Brazil presents a unique model for the structural development of an energy sector: having made advances in technology for hydropower since the 19th century, which have dominated the country's energy matrix since the 1970s. During this period, several supply crises were faced. The most severe occurred in 2001, where general blackouts began to take place. This marked a turning point in the country, with the resumption of energy projects to guarantee the supply of energy to the population. Interestingly, the source of most of this energy remained the same: hydroelectricity (Gomes et al. 2002). The two biomes with the highest levels of species endangerment and fragmentation, the Cerrado and Amazon (Vedovato et al. 2016; de Oliveira et al. 2017), contain about 70% of the potentials for hydropower production (Ferreira et al. 2014). The negative impacts of the projects on the way of life of local communities on the river’s surroundings and nature are hard to avoid. Regardless of the Brazilian Environment Agency requiring specific conditions and limitations for the execution of such projects, the dam’s construction continued to defy these restrictions and create irreparable impacts on the environment and social areas (Fearnside 2009; Fearnside and Pueyo 2012; Abramovay 2014; Fuchs 2016; Winemiller et al. 2016). Moran et al. (2018) point that without considering the real social, environmental and cultural costs involved in the water dams construction, it cannot be considered a sustainable source of energy.
In the context of global climate change, Brazil has experienced precipitation and temperature shifts over recent years. Considering the lack of seasonality in Brazil, the impact of these shifts on electricity generation has been massive and has negatively impacted the population’s quality of life. More than 60% of the energy for the whole country comes from hydroelectricity, obtained from a mix of energy sources that makes the system highly vulnerable (chart 1) (EPE 2018). Without investment in the sector, the necessary amount of water, and without alternative sources of clean energy, the country is dependent more than ever on natural gas thermoelectric energy generation as an alternative to meet its demand (Welfle 2017). This makes the system expensive and harmful to the environment (Gomes 2014).
A relevant change in the energy sector requires investment, legislative and organizational changes, combining environmental considerations and a set of multi-criteria local planning and public participation (Haaren et al. 2012). According to Abramovay (2014), despite being responsible for a small share of the world’s energy matrix (3%), the increasing use of modern renewable energy sources (solar, wind, geothermal and modern biomass) lean towards to exponentially lower their costs and thus, make them more generally accessible. A distributed energy production system from renewable technologies would be able to provide a central source of renewable environmental-friendly energy.
Biomass energy is characterized by its diverse sorts of sources and conversion technologies for energy, presenting a relevant potential for supply through renewable energy. The term biomass includes plant material produced through photosynthesis and all its by-products, as cultivated crops, forest-wood, animal manures and organic matter (Vidal and da Hora 2011). A considerable amount of research has already been developed on the topic of cleaner, cheaper and accessible energy sources in a diverse sort of regions such as Peru (Lillo et al. 2015), Spain (Díaz-Cuevas et al. 2019), Italy (Palmas et al. 2012), Greece (Skoulou et al. 2011), Germany (Palmas et al. 2015), South Africa (Batidzirai et al. 2016) and Southern Asia (Bhattacharyya 2014), as some examples of the many researches present different methods to explore the best opportunities for renewable energy generation. Responsible for 8,2% of the energy supply in Brazil (EPE 2018), previous studies on biomass energy production conclude that it is an option that should be considered on the development of the country’s energy sector. In the Brazilian Atlas of Bioenergy (Coelho et al. 2012), a national-wide methodology was presented. There, it was considered residual energy production from agriculture and silviculture activities, liquid swine sewage and solid urban waste in sanitary landfills. Maps were used to present the results to each region of the country, considering different conversion efficiency scenarios.
The Rural Residues Energetic Inventory (EPE 2014) was produced by the Brazilian Energy Research Company in order to explore the potential as energy source from agriculture, agroindustry and livestock residues. A summary of different sources was presented, detailing the agriculture production and the estimation of its residues. A potential of 48 million toe for the agriculture and livestock waste was estimated, considering different conversion technologies, presented regarding the technical potential for biomethane and energy production.
Another example of biomass energy potential assessment in Brazil is the Biomass Residues as Energy Source to Improve Energy Access and Local Economic Activity in low HDI regions of Brazil and Colombia (BREA Project) (GBIO et al. 2015). In a cooperative effort between Brazilian and Colombian scientists, a complete data set on energy generation from residues was presented. The target of the study was to “develop a better knowledge of energy requirements for productive purposes among poor households in urban and rural areas of Brazil and Colombia (many of them in isolated regions), which could allow inputs for targeted policy interventions” (GBIO et al. 2015, p. 23). The methodology encompassed an assessment of different conversion technologies, potentials, policies, scenarios, and barriers to the development of bioenergy for 32 municipalities in the Brazilian Amazonian region.
Regarding other renewable energy sources, biomass energy requires needs the major area per produced energy unit (Blaschke et al. 2013a), and it could be related to a potential conflict with other land uses (Söderberg and Eckerberg 2013). Without considering careful planning, the competition between biomass energy, conservation, agriculture, and forestry is inevitable (Blaschke et al. 2013b). Concerning sustainability, any enterprise that seeks biomass as a source of power must guarantee the soil health, the biodiversity and water cycle, lowering the negative impacts in the long term.
One alternative for minimizing negative environmental impacts of biomass use and ensuring sustainability is to produce energy from cultivation residues, thereby bringing more opportunities to the local population. Several agricultural systems base their natural cycle on nutrient recycling, where part or certain residue of the main crop is left on the soil, to protect it physically from rain, sun, and wind and to nurture soil biota. The crop residue retention is, in fact, one of the three pillars of Conservation Agriculture (Hobbs et al. 2008; Sommer et al. 2018). This measure can avoid the necessity of the input of fertilizers and protect against soil degradation, as well as increase the carbon sequestration in the soil. However, some studies point out that there is no need to place all the residues on the soil. In some cases, a proportion can be removed without causing harm to the integrity of the soil (Dias et al. 2012; EPE 2014; Foelkel 2016).
In a country such as Brazil, where hydro energy represents not only the highest share in the energy matrix but also a fragile energy source in a climate change context, the assessment of alternatives that minimize environmental impacts, promote the sustainable development of the population, and guarantee the energy security should be seriously considered. In this paper, an estimation of the regional potential of energy production from biomass residues is assessed; recommendations from literature for how much residue could be removed without damaging the soil is also considered. This potential energy production is compared to the local energy demand. We aimed to answer the following questions:
According to Ribeiro and Rode (2016), the state of Minas Gerais in Brazil presents favorable characteristics for the development of biomass energy initiatives. The authors conducted an analysis with the objective of finding ideal regions to develop new biomass energy initiatives, considering the local demand, transmission lines, existing energy sources and environmental constraints (land use and environmental preservation factors). The state of Minas Gerais presented the higher potential for proving the sources to the development of a biomass energy initiative, respecting the environment fragilities and its regulations.
Minas Gerais gained importance during colonial times mainly from the wealth coming from its abundance of gold. With the exhaustion of these sources and the decline of the mining industry in the early nineteenth century, agriculture emerged as an important economic activity of the region. Considered by some authors as a period of stagnation and decay, the exhaustion of the gold mining activity left society more diverse, and one which demanded different agricultural products. This led to the structuring of a productive and commercial sector that aimed to meet these internal demands.
The industrial sector is the second largest in the Minas Gerais economy, accounting for about 29.5% of the state's GDP (IBGE 2017a), with the iron mining industry leading this economic sector. The state also stands out in the production of automobiles, steel products, cement, chemicals, and food. Minas Gerais also presents the third largest economy in Brazil, participating with approximately 8.7% of the Brazilian GDP, behind only the states of São Paulo and Rio de Janeiro (IBGE 2017a). The main agricultural goods produced are coffee, sugar, milk, various types of meats, soy, corn, and beans. In 2008, the exportation from the agribusiness reached US$ 5.9 billion, corresponding to 8.2% of Brazilian agribusiness exports that year (Bastos and Gomes 2011). The rural universe dominates the cultural identity of the population that, despite being known as miners (mineiros), has a historical and affective cultural relationship with the countryside culture (Souza 2013).
The Brazilian electrical distribution sector is mainly divided by state. Until the early 1990s, most of the states governments were the owners of the companies that provide the local operations on the energy distribution system (Tovar et al. 2010). This condition changed with the privatizations that came along to reduce the debt of a system that experienced rapid growth during the 1960s and 1970s and culminated in a profound crisis on the 1980s (Fagundes de Almeida and Queiroz Pinto Junior 2000; Lorenzo 2002; Tovar et al. 2010). The privatization wave did not reach the state of Minas Gerais, where the same company, CEMIG (Minas Gerais Energy Company), is responsible for the concessions of 96% of the state. CEMIG also figures as one of the few companies in the country that join the tasks of generation, distribution, transmission, and commercialization of energy (CEMIG 2012).
Considering the necessity of choosing a study area, the state unit appears as the most appropriate option, since besides having uniformity in the electric system, it also presents a political management unit, a factor that facilitates the creation and application of policies. The state of Minas Gerais has positive environmental and economic characteristics for the development of this study. Therefore, has been elected as the focus area of this paper
To analyze the self-sufficiency in sustainable bioenergy of a federative unit with the fourth largest territorial area, the second largest number of inhabitants and the largest number of municipalities in the country (IBGE 2017a) aims to bring light to the possible new paths that can guide the decision making on the direction of sustainable energy diversification in Brazilian energy matrix.