Concentrated solar power

Big mirrors catch the sun.

They turn light into heat. This heat makes power for us.

How does it work? The mirrors focus the light. This makes a very hot spot. The heat can make steam. The steam then makes power.

Some plants can save the heat. They use hot salt to hold it. This lets them make power at night.

This is a smart way to use the sun. It is a very bright idea!

Concentrated solar power uses mirrors to catch sunlight.

These mirrors focus a large area of light onto one small spot. This makes a very hot area called a receiver.

This heat can be used for many things. It can help cook food or clean salty water. It can also make electricity.

To make electricity, the heat must move. The hot light turns into thermal energy, which is heat power. This heat can drive a heat engine. Some plants use a steam turbine. This is a machine that spins to make power.

One great thing about these plants is storage. Some use molten salt to hold the heat. This is a liquid that stays very hot. Because they store heat, they can make power at night. This makes them very helpful when the sun goes down.

In 2023, the total capacity for this was 8.1 GW. This means there is much more being built today.

Concentrated solar power, or CSP, is a clever way to use the sun.

Instead of just catching light, these systems collect solar heat. This heat can be used for many tasks. It can help cook food or clean salty water. Most importantly, it can make electricity for our homes.

CSP is special because it works differently than other solar tools. It focuses sunlight to create intense heat.

How does this work? It starts with mirrors or lenses. These tools use tracking systems to follow the sun. They focus a large area of sunlight onto one tiny spot. This spot is called a receiver.

The concentrated light turns into solar thermal energy, which is heat. This heat can drive a heat engine. Many plants use a steam turbine to make power. Some systems even use molten salt to hold the heat. This allows the plant to make electricity even at night.

People have been thinking about this for a long time. A legend says Archimedes used a "burning glass" to protect Syracuse.

In 1866, Auguste Mouchout used a parabolic trough for a steam engine. Later, Frank Shuman built a solar station in Egypt in 1913. In 1968, Giovanni Francia built the first concentrated solar plant. It was located in Sant'Ilario, Italy. This plant used a tower design to make 1 MW of power.

There are many different types of CSP plants today. Some use a parabolic trough, which is a long, curved mirror.

Others use a solar power tower with a central receiver.

In 2021, global solar capacity was huge, but CSP was less than 1%. By 2023, CSP reached a total of 8.1 GW. This includes new projects in China and Dubai. The DEWA project in Dubai held a record low price in 2017.

You might know solar panels from your own roof. Those are called photovoltaics, or PV. While PV is very common, CSP is a great partner. This is because CSP can store heat for later use. This makes it "dispatchable," meaning we can use it when we need it. For example, people need more power at sunset.

Just as PV power goes down, CSP can turn its stored heat on.

Concentrated solar power, often called CSP, is a method of capturing solar energy to produce heat.

Unlike standard solar panels that turn light directly into electricity, CSP systems collect solar thermal energy. This heat can be used for various tasks like cooking, desalination, or generating electricity. The process relies on using mirrors or lenses to focus a large area of sunlight onto a much smaller area. This concentrated light is then converted into intense heat. This heat can power a heat engine, such as a steam turbine, or drive a thermochemical reaction.

The mechanism of CSP begins with solar concentrators that use tracking systems. These mirrors or lenses follow the sun's movement across the sky during daylight hours. By concentrating the light, the system creates high temperatures at a specific receiver.

In a parabolic trough system, the light hits a tube filled with a working fluid. This fluid, which might be molten salt, absorbs the heat as it flows through the receiver. The heated fluid is then used as a heat source for a power generation system. This heat typically drives a steam turbine to produce electricity, similar to how fossil fuel stations operate.

There are four main optical types of CSP technology used today. The first is the parabolic trough, which uses long, curved mirrors.

These are classified as linear focus collectors because they focus light along a line. The second type is the concentrating linear Fresnel reflector, which is also a linear focus collector. The third type is the solar power tower, which uses a central receiver.

This is a point focus type because it concentrates light onto a single point. The fourth type is the solar dish, which is also a point focus system. Point focus collectors achieve much higher concentration factors than linear collectors.

The history of concentrating sunlight is filled with both legends and real inventions. A famous legend claims Archimedes used a "burning glass" to repel Roman ships in 213–212 BC.

While historians doubt this story, scientists have tested the idea with mirrors. In 1866, Auguste Mouchout used a parabolic trough to power a solar steam engine. Later, Frank Shuman built a solar thermal energy station in Egypt in 1913. The first modern concentrated solar plant was built by Professor Giovanni Francia in 1968. His plant in Italy used a tower design to produce 1 MW of power with superheated steam.

In the modern era, CSP has seen various stages of growth and technological shifts. The Solar One project in California was a major milestone in the 1980s. It was later converted to Solar Two in 1995, which used a molten salt mixture for storage. This mixture consisted of 60% sodium nitrate and 40% potassium nitrate. While solar photovoltaic (PV) technology grew rapidly due to falling prices, CSP growth has been slower. However, CSP remains highly valuable because it is a dispatchable form of energy. This means it can provide power even when the sun is not shining.

Global capacity numbers show how CSP fits into the wider energy landscape. In 2021, the global installed capacity for all solar was about 1 terawatt. At that time, CSP accounted for less than 1% of that total, standing at only 6.8 GW. By 2023, the total capacity grew to 8.1 GW, including new projects in China and Dubai. The DEWA project in Dubai set a record in 2017 with a price of US$73 per MWh. In the Atacama region of Chile, prices for solar power reached below $50/MWh in 2017 auctions. These numbers show that CSP is becoming more competitive.

CSP is uniquely useful when compared to photovoltaic solar energy. PV systems often struggle with the "duck curve," where power demand peaks at sunset.

This is exactly when PV capacity begins to ramp down. CSP can solve this by using thermal energy storage. It can store heat as sensible heat or latent heat, such as in molten salt. This allows CSP plants to continue supplying electricity during the night. This ability to store energy makes CSP a strong competitor to natural gas and battery-backed PV systems.