The need for producing environmentally friendly fuel alternatives to displace the use of petroleum in the U.S. has scientists at many research universities studying the feasibility of potential biofuel feedstocks.
At North Dakota State University, the feasibility of using new sugar beet varieties, known as energy beets, for ethanol production is under study. Energy beets have characteristics very similar to sugar beets used for table sugar production.
Sugar beets for table sugar production are stored conventionally in open piles for up to six months under extremely low temperatures. However, storing sugar beets in open piles increases the risk of hot spots forming, which could lead to microbial degradation of sugars.
Freezing also leads to the rupture of beet cell walls, making cell contents, including sugars, susceptible to leaching during thawing and washing. The thawing of sugar beets before processing requires large quantities of energy, which contributes to a less favorable greenhouse gas life cycle assessment.
Because of these storage problems, new long-term storage techniques are needed to preserve fermentable sugars from energy beets to allow for ethanol production throughout the year.
Since 2010, a research group in the Department of Agricultural and Biosystems Engineering at NDSU has studied the effectiveness of long-term storage techniques on the preservation of energy beet fermentable sugars.
Results indicate that concentrating beet juice through evaporation to produce a raw, thick beet juice and subsequently adjusting the pH of the juice are effective. The technique helped retain more than 99 percent of the fermentable sugars in the juice stored for at least six months at 23 degrees Celsius (approximately 73 degrees Fahrenheit).
During the study, the pH of the raw, thick juice was adjusted and controlled at alkaline and acidic levels to find the most effective ranges for sugar preservation.
Although the juice was stored successfully, future research will be directed toward determining conditions for high-efficiency fermentation of the juice with the highest sugar retention during storage.
The research was carried out by Juan Vargas-Ramirez, a graduate student pursuing a doctorate degree in the Department of Agricultural and Biosystems Engineering under the guidance of Dennis Wiesenborn, a professor. Other key project personnel include Darrin Haagenson, research specialist and Scott Pryor, associate professor.
This NDSU research is part of a larger effort initiated by BeetsAll Biofuel to envision beets as a potential feedstock for ethanol and other industrial uses.
BeetsAll Biofuel is a partnership between Green Vision Group and Heartland Renewable Energy. Other research sponsors and cooperators are the North Dakota Renewable Energy Council, North Dakota Agricultural Experiment Station and American Crystal Sugar.
More information about the NDSU research is available at http://www.beetsallbiofuel.com.