Energy embodiment in Brazilian agriculture: an overview of 23 crops

Abstract

The amount of energy required to produce a commodity or to supply a service varies from one production system to another and consequently giving rise to differing levels of environmental efficiency. Moreover, since energy prices have been continuously increasing over time, this energy amount may be a factor that has economic worth. Biomass production has a variety of end-products such as food, energy, and fiber; thus, taking into account the similarity in end-product of different crops (e.g.: sunflower, peanuts, or soybean for oil) it is possible to evaluate which crops require less energy per functional unit, such as starch, oil, and protein.This information can be used in decision-making about policies for food safety or bioenergy. In this study, 23 crops were evaluated allowing for a comparison in terms of energy embodied per functional unit. Crops were grouped as follows: starch, oil, horticultural, perennial and fiber, to provide for a deeper analysis of alternatives for the groups, and subsidize further studies comparing conventional and alternative production systems such as organic or genetically modified organisms, in terms of energy. The best energy balance observed was whole sugarcane (juice, bagasse and straw) with a surplus of 268 GJ ha −1 yr −1; palm shows the highest energy return on investment with a ratio of approximately 30:1. For carbohydrates and protein production, cassava and soybean, respectively, emerged as the crops offering the greatest energy savings in the production of these functional foods.Keywords: EROI, starch, oil, fertilizer, fiber, energy balance requirements by Brazilian agriculture is important to an evaluation of its sustainability. Based on this view, this study aimed to evaluate the energy embodied in 23 crops and assess how much energy is used in their production as well as the energy return, in order to direct subsidies in accordance with an environmental friendly and energy-saving policy that will secure the food supply in Brazil. Materials and MethodsEnergy flows of the following 23 crops were assessed: maize; wheat, cassava, potato, rice, bean, soybean (produced in two Brazilian regions: system 1 in the state of Paraná and system 2 in the state of Mato Grosso), peanut, sunflower, castor bean (comparing two systems, system 1 using low-level technology and system 2 a higher level of machinery and technology; and a third group comprising palm, lettuce, banana, onion, carrot, cucumber, bell pepper, tomato, cotton, eucalyptus, citrus, coffee and sugarcane. For this group, three scenarios of energy output flow (EOF) were developed: the first considering the production of juice only, the second juice plus bagasse, and third juice, bagasse and straw as output.From the utilisation point of view, there are basically two types of material flow: i) inputs applied directly, such as limestone, fertilizers, seeds and other chemicals used that carry with them amounts of energy for the production process and are currently in use in the fields; and ii) inputs applied indirec...

A Web-Based Tool for Energy Balance Estimation in Multiple-Crops Production Systems

“…EOUA: Energy output per unit area (MJ ha −1 ). EIUM: Energy input per unit mass (MJ t −1 ), which express the energy intensity as defined in Veiga et al [31]. EB: Energy balance (MJ), expresses the difference: EB = EO − EI.…”

“…Accordingly, for food and byproducts, the EI (or EIUA and EIUM) are more suitable and can serve as the functional unit of any given crop [31].…”

“…Once field capacity has been estimated, the machinery (tractor or equipment) energy depreciation ( Figure 3) is calculated by [31]:…”

“…where is the embodied energy per unit mass of the machinery (MJ kg −1 ), M is the mass of the machinery (kg), is the useful lifetime of the machinery (h), and is the field capacity of the Once field capacity has been estimated, the machinery (tractor or equipment) energy depreciation ( Figure 3) is calculated by [31]:…”

Viabilidade energética e econômica da aplicação de fertilizantes em taxa variável

“…As principais fontes de demanda de energia na produção foram o combustível (39 %), pesticidas (31 %) e fertilizantes (24 %), identificado assim, os insumos que merecem maior atenção na tomada de decisão. Veiga et al (2015) A maioria de investigações mostraram a importância da fertilização e o uso dos insumos (N-P-K) para os sistemas agrícolas, destacando a avaliação energética como uma ferramenta de tomada de decisão que permite conhecer o efeito da prática com o ambiente. No entanto, ainda se carecem de estudos energéticos sobre a técnica de fertilização, que demostrem os benefícios e desvantagens para o produtor agrícola.…”