Value Of Energy Cost Research Articles

Application of electromembrane technology for providing drinking water for the population of the Aral region

In order to provide drinking water for the population of the Aral region, the electrodialysis (ED) process was selected for desalting well waters containing up to 15 g/L of salts. Two new designs of electrodialysers were developed for adapting the process at the scale of a little village. Experimental tests were conducted in the Aral region. ED has been proved to solve effectively the problem of provision of the Aral region population with drinking water as well as partially demineralised water for irrigation and drinking water for animals. Our cost estimate of drinking water production made from the results of an ED plant exploitation at the Bozoi village in Kazakhstan (capacity is 10 m 3/ h, raw water TDS is 12.9 g/L) gives 1.2 and 0.3 US$ per m 3 when the energy cost is 0.13 and 0.02 US$/kWh, respectively, or 0.1 and 0.025 US$ per kg eliminated salts for the same energy cost values.

Energy costs of standard activities among Indian adults.

To estimate the energy cost of resting (RMR), sitting and standing for urban Indian adults and compare these estimates with the reported values. Energy costs were measured using oxylog while body fat was estimated using equipment (HBF300, OMRON Corporation, Japan) that works on the principle of bioelectrical impedance, for 24 men and 40 women, aged 20-50 y, engaged in sedentary activities. Agharkar Research Institute, Pune, India. Mean energy cost (kJ/min) of resting (RMR), sitting and standing were significantly (P<0.01, for all) higher for men (4.01+/-0.42, 5.0+/-0.72 and 5.74+/-0.69, respectively) than women (3.54+/-0.28, 4.03+/-0.41 and 4.35+/-0.52, respectively). Gender difference increased with the level of activity, from 13% for RMR to 32% for standing. These differences reduced when adjusted (using analysis of covariance) for body weight and became non-significant on adjusting for fat-free mass (FFM) in the case of RMR and sitting activity. The measured values of energy cost (absolute and per kg weight) for these activities were similar to African subjects but lower compared to Asian or European subjects for both sexes. The stepwise regression analysis done separately by sexes showed weight (29%) in men and body mass index (44%) in women to be the best predictors of RMR, while regression analysis for combined sexes indicated FFM and height as predictors of RMR (r(2)=56%, P<0.01). If means to estimate body fat were not available, RMR could best be predicted with BMI and sex as predictors (r(2)=55%; P<0.01). This was mainly due to the fact that the sex differences in our population were more prominent in FFM than that in BMI. Our observations thus indicate the need to develop prediction equations separately for different populations owing to differences in their body compositions, especially in fat mass (FM) or FFM. The energy costs of activities were associated with body composition, especially with absolute fat-free mass, which may vary even with the same body fat percentage. Therefore, there is a need to develop separate prediction equations for different communities.

Energy cost of running in young and adult female athletes

Maximal oxygen uptake (VO2 max.kg-1) and energy cost of running were determined on the treadmill in groups of differently trained young and adult athletes. The VO2 max.kg-1 was in all cases higher in adults than in young athletes. These differences were significant (p < 0.05) in long-distance runners (n = 12, mean age = 24.2 +/- 2.2 vs 17.3 +/- 0.9 yrs, mean VO2 max.kg-1 = 66.9 +/- 4.2 vs 58.2 +/- 4.3 ml.min-1.kg-1), and in middle-distance runners (10, 22.9 +/- 2.8 vs 16, 16.6 +/- 0.8, 62.3 +/- 3.7 vs 56.1 +/- 2.8); in canoeists these differences were non-significant (7, 21.1 +/- 2.1 vs 16.0 +/- 2.3 vs 8, 48.2 +/- 2.6). Values of energy cost of running--coefficients of energy demand of running c, which indicates how much energy is required to transfer 1 kg of body mass on a distance of 1 m--were lower in adult athletes than in young athletes. These differences were significant (p < 0.05) only in long-distance runners (3.69 +/- 0.15 vs 3.84 +/- 0.14 J.kg-1.m-1). In middle-distance runners (3.67 +/- 0.19 vs 3.76 +/- 0.18), and in canoeists (3.84 +/- 0.14 vs 3.86 +/- 0.18) these differences were non-significant. It is concluded that the differences in energy cost of running between trained adult and young female athletes are probably associated with differences in adaptation to the running, and with the technique of movement. Differences in running speed (sports performance) between adult and young athletes are associated with differences in VO2 max.kg-1 and c.

Energy-Efficient Measures and Life Cycle Costing of a Residential Building in Hong Kong

Energy simulations have been carried out for a residential block of flats. Energy-efficient measures such as using tinted and reflective glass, external shading and wall insulation have been studied. Life cycle cost analysis has been applied to these measures to find out the cost effectiveness. Discounting technique has been used to calculate the present value of energy cost over a life cycle of 15 years. This paper presents the findings and discusses the implications.

Effect of protein intake on energy and nitrogen balance and chemical composition of gain in growing boars of high genetic potential

ABSTRACTThe effects of dietary protein (151 to 282 g crude protein per kg dry matter (DM)) and lysine (8·5 to 16·4 g/kg DM) on the carcass composition and energy metabolism of entire male pigs, given food close to appetite, was studied from 33 to 88 kg. Four replicates (three Landrace and one Duroc) of four littermates were used. Energy and nitrogen (N) balances were conducted at approximately 35 to 43, 58 to 65 and 78 to 85 kg and body composition was determined at slaughter. There was no effect of dietary treatment on the crude protein content of the empty body (EBW) but the DM (P &lt; 0·001), fat (P &lt; 0·001) and ash (P &lt; 0·05) proportions and fat: protein ratio in EBW (P &lt; 0·01) increased with decreasing dietary protein level. The mean maximum protein retention was 183 g/day. Retention of protein (P &lt; 0·05) and proportion of protein energy in the gain (P &lt; 0·01) decreased linearly and fat retention (P &lt; 0·001) and energy content of the gain (P &lt; 001) increased with decreasing dietary protein. The N retention values calculated from balance data were proportionately 0·21 higher at high protein intakes (509 g/day) and 0·056 higher at low protein intakes (329 g/day) than the values obtained by slaughter. Using the ideal protein system the value for the efficiency of utilization of apparently digested ideal protein for protein deposition (a2) fell linearly (P &lt; 0·001), based on the slaughter data, as dietary protein content increased. Heat production, calculated from slaughter data, was proportionately 0·07 higher than that measured by indirect calorimetry and 0·17 higher than the computed value for heat production using the standard values of energy costs for maintenance and for protein and fat deposition.

The Assessment of Physical Activity by Leisure-Time Physical Activity Questionnaires

The assessment of physical activity by questionnaire is currently the most popular and practical method of quantifying physical activity levels. Many questionnaires, past and present, have considered overall or habitual physical activity, which includes occupational (or nonleisure) activity. Others have focused specifically on leisure-time physical activity (LTPA) owing to the recognition of its dominating contribution to the total physical activity of developed populations. This review covers questionnaires that wholly or in part attend to LTPA levels. Typically, self-complete or interviewer-administered questionnaires record information on the types, frequency and duration of activities performed over a particular period of time. Activity-specific energy cost values, expressed in metabolic equivalents (METS) or kilocalories, are then commonly used to estimate the total energy expenditure from all activities and/or categories of activities. The validation of LTPA questionnaires has had to rely upon indirect methods, such as the assessment of cardiorespiratory fitness, body composition and activity diaries. The reporting of the reliability of questionnaires has frequently been ignored, although in cases where it has been reported, doubt exists as to whether the consistency of the questionnaire or the consistency of subjects' physical activity habits were being examined. LTPA questionnaires first appeared in the literature in the mid-1960s for use among specific, mainly middle-aged male population groups. Though they varied in their modes of scoring, periods of activity recall, and overall complexity, associations were universally observed between physical activity levels and chronic health conditions. However, it became apparent that different questionnaires did not yield the same results. In 1978, a questionnaire to assess only LTPA, the Minnesota LTPA Questionnaire, was published and despite its substantial limitations, has since established itself as the most popular option available. In recent years, shorter and simpler alternatives have been advocated, though most have yet to be adequately scrutinised. Associations have been found between LTPA and fitness levels, prompting the use of LTPA questionnaires in large-scale fitness surveys of both adults and children. Although LTPA has continued to be estimated in terms of energy expenditure, little attempt has been made to extend existing knowledge on the energy cost of physical activities. Existing values do not accommodate for individual intensities and inter-population activity variations. Consequently, standardised questionnaires are not yet viable. There exists considerable scope for further work with LTPA questionnaires, especially since the association between coronary heart disease and physical activity is now well recognised. Efforts ought to be directed at wider social groups for whom leisure-time activity may have distinct implications.

Desalting water costs using waste heat from power systems combined with the VTFE and vapor compression

An updated desalted water cost comparison will be presented for the Reverse Osmosis, Multistage Flash Evaporator and the high efficiency performance Vapor Compression Vertical Tube Foaming Flow Evaporator (VTFE). The capital cost of the VCVTFE plant is based on a realistic conceptual design for a 2.5 mgd single purpose plant. There are several interesting desalting design concepts that will be presented which can only be realized through the use of the low ΔT vertical tube foaming flow evaporator. Together with the vapor compression cycle, high performance ratios of about 35 lbs. product per 1000 Btus can be readily achieved. These high efficiency concepts and use of waste heat are economical with current day high fuel costs. Conceptual designs will also be discussed of several distillation options using waste heat from a 20 MWe gas turbine. A design of a plant using the waste heat from the bottom end of a power plant for fresh water production from seawater will be presented. Cost comparisons of these low energy consuming concepts will be made with conventional MSF and RO systems. The turbine exhaust steam (waste heat) normally rejected through the seawater cooled condensers can be used to produce distilled water with an efficient vertical tube foaming flow single effect evaporator using enhanced flutted tubes. A discussion will be presented on the VCVTFE process design including the options and selection of the critical hardware for the efficient vapor compression plant design. A summary table will be presented which will include plant capital costs and water costs for several values of energy costs.

The measurement of daily energy expenditure—an evaluation of some techniques

An energy balance survey was conducted on an Antarctic base on 12 individuals for periods varying between 6 and 12 months. Energy expenditure was estimated using two activity/dairy card techniques and mean 24-hr heart rate used in conjunction with a variety of derived heart rate/energy expenditure regression equations. The accuracy of the various techniques was determined by comparison with estimates obtained using energy intakes and changes in body fat. No method of measuring energy expenditure was accurate enough to predict fat gain or loss. Errors in individuals were large and random but the mean error in the estimation of energy expenditure of the community was reasonable. When using the dairy card there was no difference between using measured values for energy costs of specific activities and using values taken from the literature. Using heart rate was no less accurate than the diary card if energy expenditure was predicted from a regression line derived from heart rate and log energy expenditure, and the technique was more acceptable to the subjects.

Energy Cost of Rehabilitation Calisthenics

This study examined the relationship between total energy cost and cardiac effort for a set of graded calisthenics that have been used in cardiac rehabilitation programs. Cardiac effort was quantified by calculating myocardial oxygen cost from the product of heart rate and systolic blood pressure. Total energy cost was determined by measuring oxygen uptake during steady-state exercise. Results indicate that total energy-cost values accurately reflect the cardiac effort required during the performance of these calisthenic exercises by normal subjects.

Energy cost of running and walking in young women

The energy cost of level walking and level and grade running was determined in 7 active women with max VO2 = 50.7 ml/kg-min. Speeds investigated were 4 to 8 km/hr walking and 8 to 14.5 km/hr running. The validity coefficients of several procedures for estimating energy expenditure during locomotion [4 for running (6)(11)(16)(17); 3 for walking (6)(12)(17)] were determined. Correlation coefficients between actual and predicted values were 0.949 to 0.951 with standard errors of estimate 0.79 to 0.80 kcal/kg-hour for walking and 0.856 to 0.975 with standard errors of estimate 0.40 to 0.60 kcal/kg-hour for running. VO2 and kcal energy cost values were similar to those previously reported on men at equivalent walking and running speeds. Efficiency of running based on lift work done was about 25%. Lift work for women was slightly less than values previously reported for men at walking but was slightly more at running. These differences did not appear to have a significant effect on energy expenditure.

Thermodynamic optimum for electrical connections at cryogenic temperatures

This paper compares the energy cost of various electrical connections at cryogenic temperatures. The energy cost is defined as the energy necessary to operate the refrigerator that removes the heat conducted by the connection. If the Wiedemann-Franz law is obeyed, the absolute minimum energy cost per unit of electric current is a function only of end temperatures. The cross sectional area of the conductor and heat removed are determined at each abscissa along the connection. Between room temperature and normal helium boiling temperature (we assume that refrigerators are Carnot refrigerators) energy cost values are: optimum 0·344 W/A, MacFee connection 3·307 W/A, the best connection exchanging heat with helium evaporated at cold end 0·42 W/A, two MacFee connections in series (optimized intermediate temperature) 0·78 W/A.