Bioenergy PROFITS Principles: Bio This and Bio That….So What is Biodiesel Anyway?

By Biofuels Digest columnist Dr. Rosalie Lober

Unless you’re working daily in the field of biofuels, you will probably do research to learn the specifics of the variety of fuel options, feedstocks and technologies.  How will you do this without becoming overwhelmed?  Today, let’s explore some of the actions you can take when you want to find out more about biodiesel.

• Decide what you’re looking for
• Clarify your purpose

As you consider your purpose for exploring data and vital information, let’s differentiate between them.  Data (datum in plural) refers to facts.  When you process, organize and structure data, it can become useful information.  Information is ‘transformed data’ that businesses exploit to find patterns, trends and other ways to supplement knowledge they may have.

Decide what you’re looking for

First, are you researching biodiesel for business or for personal interest?  Your focus will differ depending upon your purpose.  For business, you may choose a more rigorous search and timeframe.  Deciding what you’re looking for is certainly the most likely way to obtain the vital information you want.

How can we make sense of all the data available to us?  And how often do we sidestep what we are looking for and start along a new path, ending up more confounded than before?  We seduce and distract ourselves on the internet by following links that are only marginally related to what we need.  We rationalize that these voyages will offer a greater understanding of our subject.  This may be true, yet another hour or more slips away on an unplanned adventure.  Usually other work, dinner or sleep is the casualty of these indulgences.

As stated earlier, today we want to find out about biodiesel.  The most obvious question to ask is:  What is it?

What Is Biodiesel?

Biodiesel is an alternative fuel similar to conventional or ‘fossil’ diesel. Biodiesel can be produced from straight vegetable oil, animal oil/fats, tallow and waste cooking oil. The process used to convert these oils to Biodiesel is called transesterification. This process is described in more detail below.

The largest possible source of suitable oil comes from oil crops such as rapeseed, palm or soybean. In the UK rapeseed represents the greatest potential for biodiesel production. Most biodiesel produced at present is produced from waste vegetable oil sourced from restaurants, chip shops, industrial food producers such as Birdseye etc.  Though oil straight from the agricultural industry represents the greatest potential source it is not being produced commercially simply because the raw oil is too expensive.  After the cost of converting it to biodiesel has been added on it is simply too expensive to compete with fossil diesel. Waste vegetable oil can often be sourced for free or sourced already treated for a small price.  The waste oil must be treated before conversion to biodiesel to remove impurities.  The result is Biodiesel produced from waste vegetable oil can compete with fossil diesel.

What are the benefits of Biodiesel?

Biodiesel has many environmentally beneficial properties.  The main benefit of biodiesel is that it can be described as ‘carbon neutral’.  This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2).  This effect occurs because when the oil crop grows it absorbs the same amount of CO2 as is released when the fuel is combusted.  Also, CO2 is released during the production of the fertilizer required to fertilize the fields in which the oil crops are grown.

Fertilizer production is not the only source of pollution associated with the production of biodiesel.  Other sources include the esterification process, the solvent extraction of the oil, refining, drying and transporting. All these processes require an energy input either in the form of electricity or from a fuel, both of which will generally result in the release of green house gases.  To properly assess the impact of all these sources requires use of a technique called life cycle analysis. Biodiesel is rapidly biodegradable and completely non-toxic, meaning spillages represent far less of a risk than fossil diesel spillages. Biodiesel has a higher flash point than fossil diesel and so is safer in the event of a crash.

Clarify your purpose

The babble of extraneous data can distract you for days.  When you clarify your purpose for seeking data, you reinforce what is important for you to know.  You can begin by asking the following questions:

• What do I want to accomplish?

ü     Is there an underlying problem or opportunity for me that requires a solution?

ü     If so, what information is currently missing?

ü     What are my knowledge gaps on ‘x’?

ü     How will additional data help me solve this?

These questions help to focus your pursuit of data.  The answers will reinforce your commitment to what you want to know.  If the information is important for business, then these questions will help with your strategic direction or suggest alternative positioning for your business.  With this clarity, you can search more effectively for information to help serve your customers and clarify the core capabilities you need for the future of your business.

Continuing with our search for information about biodiesel, let’s find out about how it is produced.

Biodiesel Production

As mentioned above biodiesel can be produced from straight vegetable oil, animal oil/fats, tallow and waste oils.  There are three basic routes to biodiesel production from oils and fats:

• Base catalyzed transesterification of the oil.
• Direct acid catalyzed transesterification of the oil.
• Conversion of the oil to its fatty acids and then to biodiesel.

Almost all biodiesel is produced using base catalyzed transesterification as it is the most economical process requiring only low temperatures and pressures and producing a 98% conversion yield.

The Transesterification process is the reaction of a triglyceride (fat/oil) with an alcohol to form esters and glycerol. A triglyceride has a glycerine molecule as its base with three long chain fatty acids attached.  The characteristics of the fat are determined by the nature of the fatty acids attached to the glycerine. The nature of the fatty acids can in turn affect the characteristics of the biodiesel.  During the esterification process, the triglyceride is reacted with alcohol in the presence of a catalyst, usually a strong alkaline like sodium hydroxide.  The alcohol reacts with the fatty acids to form the mono-alkyl ester, or biodiesel and crude glycerol.  In most production methanol or ethanol is the alcohol used (methanol produces methyl esters, ethanol produces ethyl esters) and is base catalysed by either potassium or sodium hydroxide.  Potassium hydroxide has been found to be more suitable for the ethyl ester biodiesel production, either base can be used for the methyl ester. A common product of the transesterification process is Rape Methyl Ester (RME) produced from raw rapeseed oil reacted with methanol.

A successful transesterification reaction is signified by the separation of the ester and glycerol layers after the reaction time.  The heavier, co-product, glycerol settles out and may be sold as it is or it may be purified for use in other industries, e.g. the pharmaceutical, cosmetics etc.

Straight vegetable oil (SVO) can be used directly as a fossil diesel substitute however using this fuel can lead to some fairly serious engine problems.  Due to its relatively high viscosity SVO leads to poor atomisation of the fuel, incomplete combustion, coking of the fuel injectors, ring carbonisation, and accumulation of fuel in the lubricating oil.  The best method for solving these problems is the transesterification of the oil.

The engine combustion benefits of the transesterification of the oil are:

• Lowered viscosity
• Complete removal of the glycerides
• Lowered boiling point
• Lowered flash point
• Lowered pour point

Production Process

You may also want to understand the complexity of the Biodiesel Production Process.

~      Mixing of alcohol and catalyst
The catalyst is typically sodium hydroxide (caustic soda) or potassium hydroxide (potash).  It is dissolved in the alcohol using a standard agitator or mixer. Reaction.  The alcohol/catalyst mix is then charged into a closed reaction vessel and the oil or fat is added.  The system from here on is totally closed to the atmosphere to prevent the loss of alcohol. The reaction mix is kept just above the boiling point of the alcohol (around 160 °F) to speed up the reaction and the reaction takes place. Recommended reaction time varies from 1 to 8 hours, and some systems recommend the reaction take place at room temperature.  Excess alcohol is normally used to ensure total conversion of the fat or oil to its esters.  Care must be taken to monitor the amount of water and free fatty acids in the incoming oil or fat. If the free fatty acid level or water level is too high it may cause problems with soap formation and the separation of the glycerin by-product downstream.

~      Separation
Once the reaction is complete, two major products exist: glycerin and biodiesel.  Each has a substantial amount of the excess methanol that was used in the reaction.  The reacted mixture is sometimes neutralized at this step if needed.  The glycerin phase is much more dense than biodiesel phase and the two can be gravity separated with glycerin simply drawn off the bottom of the settling vessel.  A centrifuge can be used to separate the two materials faster.

~      Alcohol Removal
Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by distillation.  In others systems, the alcohol is removed and the mixture neutralized before the glycerin and esters have been separated.  In either case, the alcohol is recovered using distillation equipment and is re-used.  Care must be taken to ensure no water accumulates in the recovered alcohol stream.

~      Glycerin Neutralization
The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerin.  In some cases the salt formed during this phase is recovered for use as fertilizer.  In most cases the salt is left in the glycerin.  Water and alcohol are removed to produce 80-88% pure glycerin that is ready to be sold as crude glycerin.  In more sophisticated operations, the glycerin is distilled to 99% or higher purity and sold into the cosmetic and pharmaceutical markets.

~      Methyl Ester Wash
Once separated from the glycerin, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage.  In some processes this step is unnecessary. This is normally the end of the production process resulting in a clear amber-yellow liquid with a viscosity similar to petrodiesel.  In some systems the biodiesel is distilled in an additional step to remove small amounts of color bodies to produce a colorless biodiesel.

~      Product Quality
Prior to use as a commercial fuel, the finished biodiesel must be analyzed using sophisticated analytical equipment to ensure it meets any required specifications.  The most important aspects of biodiesel production to ensure trouble free operation in diesel engines are:

-        Complete Reaction

-        Removal of Glycerin

• Glycerin (a valuable byproduct usually sold to be used in soaps and other products).

-        Removal of Catalyst

-        Removal of Alcohol

-        Absence of Free Fatty Acids

Is biodiesel or ethanol better for the environment?

Both forms of biofuel have definite environmental advantages over petroleum-based gasoline and diesel fuel.

According to the RFA, “Ethanol contains 35% oxygen.  Adding oxygen to fuel results in more complete fuel combustion, thus reducing harmful tailpipe emissions. Ethanol also displaces the use of toxic gasoline components such as benzene, a carcinogen.  Ethanol is non-toxic, water soluble and quickly biodegradable.

Biodiesel, on the other hand, is the only alternative fuel to have fully completed the health effects testing requirements of the Clean Air Act.  The use of biodiesel in a conventional diesel engine results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel.  In addition, the exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to diesel.

In Summary

There is a lot more you can learn about biodiesel.  If you want to continue in this exploration remember to take the following actions:

• Decide what you’re looking for
• Clarify your purpose

Obtain Vital Information is one of the Bioenergy PROFITS Principles, highlighted in Dr. Rosalie Lober’s, newly released book, Run Your Business like a Fortune 100: 7 Principles for Boosting PROFITS.  Learn here, how you can apply some of the best practices and proven principles of successful biofuels companies for running your business most effectively in this current world of climate change and renewable energy.

Bioenergy PROFITS Principles: Bio This and Bio That….So What is Biodiesel Anyway? is a post from: Biofuels Digest