0:00 About solar thermal energy which is 5…10 times cheaper than coal or natural gas
0:49 How solar thermal energy turns into electricity day and night
1:45 Heat storages on the basis of molten salt, and what is wrong with them
3:20 Concrete heat storages (Concrete instead of the molten salt)
4:49 Heat storages with gravel (or crushed stone)
7:28 Ceramics, stone casting, etc.
8:28 Sand-based heat storages
10:50 Cheaper materials

These mirrors focus solar radiation and convert it into steam, and I am experimentally testing these 5 types of solar heaters and I want to start testing some more new types. My goal is to find the best type which can convert solar radiation into thermal energy at this cost, 0.5 cent / kWh, and it is about 5 times cheaper than the cost of heat from coal, and about 10 times cheaper than heat from natural gas. This cheapness of our solar heat allows a turbine to produce electricity so cheap that it wins competition against thermal and nuclear power plants.

In other words, our solar heaters should be used instead of these mirror structures, which are approximately 10 times more expensive than our cheap heaters. These mirror structures are the basis of more than 100 of solar power plants with a total cost of about $ 40,000,000,000, and now I will quickly remind you how these mirrors turn solar radiation into electricity. When the sun appears, its radiation heats thermal oil inside these tubes to temperatures of almost 400 ºC. This hot oil moves to the center of the solar plant, where a proportion of its thermal energy produces steam for a turbine that generates electricity. The rest of the thermal energy of the oil comes to such heat storages, where the energy heats several tens of thousand tons of molten salt. A few hours later, in the evening or at night, this hot molten salt will produce steam for the same turbine.

Let's turn our attention to similar heat storages, and they are filled with this salt, which is liquid at a temperature of more than 220 ºC. Usually, a heat storage consists of 2 tanks for liquid salt, and this tank stores hot salt, and the 2nd tank holds cold liquid salt. The movement of the liquid salt between the tanks takes place through heat exchangers, where the salt transfers its thermal energy to generate steam for a turbine, or the liquid salt takes thermal energy from the oil which is heated by those solar heaters.

About 100 of these pairs of molten salt tanks have already been built at solar power plants of various types in various countries. But unfortunately, molten salt is very expensive, and this formula tells us that these molten salt storage parameters noticeably increase this cost of our electricity, despite the fact that here we use very cheap thermal energy from our new solar heaters. That is why now my video will describe other types of thermal storages which will allow us to produce very cheap solar electricity, both day and night.

Usually opponents of molten salt tell us about this solar power plant where accidents and shortcomings of this molten salt heat storage were the beginning of a financial disaster for $ 1,000,000,000 investment. So, let's look at other types of heat storages which are dozens of times cheaper and safer than molten salt.

This heat storage consists of a large number of long cylinders of concrete around pipes. It is obvious that if hot thermal oil circulates through those pipes, it transfers its thermal energy to the concrete which, as a result, is heated to high temperatures, up to 400 ºC. We can take this thermal energy from the concrete also through the circulation of thermal oil through the same pipes.

This was an example from a Norwegian company of this name which started building concrete heat storages a few years ago, and recently it received a big investment, but now I am starting to show other examples. This is a German heat storage from a large mass of concrete with a large number of pipes for the circulation of thermal oil.

Now I am showing another example from one of the American companies, and their heat storage consists of concrete parallelepipeds with pipes.

Similar examples may be of interest to us if they correspond to this formula, especially to this total construction cost which should be on the order of several hundred dollars per ton of concrete. We see that a concrete heat storage drastically reduces this cost of our solar electricity by reducing this value compared to the previous formula for heat storages with molten salt, although this efficiency has become worse.