Emergy-based complexity measures in natural and social systems

Abstract

A complexity indicator based on the diversity of energy and resource uses by a system is proposed in this paper. The indicator is an emergy-based index of complexity derived from a modified Shannon information formula that provides a quantitative assessment of the diversity of sources. The emergy approach assigns to each driving input a weight that derives from the environmental work performed by nature in order to generate such resource. This quality assessment goes far beyond the simple accounting of mass and energy of input flows, but takes into proper account their interlinkage with the biosphere dynamics. The rationale of the proposed indicator is that complexity cannot be assessed by simply counting individuals, species and processes, but requires that focus is placed on several aspects of resource flows, namely their amount, frequency, and quality. Different mixes of emergy input flows originate different levels of growth and complexity. Systems that only rely on a small set of sources out of the large number potentially available possess a built-in fragility, that may determine their collapse in times of shrinking or changing resource basis. For validation purpose, the proposed indicator was applied to the performance of selected national economies (Nicaragua, Latvia, Denmark and Italy) in selected years and of the urban system of Roma (Italy) over a forty-year (1962-2002) historical series. Results point out an increasing complexity of the urban system of Rome over time, while a lower complexity was calculated for the investigated national systems as a whole (likely effect of nationwide averaging), with Italy ranking highest and Latvia lowest. The same assessment performed for the Italian agricultural system over a twenty-year time series (1985-2006) shows a decline of the emergy-adjusted Shannon indicator from about 75% down to 62%, while the decline was from 73% to 63% for the agriculture of Campania region (southern Italy).

Urban Studies Based on Emergy – A Review in Perspective of Causality

“…Some primary trials for urban system were illustrated in [9,10]. Hereafter, many emergy accounting studies emerged for Taipei, Rome, Beijing, Montreal, and urban subsystems [1,5,[11][12][13][14], which trace the components and scale of urban operations, which undoubtedly pertain to the material-cause-based methodology.…”

“…Emergy is defined as "all available energy that is used, directly and indirectly, in making a product, expressed in units of one type of energy" [3], which makes quality comparison among different types of energy possible. Therefore, emergy analysis is a supplier-side technique in revealing energy use of goods, fuel, labour, or service in the generalized form of solar energy [4,5]. As a systematic tool, emergy analysis has been widely applied to the global urban studies.…”

Renewability and sustainability of biogas system: Cosmic exergy based assessment for a case in China

“…The cosmic exergy indices are constructed with reference to those of solar emergy and exergy analysis [16,51,71,72]. Based on the cosmic exergy flows mentioned above (Ires-r, Ires-n, Ieco-r, Ieco-n and Y), five indices, NPEV, ERI, EYR, ELR and ESI are presented and explained below:…”

Multicriteria cost–benefit assessment of tannery production: The need for breakthrough process alternatives beyond conventional technology optimization

“…Emergy has been used in several different case studies, from the assessment of natural (Ulgiati et al, 2011a), agricultural (Agostinho et al, 2008;Bonilla et al, 2010;Giannetti et al, 2011), and industrial systems (Giannetti et al, 2008) to also assessing buildings and cities (Ascione et al, 2009;Conte and Monno, 2012;Mori and Christodoulou, 2012;Zucaro et al, 2014), and information (Abel, 2013). To perform an emergy evaluation, first the system under study must be represented by a detailed energy diagram using the energy system symbols proposed by Odum (1996).…”