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Biodiesel

by Mr John Herbert | Director

Introduction

Biodiesel is a financially viable alternative to petroleum-based diesel. it is a renewable fuel that provides a real alternative for driving today's and tomorrow's fleet of diesel vehicles.

Possibly the greatest advantage, or benefit is that you can burn biodiesel today to power existing diesel engines in a sustainable way, without requiring any expensive modifications. This successful biofuel can also be blended with regular diesel helping to lower hydrocarbon consumption and lower tailpipe emissions.

Biodiesel is generally regarded as carbon-neutral because the carbon emitted when it is burned was absorbed from the atmosphere while the plant grew.

One disadvantage, if you can call it that, is that converting every vehicle on the planet is not possible, there is not enough land to grow sufficient fuel to completely replace the existing demand for diesel.

 

Other alternatives

In theory fuel cell technology (using hydrogen) is often cited as the solution, offering a zero emission solution eliminating tailpipe emissions completely. The process creates electricity and the only "emission" is water. However, there are plenty of barriers. Converting to a hydrogen based economy is fraught with difficulties, whereas biofuels, such as biodiesel, provided a simpler transition using existing technologies.

One might argue that trying to put fuel cell technology into vehicles is wasted effort, simply because handling and storing pressurised hydrogen is not an ideal solution. Based on best estimates, to provide similar vehicle range, the equivalent size hydrogen tank to provide the same range would be four to five times larger than today's fuel tank.

Origins

It is noteworthy to mention that Mr Diesel, the inventor of the diesel cycle, operated the very first diesel engine using vegetable oil.

Benefits

Converting to biodiesel technology offers a number of positive benefits:

  • its a renewable (a biofuel)
  • lowers tailpipe exhaust emissions
  • works with existing diesel engines
  • has similar properties to petrol diesel
  • its biodegradable

Creating biodiesel - the process

Biodiesel is sources from sustainable sources, created from vegetable oils and waste cooking oils that have a molecular structure that contains an ester group three times, called a tri-ester.

If we process this oil by reacting it with an alcohol, typically methanol, one type of ester is converted into another type of ester, this reaction is known as transesterification, more on that later.

It should be noted that during the process of producing biodiesel,  a marketable and saleable by-product glycerine is created. From a different perspective, biodiesel is a marketable product created from glycerine production. Smarter organisations gain competitive advantages from these synergies.

Feedstock

Biodiesel is processed from bulk vegetable oil or waste grease, this is known as the feedstock. The chosen feedstock, which comprises the bulk of the fuel components is a critical issue. There are two primary categories virgin (has not been used for any prior purpose) and recycled (used waste cooking oils).

Virgin sources primarily from agricultural crops include Canola (rape seed), sunflower, cottonseed, palm nut, soy bean and corn are some of the most common virgin feedstock's used for biodiesel production. The feedstock is important issue because you need a identify a reliable quality feedstock to ensure a financially successful plant.

Animal fats can also be used, for example tallow (solid rendered fat of cattle and sheep)  are also used in smaller quantities.

Transesterification

Transesterification is a simple chemical process, reacting a triglyceride molecule with an excess of alcohol in the presence of a catalyst (KOH, NaOH, NaOCN3, etc.) to produce glycerine and fatty esters. The result is biodiesel which can be burnt and or mixed with regular diesel to fuel diesel engines.

How is Biodiesel Used?

There are many ways to use alkyl esters including as solvents and as chemical intermediates for the formation of detergents. However, the application of most interest to us is as fuel.

Biodiesel Blends

Biodiesel can be used pure or blended with petroleum diesel.  For example, in Europe ALL diesel sold at the pump in France contains five percent (5%) biodiesel (B05).

We will take a closer look at three categories, although it should be remembered that any ratio of P-diesel/Biodiesel is feasible.

1.  Pure fuel (B100) Biodiesel can be used in its pure form, also known as neat biodiesel, or B100. This is the approach that provides the most reduction in exhaust particulates, unburned hydrocarbons, and carbon monoxide. It is also the best way to use biodiesel when its non-toxicity and biodegradability are important. Marine applications may also be important for B100 success.

Although neat biodiesel would not be expected to cause any operational problems, its solvent properties will be at their highest intensity and may cause problems with loosening of varnish deposits in fuel tanks and lines, degradation of fuel lines because some elastomers products (rubber) are not compatible with biodiesel minor modifications of older diesel vehicles maybe required.

Additionally, like its petroleum-based counterpart B100 biodiesel has poor flow characteristics at low ambient temperatures.

2.  Blends (typically 20-50%) Biodiesel will blend with petroleum-based diesel fuel in any proportion so it is common to use blends of 20 to 50% biodiesel in 80 to 50%.

Blends reduce the cost impact of biodiesel whilst providing some emissions reduction.  Emissions reductions are proportional to the percentage of biodiesel used. The cold flow and solvency problems noted with B100 are less of a concern when blends are used.

3.  As an additive, 1-2% (B02) Tests for lubricity have shown that biodiesel is a very effective lubricate. Even as little as 0.25% can has a measurable impact and 1-2% is enough to convert a very poor lubricity fuel into an acceptable fuel. Although these levels are too low to have any impact on the cetane number of the fuel or the tailpipe emissions, the lubricity provides a significant advantage at a modest cost.

 

Infrastructure

Another major advantage for biodiesel is that unlike fuel cells, it can take advantage of today's existing infrastructure, tanker delivery and storage of biodiesel is no different to existing fuel delivery, saving the effort and cost of creating additional fuel storage and delivery systems.

 

Cost Structures

Of course cost is crucial issue for every development, and biofuel is no different. However, costs vary considerably depending on the geographic location, type of biofuel, and technology used. With respect to feedstock, it goes without saying that costs are minimised when production and its usage happen in the same region.

 

Links

Since finding quality impartial information regarding biofuels can be hard work, and we like to make your life easier, we have included selected links below. Please note that Kelcroft is not responsible for the content or the veracity of external websites:

 

Further Information

For further information regarding Kelcroft's services, call today, our Hong Kong office telephone: +(852) 2335 9830, send us a fax +(852) 2335 9862, or send us an email message

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keywords: alternative renewable energy, biodiesel, biofuels