Scientific innovations for human problems [Energy Supply]. SolarReserve (mirrors + molten salt) (or 75, 000 homes powered with solar energy, 24/7)
Do not consider the posts of the series as a source with comprehensive reviews, but rather as a piece of information you can think about and improve (collaboration) (sometimes you’ll see some unanswered questions in the posts; feel free to share your thoughts/answers).
First of all, I’d like to clarify the meaning of “innovation” in its modern sense.
According to “Oxford Dictionary of English” (3rd Edition, 2010) an innovation is simply
a new method, idea, product, etc.
Wikipedia gives us a similar definition
…"a new idea, creative thoughts, new imaginations in form of device or method". Innovation is often also viewed as the application of better solutions that meet new requirements, unarticulated needs, or existing market needs.
source
So, it’s not about the age. As far as I understand, if an innovation was introduced, let’s say, in 1980, but nothing better has been introduced since that time, it’s still considered as such.
An innovation is something original and more effective and, as a consequence, new, that "breaks into" the market or society
source
SolarReserve
Anyway, let’s talk about SolarReserve now.
During your life you, most likely, noticed that some surfaces reflect the sunlight and you, probably, played with a sunlight spot in the childhood. SolarReserve works based on a similar principle. It is an example of the concentrated solar power (also known as concentrating solar power, concentrated solar thermal, and CSP) system in which solar power tower (aka central tower power plant / heliostat power plant / power tower) technology is used. It consists mostly of a huge amount of mirrors (more than 10,000) and “Receiver” (module partially filled with molten salt) which collects the energy reflected from the mirrors. The latter is placed in the centre of the mirror field on the central tower. The “Receiver” is black (Why?) [17, 18]. Mirrors are oriented automatically towards the target (sun) with the help of solar trackers.
(image source - video below)
There’re two liquids used in SolarReserve, namely water and molten salt.
- Molten salt
Obviously, molten salt is melted salt(s) (also known as Fused Salt(s) (for example, Sodium Nitrite/Nitrate mixture can be used)).
What makes molten salts so special is that it
- can attain high temperature (> 700° C);
- do not expand when freezes as opposed to water;
- has a heat capacity (“The capability of a substance to absorb heat energy” [3]) similar to water (which has the highest heat capacity among liquids),
- can conduct electricity (as opposed to salts in solid state) [2]
Table salt (NaCl) belongs to molten salts (you can check that by heating it to > 801° C (or 1474° F) point when it becomes a liquid) (I wouldn’t recommend to do that, though )).
In case of Solar Power Towers molten salt serves not only as an absorber of the sun energy, but also as a good storage for that energy (because of high heat capacity).
- Water in this case is used to produce steam. The latter is used to drive a traditional steam turbine to generate electricity.
Molten salts “meet” water in a heat exchanger where the steam is generated.
The final process (steam usage) is similar to that happening in systems where coal or gas is used.
The difference is that SolarReserve produces
--> 0% harmful emissions
--> and is 100% renewable
The next animation explains the process in detail
What about solar panels?
Really, why not just place instead of all that stuff a field of solar panels?
One of the problems is that sun energy is available only during a day (well, I know that in polar regions of the Earth days can be very long; they get lower sun energy intensity compared with those on the equator, though (why?)).
Ok, but we could, probably, try to use instead of molten salts just traditional batteries (either 1 super huge one or a huge amount of little ones) to store the sun energy collected with the solar panels.
I think there’s no need to tell you, what environmental impact all those batteries (electronic waste) could have (with all the toxic (for humans and animals at least) materials used in them (lead, cadmium …)).
Also batteries can explode sometimes [4].
Another problem is that solar panels themselves might contain toxic substances.
There’re several types of solar panels. The majority of them (near 90%) consists of glass, aluminium, silver, and an ethylene-vinyl acetate. Other types might contain chromium (human carcinogen and danger for the environment [6]), lead (carcinogen, teratogen [7]), and cadmium [5].
As for Cadmium, just take a look at those 4 red rhombuses at the top of the page on PubChem to realise how dangerous it is [8].
Solar panels usually can last for 25-30 years because solar cells lose their efficiency. And the waste they become represents a big problem to us and our environment [9].
In November 2016, the Environment Ministry of Japan warned that the country will produce 800,000 tons of solar waste by 2040, and it can’t yet handle those volumes
source
Most parts of the solar panels can be recycled
including up to 95% of certain semiconductor materials or the glass as well as large amounts of ferrous and non-ferrous metals
source
Nonetheless, if the glass breaks (due to rain, hail, hurricanes, accidents), those toxic substances can leak into the soil -> water system (which is bad news for us).
Puerto Rico’s second largest solar farm, located in Humacao, took a direct hit from Maria’s eyewall. The farm currently accounts for nearly 40% of solar-produced electricity on the island and is currently under expansion to produce even more. Unfortunately, a majority of the newly added solar panels were ripped from their foundation and completely destroyed by Maria’s strong winds.
source
What’s more is that the solar cells manufacturing process itself is energy-consuming and quite dangerous for the environment (CO2…).
Wires used in solar panels might contain silver, copper and some other elements [5].
Problems with CSP systems
There’re some problems with CSP systems as well.
1\ Location
Obviously, SolarReserve requires intensive sunlight. You can find a lot of it in the regions near equator.
But in other regions of the world (like Great Britain) it makes less sense to install SolarReserve-like solution due to lack of the sunlight.
(The image was taken from Wikipedia. It’s under Attribution 4.0 International (CC BY 4.0) license. No changes were made)
So, we need somehow to transfer all that energy generated with CSPs to highly-populated regions like Europe.
In fact, there’s an electric power transmission system called high-voltage, direct current (HVDC) power transmission (aka power superhighway / electrical superhighway) system, which might allow to transfer the electric power efficiently between continents [10].
2/ Costs
Mirrors are made of glass coated with silver (or aluminium (there’re other options as well)) [11].
Well, I didn’t find any reliable information of how much silver is used per square metre of glass (I‘ve found some, but some books which I can’t afford).
SolarReserve system has more than 1 million of square metres of glass. Thus, you can imagine how mush kilograms (or even tons) of silver SolarReserve needs.
Also SolarReserve (and other CSPs) requires a lot of pipes and tanks, which are made of metals (mostly copper and aluminium, I suppose).
You know, I was going to dig deeper and make a comprehensive research about the prices of different sources of energy to figure out what the cheapest source is.
But I believe …
No matter how much SolarReserve-like solutions costs, it worth it.
Billions?
According to some information on Wiki the largest CSP (in which solar power tower technology is used and which has near 173,500 heliostats (mirrors)) costs near $2 billion [12].
They want to know what the figures are, how much it will cost to do that.
That's a price system question.
Do we have resources to do it?
That's the real question.
Jacque Fresco - Language in Transition, Research, Animal Testing, Energy Comparison - Oct. 25, 2011
So, do we have enough silver/aluminium on the Earth to make all those mirrors?
Can we provide enough salts for the “Receiver”?
Do we want to continue to pollute the Earth by using traditional sources of energy (and even by using some alternative sources)?
Or do we want a source of renewable energy with 0% harmful emissions?
America's wealth is not its gold, is not its banking institutions.
These are false institutions.
And the entire money-structured and materialistic-oriented society is a false society.
Jacque Fresco on "Larry King" Live Full (1974)
3/ Desert conditions
It shouldn’t be a surprise that the mirrors in the desert wouldn’t be clean.
They become quickly covered with dirt and dust. And how much water would you need to clean all those more than 1 million of square metres of mirrors?
The good news is that there’s so-called self-cleaning glass/mirrors.
The bad news is that the component used to turn general mirrors into self-cleaning mirrors is titanium dioxide [13].
And …
Evidence for Carcinogenicity
Cancer in humans: There is inadequate evidence in humans for the carcinogenicity of titanium dioxide. Cancer in experimental animals: There is sufficient evidence in experimental animals for the carcinogenicity of titanium dioxide. Overall evaluation: Titanium dioxide is possibly carcinogenic to humans (Group 2B).
source
I hope they’ll find other solutions to keep those mirrors clean.
4/ Environmental impact
I don’t know exactly, but I suppose that just like with the solar panels the manufacturing process of the parts needed for CSP itself might be dangerous for the environment (again, CO2 emissions…).
Or do they use alternative sources to produce that?
Also some CSP systems like Ivanpah
they are burning small amounts of natural gas in order to produce steam to jump-start the solar generating process. They say burning natural gas always has been part of the process.
source
So, at least in some cases there’re no 0% harmful emissions.
Anyway, as for CO2 emissions, the overall impact should be positive for environment. For example,
The Ivanpah installation was estimated, before operations started, to reduce carbon dioxide emissions by more than 400,000 tons annually.
source
What impact CSP systems have on wildlife?
At least CSP systems might affect birds, insects and desert tortoises.
Insects might be attracted by the light -> birds might be attracted by the insects (their food).
Birds might collide with the mirrors or be burned in radiant flux (from the mirrors) [14].
According to some reports
"biologists working for the state estimated that 3,500 birds died at Ivanpah in the span of a year, many of them burned alive while flying through a part of the solar installment where air temperatures can reach 1,000 degrees Fahrenheit [540 °C]"
source
It continues to operate as though there's an endless supply of birds to burn
Garry George, project director for Audubon California
SolarReserve team solved the problem by rearranging the mirrors (as far as I understand).
Focus no more than 4 mirrors on any one place in the air during standby.
We have had zero bird fatalities since we implemented this solution in January, despite being in the standby position as well as flux on the receiver for most days since then,” he said. “This change appears to have fully corrected the problem.”
source
To install a system like SolarReserve, a lot of people are needed. So, projects like SolarReserve might help us to reduce unemployment.
As I mentioned earlier, SolarReserve is just 1 example of CSP in which solar power tower technology is used. For more examples go to https://en.wikipedia.org/wiki/List_of_solar_thermal_power_stations
What do you think about CSP systems?
Feel free to share your thoughts.
The Truth is Born in Argument
[presumably Socrates]
Any ideas on how to improve the systems?
References
https://pubchem.ncbi.nlm.nih.gov/compound/5352425#section=Health-Hazard
“Erik Pihl: Concentrating Solar Thermal Power - Pros and Cons” video on YouTube
(was used as the basic source for the “Problems with CSP systems” section)https://www.solarreserve.com/en/
(SolarReserve. Official site)"SolarReserve - The Future is Here" video on YouTube
"SolarReserve - Concentrated Solar Power Technology Animation" video on YouTube
Other posts of this series
Scientific innovations for human problems. Introduction
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