The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Framework Convention on Climate Change

Capture and sequestration of CO2 from fossil fuel power plants is gaining widespread interest as a potential method of controlling greenhouse gas emissions. Performance and cost models of an amine (MEA)-based CO2 absorption system for postcombustion flue gas applications have been developed and integrated with an existing power plant modeling framework that includes multipollutant control technologies for other regulated emissions. The integrated model has been applied to study the feasibility and cost of carbon capture and sequestration at both new and existing coal-burning power plants. The cost of carbon avoidance was shown to depend strongly on assumptions about the reference plant design, details of the CO2 capture system design, interactions with other pollution control systems, and method of CO2 storage. The CO2 avoidance cost for retrofit systems was found to be generally higher than for new plants, mainly because of the higher energy penalty resulting from less efficient heat integration as well ...

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A technical, economic, and environmental assessment of amine-based CO2 capture technology for power plant greenhouse gas control

Solar Engineering Of Thermal Processes

Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed. © 2011 Published by Elsevier Ltd.

A review of solar photovoltaic technologies

Feasibility study and design of a low-energy residential unit in Sagarmatha park for environmental impact reduction of high altitude buildings


 The waste heat recovery from the gas turbine (GT) exhaust is typical for increasing performance and reducing CO2 emissions in industrial facilities. Nowadays, numerous already operating gas turbine plants could be retrofitted and upgraded with a bottoming cycle powered by the exhaust gasses. In this case, the standard solution would be to use a water Steam Rankine Cycle. However, even if this technology usually yields the best efficiency, other alternatives are often preferred on the lower size scale. Organic Rankine Cycles (ORCs) are the commercial alternatives to Steam Rankine Cycles, but many other alternative cycles exist or can be developed, with potential benefits from safety, technical or economic points of view. This study compares several alternative technologies suited to recover gas turbine waste heat, and a detailed cost analysis for each is presented. On this basis, a guideline is proposed for the technology choice considering a wide range of application sizes and temperature levels typical for waste heat recovery from GTs gas turbines. The compared technologies are ORCs, Rankine Cycles (RCs) with water and ammonia mixtures at constant composition, supercritical CO2 cycles (sCO2), sCO2 cycles with mixtures of CO2, and other gasses. As it resulted, ORCs can achieve the lowest levelized cost of energy (32 $/MWh - 46 $/MWh) if flammable fluids can be employed. Otherwise, Rankine cycles with a constant composition mixture of water and ammonia are a promising alternative, reaching a Levelised Cost Of Energy (LCOE) of 36-58 $/MWh.

Techno-Economic Comparison of Several Technologies for Waste Heat Recovery of Gas Turbine Exhausts

This paper presents the state of the art and the perspectives of the use of molten carbonate fuel cells with renewable energy sources. The molten carbonate fuel cell is the only technology that can use fuels containing carbon monoxide and carbon dioxide in the anode gas. It has been even shown in experimental tests in single cells that carbon monoxide can be considered as a fuel in this type of fuel cell. The fuels that can be used in MCFC are landfill gas, biogas from anaerobic digestion processes and syngas from gasification of biomass and waste. The commercial size of MCFC stacks (125 to 250 kW) is the right size for use with such fuels which are generally not available for power plants with output larger than some MW. All the above fuels are characterized by the presence of contaminants that need be removed before their use in the fuel cell. Among the contaminants hydrogen sulfide and chlorine compounds seem to cause the worst damage. To be used with such fuels, MCFC still need to be deeply investigated and duration tests are needed to determine the highest tolerable concentrations in the anode gases.Copyright © 2003 by ASME

Perspectives on the Use of Molten Carbonate Fuel Cells with Renewable Energy Sources

Integrating large shares of renewables into energy systems requires energy storage technologies able to efficiently dispatch and convert different energy vectors at a local level (multi-energy storage). The paper investigates the performance of multi-energy storage based on the Thermally Integrated Pumped Energy Storage (TIPTES) technology. TIPTES stores electric energy as thermal exergy at temperatures higher or lower than the environment but also exploits additional low-temperature thermal sources, commonly from renewables or waste heat recovery, to boost the charging or discharging phases. In the paper, two different multi-energy TIPTES (mTIPTES) systems are modelled and simulated in three residential case studies where electric and thermal vectors are present, together with solar electric and thermal production. The mTIPTES annual operation is optimised via mixed-integer linear programming, linearising the operating characteristics of mTIPTES components (heat pumps, chillers, organic Rankine cycles and thermal energy storage). Finally, mTIPTES was compared against lithium-ion batteries, a benchmark for residential energy storage. The comparison is based on thermodynamic and economic figures, with the mTIPTES capital cost estimated based on cost models from the literature. The results showed that mTIPTES perform better than the battery from a thermodynamic point of view, reducing the curtailment of renewables. In economic terms, for large penetrations of renewables, this translated into an operating cost reduction of up to around 15 % compared to a system without storage, which is five percentage points lower than what was achieved with batteries. Similar results were found for CO2 emissions and primary energy consumption, for which reductions larger than batteries and up to 20 %, compared to a case without storage, can be found. Despite the operating cost reduction, the mTIPTES total annualised cost (including capital costs) is around double compared to BES, and, for the investigated configurations, mTIPTES could not achieve financial feasibility. 

Thermally integrated pumped thermal energy storage for multi-energy districts: Integrated modelling, assessment and comparison with batteries


 The recent spreading of the interest for fuel cells brings, as a consequence, the need of intense effort for components and system development and testing. While the most resourceful cell developers have realized experimental set-ups for cell duration estimation, it is very rare to find test rigs for complete characterization of cell performance as a function of the numerous input parameters i.e. streams mass flow, composition, temperature and purity, fuel utilization factor, current density. In the present state of the art some modelling of the influence of these factors exists as well as some experimental results for cell potential evaluation at different current densities. What is not found in literature and is difficult to obtain is a complete experimental characterization of fuel cells in which the dependence of performances on a single factor is disaggregated from the others and clearly evaluated. This paper present a test rig for single cell designed to reach these targets and its first tests on a Molten Carbonate Fuel Cell. The experimental setup has revealed to be very flexible allowing the characterization of the system at different operating conditions.

Umberto Desideri

Papers

Feasibility study and design of a low-energy residential unit in Sagarmatha park for environmental impact reduction of high altitude buildings

Techno-Economic Comparison of Several Technologies for Waste Heat Recovery of Gas Turbine Exhausts

Perspectives on the Use of Molten Carbonate Fuel Cells with Renewable Energy Sources

Thermally integrated pumped thermal energy storage for multi-energy districts: Integrated modelling, assessment and comparison with batteries

Design, Construction, Start-Up and First Experimental Trials of a Test Rig for Single Fuel Cells