| 水力发电能源 | hydroelectric energy The free renewable source of energy provided by falling water that drives the turbines. Hydropower is the most important of the regenerable energy sources because of its highest efficiency at the energy conversion. There are two types of hydroelectric power plants: 1. run-of-river power plants for the use of affluent water; 2. storage power plants (power stations with reservoir) where the influx can be regulated with the help of a reservoir. Mostly greater differences in altitudes are being used, like mountain creeks. Power stations with reservoirs are generally marked by barrages with earth fill dam or concrete dams. Though hydropower generally can be called environmentally acceptable, there exist also some problems: 1. change of groundwater level and fill up of the river bed with rubble. 2. Risk of dam breaks. 3. Great demand for land space for the reservoir. 4. Diminution, but partly also increase of value of recreation areas. As the hydropowers of the world are limited,the world energy demand however is rising, finally the share of hydropower will decrease (由流下的水推动涡轮机产生能量。因水力的高能量转换率，故成为最重要的再生能源。有两种型式的水力电厂：a.利用丰沛的河水发电的电厂；b.储存式电厂(水库电厂)，进流水水量可经由水库的调节控制。大部分是利用高度差，如高山溪流。水库电厂通常是有土壤或水泥建造的水坝。虽然水力发电的环境相容性高，但仍有一些问题：1.改变地下水水位，并将河岸填充碎石；b.水坝溃决的危险；c.对土地空间的需求大；d.缩小但也部分增加了休閒地区。世上的水力发电有限，但世上对能源的需求却不断上升，造成水力发电的分配量将会降低。) |
