Arnaldo Walter

Techno-economic analysis of co-fired biomass integrated gasification/combined cycle systems with inclusion of economies of scale.

This work focuses on short-term application of biomass integrated gasification/combined cycle (BIG/CC) technology with co-firing of natural gas and biomass derived gas. Co-firing leads to higher efficiency and lower costs of BIG/CC technology. A full technical and economic analysis was carried out by integrating performance modeling from co-fired CC and scale effects over a wide range of capacities (20–300 MWe). The gasification technology is directly air-heated and the feedstock is sugar cane residue. Co-firing alleviates the need for de-rating gas turbines, which would reduce efficiency. It also allows combined cycles to be scaled up beyond the limits imposed by single vessel gasifiers. Mixing of LCV gas and natural gas can greatly improve the cost-effectiveness of power generated by BIG/CC. The cost of electricity (COE) for biomass reaches a minimum with 50% proportion of natural gas in the mixture. For proportions of natural gas higher than 60%, the biomass-based power in a co-firing scheme may become less cost-effective than a BIG/CC. A sensitivity analysis shows that if the energy input consists of 50% biomass, the most sensitive parameters—in decreasing order—are the efficiency, the capital costs of the combined cycle, the gas cleanup equipment and the biomass fuel costs.

Global market for bioethanol: historical trends and future prospects

Since the mid-1990s there has been a growing worldwide interest in alternative transport fuels, of which ethanol is among the most promising options. This interest has in recent years gathered pace, stimulated by high oil prices and the generally perceived view that this trend is likely to accentuate in the future. The need to reduce GHG emissions is also a fundamental reason for this interest. The focus of this paper is on fuel ethanol production from sugar and starches with emphasis on short-term issues and implications for the global market. Replacing 10-20 % of petrol with ethanol is a feasible and desired option. The international market in fuel ethanol is in its initial stage and its full development will require the diversification of production, in terms of both feedstocks and number of producing countries. Sustainable production should become a requirement for which certification seems to be a necessity, but should be defined to assure sustainability in a broad sense so that it does not impose additional barriers to trade; policies should be defined to induce market competitiveness and sustainable development.

Co-firing of natural gas and Biomass gas in biomass integrated gasification/combined cycle systems

This work aims to evaluate the co-firing of gas derived from biomass and natural gas in combined cycles. It is suggested that co-firing can solve some of the initial technological problems associated with the gas turbines of BIG-GT (Biomass Integrated Gasification/Gas Turbine) plants. De-rating is the simplest strategy that allows continuous gas turbine operation with low calorific value fuels, but it also reduces cycle power and efficiency. The proposed biomass gas is derived from sugar-cane residues and has a lower heating value of around to 6 MJ/Nm3. Modeling results show that if the natural gas content is higher than 35–50% (energy basis) no de-rating will be necessary. At these proportions, the efficiency of electricity generation is not substantially reduced vis-a-vis the reference case. Another important outcome of the modeling is that the peak in power that occurs for natural gas contents slightly higher than 50% in energy basis. Another advantage of co-firing is that it will entail only small hardware modifications to the gas turbines. A comparison is made between the co-firing strategy and the improvements likely to arise from retrofitting gas turbines for LCV fuels.

A case study of compact cogeneration using various fuels

A method for studying the technical and economic feasibility of absorption refrigeration systems in compact cogenerators is presented. The system studied consists of an internal combustion engine, an electric generator and a heat exchanger to recover residual heat from the refrigeration water and exhaust gases. As an application, a computer program simulates the cogeneration system in a building which already has 75 kW of installed electric power. The maximum electric and refrigeration demands are 45 kW and 76 kW respectively. This study simulates the system performance, utilizing diesel oil, sugar cane alcohol and natural gas as possible fuels.

Status and prospects for renewable energy using wood pellets from the southeastern United States

The ongoing debate about costs and benefits of wood‐pellet based bioenergy production in the southeastern United States (SE USA) requires an understanding of the science and context influencing market decisions associated with its sustainability. Production of pellets has garnered much attention as US exports have grown from negligible amounts in the early 2000s to 4.6 million metric tonnes in 2015. Currently, 98% of these pellet exports are shipped to Europe to displace coal in power plants. We ask, ‘How is the production of wood pellets in the SE USA affecting forest systems and the ecosystem services they provide?’ To address this question, we review current forest conditions and the status of the wood products industry, how pellet production affects ecosystem services and biodiversity, and what methods are in place to monitor changes and protect vulnerable systems. Scientific studies provide evidence that wood pellets in the SE USA are a fraction of total forestry operations and can be produced while maintaining or improving forest ecosystem services. Ecosystem services are protected by the requirement to utilize loggers trained to apply scientifically based best management practices in planning and implementing harvest for the export market. Bioenergy markets supplement incomes to private rural landholders and provide an incentive for forest management practices that simultaneously benefit water quality and wildlife and reduce risk of fire and insect outbreaks. Bioenergy also increases the value of forest land to landowners, thereby decreasing likelihood of conversion to nonforest uses. Monitoring and evaluation are essential to verify that regulations and good practices are achieving goals and to enable timely responses if problems arise. Conducting rigorous research to understand how conditions change in response to management choices requires baseline data, monitoring, and appropriate reference scenarios. Long‐term monitoring data on forest conditions should be publicly accessible and utilized to inform adaptive management.

Bioenergy and Biodiversity: Key Lessons from the Pan American Region.

Abstract Understanding how large-scale bioenergy production can affect biodiversity and ecosystems is important if society is to meet current and future sustainable development goals. A variety of bioenergy production systems have been established within different contexts throughout the Pan American region, with wide-ranging results in terms of documented and projected effects on biodiversity and ecosystems. The Pan American region is home to the majority of commercial bioenergy production and therefore the region offers a broad set of experiences and insights on both conflicts and opportunities for biodiversity and bioenergy. This paper synthesizes lessons learned focusing on experiences in Canada, the United States, and Brazil regarding the conflicts that can arise between bioenergy production and ecological conservation, and benefits that can be derived when bioenergy policies promote planning and more sustainable land-management systems. We propose a research agenda to address priority information gaps that are relevant to biodiversity concerns and related policy challenges in the Pan American region.

Potential impacts on local quality of life due to sugarcane expansion: a case study based on panel data analysis

Agribusiness participation in Brazil generates investments in rural infrastructure and employment, with direct effects on local quality of life. In this sense, government policies to support the production of ethanol from sugarcane and to promote bioelectricity from bagasse production have made Brazil a country of world leadership in this field. This paper reports an assessment of socioeconomic impacts due to sugarcane production in three regions in Brazil (Piracicaba, Presidente Prudente and Southwest Goiás). Local quality of life is defined as five dimensions: income and inequality, education, infrastructure, health and general development, analysed using panel data modelling, with variables that could explain differences in development due to local characteristics, including sugarcane activity. Presidente Prudente has the highest levels of progress in education, poverty, infrastructure and general development indicators. The models indicate that participation of sugarcane has positive impacts on the indicators of the microregion. In case of Piracicaba microregion, in two models (“L-Theil” and “Illiteracy rate”) indicators related with sugarcane sector are significant explanatory variables, contributing for better indicators. Finally, Southwest Goias—where sugarcane activity develops later—is the single microregion in which the adjusted models have no significant explanatory variables related to sugarcane sector.

Socio-Economic Impacts of Bioethanol from Sugarcane in Brazil

The impacts of sugarcane and ethanol production in Brazil are widely discussed in all steps of its production. The rapid expansion, the possible indirect land use changes, and the socio-economic impacts are of great concern for different stakeholders. As any economic activity, ethanol production and sugarcane cultivation have many positive and negative socio-economic impacts such as employment and income generation, health issues, and migration. In this chapter, three geographical levels of impacts and aspects are discussed for Brazil: national, with an overview of the country and the main macroeconomic impacts; regional, focusing on the Northeast region; and local level with two case studies, Pindorama mill and Sao Francisco mill.

Biomass energy in Brazil

Abstract Historically, biomass has provided a large share of Brazils energy supply. Despite its relevance, the success of some biomass programs has been constrained by short-term priorities to the detriment of long-term policies. The potential of biomass will only be accomplished if further activities are focused on sustainability in a broader sense. Arnaldo Walter, State University of Campinas, Brazil assesses bioenergy use in the country, highlighting past programs, activities and barriers to accomplishing future goals.

Biomass energy in Brazil: Past activities and perspectives

Abstract Historically, biomass has provided a large share of Brazils energy supply. Despite its relevance, the success of some biomass programs has been constrained by short-term priorities to the detriment of long-term policies. The potential of biomass will only be accomplished if further activities are focused on sustainability in a broader sense. Arnaldo Walter, State University of Campinas, Brazil assesses bioenergy use in the country, highlighting past programs, activities and barriers to accomplishing future goals.