Output characteristics of tidal current power stations

With increasing targets being set for renewable-derived electricity generation, wind power is currently the preferred technology. It is widely accepted that due to the stochastic nature of wind, there is an upper limit to the capacity that can be accommodated within the electricity network before power quality is impeded. This paper demonstrates the potential of tidal energy as a predictable renewable technologies that can be developed for base load power generation and thus minimise the risk of compromising future power quality

Urban wind energy conversion: the potential of ducted turbines

The prospects for urban wind power are discussed. A roof-mounted ducted wind turbine, which uses pressure differentials created by wind flow around a building, is proposed as an alternative to more conventional approaches. Outcomes from tests at model and prototype scale are described, and a simple mathematical model is presented. Predictions from the latter suggest that a ducted turbine can produce very high specific power outputs, going some way to offsetting its directional sensitivity. Further predictions using climate files are made to assess annual energy output and seasonal variations, with a conventional small wind turbine and a photovoltaic panel as comparators. It is concluded that ducted turbines have significant potential for retro-fitting to existing buildings, and have clear advantages where visual impact and safety are matters of concern

Unsteady wake modelling for tidal current turbines

The authors present a numerical model for three-dimensional unsteady wake calculations for tidal turbines. Since wakes are characterised by the shedding of a vortex sheet from the rotor blades, the model is based on the vorticity transport equations. A vortex sheet may be considered a jump contact discontinuity in tangential velocity with, in inviscid hydrodynamic terms, certain kinematic and dynamic conditions across the sheet. The kinematic condition is that the sheet is a stream surface with zero normal fluid velocity; the dynamic condition is that the pressure is equal on either side of the sheet. The dynamic condition is explicitly satisfied at the trailing edge only, via an approximation of the Kutta condition. The shed vorticity is the span-wise derivative of bound circulation, and the trailed vorticity is the time derivative of bound circulation, and is convected downstream from the rotors using a finite-volume solution of vorticity transport equations thus satisfying the kinematic conditions. Owing to an absence in the literature of pressure data for marine turbines, results from the code are presented for the NREL-UAE Phase IV turbine. Axial flow cases show a close match in pressure coefficients at various spanwise stations; however, yawed flow cases demonstrate the shortcomings of a modelling strategy lacking viscosity

Contra-rotating marine current turbines : single point tethered floating system - stabilty and performance

The Energy Systems Research Unit within the Department of Mechanical Engineering at the University of Strathclyde has developed a novel contra-rotating tidal turbine (CoRMaT). A series of tank and sea tests have led to the development and deployment of a small stand-alone next generation tidal turbine. Novel aspects of this turbine include its single point compliant mooring system, direct drive open to sea permanent magnet generator, and two contra-rotating sets of rotor blades. The sea testing of the turbine off the west coast of Scotland in the Sound of Islay is described; the resulting stability of a single-point tethered device and power quality from the direct drive generator is reported and evaluated. It is noted that reasonably good moored turbine stability within a real tidal stream can be achieved with careful design; however even quite small instabilities have an effect on the output electrical power quality. Finally, the power take-off and delivery options for a 250kW production prototype are described and assessed

The implementation of discrete demand management algorithms within energy systems modelling

Traditionally, demand side management (DSM) programs have been driven by utilities. With the prospect of growth in the utilization of building-integrated micro-generation, DSM offers opportunities for additional energy savings and CO2 emission reductions through better utilisation of local renewable energy resources. This paper examines the feasibility of using discreet demand management (DDM) to improve the supply/demand match. For many combinations of micro-generation and DDM controls, it is necessary to know the environmental conditions (i.e. temperatures and lighting levels) within the buildings being modelled. One method would be to embed all the renewable energy technologies and DDM algorithms within a detailed simulation program. An alternative method, investigated in this study, involves coupling two existing tools: a dynamic building simulation program (ESP-r) and a demand/supply matching program (MERIT) that incorporates DDM algorithms and renewable energy system technologies. These two programs interact at the time-step level and exchange calculated parameters (relating to loads, supply potentials and prevailing environmental conditions) to enable an evaluation of DDM techniques in terms of energy saving and occupant impact. This paper describes the technique and presents simulation results relating to a number of building cases

Response to the DECC Consultation of the siting process for a Geological Disposal Facility, 2013

Several members of SEG (Matt Gross, Phil Johnstone, Florian Kern, Gordon MacKerron, and Andy Stirling) have participated in a written response to the Department of Energy and Climate Change’s (DECC) consultation of the siting process for a Geological Disposal Facility (GDF) for nuclear waste. This consultation follows the rejection by Cumbria County Council earlier this year to hosting a Geological Disposal Facility. The government have therefore gone back to the national level to find a suitable location, and the issue remains a multifaceted and controversial one. Matt Gross and Phil Johnstone also represented SEG at the one day consultation on the same issue run by DECC at Centre Hall, Westminster, involving several round-table discussions with civil service, nuclear regulators, and local politicians on the various issues surrounding the siting of a GDF

A global picture of industrial interdependencies between civil and military nuclear infrastructures

Noting the increasingly unfavourable economic and operational position of nuclear power around the world, this paper reviews evidence for a hitherto neglected connection between international commitments to civil and military nuclear infrastructures. Reviewing well established understandings of interlinkages associated with fissile materials and other nuclear weapons related substances, the paper surveys a distinct – and currently potentially more important – kind of interdependency that has up to now received virtually no policy attention. This relates to the national industrial supply chains necessary for the manufacture and operation of nuclear propelled submarines, that are deemed central to strategic military doctrine in a few states – and to burgeoning ambitions in a number of others. One of the most striking features of these interdependencies, is that evidence is so strong in strategic military literatures, but that the issue is typically so neglected in energy policy analysis. So the repercussions extend beyond specific domains of civil and military nuclear policy making in themselves – significant as these may be. Across a range of countries, arguably the most important implications arise for the rigour and transparency of mainstream academic and energy policy analysis and the quality and accountability of wider democratic processes – that are failing to give due attention to the evident force of these connections. With civil nuclear power now increasingly recognised to be growing obsolescent as a low carbon energy source, but key military capabilities evidently depending so strongly on its maintenance, a potentially important new window of opportunity may be opening up for robust measures to reduce global military nuclear threats