A Principal Component Analysis in Switchgrass Chemical Composition
Aboytes, M., K. Castillo, T. E. Yu, C. Boyer, B. C. English, J. A. Larson, L. M. Kline, and N. Labbe.  2016.  Energies, 9, 913.

In recent years, bioenergy has become a promising renewable energy source that can potentially reduce the greenhouse emissions and generate economic growth in rural areas. Gaining understanding and controlling biomass chemical composition contributes to an efficient biofuel generation. This paper presents a principal component analysis (PCA) that shows the influence and relevance of selected controllable factors over the chemical composition of switchgrass and, therefore, in the generation of biofuels. The study introduces the following factors: (1) storage days, (2) particle size, (3) wrap type, and (4) weight of the bale. Results show that all the aforementioned factors have an influence in the chemical composition. The number of days that bales have been stored was the most significant factor regarding changes in chemical components due to its effect over principal component 1 and 2 (PC1 and PC2, approx. 80% of the total variance). The storage days are followed by the particle size, the weight of the bale and the type of wrap utilized to enclose the bale. An increment in the number of days (from 75‐150 days to 225 days) in storage decrease the percentage 25 of carbohydrates by ‐1.03% while content of ash increase by 6.56%.