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Concentrated Solar Power

Ivanpah Solar Power Facility in California

Concentrated solar power represents another way of using the power of the Sun to create free and clean electricity and also free and green industrial heat.

Today, we have many solar thermal power stations producing clean energy and heat, but the largest ones are located in the U.S., Spain, Morocco, India, South Africa and the UAE.

Concentrated Solar Power Definition

Concentrated solar power refers to the solar thermal technology that uses mirrors (heliostats) or lenses to concentrate the sunlight into a point located at the top of a tower, to heat an agent (molten salt) and produce steam that will spin a turbine connected to a generator to produce clean electricity.

Another way of producing solar thermal power (parabolic trough) uses a polished metal mirror that is straight in one dimension, and curved as a parabola in the other two dimensions.

The mirror reflects the sunlight in its focal point where we can find a tube filled with a heating agent (mineral oil).

The heated oil will be used to spin the turbine and generate clean electricity, but also as a source of industrial heat.

Concentrated Solar Power versus Photovoltaics

Concentrated solar power (CSP) technology cannot compete with solar PV (photovoltaic) technology in terms of price and operating costs.

Also, CSP technology requires the presence of the Sun (direct sunlight) to work properly, otherwise, in a cloudy weather, the generation capacity is dramatically reduced.

If solar PV technology is mainly used to generate clean electricity, CSP technology has additional uses besides electricity generation.

Researchers are working today to use solar thermal reactors as a source of solar fuels, which can make solar energy a transportable source of power in a not so far future.

We already know that hydrogen is produced today from fossil fuels through a process called steam reforming and through electrolysis.

Steam reforming requires a large amount of heat to extract hydrogen from natural gas, heat that can be provided by CSP technology (the molted salt is heated at high temperatures, reaching peak values exceeding 900°C).

The electricity produced by the solar thermal plant can also be used to separate hydrogen from oxygen in the electrolysis process, which is another way of producing hydrogen from water.

Solar thermal power based on the CSP technology can be used as a source of clean electricity and heat for several industrial processes required to produce clean fuels.

Pros and Cons of Concentrated Solar Power?

The CSP technology relies on a renewable resource (the Sun) to produce clean electricity and heat.

There are several pros of using the CSP technology, but also a few cons.

Pros of Concentrated Solar Power

1. Is a renewable source of energy

CSP technology uses the sunlight to heat the agent (molten salt or mineral oil), which will generate the steam that will rotate the turbine to produce clean energy.

The sunlight is produced by the Sun, which a renewable resource because is here even before the creation of our planet, and will be here to send us free heat and light for another 5 billion years.

2. Is a free and clean source of power

Because the CSP technology relies on the sunlight to produce energy and heat, we can consider this energy resource as a free source of clean electricity because the Sun is sending energy and heat for free.

No fuels are involved in the production of heat and clean electricity when using CSP technology, which means that this technology represents a non-polluting source of power (emission free).

3. CSP technology has low operating costs

Once installed in the field, a solar thermal power plant using the CSP technology will have low operating costs.

Concentrating the sunlight on the tower to heat the agent (molten salt) will lead to reaching high temperatures (around 900°C), which will improve the efficiency, and a higher efficiency means lower costs.

4. Can provide 24/7 electricity production

A solar thermal power plant will be able to heat the agent only if the Sun is up, and there are no clouds to cover the Sun.

If we have a cloudy weather outside, the mirrors used by the power plant cannot use the sunlight to heat the agent.
However, the heated agent (molten salt) can be efficiently and cheaply stored for a later use when the demand for electricity increases.

This way, the power plant can provide clean electricity and heat even during the night or in the cloudy days.

5. Can generate clean electricity at large scale

The largest solar thermal power stations in service today are located in the U.S., Morocco and Spain.
The installed capacity of the top three solar thermal power stations in the world exceeds 300 MW for each power plant.

However, smaller solar thermal power stations are located in many other countries today and they provide clean electricity to a large number of households.

As an example, the Crescent Dunes Solar Energy Project, is a 110 MW solar thermal power plant that uses the CSP technology to heat molten salt and generate steam that spins a large turbine, which then produces clean electricity in the Nevada desert.

At peak hours, the Crescent Dunes Solar Energy Project provides clean electricity for a number of 75,000 homes.

6. Can replace fossil fuels for energy and heat production

The Sun is a renewable resource on our planet and the sunlight that is used by the CSP technology is also a source of alternative energy that is clean and free, which means that it can successfully replace the dirty fossil fuels for electricity and heat generation.

7. Stores energy in a much cheaper way

The solar thermal power plant using the CSP technology produces heat in the first place, and the energy present in the heated agent (molten salt) can be much easily and cheaply stored than storing electricity in batteries.

Cons of Concentrated Solar Power

Relying on a renewable resource such as the sunlight, the CSP technology has also a few drawbacks.

1. Is an intermittent source of power

CSP technology requires the presence of the sunlight to heat the agent that will produce steam to spin the turbine, which means that during the night when the Sun goes down, or during the cloudy days when there is no sunlight available, the power plant will not be able to heat the agent (molten salt).

It is true that the heated agent can be easily and cheaply stored for later use, but if the cloudy weather takes a few weeks, the power plant will have difficulties in producing energy.

2. Represents an expensive technology

For the moment, the CSP technology used by the solar thermal power plants is more expensive than solar PV technology.
This way, building a solar thermal power plant is more expensive than building a solar PV (photovoltaic) power plant.

For example, the Crescent Dunes Solar Project is a solar thermal power plant in Nevada with an installed capacity of 110 MW.

The construction began in 2011, and the cost of the project was $975 million.

Toul-Rosières Solar Park is a solar PV power plant built in France and has an installed capacity of 115 MW.

The construction of the project began in 2011, and the cost was 430 million euros ($559 million using the conversion rates of July 2011).

The investment made in the solar PV station built in France represents only 57.3% of the investment made for the Crescent Dunes Solar Project, which shows how high are the construction costs of a solar thermal power plant compared to a solar PV power plant.

3. Hard to compete against other sources of clean or low-carbon energy

I already showed above that CSP technology is more expensive than solar PV technology.

However, CSP technology is also more expensive than the technology used to turn natural gas into electricity.

Of course that natural gas is a fossil fuel and cannot be compared with the CSP technology that uses a renewable energy resource, but giving the fact that the renewables cannot cover today the world’s demand for energy, we are bound to use low-carbon energy sources such as natural gas in the transition from the dirty fossil fuels like coal and oil to the less polluting sources of power, and finally to the renewables with zero emissions.

4. Concentrated Solar Power is a location dependent technology

Solar thermal power plants that use the CSP technology are usually located in the desert where the Sun shines almost every day.

The problem appears when transporting the electricity produced on long distances because this will involve more investments made to extend the electrical grid.

Also, being located in the desert, the mirrors are often covered by sand, which requires cleaning, and we know that water is not an option in desert areas.

5. Requires a larger area of land

A solar thermal power plant using the CSP technology covers a very large area of land due to the impressive number of large mirrors (mirrors big as a house) involved in the project.

Let’s see another example, to see a real comparison in terms of the land surface covered by a solar thermal power plant and a solar {V (photovoltaic) power plant.

The largest solar thermal power station on the planet today is the Ivanpah Solar Power Facility, which is located in San Bernardino County, California, and has an output of 392 MW (megawatts).

This impressive power plant using the CSP technology covers a land area of 3,500 acres (14.16 km2).

A solar PV power plant with an almost similar output (400 MW) is the Mesquite Solar project built in Arlington, Arizona.

Even if these two solar power stations are producing about the same amount of energy annually, the land area covered by the PV power station is much smaller.

The Mesquite Solar project is built on a land area of only 890 acres (3.6 km2).

Final conclusion

With all these pros and cons, CSP technology (solar thermal technology) is considered a technology of the future that today is still in its infancy.

The costs with the technology are coming down and the cost will continue to come down in the near future mostly due to the breakthroughs in the field.

Article written by:

I write about the renewable energy sector, electric cars and climate change issues. I love nature and good food, so I travel all over the world to see new places and meet new people. Magda Savin

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