# Estimation of the Energy Consumption of the Rice and Corn Drying Process in the Equatorial Zone
## 1 Introduction
From the previous evidence, it is clear that corn and rice are vital products for Ecuador's food sovereignty; therefore, it is necessary to analyse the entire production chain, including energy use. In Ecuador, drying processes at the agroindustrial level mainly use liquefied petroleum gas (LPG) and diesel fuel as an energy source. However, the cost of both energy sources depends on the international market. Locally, the policy of subsidies about fuels makes LPG for domestic use the most widely used in the drying industry, since its price is 0.107 $/kg [16]; it is lower compared to the LPG of agricultural use which price is 0.188 $/kg or diesel with a price of 1781$/gallon [17]. The situation described, concerning costs, stimulate the consumption of LPG for domestic use in most agroindustrial processes, which directly affects economic resources and targeting of subsidies. This problem forced the Ecuadorian State to issue Ministerial Agreement No. 69 in 2007, which aimed to regularize the use of LPG by users of the agroindustrial sector dedicated to grain drying (corn, rice, and soybean), establishing the obligation to install and use centralized facilities or systems for receiving LPG. To date, the regulation of LPG use has not yet been achieved, mainly due to technical problems and ignorance of the energy consumption during the drying processes. From the energy point of view, another variable of interest is electricity consumption, which, in the Ecuadorian case, is regulated using a tariff sheet issued by the Electricity Regulation and Control Agency, classifying the consumer as residential, commercial, and industrial. In the particular case of residential consumers, the application of the Dignity Rate Subsidy is provided when monthly energy consumption is less than 110 kWh-month in the distribution companies of the Highland Region and 130 kWh-month in those of the Coast/Amazon/Galapagos Region [18], with an average cost of 4 \(\upepsilon\)/kWh, [19] compared to the invoiced cost of the residential consumer, which is 10.28 \(\upepsilon\)/kWh. On the other hand, consumers of the industrial category have a billing cost that depends on its consumption range and the rate of the voltage level they use; in practice, it is an average value of 7.28 \(\upepsilon\)/kWh. In summary, in Ecuador, the cost of electricity service for the year 2019 reached an average price of 9 \(\upepsilon\)/kWh [20]. It is appropriate to emphasize that, in the Ecuadorian case, in addition to explicit consumption subsidies, there are subsidies to the implicit electricity derived from the hidden costs of electricity, related, for example, to the fact that public generation companies exclude capital costs from calculating the cost of energy, transmission, and distribution [21]. In the particular case of Ecuador, there is little information on energy consumption in drying processes. In addition, there is no assessment between the existing drying technology and its association with the designs and construction of dryers in agroindustrial plants or collection centres of cereals on the Ecuadorian coast [22]. Moreover, most dryers in the agroindustrial sector are located in the provinces of Guayas and Los Rios, which corresponds to the climatic floor of \"Tropical Mega thermic semi-humid,\" according to the classification established by [PERSON] in 1983 [12]. Most equipment is of the artisanal or semiartsian type; therefore, there are many problems during drying due to not being able to control the temperature and wind speed of the hot gas towards the drying chamber (nonuniform drying). In addition, due to its poorly designed and constructed equipment consumes an unnecessary amount of fuel for its operation [23]. The majority of the rice collection centres (piling centres) are located in the cantons of Daule, Salitre, and Santa Lucia, with more than 200 rice hullers. Regarding to corn, its collection centres are located in Los Rios province, especially in Ventanas canton, which is considered a corn city due to its agricultural nature [24].