-Dan Wallace, Danbury, CT
Why do you need to know about biofuel handling? End users, governments, and private enterprises are looking for ways to reduce carbon emissions while minimizing capital equipment costs, and the equipment impacted ranges from backup diesel generators to industrial boilers. While the customer needs for this fuel are becoming more pronounced, third party testing agencies, government regulatory bodies, and even manufacturers are rushing to catch up to customer requirements. Five things to consider with biofuel handling are low temperature operability, extended storage requirements, material compatibility, codes and regulations, and fuel properties (viscosity, specific gravity, heating value, etc…).
Low Temperature Operability
In general, biofuels have higher cloud points and pour points compared to traditional fuel oils (e.g. #2 fuel oil). For example, here is comparison of diesel to B100:
Reference: Alleman, Teresa L., McCormick, Robert L., Christensen, Earl D., Fioroni, Gina, Moriarty, Kristi, and Yanowitz, Janet. Biodiesel Handling and Use Guide (Fifth Edition). United States: N. p.61, 2016. Web.
When the cloud point is reached, crystals begin to form in the fuel and may clog strainers, filters, or nozzles. If the pour point is reached, the fuel will gel and will cease to flow. If the user’s application is in a climate where temperatures can drop below the cloud point, it is important to consider adding a heating element to keep the fuel above its cloud point.
Extended Storage Requirements
Because some biofuels such as biodiesel tend to attract water more than diesel or other fuel oils, microbial growth can be a concern for biofuels. It important to implement proper water removal solutions to keep water out of the main storage tank to minimize microbial growth. Typically, a filtration unit with a polisher can accomplish this function. Cloudy biodiesel most likely indicates a microbial growth issue. Note cloudy biodiesel pictured on the right.
Most biofuels are not compatible with rubber elastomers. Elastomers such as Buna-N, Nitrile Rubber, and EPDM should be avoided. Viton and Teflon are acceptable replacements for fuels such as biodiesel. In addition to elastomers, metallic compatibility must also be checked when considering use of a biofuel. For instance, if fuels such as biodiesel are exposed to yellow metals such as copper or brass for extended periods, sediment may develop in the fuel which could plug filters or nozzles. For some corrosive biofuels, stainless steel may be required.
Codes and Regulations
It is important to consider national and local codes when contemplating a biofuel project. Third party agencies like UL test products to standards related to different fuel types. Due to the concern for fuel spills, the EPA regulates underground storage tanks per Federal Regulations Title 40, Subtitle 1 Subchapter 1 Parts 280-282. In these regulations, the EPA institutes rules for storing biofuels that require reporting and meeting third party requirements such as certification by the manufacturer for the intended fuel. While consulting local and national codes is important, fuel quality and consistency should be verified. Typically, there is an ASTM standard for the fuel such as the ASTM standard D6751 for biodiesel. The fuel manufacturer may also have their own quality metrics for fuel production.
Like the requirements for any other liquid fuel, parameters such as viscosity, specific gravity, and heating value must be considered. Here is a comparison of some common properties for diesel vs. biodiesel:
In conclusion, while five considerations are listed in this publication, there are several other factors to consider before committing to biofuels. It is important to consult equipment manufacturers, local and national codes, and professionals knowledgeable in this subject matter. Although most considerations are subtle, proper equipment and plant design can ensure a successful project.