**2. Materials and methods**

### **2.1 Area of study**

*Biomass for Bioenergy - Recent Trends and Future Challenges*

emissions of greenhouse gases (EGGs) [6].

globally [8].

electricity [11].

of 17,500 kJ kg<sup>−</sup><sup>1</sup>

tons [16].

emissions [17, 19].

(G/CC), respectively [2].

residue producers [14].

Renewable energy offers environmental benefits and increases the standard of living for various populations, diversifies the energy matrix, improves the infrastructure, promotes technology transfer, and provides other positive effects [4, 5]. Biofuels are nonconventional renewable energy sources (NCRECs) that may replace fossil fuels, lowering the dependence on international markets and the atmospheric

Chile promised, in 2010, to reduce emissions by 20% below the 2020 projection [7]; however, according to current trends, an increase of 360% is projected in carbon dioxide (CO2) emissions in electricity generation and transportation. The aforementioned items currently represent 0.3% of the total emissions

Firewood and biofuels are the second source of energy for Chile. They are entirely produced within the country, representing 28.9% of the primary energy matrix in 2013 [9]. Here, 36% of the national population is concentrated between the O'Higgins and Aysén Regions, with 74% of these homes consuming firewood or its derivatives [10] for heating or cooking systems. Biofuel is used for self-produced

The residual biomass from agricultural activities has an average caloric power

concentrated in the central south area of the country, particularly in the regions of Araucanía (29.3%) and Libertador Bernardo O'Higgins (19.8%) as the main cereal

Wheat is the main cereal produced in Chile, representing 32.9% of the planted agricultural surface during the 2016/2017 agricultural season [15]. The Araucanía Region is the main wheat production region in the country. During the 2016/2017 agricultural season, 42.0% of the total surface area of planted wheat was concentrated here, yielding a production of approximately 597,835

Román-Figueroa et al. [2] determined that, in the Araucanía Region, 50% of the production of wheat residuals was concentrated in 23 (of 299) census districts, while 10 of these districts produced 27.8% of the residues. The majority was produced in the central valley of the region, specifically in the province of Malleco, which has a regional coverage of 60,800 ha [2]. Currently, the agricultural residue is burnt [17, 18], which causes environmental problems owing to the emission of EGGs, as well as public health problems owing to particulate matter

Electricity production from agricultural residue biomass has been widely studied and recommended, owing to the low production costs, high conversion efficiency, and environmental benefits because it is carbon neutral [20, 21]. Singh [21] determined, in the Punjab, India region, production of between 2375 and 2937 MWel was possible depending on the efficiency of the conversion plant, with more than 22,000 million tons of residue. In the Araucanía Region, a 5.0 MWth plant and 27,000 tons of residue, between 3.17 MWel and 4.89 MWel, can be produced using fluidized bed combustion technology with a generation turbine (C/ST) and gasification of the fluidized bed followed by a combined cycle of gas and vapor

Various studies have determined the optimal location of a biomass-based energy production plant using geographic information systems (GIS) [21–25]. With GIS, evaluation using different attributes and maps to determine the optimal energy production plant location is feasible, [23, 25]. A multi-criteria analysis (MCA) evaluates, using different criteria or factors, a group of opposed real alternatives, considering different development visions and objectives [25]. Therefore, an

[12] and is underused in Chile [2, 13]. Cereal production residue is

**144**

The area of study was the Araucanía Region, located between 37°35′ and 39°37′ southern latitude and from 70°50′ western longitude to the Pacific Ocean, an area of 31,842 km<sup>2</sup> (**Figure 1**). The study was realized at a district level

**Figure 1.** *Study area of Araucanía region, Chile, on a district scale.*

according to the census boundaries determined by the National Institute of Statistics [26].
