Investigation of sustainable energy alternatives for powering remote communities in northern Ontario

ABSTRACT

Remote communities in the North of Ontario survive in isolation as their proximity to the southern industrial sector of the province limits their accessibility to the major grid. The lack of grid connection has led to antiquated methods of power generation which pollute the environment and deplete the planet of its natural resources. Aside from the primary means of electricity generation being by diesel generators, generation infrastructure is deteriorating due to age and the stagnation of the power supply has led to communities facing load restrictions. These challenges may be resolved by introducing clean energy alternatives and providing a fuel blend option. The primary energy sources investigated in this research are solar, wind, and hydrogen. To assess the viability of these energy production methods in Northern communities, an exergy analysis is employed as it utilizes both the first and second law of thermodynamics to determine systems’ efficiency and performance in the surroundings. Local weather patterns were used to determine the viability of using wind turbines, solar panels and/or hydrogen fuel cells in a remote community. Through analysis of the resources available at the community, it was determined that the hydrogen fuel cell was best suited to provide clean energy to the community. Wind resulted in low efficiency in the range of 2–3% while solar efficiencies resulted in ranges of 18 – 19%, as the seasonal variations between the three years is not very great. Due to the higher operating efficiencies observed of the PV panels it would also be an attractive alternative to diesel generators however, the lack of consistent operation above 30% efficiency throughout the year, resulted in hydrogen fuel cells being a better alternative.     

Investigation of Environmental Effects Based on Exergetic Irreversibility for Display Cases’ Units in Commercial Cooling

This study examines energetic and exergetic performances of display cases’ units used in market applications depending on different refrigerants. Besides CO₂ emission potential of each refrigerant based on exergetic irreversibility obtained from analyses is calculated by the method of Total Equivalent Warming Impact (TEWI). In this study, 1 kW cooling capacity and vapor compression cooling cycle is taken as reference and refrigerants of R-22, R-134a, R-404A, and R-507 together with alternative refrigerant R-407C and R152a are examined separately. According to analyses, R-404A gas, used widely in market applications, has low performance with average COP 3.89 and average exergy efficiency 55.20%. R-152a gas has the best performance by the thermodynamics parameters including COP 4.49, exergy efficiency 63.79%, and 0.23 kW power consumption and emission parameter 14097.490 ton CO₂/year. Although COP is used as a criterion to evaluate the systems, this study finally emphasizes the importance of exergy analysis and TEWI method which are important methods to determine irreversibility and emission potential of the systems.     

Exergetic Sustainability Indicators as a Tool in Commercial Aircraft: A Case Study for a Turbofan Engine

This paper focuses on the exergetic sustainability indicators of a medium-range commercial aircraft engine for constant reference environment and ground running conditions. First, a detailed exergy analysis of turbofan engine have been performed based on engine test cell parameters. Starting from the sustainability considerations and the second law of the thermodynamics, the paper presents six exergy-based sustainability indicators. The indicators of the turbofan engine developed here in conjunction with exergetic analysis and sustainable development are exergy efficiency, waste exergy ratio, exergy destruction factor, recoverable exergy rate, environmental effect factor, and exergetic sustainability index. The investigated sustainable indicators have been calculated by using exergy analysis outputs for aircraft ground running condition. Results from this study show that values of exergy efficiency, waste exergy ratio, exergy destruction factor, recoverable exergy rate, environmental effect factor, and exergetic sustainability index of investigated turbofan engine are found to be 0.315, 0.685, 0.408, 0, 2.174, and 0.460, respectively. These parameters are expected to quantify how the turbofan engine and aircraft become more environmentally benign and sustainable.     

Effluent stream treatment in a nitrogenous fertilizer factory: An exergy analysis for process integration

The industrial processes used for the production of nitrogenous fertilizers are the main generators of reactive nitrogen compounds, chemicals and effluents that ultimately impact the biosphere. Exergy analysis has been performed to a nitrogen fertilizer factory in the State of Bahia, Brazil, where the Anaerobic Ammonium Oxidation (Anammox) and other physical–chemical processes are used to partially or totally handle the feed streams normally sent to a stripping tower.The results showed that the combined use of physical–chemical and biological process can improve the overall exergetic efficiency and avoid the emission of reactive compounds to the atmosphere allowing the recovery of the condensate lost as effluent, so that it can be reincorporated in the production of steam network, increasing energy efficiency and environmental performance of the process.     

Estimation of thermodynamic parameters of the biosphere, based on remote sensing

A method that allows the estimation of the thermodynamic parameters of the biosphere has been developed. It results in the subdivision of the following four phase states of the biosphere: three equilibrium states: “white planet” with high albedo and low entropy; temperate forest in winter with high entropy; and desert with high entropy; and one nonequilibrium state: the “active forests” with low entropy, high information gain and the highest exergy values. The phase shift to a nonequilibrium state happens when albedo is less than 0.2.     

Ecosystems emerging. 5: Constraints

Ecosystem constraints are both ontic and epistemic. They limit activity, and as problems to be solved they drive organization, which is our hypothesis:

The driver of organization is constraint.

Solutions proliferate further constraints in an unending spiral of problem (constraint) generation and solution. As constraints proliferate, behavior narrows, and species diversify to compensate (paradox of constraint). Resource enrichment reduces constraints, releases behavior, and reduction of challenges decreases diversity (paradox of enrichment)—high diversity is expressed in low-resource environments and low diversity in high-resource environments. A three-part model of constraints is formulated for non-living systems, and also for goal-directed, problem-solving biota. Mode 1: dynamical means behavior is co-determined by internal states and external inputs. Mode 2: cybernetic employs negative feedback to keep dynamics within goal-oriented operating limits. Mode 3: model-making entails ability to represent (model) physical reality and respond to both phenomenal (modeled) and physical inputs; this property distinguishes living from nonliving systems. Principal sections of the paper elaborate dynamical constraints (three classes), boundary constraints (expressed in edge effects and trophic dynamics), physical constraints (space, time, temperature), chemical constraints (environment fitness, ecological stoichiometry, chemical evolution, limiting factors), coding constraints (environmental vs. genetic coding), network and pathway constraints (connectivity), and natural selection constraints (fitting to the biosphere). Consideration of how the world would look without constraints suggests how fundamental these are in ecosystem emergence, and how the next property in this series, differentiation, would be unmotivated without them. We conclude that constraints as a category are under-studied in ecology, poorly understood in ecological phenomenology, and (our hypothesis) comprise a ubiquitous organizing force in nature.     

Forest growth in the light of the thermodynamic theory of ecological systems

The observed growth of a particular forest stand can be described by many models and explained by some of them. The forest growth models are also successfully applied for extrapolating the growth curve. However, the known models of forest growth are not “one-point” models. They are not designed to predict the future growth of a forest stand from its current state: the model parameters either are not directly measurable or cannot be measured with relevant accuracy. This article is an attempt to use Jørgensen–Svirezhev theory as a new clue to the choice of variables that determines forest growth. The postulates of this theory combined with the pipe theory of tree growth lead to conclusion that biomass of a stand should be proportional to the four-fifths power of its age. Empirical validation, however, disclosed that calendar age is rather approximate measure of ecosystem ontogeny. Delayed development or intensive thinning of a forest stand at the early stages leads to rejuvenation bias. Thus derived 4/5-law model approximates well-known Chapman–Richards model in the neighborhood of the inflection point, and is applicable to middle-aged forest stands.     

The free energy and information embodied in the amino acid chains of organisms

It is generally accepted as a useful and workable hypothesis that when an ecosystem receives an inflow of exergy (energy that can do work) it will utilize this flow of exergy to move as far away from thermodynamic equilibrium as possible after the exergy (energy) for maintenance has been covered. If more combinations of system components including organisms are offered, the combination of components and processes that will bring the system most away from thermodynamic equilibrium will win.The amino acid sequences of the proteins e.g. enzymes determine and control the life processes of the organisms and may be viewed as information sensu lato. The free energy of oxidation of the amino acids and the peptide bonds of the cell enzymes expresses therefore the exergy content, eco-exergy or work capacity that the information contributes to “moving further away from thermodynamic equilibrium”. In this paper eco-exergy is calculated and plotted versus the β-values (a measure of the information contained in the genome) for different organisms. The eco-exergy density was previously (see [J?rgensen et al., 1995] and [J?rgensen et al., 2005]) proposed to be calculated as the summation of the product of the β-values representing the information of the genome multiplied by the concentrations of the respective ecosystem components. This analysis shows a strong correlation between the β-values and free energy released when oxidizing the enzymes. The β-values can therefore be assumed to represent the free energy that the organisms have invested in genetic information.     

Exergoeconomic Environmental Optimization of Piston-Prop Aircraft Engines

In this study, exergy, exergoeconomic, exergoenvironmental analyses, and exergoeconomic environmental optimization are applied to a four-cylinder, spark ignition, naturally aspirated and air-cooled piston-prop aircraft engine in the cruise phase of flight for the first time to the best of the authors` knowledge. Here, three piston-prop aircraft engine parameters (altitude, air–fuel ratio (AF), and rated power setting (PS)) are selected for optimization purposes. All exergy, exergoeconomic, and exergoenvironmental values are calculated first. These values are then optimized to find the best results of all analyses. The best altitude, AF ratio, and PS values are finally found while the maximum exergy efficiency, the minimum product specific environmental impact, and the minimum average unit fuel exergy cost are obtained. The best results of optimization indicated that the maximum exergy efficiency varied between 19.54% and 19.80%, the minimum unit fuel exergy cost ranged from 126.30 $/GJ to 127.23 $/GJ, and the minimum specific environmental impact of production was in the range of 8.70–9.59 mPts/MJ. Based on the results obtained, for ensuring the optimum conditions, the low AF ratios and the low-altitude flight at high rated power settings have to be selected.