Countries all over the world are working hard to help reduce the amount of carbon dioxide that is released into the atmosphere every day. Not only is this bad for the Earth, but it is also bad for the living things that inhabit the planet. There is also a big concern that the fossil fuels that many countries still rely on will run out and leave cities across the globe without power.
These two problems have been the focus of many new ideas on how to generate energy that is sustainable and better for the environment. Many governments have decided to use wind turbines and solar energy to help reduce their dependency on fossil fuels, and this has led to some groundbreaking projects like the solar tower in Seville, Spain.
In 2001, construction began on the first Concentrated Solar Power (CSP) tower in Europe. Located in Saville, southwest Spain, the PS10 (Planta Solar 10) was the first commercial solar thermoelectric power plant in the world.
The ambitious project used some of the most advanced solar technology available and was the start of an ongoing program of solar plants that Spain plans to build over the coming years.
The tower itself is constructed from concrete and is 115 meters tall. Surrounding the tower, are 624 movable mirrors measuring 120 square meters.
Construction finished on the PS10 in 2005 at a cost of 35 million euros, and one year later, construction began on the next phase of the project PS20.
To generate energy, the plant creates temperatures of up to 250 degrees Celcius at a solar receiver placed at the top of the tower. This energy turns water into steam which then powers a turbine generator to produce electricity. The mirrors called heliostats track and focus the suns energy to the top of the tower and ensure the maximum amount of energy is collected.
At peak capacity, this plant can generate 11MW (Mega Watts) of electricity which is 23 million kWh of electricity per year. This is enough to power 6,000 homes and saves 18,000 tonnes of carbon emissions per year.
As well as generating energy during the day, the PS10 can also store heat as steam. This allows the plant to generate half-load energy for an hour or longer after dark. The water is held in thermally clad tanks and can reach temperatures of up to 255 degrees Celcius. This water is then used to turn the generator after sunset for a short period.
While there are other systems that can store more energy after dark, these use a molten salt technology. The constructors of the PS10 plant wanted to use water as this is less wear on the components and is easier to maintain. However, there is an added benefit to using saltwater to generate the steam. The byproduct of the process is desalinated water which can be a valuable commodity to the hot areas where these power stations are located.
After the success of the PS10, the next phase of the power generation plants was the PS20 which began construction in 2006. This plant uses second-generation technology to enhance the power collection and also make it more efficient.
The PS20 is designed to generate twice the output of the PS10 (20MW). To do this, it has 1,255 heliostats, each with a 120 square meter mirror. The tower is 165 meters tall and generates energy in the same way as the PS10.
With the improved technology and increased capacity, the PS20 can power around 10,000 homes and reduce 12,000 tonnes of carbon dioxide emissions.
Global CSP Plants
In 2018, the total global capacity of CSP plants was 5,500 MW, of this, Spain made up nearly half of this figure with 2,300 MW. The next country was the United States with 1,740 MW.
There are also many other projects that have been completed since Spain began its move towards solar energy. Morocco has a new CSP project since 2019, which is capable of generating 800 MW though it also has 5 hours of thermal energy storage.
Also under construction in 2019 is the DEWA project in Dubai. This uses a combined tower and trough system for a total of 700 MW. It has a huge thermal storage capacity of 15 hours each day.
The trough system uses the same principle of heating the water, but it has the pipes running under each of the mirrors instead of having the mirrors focus on one spot. There are some benefits to the trough system because the mirrors are enclosed in a glasshouse-type structure. It means the mirrors are protected from the elements as well as dust and dirt.
Spain Leading The Way
As well as having the first European solar power tower, Spain is also leading the way with future solar energy projects. They currently have 50 projects approved by the government that is in the works, plus, they also export their technology to other countries. This ensures that Spain will be at the forefront of the solar energy market for many years.
Spain is currently the largest producer of CSP in Europe. This may be because their location on the globe means they benefit from a lot of uninterrupted sun for most of the year. Other countries in Europe tend to favor the wind turbine as a source of renewable energy, however, some of these can’t operate in all types of weather conditions. However, countries like Italy and Germany have started to invest in CSP in the past few years.
With the climate always in the news, it seems likely that more countries in Europe will start to see solar energy power plants as a viable alternative to fossil fuels.