The novelty of this invention (from MIT) is a new type of heat storages which are several tens of times cheaper than modern analogues. More detailed description of the invention:    • 100 GWh Crushed Rock Heat Storage for...  

This type of solar power plants can win the competition from thermal power plants, and now the victory of solar energy becomes a reality thanks to the following invention of scientists at the Massachusetts Institute of Technology. I remind you that these mirrors focus solar radiation into this receiver which is a tube for the circulation of liquid thermal oil, and therefore solar energy heats the oil to a temperature of almost 400 ºC.

This hot oil from all receivers forms a large flow in such pipes, and recently the Massachusetts Institute of Technology proposed turning this oil flow into rain. This oil rain must take place in a gigantic trench of this cross section and about a kilometer long. This trench is filled with gravel with a total mass of almost 2,000,000 tons, which is about the same as in such a rock almost 100 meters high.

So, the oil rain starts here. Drops of the hot oil transfer their thermal energy to the gravel and move towards this puddle of colder oil which moves to the receivers for reheating, and so on.

So, this is a heat storage with a large mass of gravel which has a temperature of about 350 ºC, and we can take this thermal energy to generate steam for a turbine with an electric generator. We can take the thermal energy not only during the day, but also at night, and we take the energy through the rain of oil, and its drops are heated by the hot gravel and collect in this oil puddle. This hot oil is taken to generate steam for a turbine, as a result of which the oil loses its thermal energy, and then it becomes the oil rain again, heats up, and so on.

Of course, we know that many of these solar power plants already have such heat storages which are filled with similar molten salt. But these heat storages are several dozen times more expensive than this proposal from the Massachusetts Institute of Technology. In addition, the high cost of these molten salt heat storages means that they only store energy for a few hours of turbine operation in the evening and at night. At the same time, the low cost of our stone heat storage allows us to make it very large, and therefore it can store energy not only for the coming night, but also for non-solar days.

Moreover, we can charge our gigantic heat storages with summer thermal energy, and they will store it until the winter months. That is why our solar power plants can be independent of the weather, and work just as well in non-solar winters as they do in sunny summers. And the quality of our solar electricity will be better than the quality of electricity from thermal power plants which cannot turn their turbines on and off as cheaply and quickly as we can.

Nevertheless, we must win over thermal power plants not only in terms of the quality of electricity, but also in terms of the cost of electricity, and these are the conditions of our victory. This formula requires that we must produce high quality solar electricity at this cost, 5 cent / kWh, and let's analyze whether we can do it.

For example, let's pay attention to this requirement that the thermal energy from our solar heaters must be very cheap, at 0.5 cent / kWh. I remind you that my YouTube channel is trying to find and explore various solar heaters that seem to be able to provide thermal energy at the cost of 0.5 cent / kWh to heat thermal oil with a temperature of several hundred degrees. My videos from this year have already covered at least 4 types of solar heaters we need, and now I am preparing a few more types. My research aims to prove to you that we can find several dozen types that can give us very cheap solar energy which is many times cheaper than heat from natural gas or other traditional energy sources.

Now let's analyze whether this type of heat storage from the Massachusetts Institute of Technology is suitable for our purpose. Unfortunately, this total construction cost of our heat storage looks hard to achieve. In addition, it has large heat losses through this soil and towards groundwater, and these heat losses can significantly degrade this total efficiency.