Energy consumption efficiency measures

Energy consumption is measured in kilowatt-hours per ton of product, the product being either chlorine or caustic. Most operators and technology suppliers choose caustic as the basis for measurement. This choice reflects the practical difficulties of measuring chlorine production accurately and taking into account system losses that end up principally as hypochlorite or HCl. Another comphcation is the dependence of anolyte current efficiency on the amount of acid or alkali present in the feed brine (Section 7.5.6.1). The caustic current efficiency, for all practical purposes, depends only on the membrane efficiency. It becomes more convenient and usually more accurate to measure the production of caustic. One need only measure the amount of solution produced and analyze its caustic content. Again for convenience and accuracy, and assuming the use of membrane cells, it is best to measure the output of cell liquor. This separates the electrolyzer and evaporator test runs. These measurements make it possible to calculate the anode current efficiency from analytical data and hence, to calculate chlorine production and specific power consumption. 

After the average crude oil price increased from 3.18 per barrel in 1970 to 21.59 in 1980, many analysts forecast skyrocketing energy prices for the remainder of the centuiy. The middle price path of the U.S. Energy Information Administration in 1979 projected a nominal price of 117.50 per barrel in 1995 Such forecasts seemed to be soundly based not only in recent experience but also in the economic theoiy of exhaustible resources. As a consequence, U.S. industries invested heavily in energy conseiwa-tion measures, with the result that industrial consumption of energy decreased from 31.5 quads in 1973 to 27.2 in 1985. Some of this investment was probably not warranted on economic efficiency gi ounds because prices ceased to rise after 1981, and even plummeted to 10 per barrel in 1986. 

After 1986, the CAFE and appliance standards in place resulted in stock turnovers to more efficient automobiles and appliances. However, the decline in energy consumption per dollar of GDP slowed appreciably and, between 1986 and 1997, the energy intensity trend remained rather flat. Other forces in the U.S. economy were pushing energy consumption higher, resulting in increases in the energy-intensity measure. 

The potential of mass transit to provide transportation sendees with low energy consumption relies on the high capacity of transit vehicles, since these vehicles have higher energy consumption per vehicle distance traveled compared to private motorized vehicles or nonmotorized modes. Therefore the occupancy rate of transit service is a key factor in determining its energy efficiency. This rate can be measured by the ratio of person distance traveled to vehicle distance traveled. 

Besides the interest in safety, installation, and operational standards for fuel cells, there s also a demand for performance standards measuring energy output, fuel consumption, efficiency, and emissions. 

Catalysis is an important field in both academic and industrial research because it leads to more efficient reactions in terms of energy consumption and waste production. The common feature of these processes is a catalytically active species which forms reactive intermediates by coordination of an organic ligand and thus decreases the activation energy. Formation of the product should occur with regeneration of the catalytically active species. The efficiency of the catalyst can be described by its turnover number, providing a measure of how many catalytic cycles are passed by one molecule of catalyst. 

The efficiency of the overall utility distribution system is an indication of the losses that occur as a result of insufficient thermal insulation, leaking steam traps, etc. When considering an alternative optimization strategy, it is recommended to measure the energy consumption both before and after a particular strategy is implemented so that an accurate cost-benefit analysis can be made and the payback periods of the various strategies can be compared. 

Energy consumption in textile processing is summarized in Table I (20). As a result of conservation measures and more energy-efficient equipment in the U.S. textile industry, average energy consumption per pound of product decreased 12% between 1973 and 1978 (21). 

All heat requirements for the process are provided in the form of open steam at 400 psia. Some is used at the bottom of S-1 to strip HjS and the rest is fed to the twelfth plate in HT-1 to control the temperature of the hot towers and to compensate for heat losses and heat exchanger inefficiencies. Steam consumption is 1778/0.28 = 6400 mol/mol of DjO produced. This is much less than the 200,000 mol/mol DjO needed in water distillation. Additional energy in the amount of 680 kWh/kg D2O is used to circulate gas and pump liquid. This, however, is much less than is used in electrolysis or hydrogen distillation (Table 13.7). The low energy consumption of the GS process is due in large measure to the efficient heat recovery obtainable in the flow sheet Fig. 13.30, which follows Spevack s patent [S7]. 

Energy efficiency indicator An approximation of energy efficiency such as the energy intensity or the specific energy consumption. Most efficiency indicators measure the inverse efficiency if the efficiency increases, the value of the indicator decreases. 

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