Renewable Diesel and its Effect on Tanks, Lines, and Equipment in the Tanks
By
Sam Gordji, Ph.D.
Email: samgordji@egreenee.com
Web: www.egreenee.com
Environmental Consultant and Former
University of Mississippi Assistant Professor
Prepared for
Neste Oil
1
Table of Contents
List of Tables ................................................................................................................................................. 3
Abstract ......................................................................................................................................................... 4
Keywords....................................................................................................................................................... 5
About the Author .......................................................................................................................................... 7
I. The Fabric of Renewable Hydrocarbon Diesel ........................................................................................... 8
A. Summary ............................................................................................................................................... 8
B. Introduction ........................................................................................................................................ 10
C. Background ......................................................................................................................................... 12
D. Chemical Characteristics of Renewable Hydrocarbon Diesel ............................................................. 14
E. Naming of Renewable Hydrocarbon Diesel ....................................................................................... 17
II. Effect of RHD on Leak Detection Equipment .......................................................................................... 18
A. Impact of RHD on Leak Detection Equipment .................................................................................... 18
B. Leak Detection Equipment Testing ..................................................................................................... 27
C. Concluding Remarks............................................................................................................................ 35
III. References ............................................................................................................................................. 36
2
List of Tables
Table 2.1: Properties and Requirements for Fuels ................................................................................ 20-21
Table 2.2: Comparative Fuel Properties...................................................................................................... 22
Table 2.3: N100 Fuel Properties.................................................................................................................. 24
Table 2.4: N100 Fuel Properties.................................................................................................................. 25
Table 2.5: N100 Element Analysis Data ...................................................................................................... 26
3
Abstract
This paper investigates the effect of the renewable hydrocarbon diesel (RHD) on tank systems, the leak
detection equipment installed in the tank and the pipelines associated with the tank systems. This
report has two parts. In the first part the chemical characteristics of the RHD, its storage and distribution
is explained. Several sources were reviewed and a few are mentioned here. Reports from these reliable
federal, state, or non-profitable organizations indicate that the chemical texture of RHD is stable and
contains fewer harmful chemicals than petro diesel or ULSD. It also can be stored for a long time. When
samples of NEXBTL (Neste Oil’s trade name for their RHD) from 2005 were recently examined, their
texture, color and chemical contents were the same as those of RHD that were recently produced.
The second part of this report covers the compatibility of NEXBTL with the leak detection equipment
that is installed in the tank. According to several reports from the California Air Resources Board (CARB),
ASTM and others, RHD is compatible with leak detection equipment in the tank. The compatibility of
these equipments with NEXBTL is studied and reported at the end of the second part of this report.
4
Keywords
ARB/CARB
California Air Resources Board
ASTM
ASTM International, American Society for Testing and Materials
ATG
Automatic Tank Gauging
CARB Diesel
California’s Ultra Low Sulfur Diesel
CCR
California Code of Regulations
CRC
Coordinating Research Council
EGR
Exhaust gas recirculation
EPA
Environmental Protection Agency
Ex
x is percent of ethanol in gasoline, e.g. E10 means 10% ethanol and 90%
gasoline, and so on
FAME
Fatty Acid Methyl Esters
GTL
Gas to Liquid
GTO
Gas to Oil
HDRD
Hydrogenation-derived renewable diesel
HVO
Hydro-treated Vegetable Oil
Iso-paraffin
Saturated hydrocarbon (alkane) with carbon chain containing one or more
branches
MMWG
Multimedia Working Group
NWGLDE
National Work Group Leak Detection Evaluation
n-paraffin
Saturated hydrocarbon (alkane) with straight carbon chain
N100
Neste neat Renewable Hydrocarbon Diesel
Nx
x is percent of NEXBTL in diesel, e.g. N10 means 10% NEXBTL and 90% diesel,
and so on
NEXBTL
Trade name for Neste neat Renewable Hydrocarbon Diesel
5
NREL
National Renewable Energy Lab
RD
Renewable Diesel
RD1-RD6
Six renewable diesel samples analyzed by CRC
RHD
Renewable Hydrocarbon Diesel
Rx
x is the percent of renewable diesel in diesel, e.g. R10 means 10% renewable
diesel and 90% diesel, and so on
Saturated Compound
Is a substance in which the atoms are linked by single bounds. A fully saturated
compound contains no double or triple bounds
Tanks
Both underground and aboveground storage tanks for storing fuels
THC
Total Hydro-Carbon
ULSD
Ultra Low Sulfur Diesel
6
About the Author
A partial listing of Dr. Sam Gordji's academic and industrial publications and other technical
achievements may be found on the webpage: www.egreenee.com. For a specific question on a
particular topic please email Sam Gordji at: samgordji@egreenee.com
7
I. The Fabric of Renewable Hydrocarbon Diesel
Summary
This paper focuses on the effect of the renewable hydrocarbon diesel (RHD) on tank systems
(underground storage tanks, above ground storage tanks, and equipment in the tank such as pumps,
pipelines, and leak detection equipment, etc.). It does not address every fuel that someone might call
renewable diesel. While the references cited may identify the product as simply renewable diesel or by
various trade names, we believe the fuels being described are renewable hydrocarbon diesel.
Currently most renewable hydrocarbon diesel is produced by hydro-treating vegetable oils or animal
fats. Hydro-treating is a process used in the refining industry to convert traditional diesel fuel to the
ultra-low sulfur diesel fuel (ULSD) that is required for use in today’s cleaner burning diesel engines.
During hydro-treating, in addition to removing the sulfur compounds, the double carbon-carbon bonds
in any olefins in the feedstock are saturated with hydrogen and some aromatic rings are opened to form
more paraffins. When vegetable oils and animal fats that are typically branched or straight chain
molecules are charged to a hydrotreater it de-oxygenates the fatty acids and saturates any double
bonds to produce paraffinic hydrocarbons. Therefore RHD contains essentially no oxygen, sulfur or
aromatics and generally burns more cleanly than diesel fuel that contains higher concentrations of sulfur
and aromatics.
Leak detection equipment measures the activities in the tank. Leak detection systems that are placed in
the tank perform a variety of activities including: detecting a leak, sales, delivery and theft. These
equipments have generally been working properly and reliably when tanks contain diesel.
A report from Equipment World states that ultra-low sulfur diesel (ULSD) is not corrosive1. Furthermore,
the report goes on to say renewable diesel is not corrosive.
Detailed chemical analyses of renewable diesel in general and Neste Oil’s NEXBTL version of RHD in
particular appears in many publications. Some analyses that are directly supported by Neste Oil have
chemically analyzed RHD that Neste Oil has produced and other RHDs in various capacities to compare
with other vegetable/petroleum fuels. For example, tests by NREL show the emissions of NEXBTL and
renewable hydrocarbon oil typically contain smaller amounts of harmful chemicals than CARB diesel.
This study uses data from publications supported by Neste Oil and independent sources having no
vested interest in a particular oil company such as state and federal governments.
Several states, including California, consider RHD comparable to or better than CARB diesel. Statements
similar to the one below are frequently seen in their publications regarding renewable hydrocarbon
diesel. The California Environmental Protection Agency stated in a white paper that a study “showed
1
http://www.equipmentworld.com/ethanol-a-suspect-in-corrosion-from-ultra-low-sulfur-diesel/
8
that renewable and synthetic diesels have comparable or better emission characteristics as compared to
conventional petroleum-based CARB diesel.”
Also from the California Environmental Protection Agency: “Renewable diesel fuels can be expected to
behave in the environment in a manner similar to CARB ULSD2” is a statement that appears in several
publications from the states and federal government. Further, releases of RHD are said to be similar to
CARB ULSD because of their chemical content and similarity in the formulations of the two substances.
This study investigates how various leak detection equipments handle renewable hydrocarbon diesel
and whether these equipments can correctly report possible losses that may occur in an underground or
aboveground storage tanks due to a crack in a tank or faulty pipelines. The long term effects of
renewable hydrocarbon diesel on the equipment in a tank such as probes, pumps, pipelines and other
equipment that come in contact with renewable hydrocarbon diesel are also discussed.
Because structured tank data on the effect of renewable hydrocarbon diesel on the tank and the
equipments in the tank are not available, an analytical comparison is made with similar fuels and their
effect on the equipments in the tank. Also, references are made to publications from states with more
stringent environmental laws such as California who support the storage, distribution and the sales of
RHD. They have indicated the similarities of renewable hydrocarbon diesel to other fuels that have no
adverse effect on the tank and the equipments in the tank.
Although at this time we may not know the effect of renewable hydrocarbon diesel on the leak
detection equipment, as will be seen in this paper, there are many advantages associated with
producing and burning the renewable hydrocarbon diesel that a routine check of some equipment is
worth the cost. It should also be noted that diesel does not have a single formula. Diesel fuel meeting
the ASTM D975 standard is a mixture of hydrocarbons and up to 5% esters. The hydrocarbon portion of
diesel fuel has varying carbon counts and is a mixture of paraffins (alkanes), naphthenes (cyclic
paraffins) and aromatics (cyclic hydrocarbons containing at least one benzene ring). The paraffins in
traditional diesel are indistinguishable from the paraffins in renewable hydrocarbon diesel.
2
http://www.arb.ca.gov/fuels/multimedia/meetings/RenewableDieselStaffReport_Nov2013.pdf
9
Introduction
Renewable hydrocarbon diesel is a relatively new fuel product. Commercial production began in 2007.
Its nomenclature is still evolving. In the literature it is known by a variety of names including simply
renewable diesel and others that represent production processes or brand names. While most
renewable diesel fuels in commerce today consist mainly of hydrogen and carbon, the generic term
renewable diesel could contain non-hydrocarbon molecules for which we have little experience and
data. As renewable diesel’s reputation as a cleaner burning, low carbon, and environmentally friendly
fuel has grown, some have applied the term to fuels that are substantially different from the
hydrocarbon version. Because we simply do not know the composition or properties of these nonhydrocarbon products this paper focuses on renewable hydrocarbon diesel. While the fuels described in
various literature sources may be identified as renewable diesel or by trade names we believe the
sources cited are providing information and data about renewable hydrocarbon diesel.
Renewable hydrocarbon diesel is environmentally friendly and there are many articles on its production
and use. Several articles with different objectives and aims exist on renewable hydrocarbon diesel with
some details. A few of them are published by: Coordinating Research Council (CRC), Cooperative Fuel
Research (CFR), US Department of Energy (DOE), National Renewable Energy (NRE), Oak Ridge National
Laboratory (ORNL), and Pacific Northwest National Laboratory (PNNL). A few states, federal agencies
and some private entities have also studied alternative and renewable hydrocarbon diesel fuels. For
example CRC has thoroughly analyzed renewable hydrocarbon diesel using various machines for
analyzing chemical compounds and different testing methods including those suggested by ASTM and
others to chemically analyze the renewable hydrocarbon diesel and ultra-low sulfur diesel (ULSD) in
some details. The samples used by CRC were from six different brands of renewable diesel, four of the
samples were ULSD; another four samples were advanced alternative fuels which consisted of
compounds derived from gas-to-liquids (GTL), shale oils and oil sands. A total of sixteen samples were
tested. Several more references may be copied and viewed from www.egreenee.com.
Chemically, hydro-treated vegetable oils (HVOs) are mixtures of paraffinic hydrocarbons. They are free
of sulfur and aromatics because of the method of production. Their carbon range is usually between
C10-C20 depending on the manufacturers’ requirements and the feedstock selected.
There are several methods of producing RHD. Most RHD is currently produced by hydrotreating
vegetable oils, animal fats and waste greases. The hydrotreaters are very similar to those used by
petroleum refiners to reduce the sulfur and aromatic content of traditional diesel fuel to produce ultra
low sulfur diesel (ULSD) fuel. Hydrotreating these oily biomass feedstocks removes oxygen, double
bonds and most trace contaminants and produces paraffinic hydrocarbons. A second method for
producing RD involves a series of reactions of enzymes that results in the production of hydrocarbons. A
third popular method is combusting a biomass source in order to yield carbon monoxide and hydrogen
gas. These two products then undergo a series of reactions which yield liquid hydrocarbons3.
There are several major companies that are currently involved in producing renewable hydrocarbon
diesel while many more may begin to produce renewable hydrocarbon diesel in the near future. There is
a need to educate both the public and public officials in charge of policy making concerning the behavior
3
Multimedia Working Group. "Multimedia Evaluation of Renewable Diesel." California Environmental Protection
Agency., Nov. 2013
10
of this product and its possible use in a variety of diesel engines, from boats to trucks and trains. In
2012, the global renewable diesel production capacity was 0.74 billion gallons per year4.
As stated previously, there are several methods to produce renewable hydrocarbon diesel (RHD).
Therefore, different manufacturers will have a slightly different formula for their RHD. Because of this,
each manufacturer will define their product by a slightly different name. One of the common and more
widely known names is: hydrogenation-derived renewable diesel (HDRD) also known as renewable
diesel (RD). RD is the product of fats or vegetable oils refined by a hydro-treating process. This fuel is
sometime called “non-ester renewable diesel” because it does not contain esters and it helps to
differentiate it from biodiesel that must contain esters and meet ASTM D6751 Specification for Biodiesel
Fuel Blend-stock (B100) for Middle Distillates. Referring to renewable diesel (RD) as renewable
hydrocarbon diesel (RHD) enhances that differentiation as well as differentiates RHD from other
renewable products that are neither esters nor hydrocarbons that someone might want to use in a
diesel engine. There are a few other definitions, and new ones are still evolving because manufacturers
want to make a more precise definition that clearly distinguishes RHD from other fuels. At this time
different agencies with different interests have slightly varying definitions for renewable diesel that
typically require the product to consist mainly of hydrocarbons. The hydrocarbon requirement makes
RHD more like traditional diesel fuel that consists mainly of hydrocarbon and no more than 5% biodiesel.
Eventually a simple and clear definition will emerge for renewable hydrocarbon diesel representing its
content and distinguishing it from other fuels, further a name that consumers would like and easily
accept. The more quickly this occurs will increase the likelihood of RHD becoming more of a household
name. However, because we are discussing its impact on transportation, storage and leak detection
equipment we are focusing on renewable hydrocarbon diesel as a name and description because we
have many years of experience with how hydrocarbons interact with this equipment,
4
Lambert, Natalie. "Study of Hydrogenation Derived Renewable Diesel as a Renewable Diesel Fuel Option in North
America." Eco-Ressources Consultants, 30 Mar. 2012. Web.
11
Background
In 1990, the Environmental Protection Agency (EPA) published seven documents regulating the leak
detection and the sale of petroleum products5. The owners and operators of the fuel stations are
required to check for leaks on a routine basis using one of a number of detection methods mentioned in
the seven protocols originating from the EPA’s underground storage tank regulations6. In order to
ensure the effectiveness of these methods, the EPA set minimum performance standards for equipment
used to comply with the regulations.
The seven protocols cover the test procedure to evaluate the release of the petroleum products from
the USTs or from the pipelines connecting the tanks and carrying the fuels to the dispensing pumps and
other locations. These documents also include a wide variety of leak detection testing requirements for
tanks and pipelines. The test procedure is designed to evaluate these systems against the performance
standards in EPA's underground storage tank regulations, which cover an hourly leak detection test, a
monthly monitoring test, and a line tightness test. For example, after December 22, 1990, all automatic
tank gauging (ATG) systems must be capable of detecting a 0.20 gallon per hour leak rate with a
probability of detection of at least 95% and a probability of false alarm of no more than 5%.
In order to comply with these regulations tank owners and operators installed a variety of leak detection
systems to monitor the activities in the tank as well as the sales and the delivery of their petroleum
products. Originally these leak detection equipments were required to report sales, delivery, and any
possible leak. Later additional components were added to the leak detection equipments enabling them
to report the amount of the water at the bottom of the tank as well.
EPA recommends three methods for the manufacturer of the leak detection device to show their
equipment meets or surpasses the detection limits set by EPA:
1. Evaluate the method using EPA's standard test procedures for leak detection equipment.
2. Evaluate the method using a national voluntary consensus code or standard developed by a
nationally recognized association or independent third-party testing laboratory.
3. Evaluate the method using a procedure deemed equivalent to an EPA procedure by a nationally
recognized association or independent third-party testing laboratory.
Before a new leak detection technology is installed in a tank by the owner/operator, it should be tested
by a third party and approved by the National Work Group on Leak Detection Evaluation (NWGLDE).
There is a list of approved leak detection systems on the NWGLDE website.
NWGLDE consists of a group of state and federal regulators that review leak detection evaluations and
determine if each evaluation was performed in accordance with an acceptable leak detection test
method and meets the EPA protocol. NWGLDE also examines new evaluation protocols and other issues
affecting the leak detection and underground storage tanks (UST) industry.
The new technologies require passing test protocol to ensure they comply with the standard set by the
EPA. These could be some combination of the seven protocols mentioned or a new protocol for new
5
“Standard Test Procedures for Evaluating Leak Detection Methods," EPA/530 UST90/001-7, March to October 1990.
6
“40 CFR Part 280, Subpart D”.
12
fuels such as ethanol blends and ethanol, biodiesel blends and biodiesel, renewable hydrocarbon diesel
and blends and potential fuel products that are simply unknown at this time.
In the past, leak detection equipment has withstood a variety of fuels, from traditional gasoline and
diesel that were essentially all hydrocarbons that had been derived from petroleum to fuel products
that contain non-hydrocarbon (usually oxygenated) blend-stocks and hydrocarbons derived from nonpetroleum sources. Recently, there have been some reports that gasoline that contain more than 20%
ethanol by volume may be damaging to the leak detection equipment. This has created the question,
what impacts will higher concentrations of these and other non-traditional fuels have on leak detection
equipment? Since RHD is fairly new, let’s address that question.
“Renewable diesel is produced from non-petroleum renewable resources, but it is not a mono-alkyl
ester. RD consists solely of hydrocarbons and meets the California Air Resources Board (ARB) motor
vehicle fuel specifications under title 13, California Code of Regulations (CCR), section 2281 et seq. In
fact, renewable diesel meets specified aromatic, sulfur, and lubricity standards, as well as ASTM
International standard specification, ASTM D975-12a.7.”7
Because RD is fairly new, there is not much tank inventory data on how leak detection equipment
measures the activities in the tank containing RD. Petroleum diesel has been widely used for many years
in different climates and is chemically similar to renewable diesel. We look into similarities of the two
fuels as well as their differences. A few specific characteristics we would like to investigate that differ
between the two are the densities and the lack of sulfur content in RD and whether these could cause
malfunctioning of the leak detection equipment and inaccurate reporting of the liquid level.
If the lack of sulfur is a problem for existing equipment, the industry may have a significant problem as
ultra low sulfur gasoline and diesel fuels are being mandated. In order to provide a compliance margin
for the mandated sulfur levels at the consumer level there will be fuels and fuel components in the
distribution infrastructure that contain essentially no sulfur. Equipment that requires sulfur
contamination to function will need to be modified, replaced or dedicated to high sulfur fuel
environments.
While it would be interesting to measure the Volume Correction Factor (VCF) of renewable hydrocarbon
diesel doing so may not significantly improve the accuracy of temperature correction factors for this
fuel. Figure 1 illustrates how the VCF from ASTM table 54B for a 38 to 15o C (approx. 100 to 60o F)
temperature correction. Low gravity distillate fuels like RHD typically contain little or no aromatics. As
the aromatics content increases diesel fuel gravity increases because aromatics are denser than
paraffins. The R2 (0.92) of a linear correlation of % aromatics Vs density is not bad when one considers
that the there are multiple test methods to determine % aromatics and the gravity/aromatic data points
were gathered from random multiple sources. The fact that gravity appears to be a function of
composition and that VCF varies with gravity suggests that the existing volume correction factors are
adequate.
Figure 1
7
Multimedia Working Group. "Multimedia Evaluation of Renewable Diesel." California Environmental Protection
Agency., Nov. 2013
13
Chemical Characteristics of Renewable Hydrocarbon Diesel
There are many publications on renewable diesel by several national agencies such as National
Renewable Energy Lab and Oak Ridge National Lab. There are also some publications on renewable
diesel by universities and states, a partial list for these publications may be downloaded from
www.egreenee.com. Those published by ASTM may be purchased from ASTM. Some partial ASTM
publications may legally be downloaded from the internet.
It seems that the most comprehensive and complete report on comparison and testing of different
diesel fuels is reported by: “CRC Report No. AVFL-19-2”. All publications on RD, whether they are by a
private entity or supported by individual oil companies promoting their product or published by
different states or federal government, strongly support the production and the use of the renewable
diesel. The agencies from the state of California that are in charge of clean air and water are supporting
the production and the use of renewable diesel hoping to minimize the contamination damages that are
caused by the release of the petroleum products, not to mention the emission of the harmful gases
(NOx) from diesel engines.
Renewable hydrocarbon diesel is closer to traditional diesel in chemical formulation than it is to
biodiesel, because part of the fabric of biodiesel contains oxygen and double carbon-carbon bonds. The
other two fuels contain a few if any molecules with double carbon-carbon bonds or oxygen atoms.
Due to similarities that exist between diesel and renewable hydrocarbon diesel, for example, both
follow Pascal's law, and their densities are similar to one another, renewable diesel should behave much
like diesel when under pressure. Because the density of RHD is less than that of diesel, there may be
need for some small adjustments to the probes measuring the activities in the tank. Due to the
similarities in the formulation and the chemical structure of the two fuels, the coefficient of the thermal
14
expansion for RD should be close to that of diesel, which is about 0.00046 °F, or 0.000824 °C8. What
differences there may be are probably taken into account in the ASTM Table 54B volume correction
factors that are a function of product gravity and temperature.
Because most analyses and tests show that RHD is chemically similar to CARB diesel, their effect on
delicate tank equipments will be similar to traditional diesel, and they should not harm the sensitive
equipments.
Below is a summary of a few properties of RHD, as well as its storage, distribution, and dispensing.
1. RHD is compatible with existing fuel distribution systems9. RHD and blended RHD can be
distributed through modern infrastructure and transported through existing pipelines for
dispensing at fueling stations2.
2. RHD is considered alternative diesel fuel. Testing by some agencies indicates that RHD contains
99.97 wt% of hydrogen and carbon. This hydrocarbon content is greater than that of other
ULSD’s that are presumed to be hydrocarbon oil as defined in and required by ASTM D975.
3. Over a dozen refineries in various countries such as Finland, Singapore and Ireland have been
producing RHD commercially as early as 2006. In the US, several oil companies are producing or
plan to produce RHD. Two joint ventures, one formed by Syntroleum and Tyson and another
formed by Valero Energy and Darling have started up and several other have been announced.
Worldwide, Neste Oil a Finnish refiner is the largest RHD producer.
4. Naming of RHD is similar to other fuels, for example R100 means the renewable hydrocarbon
diesel fuel containing 100% RHD.
5. In the Energy Policy Act of 2005, the IRS ruling appeared to allow tax credit for production of
renewable diesel that may or may not be renewable hydrocarbon diesel.
6. Renewable hydrocarbon diesel contains a higher cetane number than petro diesel. In North
America, most states use ASTM D975 as their diesel fuel standard and the minimum cetane
number is set at 40, with typical values in the 42-45 range.
7. The cetane values for the GTL and most renewable hydrocarbon diesels (RD1, RD2, RD4, Neste
RHD) are greater than 70 and are significantly higher than other fuels. These high values are
typically obtained for diesel fuels that have high concentrations of n- and/or iso-paraffin10.
8
This requires further studies for finding the exact coefficient of thermal expansion for RD for getting a precise
volume reading in a UST
9
http://www.afdc.energy.gov/fuels/emerging_green.html
10
CRC Report No. AVFL-19-2
15
8. Some analyses indicate the amount of sulfur and aromatics in RDs are essentially zero, while
others report the amount is close to zero. RHD can be easily blended with other fuels such
traditional diesel or bio-diesel.
9. Testing showed emissions of gases (CO and NOx) from the exhausts of a 2006 international 6.0
liter V8 were significantly lower than conventional diesel for all varieties of beef, canola, poultry
fat, etc. used to produce RD11.
10. Paraffin, also known as an alkane, is any saturated hydrocarbon having the general formula
CnH2n+2. RHDs are a mixture of paraffinic hydrocarbons and can be arranged in either straight
chains (n-paraffin, such as butane; see figure below) or branched out chains (iso-paraffin).
(Hydrocarbon molecules are like Tinker-Toys one can draw diesel boiling range molecules just by
simply inserting more H-C-H groups between two carbon atoms or between carbon and
hydrogen atoms.) Most of the paraffin compounds in crude oils are normal paraffin, while isoparaffin (that has better cold weather storage and handling properties than n-paraffin) is
frequently produced in refineries to enhance cold weather properties. While petroleum diesel
contains mostly n-paraffin, diesel obtained from renewable sources is mostly made up of isoparaffin because the conversion processes are similar to those used in the refining industry to
produce iso-paraffin and because better cold weather storage and handling properties are
desirable. Both iso-paraffin and n-paraffin have good diesel engine combustion characteristics.
Below are the chemical structure of n-paraffin and iso-paraffin12.
11
Renewable Diesel Subcommittee of the WSDA Technical Work Group
https://www.google.com/search?q=plot+of+branched+chains+%28isoparaffin%29&source=lnms&tbm=isch&sa=
X&ei=KR0iU9zEN4O42wXe0YDQBQ&ved=0CAgQ_AUoAg&biw=893&bih=536&dpr=0.9
12
16
Naming of Renewable Hydrocarbon Diesel
Most of the literature, research and government approvals concerning renewable diesel have
actually been addressing renewable hydrocarbon diesel. By defining renewable hydrocarbon diesel
as:
“Renewable hydrocarbon diesel n. - hydrocarbon oil derived from biomass that with
the addition of chemicals to enhance performance, if required, conforms to the
requirements of ASTM D975-14 Standard Specification for Diesel Fuel Oils,
and meets the registration requirements under 40 CFR part 79.”
The NWGLDE can rely upon the chemical similarities between traditional diesel fuel and renewable
hydrocarbon diesel and various statements from EPA, ASTM, states, and national labs to allow
renewable hydrocarbon diesel to be used with all equipment listed for diesel.
17
II. Effect of RHD on Leak Detection Equipment
A. Impact of RHD on Leak Detection Equipment
In the first part of this report the chemical structure and the production of RHD was explained.
In these next few sections, the effect of RHD on tanks and the equipment in the tanks such as probes,
pumps, as well as the peripheral parts which include pipelines will be discussed. These systems have
been installed in tanks in the US since the beginning of the 1990s and have worked with a variety of
fuels (gasoline, kerosene, jet fuel, diesel fuel, etc.). Originally, the predominant component of these
fuels was hydrocarbon oil derived from petroleum. Probes were developed to accurately report water
intrusion and/or any loss of product.
Fuels other than petroleum-based hydrocarbons have been introduced to the market and
different federal and state agencies are interested in their effects on tank equipment. These rather new
fuels can be classified into two groups: hydrocarbon and non-hydrocarbon. Non-hydrocarbons include
ethanol (an alcohol) derived from corn and sugar cane that is added to the gasoline-based fuels for
consumption in spark ignition engines, biodiesel (a mixture of fatty acid esters) derived from vegetable
oils and animal fats that is added to diesel fuel for use in compression ignition engines and some more
recently developed fuel components such as bio-butanol and possibly others. The impact of these nonhydrocarbon fuels on tanks and the equipment in the tanks such as probes, pumps, as well as the
peripheral parts which include pipelines is not addressed in this document. This document focuses on
renewable hydrocarbon diesel that is produced from renewable resources and intended for use in diesel
engines.
The majority of the leak detection equipment is installed in tanks containing hydrocarbons
derived from petroleum and there have not been many reports of equipment failures. Renewable
hydrocarbon diesel has been in commerce since 2006 at concentrations ranging from a few percent to
100%. There have been no reports of equipment failures attributed to its presence.
The leak detection equipment can accurately report the dispensing and delivery of the product if
they are not affected by the content of the fuel or by the chemicals that might have been added to the
fuel for various reasons. One cause for equipment malfunctioning in the tank is due to the chemical
reactions that occur as a result of the different chemicals that are present in the tank.
The accurate reporting of the leak detection system is assured when the tank has not corroded
and the leak detection systems are not harmed in anyway. Corrosion in the tank, in the lines or on the
leak detection equipment usually occurs when there is a sufficient presence of oxygen, water or alcohol
in the tank.
Water is the number one solvent and alcohol is the number two solvent. Since the molecular
formula for RHD does not contain oxygen, it therefore contains no alcohol or esters. RHD does not have
18
affinity for water, so it can be concluded that leak detection equipment installed in a tank will not be
adversely affected by disintegration and conversion of RHD to another substance
In the following paragraphs, we have gathered short articles, tables, and data from various
sources to compare RHD with other fuels such as petroleum diesel and bio-diesel. From every test
conducted by federal, state agencies, or national testing centers, we have found that the amount of
undesirable substances, chemicals that are harmful to the tanks and to the tank equipment’s, are rare in
RHD. The analysis of RHD revealed the amount of harmful chemicals is less than those in petroleum
diesel, bio-diesel or FAME. To save space, we have only reported a few of those findings obtained by
different testing agencies. A few of those sources are mentioned here, but readers are referred to their
original URL if they are interested in more detailed information for explaining the behavior of RHD.13
When stored samples of NEXBTL from 2005 were recently analyzed, the texture, the content
and the color of NEXBTL were the same as those produced recently. Those samples will be kept and will
be tested again in the future to ensure that the formula and the texture of NEXBTL remains the same.
The chemical formulas for RHD are very similar to the petroleum diesel. Since there have not
been any reports of equipment failures in Europe or elsewhere in tanks containing up to 100% by
volume of RHD, it is enough to consider RHD environmentally safe without having an adverse impact on
the tanks and on the leak detection equipment. Unlike traditional diesel, RHD, as mentioned in the first
part of this document, is almost free of harmful chemicals such as sulfur, CO2, trace metals and a few
other substances that are known to have some adverse effect on the leak detection equipment. Because
of their similarities to traditional diesel and the lack of harmful chemicals in their formulas any leak
detection equipment that is already installed in tanks carrying traditional diesel there is no RHD property
based reason to limit RHD content in existing diesel tankage.
Generally European regulators permit the use of new products before US regulators permit the
use of the same or similar products for consumers to use. Neste Oil has been blending NEXBTL with
petroleum diesel in pilot plant quantities since 2005 and in commercial quantities since 2007 at
concentrations ranging from a few percent to 100%. In Europe the diesel fuel standard EN590 has a
minimum gravity requirement that limits RHD content to the 50% to 60% by volume range. The US
standard ASTM D975 does not have a minimum gravity standard which allows diesel fuel containing up
to 100% RHD to meet the standard. During distribution, RHD concentration starts at 100% and then is
usually diluted with conventional diesel fuel to levels as low as or less than 5%. There has not been any
report of equipment failures or damages on the equipment due to corrosion caused by NEXBTL or
changes in the chemical formulation of NEXBTL. We have no experience that indicates RHD blends that
meet prevailing diesel fuel standards causes problems with existing distribution infrastructure.
13
www.egreenee.com
19
The similarities and the differences of petroleum diesel and NEXBTL were discussed in some
details in part one of this document. As previously stated, neither petroleum fuel nor RHD contain
oxygen nor have affinity for water. They also have similar chemical formulas.14
Table 2.1: Requirements for fuels and properties of biodiesels (From Table 3 of VTT-R-07049-08_GB)
Diesel, summer
FAME
Data on analysis HVO
grade (EN
EN14214:2004
of an RME
(NEXBTL)
590:2004)
Ester content, %vol
max 5
min 96.5
>98.7
Boiling point, °C
to 360
Density / 15°C, kg/l
Viscosity @ 40 °C,
mm2/s
0.820-0.845
2.0-4.5
Cloud point, °C
Max -5
0.860-0.900
3.50-5.00
Pour point, °C
347
250to 310
0.8835
4.5
0.7780
2.9 to 3.5
0
-5 to -30
-13
CFPP, °C
Max -15
Flash point, °C
>55
min. 120
>178
>60
Residue of combustion,
%wt
<0.30
max. 0,30
<0.1
<0.30
Ash, %wt
<0.01
max. 0.02
<0.01
<0.001
Sulphur, mg/kg
<50
max. 10,0
<1
0
Cetane number
>51
min. 51.0
<51
84 to 99
Thermal value, gross,
MJ/kg
44
40.54
44
Copper corrosion
class 1
class 1
1
Water content, mg/kg
max 200
max. 500
250
max 24
7
Oxidation resistance,
110oC, h
min. 6
>6.3
Phosphorous, mg/kg
max. 10.0
0.5
Acid value, mg KOH/g
max 0,50
Iodine value
max. 120
Contaminants, mg/kg
Oxidation resistance,
g/m3
14
max 25
<113
DynamicFuelsfaq.html
20
Acid number TAN, mg
KOH/g
max. 0.50
0.17
Free glycerol, %wt
max. 0.02
<0.004
Glycerol, %wt
max. 0.25
0.18
Monoglycerides, %wt
max. 0.80
<0.01
Diglycerides, %wt
max. 0.20
0.16
Triglycerides, %wt
max. 0.20
0.07
Methanol, %wt
max. 0.20
<0.01
Na+K, mg/kg
max. 5.0
<2.6
Ca+Mg, mg/kg
max. 5.0
<0.5
Linolenic acid ME
max 12.0
<9.5
>4 double bonds
max. 1
<1
Table 2.1 above represents some of the chemical makeup of diesel, FAME and NEXBTL. As
reported in table 2.1 the presence of harmful substances to tank equipments and environment are
smaller in NEXBTL than they are in diesel or FAME. Also, as noted above, NEXBTL is almost free of sulfur
and its gross thermal value is higher in comparison15.
Below is a phrase from a White Paper prepared by California Environmental Protection Agency
on renewable diesel16: “Staff also recognizes that new innovative hydrocarbon-based diesel fuel
substitutes, like renewable and synthetic diesels, are also available in the market and could be
addressed in this rulemaking. However, the physical properties of renewable and synthetic diesels meet
all applicable petroleum diesel fuel quality requirements under 13 CCR 2281-2285. Therefore, the staff
believes that it would be appropriate to allow the use of compliant hydrocarbon-based renewable diesel
and synthetic diesels either as neat fuels, or as blend-stocks in the production of conventional
petroleum CARB diesel fuel under 13 CCR 2281-2285. The CARB biodiesel/renewable diesel study
showed that renewable and synthetic diesels have comparable or better emission characteristics as
compared to conventional petroleum-based CARB diesel.”
Paragraph 2 and 3 below are also from the State of California Environmental Protection Agency:
“2. Underground Storage Tank Material Compatibility and Leak Detection California statutes
require that the underground storage tank systems be compatible with the substance stored, and the
leak detection equipment be able to function appropriately with the substance stored. The multimedia
15
16
VTT-R-07049-08_GB
RenewableDieselStaffReport_Nov2013
21
evaluation indicates that renewable diesel is chemically comparable to CARB diesel. Therefore,
differences in compatibility and leak detection are not anticipated.
3. Biodegradability and Fate and Transport UC Davis and UC Berkeley researchers provided data
on the impacts of fate and transport properties of renewable diesel compared to CARB diesel. Fate and
transport, as well as biodegradability, are not expected to be significantly different given the similar
chemical composition of renewable diesel and CARB diesel”.
Table 2.2 below is also from California Environmental Protection Agency (CEPA) comparing the European
ultra-low sulfur diesel fuel with NEXBTL (Table 4.2 of CEPA)
Table 2.2 (from table 4.2 16): Comparative fuel properties for conventional low-sulfur diesel
and a HRDF (NEXBTL) (Rothe, et al., unpublished document).
Units
EN590*
NEXBTL
Fuel Property
Density @ 15°C
Viscosity @ 40°C
Sulfur Content
kg/m3
833
783
mm2s-1
mg/kg
2.35
3.4
6
<1
1.86
2.1
CHx
IBP**
°C
171
216
FBP***
°C
364
321
%vol
24.9
<0.02
49.7
97.9
Total Aromatics
Cetane Index
*European ultra-low sulfur diesel fuel
**Initial boiling point
***Final boiling point
Table 2.2 shows that NEXBTL has lower sulfur than European ultra-low diesel fuel.
Below are some quotes from the State of California Environmental Protection Agency that
explain in detail the chemical composition of NEXBTL.17
“The chemical composition of the resulting pure R100 is a combination of straight and
branched chain paraffins or alkanes. Neste has determined the chemical speciation of the pure R100
using gas chromatography and mass spectrographic analysis”.
17
RenewableDieselStaffReport_Nov2013
22
The carbon numbers range from C10 to C20 and the boiling point range are from 120°C to 320°C.
These values are within the range of conventional diesel. Other analyses indicate Neste’s NEXBTL
consists of n- and iso-parrafins (Rantanen, et al, 2005) and contains very low amounts of poly- aromatic
hydrocarbons, oxygenated compounds and sulfur. In 2005, VTT Processes in Finland conducted physical
properties characterization tests on Neste’s fuel (Rothe, et al., unpublished document). The fuel was
produced from vegetable oils (canola/rapeseed or palm oil). Table 2.2 summarizes the reported fuel
properties of R100 fuel produced by Neste, NEXBTL. The NEXBTL fuel was found to be similar to the
European Union’s EN590 and Sweden’s EC1 ULSD equivalent fuels. EN590 does not have an aromatics
requirement but Sweden’s EC1 has a maximum limit of 5% aromatics.
Neste Oil Corporation has also conducted a life-cycle assessment of the energy and greenhouse
gas balance of its R100 NEXBTL fuel (Gartner, et al., 2006). This assessment was conducted using an
approach consistent with the ISO 14040-43 standard. During this analysis, the consumption of nonrenewable energy sources (i.e., non-renewable fossil fuels, natural gas, coal, etc.) and the production of
greenhouse gases (i.e., carbon dioxide, methane, nitrous oxide) were considered. The feed-stocks
considered were rapeseed (canola) and palm oil. “For all comparisons, scenarios and sensitivity analyses
considered, the assessment found that use of NEXBTL R100 saves primary energy and greenhouse gas
emissions over its entire life-cycle when compared to conventional fossil diesel fuel. The biggest
variation in the results was associated with impacts from the production, transportation, and
extraction of the crude plant oils used to make the R100. The rapeseed energy savings ranged from 30
to 33 giga-joule (GJ) primary energy per ton of NEXBTL. The rapeseed greenhouse gas savings ranged
from 1.2 – 2.5 tons of CO2-equivalents per ton of NEXBTL.”
Material Compatibility and Storage Stability for NEXBTL is copied from California Environmental
Protection Agency (CEPA)
“5.1. Material Compatibility and Storage Stability
In general, the handling and storage of renewable diesel that meets ASTM D 975 standards is
the same as for petroleum diesel including the needed protection from ignition sources. Tanks used for
transport and storage must be suitable for combustible liquids and precautions must be taken to
prevent product spills on to the ground, into drains, and into surface and ground waters.
In the evaluation of the multimedia impacts of new diesel formulations, materials compatibility
and storage stability are important considerations, but little information is available on pure renewable
diesel materials compatibility.
5.2. Distribution and Blending of Renewable Diesel
Blended HDRD can be transported via the same methods used for conventional diesel, including
pipelines, rail cars, tank trucks and drums. The choice of transport vessel depends on the quantity of
23
renewable diesel being transferred and the cold flow properties of the fuel. R100 may be blended with
conventional diesel at any volume having a blended product that contains R10 to R100 by volume.
Tables 2.3-2.5 and the text below are copied from “National Renewable Energy Laboratory
(NREL)18.
“The NOx reduction is attributed to the higher EGR rate, due to the resulting increase in
combustion temperature. The reduction in CO is attributed to the higher cetane value of the N 100 as
this fuel has a shorter ignition delay time and thus less premixed combustion will occur, particularly at
low load conditions as were applied during this test.
Table 2.3 (from table 6 of NREL): N100 Fuel Property Data
Percent
ULSD
N100
Change
EGR rate
NOx (ppm)
CO (ppm)
THC (ppm)
Throttle (%)
0.26
251.83
67.44
8.79
27.63
0.27
215.83
58.96
9.85
28.70
2.5%
-14.3%
-12.6%
12.1%
3.9%
Below are some fuel analysis and fuel testing as reported by NREL.
“Fuel Properties
Fuel properties covering the D975 specification for diesel fuels along with several other
properties were determined for the N100 sample; the results of these tests are listed in Table 7. The
Neste renewable diesel fuel met the requirements for No. 2 diesel in ASTM D975. The fuel also shows
excellent thermal and oxidative stability, and is essentially 100% renewable carbon. The mass-basis net
heating value was measured at 3.8% higher than that of the ULSD; however the volume-basis heating
value was measured at 3.3% lower due to the relatively low density of the fuel. In addition to ASTM
specification properties the fuel was tested for anticorrosion properties by N A C E TM 0172. This test is
a pipelining requirement with a minimum rating of B +. The Neste renewable diesel was found to have a
NA C E rating of E, the lowest rating, and would therefore require an anticorrosion additive to meet
pipelining specifications.”
18
Doc 7 NRELT_2estSummaryReportFeb2012
24
Table 2.4 (table 7 from NREL): For N100 Fuel Property Data from NREL
ASTM Test
Method
Property
Derived Cetane Number
Cetane Number
Copper Strip Corrosion
Aromatics
Olefins
Saturates
Cloud Point
Cloud Point
LTFT
CFPP
Sulfur
Water and Sediment
Water
Water Saturation
Kinematic Viscosity
Ash
Carbon Residue
Lubricity: Wear Scar
Diameter
Distillation (T-90)
Flash Point
Conductivity
Heating Value (Net)
Heating Value (Net)
Density
Carbon
Hydrogen
Oxygen
Biobased Carbon Content
Accelerated Stability
Thermal Stability
D6890
D613
D130
D1319
D1319
D1319
D2500
D5773
D4539
D6371
D5453
D2709
D6304
D6304
D445 (40°C)
D482
D524_10%
D6079
D86
D93
D4308
D240
D240
D4052 (15°C)
D5291
D5291
FNAA
D6866
D2274
D6468 (180
minutes)
TM0172
D664
D7371
NACE Corrosion
Acid Value
FAME Content
*
Limits for No. 2 S15 diesel fuel
§
Units
N100
---%
%
%
°C
°C
°C
°C
ppm
vol%
ppm
ppm
cSt
wt%
wt%
74
-1A
<0.1
0.6
99.4
-27
-24.8
-24
-25
1.1
0.01
15
50
2.5
<0.001
0.04
-42.5
-33
1.6
65.4
-24
---8
---2.4
-0.07
ASTM
D975
Limit*
40 min
40 min
3 max
35 max
--Report
Report
--15 max
0.05 max
--1.9 – 4.1
0.01 max
0.35 max
µm
425
612
520 max
°C
°C
pS/m
btu/lb
btu/gallon
g/mL
%
%
%
%
mg/100mL
287
65
113
19,108
123,604
0.7751
84.6
15.19
<0.01
100
0.2
300
76
106
18,413
127,840
0.8508
87.01
12.99
----
282 - 338
52 min
25 min
---------
% Reflectance
100
--
--
-mg KOH/g
%
E
0.02
<0.5
----
--5 max
§
Properties of the ULSD were supplied by the fuel producer
25
“Elemental analysis was conducted by inductively coupled plasma atomic emission spectrometry
following ASTM method D5185. The results of this analysis are listed in Table 8. None of the elements
included in this analysis were detected above the limit of detection for the method.”
Table 2.5 (table 8 from NREL): N100 Elemental Analysis Data of NREL
Element
Result
(ppm)
Al
Sb
Ba
B
Ca
Cr
Cu
Fe
Pb
Mg
<1
<1
<1
<1
<1
<1
<1
<1
<1
<1
Element
Result
(ppm)
Element
Result (ppm)
Mn
Mo
Ni
P
Si
Ag
Na
Sn
Zn
K
<1
<1
<1
<1
<1
<1
<5
<1
<1
<5
Sr
V
Ti
Cd
S
As
Be
Bi
Co
W
<1
<1
<1
<1
<25
<5
<5
<5
<5
<5
26
B. Leak Detection Equipment Testing
RHD is a relatively new fuel with less than 10 years of actual field use. e RHD consists primarily
of paraffinic hydrocarbons that are known to be quite stable and have little affinity for water (a major
cause of tank corrosion problems) and contains essentially no contaminants that are known to cause
tank corrosion. Therefore, there does not appear to have been any direct testing of its compatibility
with tanks and leak detection equipment. At this time all the data we have is that there have been no
reports of storage problems that have been attributed to RHD. While there is no direct test data
available on the effect of renewable hydrogenated diesel on the tanks and leak detection equipment in
the tank, there is, however, a vast amount of references supporting the production and the use of RHD.
Some of these references have been mentioned in the first part of this paper and they include
governmental agencies, non-profitable organizations, universities, etc.
Included below is more evidence that the state of California has evaluated and supports the
production and the use of RHD19: “Renewable Diesel Multimedia Evaluation “Renewable diesel” is
produced from non-petroleum renewable resources and is not a mono-alkyl ester. Renewable diesel
consists solely of hydrocarbons and meets ARB motor vehicle fuel specifications under title 13, California
Code of Regulations, section 2281 et seq. 2 completed their assessment of the renewable diesel
multimedia evaluation and potential impacts on public health and the environment. The evaluation is a
relative comparison between renewable diesel and CARB diesel. Based on the results of the multimedia
evaluation and the information provided in the UC’s Renewable Diesel Final Tier III Report, the MMWG
makes the overall conclusion that renewable diesel specifically evaluated within the scope of the
evaluation will not cause a significant adverse impact on public health or the environment.
Hard copies of the MMWG Biodiesel Staff Report and Renewable Diesel Staff Report, including
the UC Biodiesel Final Tier III Report and Renewable Diesel Final Tier III Report, will be provided. Also, all
references cited in each of the staff reports will be provided electronically on a compact disc.
In summary RHD contains minimal harmful substances such as sulfur, ash, aromatic, COx and
other chemicals and meets all the requirements that are placed on their production, transportation and
use by regulatory agencies. These regulatory agencies have included their approval of the production of
RHD in their publications. These papers include several publications by ASTM, federal and states
governments who set limits on the production and use of various chemicals and fuels. While most of the
publications have been scanned by author for preparing this report, not all the publications supporting
the use and transportation of RHD are mentioned here.
Hard copies of the MMWG Biodiesel Staff Report and Renewable Diesel Staff Report, including
the UC Biodiesel Final Tier III Report and Renewable Diesel Final Tier III Report, will be provided. Also, all
references cited in each of the staff reports will be provided electronically on a compact disc.
19
RenewableDieselStaffReport_Nov2013
27
Below are some of the findings of NREL:
“Overall results show that the Neste renewable diesel was a high quality material which met or
exceeded the minimum properties for ASTM D975 specification for diesel fuel oil in its neat form. ULSD
blended with Neste showed decreased gravimetric fuel consumption due to the higher gravimetric
heating value of N100. The mass-basis net heating value was measured at 3.8% higher than that of the
ULSD, but the volume-basis heating value is 3.3% lower due to the low density of the fuel. Emission
testing with a 2008 model year U.S. on-highway engine equipped with a DPF showed no effect of N5,
N20, or N100 on tailpipe THC, CO, or PM. NOx decreased by 2.6% with N5, 4.0% with N20, and 9.5%
with N100. Engine out smoke number showed no significant change for N20 but was reduced by 34.2%
with N100. Engine combustion studies showed a decrease in ignition delay compared to ULSD due to the
higher cetane value of the N100. At steady state low-load conditions NOx and CO emissions were
decreased by 14.3% and 12.6% respectively. Percent throttle was increase by 3.9% due to the lower
volumetric energy density which resulted in a 2.5% increase in EGR rate.”
NWGLDE has a list of available technologies on their website. The order of the listing and the
technology below is in the same order as the listing of NWGLDE.
Below each technology is mentioned and its working environment under RHD is investigated.
There are many leak detection technologies available in the market for detecting leaks and
monitoring the activities in the tank and in the pipeline using different methods and technologies.
Venders may choose a particular method such as Volumetric System, Non-Volumetric System, etc. for
installation in their tank and monitoring the activities in the tank. In this part of the paper, each
technology is reviewed and the impact of RHD like NEXBTL on it is investigated.
Leak detection equipment is designed to report leaks from the tanks or the pipelines when some
activities is going on in the tank such as delivery or sale and also during the quite times. During the
delivery when the temperature of the product in the tank is different from the temperature of the
delivery leak detection equipment make adjustment to the volume and correct for the temperature
difference. EPA requires that any leaks or an unaccounted loss of product to be reported to the
owners/operators of the UST.
Below, each leak detection technology is mentioned and the effect of RHD is investigated on
them. The order of technologies here follows closely the listing of these technologies in NWGLDE
Website and in many cases the information is from the manufacturer’s website20.
20
http://nwglde.org/method_index.html
28
Above Ground Storage Tank Leak Detection Method (AST):
There are two technologies listed under AST in NWGLDE, they are: mass based system
manufactured by Mass Technology Corporation and Praxair Services, Inc. These build Tracer Tight for
Large Aboveground Storage Tank Systems.
Mass Technology Corp. builds IM-1000 and CBU-1000 which works with: Gas, diesel, aviation
fuel, fuel oil #4. According to manufacturer’s website other liquids may be tested after consultation with
them. Since the chemical composition of NEXBTL is similar to diesel without some of the undesirable
chemicals, the technology should easily handle RHD.
Praxair Services is the manufacturer of Tracer Tight for Large Aboveground Storage Tank
Systems which works with gasoline, diesel, aviation fuel, fuel oil #4, waste oil, crude oil. Other fluids
which are compatible and soluble with an acceptable tracer chemical may be tested after consultation
with the manufacturer. The chemical composition of NEXBTL is similar to paraffins that have been in
diesel fuel since it was first distilled from crude oil and are currently being produced in refineries to
enhance cold weather properties and lower sulfur content. Therefore unless the tracer chemicals are
not soluble in paraffins, this technology should be capable of managing NEXBTL. Should some minimal
aromatics content be required to dissolve the tracer chemical the tracer manufacturer should advise the
user and perhaps update their technology to make sure it still works with today’s diesel fuels that tend
to contain fewer aromatics.
Automatic Electronic Line Leak Detector (AELLD):
There are at least fifteen manufacturer Automatic Electronic Line Leak Detectors. Many of the
manufacturer claim that their detector may be installed in tanks carrying Gasoline, diesel, aviation fuel,
fuel oil #4, solvents, waste oil, biodiesel B6-B20 meeting ASTM D7467, biodiesel B100 meeting ASTM
D6751*, crude oil, petroleum distillates in liquid form, cooling fluids, and water or water soluble
liquids. They indicate other liquids may be tested after consultation with the manufacturer. Other
manufacturers claim their detectors may be installed in gasoline tanks and ethanol blends up to E100.
With such a big variation in the chemical composition which includes B100 and knowing that most of
these fuels contain more harmful chemicals than RHD, the detectors should easily handle RHD.
Automatic Mechanical Line Leak Detector (AMLLD):
There are at least five manufacturers of Automatic Electronic Line Leak Detectors.
Some of the manufacturers claim that their detector may be installed in tanks carrying gasoline,
gasoline-alcohol mixtures, aviation fuel, fuel oil #4, solvents, diesel, biodiesel blends B6-B20 meeting
ASTM D7467, biodiesel, B100 meeting ASTM D6751*. With such a large range of fuels that AMLLD can
handle including B100, AMLLD can cover RHD.
29
Automatic Tank Gauging Method (ATGM):
There are more than twenty five manufacturers of ATG. Some of the major manufacturers
claim that their detector may be installed in tanks carrying gasoline, diesel, aviation fuel, fuel oil
#4. While coefficients of expansions specific to RHD have not been determined, the temperature
correction factors currently in use are functions of both the product density and the temperatures.
Because ATGM is widely used and tested with various fuels of varying densities, ATGM should cover
diesel fuel containing up to 100% of NEXBTL.
Bulk Underground Storage Tank Leak Detection Method (50,000 Gallons or Greater), (BUSTLDM):
There are about nine manufacturers of BUSTLDM. They use various technologies such as mass
balance, ATG or other technology to detect leak in the mostly single large tanks. These systems are used
for variety of fuel such as: gasoline, diesel, aviation fuel, fuel oil #4, fuel oil #6 (if is between 60 to 150
degrees F), solvents, waste oil, liquefied petroleum gas, and natural gas. Since BUSTLDM are capable of
storing such a varied group of fuels, they are capable of storing and handling diesel fuel containing up to
100% of NEXBTL in a single tank.
Continuous In-Tank Leak Detection Method (Continual Reconciliation) (CITLDM):
Technologies that use CITLDM are very similar to ATGs, and, therefore, the impact of NEXBTL on
them will be the same as those of ATGs. Therefore, the ability of CITLDM is such that it easily can
manage NEXBTL fuel up to 100%.
Continuous Interstitial Monitoring Method (Liquid Filled) (CIMM):
There are about four manufacturers of CIMM. These technologies are applied for testing the
leaks on pipes and tanks. These methods should work for RHD containing up to 100% of NEXBTL. The
space between the two tank layers ( or the pipe layers) of the tank is continuously monitored and alarm
will go off if the level goes down when a leak is developing, or if it goes up meaning that fuel is intruding
into the interstitial space. Because RHD consists mainly of iso and normal paraffins and essentially no
aromatics and diesel fuel can contain up to 35% aromatics with the balance consisting mainly of iso,
normal and cyclo paraffins (C3H6) the liquid that fills interstitial space may need to be tested for
compatibility with ultra low sulfur, low aromatics content fuels. If the leak goes into the product a high
sulfur content of low flash point interstitial fluid can cause both ULSD and RHD to go off specification. If
the leak goes from the tank to the interstitial fluid the relatively low toxicity of the paraffinic RHD should
be less of a problem than a ULSD leak containing aromatics.
30
Continuous Interstitial Line Monitoring Method (Pressure/Vacuum) (CILMM):
There are not very many manufacturers of these systems and since these system use
pressurized nitrogen gas to continuously maintain a pressure in the interstitial space of the pipelines,
they should be accepted and used for pipelines carrying NEXBTL up to N100.
Continuous Interstitial Tank System Monitoring Method (Pressure/Vacuum), (CITSMM):
There are about eight manufacturer of CITSMM. These systems use an integral vacuum pump to
continuously maintain a partial vacuum within the interstitial space of double-walled tanks and doublewalled piping. Since these systems are double-walled and they are under vacuum/pressure they should
be able to manage RHD up to 100%.
Continuous Pressurized Piping Leak Detection Method (Continuous Electronic Line Leak Detection)
(CPPLDM):
There is only one manufacture building CPPLDM. This system only reports passes or fails and its
use are not wide spread. According to it manufacturer the system is capable of storing Gasoline, diesel,
aviation fuel, biodiesel B6-B20 meeting ASTM D7467, biodiesel B100 meeting ASTM D6751. Since the
system operates on pressure and NEXBTL follows the Pascal’s laws, it can handle up to 100% RHD.
Interstitial Detector (Liquid-Phase) ID:
The installation of Interstitial Detector is wide spread and more than twenty five manufacturers
build this device and some are slightly different from the others with different liquid filled in the
interstitial space. The alarm is activated when the product gets into the interstitial space. The
manufacturer of Interstitial Space claims that Biodiesel blends B6-B20 meeting ASTM D7467 and
biodiesel B100 meeting ASTM D6751 would also produce an alarm if the sensor threshold is exceeded.
The alarm is also activated when gasoline, diesel or water entering in the interstitial space. With the
approval of the manufacturers those same detectors that work with B100 can work with RHD up to
N100.
Interstitial Tank Tightness Test Method (ITTTM):
There are three manufacturers of these ITTTM systems. Their technologies are based on either
vacuum or liquid to fill the interstitial space. According to their manufacturers these systems are capable
of handling gasoline, diesel, aviation fuel, fuel oil #4, motor oil, biodiesel blends B6-B20 meeting ASTM
D7467, biodiesel B100 meeting ASTM D6751. Since these technologies don’t come in contact with the
product in the tank and they are approved for B100, they are capable of managing RHD up to N100.
31
Large Diameter Line Leak Detection Method (6 Inches Diameter or Higher) (LDLLDM):
There are about ten producers of these systems. According to their websites there are two
distinct methods for detecting leaks. One is based on either pressure or vacuum; these systems should
work with RHD.
The other method is the “tracer”, or addition of special kind of chemical to the product in the
pipeline. If the added tracer doesn’t dissolve in paraffins, then the tracer method will not work for neat
RHD. If the tracer is dissolvable in traditional diesel fuel because traditional diesel fuel contains
aromatics then, given the trend to lower aromatics content in cleaner burning diesel fuels, the tracer
manufacturer should determine the minimum aromatics content at which the tracer dissolves and
establish application guidance concerning the use of the tracer technology when paraffinic distillate
fuels like RHD and Fischer-Tropsch fuels are present. Assuming the tracer works in cleaner burning
diesel fuels like CARB ULSD and TxLED that encourage the use of diesel fuels containing less than 10%
aromatics equivalent performance and that typical diesel fuel contains between 20 and 25% aromatics.
Pipelines that rely on “tracer” that is not dissolvable in NEXBTL, can still manage blends of up to N50 or
N60 of RHD. If the tracer chemical is soluble in paraffins the method should work for neat RHD.
Line Tightness Test Methods (LTTM):
There are about fifteen manufacturer of LTTM. The tightness of some these systems are tested
by putting the pipeline under pressure. These systems should be acceptable for RHD.
The other method for testing LTTM is by adding “tracers” in the pipeline. If the added tracer
doesn’t dissolve in RDH, then the tracer method will not work for neat RHD. If the tracer is soluble in
traditional diesel fuel because traditional diesel fuel contains aromatics then, given the trend to lower
aromatics content in cleaner burning diesel fuels, the tracer manufacturer should determine the
minimum aromatics content at which the tracer dissolves and establish application guidance concerning
the use of the tracer technology when paraffinic distillate fuels like RHD and Fischer-Tropsch fuels are
present. Assuming the tracer works in cleaner burning diesel fuels like CARB ULSD and TxLED that
encourage the use of diesel fuels containing less than 10% aromatics equivalent performance and that
typical diesel fuel contains between 20 and 25% aromatics. Pipelines that rely on “tracer” that is not
dissolvable in NEXBTL, can still manage blends of up to N50 or N60 of RHD. If the tracer is soluble in
paraffins the method should work for neat RHD
Non-Volumetric Tank Tightness Test Method (Tracer) (NVTTTMT):
There are three manufacturers of NVTTTMT. These are non-volumetric methods. Chemical
tracers are added to the tank to check and see if the residue of the tracers is found in the ground around
the tank. If the tracer used is not dissolvable in RHD, then the tracer method will not work for neat RHD.
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If the tracer is soluble in traditional diesel fuel because traditional diesel fuel contains aromatics then,
given the trend to lower aromatics content in cleaner burning diesel fuels, the tracer manufacturer
should determine the minimum aromatics content at which the tracer dissolves and establish
application guidance concerning the use of the tracer technology when paraffinic distillate fuels like RHD
and Fischer-Tropsch fuels are present. Assuming the tracer works in cleaner burning diesel fuels like
CARB ULSD and TxLED that encourage the use of diesel fuels containing less than 10% aromatics
equivalent performance and that typical diesel fuel contains between 20 and 25% aromatics. Tanks that
rely on “tracer” that is not soluble in NEXBTL, can still manage blends of up to N50 or N60 of RHD. If the
tracer is soluble in paraffins, there does not appear to be a reason it would not work with neat RHD.
Non-Volumetric Tank Tightness Test Method (Ullage) (NVTTTMU):
There are seven manufacturers of NVTTTMU. These systems work on either pressure or vacuum
in the ullage part of the tank and, therefore, the system is not in contact with the product in the tank.
Since the RHD doesn’t come in contact with the product and methods works with several different
petroleum products, it should handle RHD.
Non-Volumetric Tank Tightness Test Method (Vacuum) (NVTTTMV):
There are six manufacturers of NVTTTMV. These systems do not come in contact with the
product and, therefore, they work with any kind of product including RHD.
Out-Of-Tank Product Detector (Liquid-Phase) (OOTPDLP):
There are seventeen manufacturers of OOTPDLP. As the name suggests these detectors are
placed out of the tank and detect hydrocarbons and the presence of a wide range of petroleum fuels,
e.g. gasoline, diesel, jet fuel, etc. In some cases the detector which is a special kind of wire may be
reused after detecting petroleum fuel and hydrocarbons. If the detector is only sensitive to aromatic
hydrocarbons RHD blends in the 50 to 60% range should be acceptable as long as the system works for
cleaner burning diesel fuels like CARB ULSD and TxLED. As long as the detector is sensitive to
hydrocarbons it should work for neat RHD.
Out-Of-Tank Product Detector (Vapor-Phase) (OOTPDVP):
There are sixteen manufacturers of OOTPDVP. These detectors are usually placed (in a well)
near a tank to detect hydrocarbons. They generally work with fuels that have a high partial evaporation
and are volatile. That is because the molecules quickly change from liquid to vapor and move about and
reach the detector very quickly. Those fuels that are relatively more stable compared to alcohol and
gasoline such as kerosene, diesel, and RHD are not suitable for these detectors.
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Statistical Inventory Reconciliation Test Method (Qualitative) (SIRTMQ):
There are not many vendors performing SIRTMQ on the customer’s tanks. SIRTMQ method
reports pass or fail only. Probes and sometimes sticks are used to measure the product level. The probes
should be fine for most hydrocarbon products and should work for neat RHD. A possible exception to
this conclusion can occur when the probes rely on the presence of aromatics or some other contaminant
to function. Probes makers should be contacted to see if probes are compatible with today’s cleaner
diesel fuels and paraffinic fuels like RHD and Fischer-Tropsch fuels.
Statistical Inventory Reconciliation Test Method (Quantitative) (SIRTMQ):
There are about fifteen vendors selling SIR/Quantitative. Some vendors manufacture their own
probes. Assuming the probes work for hydrocarbons the SIR/Quantitative method should be fine for
RHD. Should the probes rely upon the presence of aromatics or some other contaminant to function the
probe makers should be contacted to see if their probes are compatible with today’s cleaner burning
diesel fuels and paraffinic fuels like RHD and Fischer-Tropsch fuels.
Volumetric Tank Tightness Test Method (Overfill), (VTTTMO):
There are about eight companies involved in VTTTMO. Their method is volumetric and tests the
filled portion of the tank for leak. Assuming these methods are valid for hydrocarbons the methods
should be accepted for RHD.
Volumetric Tank Tightness Test Method (Underfill), (VTTTMU):
There are about nine companies involved in VTTTMU. Some measure the mass instead of
volume. They generally test the filled portion of the tank. Assuming these methods are valid for
hydrocarbons they should be acceptable for RHD.
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Concluding Remarks:
The second part of this report investigates the impact of the RHD on tanks and the special
equipment placed inside or outside of a tank. Most leak detection methods are conducive to renewable
hydrocarbon diesel. For a few that are not the manufacturer of the product should be consulted. They
may have a recommendation or even a substitute for that particular method that works with RHD. Since
RHD is stable, has a low affinity for water and is essentially free of water, oxygen, alcohol and other
contaminants known to cause corrosion, there is no technical reason that neat RHD cannot be stored in
or dispensed from underground storage tanks or above ground storage tanks that are suitable for use
with diesel fuel.
While no direct test data has been found that indicates that RHD is or is not compatible with
leak detection equipment, pipelines and storage tanks RHD has been distributed commercially since
2007 in concentrations ranging from less than 5% to up to 100% and no leaks or equipment failures have
been attributed to its presence. Also, there is a vast amount of references supporting the production
and the use of RHD. Some of these references have been mentioned in the first part of this paper and
they include governmental agencies, non-profitable organizations, universities, etc. For example:
California’s multimedia evaluation indicates that renewable diesel is chemically comparable to CARB
diesel. Therefore, differences in compatibility and leak detection are not anticipated.
While we would like to see some gravity-temperature correction factors that are specific to
RHD, the typical gravity-temperature correction factors that are a function of the gravity of the fuel
being measured and the temperature difference are probably adequate.
One possible soft spot may be leak detection equipment or procedures that rely upon chemical
tracers that that have to be dissolved in the diesel fuel. Leak detection vendors that rely on chemical
tracers should verify that their tracers are soluble in paraffins and continue to work as aromatics
content of diesel fuel is reduced to make it burn more cleanly.
Because RHD is diesel fuel that emits very few volatile vapors relative to gasoline or
alcohol, vapor emissions sensors that do not work with diesel fuel will not work with RHD either
While my research has not found any technical reasons as to why RHD is not compatible with
the existing leak detection and fuel transport and containment facilities it would still be prudent to be
extra vigilant when handling diesel fuels containing high concentrations of RHD simply because it is still a
relatively new fuel.
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References
Below are some related URLs. A few have been mentioned in the text and others although not
mentioned in the text contain useful information:
http://www.nwglde.org/method_index.html
http://www.veeder.com/us/fuel-leak-detection/mechanical-line-leak-detection/fxv-mechanical-lineleak-detector
Mass measurement EPA
http://www.epa.gov/esd/chemistry/ice/ac1.htm
http://www.arb.ca.gov/fuels/multimedia/meetings/RenewableDieselStaffReport_Nov2013.pdf
http://www.arb.ca.gov/fuels/multimedia/meetings/BiodieselStaffReport_Nov2013.pdf
http://www.egreenee.com/wp-content/uploads/2013/09/Doc-7NRELTestSummaryReportFeb2012they-belong-to-FED.pdf
http://www.arb.ca.gov/fuels/diesel/altdiesel/20130212adfregconcept.pdf
http://www.vtt.fi/inf/julkaisut/muut/2008/VTT-R-07049-08_GB.pdf
http://www.equipmentworld.com/
Under the heading “ADVANCED ALTERNATIVE AND RENEWABLE DIESEL FUELS” there are a few good
references.
http://www.nrel.gov/docs/fy06osti/38834.pdf
http://www.chevronwithtechron.ca/products/documents/Diesel_Fuel_Tech_Review.pdf
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