Biodiesel has better lubricating properties than today's lower viscosity diesel fuels. Biodiesel addition reduces engine wear increasing the life of the fuel injection equipment that relies on the fuel for its lubrication, such as high pressure injection pumps, pump injectors (also called unit injectors) and fuel injectors.
The calorific value of biodiesel is about 37.
27 MJ/L. This is 9% lower than regular Number 2 petrodiesel. Variations in biodiesel energy density is more dependent on the feedstock used than the production process. Still these variations are less than for petrodiesel. It has been claimed biodiesel gives better lubricity and more complete combustion th
us increasing the engine energy output and partially compensating for the higher energy density of petrodiesel.
Biodiesel is a liquid which varies in color — between golden and dark brown — depending on the production feedstock. It is immiscible with
water, has a high boiling point and low vapor pressure. *The flash point of biodiesel (>130 °C, >266 °F) is significantly higher than that of petroleum diesel (64 °C, 147 °F) or gasoline (−45 °C, -52 °F). Biodiesel has a density of ~ 0.88 g/cm³, less than that of water.
sel, the current industry term for diesel produced from petroleum. Biodiesel has high lubricity and virtually no sulfur content, and it is often used as an additive to Ultra-Low Sulfur Diesel (ULSD) fuel.
Biodiesel is made from renewable fats and
oils, such as vegetable oils, through a simple refining process. One of the main commodity sources for biodiesel is soybeans, a major crop produced by almost 400,000 farmers in 29 states.
A variety of oils can be used to produce biod
iesel. These include:
- Virgin oil feedstock; rapeseed and soybean oils are most commonly used, soybean oil alone accounting for about ninety percent of all fuel stocks in the US. It also can be obtained from field pennycress and Jatropha other crops such as mustard, flax, sunflower, palm oil, hemp (see List of vegetable oils for a more complete list);
- Waste vegetable oil (WVO);
- Animal fats including tallow, lard, yellow grease, chicken fat, and the by-products of the production of Omega-3 fatty acids fr om fish oil.
- Algae, which can be grown using waste materials such as sewage and without displacing land currently used for food production.
Global biodiesel production reached 3.8 million tons in 2005. Approximately 85% of biodiesel production came from the European Union.
In the United States, average retail (at the pu
s petrodiesel. B99 and B100 generally cost more than petrodiesel except where local governments provide a subsidy.
Biodiesel is commonly produced by the tran
sesterification of the vegetable oil or animal fat feedstock. There are several methods for carrying out this transesterification reaction including the common batch process, supercritical processes, ultrasonic methods, and even microwave methods.
EPA Registration and Health Effects
All fuels and fuel additives must be registered with the US EPA and be subjected to the health effects regulations contained within 40 CFR Part 79. Companies must register their individual fuel products with the EPA in order to legally market the product to the public. In order to register their fuel, companies must either complete the health effects testing requirements using their specific fuel, or make arrangements with an entity which has completed the testing, in order to use the other entity’s data. The National Biodiesel Board has completed the required health effects testing on behalf of the biodiesel industry, and has established criteria to make the testing data available to companies seeking to register their biodiesel with the EPA. Any fuel that does not meet ASTM D 6751 is not considered biodiesel and therefore does not fall under the NBB testing umbrella. Adoption of D 6751 by the FTA will assist EPA and the biodiesel industry in preventing unregistered fuels from being illegally sold as biodiesel.
Chemically, transesterified biodiesel comprises a mix of mono-alkyl esters of long chain fatty acids. The most common form uses methanol (converted to sodium methoxide) to produce methyl esters as it is the cheapest alcohol available, though ethanol can be used to produce an ethyl ester biodiesel and higher alcohols such as isopropanol and butanol have also been used. Using alcohols of higher molecular weights improves the cold flow properties of the resulting ester, at the cost of a less efficient transesterification reaction. A lipid transesterification production process is used to convert the base oil to the desired esters. Any Free fatty acids (FFAs) in the base oil are either converted to soap and removed from the process, or they are esterified (yielding more biodiesel) using an acidic catalyst. After this processing, unlike straight vegetable oil, biodiesel has combustion properties very similar to those of petroleum diesel, and can replace it in most current uses.
A by-product of the transesterification process is the production of glycerol. For every 1 tonne of biodiesel that is manufactured, 100 kg of glycerol are produced. Originally, there was a valuable market for the glycerol, which assisted the economics of the process as a whole. However, with the increase in global biodiesel production, the market price for this crude glycerol (containing 20% water and catalyst residues) has crashed. Research is being conducted globally to use this glycerol as a chemical building block. One initiative in the UK is The Glycerol Challenge.
Promising Future for Mining Industry
MSHA conducted sampling at 31 mines to evaluate the effectiveness of several different control technologies for diesel particulate matter. These control technologies included, among others, using biodiesel fuel.
Below are the results of the sampling done at the mines using biodiesel:
Results indicate that significant reductions in emissions and worker exposure were obtained for all biodiesel mixtures. These reductions were in terms of both elemetnal and total carbon. Preliminary results for the 20% and 50% recycled vegetable oil indicated 30% and 50% reductions in DPM emissions and exposures, respectively. Preliminary results for the tests on the 50% blend of new soy biodiesel fuel showed about a 30% reduction in DPM emissions and exposures.
Following the success of the biodiesel tests at Maysville Mine, Carmeuse requested assistance in continuing the biodiesel optimization testing at their Black River Mine. In this test, two biodiesel blends along with a baseline test were made. For each test, personal exposures and the ine exhaust were tested for two shifts. The two biodiesel blends included a 35% recycled vegetable oil and a 35% blend of new soy oil. Preliminary results for both the 35% reccyled vegetable oil and the 35% blend of new soy biodiesel fuel showed about a 30% reduction in DPM emissions and exposures.
Biodiesel is an obvious candidate for use in marine applications.
Independent tests have found that pure biodiesel is non-toxic, readily biodegradable and essentially free of sulfur and aromatics. C16-18 methyl esters are considered biodegradable based on their chemical nature and test data collected for experimentally determined oxygen demand and carbon dioxide production as a percent of calculated theoretical values. C16-18 methyl esters do not show any micro biological inhibition up to 10,000 mg/L.
In tests performed by the University of Idaho, biodiesel in an aqueous solution after 28 days was 95 percent degraded. Diesel fuel was only 40 percent degraded. In a second study done in an aquatic environment (CO2 Evolution), various biodiesel products were 85.5-88.5 percent degraded in 28 days, which is the same rate as sugar (dextrose). Diesel degradation was 26.24 percent.
Biodiesel has a higher flash point - a minimum of 200 degrees versus about 125 degrees Fahrenheit for regular #2 diesel. Biodiesel also offers low-pressure storage at ambient temperatures, handles like diesel and is safer to transport.
Biodiesel blended at a 20 percent rate with petroleum diesel has a lower wear scar than traditional fuel. At the 20 percent blend level, biodiesel shows improved lubricity with low sulfur petroleum diesel containing high or low aromatic levels. Start-up, power, range and cold-weather performance characteristics are similar to diesel. Even low levels of biodiesel (1-5%) with diesel fuel offer superior lubricating properties. Recent test results using the HFRR test showed a reduction in wear scar from 0.61 mm to 0.35 mm using a 1% blend of biodiesel with the base diesel.
Farmers are becoming a strong customer base for biodiesel.
Biodiesel provides an opportunity for farmers to create demand for the crops they grow through on-farm use. Farmers' commitment to biodiesel is reflected in their $25 million investment in the product through checkoff dollars.
The industry has encouraged all farmers to ask their fuel distributors to carry biodiesel in at least a two percent blend (B2). Building demand at a grassroots level is critical to the addition of biodiesel to terminals on a large national scale. Although biodiesel is compatible with existing diesel technology, including diesel tanks and other infrastructure, some petroleum distributors may choose to have separate tanks for biodiesel. Adding those tanks now to meet farmer demand will help ensure that the infrastructure is in place to meet future demand from the general public.
Farmers recognize that biodiesel is a high-quality product to use in their farm equipment. Even low blends of biodiesel like B2 and B5 offer exceptional lubricity, thus slowing engine wear and tear. Plus it is a cleaner-burning fuel that is friendlier to the user and the environment.
Biodiesel for Electrical Generation.
The 6 megawatt biofueled backup power system pictured here was installed for the University of California, Riverside's 2001 pilot program and represented a significant milestone in the effort to reduce emissions from standby emergency generators. As the power crisis in California in 2001 unfolded and forced many facilities to deploy portable diesel generators to protect critical operations against blackouts, Southern States Power Company helped the state reduce harmful emissions that normally are associated with this type of equipment.
Temporary backup petroleum diesel-fueled generators typically operate in emergencies without the benefit of exhaust after-treatment to reduce emissions. Using alternative fuels for these necessary backup power sources is a cost effective method of protecting the environment. Fueled on 100% biodiesel (B100), these generators help reduce emissions compared to petroleum diesel in several key areas. Hydrocarbons, a contributing factor in the localized formation of smog and ozone, and sulfur emissions, a major component of acid rain, are essentially eliminated with the use of B100. The exhaust emissions of carbon monoxide, a poisonous gas, are about 50% lower in biodiesel than carbon monoxide emissions from petroleum diesel. Particulate matter, a human health hazard, is reduced by a third, with the smaller particulates reduced by over two thirds.
The demonstration run of the generators, held in August 2001, clearly showed few signs of the telltale smoke associated with diesel fuel. The operation of the generators was part of the weekly scheduled test run by Riverside Public Utilities to ensure readiness in the case of a blackout.
The three Cummins generators represent the state of the art in compression ignition engine technology, as well as digitally controlled electrical interconnection equipment. Each 16 cylinder, 3,673 cubic inch, 2,922 HP Turbocharged/Low Temperature After-Cooled computer controlled four cycle industrial engine drives a heavy duty brushless four pole permanent magnet type generator capable of outputting up to two million watts of power at 480 volts. Separate transformers for each generator to increase reliability steps up the voltage to match the 12,470 volt electrical grid operated and maintained by Riverside Public Utilities. The three generators, operating at full output, consume almost 450 gallons of fuel per hour. A 55-gallon drum of fuel is consumed in approximately seven minutes. That is the equivalent of half a quart for every second of operation. A Southern States Power Company 5,000 gallon onsite tanker trailer provided enough fuel for over 11 hours of operation. SSPC maintained a local tanker truck with biodiesel ready to roll and replenish emergency generator needs on a 24-hour basis.