ASHRAE 4677-2004 Consumptive Water Use for U S Power Production《美国电力生产消费性用水》.pdf
《ASHRAE 4677-2004 Consumptive Water Use for U S Power Production《美国电力生产消费性用水》.pdf》由会员分享,可在线阅读,更多相关《ASHRAE 4677-2004 Consumptive Water Use for U S Power Production《美国电力生产消费性用水》.pdf(5页珍藏版)》请在麦多课文档分享上搜索。
1、1 4677 Consumptive Water Use for U.S. Power Production Paul A. Torcellini, Ph.D., P.E. Member ASHRAE Associate Member ASHRAE Nicholas Long Ronald D. Judkoff Member ASHRAE ABSTRACT Evaporative cooling systems have been criticized for their water use and acclaimed for their low energy consumption, esp
2、ecially when compared to typical cooling systems. In order to determine the overall eflectiveness of cooling systems, both water and energy need to be considered; however, data are needed to compare the amount of energy used at the site to the amount of water used at the power plant. A study of powe
3、r plants and their water consumption was completed to efec- tively analyze evaporative cooling systems. In thermoelectric plants, 0.47 gallons (1.8 L) offiesh water is evaporated per kilowatt-hour Wh) of electricity consumed at the point of end-use. Hydroelectric plants evap- orate an average of 18
4、gallons (68 L) of fresh waterper kWh used by the consumer. The national weighted average is 2.0 gallons (7.6 L) of evaporated water per kWh of electricity consumed at the end-use. From this information, different types of building cooling systems can be comparedfor relative water consumption. INTROD
5、UCTION Eighty-nine percent of electricity production in the U.S. is created by thermoelectric power plants that use thermally driven, water-cooled energy conversion cycles. The evapora- tive or consumptive use is approximately 2.5% of the total water withdrawals or 3,310 million gallons per day (12,
6、530 x 1 O6 Wday). Moreover, hydroelectric plants produce approxi- mately nine percent of the nations electricity. Evaporative water loss from the reservoir surfaces also results in water being evaporated for electrical production. For large HVAC applications, evaporative cooling systems are normally
7、 used in most regions of the U.S. due to their lower capital and operating costs compared to non-evap- orative systems. In addition, direct and indirect evaporative systems are used for directly cooling buildings. However, in hot, dry desert regions, non-evaporative systems are some- times used in o
8、rder to preserve the finite supply of available water. There is a trade-off between water consumption and power consumption used at the site. Direct expansion (DX) systems deceptively consume no water to produce cooling, but they use more electricity than evaporative cooling systems. In many chiller
9、 systems, cooling towers are added to increase the efficiency of heat removal from the condenser, thereby increasing energy efficiency. The water consumption at the power plant and the building must be studied and documented to evaluate the overall water efficiency of different types of building coo
10、ling systems. This paper focuses on water consumption at power plants to provide the data needed to make accurate comparisons between water uses of building cooling systems. This paper does not answer the question of which system consumes more water but merely provides the metric for determining the
11、 amount of water used at the power plant when the amount of energy consumed at the site is known. Subsequent analysis will be completed to determine the water effectiveness of cooling systems. All values reported are for fresh water, which includes lakes, rivers, ponds, and domestic water. A search
12、of water use for thermal and hydroelectric systems was performed. The end result is an aggregated U.S. total of water evaporated by power plants per kWh of energy consumed by the end user (site energy). The analysis accounts for water evaporation at the power plant and is adjusted to incorporate tra
13、nsmission and distribution losses. Hydroelec- tric systems were also evaluated based on evaporative losses Paul Torcellini is a senior engineer, Nicholas Long is a staff engineer, and Ron Judkoff is director at the Center for Buildings and Thermal Systems, National Renewable Energy Laboratory, Golde
14、n, Colo. 96 02004 ASHRAE. from the reservoir per kWh of energy consumed by the end user. The results apply to the location of the production of the electricity, not the location of use. Only aggregated totals are presented because it is currently not possible to “tag” electrons from production to co
15、nsumption, due to the nature of power distribution. The total amount of water evaporated at first seems insignificant compared to the total amount of water passing through the power plant. These values become much more significant when compared to the amount of energy and water consumed in a typical
16、 commercial building or residen- tial home. It is then important to consider the energy-water interface when designing for building cooling systems. WATER CONSUMPTION FROM POWER GENERATION Approximately 89% of the energy produced in the U.S. is generated by thermoelectric systems that evaporate wate
17、r during the cooling of the condenser water (EIA 1999). Hydro- electric plants evaporate water off the surface of the reservoirs and represent approximately 9% of the total power generated in the U.S. Thermoelectric Power Plants In a typical thermoelectric power plant (powered by fossil fuel, nuclea
18、r, or geothermal energy), cooling water removes heat from the cycle with a condenser. Energy from the cooling water is discharged either to a water body or through cooling towers to the atmosphere. The total power plant water with- drawals data used for the analysis described in this paper were foun
19、d through the United States Geological Survey (USGS) (Solley et al. 1998). The USGS calculated the consumptive use of water (amount of water evaporated, transpired, or incorporated into products) for thermoelectric power plants. According to the USGS, these values were calculated by multiplying the
20、water withdrawals by a coefficient of water loss, approximated for each cooling design. If the cooling water was recycled through cooling towers or cooling ponds, the consumptive use was high. Conversely, if the water was used once from a nearby river, then returned to the river, the evaporation at
21、the site was low, but the added heat to the river increased the evaporation rate of the river, thus increasing the overall evaporation. According to the USGS, the total amount of fresh water used at US. thermoelectric power plants in 1995 was 132,000 million gallons (500 x 1 O9 liters) per day (Mgal
22、/day), of which 2.5%, or 3,310 Mgal/day (12.5 x lo9 literdday), was evapo- rated. Mining Water The amount of water that is used for the mining and processing of the fossil fuels that are sent to the power plants also needs to be considered for an accurate analysis. Unfortu- nately, the data availabl
23、e for mining water use are for all types of mining, including coal and ore. This analysis did not attempt to break down the percentages of water that each mining process used. Hydroelectric Power Plants Reservoirs and dams are built for many different reasons, including electric power production, fl
24、ood control, water stor- age, and recreation. Most dams currently provide more than one of the mentioned functions. The discussion of hydroelec- tric dams brings up many difficult issues related to the value of the dam and the values of different individuals. This paper does not make statements or j
- 1.请仔细阅读文档,确保文档完整性,对于不预览、不比对内容而直接下载带来的问题本站不予受理。
- 2.下载的文档,不会出现我们的网址水印。
- 3、该文档所得收入(下载+内容+预览)归上传者、原创作者;如果您是本文档原作者,请点此认领!既往收益都归您。
下载文档到电脑,查找使用更方便
10000 积分 0人已下载
下载 | 加入VIP,交流精品资源 |
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- ASHRAE46772004CONSUMPTIVEWATERUSEFORUSPOWERPRODUCTION 美国 电力 生产 消费 性用水 PDF

链接地址:http://www.mydoc123.com/p-454261.html