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Porsgrunn, Norway

Ulleberg O.,Institute for Energy Technology of Norway | Nakken T.,StatoilHydro Research Center | Ete A.,University of Strathclyde
International Journal of Hydrogen Energy | Year: 2010

An autonomous wind/hydrogen energy demonstration system located at the island of Utsira in Norway was officially launched by Norsk Hydro (now StatoilHydro) and Enercon in July 2004. The main components in the system installed are a wind turbine (600 kW), water electrolyzer (10 Nm3/h), hydrogen gas storage (2400 Nm3, 200 bar), hydrogen engine (55 kW), and a PEM fuel cell (10 kW). The system gives 2-3 days of full energy autonomy for 10 households on the island, and is the first of its kind in the world. A significant amount of operational experience and data has been collected over the past 4 years. The main objective with this study was to evaluate the operation of the Utsira plant using a set of updated hydrogen energy system modeling tools (HYDROGEMS). Operational data (10-min data) was used to calibrate the model parameters and fine-tune the set-up of a system simulation. The hourly operation of the plant was simulated for a representative month (March 2007), using only measured wind speed (m/s) and average power demand (kW) as the input variables, and the results compared well to measured data. The operation for a specific year (2005) was also simulated, and the performance of several alternative system designs was evaluated. A thorough discussion on issues related to the design and operation of wind/hydrogen energy systems is also provided, including specific recommendations for improvements to the Utsira plant. This paper shows how important it is to improve the hydrogen system efficiency in order to achieve a fully (100%) autonomous wind/hydrogen power system. © 2009 Professor T. Nejat Veziroglu. Source


Kane I.A.,University of Leeds | Catterall V.,University of Manchester | McCaffrey W.D.,University of Leeds | Martinsen O.J.,StatoilHydro Research Center
AAPG Bulletin | Year: 2010

Lateral tilting is a common deformation style in extensional basins; its influence on subaerial channels is, to a degree, understood and may be significant, controlling the style of channel development and the resultant sand-body architecture. Growth faulting and lateral tilting in turbidite channel systems have been demonstrated from three-dimensional seismic data, but the resultant architecture of channels within these settings has not yet been documented. In the Carboniferous of northern England, a sand-rich slope channel, developed within a basin undergoing late-stage extension, underwent progressive and unidirectional migration toward a topographic low on a laterally tilting block. The resultant sandstone body is wedge shaped in cross section and composed dominantly of sigmoidal lateral accretion deposits. The channel returned to an axial course before undergoing lateral migration in the same direction, creating a multistory, multilateral channel sandstone body. The repeated unidirectional migration combined with evidence of syndepositional deformation suggests that active tectonism strongly influenced channel evolution and deposition. A model of submarine channel evolution in extensional basins is presented; in systems where large displacements occur, the channel system may avulse, creating isolated sand ribbons, which are connected updip; where the lateral dip is always more influential than the regional dip, the system may pond in the hangingwall syncline. The model is compared to a subsurface channel within the Pliocene of the Nile Delta slope, which was influenced by syndepositional fault movement; application of the outcrop-derived model allows some simple architectural interpretations to be made. Copyright © 2010. The American Association of Petroleum Geologists. All rights reserved. Source


Kumara W.A.S.,Telemark University College | Elseth G.,Telemark University College | Elseth G.,StatoilHydro Research Center | Halvorsen B.M.,Telemark University College | And 3 more authors.
Flow Measurement and Instrumentation | Year: 2010

In this work, a comparison of Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) measurement methods was made applied to oil-water two-phase flow in a horizontal pipe. The experiments were conducted in a 15 m long, 56 mm diameter stainless steel pipe using Exxsol D60 oil (density 790 kg/m3 and viscosity 1.64 mPa s) and water (density 996 kg/m3 and viscosity 1.0 mPa s) as test fluids. The experiments were performed at different mixture velocities and water cuts. Mixture velocity and water cut vary up to 1.06 m/s and 0.75, respectively. The instantaneous local velocities were measured using PIV and LDA, and based on the instantaneous local velocities mean velocities and turbulence profiles are estimated. The measurements are performed in the vertical plane through the pipe center. A double-pulsed Nd:yttrium aluminium garnet (YAG) laser and a high-speed camera with 1260×1024 px resolution (1.3 Mpx) were used for the PIV measurements. The LDA set-up is a two-colour backscatter system with 3 W Argon-Ion Laser. The time averaged cross-sectional distributions of oil and water phases were measured with a traversable gamma densitometer. The measured mean axial velocity and turbulence profiles using PIV were observed to compare favourably well with LDA measurements. Nevertheless, the PIV measurements are more sensitive for optical disturbances in the dispersed region close to the oil-water interface. Hence, this region cannot be confidently analyzed using PIV, whereas LDA offers full-field measurements even at higher mixture velocities. © 2010 Elsevier Ltd. Source


Akselsen O.M.,Norwegian University of Science and Technology | Fostervoll H.,Norwegian University of Science and Technology | Ahlen C.H.,StatoilHydro Research Center
International Journal of Offshore and Polar Engineering | Year: 2010

In the present investigation, hyperbaric welding has been simulated by laboratory welding in a pressure chamber as part of the development programme for fully remote controlled GMA welding. The welding trials of x65 pipeline steel were carried out at pressures of 12, 25 and 35 bar, using one metal cored tubular low-alloy steel and one solid Inconel 625 wire. All welds were characterized by macrographs, hardness measurements, and tensile and impact testing, in addition to metallurgical inspection through light microscopy and microprobe analysis. It is demonstrated that both welding wires can be used to provide high-quality welds under the prevailing conditions, satisfying current requirements set to hyperbaric welding. Copyright © by The International Society of Offshore and Polar Engineers. Source


Strimbeck G.R.,Norwegian University of Science and Technology | Kjellsen T.D.,StatoilHydro Research Center
Forest Ecology and Management | Year: 2010

In experiments with needles of Picea abies, we tested the specific hypothesis that a single night of freezing acts as a signal that triggers a rapid increase in low temperature (LT) tolerance, and the more general hypothesis that repeated or prolonged freezing stimulates increased LT acclimation. In three growth chamber experiments involving acclimation under early- to mid-autumn light and temperature conditions followed by one or more freezing treatments, we found no significant effect of a single night of freezing on LT tolerance, and only limited and inconsistent effects of repeated and prolonged freezing. We also tested the effect of prolonged storage at -5 °C on LT tolerance on samples of three boreal and three temperate conifer species during acclimation under field conditions, and again found no consistent enhancement of LT tolerance attributable to freezing in either group. In agreement with our own and others' anecdotal observations that some species can attain nearly maximal LT tolerance in the absence of freezing under field conditions, we conclude that freezing is neither required nor a major influence in LT acclimation, at least in well-studied boreal conifer species, while the effects of freezing on temperate conifers are not as well-documented. We conclude that freezing treatment of conifer seedlings to ensure sufficient hardiness for late planting seems to offer little practical advantage. © 2010 Elsevier B.V. All rights reserved. Source

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