Review of UK microgeneration. Part 1 : policy and behavioural aspects

A critical review of the literature relating to government policy and behavioural aspects relevant to the uptake and application of microgeneration in the UK is presented. Given the current policy context aspiring to zero-carbon new homes by 2016 and a variety of minimum standards and financial policy instruments supporting microgeneration in existing dwellings, it appears that this class of technologies could make a significant contribution to UK energy supply and low-carbon buildings in the future. Indeed, achievement of a reduction in greenhouse gas emissions by 80% (the UK government's 2050 target) for the residential sector may entail substantial deployment of microgeneration. Realisation of the large potential market for microgeneration relies on a variety of inter-related factors such as microeconomics, behavioural aspects, the structure of supporting policy instruments and well-informed technology development. This article explores these issues in terms of current and proposed policy instruments in the UK. Behavioural aspects associated with both initial uptake of the technology and after purchase are also considered

A small-scale seawater reverse-osmosis system with excellent energy efficiency over a wide operating range

A small-scale seawater reverse-osmosis system with excellent energy efficiency is presented. The system promises to deliver up to 460 l/h of potable water, from seawater (at 40,000 ppm), while consuming less than 1600 W of electrical power. This represents a specific energy consumption of less than 3.5 kWh/m3. Moreover, the flow may be controlled in order to reduce the power consumption by a factor of four without any significant loss of efficiency — the specific energy consumption remains near to 3.5 kWh/m3. The keys to these impressive figures are the energy recovery provided by the Clark pump, from Spectra Watermakers Inc., and the use of a variable water recovery ratio control algorithm, developed by CREST. The significance of the system is that it may be operated from variable intermittent renewable-energy sources, such as wind and solar-photovoltaic (PV), without need of batteries. Results of laboratory testing and extensive modeling are presented

Tidal influence on offshore wind fields and resource predictions

The rise and fall of the sea surface due to tides effectively moves an offshore wind turbine hub through the wind shear profile. This effect is quantified using measured data from three offshore UK sites. Statistical evidence of the influence of tide on mean wind speed and turbulence is presented. The implications of this effect for predicting offshore wind resource are outlined

An overview of renewable energy technologies with a view to stand alone power generation and water provision

A brief overview is provided of renewable energy technologies suited to stand alone power generation; in practice this means wind turbines and photovoltaics (PV) as these can be used in diverse locations, and to a lesser extent micro-hydro which is more site specific and bio-energy although this last one may not be effective at the smaller scales mostly involved. The issues concerning the use of wind power and PV for desalination by reverse osmosis will be discussed

Spectral dependence of amorphous silicon photovoltaic device performance

The short circuit currents of a single, double and triple junction amorphous silicon (a-Si) device are investigated for changes with spectral irradiance variation. Two effects have been previously identified; (i) a primary spectral effect that depends purely on the availability of spectrally-useful irradiance within the absorption band of the device, and (ii) a secondary effect that depends also on the spectral distribution within this band. The average photon energy (APE) has been introduced as a useful parameter for describing spectra. It is a device-independent environmental parameter, which effectively puts a figure to the blueness of a spectrum and readily allows the analysis of spectral effects on photovoltaic devices. Single junction cells have a better performance as light becomes more blue-shifted. Double and triple junction cells have a performance that is maximised when the received spectrum is matched to the absorption profile and that decreases when the radiation is either red- or blue-shifted

Effect of operating temperature on the performance of amorphous silicon photovoltaic modules

This paper looks at the effect of operating temperature on the performance of amorphous silicon photovoltaic module

Laboratory demonstration of a photovoltaic-powered seawater reverse-osmosis system without batteries

A prototype photovoltaic-powered reverse-osmosis system has been constructed at CREST, Loughborough, UK. The rate of production of fresh water varies throughout the day according to the available solar power, and thus, the system operates without need of batteries. The system is designed to operate from seawater, and a Clark pump brine-stream energy recovery mechanism is coupled with a variable recovery ratio technique to achieve a specific energy consumption of less than 4 kWh/m3 over a wide range of operation. Measurements showing the variable operation over a two-day period are presented and discussed

The influence of blinds on temperatures and air flows within ventilated double-skin facades

Ventilated façades have become an increasingly employed feature in the design of low energy buildings over recent years in that they offer the attractive features of a conventional glass façade but without the thermal disadvantages. These façades consist of a double skin surface, the outer layer of which is of toughened glass, and the inner layer of which usually comprises conventional double-glazing, behind which is the occupied space. The cavity formed by the outer and inner layers is ventilated, and frequently contains a blind. This blind, together with the cavity ventilation, provides a means to control the heat transfer across the façade, in terms of solar gain transmission and recovery of heat lost from the interior. A three-year project, funded by the UK’s Engineering and Physical Sciences Research Council (EPSRC), has investigated the thermal and airflow performance of ventilated façades. A series of parametric experiments have been performed using the Large Scale Solar Simulator at Loughborough University. Results from these experiments have been used to validate models of airflow and thermal behaviour developed at De Montfort University. Advice on practical application and industrial practice has been provided by Arup Research and Development and IT Power. The result of the research is an improved understanding of the thermal and air flow behaviour of such ventilated double skin façades. The effects of external conditions, solar irradiation and exterior air temperature, on double skin façades with differing internal characteristics are presented and analysed in this paper. In particular, the effect of the blind blade angle on cavity temperatures and ventilation air flows will be reported, together with an outline of the guidance that is now emerging to assist designers of such façades

Tidal, sea-surface roughness and stability effects on the offshore wind power resource

This paper looks at tidal, sea-surface roughness and stability effectson the offshore wind power resourc

A photovoltaic-powered seawater reverse-osmosis system without batteries

An efficient cost-effective batteryless photovoltaic-powered seawater reverse-osmosis desalination system is described. The system has a modest 2.4 kWp photovoltaic array and yet promises to deliver 3 m3/d throughout the year in an example location in Eritrea, operating from borehole seawater (at 40,000 ppm). Existing demonstrations of photovoltaic-powered desalination generally employ lead-acid batteries, which allow the equipment to operate at constant flow. In practice however, batteries are notoriously problematic, especially in hot climates. The system employed here operates at variable flow, enabling it to make efficient use of the naturally varying solar resource, without need of batteries. The system employs standard industrial inverters, motors and pumps, which offer excellent energy and cost efficiency. Maximum power point tracking (MPPT) for the photovoltaic array is provided by a novel and extremely simple control algorithm, developed by CREST. Performance and cost estimates from laboratory testing and extensive modelling are presented