We anticipated last week that when we talk about solar energy, photovoltaic comes to mind, that is, electric energy generated with panels. But solar energy goes far beyond photovoltaic; there is also great thermal potential that is used to heat spaces, to heat hygienic water and in industrial processes.
It is also possible to generate electric energy with the sun using concentrated solar thermal technology. This operates in a similar way to the other primary sources of electricity; —in fact, it is photovoltaic solar that really uses a different principle—.
How does concentrated solar thermal energy work?
Almost all power plants produce electricity with one principle. This consists of the movement of a turbine connected to an electromagnetic generator that generates electricity. Or, said in another way, it generates electricity that can be used directly or transformed and conducted through transmission networks. This works the same for hydroelectric, wind and thermal plants.
Photovoltaic solar energy works differently. In a very reductionist way, solar panels generate electric current through photons that allow an electron to move between layers of silicon. The important thing, for today, is that in solar panels there is no steam nor turbine nor generator, only a direct current.
In contrast, concentrated solar thermal technology uses the same principle as thermal plants: converting water into steam to move a turbine connected to a generator to produce electricity. For this, thousands of mirrors are used to reflect and concentrate sunlight at the tip of a tower that functions as a heat exchanger using molten salt as a vehicle.
Concentrated solar energy increases the temperature of the molten salt, which is in turn used to generate the water steam that will move the turbine to produce electricity. In the process, the molten salt loses thermal energy and recirculates through the heat exchanger to repeat the process. In this process lies the great difference, strength and weakness, of concentrated solar thermal energy compared with photovoltaic solar energy.
Its strength, compared with photovoltaic energy, is that concentrated solar thermal energy can be stored; since molten salt with high temperature can retain heat between 10 and 16 hours. Consequently, it can be used when there is no solar irradiation, which allows generating continuous electricity without variability and at hours without sunlight.
However, its disadvantage is that it is still a technology with higher development, operation and maintenance costs than photovoltaic solar. Therefore, its progress has not followed the same logic as its photovoltaic sister. So, when you hear about solar energy, remember that there are other ways to use it and achieve decarbonization in the future.
This article was originally published by Business Insider México.
Date: April 27, 2021
Original Link: https://businessinsider.mx/energia-solar-opinion-energia-circular-paul-alejandro-sanchez/ [offline]
Archived Link: https://web.archive.org/web/20220810231024/https://businessinsider.mx/energia-solar-opinion-energia-circular-paul-alejandro-sanchez/ [Archived]