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The water in rivers and streams can be captured and turned into hydropower, also called hydroelectric power. The most common form of hydropower uses dams on rivers to create large reservoirs of water. Water released from the reservoirs flows through turbines, causing them to spin. The turbines are connected to generators that produce electricity.
Hydropower is inexpensive, and like many other renewable energy sources, it does not produce greenhouse gas emissions. Some of the oldest hydropower stations in the world were built in the Highlands of Scotland, and are still operating today. In fact, hydropower accounts for about 10% of all electricity used across Scotland.
However, the drawback to hydropower is that damming rivers can change the ecology of the region. For example, the water below the dam is often colder than would normally flow down the river, so fish sometimes die. The water level of the river below the dam can be higher or lower than its natural state, which affects the plants that grow along the riverbanks and sometimes dams silt up.
