MW Scale Research Articles

Flexible charging time and geography independent dual thermal cycle based energy storage

Share of renewable energy for electrical energy is increasing every year. Major part of the renewable energy such as solar and wind energy are intermittent and fluctuating. Pumped Hydro technique and compressed air energy storage (CAES) technique are proven technologies for MW scale but they are highly geography dependent. A new concept of energy storage is discussed in this paper which is site independent and flexible charging time. In this concept, there are two thermal cycles; one is charge cycle which is used to store energy and discharge cycle which is used to generate electricity from stored energy. A charge cycle works based on the closed loop heat pump principle. Discharge cycle is an organic Rankine cycle which utilises stored heat and produces electricity. This concept has a major advantage of hybridising charge cycle with any waste low grade heat for improving COP and overall round trip efficiency.

A free wake vortex lattice model for vertical axis wind turbines: Modeling, verification and validation

Since the 1970s several research activities had been carried out on developing aerodynamic models for Vertical Axis Wind Turbines (VAWTs). In order to design large VAWTs of MW scale, more accurate aerodynamic calculation is required to predict their aero-elastic behaviours. In this paper, a 3D free wake vortex lattice model for VAWTs is developed, verified and validated. Comparisons to the experimental results show that the 3D free wake vortex lattice model developed is capable of making an accurate prediction of the general performance and the instantaneous aerodynamic forces on the blades. The comparison between momentum method and the vortex lattice model shows that free wake vortex models are needed for detailed loads calculation and for calculating highly loaded rotors.

Economics of WtE

Waste-to-energy (WtE) economics are resulting from biogas-fueled fuel cells that can generate multiple revenue streams at MW scale. Part II of this feature looks at other companies keen to demonstrate their technologies in this application.

Burrowing energetics of the Giant Burrowing Cockroach Macropanesthia rhinoceros: An allometric study

Burrowing is an important life strategy for many insects, yet the energetic cost of constructing burrows has never been studied in insects of different sizes. Open flow respirometry was used to determine the allometric scaling of standard metabolic rate (MRS) and burrowing metabolic rate (MRB) in the heaviest extant cockroach species, the Giant Burrowing Cockroach Macropanesthia rhinoceros, at different stages of development. At 10°C, MRS (mW) scales with body mass (M; g) according to the allometric power equation, MRS=0.158M0.74, at 20°C the equation is MRS=0.470M0.53, and at 30°C the equation is MRS=1.22M0.49 (overall Q10=2.23). MRS is much lower in M. rhinoceros compared to other insect species, which is consistent with several aspects of their life history, including flightlessness, extreme longevity (>5years), burrowing, parental behaviour, and an energy-poor diet (dry eucalypt leaf litter). Energy expenditure during burrowing at 25°C scales according to MRB=16.9M0.44, and is approximately 17 times higher than resting rates measured at the same temperature, although the metabolic cost over a lifetime is probably low, because the animal does not burrow to find food. The net cost of transport by burrowing (Jm−1) scales according to NCOT=120M0.49, and reflects the energetically demanding task of burrowing compared to other forms of locomotion. The net cost of excavating the soil (Jcm−3) is statistically independent of body size.

New magnitude scales M L and spectrum-based M w for the area around Shanxi Rift System, North China

A new locally calibrated M L scale was derived for the area around the Shanxi rift system, North China, from 83 events recorded on 56 stations of the Shanxi Seismic Network (SSN) resulting in 2,633 observations during the period of 2008–2012. It is expressed as M L = log(A) + 0.80log(R) + 0.00187R − 1.4, where A is the maximum amplitude of vertical component in nanometer (nm) measured on a simulated Wood–Anderson seismogram at a hypocentral distance R. The new M L scale is valid for distances up to 600 km and is an improvement comparing to the currently used SSN scale, with a reduction in variance of 39 % in magnitude residuals. The moment magnitude M w was also calculated for the whole data set based on spectral analysis. To validate the Q-function used for spectral M w, we carried out moment tensor inversion for 17 moderate size events and selected the regional attenuation model which gave spectral M w on average closest to moment tensor M w. The most appropriate Q-function was found to be Q(f) = 299.4f 0.563. The determination of the M w magnitudes makes it possible to derive a relationship between the M L and M w scales of this region, which is expressed as M w = 0.85M L + 0.58, similar to relationships found elsewhere for similar tectonic environments.

Waste-to-energy projects get down and dirty by scavenging waste to score hydrogen: Part 2

Recent, promising waste-to-energy (WtE) economics are resulting from biogas-fueled fuel cells that can generate multiple revenue streams at MW scale. In the second, concluding part of this article, we look at other companies keen to demonstrate their technologies in this application, such as the alkaline fuel cell technology of AFC Energy, and the fuel cell powered materials handling fleet at BMW Manufacturing Co in South Carolina.

Recent developments of the Middle East catalog

This article summarizes a recent study in the framework of the Global Earth model (GEM) and the Earthquake Model of the Middle East (EMME) project to establish the new catalog of seismicity for the Middle East, using all historical (pre-1900), early and modern instrumental events up to 2006. According to different seismicity, which depends on geophysical, geological, tectonic, and seismicity data, this region is subdivided to nine subregions, consisting of Alborz–Azerbaijan, Afghanistan–Pakistan, Saudi Arabia, Caucasus, Central Iran, Kopeh–Dagh, Makran, Zagros, and Turkey (Eastern Anatolia; after 30° E). After omitting the duplicate events, aftershocks, and foreshocks by using the Gruenthal method, and uniform all magnitude to Mw scale, 28,244 main events remain for the new catalog of Middle East from 1250 B.C. through 2006. The magnitude of completeness (Mc) was determined as 4.9 for five out of nine subregions, where the least values of Mc were found to be 4.2. The threshold of Mc is around 5.5, 5.0, 4.5, and 4.0, for the time after 1950, 1963, 1975, and 2000, respectively. The average of teleseismic depths in all regions is less than 15 km. Totally, majority of depth for Kopeh–Dagh and Central Iran, Zagros, and Alborz–Azerbaijan, approximately, is 15, 13, and 11 km and for Afghanistan–Pakistan, Caucasus, Makran, Turkey (after 30° E), and Saudi Arabia is about 9 km.

Waste-to-energy projects get down and dirty by scavenging waste to score hydrogen: Part 1

Fuel cell manufacturers worldwide have been examining waste-to-energy applications (WtE, also referred to as EfW, energy from waste, and more specifically hydrogen from waste) since the early 1990s. During that time, proton-exchange membrane (PEMFC), alkaline (AFC), molten carbonate and direct carbonate (MCFC/DFC), solid oxide (SOFC), and phosphoric acid fuel cells (PAFC) have been demonstrated. Recent, promising WtE economics are resulting from biogas-fueled fuel cells that can generate multiple revenue streams at MW scale. In this first of a two-part article, we look at the practicalities of bioH2 for fuel cells, and look at how FuelCell Energy is showing this can certainly be done.

Solugas – Operation Experience of the First Solar Hybrid Gas Turbine System at MW Scale

CSP hybridisation is one of the most promising concepts for cost reduction and dispatchability, and also one of the most competitive with conventional electricity generation systems. The Solugas project, first solar hybrid system topped with a gas turbine at megawatt scale, was commissioned in May 2012 in Abengoa's Solúcar Platform near Seville.Numerous operation objectives of the project have been tackled since the operation started and the project is running for several hundred solar operation hours already, yet for the technology assessment the stable operation and evaluation of long time behaviour are crucial. In 2012 the maximum receiver outlet temperature objective was achieved: the temperature of the heat transfer medium -pressurised air- has been heated up to 800°C in one receiver, reaching a temperature gradient of almost 500K.Current objectives include obtaining the tubular receiver efficiency accurately and optimisation of plant operation and control, in order to be able to characterise the behaviour of the plant and the production of the future plants.

Dynamic Behaviour CO2 Capture and Compression: An Assessment

A clear understanding of the dynamic behavior of the whole chain of conventional power generation to CO2 storage is necessary. The rapidly increasing share of renewable energy makes the energy delivered to the grid more fluctuating leading to an impact on the CCS chain as well. A 250 MW scale carbon capture plant with CO2 compression has been modelled with Dymola (dynamic) and with Aspen Plus (steady-state). It is evident that large perturbations in flue gas flow rate will make it difficult to control the water balance. Moreover, parallel compression trains may be necessary to prevent compressors to run in spill back mode.

Research on Joint Power and Loads Control for Large Scale Directly Driven Wind Turbines

Emphasis of this article is on the dynamic characteristics analysis of individual pitch control for MW scale directly driven wind turbines with permanent magnet synchronous generator (PMSG). The pitch control objectives were analyzed and the objective expressions were deduced, including power expression, loads expression, and vibration expressions of blade and tower. Then, both the collective pitch control aiming at power control and the individual pitch control strategy aiming at joint power and loads control were analyzed, too. The blade root bending moments and the actual capture power of wind rotor were employed to be the control variables. The power was calculated based on the conventional measured parameters of wind turbines. In order to reflect the difference between the pitch angle command value and the actual value, the pitch actuator dynamic model was used. The research results show that both the collective pitch control strategy and the proposed individual pitch control strategy can effectively control the power injected into grid; moreover, the individual pitch control can reduce fatigue loads; while in the process of individual pitch control, the actual variation of blade pitch angle is closely related to not only the inflow speed but also the blade azimuth angle; individual pitch control strategy can reduce the variation amplitude of flapwise moments, but has little influence on the edgewise moments.

Seismic hazard assessment of Kashmir and Kangra valley region, Western Himalaya, India

A complete earthquake catalogue of the Western Himalaya (latitudes 30°N–36°N and longitudes 72°E–78°E) for the period of 1501–2010 has been compiled with earthquake magnitude computed in moment magnitude (Mw) scale. Pre- and early twentieth century records of earthquake damage have been documented from rare and out of print publications. Seismotectonics and seismic hazard for Kohistan arc, Kashmir–Hazara Syntaxis, Nanga-Parbat (Western Syntaxis), Karakoram and Himachal Himalaya are discussed with special reference to 1905 Kangra and 2005 Muzaffarabad earthquakes. Analyses of spatio-temporal variation in b-value from the region indicate significant precursor prior to the 2005 Muzaffarabad earthquake; progressive rise of background b-value observed and the main shock locates close to relative high b-value domains. Regions surrounding the location of the 1905 Kangra earthquake also display such high b-value for the period of 2005–2010 that calls for closer scrutiny. Temporal analysis of b-value from the epicentral block of Muzaffarabad earthquake clearly showed a high–low b-value couplet of 1.45–0.72, which may be treated as a typical precursor before an imminent large earthquake. Gumbel extreme value statistics indicate probability of occurrence of an event of Mw > 7.0 within 50 years in the region.

Modeling pilot plant results for CO2 stripping using piperazine in two stage flash

Piperazine (PZ) has shown good potential for use as a solvent for CO2 absorption in post-combustion carbon capture It has a high absorption rate good capacity and very good resistance to thermal and oxidative degradation . Thermodynamic and kinetic models for PZ-CO2-water have been developed in Aspen Plus® . Pilot scale experiments were conducted on a 0.1 MW scale at the Separations Research Program at UT Austin to demonstrate the performance of concentrated (8 m) PZ using an intercooled absorber and a two-stage flash. This paper describes modeling and simulation of CO2 stripping from PZ using data from two pilot campaigns conducted in Winter and Fall 2011.Vapor liquid equilibrium equations and thermodynamic models for this system were validated using pilot plant data and found to satisfactorily represent the actual operating conditions. Rigorous reconciliation was done on Fall 2011 data using Aspen Plus® Data Fit. The only major systematic adjustments were found in the CO2 measurements, which required 1.2 to 6.9% increase to match the predicted model values.The best equivalent work was 45.5kJ/mol CO2 in Winter 2011 and 36.6kJ/mol CO2 in Fall 2011. The validated model predicted that the pilot plant stripper configuration should be able to achieve 32.6kJ/mol at its optimum operating conditions. Major parameters that affected pilot plant performance were low values of rich loading and non-optimal operation of lean loading and cold rich bypass. Optimized values of operating conditions at 0.4 rich loading were identified as 0.31 lean ldg and 4% cold rich bypass flow.

An updated and extended earthquake catalogue for Greece and adjacent areas since 1900

Abstract. A homogeneous earthquake catalogue for Greece and adjacent areas covering the period 1900–2009 is presented, to be used for reliable seismic hazard studies. The catalogues of Makropoulos and Burton (1981) and Makropoulos et al. (1989), covering the time span 1900–1985, were updated for the period 1986–2009 using instrumentally determined focal coordinates, except for the magnitude from the bulletin of the ISC. For Ms, which is the magnitude scale included in the previous versions, the same procedure applied since 1964 was adopted, using the ISC body wave magnitude (mb) and a regression equation. In the present update, Mw is also calculated for the entire period 1900–2009 using a formula derived from all available moment magnitudes and directly determined by the moment tensor inversion method. Thus, a magnitude homogeneous catalogue concerning both Ms and Mw scales is presented. The extended catalogue contains 7352 events, 70% more than the 4310 events of the previous published (1989) version. The completeness test revealed that the catalogue is complete for magnitudes above 4 for the last 34 yr and that no earthquake with magnitude 6 or greater has been omitted in the whole instrumental era (1900–2009).

A reduced order full plant model for oxyfuel combustion

The linkage of models generated in different commercial and/or proprietary software packages is becoming the state-of-the-art for the investigation of power generation applications. Here, a sophisticated process modelling software package, gPROMS, has been linked with a commercial CFD code, ANSYS FLUENT version 12, in order to create a reduced order model (ROM) for oxyfuel combustion. This is the first such application, and represents a vital step in the evaluation of the impact of oxyfuel operation on a conventional pulverised fuel plant. In order to use existing steam cycle technology, the heat duties to the furnace walls and heat exchangers must match those of conventional combustion. Evidence from experiments conducted by Smart et al. (Fuel 89 (2010) 2468–2476) at 0.5MW scale indicate that this is possible; however there is no operating experience of full-scale technology.A full plant model of a 500MWe sub-critical UK power station has been adapted for oxyfuel combustion. In order to relate heat transfer in the boiler to the level of oxygen enrichment and recycle ratio, a CFD-generated database of results for air and oxyfuel combustion with an excess oxygen value of 5% in both cases has been developed. Non-linear correlations of heat duties for various heat transfer sections of the plant are developed from the database, and linked to the full plant model. The plant model was then investigated over a range of oxygen concentrations from 25% to 35% by volume at the furnace inlet, which corresponds to a dry recycle ratio range of 66–77%. The aim in this case was to assess the potential for fitting oxyfuel burners to an existing plant. The optimum level of oxygen enrichment is found to be 32% and this corresponds to a recycle ratio of 70%. For these conditions the steam temperatures and heat duties closely match those of the conventional air-firing operation.

A parametric modelling study for pressurised steam/O2-blown fluidised-bed gasification of wood with catalytic reforming

A model for pressurised steam/O2-blown fluidised-bed gasification of biomass with catalytic reforming of hydrocarbons and tars was developed using Aspen Plus simulation software. Seven main blocks were used to model the fluidised-bed gasifier and two for the catalytic reformer. Modelling blocks were complemented with FORTRAN subroutines to simulate the observed non-equilibrium behaviour of the process. The model was fitted with experimental data derived from a 0.5 MW scale test rig operated with crushed wood pellets and forest residues and was shown to be capable of predicting product gas composition from gasification of clean wood. A parametric analysis indicated that a significant improvement in the syngas efficiency could be achieved by rising the filtration temperature and reformer conversions. Other improvement possibilities include fuel drying and lower reforming temperature.

Ytterbium doped all-fiber-path all-normal dispersion mode-locked laser based on semiconductor saturable mirror

In this paper, we describe a compact all-fiber-path picosecond pulse based on Ytterbium doped fiber oscillator. A home-made novel SESAM mounted on fiber is reported, by which stable mode locking is obtained. The SESAM possesses the low saturation flux 20 μJ/cm2 (versus prior low saturation flux 32 μJ/cm2), which effectively reduces the pump power threshold of mode locking. The fiber laser generates 15 ps pulse trains without a dispersive delay line or anomalous dispersion in the cavity. Mode locking pulse with 30 MHz basic repetition-rate was produced, with 10–30 mW scale average output power at 1064 nm. Through 60 h of uninterrupted laser operating, mode locking is steady as ever.

SOFC Module Material Development at Fuel Cell Energy

FuelCell Energy (FCE) is engaged in the development of Solid Oxide Fuel Cell (SOFC) power plants under DOE's Solid State Conversion Alliance (SECA) Coal-Based Program. The ultimate goal of the project is to develop Multi-MW SOFC power plants suitable for integration with coal gasifiers and cable of capturing >90% of carbon in coal syngas. FCE is currently utilizing the SOFC stacks developed by Versa Power Systems (VPS) as building blocks for development of the sub-MW and MW scale fuel cell modules. The design of an SOFC stack module is comprised of an assembly of stack blocks to provide targeted dc power. Advanced materials are being developed for gas seals between stacks, mechanical and electrical connections of stack blocks, and thermal as well as electrical insulation within modules. This paper is a review of the progress in development of conducting module gasket (CMG), non-conducting gasket (PH) and electrical contacting paste materials.

Demonstration of pilot scale carbon dioxide capture system using dry regenerable sorbents to the real coal-fired power plant in Korea

Abstract Korea Institute of Energy Research (KIER) and Korea Electric Power Research Institute (KEPRI) have developed the carbon dioxide (CO 2 ) capture system using dry regenerable sorbents since 2002. The principle of the CO 2 capture with regenerable solid sorbents is the reversible reaction between potassium carbonate and potassium bicarbonate in a thermal-swing process. Based on this reaction, we developed a bench scale unit (BSU) which treated 100 Nm 3 /h of flue gas in late 2006. The BSU consisted of a transport fluidized-bed carbonator, cyclones, a loop-seal, and a bubbling fluidized-bed regenerator. We have tested the BSU facility using a slip stream of the real flue gas from a coal-fired circulating fluidized bed combustor located at KIER in order to check the performance of CO 2 removal, the stability of operation. The results showed that more than 80% of CO 2 removal had been maintained during more than 50 hour continuous operation and its maximum reached at the 85% level. Those results indicated that the CO 2 capture system using solid sorbents developed here could be applied to coal-fired power plant. In the meanwhile, we set the small scale unit which consists of two bubbling beds for carbonation and regeneration in order to investigate the effect of several operating variables on the CO 2 removal. The performance of the small scale unit was investigated through the continuous operation with solid circulation under the same experimental conditions as the BSU facility. The CO 2 removal of the small scale unit was reached at the 83% level with the inlet CO 2 concentration of 10 vol.%. The CO 2 removal increased as the water vapor content in the inlet flue gas stream, regeneration temperature, and solid circulation rate increased while it decreased as the gas velocity of the carbonator and carbonation temperature increased. It was found that the performance of the CO 2 removal was very sensitive to the water vapor content in the inlet gas stream and the gas velocity of the carbonator (gas-solid contact time in the carbonator). The construction of 0.5 MW scale pilot plant based on the results of BSU at KIER has been finished in late 2009 at the Hadong Coal-Fired Power Plant, Korea Southern Power Company. The overall performance of pilot plant showed very promising and its CO 2 capture performance reached at the 85% level. A 10 MW scale CO 2 capture plant next development step after 0.5 MWe at the Hadong Coal-Fired Power Plant will be started to construct at the same site in late 2011.

Aerodynamic loads calculation and analysis for large scale wind turbine based on combining BEM modified theory with dynamic stall model

The aerodynamic loads for MW scale horizontal-axis wind turbines are calculated and analyzed in the established coordinate systems which are used to describe the wind turbine. In this paper, the blade element momentum (BEM) theory is employed and some corrections, such as Prandtl and Buhl models, are carried out. Based on the B-L semi-empirical dynamic stall (DS) model, a new modified DS model for NACA63-4xx airfoil is adopted. Then, by combing BEM modified theory with DS model, a set of calculation method of aerodynamic loads for large scale wind turbines is proposed, in which some influence factors such as wind shear, tower, tower and blade vibration are considered. The research results show that the presented dynamic stall model is good enough for engineering purpose; the aerodynamic loads are influenced by many factors such as tower shadow, wind shear, dynamic stall, tower and blade vibration, etc, with different degree; the single blade endures periodical changing loads but the variations of the rotor shaft power caused by the total aerodynamic torque in edgewise direction are very small. The presented study approach of aerodynamic loads calculation and analysis is of the university, and helpful for thorough research of loads reduction on large scale wind turbines.