Avaliação do potencial energético em biomassa do Alto Alentejo

Em Portugal, a opção de promover a utilização de fontes de energia renovável arrasta consigo benefícios não apenas em termos da prevenção da diminuição dos recursos fósseis e redução da dependência energética, mas também ao nível do desenvolvimento estratégico das economias regionais. A valorização energética dos resíduos orgânicos associados à biomassa é, deste modo, um assunto de grande relevância nos dias de hoje, em especial nas comunidades ditas rurais. O presente trabalho faz uma avaliação do potencial de produção de resíduos biomássicos de origem agro-florestal no Alto Alentejo, numa perspectiva de valorização energética da biomassa por processos de conversão termoquímicos. A metodologia é centrada no recurso, do tipo bottom-up, e foca-se na estimativa do potencial técnico de produção de biomassa na região com base em informação cartográfica e estatística actual. Os resultados são integrados num Sistema de Informação Geográfica (SIG) e a informação obtida georreferenciada. As componentes do potencial em biomassa analisadas são: área efectiva (em ha), disponibilidade de biomassa (em ton secas/ha) e potencial energético (em MWhe/ano). O potencial de resíduos agrícolas e florestais do Alto Alentejo estimou-se em 4.000 ton secas/ano e de 40.000 ton secas/ano, respetivamente. Esta quantidade de biomassa possui um potencial energético de 43.700 MWhe/ano, equivalente a 100% da energia elétrica consumida nos municípios de Alter do Chão, Crato e Sousel no ano de 2010. O sobreiro, a azinheira e o eucalipto possuem o maior potencial na floresta; na actividade agrícola, a vegetação herbácea e o olival constituem os resíduos mais importantes. Realiza-se uma análise primária à viabilidade da localização e das características de uma central termoeléctrica de 10MVA na região, tendo-se concluído que a biomassa disponível não é suficiente para abastecer a instalação energética prevista. Soluções alternativas e espécies mais representativas em termos de exploração foram discutidas, tendo-se verificado que a opção de aproveitamento mais promissora para a região é a combustão ou gaseificação de resíduos em instalações descentralizadas de pequena dimensão.In Portugal, the option of promoting the use of renewable energy sources yields benefits not only at preventing the depletion of fossil fuels and energy dependency on external sources, but also in terms of strategic development of regional economies. The energy valorization of the organic residues linked with biomass is, therefore, a very significant topic nowadays, especially on rural communities. This work assesses the potential for the generation of biomass residues, both from forest and agricultural sources, in a region of Portugal (Alto Alentejo), with a perspective of energy valorization of the biomass by means of thermochemical conversion processes. The model uses a bottom-up and resource-focused approach, estimating the technical potential of bioenergy in the region based on current cartographic and statistical data. The results are integrated into a Geographical Information System (GIS) from which georeferenced information is obtained. The analyzed components related with the biomass potential are: effective area (in ha), biomass availability (in dry ton/ha) and energy potential (in MWhe/year). The potential of agricultural and forest residues in Alto Alentejo is estimated at 4000 dry ton/year and 40000 dry ton/year, respectively. This amount of biomass corresponds to an energy potencial of 43700 MWhe/year, equivalent to 100% of the combined consumption of electricity in Alter do Chão, Crato and Sousel municipalities in 2010. Cork oak, holm oak and eucalyptus have the highest forest potentials; in terms of agricultural activity, herbaceous vegetation and olive yards are the most important residues. A primary analysis is done on the suitability of the location and characteristics of a 10MVA biomass power plant in the region and it was concluded that not enough biomass is available to supply the energy facility. Alternative solutions and the most representative species exploitable in the territory are also discussed and it was found that the most promising option for the region is combustion or gasification of residues in small scale facilities

A Heuristic Solution Based on Clarke & Wright's Savings Algorithm for the Optimization of Sludge Hauling: the case of a Portuguese company

Sewage sludge originating from wastewater treatment plants (WWTPs) can be a major cause of environmental pollution and their appropriate management should be viewed as a priority. A critical aspect in sludge management practices is route optimization since significant costs are associated with the transportation of waste. In this work, we propose a heuristic solution based on Clarke-Wright savings method for the sludge collection problem of a Portuguese company within a perspective of reducing collection costs (transportation) and negative impacts on the environment. Two case studies were considered in the methodology: the first one focused on the comparison between the general weekly collection plan presently used by the company and the solution generated by CW algorithm (Case Study A); the second one explored a new hypothetical scenario centered on the expansion of the company’s activities (Case Study B). In general, the application of CW method led to a decrease in traveled distances and transportation costs, as well as carbon dioxide emissions. Specifically, with the adoption of the optimized plan in Case Study A we found that a single vehicle (instead of three) would be capable of performing sludge hauling operations in a given week leading to total weekly savings of 346 km, representing a decrease of almost 40% for both cost and pollutant emissions. Regarding Case Study B, the model suggests that for about 76% of the initial cost, the company would be capable of attending twice the number of customers, i.e., via route optimization, it is possible to expand their client portfolio while still creating savings. Moreover, a sensitivity analysis (SA) was carried out in order to check the robustness of results when undergoing changes in the input parameters. We found that vehicle capacity and fuel price are two important factors in route optimization with model results greatly influenced by changes in both parameters.info:eu-repo/semantics/publishedVersio

Market Opportunities in Portugal for the Water-and-Waste Sector Using Sludge Gasification

The water-and-waste sector has shown a marked interest in innovative management practices for dewatered sludge. The need to manage increased sludge volumes at rising disposal costs, coupled with the recognition of the potential for on-site energy production, have been the key drivers for this recent appeal. With the current political view supporting the development of a renewable-gas industry in Portugal, renewable gases are considered an attractive solution for dewatered-sludge valorization. Moreover, investment in renewable-gas supply chains would help the industry to mature to a level at which the technology and market are rapidly established. Recognizing this interest, dewatered-sludge gasification was selected as a possible valorization pathway, with the potential for hydrogen and bio-SNG production, as well as decentralized heat and power. This document identifies the market opportunities for the establishment of sewage-sludge gasification in Portugal. The analysis starts with a brief overview of the Portuguese water-and-waste sector, and a description of the current status of the renewable-gas markets. Finally, the dewatered-sludge amounts are quantified, and the potential for energy and renewable-gas production is estimated to support the interest in wastewater management in advanced processes, and to pave the way for future feasibility studies

Biochar: Production, Applications, and Market Prospects in Portugal

Biochar produced during the thermochemical decomposition of biomass is an environmentally friendly replacement for different carbon materials and can be used for carbon sequestration to mitigate climate change. In this paper, current biochar production processes and top market applications are reviewed, as well as emerging biochar uses gaining momentum in the market. Various application fields of biochar, including agricultural applications (e.g., soil conditioning), adsorption (for soil and water pollutants), carbon sequestration, catalysis, or incorporation into composites or construction materials, are also presented and discussed. According to this literature overview, slow pyrolysis is the preferred process for biochar production, whereas agricultural applications (for soil conditioning and fertilization) are the most studied and market-ready solutions for biochar use. The Alentejo region (Portugal) shows tremendous potential to be a major player in the developing biochar market considering feedstock availability and large areas for biochar agricultural application. Biochar’s production potential and possible benefits were also estimated for this Portuguese region, proving that agricultural application can effectively lead to many environmental, economic, and social gains

Market Opportunities in Portugal for the Water-and-Waste Sector Using Sludge Gasification

The water-and-waste sector has shown a marked interest in innovative management practices for dewatered sludge. The need to manage increased sludge volumes at rising disposal costs, coupled with the recognition of the potential for on-site energy production, have been the key drivers for this recent appeal. With the current political view supporting the development of a renewable-gas industry in Portugal, renewable gases are considered an attractive solution for dewatered-sludge valorization. Moreover, investment in renewable-gas supply chains would help the industry to mature to a level at which the technology and market are rapidly established. Recognizing this interest, dewatered-sludge gasification was selected as a possible valorization pathway, with the potential for hydrogen and bio-SNG production, as well as decentralized heat and power. This document identifies the market opportunities for the establishment of sewage-sludge gasification in Portugal. The analysis starts with a brief overview of the Portuguese water-and-waste sector, and a description of the current status of the renewable-gas markets. Finally, the dewatered-sludge amounts are quantified, and the potential for energy and renewable-gas production is estimated to support the interest in wastewater management in advanced processes, and to pave the way for future feasibility studies

Costs of Gasification Technologies for Energy and Fuel Production: Overview, Analysis, and Numerical Estimation

During recent years, gasification technology has gained a high potential and attractiveness to convert biomass and other solid wastes into a valuable syngas for energy production or synthesis of new biofuels. The implementation of real gasification facilities implies a good insight of all expenses that are involved, namely investments required in equipment during the project and construction phases (capital expenditures, CapEx) and costs linked to the operation of the plant, or periodic maintenance interventions (operational expenditures, OpEx) or costs related to operations required for an efficient and sustainable performance of a gasification plant (e.g., feedstock pre-treatment and management of by-products). Knowledge of these economic parameters and their corresponding trends over time may help decision-makers to make adequate choices regarding the eligible technologies and to perform comparisons with other conventional scenarios. The present work aims to provide an overview on CapEx associated with gasification technologies devoted to convert biomass or solid waste sources, with a view of reducing the carbon footprint during energy generation or production of new energy carriers. In addition, an analysis of technology cost trends over time using regression methods is also presented, as well as an evaluation of specific capital investments according to the amount of output products generated for different gasification facilities. The novelty of this work is focused on an analysis of CapEx of existing gasification technologies to obtain distinct products (energy and fuels), and to determine mathematical correlations relating technology costs with time and product output. For these purposes, a survey of data and categorization of gasification plants based on the final products was made, and mathematical regression methods were used to obtain the correlations, with a statistical analysis (coefficient of determination) for validation. Specific investments on liquid biofuel production plants exhibited the highest decreasing trend over time, while electricity production became the least attractive solution. Linear correlations of specific investment versus time fitted better for electricity production plants (R2 = 0.67), while those relating the product output were better for liquid biofuel plants through exponential regressions (R2 = 0.65)