What are biofuels?
Biofuels is a generic term for fuels that can be produced from or are made up of a renewable material of plant or animal origin. Often they are substitutes or partial substitutes for fossil or mineral fuels. Biofuels used in transport are typically bioethanol which is used as a petrol substitute and biodiesel which is used as a diesel substitute. Biodiesel can also be used in residential and industrial space heating.
Biofuels have the major advantage of not contributing to overall greenhouse gas emissions.
What is biodiesel?
Biodiesel can be produced from any vegetable oil or animal fat and used as a substitute or partial substitute for mineral diesel. To produce biodiesel, these fats or oils are chemically converted to esters that have properties similar to mineral diesel. Biodiesel is often blended with mineral diesel and blends of up to 5 % in mineral diesel are suitable for use in diesel engines without modification. Higher blends may be used in dedicated fleets.
In New Zealand, biodiesel is produced from tallow and rape seed (Canola). On a smaller scale, some biodiesel is being produced from Jatropha plants and Algae. Biodiesel can also be made from used cooking oils and fats (fuel used directly is not biodiesel).
What is bioethanol?
Bioethanol is an alcohol made from sugar, starch and products containing sugars and starches, through a process of fermentation and distilling, and used as a substitute or partial substitute for petrol. Bioethanol has properties that are similar to petrol so it is often blended with petrol. Bioethanol has been introduced as a low level blend i.e 3% to 5% and 10% in some petrol, the current maximum level allowed is 10%. Higher blends may be used in dedicated fleets.
In New Zealand, bioethanol is being produced from whey. Other options include cellulosic materials like waste wood, and straw and even food waste.
How are they made?
What is the difference between first and second generation biofuels?
First generation biofuels are produced from sugars, starches, vegetable oils or animal fats from proven technology. Examples include biodiesel from tallow and bioethanol from whey.
Second generation biofuels generally refer to new methods of producing biofuels. They are not yet ready for commercial development but are the subject of extensive research and development internationally. Research is also active in New Zealand on Second Generation Biofuels (see here for more details). Examples include the conversion of plant lignin and cellulose into fuels by enzymes and the gasification of biomass material followed by a “gas to liquid” Fischer-Tropsch process. Biomass that could be used in this process include all types of trees, grasses, agricultural plant wastes, straw and algae.
Benefits of biodiesel and bioethanol
Biodiesel has a number of other advantages over ordinary diesel:
- Readily broken down by bacteria. Even small amounts of biodiesel mixed with diesel will speed up the breakdown of fuel spills.
- Much higher flash (ignition) point than mineral diesel, making it safer to transport.
- Lower emissions, reduced ozone forming potential, almost no sulphur, and reduced production of carcinogens.
- Better engine lubricating properties resulting in reduced engine noise.
- Growing crops for biodiesel production can mean that otherwise poorly positioned or infertile soils can become profitable for their owners. The crops can often improve the quality of the soil. Environmental groups criticise the destruction of forests and land that would otherwise be used for growing edible crops to then grow biofuel crops and rightly so. Growing biofuels does not have to be at the expense of food crops. Sustainably produced biofuels offer a solution. This ‘food vs fuel’ debate has gathered momentum in the last few years. It is important to buy biofuels from sustainable sources. Much work is going on internationally to define the Sustainability Criteria for Biofuels. See the LBIG view on ‘food vs fuel’ here.
Bioethanol has a number of advantages over petrol:
- The main advantage of bioethanol over petrol is its renewability and carbon neutrality. It is renewable energy source because it is produced from plants that are grown and harvested every year.
- Bioethanol is meant to be historically the fuel of choice with the fist internal combustion engine designed to run on ethanol. Their octane rating is 113 in comparison with the petrol ones whose octane rating is between 83 and 95. The higher the octane rating is the less “knocking” will be heard – pre-ignition of the fuel, which damages engines.
- Another advantage is the independence which bioethanol may give different countries. Currently reliant in imported carbon-based fuels.
- Growing crops for bioethanol production can mean that otherwise poorly positioned or infertile soils can become profitable for their owners. The crops can often improve the quality of the soil. Environmental groups criticise the destruction of forests and land that would otherwise be used for growing edible crops to then grow biofuel crops and rightly so. Growing biofuels does not have to be at the expense of food crops. Sustainably produced biofuels offer a solution. This ‘food vs fuel’ debate has gathered momentum in the last few years. It is important to buy biofuels from sustainable sources. Much work is going on internationally to define the Sustainability Criteria for Biofuels. See the LBIG view on ‘food vs fuel’ here.
Ethanol and Biodiesel Blends
E5 - is an ethanol blend fuel which consists of 5% ethanol of 95% petol.
E10 - is an ethanol blend fuel which consists of 10% ethanol and 90% petrol.
E85 - is an 85% ethanol blend with 15% petrol. In March 2009 the Environmental Risk Management Authority (ERMA) approved an application from EECA to allow E85 with controls.
More details on the ERMA decision to approve the application can be found here.
E100 - Neat ethanol can be used as a fuel, although vehicles must be specifically designed for this purpose. Vehicles suitable for operating on neat ethanol are not currently available in the New Zealand market. It is therefore not considered necessary at this time to introduce a regulated specification for hydrous or anhydrous ethanol to be used as fuel in neat form (i.e. unblended).
B5 - is a blend of 5% biodiesel and 95% mineral diesel. In March 2009 Mobil announced its plans to trial the sale of B5 in the Bay of Plenty - Questions and Answers here.
B20 - is a blend of 20% biodiesel and 80% mineral diesel
B100 - is 100% pure biodiesel
Biofuels Technical Terms
Batch Processing - Since the 1940s, batch processing (one quantity of raw material at a time) has been used, with separation of biodiesel from glycerol being the final part of the process. The advantages of batch operation are given as cheap cost and flexibility to accommodate changes in raw materials quality and quantity. The disadvantages are difficulty in attaining consistency of product quality and safety.
Cellulosic biomass - Cellulosic biomass is the fibrous, woody, and generally inedible portions of plants that make up 75 percent or more of all plant material. Bioethanol and biobutanol are produced from cellulosic biomass. Typically, cellulosic biomass is derived from readily available sources such as perennial grasses like switchgrass, plant wastes and even sawdust. Cellulosic biomass is cheap, it doesn't compete with food crops and estimates have put the level of production from cellulosic biomass as high as 2,000 gallons of renewable petroleum per acre. There are two ways of producing alcohol from cellulose : Cellulolysis processes which consist of hydrolysis on pretreated lignocellulosic materials, using enzymes to break complex cellulose into simple sugars such as glucose and followed by fermentation and distillation. Gasification that transforms the lignocellulosic raw material into gaseous carbon monoxide and hydrogen. These gases can be converted to ethanol by fermentation or chemical catalysis. They both include distillation as the final step to isolate the pure ethanol.
Cetane number - Biodiesel from tallow has a higher cetane number than plant oil biodiesel. This means cleaner and more efficient burning in diesel engines.
Chemical transesterification - Biodiesel can be produced from any non mineral oil or fat through transesterification, a reaction with alcohol and a catalyst. The products of the reaction are an ester (biodiesel) and glycerol. A variation of the transesterification reaction has been used for centuries to produce soap but modern biodiesel production plants use a very fast, high pressure and temperature continuous process.
Cloud point - Due to the high levels of saturates, biodiesel from tallow tends to crystallise out at much higher temperatures than biodiesel from plant oils. In Northern Europe this makes tallow biodiesel unsuitable for winter use apart from blending at low rates into conventional diesel. Tallow diesel cannot meet the required DIN standard for 100% biodiesel, but as a 5% mix with conventional diesel it meets the required standards. Cloud point defines the temperature at which a clear diesel fuel becomes hazy or cloudy due to the formation of wax crystals.
Cold Filter Plugging Point (CFPP): An indicator of the temperature at which the precipitation of wax crystals in distillate fuel may lead to blocking or plugging of equipment filters and fuel lines.
Cold-flow standards - Biodiesel specifications in New Zealand are controlled by a voluntary Standard NZS 7500:2005 Automotive Biodiesel - Specification for manufacturing and blending. While biodiesel is generally considered to be similar to mineral diesel there are some key differences which need to be considered as part of a diesel / biodiesel blend. These properties are density, viscosity and cold flow (cloud point and cold filter plugging point or CFPP). Biodiesel, particularly when made from tallow, is known to have poor cold flow properties. While cold flow properties are specified in the PPSR all oil companies in New Zealand choose to provide diesel with more stringent cold flow properties. See here for more details on cold flow.
Continuous Flow - The advantages of continuous reactors include product consistency, safety, and more efficient design options for the reactor and ancillary processes such as glycerol separation. The key feature of the process is its ability to operate continuously with a high reaction rate, potentially requiring less post reaction cleaning and product/reactant separation than currently established processes.
Denaturant : A substance added to ethanol to make it undrinkable, or unsuitable for human consumption, e.g. petrol.
EN 14214 : Automotive fuels - Fatty acid methyl esters (FAME) for diesel engines – Requirements and test methods.
FAEE : Fatty acid ethyl ester, biodiesel produced by ethanol esterification of natural product fatty acids.
FAME : Fatty acid methyl ester, biodiesel produced by methanol esterification of natural product fatty acids.
Fermentation - Ethanol is currently produced from starch and sugar based products which are fermented to form a dilute alcohol. Various grades of industrial, beverage and fuel grade ethanol are then distilled from the initial dilute solution.
Fuel Quality Monitoring Programme (FQMP) : Responsibility of the Measurement and Product Safety Service, a group within the Ministry of Economic Development. It routinely tests petrol and diesel samples from around the country to monitor that the fuel available to consumers complies with the regulations.
FVI : Flexible Volatility Index is a function of VP and E70. It is an indicator of hot running performance, or the tendency for fuel to vaporise in the fuel lines when the engine is hot (known as vapour lock) and impede fuel flow.
Gasification - Interest is currently growing in the use of biomass gasification products to produce Fischer-Tropsch liquids (FTLs). These liquids may eventually be produced at similar prices to petroleum-based diesel. FTL formulations tend to be cleaner burning than petroleum-based diesel.
Glycerides: Esters formed from glycerol and fatty acids. Glycerol can be esterified with one, two or three fatty acids to form monoglycerides, diglycerides and triglycerides.
Glycerol (or glycerine): An alcohol that is the main by-product of the transesterification process. Biodiesel may contain free glycerol and/or bound glycerol (i.e. contained in the mono-, di- and triglycerides).
Hydrous ethanol: Neat ethanol that has a higher water content than "anhydrous" ethanol, and is therefore generally unsuitable for blending with petrol.
Hydrolysis/Fermentation - Advances in the hydrolysis/fermentation of ligno-cellulose to produce ethanol/methanol and lignin are promising, with future cost reductions claimed. The alcohol fuels can be used in present designs of internal combustion engines, new micro-turbines, or as a source of hydrogen for fuel cells.
Minimum ester content - Conventional processing methods require a much higher quality tallow in order to meet the Engine Fuels Specifications Regulations minimum ester content and cold-flow standards.
NZS 7500: The New Zealand Standard on Automotive Biodiesel – Specification for Manufacturing and Blending.
Polymerise: The chemical reaction in which a compound is made into a polymer, which is a natural or synthetic compound that consists of large molecules made of many chemically bonded smaller identical molecules.
Pr EN 15376: Automotive fuels - Ethanol as a blending component for petrol.
Pyrolysis - Pyrolysis processes provide greater flexibility and higher conversion efficiencies compared to combustion, but capital costs are also currently excessive and technology is in the early stages of development. The product, pyrolysis oil, which can be used in turbines and other heat plant, can be easily transported and thus allows separation of the resource location from the site of use.
Reactive Distillation - Reactive Distillation is a continuous process in which the chemical reactions and product separations occur simultaneously in the one unit.
Rendering - Rendering is the boiling down of waste scraps of meat, fat, bone and other animal tissues at meat processing plants to produce meat meal and tallow.
Saturated fatty acids: All carbons contain as many hydrogens as possible (hence a saturated fat is 'saturated' with hydrogen atoms). The fatty acids do not contain any double bonds or other functional groups along the chain.
Tallow - Tallow is the fat fraction from the rendering process. It is produced in two main grades – edible grade for human consumption as cooking fat or in baked products, and inedible grade that is made into soap, candles and waxes. New Zealand rendering systems are generally advanced and well managed, and consequently NZ tallows command a premium on world markets. See guide to buying tallow here.
Tallow methyl esters manufacture - Biodiesel is formed when tallow (triglycerides) is heated in the presence of methanol and an alkaline catalyst to produce methyl esters (biodiesel) and glycerol.
Unsaturated fatty acids: A fat or fatty acid in which there are one of more double bonds in the fatty acid chain (hence eliminating hydrogen atoms). A fat molecule is monosaturated if it contains one double bond and polyunsaturated if it contains more than one double bond. The greater the degree of unsaturation in a fatty acid (i.e. the more double bonds in the fatty acid), the more vulnerable it is to oxidative degradation.
Vapour pressure (VP): This is a measure of the pressure exerted by the vapours delivered from a liquid at a given temperature and pressure.
Something missing here? Contact us with your suggestions to make this list of technical terms more helpful.
Biofuels - Issues of Concern
- Sustainability and the Food vs Fuel debate
- EECA report on sugar cane sustainability
- EECA report on rising food prices and biofuels
- Quality biofuels
- Toxic Jatropha? - Putting it into Perspective
- Canola Oil / Rapeseed Oil – The facts
EECA Report: Sustainability and the Food vs Fuel debate, February 2008
Click here to view the report on Consumer Information and Biofuel Sustainability.
EECA Report : The Sustainability of Brazilian Sugarcane Bioethanol - A Literature Review, May 2008
The Energy Efficiency and Conservation Authority (EECA) sought an independent international literature review into the sustainability of Brazilian sugarcane biofuel pending the introduction of legislation requiring oil companies to sell a percentage of biofuel in order to reduce New Zealand's carbon footprint. The literature review confirmed that Brazilian sugarcane biofuel is environmentally sustainable. Click here for further details and a link to the report on EECA's website.
EECA Report : Rising Food Prices and Biofuels, September 2008
The Energy Efficiency and Conservation Authority (EECA) together with Ministry of Agriculture and Forestry (MAF) Policy sought an international review of literature to better understand the causes of rising food prices and their linkage (if any) to biofuels production. This review aims to inform the New Zealand debate on the impact of first generation biofuels on food prices. Click here for further details and a link to the report on EECA's website.
Quality biofuels
Whilst it might seem like a good idea, trying to make your own biodiesel or even running your car on vegetable oil is not a good idea. EECA reports that overseas studies and local experience show there is a risk of damage to your engine when using straight vegetable oil, including when the engine has been modified with a conversion kit. Fuel quality is a key issue and EECA recommends only buying from sellers who are able to demonstrate that they are complaint with the Engine Fuel Specifications Regulations 2008.
Toxic Jatropha? Putting it into perspective
Media reports have recently suggested that Jatropha poses a serious threat to livestock [Carbon News Farmers fear fuel-source jatropha will kill stock - Tuesday 27 Jan 09 9:00am - Plans to grow the biofuel stock plant jatropha in New Zealand could run into opposition from farmers who fear it could kill their animals and become another “gorse” and JATROPHA: Toxic seeds could fool children - Friday 30 Jan 09 9:00am - The toxic seed of the jatropha plant – used to make biofuel - might be attractive to children, warns a New Zealand scientist.”
LBIG Convener Andre Hamman notes
“Jatropha is indeed poisonous but to imply that this could cause a significant safety issues is a matter of assessing the risk by considering aspects of incidence, probability and severity. A comparable plant would be Ricinus communis which is grown to produce commonly consumed "castor oil". The plant is treachous in that even touching the leaves during harvesting can cause human ill health. The cold pressing and filtering process removes the toxin Ricin. According to the NZ Biosecurity website this species may be freely imported into NZ. I myself have seen this plant growing in many places in gardens and roadsides within the Bay of Plenty and Auckland/Waikato areas.”
Of interest, the following common plants in NZ have the following toxicity/risk rating:
- + Arum lilies, Macrocarpa, Oak, Potatoes (all green parts), Rhubarb (leaves)
- ++ Ivy, Karaka tree, Kowhai, Pororporo, Ngaio, Lantana, Lillies, Daffodils, Castor oil Plant
- +++ Tutu, Hemlock, Foxglove
- ++++ Laburnum, Deadly Nightshade
- +++++ Oleander, Yew, Rhododendron Azalea
Andre went on to note,
”Whilst I am not qualified to offer an assessment of the toxicity/risk profile for Jatropha, I do recall comparisons made internationally between Jatropha and the Castor Oil plant. Generally on the international circuit, the view is that Jatropha presents a lower risk. On this basis Jatropha would have a risk rating of ++ or +.
With regards to media comment that Jatropha may kill stock I can only imagine that this would be the result of ‘force feeding’ the animals. Jatropha curcas has been used for centuries in Africa as a stock barricade. In my own experience, I have grown my Jatropha plants in a paddock with sheep. They simply leave the plants alone.”
Canola Oil / Rape Seed Oil – The facts
The internet is awash with information both good and bad in relation to Canola Oil. This site explains most issues http://www.canola-council.org/biodiesel/.
International Issues of Interest
Coming soon...