Vegetable oils and animal fats and their derivatives (biodiesel) are attractive as alternative fuels, extenders and additives for compression ignition (diesel) engines.  Opportunities for biodiesel include off-road markets such as underground mines, marine applications, mass transit (subways, trains) and stationary power generation.  However, research is needed to improve cold start-up and operability, to identify and reduce harmful exhaust emissions (e.g., nitrogen oxides), to develop a rapid and low-cost fuel quality test, and to reduce feedstock and formulation costs.  Development of these technologies will increase market penetration and widespread use of biodiesel.

Problem to be Addressed
The adoption of biodiesel fuel in the United States is hindered by high cost, and the lack of adequate standards and tests.  Before widespread commercialization of triglyceride-based biodiesel fuels and fuel additives are realized, several hurdles must be overcome.  Problems that are addressed by ARS research programs include:  exhaust emissions, fuel quality standards and on-line testing, feedstock costs, cold flow properties, and storage stability. 

Approaches
Combustion and Exhaust Emissions
As with all fuels, biodiesel must meet increasingly stringent exhaust emissions regulations. Especially problematic for biodiesel are nitrogen oxides (NOx) emissions.  Additives, known as cetane improvers, reduce NOx emissions for petroleum diesel fuel.  A similar approach is feasible for biodiesel. Cetane (ignition quality) testing of biodiesel components and of potential cetane improvers as well as engine testing with the identification of exhaust emission levels will provide the necessary technical insights and results to overcome this problem.

Fuel Quality Testing and On-line Process Control
A non-technical impediment to the widespread use of biodiesel is its higher production cost compared to petroleum diesel fuel.  Checking biodiesel fuel quality against current ASTM protocols is time-consuming and labor-intensive.  Rapid, easy-to-use process control and fuel quality analysis can significantly reduce these costs.  Analytical methods tailored to biodiesel fuel and its production will be developed.

Reduce Cost of Feedstocks
Another means to improve the economics of biodiesel is to develop low-cost agriculturally derived lipid materials such as tallow, greases, and soapstocks as feedstocks for biodiesel production. New conversion technology will be required for producing biodiesel from non-conventional feedstocks.

Cold Flow Properties
Biodiesel from nearly all feedstocks has inferior cold flow properties.  This means that engines powered by biodiesel and blends will have operability problems during cooler months in moderate temperature climates.  Fundamental knowledge on phenomena influencing cold flow properties will be acquired and applied.  Cold-solvent extraction, solubilization with surfactants, newly synthesized additives and other approaches will be investigated for its potential to mitigate cold flow limitations.

Storage Stability
The relatively poor oxidative and hydrolytic stabilities of biodiesel are a serious concern with respect to fuel quality during storage.  Factors reducing stability of biodiesel during short and long-term storage need to be identified.  Rapid, sophisticated methods for testing fuel quality under accelerated conditions will ensure fuel quality.  Approaches for improving oxidative stability during storage are needed. 

Intermediate Outcomes
Combustion and Exhaust Emissions
Engine tests will be developed to evaluate cetane improvers, for performance, exhaust emissions, and formulations.  Biodiesel fuel components and cetane improvers will be tested for ignition quality.

Fuel Quality Testing and On-line Process Control
New rapid analytical methods will be developed to monitor biodiesel production, and quality.

Reduce Cost of Feedstocks
New processes will be developed for lower-cost production of biodiesel from vegetable oils and other non-conventional feedstocks.

Cold Flow Properties
Strategies are developed for synthesizing, testing, and field-testing novel compounds as cold flow improvers.

Storage stability
A more accurate lipid quality index will be developed as an alternative to existing indices for predicting oxidative stability of biodiesel fuels.  This will allow phenolic and other antioxidants to be evaluated for their compatibility when mixed with biodiesel/petroleum-diesel blends and for their potential to improve resistance to oxidation. 

Long-Term Outcomes
Combustion and Exhaust Emissions
A biodiesel fuel with reduced exhaust emissions, especially NOx, that will be in compliance with current and future environmental regulations.

Fuel Quality Testing and On-line Process Control
More rapid, cost-efficient, easy-to-conduct analytical methods for assessing biodiesel fuel quality and for the on-line monitoring of biodiesel production.

Reduce Cost of Feedstocks
Feedstocks and new processes that allow production of cost-competitive biodiesel.

Cold Flow Properties
The cold flow operability limiting temperature for biodiesel is reduced by at least 10-degrees Celsius (18-degrees Fahrenheit).  The cold flow operability of 20-percent biodiesel/petro-diesel blends (B-20) improved to a level equivalent to that of petro-diesel.  Cold flow improvers that inhibit crystal nucleation in biodiesel fuels are identified.

Storage Stability
Reasonable conditions are established for handling and storage of biodiesel and blends to safeguard compliance with industrial fuel specifications.  Methods and instrumentation for evaluating oxidative stability of biodiesel under accelerated conditions are developed.  Analytical methods are developed to track fuel quality of biodiesel during short- and long-term storage.

Impact
Biodiesel fuels from agricultural lipid sources which are more uniform, environmentally beneficial, and cost-competitive

Linkages
Other ARS Biofuels programs
Other ARS grain and oilseed utilization programs
ARS Soils and Crops programs
USDA programs:  CSREES, OCE/Office of Energy Policy & New Uses
U.S. Dept of Energy/National Renewable Energy Laboratory

ARS Locations for This Work
Peoria, Illinois and Wyndmoor, Pennsylvania