Wanted: Glycerine By-Product

Introduction

Worldwide market for biodiesel is poised for explosive growth in the next decade. The sharp rise in biofuels has created an increasing supply of glycerol.

Glycerine also known as Glycerol has many commercial and industrial uses, and is generally considered a relatively valuable product. In order to both improve the economics of biodiesel production process and put this waste stream to good use, new markets must be found. There are several ways in which this might happen, but biodiesel producers need to make this a priority if they are to reap the benefits of this unused resource.

Biodiesel is a fast growing product in both the United States and Europe as government policies seek to spur the development of renewable transportation fuels. In the US alone since 2004, biodiesel production has grown from 75 million gallons per year to 650 million gallons per year in 2008 (Biodiesel 2020, 2008). While the production of biodiesel is beginning to have an effect on the liquid fuels market, it has already had an enormous effect on the market for another product, glycerol.

When bio-crude goes through the transesterification process to become biodiesel, a significant amount of glycerol is produced as a by-product of the chemical reaction. This transesterification process yields 100kg of glycerol for every metric tonne of biodiesel produced, a 10% yield (Glycerol Challenge, 2009). Total world biodiesel production in 2008 was estimated to be roughly 12.24 million metric tonnes, and this number is rapidly growing (Biodiesel 2020, 2008). This means that 1.224 million metric tonnes of crude glycerol was produced from the biodiesel conversion processes alone. The total world market for refined glycerol was estimated to be roughly 900,000 metric tonnes in 2005 (Impact of Biodiesel Production on the Glycerol Market, 2006). It is apparent that we are already facing a global glut of glycerol, a glut which is certain to worsen before it can improve.

Compare this market effect to the market for one of the major by-products of the distillation of ethanol from corn, dried distillers grains and solvents (DDGS). DDGS are commonly used in animal feeds around the world, and have select additional uses. With the recent ramping up in corn-based ethanol production throughout the world, mostly occurring in the U.S., DDGS stocks have risen sharply. However, looking at overall potential U.S. demand for DDGS, there seems to still be some room for market growth in this area, which will continue to keep the economics of ethanol more attractive until it hits this ceiling and DDGS prices begin to fall. The table attached below shows the global markets for both glycerol and DDGS (Christiansen, 2009). 

These estimates are a simplification, as the true markets are slightly different, but they depict the overall trend accurately. The crude glycerol market is tapped out at the moment, but not necessarily for the reasons that we might initially suppose.

Economic Factor 

This market glut has had a mixed effect on prices of glycerol worldwide depending upon whether one looks at the crude or refined product. Glycerol taken from the biodiesel production process is about 80% pure, whereas refined glycerol is at 99.5% purity, after undergoing a highly energy intensive refining process. With the rapid rise in the availability of crude glycerol worldwide due to biodiesel production, there has been a refining bottleneck, as current refineries have hit the limits of their capacity. As such, the prices for refined glycerol have not varied inversely with biodiesel production, as might be expected. Instead, prices halved between 2003 and 2006, while growing 69% between July 2007 and July 2008 as a result of other exogenous factors (Soyatech, 2008). Prices for crude glycerol, on the other hand, have fallen through the floor, dropping close to zero and even negative as producers are forced to pay to have it taken away from their plants and incinerated (Impact of Biodiesel Production on the Glycerol Market, 2006). This may only be a short term trend, however. Glycerol is not a waste product, and in fact has been a staple chemical compound in the world economy for many years. There is reason to believe that as refining capacity catches up to the supply of the crude product, and new uses for glycerol are found, its price may rebound, potentially improving the economics of biodiesel production.

Uses of Glyrecol 

Glycerol is used for a variety of purposes across many different industries. The following is a list of current uses of glycerol:

• Food – glycerol is used as an artificial sweetener, especially in low-fat foods, since it is better for blood pressure than sugar. It is also used as a thickening agent and an ester in shortenings and margarine. It also can be used as a substitute ingredient in animal feed.
• Basic Materials – Glycerol be used as a substitute for petroleum-based polypropelene, a textile, and in both rigid and flexible industrial foams. It is also used as a building block for many different kinds of industrial chemicals.
• Pharmaceuticals – Used as an additive in cough syrup, toothpaste, skin care, hair care soap and many others.
• Explosives – The compound nitroglycerin, made with glycerol, is commonly used in all types of explosives.
• Other – Used as an ingredient in antifreeze, hydraulic fluids, plasticizers (List assembled from many different sources)

While glycerol appears to be quite a versatile substance, one that might be able to withstand slack demand in any one or two categories, it is unclear whether any of these markets possess the necessary elasticity to soak up the extra supply due to biodiesel production. The falling price of crude glycerol could cause some glycerol-based products to substitute for other similar products derived from other sources, but this market shift is not guaranteed to happen, and its magnitude is impossible to predict. But the bottoming of the glycerol market has led to increasing focus on finding these substitutes.

Other Uses

Sheeps being fed Glycerine

  ->As Animal Feed

 

For instance, researchers at the University of Arkansas’ Center of Excellence for Poultry Science have initiated studies that substitute glycerol in chicken feed. The study showed that up to 5% substitution of glycerol in chicken feed showed no negative effects on growth. Given the immense volume of the global poultry feed market, not to mention the entire animal feed market, this is a huge potential growth area for refined glycerol. While this will not necessarily provide direct benefits to a biodiesel producer, since this application depends upon a low price of crude and refined glycerol, this does provide larger economic benefits to society.

-> Energy Feedstock

An even greater upside to the bottoming of glycerol prices has been exploration into its use as an energy feedstock for example as fuel for diesel engines. As reported in TCE magazine in an article "(E)mission Impossible" by Paul Day, John McNeil and Felix Sirovski. 

Problems with using it as a fuel in diesel engines: Glycerine seems to be barely combustible, too viscous and if combusted, produces lots of toxic acrolein which ends up clogging the exhaust with polymers. But these guys have an actual standard 40 kWh Deutz engine running on glycerine by just increasing both the inlet air temperature during engine operation from 60°C to 200°C and mass flow. This overcomes the problem glycerine poses on the diesel engine.

In fact, it was found that glycerine is a better fuel, Firstly because it is not toxic as mentioned before that it is used as a sweetener in liqueurs. Secondly, it is water soluble, easy to wash away if spilled. Thirdly, it is nearly impossible to ignite under normal conditions which gives it a two thumbs up for safety. As for Its viscosity, at 90°C, the viscosity drops dramatically to a level similar to fuel oil of 13 centistokes.

Compare glycerine to other fuels, its calorific value is not that high. Its a mere 16.2MJ/kg whilst diesel has 42MJ/kg and Biodiesel has 37.8MJ/kg. The comparison of prices does not look too bad, in fact, it could be relatively cheaper fuel especially with Renewable Obligation Certificates(ROC) in the UK and other Renewable commitments in Europe. 

Conclusion

The above post suggest that there is still potential for the economics of the biodiesel conversion process to improve if more markets can be found for crude and refined glycerol. This is a valuable and versatile feedstock with many different uses, not only for high-value uses, but also potentially as an energy feedstock which needs for research. It is important that biodiesel producers focus as much on their by-products are their core products if they seek to maximize the value and efficiency of the conversion process. Glycerol production is only going to increase, so it is important for us to find something useful to do with it.