Sergio Ulgiati

Monitoring patterns of sustainability in natural and man-made ecosystems

By means of a systemic analysis of the relationships among components of a systems web, the flows of energy and other resources converging to produce the output (biomass, biodiversity, assets, industrial products) can be evaluated on a common basis, i.e. the content of solar equivalent energy (hereafter, emergy; Odum, H.T., 1996. Environmental Accounting. Emergy and Environmental Decision-Making. Wiley, New York). Indices and ratios based on emergy flows can be calculated and used to evaluate the behavior of the whole system. Their dependence upon the fraction of renewable and nonrenewable inputs as well as locally available versus purchased inputs from outside is stressed. A new index of sustainability is also defined and applied to case studies. The trends of these indices provide useful information about the dynamics of economic systems within the carrying capacity of the environment in which they develop. When a particular sector or production process is focused on, instead of a national economy, emergy based indices provide insights into the thermodynamic efficiency of the process, the quality of its output, and the interaction between the process and its surrounding environment.

Emergy use, environmental loading and sustainability. An emergy analysis of Italy

Abstract Maximizing emergy flow is the new statement (Odum, 1988a, 1991) of Lotkas maximum power principle (1992a, b): self-organizing systems which maximize emergy flow and reinforce production are sustainable, the others are displaced by those with better reinforcement of their productive basis. An emergy analysis of the Italian system of economy and nature was performed in order to study its sustainability and emergy use. Indices of thermodynamic and economic vitality of Italy were evaluated and a comparison with indices of other developed and developing countries was performed.

Emergy evaluations and environmental loading of electricity production systems

Abstract Six electricity production systems are evaluated using energy and emergy (Environmental Accounting. Emergy and Environmental Decision Making. New York:Wiley, 1996. 370pp.) accounting techniques, in order to rank their relative thermodynamic and environmental efficiencies. The output/input energy ratio as well as the emergy-based emergy yield ratio (EYR) and environmental loading ratio (ELR) have been jointly used to explore and compare system performances. Generation of CO2 has also been accounted for in order to compare renewable and nonrenewable energy sources. The production systems include both plants using nonrenewable energy sources (natural gas, oil, and coal thermal plants) and the so-called renewable energy sources (geothermal, hydroelectric, and wind plants). A method for evaluating the environmental contribution to electric production is shown to provide important information that can be used to support the environmentally sound public policy. Renewable power plants were characterized by high energy return on investment, while fossil fueled plants exhibited average energy efficiency in the 25–36% range. EYR varied from a high of 7.6/1 for hydroelectric generation to about 4.2/1 for the oil thermal plant. The renewable energy plants required the highest environmental inputs per unit of output while fossil fuel plants required relatively small environmental inputs for cooling and to support fuel combustion. Environmental loading was highest with thermal plants. Using an emergy index of sustainability, it is quantitatively shown how renewable energy source plants like wind, hydroelectric, and geothermal had higher sustainability compared to thermal plants.

Feasibility of Large-Scale Biofuel Production

iofuels are widely seen as a feasible alternative to oil. Indeed, in 1995 the Clinton Administration proposed amendments to the Clean Air Act that would require gasoline sold in the nine most polluted US cities to contain additives from renewable sources, such as grain alcohol. This move, even if blocked by a three-judge panel of the US Court of Appeals in Washington, DC (Southerland 1995), has helped to focus attention on the question of whether research and development in biofuel production from agricultural crops should be increased (e.g., Abelson 1995). In Europe, similar fiscal and regulatory provisions have already been introduced (Chartier and Savanne 1992, Sourie et al. 1992). These policies assume that biofuels have the potential to reduce current dependence of industrialized societies on rapidly disappearing fossil energy stocks and that biofuels are desirable from an ecological point of view. But are these assumptions correct?

Emergy-based indices and ratios to evaluate the sustainable use of resources

Abstract By means of a systemic analysis of the relationships among components of an ecosystems web, the flows of energy and other resources converging to produce the output (biomass, biodiversity, assets, etc.) can be evaluated on a common basis, i.e. the content of solar equivalent energy (emergy). Indices and ratios based on the emergy flows can be calculated and used to evaluate the behaviour of the whole system. In this paper, one of these indices, the emergy yield ratio η (total yield emergy per unit of emergy invested) is evaluated and suggestions made to modify it to account for present and future environmental damages due to the use of a given resource. The meaning of this index, with and without the proposed modification, is stressed illustrating the long-term effects of environmental pollution as well as some key uncertainty factors that are very often not taken into account. Odum, 1993

Quantifying the environmental support for dilution and abatement of process emissions The case of electricity production

Abstract Strategies to deal with thermal and chemical emissions from electricity production processes are compared. Accounting for the environmental services required to dilute emissions is suggested as an unavoidable step towards correct evaluation of sustainability of processes. Calculations are performed in several case studies by means of the emergy accounting methodology. An emergy-based yield indicator decreases by 40–70% coupled to a parallel increase of a loading indicator, when the environmental services required for the dilution of pollutants are correctly accounted for. As a consequence of including environmental services, a lower sustainability is calculated for each investigated process when compared to evaluations that do not include them. Accounting for environmental services also provides a way to evaluate the carrying capacity of the environment in relation to human dominated processes. The requirement for environmental services to effectively recycle by-products at different space–time scales translates into the need for a suitable support area for the process under study. Two support areas are suggested, one using local constraints, and a second using global constraints. The former is suggested as a near term, regional carrying capacity, while the latter is a long term, global carrying capacity.

A Comprehensive Energy and Economic Assessment of Biofuels: When “Green” Is Not Enough

Referee: Dr. Charles A. S. Hall, Department of Environmental Studies, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210 Biofuel production systems are sometimes claimed to be able to fill in for future fossil fuel shortages as well as to decrease carbon dioxide emissions and global warming. As such, they are often promoted as a “green” alternative to fossil fuels. I present a comprehensive, system-based case study of biofuel production from maize or corn (Zea mays L.) and evaluate it critically in this review. The case study is taken as an example of the comprehensive approach that I suggest for any energy crop. I conclude that the biofuel option on a large scale is not a viable alternative based on economic, energy and eMergy (amount of available energy [exergy] of one form [usually solar] that is directly or indirectly required to provide a given flow or storage of exergy or matter) analyses of the case study data and estimated possible improvement of yield and efficiency. This is true for developed countries due to their huge energy demand compared with what biofuel options are able to supply as well as for developing countries due to the low yield of their agriculture and competition for land and water for food production. However, biofuels may contribute to optimizing the energy and resource balance of agricultural, livestock, or industrial production systems at an appropriate scale. I present a proposal to integrate ethanol production with industrial activities within a “zero emission framework” as a suggestion for optimization strategies capable of making the biofuel option more sustainable and profitable in those cases where it is appropriate.

Emergy Measures of Carrying Capacity to Evaluate Economic Investments

This paper outlines a method for determining carrying capacity for economic investments based on an emergy evaluation of the environmental resources of a region. Using data from tourism development in Mexico and Papua New Guinea, the concept of carrying capacity is related to intensity of development, environmental support area, and the “fit” of economic development in local environments and economies.Emergy, a unit of resource use and work potential, is used to quantitatively evaluate intensity of development. Emergy evaluation is briefly described and the evaluations of tourism used to further explain the methodology. The total annual resource use for the tourist resorts and the economies in which they are embedded (including inputs of renewable and nonrenewable resources and purchased goods and services) was calculated and converted to emergy units. The renewable resource base and an Environmental Loading Ratio (ELR), are proposed as a means for determining both long term and short term carrying capacity respectively. The concept of sustainable development is related to the net emergy benefits that result from development. Expressed as a ratio of the amount of emergy received by the local economy to the amount that is exported (embodied in tourists), sustainability is suggested to result from a positive emergy trade balance.

Multi-method and Multi-scale Analysis of Energy and Resource Conversion and Use

Optimizing the performance of a given process requires that many different aspects are taken into account. Some of them, mostly of technical nature, relate to the local scale at which the process occurs. Other technological, economic and environmental aspects are likely to affect the dynamics of the larger space and time scales in which the process is embedded. These spatial and time scale effects require that a careful evaluation of the relation between the process and its ‘surroundings’ is performed, so that hidden consequences and possible sources of inefficiency and impact are clearly identified. In this work the authors summarise a number of studies in which they applied a multi-method and multi-scale approach in order to generate a comprehensive picture of the investigated systems/processes. The benefits of such an integrated investigation approach are discussed.

Modelling entropy and exergy changes during a fluid self-organization process

Abstract The possibility and the need to describe a complex system behaviour by means of functions of state variables is stressed here, yielding a detailed calculation of exergy and entropy changes within a fluid model, according to input flows of available resources. This ‘from within’ approach is presented as an applied example of our previous claims (Ulgiati, S., Bianciardi, C., 1997. Ecol. Model. 96, 75–89) about the relevance of measures of far-from-equilibrium states based on internal and physically measurable state variables. The system model evolution to a thermodynamic equilibrium state is described, through different conduction, convection and chaos phases. Transition from conduction to convection is carefully investigated. Results are compared with literature ‘from outside’ descriptions based on assumed links between internal organization and input flows from outside.