发展大型水力发电系统的前景正受到经济和环境保护考虑的限制。所以,出现的趋势是开发小水电、扩大现有电站的容量和建造大型抽水蓄能电站。据美国联邦能源管理委员会(FERC)估算,美国蕴藏的总水电出力约为17100万千瓦。至1979年1月,不包括抽水蓄能电站,已经开发的水电容量总计约6100万千瓦,约为水电总蕴藏量的百分之35.7。近三十年,水力发电容量的增长已经减慢,已被火电和核电容量的快速增长所超过。因为采用矿物燃料和核燃料的热电站作为基荷电站运行更经济有效,故需要峰荷容量。虽然很多常规水电站正以这种方式运行,但是全部可用的常规水电容量不足以满足峰荷的需 The prospects for developing large hydropower systems are being constrained by economic and environmental considerations. Therefore, the trend is to develop small hydropower, expand the capacity of existing power plants and build large-scale pumped storage power stations. According to estimates by the Federal Energy Regulatory Commission (FERC), the total hydropower output in the United States is about 171 million kilowatts. As of January 1979, excluding pumped-storage power stations, the hydropower capacity that has been developed has totaled about 61 million kilowatts, about 35.7 percent of the total hydropower reserves. Nearly three decades, hydropower capacity growth has slowed down, has been exceeded by the rapid growth of thermal power and nuclear capacity. Because fossil fuels and nuclear fuel plants operate more efficiently and economically as base load substations, peak load capacity is required. Although many conventional hydropower plants are operating in this manner, all available conventional hydropower capacity is not sufficient to meet the peak loads