Amount Of Useful Energy Research Articles

Energy Recovery from Acid–Base Neutralization Process through pH-Sensitive Polymeric Ion Exchangers

Globally speaking, waste acid neutralization is a widely used industrial pollution control process. In principle, acid–base neutralization is a thermodynamically favorable reaction that involves the association of hydrogen and hydroxyl ions to form neutral water molecules with the generation of a significant amount of thermal energy (ΔH = −55.84 kJ/mol). However, it is not possible to recover the energy, because the increase in temperature of the bulk solution phase is often miniscule, because of the diluted nature of the waste acid solution and the high specific heat of water. Here, we demonstrate a methodology to recover a significant amount of useful energy by carrying out the neutralization reaction inside a pH-sensitive hydrophilic polymer (or biopolymer) phase containing covalently attached weak-acid or weak-base functional groups. When contacted with an acid or a base, the variation of pH causes the functional groups to reversibly acquire and lose its ionic character. This gives rise to an on–off pattern regarding the generation of osmotic pressure inside the polymer phase, causing it to reversibly swell and shrink, because of the movement of water into and out of the polymer phase. Laboratory experiments validate the reversibility of the swelling–shrinking pattern of a commercial weak-acid ion-exchange resin for multiple numbers of cycles with a concomitant generation of mechanical energy during the neutralization reaction. The process can be enhanced by tailoring the cross-linking and hydrophilicity of the polymer phase. The energy generated is free of carbon emission.

Comment on ‘Quantum Friction—Fact or Fiction?’

If quantum friction existed (Pendry 2010 New J. Phys.12 033028) an unlimited amount of useful energy could be extracted from the quantum vacuum and Lifshitz theory would fail. Both are unlikely to be true.

MODEL PREDICTIVE CONTROL OF A CATALYTIC FLOW REVERSAL REACTOR WITH HEAT EXTRACTION

This paper presents the formulation of a controller for a Catalytic Flow Reversal Reactor (CFRR) with heat extraction. The controller is based on the Model Predictive Control (MPC) concept. The MPC scheme uses a model that assumes plug flow and neglects radial gradients in the reactor but accounts for the two phases within the reactor. The prediction of the future output behavior from the model is obtained by using the Method of Characteristics as proposed by Shang et al. (2004) for convection dominated distributed parameter systems. The formulated controller is applied to a CFRR unit for the catalytic oxidation of fugitive lean methane mixtures. The objective of the control algorithm is to maintain stable reactor operation, while extracting the maximum amount of useful energy by hot gas removal from the mid-section of the reactor. Simulations are used to show the performance of the designed controller.

Automated dosimetry using radiation sensitive films and validation of routine dosimetry data

The nutritional value of food and its environmental impact have received considerable attention, however an assessment of environmental sustainability of catered meals is lacking. We therefore assessed the nutritional value and resource consumption of a specific catered meal, pork tenderloin with potato croquettes, carrots and mushroom sauce (‘Canteen Pork’). The outcomes are compared with that of an identical meal cooked at home (‘Home’), for which ‘Low’ and ‘High’ scoring hypothetical alternatives were defined (e.g. whether or not frying oil as a waste product was reprocessed or recycled), as well as with that of a vegetarian alternative: Quorn™. The resource consumption impact is assessed from cradle-to-disposal, expressed as the Cumulative Exergy Extraction from the Natural Environment (CEENE). Exergy is the amount of useful energy. The CEENE approach accounts for all resource types and is unique since it considers the deprived natural net primary production (expressed in exergy) as the impact for human land occupation, highly relevant for crop and thus food production. The food production, processing and packaging stage accounts for the largest amount of resource consumption compared to food preparation and waste management. The ‘Home Pork High’ scenario has the highest resource consumption at 83 MJex meal−1. ‘Home Pork Low’, ‘Home Quorn™ High’, ‘Canteen Pork’, ‘Home Quorn™ Low’ and ‘Canteen Quorn’ have a 15, 18, 26, 32 and 40% lower resource consumption compared to ‘Home Pork High’, respectively. For all scenarios, biomass resources contribute 52–64% of the total CEENE, mainly through land occupation. The nutritional analysis, via nutritional density scoring (the higher the better), resulted in a score of 18.1 and 31.2 for the ‘Home Quorn Low’ and ‘High’, 10.4 and 23.4 for the ‘Home Pork High’ and ‘Low’ scenario and 17.0 and 27.3 for the ‘Canteen Pork’ and ‘Canteen Quorn™’, respectively. To conclude, the vegetarian meal scores best on both attributes, however, this effect diminishes considerably if one considers outcomes per energy or protein amount. With regards to catered vs home cooked meals, resource consumption is lower in canteen prepared meals than in the case of the home-cooked meal. However, the nutritional value can be lower or higher depending on consumer behaviour, namely the extent of the use, type and application of butter is key in altering this result.

Geothermal energy from hot dry rock: A renew able energy technology moving towards practical implementation

The technology to extract useful amounts of energy from the large, ubiquitous, hot dry rock (HDR) resource has been under development for more than twenty years. Initial work during the 1970's and 1980's showed that it is possible to access and extract HDR energy using techniques originally conceived and tested by the Los Alamos National Laboratory. The process entails drilling a well deep enough to reach hot rock, injecting water at high enough pressure to open natural joints in the rock, and returning the water, heated by the rock, to the surface through one or more additional wellbores. After extraction of its thermal energy, the water is recirculated through the hot rock to mine more heat. In this closed-loop process, nothing is released to the environment except heat, and no long-term wastes accumulate. The practical potential of HDR technology was demonstrated in a series of flow tests conducted from 1992 to 1995 at the HDR pilot facility at Fenton Hill, NM. These tests showed that energy can be extracted from HDR in significant amounts over extended time periods. Extensive analyses and reservoir characterization studies carried out as part of the testing program provided a large amount of information about the dynamics of the heat extraction process and confirmed that HDR energy production facilities can be operated with minimal environmental effects. Operating strategies evaluated during the test period included the production of energy at steady-state levels for extended periods and on a variable-output schedule particularly suited to load-following electricity generation.

Energy quality and energy surplus in the extraction of fossil fuels in the U.S.

The goal of net energy analysis is to assess the amount of useful energy delivered by an energy system, net of the energy costs of delivery. The standard technique of aggregating energy inputs and outputs by their thermal equivalents diminishes the ability of energy analysis to achieve that goal because different types of energy have different abilities to do work per heat equivalent. This paper describes physical and economic methods of calculating energy quality, and incorporates economic estimates of quality in the analysis of the energy return on investment (EROI) for the extraction of coal and petroleum resources in the U.S. from 1954 to 1987. EROI is the ratio of energy delivered to energy used in the delivery process. The quality-adjusted EROI is used to answer the following questions: (1) are coal and petroleum resources becoming more scarce in the U.S.?, (2) is society's capability of doing useful economic work changing?, and (3) is society's allocation of energy between the extraction of coal and petroleum optimal? The results indicate that petroleum and coal became more scarce in the 1970s, although the degree of scarcity depends on the type of quality factor used. The quality-adjusted EROI shed light on the coal-petroleum paradox: when energy inputs and outputs are measured in thermal equivalents, coal extraction has a much larger EROI than petroleum. The adjustment for energy quality reduces substantially the difference between the two fuels. The results also suggest that when corrections are made for energy quality, society's allocation of energy between coal and petroleum extraction meets the efficiency criteria described by neoclassical and biophysical economists.

Thermodynamics of energy extraction from fractured hot dry rock

It has been proposed to extract energy from the subterranean hot dry rock bed (HDR) by creating one or more narrow fractures in the rock and circulating cold water through the fractures. In time, the temperature of the rock region surrounding the crack drops under the influence of time-dependent conduction. This study presents the most basic thermodynamic aspects (first law and second law) of the HDR energy extraction process. It shows which parameters most influence the amount of useful energy (exergy) extracted from the HDR reservoir over a fixed time interval. For example, the water flow rate can be selected optimally in order to maximize the delivery of energy over the lifetime of the HDR system.

Status Review and Prospects for Solar Industrial Process Heat (SIPH)

Application of solar energy to supply industrial process heat is attractive because industry needs a continuous supply of energy at temperature levels well suited to both current and developing solar equipment. Solar energy systems provide industrial users with a nonpolluting alternative to fossil fuels that is immune to increasing costs and uncertain future supplies. Careful design and analysis are necessary to determine suitable applications for solar energy in industry. Solar systems and components are presently available for process hot air, hot water, and steam applications at temperatures up to about 300/sup 0/C and systems operating at temperatures up to about 1000/sup 0/C are approaching commercial readiness. Cogeneration could then also become a viable option. Field tests conducted in different parts of the world have provided information needed to improve the design, operation, and performance of future solar IPH systems. In every case, matching between the solar system and the industrial process was found to be important to the amount of useful energy that a solar system can deliver.

Second Law Analysis and Synthesis of Solar Collector Systems

The second law of thermodynamics is used to analyze the potential for exergy conservation in solar collector systems. It is shown that the amount of useful energy (exergy) delivered by solar collector systems is affected by heat transfer irreversibilities occurring between the sun and the collector, between the collector and the ambient air, and inside the collector. Using as working examples an isothermal collector, a nonisothermal collector, and the design of the collector-user heat exchanger, the optimum operating conditions for minimum heat transfer irreversibility (maximum exergy delivery) are derived.

Improvement of Silicon Solar Cell Performance Through the Use of Thin Film Coatings

Thin film coatings are used universally in solar cell power systems for spacecraft. Antireflective coatings are used to increase the amount of useful energy reaching the active surface of the cell. Multilayer interference filters are employed to reject unwanted portions of the solar spectrum in order to reduce equilibrium temperature and to prevent ultraviolet damage. Glass covers are used in conjunction with these coatings for the purpose of increasing the thermal emittance of the surface. Appreciable performance increases can be obtained through the uses of these filters and coatings.