Ethanol is a renewable fuel made from starch- and sugar-based feedstocks or from cellulosic feedstocks. In U.S.A. corn is the most common feedstock used to produce ethanol. According to the US department of Energy nearly 97% of U.S. gasoline contains ethanol, typically E10 (10% ethanol, 90% gasoline), to oxygenate the fuel and reduce air pollution.

Compared with traditional methods, such as wet chemistry and HPLC, near infrared (NIR) spectroscopy provides considerable advantages in fuel ethanol industry quality control applications. The fundamental benefits include:

  • Eliminates costly consumables such as solvents, columns, and reagents.
  • Provides extremely fast results: generally less than 10 seconds measurement time per sample.
  • Allows simultaneous analysis of multiple components per sample.
  • Effectively eliminates sample preparation time.
  • Eliminates  many sources of systematic errors.

In the past decade, NIR has been successfully implemented in the fuel ethanol industry in four main areas:

1) Monitoring the quality of incoming grain. Moisture, starch, protein and oil content of corn can be easily measured, ensuring payment is for starch instead of moisture.

2) Fermentation process monitoring. NIR diffuse reflectance spectra of mash samples can be acquired in less than 10 seconds, which provides  real time monitoring of fermentation parameters, such as ethanol, sugar contents, lactic acid and glycerol, for the optimization of fermentation efficiency. NIR spectroscopy has also been proved to be a useful tool for troubleshooting the fermentation process and for the rapid and accurate evaluation of the performance of new enzymes, yeasts and nutritional supplements.

3) Distillate analysis. Transmission measurements of finished products can be used to make sure that they contain the correct amount of alcohol;

4) Dry house operations. Distiller’s dry grains (DDGS), the most valuable by-product of fuel ethanol plant, can be analyzed for protein, moisture, fat, fiber and ash content.

Galaxy Scientific’s QuasIR™ 4000 is ideal for fuel ethanol plant off-line analysis. The large sampling area integrating sphere is excellent for inhomogeneous solid samples such as incoming corn and DDGS, or suspension samples such as corn mash, while the transmission sample compartment is ideal for liquids such as distillates. Galaxy Scientific also offers QuasIR™ 2000 for on-line, real time measurements.