Example – glycerol from biodiesel

Generic product activity or name

Glycerin, glycerine.

Context and background
Recent years have seen a marked increase in biodiesel production. The global biodiesel market is estimated to exceed 30 billion liters by 2015 (and 40 billion liters by 2023)(OECD 2011). This biodiesel production generates on average 10% (w/w) glycerol as the main by-product (Fan et al. 2010). Earlier, glycerol was produced mainly using synthetic processes but now the biodiesel route is dominating. The process is a base-catalysed trans-esterification that reacts lipids with alcohol to produce biodiesel and the by-product glycerol.

This dependent co-product is not fully utilised, which implies that some of it has to go to waste treatment since there is no other demand for it – it is a “near-waste”.

Presentation of example
The crude glycerol has a low price and it has been speculated (Yang et al. 2012) that in the future an increased focus on value-added uses for crude glycerol may increase the biodiesel production by covering some of the productions costs by an increasing income from glycerol. Purified glycerol is a high-value chemical with many uses and thus the crude glycerol by-product may present opportunities for new applications (Fan et al. 2010).

But in the current situation, production of crude glycerol far exceeds the market requirements, so that part of it has to go to some kind of storage or waste treatment. This implies that the waste treatment is the marginal use. Due to its high heating value, the marginal treatment of glycerol is typically incineration with heat recovery. Thus, an additional amount of glycerol produced will lead to an increase in glycerol incineration by the same amount. An increased amount of glycerol used for industrial uses will likewise reduce the incineration by a similar the amount.

For glycerol as for many other “near waste” by-products, it can be observed that after a while a new market will probably develop that makes better use of the ”near-waste”, shifting the marginal use from being a waste treatment to another production.

Information sources used
The analyses from OECD are a good starting point for agricultural products such as biodiesel. For information on glycerol Ullmann’s Encyclopedia of Industrial Chemistry is a good starting point.

Fan X, Burton R, Zhou Y (2010). Glycerol (Byproduct of Biodiesel Production) as a Source for Fuels and Chemicals – Mini Review. The Open Fuels & Energy Science Journal 3:17-22. http://benthamopen.com/toefj/articles/V003/17TOEFJ.pdf (accessed January 14, 2015).

OECD (2011). FAO agricultural Outlook 2011-2022. http://www.oecd.org/site/oecd-faoagriculturaloutlook/48178823.pdf (accessed January 14, 2015).

Yang A, Hanna M A, Sun R (2012). Value-added uses for crude glycerol–a by-product of biodiesel production. Biotechnology for Biofuels 5(13) (http://www.biotechnologyforbiofuels.com/content/5/1/13 (accessed January 14, 2015).

Author of this example
Bo Weidema


How to reference this
Weidema B P (2014), Example –glycerol from biodiesel. Version: 2015-01-15 www.consequential-lca.org