Energy Flow Diagrams Research Articles

Modeling the Energetic and Exergetic Self-Sustainability of Societies With Different Structures

The paper examines global energy and exergy flows in various models of organized human societies: from primitive tribal organizations to teocratic/aristocratic societies, to the present industrial (and post-industrial) society, to possible future highly “robotized” or “central control” social organizations. The analysis focuses on the very general chain of technological processes connected to the extraction, conversion, distribution and final use of the real energetic content of natural resources (i.e., their exergy): the biological food chain is also considered, albeit in a very simplified and “humankind” sense. It is argued that, to sustain this chain of processes, it is necessary to use a substantial portion of the final-use energy flow, and to employ a large portion of the total work force sustained by this end-use energy. It is shown that if these quantities can be related to the total exergy flow rate (from the source) and to the total available work force, then this functional relationship takes different forms in different types of society. The procedure is very general: each type of societal organization is reduced to a simple model for which energy and exergy flow diagrams are calculated, under certain well-defined assumptions, which restrain both the exchanges among the functional “groups” which constitute the model, and the exchanges with the environment. It is argued that not all societies are unconditionally self-sustained, and that certain size and technology-related restrictions apply to virtually all types of societal organizations examined here. These restrictions limit in general the distribution of the active workforce among different productive sectors; this distribution cannot be arbitrarily assigned, but depends quantitatively on the technological level of the chain of processes connected with energy extraction, transformation, distribution, and use. The results can be quantified using some assumptions/projections about energy consumption levels for different stages of technological development which are available in the literature; the procedure is applied to some models of primitive and pre-industrial societies, to the present industrial/post-industrial society, and to a hypothetical model of a future, high-technology society. No attempt has been made to study transient behavior (“evolution” or “decay” of a certain type of society), nor to relate quantitatively the steady-state case to resource conservation and environmental protection. For most of the cases examined here, neither resource scarcity nor finite biosphere capacity were considered as constraints.

Field enhancement on metallic wire gratings

The electromagnetic near field of metallic wire gratings is numerically investigated for wavelengths for which strong resonances occur in the diffracted orders coincident with high radiation losses. Energy flow diagrams confirm that this phenomenon can be explained by excitation of surface polaritons. The distributions of the electromagnetic fields exhibit strong enhancements in the vicinity of the wire surface. The enhancement factor depends on the conductivity and the geometry of the wires.

「深江丸」推進プラントの熱力学的性能評価

Following the 1st. report of the main diesel engine system, the results of the performance evaluation of the emergency electric propulsion system on“Fukae-maru”are descibed in this paper. This system consists of the 200kW differential drive shaft generator-motor, the hydraulic system to drive the armature, and their attachments.Experiments have been made varing propeller pich angle and varing the direction of armature rotation on calm sea. In the analysis, the entire plant is assumed to be a steady-flow system, and both the first-and the second-law of thermodynamics are employed in order to clarify not only the quantity of energy but also the quality of energy.In consequence of these analyses, it becomes clear that the method of this analysis is effective to evaluate the performance of the plant which has the several forms of energy like in this plant. And, the Sankey diagrams (energy-flow diagrams) and the exergy efficiencies of this plant are also obtained.

「深江丸」推進プラントの熱力学的性能評価

It is important for the energy saving to evaluate the performance of the marine propulsion plant in operation. The object of this study is the diesel propulsion system rated at 1, 103kW, installed in a training ship “Fukae-maru” (449 Gross Tonnage) owned by Kobe University of Mercantile Marine.Experiments have been made under the various loads of this engine on calm sea. In the analysis, the entire plant is assumed to be a steady-flow system, and both the first-and the second-law of thermodynamics are employed in order to clarify not only the quantity of energy but also the quality of energy.In consequence of these analyses, the places where the energy losses are generated in this plant are made known, and the Sankey diagrams (energy-flow diagrams) and the exergy efficiencies of this plant are also obtained.

Bivalve suspension-feeding dynamics and benthic-pelagic coupling in an eutrophicated marine bay

The open exposed Laholm Bay in the Kattegat is eutrophicated through riverine input, mainly of N. The benthic macrofauna down to 10 m depth (60 km 2) is dominated by the suspension-feeding bivalves Cardium edule and Mya arenaria. To estimate the seasonal and annual consumption of seston by the suspension-feeders in Laholm Bay, we carried out three sets of observations. (1) The abundance and biomass of the macrofauna in this depth interval were assessed along eight transects. (2) The secondary production of the two bivalves was estimated over a 10-month period in two sampling squares. (3) The filtration rate of C. edule was determined in natural seawater in laboratory experiments during different seasons. The bivalves can in theory filter all of the water volume down to 10 m in 3 days and, thus, make a significant impact on the phytoplankton concentration. In our study, however, they filtered only approximately half of their potential feeding capacity, perhaps because food availability was low due to low turnover close to the bottom or due to physical disturbance. The majority of the phytoplankton is exported from the bay. Bivalve abundance, biomass, production and growth rate were moderate and generally lower than in adjacent areas to the north. In autumn, the bivalves consumed >90% of the seston in comparison with net-zooplankton consumption. An energy-flow diagram for the bivalves is presented including estimates of bivalve N excretion and biodeposition.

The role of nematodes in low rate percolating filter sewage treatment works

The contribution and role of bacterivore nematodes in energy flow in two low rate percolating filter works was calculated based on field sampling and laboratory studies of feeding rates and energy ingestion, growth, reproduction and respiration. At both sewage works energy flow values peaked in May and January corresponding to peaks in nematode density and biomass. Simplified energy flow diagrams related to time are presented expressed for a core extending from the bed surface to its bottom. Nematode ingestion in the filter-beds exercised a distinct effect on the bacterial community such that in order to maintain steady-state conditions a mean bacterial doubling time ranging from 31 to 291 h was necessary at Caton Effluent Treatment Works and 87–4460 h at Carnforth ETW. Localized grazing effects, especially in the upper filter regions, exercised even greater effects, where a doubling time of 4 h may have been required on occasions. Oxygen consumption attributable to nematodes ranged from 0.03 to 2.7% of total community respiration at the two treatment works, suggesting that in general the direct role of nematodes is relatively small and they exert their greatest effect by grazing on bacteria.

Energy-flow in a Mytilus edulis culture in western Sweden

Energy-flow is described for a blue mussel long-line culture of 4 500 m 2 which settled in June 1978 and was harvested in March 1980. Food quality varied with season. Phytoplankton blooms contained >95% of the seston protein and carbohydrate. However, in winter, >90% of these substances were bound in detritus. Consequently mussel energy content declined in both winters. Current speed had a theoretical linear relationship with long-line numbers during non-winter months. Particulate retention in the culture centre was 15–50%, suggesting culture numbers could be nearly doubled without significant growth depression. Estimates of biomass, production, respiration, assimilation, ingestion and faeces production were incorporated into an energy-flow diagram for the 571-day study. The highest assimilation, 751 kJ m −2 day −1, took place in the second autumn. Overall respiration was 58%, production was 42% of assimilation, and 64% production remained as the mussel terminal biomass. Epifauna biomass was about 1% of the mussel biomass after 15 months. Production/mean biomass for the complete study was 2.7 and the yield at the best time for harvest (November–December 1979) was close to 36 000 g wet weight per m 2. An 80% assimilation efficiency estimate gave a faeces production close to that measured as the sedimentation rate and was considered a better evaluation than a 60% assimilation efficiency.

High-energy dye laser pumped by wall-ablation lamps

A guideline for the optimum design of linear wall-ablation lamps is presented with a simple empirical formula which describes the luminescent characteristics of lamps. The absolute luminescent efficiency of the wall-ablation lamp was measured. A high-energy dye laser with a quadruple-elliptical cylindrical cavity was constructed using these lamps, and an output energy of 23.3 J (11.6 MW) was obtained with an overall efficiency of 0.31 %. The energy-flow diagram of this laser system was computed with a rate-equation analysis, and the conversion efficiency from electrical input to laser output was determined. One can expect an overall efficiency of about 2 %.

The ecology of kelp bed communities in the Benguela upwelling system

Cool nutrient rich waters combined with a rocky coastline extending infratidally make the west coast of South Africa well suited to growth of kelp species. The kelp bed community is compared with the main kelp beds studied elsewhere (Nova Scotia, W. Europe, California). All these areas have cool, nutrient-rich water but the Benguela region differs in that large swells prevail. This paper deals with the determination of faunal and algal boundaries in these kelp beds (composed mainly ofEcklonia maxima andLaminaria pallida), as well as their biomass, in order to build a descriptive model of the food web. The main components of a site representative of the variable kelp beds on the west coast of the Cape Peninsula (Oudekraal) have been identified and quantified in terms of ash-free dry weight and Joules. The study covered an area from the rocky intertidal zone to the rock/sand interface found at a depth of 20 m. The site was divided into different areas (offshore, intermediate, inshore), and these were subdivided into depth zones of 4 m to show up any differences with depth. Different sampling techniques using SCUBA were combined to cover a wide range of organisms in the survey. Horizontal and vertical surfaces were differentiated. Kelp holdfasts were removed as a sampling unit for the infauna study. The distribution data of the organisms, other than kelp, were studied by means of multivariate methods which confirmed the division into inshore, mediate and offshore associations. Differences in faunal and floral composition could be detected between horizontal and vertical surfaces. Kelp biomass data showed high average standing crop in the inshore and mediate locality compared to the low offshore values. Maximum standing crop values, however, were not reduced. Mechanisms regulating the kelp bed structure are discussed. In the inshore and intermediate areas, algal biomass is much higher than animal biomass. A fact emerging from the data is that there is relatively little biomass of grazers; the major primary consumers are filter feeders. Problems of turnover rates are mentioned and an energy flow diagram for the area is proposed and its validity discussed.

The meathop wood and the pasoh rainforest projects

The Meathop Wood Project involved the study of a deciduous broad-leafed forest in Lancashire and an attempt has been made to obtain an energy balance for the community and to elucidate carbon and mineral cycling. Measurements have been made of radiation, rate of photosynthesis by the major components of the forest and their productivity. The rate of litter fall, sub-divided into the various components such as eaves, bracts, branches, etc., root productivity and the death of the roots and the addition of organic matter to the soil from this source were measured. The decomposition of the soil litter was followed, and the soil populations of the animals, fungi and bacteria were examined. The mineral uptake by various plant species was followed by monitoring the incoming rain, the through-fall in its passage through the leaf canopy, the trunk-flow and run-off and the leaching of the litter and soil. The processes involved have been summarized in a general energy flow diagram for the forest. Because of the detailed work undertaken by members of the Nature Conservancy staff, much of which was begun before the I.B.P. started, it was possible with the aid of additional workers from universities and the Liverpool Technical College to fill many of the gaps in the original work. Similar but less complete studies were made jointly with the I.B.P. Committees of Japan and Malaysia on a virgin tropical lowland dipterocarp forest situated in Negri Sembilan in central Malaya.

Energy, Environment and Conservation

Materials in this article include fuels as well as structural materials. In the analysis of amounts of energy required to produce usable substances, energy, materials, and dollars are exchangeable. Society must know the energy requirements of all industrial materials for many purposes. The most important are for determining the energy intensiveness of specific materials, the national requirements for specific materials industries, and energy flow diagrams paralleling process flow diagrams. A knowledge of these factors aids in energy conservation practices in present systems and in minimizing energy requirements in developing new technologies. Energy requirements are discussed and presented in tabular form for: metallic materials, nonmetallic materials, fuels, electricity, plastics, and chemicals. Each has its own level of energy intensiveness, and there are many ways in which energy can be lost or saved in the total economic system. (MCW)

A Simple Model for Environmental Courses

Research Article| October 01 1975 A Simple Model for Environmental Courses Orin G. Gelderloos Orin G. Gelderloos Search for other works by this author on: This Site PubMed Google Scholar The American Biology Teacher (1975) 37 (7): 426–429. https://doi.org/10.2307/4445319 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Cite Icon Cite Search Site Citation Orin G. Gelderloos; A Simple Model for Environmental Courses. The American Biology Teacher 1 October 1975; 37 (7): 426–429. doi: https://doi.org/10.2307/4445319 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentThe American Biology Teacher Search This content is only available via PDF. Copyright 1975 National Association of Biology Teachers Article PDF first page preview Close Modal You do not currently have access to this content.

Available Energy Conversion and Utilization in the United States

The manner is which energy resources are consumed is examined, and attention is focused on those processes that consume a significant quantity of energy and do so least efficiently. The performance of a large number of energy conversion and utilization systems is investigated and the energy flows in the U.S. are illustrated from an available energy viewpoint. An available energy flow diagram showing the available energy supply by fuel type as well as the available energy requirements and losses in each of the four sectors (utility, residential and commercial, transportation, industrial) is presented. The available energy flow diagram shows a much bleaker picture of the U.S. energy utilization than do energy flow diagrams. The available energy flow diagram (which shows a thermodynamically truer performance picture than the energy flow diagram) points out the residential, commercial and transportation sectors as being substantially poorer in performance.

A Summary of the Loch Leven IBP Results in relation to Lake Management and Future Research

SynopsisThe International Biological Programme provided resources and enabled the work of a considerable number of researchers to be focused on physical, chemical and biological studies on Loch Leven, Kinross. In this paper the results are summarised with the help of an energy flow diagram and relationships between different trophic levels discussed. Major gaps in our knowledge, which have still to be worked on before all the relationships between different trophic levels can be well understood, have been highlighted. The causes of changes which have been recorded at Loch Leven and the unusual variability in the ecosystem are discussed and hypotheses presented. Profitable lines for future research are suggested, particularly in relation to the management of the loch as a National Nature Reserve and a brown trout fishery.

Ecology of a New England Salt Marsh

Measurements of the abundance of major populations, their metabolism, and the seasonal patterns of total system metabolism throughout a year were used to develop energy—flow diagrams for a New England salt—marsh embayment. The annual ecological energy budget for the embayment indicates that consumption exceeds production, so that the system must depend on inputs of organic detritus from marsh grasses. Gross production ranged from almost zero in winter to about 5 g O2 m—2 day—1 in summer. Respiration values were similar, but slightly higher, with the maximum difference observed in fall. Populations of shrimp and fish were largest in fall, with a much smaller peak in spring. Few animals were present in the embayment from May to July, but fall populations of shrimp ranged from 250 to 800 m—2 and fish averaged over 10 m—2. Birds were most abundant in winter and spring. In spite of high numbers, no evidence was found that the marsh embayment exported large amounts of shrimp or fish to the estuary. Production of aboveground emergent grasses on the marsh equaled 840 g m—2 for tall Spartina alterniflora, 432 g m—2 for short S. alterniflora, and 430 g m—2 for S. patens. These values are similar to those for New York marshes, but substantially lower than the southern marsh types. The efficiency of production of marsh grasses in the New England marsh was lower than reported for southern areas. A simulation model based on the laboratory and field metabolism and biomass measurements of parts of the embayment system was developed to predict diurnal patterns of dissolved oxygen in the marsh. The model was verified with field measurements of diurnal oxygen curves. The model indicated the importance of the timing of high tides in determining oxygen levels and was used to explore simulated additions of sewage BOD and increases in temperature.

Energy flow diagrams

Although the concepts of “efficiency” or “coefficient of performance” are useful in relating the output to input energies of a system, they do not give any indication of the manner in which this input energy varies within the system.This shortcoming may be overcome by using “energy flow diagrams” which have the great advantage of providing a pictorial, yet mathematically accurate, representation of the energy balance of the system, from which an overall appreciation of the energy variations can be obtained at a glance.

Production Potential of a Seaweed–Lobster Community in Eastern Canada

An energy-flow diagram for the bottom community in the seaweed zone of St. Margaret's Bay, Nova Scotia, has been constructed, using previous estimates of seaweed production and observations on animal biomass and respiration rates. Annual seaweed production exceeded the annual consumption by herbivores by a factor of more than 10 (7000 vs. 572 kcal/m2 per year). This fact, plus observations of physical processes in the seaweed zone, indicate that most of the seaweed production is exported as particulate matter in suspension. Production rates of the American lobster (Homarus americanus) prey species exceed lobster ingestion rates, also by a factor of more than 10 (84 vs. 6 kcal/m2 per year). The difference is presumably consumed by lobster competitors. The available information suggests lobster production in the seaweed zone could be increased by reducing predation and competition for food, together with an increase in suitable shelter.

Energetics of low-order spectral systems

The potential vorticity equation and the barotropic vorticity equation represented in spectral form in terms of solid spherical harmonics have been truncated to allow interaction between only one planetary wave and an arbitrary zonal flow. The analytic solutions in time which ensue from these truncated systems have been investigated in terms of the allowed nonlinear energy transfers. An energy flow diagram including potential and kinetic energy has been prepared and shows the direction and magnitude of exchange as it depends on the initial conditions. Maximum energy transfers and limitations of exchange amongst wave components are discussed. The linear solutions are considered and evaluated in terms of the exact solutions. Phase propagation and momentum transport in these systems are also investigated. DOI: 10.1111/j.2153-3490.1971.tb00565.x

Large‐scale atmospheric energetics in the wave‐number domain

Observational studies of the atmospheric energy cycle involving large‐scale components of the general circulation, as measured by wave number around latitude circles, are reviewed. The relevant equations are set down in full form for a closed global system. All pertinent observational studies of the terms arising in these equations are listed chronologically, and the results of the most comprehensive of these studies are displayed in energy flow diagrams for winter and summer average conditions. The need for further work is suggested by the imbalances and omissions and the inadequacies of data coverage.

Secondary Productivity in Terrestrial Communities

Synopsis. Secondary productivity is one portion of energy flow in a community, which includes the ingestion and assimilation of energy, and the expenditure of energy in metabolism by consumer organisms. The purpose of this paper is to describe the ecological significance of energy flow in consumers and to discuss methods of measuring its components. Data pertaining to 20 terrestrial animal populations are presented. About 20% of the energy assimilated by invertebrates is manifested as net production, while only about 2% of the assimilated energy is represented by net production in populations of birds and mammals. The relationship between pro? duction and metabolism appears to depend on the capacity for homeothermy. For a given amount of assimilated energy, homeotherms produce less than heterotherms. The ecologist defines secondary produc? tivity as the net quantity of food or energy ingested that is transferred to the tissue of heterotrophs over a period of time. It is one component of the energy flow process diagramed in Figure 1. Secondary produc? tivity is expressed as an increase in biomass, e.g., as growth, deposition of fat, or birth of young. The ecologist is interested in this parameter because it is an index to the significance of a population in terms of food resources made available to other predatory populations in the food-chain. Applied fields, such as animal husbandry and wildlife management, seek to increase the total output and the extent of utilization of secondary productivity by man. The concepts of food-chain and food-web are central to the study of secondary pro? duction. The energy flow diagram in Fig? ure 1 need only be expanded to illustrate