• Energy Research

Abstract This study analyzed biogas production from the anaerobic digestion of Coffee Wastewater (CWW), in Brazil. Physicochemical analyzes of CWW were performed before and after biodigestion. Four biodigesters B1, B2, B3, B4 maintained at 37 °C ± 2 °C were connected to a gasometer. 1.35 L of CWW and 0.15 L of inoculum (sludge from an Upflow Anaerobic Sludge Blanket) were fed into biodigesters B3 and B4, resulting in a total substrate level of 1.5 L for each one. Biodigesters B1 and B2 were fed 1.5 L of CWW that was pH adjusted to 6–8 in all four biodigesters at the start of the biodigestion. Theoretical estimations were given for the biomethane potential (BMP) arising from the chemical oxygen demand (COD). Given the BMP values, economic feasibility analysis was performed for a biogas system implemented in a coffee roasting production system under three scenarios: I - BMP for CWW COD without inoculum; II - BMP for CWW COD with inoculum; and III - BMP for the minimum required level of CWW COD needed for the system to be economically viable. The highest methane content observed was 11.4% in B4, which had the highest relative methane production to removed volatile solids (17.31 LkgVS−1rem).

This study aimed to determine theoretically, the electrical optimum power of LFG using the maximum net benefit (MNB) methodology, and taking into consideration the economic, demographic, and regional aspects of the Inter municipal Consortium of the Micro-region of the High Sapucaí for Sanitary Landfill (CIMASAS, as acronym in Portuguese), that is located in the southern part of the State of Minas Gerais, Brazil. To this end, the prognosis for a 20-year period of household solid waste generation in this region was estimated and quantified based on population data, in order to estimate the LFG production and the energy that can be generated. From this point, the optimum power for thermal power plant (TPP) by LFG was determined. The results indicated that the landfill in this region could produce more 66,293,282m3CH4 (with maximum power of 997kW in 2036) in twenty years and that there would be no economic viability to generate energy from LFG, because the Net Present Value (NPV) would not be positive. The smallest population to that can achieve a minimum attractiveness rate (MAR) of 15% should be 3,700,000 inhabitants under the conditions studied. Considering the Brazilian National Electric Energy Agency (ANEEL) Resolutions, it would be 339,000 inhabitants with an installed power of 440kW. In addition, the outcome of the CIMASAS case-study demonstrated the applicability of MNB methodology for the determination of TPP optimum power.

Abstract Brazil is a country with a vast amount of water resources. However the country’s population is largely concentrated in areas where water access and availability is unfavorable. Water supply issues have grown more evident amongst recent shortages by generating grave consequences for public health, impacts on quality of life and hurdles to the country’s overall development. Desalination stands out as an alternative for diversification of the country’s water matrix to aid in solving these problems, given that this type of technology is capable of supplying water in the quantity and quality needed for human, industrial and agricultural consumption. However the costs and feasibility related to this technology within the Brazilian scenario are not known. The current study carried out cost analyses related to the implementation of Reverse Osmosis desalination for four scenarios, all with different importation rates, considering three energy sources. The study’s results demonstrated more viability in reverse osmosis implementation when using natural gas to generate electrical energy, given that the flow rate production costs for this technology was between 0.88 and 1.97 USD/m3. However, the importation scenario analysis indicated a great need for public incentives to create national desalination technology.

Abstract In Brazil, most Urban Solid Waste (USW) is disposed of in loosely controlled and low-quality dumps and landfills. One of the alternatives for improved management is incineration. This largely reduces the amount of waste in sanitary landfills, in turn enabling energy generation, which is encouraged by the Brazilian National Policy on Solid Waste (PNRS). In order to further the debate for the application of incineration plants in Brazil, the present study presents an energy and economic analysis. Calculations were carried out for different population groups in order to determine the minimum population and the respective waste generation to make an incineration plant viable. The country’s energy potential was also estimated as a function of the energy tariff. The results show that the energy produced through incineration can provide power to an average of 15% of the waste generating population. The viable energy potential in the country was confirmed only for scenarios with higher energy sales tariffs than those currently applied on the Brazilian market. These results indicate the need for government intervention in order to make this technology economically viable, which would in turn reduce inadequate waste disposal throughout the country.

Abstract An anaerobic wastewater treatment generates at the end of its process an anaerobic biomass, also known as anaerobic sludge, and a major sub product, the biogas, composed mainly by methane (CH4) and carbonic gas (CO2). The biogas needs to be collected in order to be flared or used in another process, especially because it cannot be released directly into the atmosphere due to methane gas and its high global warming potential. Nevertheless, when this gas is burnt, an energy vector for micro generation is discarded. In the present work was designed a thermal power plant using the biogas produced in an anaerobic wastewater treatment plant (WWTP) through an implementation methodology that considers the population growth according to a southeast ordinary Brazilian city. The energy production potential, avoided CO2 emissions due to the biogas burnt and the possibility of using this energy to supply the WWTP’s internal demand consumption were analyzed, as well as the project’s economic viability and the arising benefits from carbon credits, calculated in three scenarios. The data of calculus were based on the Brazilian sales tariffs obtained from Brazilian National Electric Energy Agency – ANEEL, where: i) T1 = 64.9 [US$/MWh] (average tariff on Brazilian energy auction A-5); ii) T2 = 86.47 [US$/MWh] (average tariff for thermal power plants in the same auction), and iii) the third scenario, in which the energy produced would be consumed by the WWTP’s internal demand. The economic viability was only achieved in second and third scenarios, being intensified in the scenario that WWTP’s internal demand is supplied using the energy generated in the biogas plant.

Abstract This article presents the main regulatory changes that occurred in the Brazilian power sector in 2009, along with the impacts these changes caused on the market, especially related to small hydropower (

Abstract Energy recovery from waste is one of the strategies that can assist the expansion of renewable energy in Brazil. Among the various types of waste, vinasse, which is a residue that contains a high organic load, originates from the sugarcane industry, which is a very important industry for the Brazilian economy. Due to high levels of sugarcane harvesting in the country and the production of large amounts of ethanol, vinasse is produced at high levels in Brazil. In this context, this paper presents an energy analysis of the avoided carbon dioxide emissions and economic viability associated with the combustion of biogas produced by the anaerobic digestion of the vinasse that results from the use of sugar cane planted in Brazil. Based on the literature review, data related to the process of biogas production from anaerobic digestion of the vinasse were collected and used for the calculation of the energy potential associated. The results show that to achieve economic viability for the use of this waste for energy, the following plantation areas would be required, considering their processed sugarcane equivalents: 14,580 ha (if considering the processing of sugarcane in attached plants), and 6000 ha (if considering the processing of sugarcane in autonomous plants). The total energy potential of this use may reach 3.26 TWh e /y, which represents 0.52% of all domestic energy consumption in 2014. The potential to avoid emissions from the same use could reach 1.9 Mt CO 2 /y, which is approximately 2.1% of the emissions for the whole industry in Brazil in 2014. These results demonstrate the environmental and energy benefits that can be obtained via power generation from biogas produced by the anaerobic digestion of vinasse and highlight the need to include the use of such residue for energy in expansion plans for the Brazilian energy matrix.