A project diverts part of a river through turbines and returns the water downstream without creating a large reservoir. What hydroelectric design is it?

A dam stores river water in a reservoir and releases it through turbines when electricity is needed. What design is being described?

A structure across an estuary holds back seawater, and turbines generate as water passes through during changing tide levels. What tidal-power design is this?

Submerged turbines are placed in a fast tidal channel, with no dam across the estuary. What technology is this?

Conventional river hydropower turns turbines with water flowing downhill. What ultimately supplies the energy that puts that water at a high elevation?

How does tidal power differ from river hydropower in what drives the water movement?

A hydroelectric plant's water flow stays the same after a retrofit, but the vertical drop from its reservoir surface to its turbines increases. Which term describes this change?

Which statement correctly compares hydroelectric and tidal electricity generation?

What makes the timing of tidal energy generation predictable?

Which celestial body has the largest influence on Earth's tides?

The Sun also affects tides. What happens when the Sun, Moon, and Earth align near a new or full moon?

During a half moon, the Sun and Moon pull from roughly right angles. What tidal condition results?

A coastal site has a very small difference between high and low tide. Which tidal-power limitation follows most directly?

A tidal-power operator notices that each day's peak generation comes about 50 minutes later than the day before. What explains this shift?

True or false: Tidal power can be predictable in timing while still varying over the tidal cycle.

A tidal-stream turbine is anchored to the seabed in a narrow coastal channel. What feature of its water flow must the design handle that a river turbine's usually does not?

A dam is built across a river used by migratory fish, with no fish passage. What is the most direct effect on the fish population?

A river dam traps sediment that formerly reached a downstream delta. What downstream change is most likely?

What land-use cost occurs when a new hydropower reservoir fills a valley?

A hydropower dam sharply reduces downstream flow during the season when a native fish lays eggs in shallow riffles. Which habitat change is most likely?

A tidal barrage changes how seawater enters and leaves an estuary. Which ecological property is most likely to change?

A tidal barrage reduces the tidal range in an estuary, so less mudflat is exposed at low tide. Which group is most directly harmed?

Marine-energy assessments identify underwater noise, cables, and altered circulation as concerns to monitor. What do these represent?

A site review finds that a small tidal-turbine array has not yet recorded collisions with marine mammals or fish. What conclusion is best supported?

True or false: Renewable electricity projects can still have ecological impacts that require site-specific assessment.

A pumped-storage facility uses surplus electricity to move water from a lower reservoir to a higher reservoir. What is it storing?

When do pumped-storage hydropower facilities commonly pump water uphill?

A utility lets water flow from its upper pumped-storage reservoir down through its turbines. What role is the plant playing on the grid at that moment?

A pumped-storage plant uses 120 MWh of electricity to pump water uphill and later generates 90 MWh. What is its round-trip efficiency?

Why is pumped storage not a net source of energy?