1,227 research outputs found
Potential for Solar Energy in Food Manufacturing, Distribution and Retail
The overall aim of the study was to assess the potential for increasing the use of solar energy in the food sector. For comparative purposes the study also included an assessment of the benefits that could arise from the use of other renewable energy sources, and the potential for more effective use of energy in food retail and distribution. Specific objectives were to: i) establish the current state of the art in relevant available solar technology; ii) identify the barriers for the adoption of solar technology; iii) assess the potential for solar energy capture; iv) appraise the potential of alternative relevant technologies for providing renewable energy; v) assess the benefits from energy saving technologies; vi) compare the alternative strategies for the next 5-10 years and vii) Consider the merits of specific research programmes on solar energy and energy conservation in the food sector.
To obtain the views of the main stakeholders in the relevant food and energy sectors on the opportunities and barriers to the adoption of solar energy and other renewable energy technologies by the food industry, personal interviews and structured questionnaires tailored to the main stakeholders (supermarkets, consultants for supermarket design; energy and equipment suppliers) were used. The main findings from
the questionnaires and interviews are:
- Key personnel in supermarkets and engineers involved in the design of supermarkets are aware of the potential contribution of renewable energy technologies and other energy conservation measures to energy conservation and environmental impact reduction in the food industry. A number of supermarket chains have implemented such technologies at pilot scale to gain operating experience, and more importantly, for marketing reasons, to gain competitive advantage through a green image.
- From installations to date in the UK the most notable are a 600 kW wind turbine at a Sainsbury's distribution centre in East Kilbride and a 60 kWp photovoltaic array at a Tesco store in Swansea.
- The main barrier to the application of renewable energy technologies in the food sector is the capital cost. Even though significant progress has been made towards the improvement of the energy conversion efficiencies of photovoltaic technologies (PVs) and reduction in their cost, payback periods are still far too long, for them to become attractive to the food industry.
- Wind energy can be more attractive than PVs in areas of high wind speed. Apart from relatively high cost, the main barrier to the wide application of wind turbines for local power generation is planning restrictions. This technology is more attractive for application in food distribution centres that are normally located outside build-up areas where planning restrictions can be less severe than in urban areas. In these applications it is likely that preference will be for large wind turbines of more than 1.0 MW power generation capacity as the cost of generation per unit power reduces with the size of the turbine
A Slight Excess of Large Scale Power from Moments of the Peculiar Velocity Field
The peculiar motions of galaxies can be used to infer the distribution of
matter in the Universe. It has recently been shown that measurements of the
peculiar velocity field indicates an anomalously high bulk flow of galaxies in
our local volume. In this paper we find the implications of the high bulk flow
for the power spectrum of density fluctuations. We find that analyzing only the
dipole moment of the velocity field yields an average power spectrum amplitude
which is indeed much higher than the LCDM value. However, by also including
shear and octupole moments of the velocity field, and marginalizing over
possible values for the growth rate, an average power spectrum amplitude which
is consistent with LCDM is recovered. We attempt to infer the shape of the
matter power spectrum from moments of the velocity field, and find a slight
excess of power on scales ~ h-1 Gpc.Comment: 6 pages,6 figures, updated to match accepted versio
The London Heat Island – surface and air temperature measurements in a park and street gorges
This paper reports results from short-term tests carried
out as part of a project to characterize the urban heat island
in London. The investigations looked at air temperatures
upstream and downstream of a park and the surface and air
temperatures within street gorges. It was found that the air in
the park was associated with lower mean (0.6°C [1.1°F] less)
and peak temperatures (1.1°C [2.0°F] less) compared to residential
or shopping streets on either side. The apparent cooling
influence of the park extended downstream between 200 and
400 meters (200 to 400 yards). Measurements in four street
gorges showed a wide variation in surface temperatures—up
to 22°C (40°F)—although 5ºC to 10°C (9ºF to 18°F) was more
typical. For a given façade, lighter surfaces were associated
with lower temperatures, between 6ºC and 10°C (11ºF and
18°F) cooler. A strong relationship was found between mean
gorge surface temperature and the gorge air temperature
measured at 6 m (20 ft) (half-gorge height). This was true for
both a sunny day and a cloudy day. The results suggest that
significant reductions in air temperature may be possible by
adjusting the albedo of urban surfaces
Model for the structure function constant for index of refraction fluctuations in Rayleigh-Benard turbulence
A model for the structure function constant associated with index of
refraction fluctuations in Rayleigh-Benard turbulence is developed. The model
is based upon the following assumptions: (1) the turbulence is homogeneous and
isotropic at or near the mid-plane, (2) the rate of production is in balance
with the rate of dissipation, (3) an inertial region exists, and (4) estimates
for the rate of dissipation of temperature fluctuations and of turbulent
kinetic energy can be made by assuming that the large-scale turbulence is
dissipated in one eddy turnover time. From these assumptions, the dependence of
the structure function on the geometry, heat flux, and the properties of the
fluid is obtained. The model predicts that the normalized structure function
constant is independent of the Rayleigh number. To verify the model, numerical
simulations of Rayleigh-Benard turbulence were performed using two different
approaches: an in-house code based on a pseudo-spectral method, and a finite
volume code which employs a model for the smallest scales of the turbulence.
The model was found to agree with the results of the simulations, thereby
lending support for the assumptions underlying the theory.Comment: 25 pages, 10 figures, 1 tabl
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