As noted by Electrek, Straubel has been known to invest in companies without any connection with Tesla, like his backing of new energy storage startup Axiom Exergy.
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Similar to thermomechanical exergy, chemical exergy depends on the temperature and pressure of a system as well as on the composition. The key difference in evaluating chemical exergy versus thermomechanical exergy is that thermomechanical exergy does not take into account the difference in a system and environment's chemical composition. If the temperature, pressure or composition of a system differs from the environment's state, then the overall system will have exergy. The definition of chemical exergy resembles the standard definition of thermomechanical exergy, but with a few differences.
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After finding the chemical exergy in a given system, one can find the total exergy by adding it to the thermomechanical exergy. Depending on the situation, the amount of chemical exergy added can be very small. If the system being evaluated involves combustion, the amount of chemical exergy is very large and necessary to find the total exergy of the system.
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This has led to substitution of more valuable high-exergy energy carriers with low-exergy energy carriers, when possible. An example is heating systems, where higher investment to heating systems allows using low-exergy energy sources. Thus high-exergy content is being substituted with capital investments.
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Exergy is a combination property of a system and its environment because it depends on the state of both the system and environment. The exergy of a system in equilibrium with the environment is zero. Exergy is neither a thermodynamic property of matter nor a thermodynamic potential of a system. Exergy and energy both have units of joules.
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In thermodynamics, the exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir, reaching maximum entropy. When the surroundings are the reservoir, exergy is the potential of a system to cause a change as it achieves equilibrium with its environment. Exergy is the energy that is available to be used. After the system and surroundings reach equilibrium, the exergy is zero.
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A common hypothesis in systems ecology is that the design engineer's observation that a greater capital investment is needed to create a process with increased exergy efficiency is actually the economic result of a fundamental law of nature. By this view, exergy is the analogue of economic currency in the natural world. The analogy to capital investment is the accumulation of exergy into a system over long periods of time resulting in embodied energy. The analogy of capital investment resulting in a factory with high exergy efficiency is an increase in natural organizational structures with high exergy efficiency.
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Exergy in a sense can be understood as a measure of value of energy. Since high-exergy energy carriers can be used in for more versatile purposes, due to their ability to do more work, they can be postulated to hold more economic value. This can be seen in prices of energy carriers, i.e. high- exergy energy carriers such as electricity tend to be more valuable than low- exergy ones such as various fuels or heat.
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The exergy destruction of a cycle can also be determined without tracing the individual processes by considering the entire cycle as a single process and using one of the exergy destruction equations.
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The amount of usable energy is the exergy of a system.
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In systems ecology, researchers sometimes consider the exergy of the current formation of natural resources from a small number of exergy inputs (usually solar radiation, tidal forces, and geothermal heat). This application not only requires assumptions about reference states, but it also requires assumptions about the real environments of the past that might have been close to those reference states. Can we decide which is the most "realistic impossibility" over such a long period of time when we are only speculating about the reality? For instance, comparing oil exergy to coal exergy using a common reference state would require geothermal exergy inputs to describe the transition from biological material to fossil fuels during millions of years in the Earth's crust, and solar radiation exergy inputs to describe the material's history before then when it was part of the biosphere.
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If the intensive properties of different finitely extended elements of a system differ, there is always the possibility to extract mechanical work from the system. The term exergy is also used, by analogy with its physical definition, in information theory related to reversible computing. Exergy is also synonymous with: available energy, exergic energy, essergy (considered archaic), utilizable energy, available useful work, maximum (or minimum) work, maximum (or minimum) work content, reversible work, and ideal work. The exergy destruction of a cycle is the sum of the exergy destruction of the processes that compose that cycle.
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In contrast, exergy is always destroyed when a process is irreversible, for example loss of heat to the environment (see Second Law of Thermodynamics). This destruction is proportional to the entropy increase of the system together with its surroundings (see Entropy production). The destroyed exergy has been called anergy. For an isothermal process, exergy and energy are interchangeable terms, and there is no anergy.
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Exergy is useful when measuring the efficiency of an energy conversion process. The exergetic, or 2nd Law, efficiency is a ratio of the exergy output divided by the exergy input. This formulation takes into account the quality of the energy, often offering a more accurate and useful analysis than efficiency estimates only using the First Law of Thermodynamics. Work can be extracted also from bodies colder than the surroundings.
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The ratio of exergy to energy in a substance can be considered a measure of energy quality. Forms of energy such as macroscopic kinetic energy, electrical energy, and chemical Gibbs free energy are 100% recoverable as work, and therefore have an exergy equal to their energy. However, forms of energy such as radiation and thermal energy can not be converted completely to work, and have exergy content less than their energy content. The exact proportion of exergy in a substance depends on the amount of entropy relative to the surrounding environment as determined by the Second Law of Thermodynamics.
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Exergy output will not balance the exergy input for real processes since a part of the exergy input is always destroyed according to the Second Law of Thermodynamics for real processes. After the input and output are completed, the engineer will often want to select the most efficient process. An energy efficiency or first law efficiency will determine the most efficient process based on wasting as little energy as possible relative to energy inputs. An exergy efficiency or second-law efficiency will determine the most efficient process based on wasting and destroying as little available work as possible from a given input of available work.
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The internal energy of a system is always measured from a fixed reference state and is therefore always a state function. Some authors define the exergy of the system to be changed when the environment changes, in which case it is not a state function. Other writers prefer a slightly alternate definition of the available energy or exergy of a system where the environment is firmly defined, as an unchangeable absolute reference state, and in this alternate definition exergy becomes a property of the state of the system alone. However, from a theoretical point of view, exergy may be defined without reference to any environment.
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Radiant systems are associated with low-exergy systems. Low-exergy refers to the possibility to utilize ‘low quality energy’ (i.e. dispersed energy that has little ability to do useful work). Both heating and cooling can in principle be obtained at temperature levels that are close to the ambient environment.
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Chemical exergy is defined as the maximum work that can be obtained when the considered system is brought into reaction with reference substances present in the environment. Defining the exergy reference environment is one of the most vital parts of analyzing chemical exergy. In general, the environment is defined as the composition of air at 25 °C and 1 atm of pressure. At these properties air consists of N2=75.67%, O2=20.35%, H2O(g)=3.12%, CO2=0.03% and other gases=0.83%.
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Application of exergy to unit operations in chemical plants was partially responsible for the huge growth of the chemical industry during the 20th century. During this time it was usually called availability or available work. As a simple example of exergy, air at atmospheric conditions of temperature, pressure, and composition contains energy but no exergy when it is chosen as the thermodynamic reference state known as ambient. Individual processes on Earth such as combustion in a power plant often eventually result in products that are incorporated into the atmosphere, so defining this reference state for exergy is useful even though the atmosphere itself is not at equilibrium and is full of long and short term variations.
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Besides the amount of radiation reaching a plant in the PAR region of the spectrum, it is also important to consider the quality of such radiation. Radiation reaching a plant contains entropy as well as energy, and combining those two concepts the exergy can be determined. This sort of analysis is known as exergy analysis or second law analysis, and the exergy represents a measure of the useful work, i.e., the useful part of radiation which can be transformed into other forms of energy. The spectral distribution of the exergy of radiation is defined as: : Ex_\lambda = L_\lambda(T) - L_\lambda(T_0) - T_0 [S_\lambda(T) - S_\lambda(T_0)] One of the advantages of working with the exergy is that it depends on the temperature of the emitter (the Sun), T, but also on the temperature of the receiving body (the plant), T_0, i.e.
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Exergy analysis now forms a common part of many industrial and ecological energy analyses. For example, I.Dincer and Y.A. Cengel (2001, p. 132) state that energy forms of different qualities are now commonly dealt with in steam power engineering industry. Here the "quality index" is the relation of exergy to the energy content (Ibid.).
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The software is designed for life insurance companies to assist them in the administration of their policies. In 2012, SilverBridge entered into a partnership with Net2Africa. Exergy celebrated its 10th anniversary in 2014. In the same year, the software saw the introduction of Exergy KnowledgeBase, designed to provide a way of reducing risk in IT projects.
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This maximizes the efficiency of exergy use. This strategy aims for a more efficient economy with fewer pollutants and other unwanted by-products.
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Exergy of a system is the maximum useful work possible during a process that brings the system into equilibrium with a heat reservoir. Wall clearly states the relation between exergy analysis and resource accounting. This intuition confirmed by DeWulf and Sciubba lead to Exergo-economic accounting and to methods specifically dedicated to LCA such as Exergetic material input per unit of service (EMIPS). The concept of material input per unit of service (MIPS) is quantified in terms of the second law of thermodynamics, allowing the calculation of both resource input and service output in exergy terms.
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In recent decades, utilization of exergy has spread outside of physics and engineering to the fields of industrial ecology, ecological economics, systems ecology, and energetics. Defining where one field ends and the next begins is a matter of semantics, but applications of exergy can be placed into rigid categories. Researchers in ecological economics and environmental accounting perform exergy-cost analyses in order to evaluate the impact of human activity on the current natural environment. As with ambient air, this often requires the unrealistic substitution of properties from a natural environment in place of the reference state environment of Carnot.
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Some proponents of utilizing exergy concepts describe them as a biocentric or ecocentric alternative for terms like quality and value. The "deep ecology" movement views economic usage of these terms as an anthropocentric philosophy which should be discarded. A possible universal thermodynamic concept of value or utility appeals to those with an interest in monism. For some, the end result of this line of thinking about tracking exergy into the deep past is a restatement of the cosmological argument that the universe was once at equilibrium and an input of exergy from some First Cause created a universe full of available work.
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Determining exergy was also the first goal of thermodynamics. The term "exergy" was coined in 1956 by Zoran Rant (1904–1972) by using the Greek ex and ergon meaning "from work", but the concept was developed by J. Willard Gibbs in 1873. Energy is neither created nor destroyed during a process. Energy changes from one form to another (see First Law of Thermodynamics).
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At the company's 2016 results, it was reported that Exergy is being used by businesses across Africa including in Angola, Botswana, Kenya, Malawi, Mauritius, and Ghana. In November 2016, it was reported that SilverBridge has done an implementation at GetSure Zimbabwe to help the company migrate its business to a cloud computing system. The solution was based on the Exergy system.
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These molar fractions will become of use when applying Equation 8 below. CaHbOc is the substance that is entering a system that one wants to find the maximum theoretical work of. By using the following equations, one can calculate the chemical exergy of the substance in a given system. Below, Equation 8 uses the Gibbs function of the applicable element or compound to calculate the chemical exergy.
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The company was established in 1994 as Pinnacle Mining NL. On 5 June 1998 it changed its name to Pinnacle VRB Limited. In 2006, the company acquired Cougar Energy Pty Ltd. After merger, the company changed name to Cougar Energy Limited on 16 February 2007. Cougar Energy had a licence agreement with Ergo Exergy Technologies for utilization of the underground coal gasification technology developed by Ergo Exergy.
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Apparently, total exergy cost of wind and natural-gas fired technologies are almost the same, but contrarily to the wind power plants, the non-renewable unit exergy costs of NG-fired power plants is practically equal to the total cost. This result is a consequence of the efficiency assumed for wind power plants. If energy storage is to be taken into account for intermittent technologies such as wind farms, the total exergy cost could be slightly increased. The upstream and downstream CO2 emissions in the coal route represent a very small part of the total CO2 emissions, if compared with the direct emissions of coal burning in the power plant.
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Again, the exergy of a system is determined by the potential of that system to do work, so it is necessary to determine the baseline qualities of a system before it is possible to understand the potential of that system. The thermodynamic value of a resource can be found by multiplying the exergy of the resource by the cost of obtaining the resource and processing it. Today, it is becoming increasingly popular to analyze the environmental impacts of natural resource utilization, especially for energy usage. To understand the ramifications of these practices, exergy is utilized as a tool for determining the impact potential of emissions, fuels, and other sources of energy.
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The destruction of exergy is closely related to the creation of entropy and as such any system containing highly irreversible processes will have a low energy efficiency. As an example the combustion process inside a power stations gas turbine is highly irreversible and approximately 25% of the exergy input will be destroyed here. For fossil fuels the free enthalpy of reaction is usually only slightly less than the enthalpy of reaction so from equations (3) and (4) we can see that the energy efficiency will be correspondingly larger than the energy law efficiency. For example, a typical combined cycle power plant burning methane may have an energy efficiency of 55%, while its exergy efficiency will be 57%.
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Although re- released in 2003 on the Exergy label, it was unavailable for a long time until it was re-released by the band in 2010 as a double CD.
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Zoran Rant (ca. 1964) Zoran Rant (14 September 1904 - 12 February 1972) was a Yugoslavian chemical engineer, scientist and professor, associate member of SAZU. Rant invented the terms exergy and anergy.
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This shows that, although almost renewable, the typical configurations of sugar cane bagasse-fired power plants are far from being efficient technologies. Hydro and wind farms present the lowest specific CO2 emissions as well as the lowest unit exergy cost. Due to the high participation of renewable sources in the production of electricity (near to 89% of the total), Brazilian electricity mix emissions are found to be 7.5 and 11.8 times lower than Europe and World electricity mixes. Also, owed to the higher efficiency of hydroelectric power plants, which contribute to the major part of the electricity generation in Brazil, the total unit exergy cost is lower, and thus, exergy efficiency of electricity generation is higher if compared with countries based on fossil fuels for electricity generation.
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Cougar Energy and Linc Energy conducted pilot projects in Queensland, Australia based on UCG technology provided by Ergo Exergy until their activities were banned in 2016. Yerostigaz, a subsidiary of Linc Energy, produces about of syngas per day in Angren, Uzbekistan. The produced syngas is used as fuel in the Angren Power Station. In South Africa, Eskom (with Ergo Exergy as technology provider) is operating a demonstration plant in preparation for supplying commercial quantities of syngas for commercial production of electricity.
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Team Exergy was a professional cycling team, classified as a Continental pro team as of 2009. They participated in the 2011 and 2012 USA Pro Cycling Challenge. Former Tour de France rider Fred Rodriguez was a member of the 2012 team. On 29 November 2012, it was announced that Exergy Development Group would drop its sponsorship of cycling for 2013, citing the doping scandals that had occurred recently, namely the USADA doping investigation of Lance Armstrong and the cycling team.
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Exergy is software developed by SilverBridge Holdings, a South African developer of business software for the financial services market in Africa. SilverBridge Holdings was listed on the AltX Stock Index on November 27th, 2006.
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In addition, the thermodynamic quantity exergy, i.e. measure of the useful work energy of a system, is one measure of value. Thermoeconomists argue that economic systems always involve matter, energy, entropy, and information.Baumgarter, Stefan. (2004).
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Of course, an excessively large number of intermediate compartments comes at a capital cost that may be too high. Testing this idea in living organisms or ecosystems is impossible for all practical purposes because of the large time scales and small exergy inputs involved for changes to take place. However, if this idea is correct, it would not be a new fundamental law of nature. It would simply be living systems and ecosystems maximizing their exergy efficiency by utilizing laws of thermodynamics developed in the 19th century.
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For a heat engine, the exergy can be simply defined as the energy input times the Carnot efficiency. Since many systems can be modeled as a heat engine, this definition can be useful for many applications.
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Some of those > wastes are merely inconvenient but others are harmful or toxic. The second > law says that energy becomes less useful (exergy is destroyed) by every > action. There is much more to be said along these lines.
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As the metal oxide also serves as the heat transfer medium in the chemical looping process, the exergy efficiency of the reforming and gasification processes like that for the combustion process is also higher as compared to the conventional processes.
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Kay, J. (2002). Kay, J.J. "On Complexity Theory, Exergy and Industrial Ecology: Some Implications for Construction Ecology." In: Kibert C., Sendzimir J., Guy, B. (eds.) Construction Ecology: Nature as the Basis for Green Buildings, pp. 72–107. London: Spon Press.
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Many industrial processes, like plastic and electronic fabrication, rely on the consumption of finite resources.Martin, M. and Parsapour, A. 2012. "Upcycling wastes with biogas production: An exergy and economic analysis". Venice 2012: International Symposium on Energy from Biomass and Waste (2012).
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In this way, a better comparison between the utilization of different fuels in the electricity generation can be achieved. An iterative calculation procedure is used to determine the unit exergy costs of electricity and processed fuels, since both electricity and processed fuel are used in their own production routes. As it was expected, fossil-fired power plants presents the highest specific CO2 emissions, with the coal-fired power plants leading the group. However, even though fossil- fired power plants presents the most marked environmental impacts, their total unit exergy costs are much lower than that presented by sugar cane bagasse- fired power plants.
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This would need to be carried out mathematically backwards through time, to a presumed era when the oil and coal could be assumed to be receiving the same exergy inputs from these sources. A speculation about a past environment is different from assigning a reference state with respect to known environments today. Reasonable guesses about real ancient environments may be made, but they are untestable guesses, and so some regard this application as pseudoscience or pseudo-engineering. The field describes this accumulated exergy in a natural resource over time as embodied energy with units of the "embodied joule" or "emjoule".
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Kay, J.J. "On Complexity Theory, Exergy and Industrial Ecology: Some Implications for Construction Ecology." In: Kibert C., Sendzimir J., Guy, B. (eds.) Construction Ecology: Nature as the Basis for Green Buildings, pp. 72–107. London: Spon Press. Retrieved on: 2009-04-01.
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These basic categories are utilized as the main components of a reference environment when examining how exergy can be defined through natural resources. Other qualities within a reference state environment include temperature, pressure, and any number of combinations of substances within a defined area.
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The team was founded in 2005 as ProMan Hit Squad, but in 2009 the team was renamed Twenty12 to reflect the team's focus on developing riders for the 2012 Olympic Games. This subsequently brought Exergy on board as a sponsor of the team as well as receiving UCI status. For the 2013 season (and after the 2012 Olympics) the team was renamed Exergy Twenty16 to reflect the new focus on the 2016 Olympic Games, however in late 2013 Exergy's sponsorship of the team ended. For the 2014 season the team dropped back down to a Nationally ranked elite women's team and primarily raced the US domestic circuit.
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However, it was realised that the term "energy output" refers to both the useful energy output and the non-useful energy output. (Note: that as given by P.K.Nag, an alternative name for 'useful energy' is 'availability' or exergy, and an alternative name for 'non-useful energy' is 'unavailability', or anergy (Nag 1984, p. 156)). But as E.Sciubba and S.Ulgiati observed, the notion of transformity meant to capture the emergy invested per unit product, or useful output. The concept of Transformity was therefore further specified as the ratio of "input emergy dissipated (availability used up)" to the "unit output exergy" (Sciubba and Ulgiati 2005, p. 1957).
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By definition, the exergy obtained by the receiving body is always lower than the energy radiated by the emitting blackbody, as a consequence of the entropy content in radiation. Thus, as a consequence of the entropy content, not all the radiation reaching the Earth's surface is "useful" to produce work.
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Equation 9 is similar but uses standard molar chemical exergy, which scientists have determined based on several criteria, including the ambient temperature and pressure that a system is being analyzed and the concentration of the most common components. These values can be found in thermodynamic books or in online tables.
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A 100% exergy efficient methane fired power station would correspond to an energy efficiency of 98%. This means that for many of the fuels we use, the maximum efficiency that can be achieved is >90%, however we are restricted to the Carnot efficiency in many situations as a heat engine is being used.
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If standard ambient conditions are used for calculations during chemical plant operation when the actual weather is very cold or hot, then certain parts of a chemical plant might seem to have an exergy efficiency of greater than 100% and without taking into account the non-standard atmospheric temperature variation can give an impression of being a perpetual motion machine. Using actual conditions will give actual values, but standard ambient conditions are useful for initial design calculations. One goal of energy and exergy methods in engineering is to compute what comes into and out of several possible designs before a factory is built. Energy input and output will always balance according to the First Law of Thermodynamics or the energy conservation principle.
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A common misconception is that the exergy efficiency compares a given cycle to a Carnot heat engine. This is incorrect because a Carnot engine is the most efficient heat engine possible, but not the most efficient device for creating work. Fuel cells, for instance, can theoretically reach much higher efficiencies than a Carnot engine.
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According to Ohta (1994, pp. 90–91) the ranking and scientific analysis of energy quality was first proposed in 1851 by William Thomson under the concept of "availability". This concept was continued in Germany by Z. Rant, who developed it under the title, "die Exergie" (the exergy). It was later continued and standardised in Japan.
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Teutenberg later on won the road race in Gatineau. The fifth World Cup Race, the Tour of Chongming Island, ended like the other years in a bunch sprint where Hosking finished fourth. The team performed really well in The Exergy Tour. Amber Neben won the second stage, an individual time trial and Teutenberg the queen stage.
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The Carnot method is an allocation procedure for dividing up fuel input (primary energy, end energy) in joint production processes that generate two or more energy products in one process (e.g. cogeneration or trigeneration). It is also suited to allocate other streams such as CO2-emissions or variable costs. The potential to provide physical work (exergy) is used as the distribution key.
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After decades in which all the analysis has been focused on emending the Von Karman model, Dewulf and Van Langenhove have introduced a model based on the second law of thermodynamics and exergy analysis.Dewulf J, and Van Langenhove H., “Exergetic material input per unit of service (EMIPS) for the assessment of resource productivity of transport commodities”. Resources Conservation and Recycling. 38(2), Pages: 161–174 (2003).
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Hubbert Peak vs Oil Production There is an active debate about most suitable sustainability indicator's use and by adopting a thermodynamic approach through the concept of "exergy" and Hubbert peaks, it is possible to incorporate all into a single measure of resource depletion.The exergy analysis of minerals could constitute a universal and transparent tool for the management of the earth's physical stock. Hubbert peak can be used as a metric for sustainability and depletion of non-renewable resources. It can be used as reference for many metrics for non-renewable resources such as: # Stagnating supplies # Rising prices # Individual country peaks # Decreasing discoveries # Finding and development costs # Spare capacity # Export capabilities of producing countries # System inertia and timing # Reserves-to-production ratio # Past history of depletion and optimism Although Hubbert peak theory receives most attention in relation to peak oil production, it has also been applied to other natural resources.
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More explicitly, an energy is not available to do useful work, where TR is the temperature of the coldest accessible reservoir or heat sink external to the system. For further discussion, see Exergy. Statistical mechanics demonstrates that entropy is governed by probability, thus allowing for a decrease in disorder even in an isolated system. Although this is possible, such an event has a small probability of occurring, making it unlikely.
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If the peak oil theory proves true, more explorations of viable alternative energy sources, could be more friendly to the environment. Rapidly advancing technologies can achieve a transition of energy generation, water and waste management, and food production towards better environmental and energy usage practices using methods of systems ecology and industrial ecology.Kay, J. (2002). "On Complexity Theory, Exergy and Industrial Ecology: Some Implications for Construction Ecology", pp.
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However, to fully realize the potential of a system to do work, it is becoming increasingly imperative to understand exergetic potential of natural resources, and how human interference alters this potential. Referencing the inherent qualities of a system in place of a reference state environment is the most direct way that ecologists determine the exergy of a natural resource. Specifically, it is easiest to examine the thermodynamic properties of a system, and the reference substances that are acceptable within the reference environment. This determination allows for the assumption of qualities in a natural state: deviation from these levels may indicate a change in the environment caused by outside sources. There are three kinds of reference substances that are acceptable, due to their proliferation on the planet: gases within the atmosphere, solids within the Earth’s crust, and molecules or ions in seawater. By understanding these basic models, it’s possible to determine the exergy of multiple earth systems interacting, like the effects of solar radiation on plant life.
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"Comparative LCAs for curbside recycling versus either landfilling or incineration with energy recovery" (12 pp). The International Journal of Life Cycle Assessment, 10(4), 273–284. Some scholars use emergy (spelled with an m) analysis, for example, budgets for the amount of energy of one kind (exergy) that is required to make or transform things into another kind of product or service. Emergy calculations take into account economics which can alter pure physics-based results.
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Sportsaga is the annual sports festival of the Institute of Chemical Technology, Mumbai organized by the Technological Association. It was established in 2005. A game in progress at Pidilite Pavilion In 2013, the Technological Association (Student Council) of ICT decided that Exergy would be merged with the other technical festivals of the Institute, YICC (Young Innovators Choice Competition) and YRC (Young Researchers Competition). This led to the creation of Vortex – The Chemfest.
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No additional thermodynamic laws are required for this idea, and the principles of energetics may confuse many issues for those outside the field. The combination of untestable hypotheses, unfamiliar jargon that contradicts accepted jargon, intense advocacy among its supporters, and some degree of isolation from other disciplines have contributed to this protoscience being regarded by many as a pseudoscience. However, its basic tenets are only a further utilization of the exergy concept.
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Also, the new participants in the process are not treated as passive learners at the feet of the experts, being coercively convinced through scientific demonstration. Rather, they will form an ‘extended peer community’, sharing the work of quality assurance of the scientific inputs to the process, and arriving at a resolution of issues through debate and dialogue.Funtowicz, S., and Ravetz, J.R., THE POETRY OF THERMODYNAMICS, Energy, entropy/exergy and quality, Futures, Vol. 29, No. 9. pp.
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The low temperature difference requires that the heat transmission takes place over relative big surfaces as for example applied in ceilings or underfloor heating systems. Radiant systems using low temperature heating and high temperature cooling are typical example of low-exergy systems. Energy sources such as geothermal (direct cooling / geothermal heat pump heating) and solar hot water are compatible with radiant systems. These sources can lead to important savings in terms of primary energy use for buildings.
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Thermal oxidizers can use a regenerative process for waste heat from industrial systems. Air conditioning units use electricity which ends up as heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility (or in thermodynamics lexicon a lower exergy or higher entropy) than the original energy source.
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Low temperature heat contains very little capacity to do work (Exergy), so the heat is qualified as waste heat and rejected to the environment. Economically most convenient is the rejection of such heat to water from a sea, lake or river. If sufficient cooling water is not available, the plant has to be equipped with a cooling tower to reject the waste heat into the atmosphere. In some cases it is possible to use waste heat, for instance in heating homes by cogeneration.
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Combustion of fossil fuels, for example, is examined with respect to assessing the environmental impacts of burning coal, oil, and natural gas. The current methods for analyzing the emissions from these three products can be compared to the process of determining the exergy of the systems affected; specifically, it is useful to examine these with regard to the reference state environment of gases within the atmosphere. In this way, it is easier to determine how human action is affecting the natural environment.
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The cleanup of the dioxin contamination on the bottom of the river is the subject of a major environmental lawsuit regarding the responsibility for the cleanup. In 2008 EPA reached a settlement with Occidental Chemical Corporation and Tierra Solutions Inc. to clean a portion of the polluted river. A New Jersey Superior Court judge, ruling in July and September 2011, stated that Occidental and Maxus Exergy Corporation (a subsidiary of YPF) are liable for remediation in other portions of the river.
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Environmental systems analytical tools: Differences and similarities including a brief case study on heat production using ecological footprint, MIPS, LCA and exergy analysis. MSc thesis, Systems Ecology, Stockholm University, StockholmWrisberg, N.; Udo de Haes, H. A.; Triebswetter, U.; Eder, P.; Clift, R. (2002). Analytical tools for environmental design and management in a systems perspective. Dordrecht: Kluwer Academic Publishers An expansion of the field has occurred and a number of scientific journals publish extensively on the application of ESA methods e.g.
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From 1976 to 1978 Bejan was a Miller research fellow in at the University of California Berkeley working with Chang-Lin Tien. In 1978 he moved to Colorado and joined the faculty of the Department of Mechanical Engineering at the University of Colorado in Boulder. In 1982 Bejan published his first book, Entropy Generation Through Heat and Fluid Flow. The book is aimed at practical applications of the second law of thermodynamics, and presented his ideas on irreversibility, availability and exergy analysis in a form for engineers.
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However energy engineers were aware that the notion of heat quality involved the notion of value – for example A. Thumann wrote, "The essential quality of heat is not the amount but rather its 'value'" (1984, p. 113) – which brings into play the question of teleology and wider, or ecological-scale goal functions. In an ecological context S.E. Jorgensen and G.Bendoricchio say that exergy is used as a goal function in ecological models, and expresses energy "with a built-in measure of quality like energy" (2001, p. 392).
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Bales of crushed steel ready for transport to the smelter The amount of energy saved through recycling depends upon the material being recycled and the type of energy accounting that is used. Correct accounting for this saved energy can be accomplished with life- cycle analysis using real energy values, and in addition, exergy, which is a measure of how much useful energy can be used. In general, it takes far less energy to produce a unit mass of recycled materials than it does to make the same mass of virgin materials.Morris, J. (2005).
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Exergy efficiency (also known as the second-law efficiency or rational efficiency) computes the effectiveness of a system relative to its performance in reversible conditions. It is defined as the ratio of the thermal efficiency of an actual system compared to an idealized or reversible version of the system for heat engines. It can also be described as the ratio of the useful work output of the system to the reversible work output for work-consuming systems. For refrigerators and heat pumps, it is the ratio of the actual COP and reversible COP.
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After retirement, he spent several years as visiting professor at leading American universities. His research covered a very wide area: problems of exergy, evaporation, binary and multi-component systems, heat and mass transfer, combustion and gasification, high temperature plasma, solar collectors and irreversibility of energy conversion in thermodynamic processes. With M. Jakob he laid down principles of nucleate bubble growth in superheated liquid. His textbook Technische Thermodynamik, published in 1935 in Dresden, had seven improved and extended editions in Germany, and was translated into English (Technical Thermodynamics) and Russian (Tehnicheskaya termodinamika).
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Air can be passed over common, solid desiccants (like silica gel or zeolite) or liquid desiccants (like lithium bromide/chloride) to draw moisture from the air to allow an efficient mechanical or evaporative cooling cycle. The desiccant is then regenerated by using solar thermal energy to dehumidify, in a cost-effective, low-energy- consumption, continuously repeating cycle.San, J. Y., Lavan, Z., Worek, W. M., Jean-Baptiste Monnier, Franta, G. E., Haggard, K., Glenn, B. H., Kolar, W. A., Howell, J. R. (1982). "Exergy analysis of solar powered desiccant cooling system". Proc.
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Endoreversible thermodynamics is a subset of irreversible thermodynamics aimed at making more realistic assumptions about heat transfer than are typically made in reversible thermodynamics. It gives an upper bound on the energy that can be derived from a real process that is lower than that predicted by Carnot for a Carnot cycle, and accommodates the exergy destruction occurring as heat is transferred irreversibly. Endoreversible thermodynamics was discovered in simultaneous work by Novikov and Chambadal,Chambadal P (1957) Les centrales nucléaires. Armand Colin, Paris, France, 4 1-58 although sometimes mistakenly attributed to Curzon & Ahlborn.
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Summit Power Group is a Seattle-based energy development company, responsible for developing electric power plants and other energy-related facilities, which are primarily natural gas-fired and wind-powered, with solar power recently added. Summit does not develop conventional coal-fired power plants without carbon capture. Summit's prospective IGCC/CCS projects include the Texas Clean Energy Project, the Renewable Energy Corporation Project in Montana, and surface facilities for underground coal gasification (UCG) projects in the early stages of development by Laurus Energy as a licensee of Ergo Exergy.
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Thus, if a drastic CO2 emissions abatement of the transportation sector is pursued, a more intensive utilization of ethanol in the Brazilian transportation sector mix is advisable. However, as the overall exergy conversion efficiency of the sugar cane industry is still very low, which increases the unit energy cost of ethanol, better production and end-use technologies are required. Nonetheless, with the current scenario of a predominantly renewable Brazilian electricity mix, based on more than 80% of renewable sources, this source consolidates as the most promising energy source to reduce the large amount of greenhouse gas emissions which transportation sector is responsible for.
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Smaller compressors can approximate isothermal compression even without intercooling, due to the relatively high ratio of surface area to volume of the compression chamber and the resulting improvement in heat dissipation from the compressor body itself. When one obtains perfect isothermal storage (and discharge), the process is said to be "reversible". This requires that the heat transfer between the surroundings and the gas occur over an infinitesimally small temperature difference. In that case, there is no exergy loss in the heat transfer process, and so the compression work can be completely recovered as expansion work: 100% storage efficiency.
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An exergoeconomic assessment accounting for the total and non-renewable unit exergy costs and specific CO2 emissions of Brazilian electricity is performed by Flórez-Orrego et al. (2014), comprising thermal, nuclear, hydro, wind farms and biomass- fired power plants. The analysis starts from the fuel obtainment and continues through the different stages of construction, fuel transportation and processing, operation and decommissioning of the plant, with electricity generation as the desired output. This approach allows the calculation of direct CO2 emissions as well as the upstream and downstream emissions, which play an important role in some technologies.
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A multi-stage electrochemical hydrogen compressor incorporates a series of membrane-electrode-assemblies (MEAs), similar to those used in proton exchange membrane fuel cells; this type of compressor has no moving parts and is compact. The electrochemical compressor works similar to a fuel cell, a voltage is applied to the membrane and the resulting electric current pulls hydrogen through the membrane. With electrochemical compression of hydrogen, a pressure of 14500 psi (1000bar or 100MPa) is achieved. A patent is pending claiming an exergy efficiency of 70 to 80% for pressures up to 10,000 psi or 700 bars.
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According to the first law of thermodynamics, all energy inputs should be accounted with equal weight, whereas by the second law, diverse energy forms should be accounted for using different values. The conflict may be resolved in one of several ways: the value differences between the energy inputs might be ignored, a value ratio may be arbitrarily assigned (e.g., that an input joule of electricity is 2.6-times more valuable than a joule of heat or fuel), the analysis may be supplemented by economic/cost analysis, or exergy, a thermodynamic measure of the quality of energy, may be used as the metric for the LCA (instead of energy).
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The women's race, with its higher prize money, attracted a field led by two-time champion (and defending Olympic gold medalist) Kristin Armstrong of Team Exergy TWENTY12. In the race, American Rory Sutherland of won the first stage and stayed close in the others to win the men's title by 15 seconds over Chad Beyer of Competitive Cyclist Racing Team, while Armstrong won four of the five stages to win the women's title for the third time by a decisive 6:41 over Carmen Small. Surprisingly, the Bontrager-LiveStrong under-23 youth team, a remnant of the now-defunct Team RadioShack, took the top two places in the "Gila Monster" final stage with Lawson Craddock and Ian Boswell and won the men's team competition.
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Flash reactors can also be used in the drying section to quickly remove water content Cohce, M. K., Dincer, I. and Rosen, M. A. (2011), Energy and exergy analyses of a biomass-based hydrogen production system. Bioresource Technology 102(18): 8466-8474 from the biomass by injecting high velocity heated air which acts as a pretreatment to the actual pyrolysis reaction which also occurs in a flash reactor.Meier, D., van de Beld, B., Bridgwater, A. V., Elliott, D. C., Oasmaa, A. and Preto, F. (2013) State-of-the-art of fast pyrolysis in IEA bioenergy member countries. Renewable and Sustainable Energy Reviews 20 (0); 619-641 also shows that a flash reactor is used, after the grinding of the biomass, with the addition of extreme heat, into a mixture of bio-oil, char and ash.
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He was responsible for "out-of pile experiments" in the four-party agreement (France- Germany-Italy-England), from 1984 to 1990 and, subsequently, was Director of the "energetic Norms" Section, in the "Energy Saving" Division up to June 1995. In this latter period, as Consultant for the Italian Ministry of Industry for Energy Saving in Italy, he promoted the introduction (in ENEA) of advanced evaluation methodologies of Power Plants based on the physical quantities of Exergy and Emergy, and their corresponding micro and macro- economic Theories (Exergoeconomics and Emergoeconomics respectively). From June 1995 he worked in the "Engineering Division and Experimental Plants" as Project Manager of the so-called Integrated Multicriteria (Energetic- Exergetic-Emergetic-Economic) Approach. Since December 2001, as a member of the Technical-Scientific Unit termed as "Renewable Sources and Innovative Energetic Cycles", he has been dealing with evaluation methods of strategic options concerning both traditional and new alternative energy sources of "equipollent", such as hydrogen, for example.
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A natural gas integrated power & syngas (hydrogen) generation cycle utilizes semi-closed (sometimes called closed) gas turbine cycles where fuel is combusted with pure oxygen in a presence of the working fluid of the cycle which is a mix of combustion products CO2 and H2O (steam). The integrated cycle implies that, before combustion, methane (primer natural gas component) is mixed with working fluid and converted into syngas (mix of H2 and CO) in a catalytic adiabatic (without an indirect heat supply) reactor by using sensible heat of the hot working fluid leaving, in the simplest case, the gas turbine outlet. The largest part of produced syngas (about 75%) is directed into the combustion chamber of the gas-turbine cycle to generate power, but another part of syngas (about 25%) is withdrawn from the power generation cycle as hydrogen, carbon monoxide, or their blend to produce chemicals, fertilizers, synthetic fuels, etc. The thermodynamic benefit owing to this modification is substantiated by exergy analysis.
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Under floor radiant systems are evaluated for sustainability through the principles of efficiency, entropy, exergyAsada, H., Boelman, E.C., Exergy analysis of a low-temperature radiant heating system, Building Service Engineering, 25:197-209, 2004 and efficacy. When combined with high-performance buildings, underfloor systems operate with low temperatures in heating and high temperatures in coolingBabiak J., Olesen, B.W., Petráš, D., Low-temperature heating and high-temperature cooling – Embedded water-based surface systems, REHVA Guidebook no. 7, Forssan Kirjapaino Oy- Forssan, Finland, 2007 in the ranges found typically in geothermalMeierhans, R.A., Slab cooling and earth coupling, ASHRAE Transactions, vol. 99(2):511-518, 1993 and solar thermal systems. When coupled with these non-combustible, renewable energy sources the sustainability benefits include reduction or elimination of combustion and greenhouse gases produced by boilers and power generation for heat pumpsKilkis, B.I., Advantages of combining heat pumps with radiant panel and cooling systems, IEA Heat Pump Centre Newsletter 11 (4): 28-31, 1993 and chillers, as well as reduced demands for non-renewables and greater inventories for future generations.
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Fitzgerald, D. Does warm air heating use less energy than radiant heating? A clear answer, Building Serv Eng Res Technol 1983; 4; 26, Olesen, B.W., deCarli, M., Embedded Radiant Heating and Cooling Systems: Impact of New European Directive for Energy Performance of Buildings and Related CEN Standardization, Part 3 Calculated Energy Performance of Buildings with Embedded Systems (Draft), 2005, < > The greater efficiency of 'wire to water' versus 'wire to air' flow due to water's significantly greater heat capacity favors fluid based systems over air based systems. Both field application and simulation research have demonstrated significant electrical energy savings with radiant cooling and dedicated outdoor air systems based in part on the previous noted principles.Leach, M., Lobato, C., Hirsch, A., Pless, S., Torcellini, P., Technical Support Document: Strategies for 50% Energy Savings in Large Office Buildings, National Renewable Energy Laboratory, Technical Report, NREL/TP-550-49213, September 2010 In Passive Houses, R-2000 homes or Net Zero Energy buildings the low temperatures of radiant heating and cooling systems present significant opportunities to exploit exergy.
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