TECHNICAL

Biodiesel is produced by the reaction of a vegetable oil or animal fat with an alcohol (typically methanol) in the presence of a catalyst to yield mono-alkyl esters (biodiesel or methyl ester) and glycerin (~10% by weight). This reaction is called transesterification. Raw or refined vegetable oil or recycled greases that have not been processed into biodiesel are not biodiesel.

One of biodiesel’s advantages is that it can be used in unmodified diesel engines and with little or no change to fuelling infrastructure. Biodiesel has a higher cetane number than most diesel fuel, allowing it to provide similar fuel consumption, horsepower, torque, and haulage rates as fossil diesel fuel. Hundreds of millions of on-road kilometers and countless marine and off-road applications as well as extensive studies have demonstrated biodiesel’s power and efficiency across the full range of duty cycles and applications.

Numerous tests of biodiesel and petroleum diesel show the distinct improvement in lubricity when biodiesel is added to conventional diesel fuel, above the additized level in all commercially available diesel. Ultra Low Sulphur Diesel has poor lubricity, and is heavily additized with lubricity conditioners. Biodiesel blends as low as one percent can provide up to a 65 percent increase in lubricity in distillate fuels and help prevent premature engine component deterioration. The increased lubricity of biodiesel is associated with a noticeable decrease in engine noise in some applications.

Blends of up to B20 have been widely shown to be compatible with all diesel engines in high-blend states such as Minnesota, Illinois and Iowa. Biodiesel contact with natural or butyl rubber components (primarily fuel hoses and pump seals) is not recommended in excess of B20 blends in engines older than 2004. Certain elastomers soften and degrade with prolonged exposure to higher levels of biodiesel.

Refinery diesel and biodiesel are both amended at the wholesale rack to create fit-for-purpose fuels. Diesel fuels are additized, and biodiesel is additized and blended into diesel to provide predictable performance. Like regular diesel fuel, biodiesel blends can gel at very low temperatures. The composition and cold flow properties of diesel fuels vary widely across Canada. Low levels of biodiesel can be accommodated in any diesel fuel in Canada. The biodiesel content will depend on factors such as the time of year, location, diesel and biodiesel properties (including cloud point).

The cold flow properties of B20 or higher biodiesel blends can vary appreciably based on the feedstock from which they are made. In general, the better the cold flow characteristics of the base diesel fuel, the greater the effect of blending biodiesel on its cold flow properties. Mid-level (up to 20%) blends can be used seasonally in most parts of Canada.

Diesel and biodiesel blends are both placed into the market with ‘fit for use’ assumptions that anticipate probable use, including delays between purchase and use and travel by the fuel user to a colder region.

Additizing biodiesel blends to achieve expanded cold flow performance is a common practice in northern US states; Minnesota fleets blend 5% biodiesel into winter diesel in part through additization. A 2011 third-party documented demonstration of B10 blends in a large longhaul trucking fleet showed that biodiesel is a robust fuel. Biodiesel vehicles parked outside cold-started when straight diesel did not, and 10% blends with no additization or kerosene were employed through the full temperature range of an Alberta winter. Another Alberta study in 2009 showed that a B2 blend was fully compatible with an Alberta winter, performing well beyond the projected operability limit.

All major Original Equipment Manufacturers (OEM) approve the use of up to 5% biodiesel (B5) when blended with diesel fuel that meets the appropriate CGSB and ASTM standards. BQ9000 accreditation is specified by some OEMs. Cummins has approved all of its engines for 7% biodiesel blends.

Millions of diesel vehicles run mid-level blends (B6-B20) every day with full operability and billions of successful US and Canadian road miles over two decades. Engine manufacturers are full participants in developing the strict biodiesel quality standards that enable the use of blends up to 20% (B20). OEMs have been party to widespread commercial use of B11, B15 and B20 in several US states (e.g., Illinois, Minnesota) and neither they nor other stakeholders have reported any more incidence of engine or operability issues than is found with straight diesel.

Truck manufacturers have not intervened in markets to disapprove regulations and incentives for mid-level blends. Strong fuel quality oversight, and an experienced petroleum sector, has been important to mid- level blend success, including BQ9000 fuel quality accreditation and the adoption of inline biofuel blending capabilities.

OEMs express warranty approval only for models that have been tested on biodiesel blends; this is common for late-model engines. When an OEM does not express biodiesel approval for an engine, it means only that biodiesel testing has not been conducted on that engine. Manufacturers mostly do not test legacy models; they are ‘out the door’, with biodiesel testing conducted only on new models.

Lack of warranty approval is sometimes mistakenly taken to mean that an engine will not be operable above the warranted blend level or that warranties will be voided for use above the stated level. This is not accurate. Where an affirmative warranty statement has not been given, the OEM has not specifically tested that model.

A joint statement by the Oregon Auto Dealers Association and the Northwest Biofuels Association explains the Magnuson-Moss Warranty Act (MMWA) for biodiesel in the simplest terms:

“A vehicle’s warranty cannot be voided solely due to the use of biodiesel. Even if the manufacturer recommends a blend of 5% biodiesel and a customer uses a higher blend such as 20% or 99% biodiesel, this does not void the warranty. If a customer uses a blend of biodiesel that is not recommended, that in and of itself, does not void the warranty. If the biodiesel is not the cause of the engine or parts failure, the warranty must be honored (assuming the failure is not the result of another external factor).”

The term ‘blend wall’ is sometimes used to claim that a 5% biodiesel blend is the level above which engine manufacturers will not honor for their warranty”.

Warranty positions by engine manufacturers have not prevented the petroleum industry from distributing very large volumes of mid-level B6, B7, B11, B15 blends (up to B20, B50 and B99) in markets far larger than Canada. US major oil companies widely market blends >5%. There is no impediment to such mid-level blending in Canada.

(See Warranties) Hundreds of millions of miles of on-road heavy-duty fleets history in the US alone shows no adverse engine impact. One US fleet alone reported in 2010 that, “Its vehicles have accumulated more than 60 million miles using B20 without encountering biodiesel-related issues, and evaluations have demonstrated no appreciable change in fuel economy, engine wear, or driver acceptance.” And a report of 26 months of data collection on 10 commercial HD trucks running B20 for 2,035,968 miles, matched with a control group on ULSD, was supported with engine teardown analyses that “did not reveal any notable differences between the two groups.”

To quality for eligibility in renewable fuel regulations in all four western provinces, commercially available biodiesel must meet strict CGSB (Canadian General Standards Board) specifications. Updated standards were published in 2012 for B1-5, B6-20, and B100 to ensure that biodiesel produced to these standards will ensure full operability in modern diesel engines.

The US and European Union have ASTM and EN standards respectively.

U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) found that 95% of the samples from 2011-12 met ASTM International fuel quality specifications.

Used cooking oils that are non-transesterified are not biodiesel. Higher viscosities, and impurities in these unprocessed fuels, are associated with problems that may include piston ring sticking, fuel system deposits, reduced power, shorter engine life, lower fuel economy, increased exhaust emissions, plugged fuel filters and higher injection pressures. Based on these issues, ABFC has not supported the commercial application of non-CGSB or non-ASTM fuels.

The CGSB biodiesel standards (e.g., CAN/CGSB-3.520-2011 for B1-5) contain appendix guidelines for biodiesel handling and blending of biodiesel. Other sources of handling and use guidelines can be found in the Resources section.
In general, good fuel management practices for diesel fuel will ensure trouble-free use of biodiesel when blended.

  • Storage: cool, clean, dry conditions, with free water drained from storage tanks and filter housings.
  • Desiccant filters may be appropriate for above-ground storage of neat or higher-level blends.
  • Stability additives may be helpful for long-term storage of biodiesel.
  • A guideline of maximum six month’s storage is recommended; however, oxidation stability additives can extend that period significantly. US Department of Energy tests show additized biodiesel blends remained on-specification for three years.
  • To prevent precipitation of trace components from some biodiesels, biodiesel and diesel fuel should be at least 5°C above their respective cloud points when they are blended.

Biodiesel blending using inline or injection blending provides the greatest assurance that a consistent blend has been achieved. Sequential or ‘batch’ blending as an alternative where inline blending is not available/feasible is used successfully in a wide range of conditions in Canada and the US. For proper splash blending techniques, refer to Biodiesel Handling and Use Guide (5th edition, November 2016 —DOE National Renewable Energy Laboratory.)

What is Ethanol?

Ethanol is ethyl alcohol and is a product of biochemical or thermochemical processes. Advanced cellulosic ethanol is made from sorted municipal solid waste and from agricultural and forestry residues. Ethanol has the same chemical formula regardless of whether it is produced from starch- and sugar-based feedstocks, such as corn or wheat grain (as it primarily is in North America), sugar cane (as it primarily is in Brazil), or from cellulosic feedstocks.
Ethanol has a higher octane number than gasoline, providing premium blending properties. Minimum octane number requirements prevent engine knocking and ensure drivability. Low-octane gasoline is blended with 10% ethanol to attain the standard 87 octane requirement. Ethanol is the main component in mid- and high-level ethanol blends. (AFDC)

E15 Blend Compatibility

Flex-fuel vehicles are compatible with E15 and in October 2010, the U.S. Environmental Protection Agency (EPA) approved a waiver concerning gasoline additives that permitted the use of E15 in model year 2007 and newer autos and light duty motor vehicles. In January 2011, the EPA extended the waiver to permit the use of E15 in 2001 to 2006 model year passenger cars, light duty trucks, and medium-duty vehicles.

Energy Content and Mileage

Ethanol contains less energy per gallon than gasoline. Pure ethanol contains about 30% less energy than gasoline.

E10 — Much of the gasoline in Canada contains 10% ethanol. Any vehicles can use E10 and will typically experience a 3% to 4% fuel economy reduction when using E10.

E15 — There is no Canadian standard for 15% blends of ethanol in gasoline, and as a result it is not retailed in Canada. In the US after 2011, the EPA began allowing the use of E15 in model year 2001 and newer gasoline vehicles. Pumps dispensing E15 must be labeled.

Vehicles will typically have 4% to 5% lower fuel efficiency on E15 than on 100% gasoline.

E85 — E85 fuel contains between 50% and 83% ethanol. Flex Fuel Vehicles (FFV) operating on E85 get roughly 15% to 30% fewer miles per gallon, depending on ethanol content, than when operating on regular unleaded gasoline. In the US, E30 blends suitable for FFV are also marketed.

Standards & Quality

CAN/CGSB-3.511-2011 Oxygenated Automotive Gasoline Containing Ethanol (E1-E10). This standard applies to four grades of oxygenated gasoline to which no lead or phosphorus compounds have been added, and in which the oxygenate consists essentially of ethanol. They are intended for use in spark ignition engines under a wide range of climatic conditions.

CAN/CGSB-3.512-2013, Automotive ethanol fuel (E50-E85). This standard has been specifically developed to help ensure acceptable vehicle operability in Canada’s cold winters. It applies to automotive fuel composed of 50 to 85% by volume denatured fuel ethanol and gasoline strictly for use in flexible fuel vehicles over a wide range of climatic conditions.

What is Renewable Hydrocarbon Diesel

Renewable hydrocarbon diesel (RHD) is also known as Hydrogenation-derived renewable diesel (HDRD), hydrogenated vegetable oil (HVO), Green Diesel (EU), and renewable diesel (US). It is the product of fats or vegetable oils—alone or blended with petroleum—refined by a hydrotreating process. RHD meets petroleum diesel CGSB and ASTM specifications. (AFDC)

RHD can be produced from vegetable oil; animal tallow; cooking oil residues; and other fats and vegetable oils. Producing RHD involves hydrogenating triglycerides to remove metals and compounds with oxygen and nitrogen using existing refinery infrastructure. Dedicated hydrotreating facilities that do not use conventional petroleum can also produce RHD.

RHD can be substituted for or blended in varying proportions with petroleum-based diesel without modifying vehicle engines or fueling infrastructure. As a result of minor difference in properties from conventional diesel, RHD blending levels to 20-30% have been the norm in Canada. RHD refining can produce biofuel of varying low temperature operability.

Renewable natural gas (RNG) is defined as methane gas derived from organic materials and waste streams. Pipeline–grade RNG has been upgraded (also called conditioning) to remove water, carbon dioxide, hydrogen sulfide, and other trace elements. This meets natural gas pipeline specifications, and also meets those set for natural gas vehicles by engine manufacturers.

Like conventional natural gas, RNG can be used as a transportation fuel in the form of compressed natural gas (CNG) or liquefied natural gas (LNG). RNG qualifies as an advanced biofuel under the US Renewable Fuel Standard.

The primary “feedstocks” for producing RNG are:

1. Agricultural and agri-food sources such as unused crop residues, animal manure and food processing waste;
2. Forestry bi-products such as wood waste generated during harvest operations;
3. Municipal solid waste and bio-solids from wastewater.

RNG can be produced using either anaerobic digestion, an established technology best suited for producing RNG from relatively wet feedstock or gasification, which is a rapidly developing technology best suited for producing RNG from relatively dry feedstock.

Anaerobic digestion (AD) is a natural process of decomposition of organic materials by microbes in the absence of oxygen, in which biogas is produced. Anaerobic digestion occurs in landfills and sewage treatment and in industrial processes to convert manures, agri-food residues, industrial by-products and sorted municipal wastes to biogas.

The resulting biogas contains a much lower methane concentration than conventional natural gas and can be used on-site with minor processing for its heating value or to run an electricity generator. However, upgrading technologies are available that can produce a clean, high energy RNG suitable for direct injection into existing natural gas pipeline infrastructure and able to be mixed with conventional natural gas.

Biomass gasification is a high temperature (>500 °C) process in which organic material is converted into syngas in the presence of oxygen and/or steam. The syngas can be converted into RNG through a process called methanation and then be introduced into the natural gas pipeline infrastructure and mixed with conventional natural gas.

Gasification has the advantages over anaerobic digestion that a wider variety of non-homogeneous feedstocks can be utilized. Almost any type of organic material can be used as gasification feedstock, including forestry and agriculture residues, and sorted municipal waste.

The extensive Canadian pipeline and underground gas storage network and the interchangeability of RNG with conventional natural gas means that in many cases, RNG can be introduced at its point of production, and transported and transported to the end user without a significant modification to pipeline infrastructure or to the end user’s natural gas burning equipment.

Sources: CANMET Technology Roadmap / AFDC

Biocrude is a concentrated, synthetic bio-oil substitute for petroleum crude oil, which is produced using thermochemical conversion of a wide range of biomass (forestry residues, crop residues, waste paper and organic waste). It is compatible with existing refinery technology when pretreated and co-processed with crude oil at low levels for conversion into renewable gasoline and diesel.

Biocrude has also been used for decades as a low carbon fuel for heating and cooling suitable for use in existing conventional commercial and industrial grade boilers by utilities and institutional users.

Refinery co-processing of bio-oils provides refiners with an option to utilize existing refining assets to produce low carbon fuels. Biocrude has been demonstrated in Canada, Europe, the US and South America.

Pyrolysis and Hydrothermal liquefaction

Biocrude is produced by pyrolysis or hydrothermal liquefaction.

PYROLYSIS – The pyrolysis process uses thermal decomposition occurring in the absence of oxygen. It is the first step in combustion and gasification processes where it is followed by total or partial oxidation of the primary products. Lower process temperature and longer vapour residence times favour the production of charcoal. High temperature and longer residence time increase the biomass conversion to gas and moderate temperature and short vapour residence time are optimum for producing liquids.

Typical product yields (dry wood basis) obtained by different modes of pyrolysis of wood:

Mode Conditions          Wt% Liquid Char Gas
Fast ~500oC, short hot vapour residence time ~1 s 75% 12% 13%
Intermediate ~500oC, hot vapour residence time ~10-30 s 50% 25% 25%
Slow – Torrefaction ~290oC, solids residence time ~30 mins 82% solid 18%
Slow – Carbonisation ~400oC, long vapour residence time hrs -> days 30% 35% 35%
Gasification ~800oC 5% 10% 85%

In fast pyrolysis biomass decomposes to generate mostly vapours and aerosols and some charcoal. After cooling and condensation, a dark brown mobile liquid is formed which has a heating value about half that of conventional fuel oil. While it is related to the traditional pyrolysis processes for making charcoal, fast pyrolysis is an advanced process, with carefully controlled parameters to give high yields of liquid.

The essential features of a fast pyrolysis process for producing liquids are:
• Very high heating and heat transfer rates at the reaction interface, which usually requires a finely ground biomass feed;
• Carefully controlled pyrolysis reaction temperature of around 500oC and vapour phase temperature of 400-450oC;
• Short vapour residence times of typically less than 2 seconds;
• Rapid cooling of the pyrolysis vapours to give the bio-oil product.

Virtually any form of biomass can be considered for fast pyrolysis. While most work has been carried out on wood due to its consistency, and comparability between tests, nearly 100 different biomass types have been tested by many laboratories ranging from agricultural wastes such as straw, olive pits and nut shells to energy crops such as miscanthus and sorghum, forestry wastes such as bark and solid wastes such as sewage sludge and leather wastes.

Source:IEA Task 34

HYDROTHERMAL LIQUEFACTION — Biocrude can also be produced using another thermochemical conversion process, hydrothermal liquefaction (HTL), which is the thermal depolymerization of wet biomass under moderate temperature and high pressure. These conditions, over period of minutes, mimic geologic processes that have converted biogenic materials into carbonaceous energy in the earth’s crust over millennia. HTL produces a liquid oil directly, whereas pyrolysis produces a syngas which is converted into liquid oil in the presence of a catalyst.

Biomass feedstocks for HTL include biowaste (manure and food processing waste), industrial processes wastes (e.g. wastewater treatment sludge), lignocellulose (crop residue), and algae.

AJF is a synthetic kerosene (aviation jet fuel) derived from a range of biomass such as vegetable oils and animal fats, forest or agricultural resides, and industrial waste gases. Bio-based aviation fuels must be produced using ASTM-approved technology pathways, so that the AJF can be used in existing jet engines without modifications for their use.

Aside from important efficiency improvements, biofuels provide the only feasible medium term option for the aviation sector to improve its carbon footprint as the aviation sector is likely limited to liquid fuels for the coming decades.

Currently no manufacturer of aircraft or engines intends to restrict the use of their equipment to a particular fuel or way of operating that is markedly different from the aviation fuels currently in place. As a result, short to medium term alternative aviation fuels must be “drop in” replacement of fossil kerosene as the development of new engines, aircraft and infrastructure is complex and expensive. New types of aircraft (with corresponding engines) that could employ “non-drop in” fuels could enter the market in the future, but are not likely to occur at commercial scale before 2050 due to the slow replacement rates of current aircraft.

Biojet is produced using a combination of biochemical and thermochemical processes.

The vast majority of biojet commercially available today uses hydrotreatment of esters and fatty acids (HEFA), which converts oleochemicals to jet via deoxygenation with hydrogen and cracking.

Other technology pathways also have approved ASTM biojet registrations:

  • Fischer-Tropsch (FT) converts carbon-rich material (e.g. biomass) into sugars, which are then catalytically converted to jet fuel.
  • Alcohol to Jet (ATJ) converts sugar/ starch derived alcohols to jet via dehydration, oligomerization and hydrogenation. Alcohol feedstocks include biomass, MSW, and industrial waste gases.
  • Direct Sugars to Hydro Carbons (DSHC) ferments plant sugars and starches to hydrocarbons which are subsequently thermo-chemically upgraded to jet fuel.

ICAO (International Civil Aviation Organization) has a web tool that provides real time data on flights (in progress) that are using alternative jet fuel: https://planefinder.net/custom/icao-fuel.php