URBANA - The weather in Illinois affects everything, including current research in the development of biomass as an energy source. Miscanthus is one of the promising agricultural crops being evaluated as a potential biomass feedstock alternative. Recent agronomy and crop science studies suggest that winter is the optimal time to harvest Miscanthus, so researchers at the University of Illinois have studied the impact weather can have on feedstock production and harvest, as well as subsequent storage and supply activities.
“Winter in Illinois can be very difficult,” said Yogendra Shastri, a visiting research assistant professor in the Department of Agricultural and Biological Engineering (ABE) and member of the Energy Biosciences Institute in the Institute for Genomic Biology, “and you cannot ignore its impact on the feedstock harvest system.
“In the past, we have developed BioFeed, a mathematical model that determines the best production system for energy crops and provides decision support to farmers,” Shastri continued. “That includes things like what type of harvester should be used, where the biomass should be stored, and how big the storage facility should be. Now, weather effects are incorporated in BioFeed, with the inclusion of the probability of working day (PWD) parameter in the model.”
The PWD defines the fraction of days in a specific period (such as two weeks) that are suitable for field operations, and its value depends on a number of weather-related parameters, such as rainfall, snow depth, soil temperature, and soil moisture content. Researchers found that the average value of PWD for Illinois in winter is about 30 percent. Model simulations were conducted for Miscanthus for intended biorefinery capacity of 3000 megagrams per day (about 90 million gallons per year of ethanol). The impact on total cost and farm machinery requirements was then quantified.
“We found that if you assume every day is available for field work, lower PWD value could increase your actual costs by as much as 38 percent. You lose biomass, and that has an impact on all the subsequent operations,” said Shastri. “A way to compensate for that is to buy more machinery, so that you are still able to complete all the operations in the limited amount of time you have. However, this leads to about 34 percent more investment in machinery. So it’s a trade-off. However, we have recommended that instead of starting the harvest in January, begin in late October or early November. That will have a significant impact on reducing the cost.” Researchers have also found that switchgrass, another candidate energy crop, is not impacted as much by weather since it is harvested in late fall when the weather is much more conducive.