25 An intercity bus uses approximately 50,000 gallons a month26, which would really help fleet trucks reduce emissions. But, the technology of biodiesel should be commercially available for the public. If a person on spends around $180 on gasoline27, there is no hope for reaching 500 gallons a month.
With the introduction of the electric car or even the hydrogen fuel cell, the argument may be made – why biodiesel then? It is in my opinion that the exclusive dependence on gasoline and diesel produced much of the problem California faced with energy in the late 20th century. Because California residents have felt so accustomed to a particular way of life and because their neighbors and local friends and family have felt accustomed to this same way, the introduction of newer technologies has been extremely difficult and required a lot of funding, incentives and awareness.
As a matter a fact, California almost gave rise to the first low-carbon fuel standard in the world in 2007.28 That same year, the European Union proposed similar legislation and British Columbia soon followed after in 2008.29 30 Governor Schwarzenegger said that the low carbon fuel standard would “reward innovation, expand consumer choice and encourage private investment.”28 Unfortunately, the low carbon fuel standard did none of that because an injunction was filed in December 2011.31
Many Californians protested the institution of biodiesel because it would encourage plant growth within the state of California. Others protested because they believed that even by 2020, California would not be able to meet the standard that proposed the reduction of carbon emissions by 10%.28 Even though both of these postulations would encourage the growth of new development and business, the Judge ruled in favor of blocking the fuel standard. The judge ruled that the state institution of the fuel standard was unconstitutional because the growth of biofuel to help Californians would extend to areas outside California, which is a power exclusive to the federal government.31
The injunction was finally lifted in 2012 after the out-of-state refiners and ethanol companies argued that because they provided solely to California, the injunction discriminated against their business. To put this in another way, the injunction violated the commerce clause of the U.S. Constitution by imposing limits on interstate commerce.32
Since the injunction lift, the future has been looking bright for biodiesel with Alternative Diesel Fuel regulations established February 15th just this past year and the Air Quality Improvement Program (AB 118) on October 8th, which offers a more realistic incentive program that will let biodiesel be more commercially available. On November 7th, AB 118 was passed and has funded two emerging projects that have plans for cultivate 15,000,000 gallons a year in biodiesel once the projects are completed. Community Fuels has received $4,904,375 and Crimson Renewable Energy has received $5,000,000 on their endeavors to make this possible.35 For Californians, the emergence of biodiesel is reaching an exciting time that will hopefully completely eliminate harmful fuels that have plagued California for the last century.
1Demirbas, Ayhan. Biodiesel: A Realistic Fuel Alternative for Diesel Engines. Springer. December 20th, 2007. See Pages 200 – 204.
2United States Department of Energy Energy Efficiency and Renewable Energy: Biodiesel – http://www.fueleconomy.gov/feg/biodiesel.shtml
3Low Temperature Operability of Biodiesel – http://www.dieselnet.com/tech/fuel_biodiesel_lowtemp.php
4Quantification of the Cold Flow Properties of Biodiesels Blended with ULSD – http://www.biodiesel.org/docs/default-source/ffs-performace_usage/cold-flow-database-report.pdf?sfvrsn=4
5Cold Soak Filtration Test – http://make-biodiesel.org/Quality-Testing/cold-soak-filtration-test.html
6How Biodiesel Works: The Cons – http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/biodiesel4.htm
7Biodiesel Fire Safety – http://abovegroundfuelstoragetanks.com/biodiesel-fuel/2011/biodiesel-fire-safety/
8Biodiesel – http://biodiesel.rain-barrel.net/biodiesel
9Biodiesel Production, Properties and Feedstocks – http://www.jstor.org/stable/20541030
10Transesterification of Oil – www.biotech.iastate.edu/wp_single/…/TransesterificationofOilTBG.doc
11Synthesis and Calorific Value of Biodiesel by Methanolysis of Castor and Olive Oils in Admixture – http://www.ajbasweb.com/ajbas/2011/November-2011/874-878.pdf
12Acid-catalyzed production of biodiesel from waste frying oil – http://www.sciencedirect.com/science/article/pii/S0961953405001790#bbib6
13Vegawatt – http://www.vegawatt.com/Vegawatt-brochures/
14Conversion of Vegetable Oil to Biodiesel Using Immobilized Candida antartica lipase – http://link.springer.com/article/10.1007%2Fs11746-999-0067-6
15Oil from Algae? – http://www.jstor.org/stable/10.1525/bio.2011.61.10.2
16How Algae Biodiesel Works – http://science.howstuffworks.com/environmental/green-science/algae-biodiesel.htm
17Biodiesel production from algae oil high in free fatty acids by two-step catalytic conversion – http://www.sciencedirect.com/science/article/pii/S0960852412002842
18A Promising Oil Alternative: Algae Energy – http://www.washingtonpost.com/wp-dyn/content/article/2008/01/03/AR2008010303907.html
19A Replacement for Oil – http://www.chathamdailynews.ca/2008/06/17/a-replacement-for-oil
20California’s Air Pollution Causes Asthma, Allergies and Premature Births – http://discovermagazine.com/2013/julyaug/19-californias-air-pollution-causes-asthma-allergies-and-premature-births#.UqEyHcRDvqd
21Marsa, Linda. Fevered: Why a Hotter Planet Will Hurt Our Health – and How We Can Save
Ourselves. Rodale Books. August 6th, 2013. Page 50
22Biodiesel: Cultivating Alternative Fuels – http://www.jstor.org/stable/4133105
23Diesel Particulate Matter – http://www.epa.gov/region1/eco/airtox/diesel.html
24Bioiesel Emissions – http://www.biodiesel.org/docs/ffs-basics/emissions-fact-sheet.pdf
25California Laws and Incentives for Biodiesel – http://www.afdc.energy.gov/laws/laws/CA/tech/3251
26Meet the Fleet – http://www.intercitytransit.com/about/meetthefleet/Pages/default.aspx
27Gasoline Price Based on Personal Experience / Parent’s Experience
28Air Resources Board Moves to Cut Carbon Use – http://www.sfgate.com/green/article/Air-Resources-Board-moves-to-cut-carbon-use-3243880.php
29Monitoring and Reduction of Greenhouse Gas Emissions from Fuels (Road Transport and Inland Waterway Vessels) – http://www.europarl.europa.eu/sides/getDoc.do?pubRef=-//EP//TEXT+TA+20081217+ITEMS+DOC+XML+V0//EN&language=EN#sdocta5
30Government Brings in Low-Carbon Fuel Bill – http://www2.canada.com/vancouversun/news/business/story.html?id=23e7f256-4ebc-4468-974a-c4219d78b13b&p=1
31Judge Blocks a California Fuel Regulation – http://www.nytimes.com/2011/12/30/us/judge-blocks-californias-low-carbon-fuel-standard.html?_r=2&scp=1&sq=California%20fuel%20standard&st=cse&
32California Low Carbon Fuel Standard Accused of Discriminating Against Out-Of-State Businesses – http://www.huffingtonpost.com/2012/10/16/california-low-carbon-fuel-standard_n_1971819.html
33Alternative Diesel Fuels – http://www.arb.ca.gov/fuels/diesel/altdiesel/biodiesel.htm
34Air Quality Improvement Program (AB 118) – http://www.arb.ca.gov/msprog/aqip/aqip.htm
35Community Fuels and Crimson Renewable Receive CEC Funding to Expand Biodiesel Production – http://www.californiabiodieselalliance.org/