How biomass energy works: How to Make Biodiesel

How biomass energy works is evolving, and is catching on like wild fire across the planet. 

Farmers, scientists, and governments everywhere have opened their eyes to the wonders of what we humans can do with the bioenergy resources our planet offers us.

With worries over global climate change mounting, the days when people accepted crude oil as the only option are rapidly dying off. 

In fact, in many regions, biodiesel is sold at a much cheaper rate than conventional diesel. 

Bad news for the big oil companies?

I would say so!

Grow oil crops, make biodiesel, feed the animals & save money! Vermont farmer and owner of State Line Biofuels, John Williamson and Chris Callahan, University of Vermont Extension show us how.

In this article we will cover the basics of how biomass energy works when making biodiesel. 

In the above right hand corner is a video that shows you how biodiesel can be manufactured on a farm.  

It’s really cool, so check it out!

How Biomass Energy Works: Biodiesel

Common feedstock used in biodiesel production includes yellow grease (recycled vegetable oil), "virgin" vegetable oil, and tallow.

Recycled oil is processed to remove impurities from cooking, storage, and handling, such as dirt, charred food, and water.

Virgin oils are refined, but not to a food-grade level.

Degumming to remove phospholipids and other plant matter is common, though refinement processes vary.

Regardless of the feedstock, water is removed as its presence during base-catalyzed transesterification causes the triglycerides to hydrolyze, creating salts from the fatty acids instead of producing biodiesel.

A sample of the cleaned feedstock oil is titrated with a standardized base solution in order to determine the concentration of free fatty acids present in the vegetable oil sample.

These acids are then either esterified into biodiesel, esterified into glycerides, or removed, typically through neutralization.

Base-catalyzed transesterification creates a reaction between lipids (fats and oils) and alcohol (typically methanol or ethanol) to produce biodiesel and an impure coproduct, glycerol.

If the feedstock oil is used or has a high acid content, acid-catalyzed esterification can be used to create a reaction between fatty acids and alcohol to produce biodiesel.

Other methods, such as fixed-bed reactors, supercritical reactors, and ultrasonic reactors, eliminate or decrease the use of chemical catalysts.

Products of the reaction include not only biodiesel, but also byproducts, such as soap, glycerol, excess alcohol, and trace amounts of water.

All of these byproducts must be removed to meet industry standards, but the order of removal is process-dependent.

The density of glycerol is greater than that of biodiesel, and this difference is used to separate the bulk of the glycerol co product.

Residual methanol is typically recovered by distillation and reused. Soaps can be removed or converted into acids. Residual water is also removed from the fuel.

How Biomass Energy Works: Biodiesel Production methods

Supercritical process

An alternative, catalyst-free method for transesterification uses supercritical methanol at high temperatures and pressures in a continuous process.

In the supercritical state, the oil and methanol are in a single phase, and reaction occurs spontaneously and rapidly.

This process can tolerate water in the feedstock, and free fatty acids are converted to methyl esters instead of soap.

So a wide variety of feedstocks can be used, and the catalyst removal step is eliminated.

High temperatures and pressures are required, but energy costs of production are similar or less than catalytic production routes.

Ultra- and high-shear in-line and batch reactors

Ultra- and High Shear in-line or batch reactors allow production of biodiesel continuously, semi- continuously, and in batch-mode. This drastically reduces production time and increases production volume.

The reaction takes place in the high-energetic shear zone of the Ultra- and High Shear mixer by reducing the droplet size of the immiscible liquids such as oil, fats, and methanol.

Ultrasonic reactor method

In the ultrasonic reactor method, the ultrasonic waves cause the reaction mixture to produce and collapse bubbles constantly. This cavitation provides the mixing and heating required to carry out the transesterification process.

Thus using an ultrasonic reactor for biodiesel production drastically reduces the reaction time, reaction temperatures, and energy input. Hence the process of transesterification can run inline rather than using the time consuming batch processing.

Industrial scale ultrasonic devices allow for the industrial scale processing of several thousand barrels per day.

Lipase-catalyzed method

Recent research on how biomass energy works has focused on the use of enzymes as a catalyst for the transesterification. Researchers have found that very good yields could be obtained from crude and used oils using lipases.

The use of lipases makes the reaction less sensitive to high FFA content, which is a problem with the standard biodiesel process.

One problem with the lipase reaction is that methanol cannot be used because it inactivates the lipase catalyst after one batch. However, if methyl acetate is used instead of methanol, the lipase is not in-activated and can be used for several batches, making the lipase system very cost effective.

Related Articles:

How Biomass Energy Works

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Biomass Energy Resources: Vermont's Sustainable Energy Model

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How Bioenergy is Being Used In Schools Around the World

Biomass Energy Company: 3 Biomass Innovators

Biomass Renewable Energy Benefits

Problems with Biomass Energy

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