Heating Company Lake George, Queensbury, Saratoga, Albany NY

NASA Report: Greenhouse Gases, Not Sun, Driving Warming (LiveScience.com)

David Sellers — Fri, 03 Feb 2012 17:26:05 +0000

LiveScience.com – A recent, prolonged lull in the sun’s activity did not prevent the Earth from absorbing more solar energy than it let escape back into space, a NASA analysis of the Earth’s recent energy budget indicates. nbsp; David Sellers Mechanical Inc.175 Broad Street Suite 168 Glens Falls, NY, 12801 USA rebekah@davidsellers.com •&nbsp518-623-9760

Salazar, Chu Flip Switch on 65% Energy Savings

David Sellers — Fri, 03 Feb 2012 17:26:04 +0000

a rel=nofollow class=title-linkspanSalazar, Chu Flip Switch on 65% Energy Savings/span/adiv class=field field-name-body field-type-text-with-summary field-label-hiddendiv class=field-itemsdiv class=field-item evenpEnergy-Efficient LED Lights Illuminated in Ceremony on National Mall/p
/div/div/div

Theoretical and practical analysis of an integrated solar hot water-powered absorption cooling system

David Sellers — Wed, 01 Feb 2012 22:03:47 +0000

Publication year: 2012brbSource:/b Energy, Available online 31 January 2012brJ. Darkwa, S. Fraser, D.H.C. ChowbrEvaluation of a typical integrated solar absorption cooling system has been carried out to determine its overall performance. Analysis of the results revealed an operational efficiency of 61% for the solar collectors at a mean differential temperature (ΔT) of 51 °C as compared with the manufacturer’s rating of 70% at a ΔTof 60 °C. The absorption chiller did however perform quite satisfactorily and achieved a coefficient of performance (COP) of 0.69 as compared with the manufacturer’s rating of 0.7 despite the slight deviation at the collectors end. The installation strategy for the hot water storage tanks also appears to have achieved its objective of maintaining controlled temperature stratification in the tanks. It could therefore be concluded that the system has proved its potential as a viable cooling technology for application in buildings. However, in order to maintain appropriate hot water supply temperature during low solar radiation levels, supplementary heat source such as gas or biomass fired system would have to be considered and incorporated into solar absorption cooling systems.brh3 class=h3Highlights/h3► The theoretical collector efficiency was obtained as 69%. ► The practical or operational collector efficiency was obtained as 61%. ► The absorption chiller achieved a coefficient of performance (COP) of 0.69 as compared with the manufacturer’s rating of 0.7.

A method to determine the power to heat ratio, the cogenerated electricity and the primary energy savings of cogeneration systems after the European Directive

David Sellers — Tue, 31 Jan 2012 00:24:08 +0000

Publication year: 2012brbSource:/b Energy, Available online 29 January 2012brChristos A. FrangopoulosbrAccording to the European Directive for the promotion of cogeneration, in order for cogeneration systems to be eligible for economic and financial benefits, they must comply with certain requirements regarding efficiency and primary energy savings. Therefore, the calculation of these two performance indicators, together with the electrical and/or mechanical energy produced in connection with the useful heat, is of crucial importance for the economic viability of these systems. In the present work, the main questions that have to be answered on this subject are posed, and a complete procedure to answer the questions and perform the necessary calculations is presented. This work not only is useful for the current needs, but also gives specific hints for future revision of the Directive on Cogeneration and the related texts.brh3 class=h3Highlights/h3► Definitions given in the European Directive for cogeneration are clarified. ► A method to calculate primary energy savings of CHP systems is presented. ► The method determines also the cogenerated electricity from CHP systems. ► The method is extended to trigeneration systems.

City of Houston Joins Better Buildings Challenge, Partners with Energy Department to Reduce Energy Waste and Boost Efficiency

David Sellers — Sun, 29 Jan 2012 17:22:06 +0000

a rel=nofollow class=title-linkspanCity of Houston Joins Better Buildings Challenge, Partners with Energy Department to Reduce Energy Waste and Boost Efficiency /span/adiv class=field field-name-body field-type-text-with-summary field-label-hiddendiv class=field-itemsdiv class=field-item evenpWashington, D.C. — Building on President Obama’s call in the State of the Union address earlier this week for a new era for American energy, U.S. Energy Secretary Steven Chu joined with Houston Mayor Annise Parker today to announce that Houston, Texas is joining the Better Buildings Challenge. Houston is the latest community to join the Challenge, a public-private partnership that seeks to improve energy efficiency 20 percent by 2020 in commercial, government, and school buildings across the country./p/div/div/div

Energy Department Announces Student Teams, New Location for Solar Decathlon 2013

David Sellers — Sun, 29 Jan 2012 17:22:05 +0000

a rel=nofollow class=title-linkspanEnergy Department Announces Student Teams, New Location for Solar Decathlon 2013/span/adiv class=field field-name-body field-type-text-with-summary field-label-hiddendiv class=field-itemsdiv class=field-item evenpU.S. Department of Energy Secretary Steven Chu announced the 20 collegiate teams selected to compete in the U.S. Department of Energy Solar Decathlon 2013 and unveiled the competition’s location, the Orange County Great Park in Irvine, California./p
/div/div/div

Optimum design of district heating: Application of a novel methodology for improved design of community scale integrated energy systems

David Sellers — Fri, 27 Jan 2012 23:29:27 +0000

Publication year: 2012brbSource:/b Energy, Available online 26 January 2012brSayyed Mohammad Sanaei, Toshihiko NakatabrThe purpose of this paper is to present a new tool for design of integrated energy systems. The initial choice of the energy system components and the way they should interact is a crucial decision which the outcome of the design heavily relies on. Use of a physical law (instead of engineering judgment) as the basis of the decision making is the main advantage of the proposed approach over conventional approaches for design of community scale energy systems. The methodology has been implemented for design of a district heating system for an existing district in arid region of Iran. The optimum level of interaction between the energy system components has been identified by employing an optimization algorithm seeking to minimize the overall cost of the energy system. Some of the relative merits of the optimum design comparing to the present energy system are 17% increase of the exergy efficiency, 10.8% reduction in the amount of CO2production per capita and 2% reduction in overall energy related costs.brh3 class=h3Highlights/h3► We propose a novel tool for design of integrated energy systems. ► Proposed tool has the advantage of using a physical principle (exergy matching) to define the design scenarios. ► Optimum design of district heating system was found subject to variations in energy prices and heating devices’ efficiencies. ► Contrary to energy efficiency, exergy efficiency clearly points out the design with best energetic performance. ► Exergy optimum design becomes the feasible option as the energy prices tend to rise towards the international prices.

Methodology for maximising the use of renewables with variable availability

David Sellers — Fri, 27 Jan 2012 23:29:27 +0000

Publication year: 2012brbSource:/b Energy, Available online 24 January 2012brAndreja Nemet, Jiří Jaromír Klemeš, Petar Sabev Varbanov, Zdravko KravanjabrA problem when exploiting renewable energy sources, such as wind and solar radiation, is their fluctuating availability. In the presented work, the Heat Integration methodology for batch processes based on Time Slices has been extended to cover the integration of solar thermal energy, thus allowing for dealing with such variations. A procedure for identifying the number and durations of Time Slices for a problem featuring variable renewable energy supply has been formulated, and developed for solar energy utilisation. The main procedural steps involve partitioning of the measured/forecasted heat availability profile using a large number of candidate time boundaries, and then approximating it by a piecewise-constant profile using high-precision. The approximation profile is obtained by subjecting the candidate superset of time-boundaries to MILP optimisation, thus minimising integral inaccuracy compared to the forecasted availability profile. The Time Slice definitions are completed by approximating the heat loads within the Time Slices. The integration of solar thermal energy can be performed for the specified Time Slice, after the optimal number of Time Slices with approximated constant load has been selected. Using heat storage, the heat can be transferred between Time Slices.

An energetic analysis of CO2capture on a gas turbine combining flue gas recirculation and membrane separation

David Sellers — Fri, 27 Jan 2012 17:20:17 +0000

Publication year: 2012brbSource:/b Energy, Available online 24 January 2012brBouchra Belaissaoui, Gilles Cabot, Marie-Sophie Cabot, David Willson, Eric FavrebrPost-combustion Carbon Capture and Storage (CCS) is currently intensively investigated as a key issue for the mitigation of greenhouse gases emissions. A very large number of studies is dedicated to coal power plants. In this paper, the possibility to achieve carbon capture on a gas turbine, based on a combination of flue gas recycle and membrane separation is reported. Membrane processes are effectively known to offer attractive performances in terms of energy efficiency, as soon as concentrated and/or pressure mixtures have to be treated. Two different flow schemes have been simulated and compared: flue gas recycle with air combustion and flue gas recycle with an oxygen enriched feed mixture. The energy requirement of the different processes, expressed in GJ (thermal basis) per ton of recovered CO2, and the size of the membrane capture process (expressed in mof membrane area) have been systematically estimated for different membrane separation performances. It is shown that an overall energy requirement down to 2.6 GJ per ton can possibly be achieved when optimal operating conditions, based on oxygen enriched air (OEA) combustion together with a highly selective membrane (CO2/N2selectivity of 200) are combined. Additional possibilities in order to minimise the energy penalty of the process are discussed.brh3 class=h3Highlights/h3► A carbon capture process for gas turbine has been investigated for the first time, with membrane separation unit. ► Air combustion systematically induces CO 2 capture specific energy requirement far above alternative capture processes. ► Remarkably, a very low energy requirement can be achieved (down to 2.6 GJ/ton) with Oxygen Enriched Air combustion. ► Target membrane selectivities and optimal oxygen content for combustion have been identified.

Exergy and economic analysis of a pyramid-shaped solar water purification system: Active and passive cases

David Sellers — Fri, 27 Jan 2012 17:20:17 +0000

Publication year: 2012brbSource:/b Energy, Available online 23 January 2012brAli Kianifar, Saeed Zeinali Heris, Omid MahianbrAn exergy analysis has been conducted to show the effect of a small fan on the exergy efficiency in a pyramid-shaped solar still. The tests were carried out in Mashhad (36° 36′ N), for two solar still systems. One of them was equipped with a small fan (active system), to enhance the evaporation rate while the other one was tested in passive condition (no fan). To examine the effects of radiation and water depth on exergy efficiency, experiments in two seasons and two different depths of water in the solar still basin were performed. The results show that during summer, active unit has higher exergy efficiency than passive one while in winter there is no considerable difference between the exergy efficiency of the units. Results also reveal that the exergy efficiency is higher when the water depth in the basin is lower. Finally, the economic analysis shows a considerable reduction in production cost of the water (8–9%) when the active system is used.brh3 class=h3Highlights/h3► Using a small fan in the solar still; reduces the productive cost of fresh water up to 9%. ► Effects of the fan and basin depth on the exergy efficiency during summer and winter were examined. ► Utilizing an active system will increase the daily productivity of fresh water by 20%.