919 resultados para gas production
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Three tropical legumes, namely Leucaena leucocephala, Sesbania sesban and Cajanus cajan, were subjected to chemical analysis plus in vitro, in situ and in vivo evaluations. Three different assays were used to determine total tannins: adsorption to polyvinyl pyrrolidine (PVPP-tannins), radial diffusion (RD-tannins) and protein precipitation capacity (BSA-tannins). Total phenols, total tannins and condensed tannins were highest for Sesbania. RD-tannins were correlated with total phenols (r(2) = 0.93), PVPP-tannins (r(2) = 0.92) and condensed tannins (r(2) = 0.99). The protein precipitation capacity of Sesbania, Leucaena and Cajanus were 25.9, 6.13 and 4.05 mu g BSA/g DM, respectively.Gas production at 24h was negatively correlated with total phenols (r(2) = 0.99), PVPP-tannins (r(2) = 0.99) and condensed tannins (r(2) = 0.91). The RD-, PVPP-tannins and the response to polyethylene glycol (PEG) in the gas production assay appeared to be useful as a first screen for tannins.In situ degradability did not reflect any adverse effects of tannins. However, in vivo experiments showed that the apparent DM digestibility of Sesbania and Leucaena was lower than the basal diet. The apparent protein digestibility was lower for all legumes compared to the basal diet. Most treatments caused a negative nitrogen balance. The problems associated with browse feeding were not only related to tannin contents, other factors such as inherently poor digestibility and low energy intake may also have lead to the poor animal performance on these diets. We propose, given the limitations of current tannin assays, that it is not possible to predict beneficial or harmful nutritional effects from total tannin concentrations per se. (C) 2004 Elsevier B.V. All rights reserved.
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Fibre, crude protein and tannin concentrations were measured in browse species from the semi-arid region of Northeast Brazil during the dry and wet seasons. The effects of oven-, sun- and shade-drying and of urea treatment were also determined. Crude protein (CP) content varied from 103 to 161 g/kg dry matter (DM) and the browses had similar CP content in the two seasons (during 2002) (102-161 and 107-153 g/kg DM in the wet and dry seasons, respectively). Total tannin concentrations ranged from 13 to 201 g/kg DM amongst the browses and were higher in the dry season. A 30-d treatment with urea reduced extractable tannins significantly (P < 0.05). The urea treatment was also most effective at reducing the in vitro effects of tannins compared to the other drying treatments. This was demonstrated by measuring the effect of polyethylene glycol (PEG) on gas production. Addition of PEG increased gas production of oven- (81.4%), sun- (78.5%) and shade-dried (76.7%) samples much more compared to urea treated samples (10.9%). (c) 2005 Elsevier B.V. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The energy sector is a dominant one in Trinidad and Tobago and it plays an important role in the twin-island republic‟s economy. In 2008, the share of the energy sector in gross domestic product (GDP) amounted to approximately 48% while contributing 57% to total Government revenue. In that same year, the sector‟s share of merchandise exports was 88%, made up mainly of refined oil products including petroleum, liquefied natural gas (LNG), and natural gas liquids (Central Bank of Trinidad and Tobago, 2009). Trinidad and Tobago is the main exporter of oil in the Caribbean region and the main producer of liquefied natural gas in Latin America and the Caribbean. The role of the country‟s energy sector is, therefore, not limited to serving as the engine of growth for the national economy but also includes providing energy security for the small island developing States of the Caribbean. However, with its hydrocarbon-based economy, Trinidad and Tobago is ranked seventh in the world in terms of carbon dioxide (CO2) emissions per capita, producing an estimated 40 million tonnes of CO2 annually. Almost 90% of these CO2 emissions are attributed directly to the energy sector through petrochemical production (56%), power generation (30%) and flaring (3%). Trinidad and Tobago is a ratified signatory to the United Nations Framework Convention on Climate Change and the Kyoto Protocol. Although, as a non-Annex 1 country, Trinidad and Tobago is not required to cut its greenhouse gas emissions under the Protocol, it is currently finalizing a climate change policy document as well as a national energy policy with specific strategies to address climate change. The present study complements the climate change policy document by providing an economic analysis of the impact that climate change could have on the energy sector in Trinidad and Tobago under the Intergovernmental Panel on Climate Change alternative climate scenarios (A2 and B2) as compared to a baseline situation of no climate change. Results of analyses indicate that, in the short-run, climate change, represented by change in temperature, is not a significant determinant of domestic consumption of energy, electricity in particular, in Trinidad and Tobago. With energy prices subsidized domestically and fixed for years at a time, energy price does not play a role in determining electricity demand. Economic growth, as indicated by Gross Domestic Product (GDP), is the single major determinant of electricity consumption in the short-run. In the long-run, temperature, GDP, and patterns of electricity use, jointly determine electricity consumption. Variations in average annual temperature due to climate change for the A2 scenario are expected to lead to an increase in electricity consumption per capita, equivalent to an annual increase of 1.07% over the 2011 baseline value of electricity consumption per capita. Under the B2 scenario, the average annual increase in electricity consumption per capita over the 2011 baseline value is expected to be 1.01%. The estimated economic impact of climate change on electricity consumption for the period 2011-2050 is valued at US$ 142.88 million under the A2 scenario and US$ 134.83million under the B2 scenario. These economic impact estimates are equivalent to a loss of 0.737% of 2009 GDP under the A2 climate scenario and a loss of 0.695% of 2009 GDP under the B2 scenario. On the energy supply side, sea level rise and storm surges present significant risks to oil installations and infrastructure at the Petroleum Company of Trinidad and Tobago (PETROTRIN) Pointe-a-Pierre facilities (Singh and El Fouladi, 2006). However, data limitations do not permit the conduct of an economic analysis of the impact of projected sea level rise on oil and gas production.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Zootecnia - FCAV
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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A gaseificação é uma conversão termoquímica da biomassa em gás combustível, que pode ser usado como combustível em motores de combustão interna ou como gás de síntese para a indústria química. Para checar o desempenho de um gaseificador temos de quantificar a energia contida no gás produzido e a quantidade de carbono convertido por meio dos cálculos de eficiência energética e de conversão de carbono através dos dados obtidos experimentalmente. A eficiência energética é uma relação entre os fluxos de gás e biomassa e de suas respectivas quantidades de energia, no mesmo sentido, a conversão de carbono é a quantidade de compostos carbonáceos presentes no gás convertido a partir da quantidade de carbono presente na composição da biomassa. O presente documento avalia a eficiência energética e de carbono na conversão de um protótipo de um gaseificador indiano do tipo downdraft produzido por uma empresa local (Floragás). Os parâmetros nominais do gaseificador são: capacidade de produção de gás de 45 kWt, consumo de biomassa (caroço de açaí) de 15 kg/h. As dimensões do gaseificador são: DI 150 mm e altura de 2000 mm). A eficiência energética e a taxa de conversão de carbono foram quantificados, a queda de pressão devido ao leito do reator e a temperatura dos gases também foram medidos na saída do reator e também, a concentração de alcatrão, partículas e gases não condensáveis (CO, CO2, CH4, SO2, N2 e NOx) nos gases de combustão após a sistema de limpeza.
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Pós-graduação em Zootecnia - FCAV