Renewable energies in Spain are gradually gaining ground in the market, especially thanks to the measures allowed by the Government. Among them, solar thermal energy has shown great progress, contributing to covering almost 4% of all electricity demand in Spain during the summer. This figure has been published by Protermosolar, the association representing the Spanish solar thermal energy sector. In June, solar thermal energy generation reached 4,4% of total demand, reaching a record on June 19 when 9,4% of the country's total demand was covered. 
Facilities in Spain
Currently, in Spain there are 50 operational solar thermal power plants with an installed capacity of 2.300 megawatts (MW), placing us in first place worldwide in terms of installed capacity. These solar thermal power plants have been crucial for the generation of renewable electricity, contributing 4,4% in June, 4% in July and August, and 3,1% in September, figures comparable to photovoltaic production. Although photovoltaic power has twice the installed capacity, solar thermal compensates with its energy storage capacity. Most of the solar thermal plants in Spain are managed by leading companies such as Abengoa, Elecnor or the Cobra Group. In addition, Protermosolar highlights that the plants with thermal storage systems have been essential to guarantee supply during the night, generating more than 700 MW from sunset until around 5 in the morning. 
How solar thermal energy works
Solar thermal energy requires the concentration of solar rays in a fluid that is heated to generate steam. This steam in turn moves a turbine connected to a generator that produces electricity, allowing energy to be injected into the electrical grid. Unlike photovoltaic energy, which directly transforms sunlight into electricity, solar thermal energy requires this intermediate step, which also allows it to store energy through thermal salt systems. These storage systems reflect an advantage of solar thermal energy over other renewable energies, as they can continue generating electricity at night or during cloudy times.
Types of solar thermal plants
There are several types of solar thermal plants depending on the technology used:
- Parabolic troughs: They use parabolic cylindrical mirrors that concentrate the sun's rays on a heat-transfer fluid. This process is the most common in Spain.
- Heliostats with receiver in central tower: This technology uses moving flat mirrors that reflect the rays towards a central receiver located on a tower.
- Fresnel linear reflectors: It uses flat mirrors instead of parabolic ones, which reduces costs and improves the accessibility of the technology.
- Stirling parabolic dishes: Each disk concentrates sunlight on a Stirling engine coupled to a generator, allowing for modular production of electricity.
These technologies are constantly evolving and their efficiency is expected to improve in the coming years thanks to research, especially at the Almería Solar Platform, one of the most advanced centres in Europe.
Solar thermal energy storage
One of the strongest points of solar thermal plants is their storage capacity through thermal salt tanks. This allows electricity to be generated even at night, as mentioned above, which gives it a comparative advantage over other renewable sources, such as photovoltaics, which do not have this intrinsic capacity. Plants with thermal storage can release their energy according to demand, which makes solar thermal a valid option to cover energy peaks during the night.
Increasing the efficiency of solar thermal plants
According to studies by Protermosolar, solar thermal plants are improving their efficiency year after year. This increase is mainly due to the learning curves obtained since the first Spanish plants began to operate. In 2015, the aggregate production of solar thermal plants was exceeded for the first time. 5 terawatt hours (TWh).
Furthermore, the development and implementation of hybrid technologies that combine solar thermal energy with photovoltaic energy has improved the economic viability of new installations and projects, allowing for continuous electricity production by combining both technologies.
Spain, thanks to its geographical conditions and its commitment to renewable energy, remains the world leader in solar thermal energy. With proper planning and investment, Spain has the potential to maintain its position and continue to increase the installed capacity of this technology in the coming years.