## 1 Introduction
In order to obtain a competitive improvement in corn crops, thereby increasing the profits of growers, it is interesting to conduct the search for added value of the residues generated. One of the possible applications of these wastes is their energy use. Biomass from agricultural practices is mainly composed of hemicellulose (20-30%), cellulose (40-50%), lignin (10-25%) and other organic compounds [5]. Regarding corn stover, the percentages for the corncob waste are 35% hemicellulose, 45% cellulose and 15% lignin [6] and for corn stalk these percentages are 26.45% hemicellulose, 36.43% cellulose and 27.33% lignin [7], which indicates that corn stover could be used as biomass. Among the different thermal processes of biomass, pyrolysis and combustion two simple and direct processes for energy extraction from biomass are considered [8], as well as two essential procedures for the study and control of thermal processes that are developed during biomass conversion. For the study of thermal processes, thermogravimetric analysis (TG) is a basic tool, as it can assess the suitability of corn wastes as biofuels as well as it can determine the thermal process with the best performance. The main conclusions about the use of these residues as fuels can be inferred through the comparison of the results obtained with thermogravimetric results of other biomass samples currently used. Concerning the use of biomass, one of the ways to generate thermal energy is through pellet combustion, as it is considered an ecological fuel and classified as a biofuel with zero-net CO\({}_{2}\) emissions [9]. Its use can be industrial (for drying or steam production) or domestic (for heating or hot water production). Pellets show better characteristics than other biomass products like chips or briquettes, due to their higher density and consistent granulometry, which allows for automatic feeding in biomass boilers [10]. For this reason, pellet production is considered a promising and profitable market in Spain. So far, different studies about the energy use of corn residues have been published. [PERSON] et al. [7], [PERSON] et al. [8], and [PERSON] et al. [11] carried out the thermogravimetric analysis of corn stalk. Similarly, [PERSON] et al. [12], [PERSON] et al. [13] and [PERSON] et al. [14] carried out the thermogravimetric study of the corncob waste. Other articles have studied the pyrolysis of the complete corn stover [15; 16]. Concerning the separate study of this waste, [PERSON] et al. [17] carried out a thermogravimetric study of the pyrolysis of different parts of corn, such as corn stalk skins, corn stalk scores, corn bracts and corn leaves. Regarding thermogravimetric studies in combustion processes, different references were found, specifically about corn stalk [8] and corncob waste [18], separately. According to previous studies, a comparison of different wastes of corn is considered in the present article, such as the following: complete corn waste, stover, and different wastes that could be classified depending on the collection system of corn harvest (which generates stalk and corncob waste). So far, all the works carried out studied the wastes separately, according to their physical or morphological characteristics, whereas in this study, the separation of wastes depending on the collection system will prevail, so that the valorization of wastes can be easier without any additional complication during harvesting. Moreover, taking into account that ash content is one of the most important parameters to determine the quality of a biofuel after combustion [19]; the effect of the collection of corn residues on ash production was studied, as a negative effect is possible due to the contact of the wastes with the soil. This is the case of stover baling, where the waste is placed on the ground for a certain period of time before it is baled, dragging and adding some land in the final bale, which implies an increase in impurities in the residue.