Biodiesel production in the United States has been increasing dramatically recently, from 500,000 gallons in 1999 to 30 million gallons in 2004. The federal biodiesel tax incentive that went into effect January 2005 is causing biodiesel demand to climb even more and encourages entrepreneurs to invest in more biodiesel production facilities. The immediate production capacity of biodiesel is estimated to be 150 million gal/yr; this capacity can be doubled or tripled in a time frame of 12 months.
The principal by-product of biodiesel production is glycerol, also known as glycerin. It occurs in vegetable oils at a level of approximately ten percent by weight. For each gallon of biodiesel produced, approximately 0.34 kg (0.68 lb) of crude glycerol is produced. High purity glycerol is a very important industrial feedstock. Larger scale biodiesel producers refine their crude glycerol and move it to markets in other industries. If it is used in food, cosmetics, and drugs, further purifications are needed such as bleaching, de-odoring, and ion exchange to remove trace impurities. Purifying it to that stage, however, is very costly and generally out of the range of economic feasibility for the small to medium sized plants.
As more and more crude glycerol is continuously generated from the biodiesel industry, it is very important that economical ways of the low-grade glycerol utilization be explored to further defray the cost of biodiesel production in the growing global market.
To explore a novel way to utilize the low-grade glycerol, this project involves conducting a feasibility study to convert glycerol to short-chain monohydric alcohols, such as methanol and ethanol or their mix, for application back to the biodiesel production process. The method will be thermochemical conversion, e.g, thermal cracking or pyrolysis and liquefaction.
Other products that are also possibly derived from this process include methane, n-propanol), i-propanol), and char. Therefore, the specific objectives are to:
- explore whether controlled thermal cracking of glycerol alone is suitable for alcohol conversion,
- determine the feasibility of hydro-thermal cracking of glycerol for targeted alcohols, and
- evaluate process parameters to maximize alcohol production.