Concentrated solar power

Mirrors focus sunlight to make heat that drives a steam turbine, often with molten-salt storage.

Capture · Solar · No. 22

• Capture
• Output: Electricity

Mirror fields heat salt to about 565 C, store it in tanks, and keep making electricity long after sunset.

Chart: Illustration: Concentrated solar power

Where it comes from

Chart: Map of where it comes from

Mirrors focus direct sunlight onto a receiver, heating oil to about 390 C in troughs or salt to about 565 C in towers, which raises steam for a turbine.

Three things to know

1. An estimated 3,500 birds were killed in the first year at the Ivanpah tower plant, burned by concentrated light.
2. Wet-cooled trough plants use a median 906 gallons of water per MWh, more than a coal plant's 687.
3. CSP plants need about 2 hectares of land per megawatt.

The journey

1. 1 Direct sunlightOnly clear desert beams can be focused
2. 2 MirrorsThousands track the Sun across the sky
3. 3 ReceiverMolten salt heated to about 565 C
4. 4 StorageHot salt tanks hold 12-15 hours
5. 5 Steam turbineStored heat raises steam on demand
6. 6 ElectricityServes the evening peak after sunset

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