Validation of the Deardorff model for estimating energy balance components for a sugarcane crop

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Energy balance for biodiesel production by the castor bean crop (Ricinus communis L.)

The castor bean crop (Ricinus communis L.) has acquired prestige due to industries interest in the oil quality and recently for new sources of energy demand. The experiment that served as basis for the data used in this study was conducted at the Lageado Experimental Farm, in Botucatu - SP, 2008. This study aimed to avaluate the crop viability through energy balance and energy efficiency since the implantation until biodiesel production using parameters of consumption in operational management for installation and maintenance of culture harvest and oil production. The soil management operations, sow and harvest consumed the total of 266.20 MJ ha(-1), gathering with the fertilizers, pesticides, fuels, lubricants, labor, seed and industrial processing totaled 56,808 MJ ha(-1) of energy inputs. The energy production was 72,814.00 MJ ha(-1). The industry still lacks studies thal would contribution data collection and more specific energy coefficients. The castor beans cultivation was considered efficient allowing again of 15983.44 MJ ha(-1) equivalent to about 415 liters of diesel oil.

Energy balance optimization of sugarcane crop residual biomass

This work presents a mathematical model for helping mills choose sugarcane varieties for planting. It maximizes crop residual biomass energy balance by considering the difference between generated and consumed energy in the process of transferring this biomass from the field to the processing center; it takes into account enterprise demand restrictions and cane planting area. For this full zero-one linear programming techniques were proposed. The model is viable for choosing sugarcane varieties that would benefit sugarcane production and industrial systems, by reducing crop residue and increasing final energy production. (c) 2006 Published by Elsevier Ltd.

Development and energy balance of sugarcane in the norte fluminense, Brazil

The growing concern for renewable and cleaner energy sources has increased the demand for biofuels, pointing out the ethanol from sugarcane. The aim of this study was quantify the partition of energy balance components and monitor the physiological development indexes of the sugarcane, relating them to water availability conditions of climate and soil in Campos dos Goytacazes, Norte Fluminense, Brazil. To this end, a micrometeorological station was settled in an area of 13 ha in commercial cultivation. The culture was regularly monitored at 85, 102, 128, 149, 174, 194, 215, 235, 255 and 280 days after cutting (DAC). The variations in water availability directly influenced the rates of crop growth and energy balance. Under the conditions studied most of the available energy (53%) was consumed by the latent heat flux.

Application of landsat images for quantifying the energy balance under conditions of land use changes in the semi-arid region of Brazil

In the Nilo Coelho irrigation scheme, Brazil, the natural vegetation has been replaced by irrigated agriculture, bringing importance for the quantification of the effects on the energy exchanges between the mixed vegetated surfaces and the lower atmosphere. Landsat satellite images and agro-meteorological stations from 1992 to 2011 were used together, for modelling these exchanges. Surface albedo (α0), NDVI and surface temperature (T0) were the basic remote sensing retrieving parameters necessary to calculate the latent heat flux (λE) and the surface resistance to evapotranspiration (rs) on a large scale. The daily net radiation (Rn) was obtained from α0, air temperature (Ta) and short-wave transmissivity (τsw) throughout the slob equation, allowing the quantification of the daily sensible heat flux (H) by residual in the energy balance equation. With a threshold value for rs, it was possible to separate the energy fluxes from crops and natural vegetation. The averaged fractions of Rn partitioned as H and λE, were in average 39 and 67%, respectively. It was observed an increase of the energy used for the evapotranspiration process inside irrigated areas from 51% in 1992 to 80% in 2011, with the ratio λE/Rn presenting an increase of 3 % per year. The tools and models applied in the current research, can subsidize the monitoring of the coupled climate and land use changes effects in irrigation perimeters, being valuable when aiming the sustainability of the irrigated agriculture in the future, avoiding conflicts among different water users. © 2012 SPIE.

Energy balance for ethyl alcohol production from crops

Energy requirements to produce ethyl alcohol from three different crops in Brazil (sugarcane, cassava, and sweet sorghum) were calculated. Figures are presented for the agricultural and industrial phases. The industrial phase is always more energy-intensive, consuming from 60 to 75 percent of the total energy. Sugarcane is the more efficient crop for ethyl alcohol production, followed by sweet sorghum and cassava from a net energy viewpoint. The utilization of sweet sorghum stems might increase the total energy gain from this crop to almost the same level as sugarcane. Cassava has a lower energy gain at the present state of agriculture in Brazil. Copyright © 1978 AAAS.

Bioenergy from stillage anaerobic digestion to enhance the energy balance ratio of ethanol production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Multiobjective 0-1 integer programming for the use of sugarcane residual biomass in energy cogeneration

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Solar energy budgets in central Amazonian ecosystems: a comparison between natural forest and bare soil areas

In order to estimate the deforestation consequences on the actual solar energy budget of the Central Amazon Region, two ecosystems of different characteristics were compared. The present conditions of the region were represented by a typical 'terra firme' forest cover located at INPA's Ducke Forest Reserve, where the measurements necessary to evaluate its solar energy balance were carried out. The second ecosystem, simulating a deforested area, was represented by an area about 1.0 ha without natural vegetation and situated in the same Reserve. In this area lysimeters were placed, two of them filled with yellow latosol and two others with quartzose sand soil. Both soils are representative soils in the region. Their water balances were taken into account as well as the other parameters necessary to compute the solar energy balances. The results showed that water loss by evaporation was about 41.8% of the total precipitation in the yellow latosol lysimeters and about 26.4% for the quartzose sand ones. For the forest cover it was estimated an evapotranspiration of 67.9% of the rainfall amount. In relation to solar energy balance calculated for the forest cover, it was found that 83.1% of the total energy incoming to this ecosystem was used by the evapotranspiration process, while the remaining of 16.9% can be taken as sensible heat. For bare soils, 55.1% and 31.8% of the total energy were used as latent heat by yellow latosol and quartzose sand soils, respectively. So, the remaining amounts of 44.9% and 68.2% were related to sensible heat and available to atmospheric air heating of these ecosystems. Such results suggest that a large deforestation of the Amazon Region would have direct consequences on their water and solar radiation balances, with an expected change on the actual climatic conditions of the region. © 1993.

Optimal energy generation with biomass of sugarcane harvest

The aim of this work is the application of the Interior Point and Branch and Bound methods in multiobjective optimization models related to sugarcane harvest residual biomass. These methods showed their viability to help on choosing the sugarcane planting varieties, searching to optimize cost and energy balance of harvest residual biomass, which have conflitant objectives. These methods provide satisfactory results, with fair computing performance and reliable and consistent solutions to the analyzed models. © 2011 IEEE.

Organic coffee under perspective of energy efficiency

The energy analysis development in this study contributes to the understanding of the dynamics of the organic coffee productive system, in particular to assess the independence of this system with respect to the use of industrialized input products. Thus, it provides information about the sustainability of that production system. Technical itineraries used in this study consist of energy expenditure made with coffee cultivation, according to the type, source and form of energy inputs, agricultural machines, equipment and labor force used in that production system. The energy expenditure, converted into energy units, quantified the input energy. And the organic coffee production, measured in kilograms of processed coffee beans, was the output energy. Primary data used in this study were obtained from organic coffee producers in the Southern region of Minas Gerais State, Brazil, in 2011. Energy balance identified was positive, since the estimated output energy was 626.465 MJ/ha and the energy expenditure was 112.998 MJ/ha, during the useful life of the crop.

Analysis of the Priestley-Taylor alpha parameter for a bean crop

This work deals with the Priestley-Taylor model for evapotranspiration in different grown stages of a bean crop. Priestley and Taylor derived a practical Formulation for energy partitioning between the sensible and latent heat fluxes through the a parameter. Bowen ratio energy balance (BREB) was carried out for daily sensible and latent heat flux estimations in three different crop stages. Mean daily values of Priestley-Taylor a parameter were determined for eleven days during the crop cycle. Diurnal variation patterns of a are presented for the growing, flowering and graining periods. The mean values of 1.13 +/- 0.33, 1.26 +/- 0.74, 1.22 +/- 0.55 were obtained for a day in the growing, in the flowering and for graining periods, respectively. Eleven days values of a are shown and gave a mean value of 1.23 +/- 0.10 which agree on the reported literature.

Digestibilidade das dietas e metabolismo de suínos alimentados com dietas contendo bentonita sódica em diferentes programas alimentares

Foi realizado um experimento para avaliar a digestibilidade aparente de dietas e o metabolismo de suínos alimentados com dietas contendo bentonita sódica submetidos a diferentes programas alimentares. Foram utilizados 24 suínos machos castrados, meio irmãos paternos, com peso vivo médio inicial de 42,2kg, alojados em gaiolas metabólicas. O delineamento experimental foi o inteiramente casualizado com três níveis de bentonita sódica (0,0; 0,3 e 0,5%) e dois programas alimentares (restrito e à vontade), com oito repetições cada. A adição de bentonita sódica não alterou (P>0,05) o consumo de ração e os balanços da energia e do nitrogênio. O consumo de ração diferiu (P<0,01) entre a alimentação restrita e à vontade (1,17 vs. 2,19kg d-1). O programa alimentar alterou (P<0,05) o balanço do N, mas não afetou (P>0,05) a retenção de N pelos animais. A alimentação à vontade alterou (P<0,05) o balanço da energia, sobretudo a energia retida (3.825 vs. 3.013kcal d-1). A adição de 0,5% de bentonita sódica nas dietas reduziu em 9% (P<0,01) a excreção fecal de fósforo. A adição de bentonita sódica nas dietas de suínos não altera os balanços da energia e do N nem as digestibilidades aparentes do Ca, Mg, Zn, Cu e Mn. A adição de bentonita sódica reduz a excreção fecal de fósforo. Não há interação entre o programa alimentar e a adição de bentonita sódica nas dietas.

Análise energética em sistema de produção de suínos com aproveitamento dos desejos como biofertilizante em pastagem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Balanço de radiação e energia da cultura de alface em estufa de polietileno

Objetivou-se, neste trabalho, determinar os balanços de radiação e energia da cultura de alface (Lactuca sativa, L. cv. Verônica) em estufa de polietileno. O experimento foi realizado em uma estufa tipo túnel alto com cobertura de polietileno (100 mim de espessura) e em uma área externa, ambas com 35 m². Durante o ciclo da cultura, foram monitoradas as radiações global e refletida, saldo de radiação, fluxo de calor no solo e temperatura do ar (seca e úmida) nos dois meios. Utilizou-se um Datalogger que operou na freqüência de 1 Hz, armazenando médias de cinco minutos. A partir das integrações diárias das irradiâncias global (K¯) e refletida (K­), verificou-se que a transmissividade média da radiação global (K¯in / K¯ex) foi aproximadamente constante, em torno de 79,59%, enquanto a razão das radiações refletidas (K­in / K­ex) foi igual a 69,21% com coeficiente de variação de 8,47%. As curvas normalizadas do saldo de radiação de ondas curtas em relação à radiação global (K* / K¯), nos dois meios, mostraram ser aproximadamente constantes no início do ciclo e decrescentes no final. A relação (Rn/ K¯) foi maior no meio externo, em torno de 12%, a partir da fase em que a superfície verde da cultura cobriu o solo. O balanço médio (L*) de radiação de ondas longas foi maior no exterior, em torno de 50%. O balanço de energia, estimado em termos de fluxos verticais, mostrou, em média, que: no exterior, 83,07% do saldo de radiação foi convertido em calor latente (LE), 18,00% em fluxo de calor no solo (G) e 9,96% em calor sensível (H), enquanto que, no interior da estufa, 58,71% do saldo de radiação foi convertido em LE, 42,68% em H e 28,79% em G.