We all know about photovoltaic solar panels. But there’s another, almost forgotten type of solar energy: concentrated solar power. Its big advantage is that it can store the sun’s heat for a long time and turn it into electricity when needed – for example at night, when normal solar panels lie idle. Is it set for a comeback?
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Credits:
Reporter: Malte Rohwer-Kahlmann
Video Editor: Frederik Willmann
Supervising Editor: Kiyo Dörrer
Factcheck: Alexander Paquet
Thumbnail: Em Chabridon
Read more:
CSP project databases:
https://solarpaces.nrel.gov/?utm_medium=domain-switch&utm_source=csp&utm_campaign=solarpaces
https://cspdata.com/
NREL best practices study:
https://www.nrel.gov/docs/fy20osti/75763.pdf
Status of CSP plants installed worldwide:
https://www.mdpi.com/2571-8797/6/1/18
Chapters:
00:00 Intro
01:18 How CSP works
02:49 Technology race
05:07 Crescent Dunes
07:03 Comeback?
10:51 Conclusion
Check out this documentary from the late 70s. "…the light is converted directly into electricity. No moving parts. It’s the perfect solar machine." People were fascinated by photovoltaic solar cells. It’s just… they were OUTRAGEOUSLY expensive. "This is the biggest collection of photocells ever assembled. It cost a quarter of a million dollars, yet it only produces enough electricity for three or four families." And that’s where a rival technology came into play: Large mirrors that can also turn sunbeams into electricity. By focusing the light from the sun and using its heat. "What you’re seeing is the world’s first commercial solar electric power plant. It’s called Solar One." Concentrated solar power seemed like the most promising solar technology back then. But skip to today and it’s been almost completely forgotten. The story behind it is one of great expectations… "…pure, clean, consistent and reliable energy…" …equally big disappointment… "…the Crescent Dunes project failed." …and, maybe, one of revival. Because concentrated solar can do one very crucial thing that solar cells can’t. You might have seen a concentrated solar power – or CSP – plant that looks like this before. Especially if you’re into your Hollywood sci-fi. CSP plants can also look a bit less futuristic, like this. But fundamentally, they work the same way: They use mirrors to reflect and concentrate sunlight. "It’s simply grabbing the heat that is coming from the sun. And I really love that." This is Xavier Lara, who calls himself a "CSP evangelist". He’s a mechanical engineer who’s worked on many concentrated solar projects around the world. "So you are concentrating roughly about 1000 times the sun in a particular point." In this type of CSP plant, that particular point would be the top of the tower. Inside it, there’s a fluid – usually molten salt, so salt in its liquid form – that gets heated up by the sun’s energy. The hot molten salt is then pumped down to a generator that boils water to produce steam. Which in turn can be used to spin a turbine that generates electricity. "The same kind that you can have in a normal, let’s say, fossil power plant. But without burning any fossil fuels." After that, the salt has cooled down, so it gets pumped up the tower and the cycle starts again. For this process to work properly, you need a lot of direct sunlight. Which is why you find some plants in countries like Chile, Morocco, the United Arab Emirates or India. But most of them are in the hot parts of Spain and the US. So why is it that when we hear "solar energy", most of us immediately think of photovoltaic solar cells – and not mirrors that concentrate sunlight? "I’m old enough to remember in 2010 or so, we were super optimistic about solar thermal electricity generation." Jenny Chase is a solar analyst at the energy research firm BloombergNEF. Back then, there were, for example, big dreams to set up huge concentrated solar plants in the Sahara and send the electricity to Europe via cable. "For a long time, solar thermal was the main utility-scale solar technology. However, what happened then was that semiconductor technology got really cheap and photovoltaics got super cheap." In a little over a decade, the price for electricity from solar photovoltaics dropped by almost 90%. There were a bunch of reasons for this – mainly policy support in Germany which kickstarted a growing solar industry in China. We covered them in this video, you should check out after this. Concentrated solar power also became cheaper. But in 2011 it started costing more than photovoltaics. Today, it’s more than twice as expensive. This meant people began to turn away from it and put up ever cheaper solar panels instead. "It wasn’t so much that solar thermal lost – it was more that photovoltaics won." That is also because with solar thermal or concentrated solar, every single mirror needs to individually track the sun’s movement, so they always direct the rays to exactly the right point. And depending on the size of the plant, this could be thousands of mirrors. And then you have to account for clouds, which may block one part of the mirror field, but not all of it. That makes it hard to control the temperature at the top of the tower which needs to stay within a fixed range. Compared to all this, solar panels are just pretty easy to handle. "When you then put it on your roof or when you put it on a field or when you put it on a lake or wherever you put it, it’s just very simple." This is Richard Thonig, who’s been researching concentrated solar power technology and policy for the last decade. "It’s just sitting there and you have to clean it maybe from time to time. But it’s not operationally complex as CSP where you have mirrors that you need to adjust under real environmental conditions." CSP plants are generally also custom-built, which makes them expensive. So in order to make them worth it, they need to be BIG, which means more challenging to engineer and handle. A case in point… …this megaproject. "Welcome to the future of power generation!" Crescent Dunes, in the US state of Nevada, was supposed to revolutionize clean electricity. It cost a whopping 1 billion dollars to build and when it started to run in 2015, expectations were high. And then the problems began. It never reached its expected average output, which was supposed to power 75,000 homes. Also because there were lots and lots of outages due to technical problems, often to do with the molten salt the plant used. "Molten salt is a pain to work with because if something does go wrong and it drops below its melting point, then you don’t have molten salt anymore, you have solid salt. And then your pipes are full of solid salt and this is a big pain to sort out." One time, the plant had to shut down for eight months on end. Another time, a molten-salt tank leaked and the ground got contaminated, so the entire tower had to be taken down. The plant eventually closed and SolarReserve, the company behind it, ceased to operate. "They were really rock and roll and Silicon Valley type of guys that were, okay, we’re going to revolutionize the world and we need to build lots of these towers. And they were, you know, move fast and break things. And, and it turns out for CSP, that wasn’t the right approach, right? Because you need to figure stuff out, do operations and maintenance, then build the next plant. It takes some time." Crescent Dunes generates small amounts of electricity again but it tarnished the image of CSP, particularly in the US, which hasn’t built another big plant since. Other megaprojects, like the idea to build big plants in the Sahara to power Europe, also fell flat. Today, ALL of the world’s plants taken together have a generating capacity of 7 gigawatts. For comparison: There are 1,700 gigawatts of photovoltaic solar panels out there. So CSP’s never made it big, and it’s seen its fair share of setbacks. But there is one reason why we shouldn’t give up on the idea yet. And that’s the same reason why China has been building many of these in the past years. Because there’s one thing that photovoltaics can’t do. "The thing about photovoltaics is it really does not generate at night." But concentrated solar can. Newer plants don’t just heat up molten salt to use straight away. They also have big tanks to store it once it’s hot. It only cools by 1 degree Celsius per day in there and can be used to run the turbine at a later point. Like after the sun has gone down. Or when lots of people are using lots of electricity all at once. It’s important to have these clean sources of energy we can dispatch around the clock, as we plug more renewables into our grids. Because they only work when the sun shines or the wind blows. Having this flexible supply might also justify paying a little more. "The future of CSP moved to a different niche, right? So it used to be a power technology like wind and PV, and now it’s really very much a storage technology." There are of course other ways to store electricity, like lithium-ion batteries that now often get built right next to solar farms. But they’re typically used to shift up to four hours’ worth of energy. You can build bigger batteries, to cover the night, for example. But that would be very expensive. Since molten salt is quite cheap, it’s more economical to use this for longer periods. It’s also possible to use electricity from solar panels to heat up the molten salt. But that’s less efficient than directly using CSP to capture the sun’s heat – at least in places with lots of sunshine. "CSP has been in the doldrums for about 15 years because we lost the daytime energy battle. But the reality is for the provision of nighttime dispatchable energy in the deserts, there’s nothing that’s this cheap." This is Craig Wood, the CEO of Vast, a company that’s working on new designs to fix the problems concentrated solar power had in the past. "Without our system, you know, without solar thermal in those hot sunny places, you end up needing to burn fossil fuels for the nighttime energy." They already built this small demonstration plant in eastern Australia to prove their technology works. Their next step is to build a bigger one with eight hours of storage. This report by the US National Renewable Energy Laboratory served as their manual. It was compiled after the failure of Crescent Dunes and analyzes all the problems it and other CSP plants encountered. "And that’s really critical because, you know, if you can’t learn from the mistakes of the past, then there’s not really a future for the technology." As you can see, they built several small towers instead of one big one. They say this makes it easier to build and to vary the size of plants without having to come up with custom designs each time. Which saves money. Also, it’s liquid sodium – so a metal, and not molten-salt – that’s circulating through their system. If this becomes solid in case of a shutdown, it’s easier to melt again than salt. But Vast are not the only ones who took an interest in the CSP report. "That book becomes the Chinese CSP engineer handbook, like their Bible." "What has now changed everything for CSP at the moment is that China is getting into it big." China is rediscovering concentrated solar power. There are around 30 plants in development, way more than anywhere else. That’s because every renewable park with 1 GW capacity now MUST include 10% of storage. And the government issued this notice, saying it will support the "large-scale and industrialized development of solar thermal power". The idea is simple. During the day you use solar PV to produce cheap electricity and concentrated solar to heat up your storage tanks. Then at night, when the solar panels lie idle, you use the stored heat to run your turbine. So what does this mean for concentrated solar? Can the technology really stage a comeback? Well, a lot depends on whether China’s solar towers become a success. "Those solar towers then have a real possibility of developing economies of scale to really figure out how everything works. And then we’ll hopefully see the same thing that we saw with PV or with wind, that those supply chain gains from China really enable very cheap or better products that will be available also in other countries in Africa, potentially in Europe, potentially in the US." But this would also mean those other countries have to see the potential and put policies in place to support the technology. Without support, it will be hard for CSP to get off the ground again. Either way, it will likely never get as big as people once thought it would. Solar cells have won the technology race and captured the mass market. But CSP might have found a new niche. And it will be exciting to see whether it can fill it. "Had you ever heard about this crazy-looking solar technology? And what do you think about it? Let us know in the comments and don’t forget to hit subscribe because we have more videos like this for you every Friday."
45 Comments
What do you think, can CSP really make a comeback?
For one good, means bad, reason is CSPs take a lot of land and not suitable for rooftops. So unlike PV you need a lot of capital (money) and skill for CSPs. In my hood, San Diego, I see roughly 50% of the houses have rooftop PVs.
The capital expense and operations and maintenance costs are significantly more expensive than PV solar. PV solar is being constructed for less than 20 USD cents per mw/hr compared to 50. Then you have the long-term O&M costs which are prohibitive.
Can these mirrors also be made of solar panels? Both reflect and capture energy.
Saw one at a distance before I knew about their existence. They are a really surreal thing to see.
Gallium?
Why we've to use the Salt or Na in the heating tower. Instead, we can use the Water itself in the Heating tower and the Salt should be used in the Storage tanks or nearby water tank. So, we can avoid Solidifying Salt issues in the pipes. Steam should be used turn the turbines and to heat the salt in the tanks at the same time for power storage.
Can be used to heat water and store it to use for space heating and meet daily hot water demands.
The proposal is that cap is better than over because of storage? !! There’s no good reason why PCC can’t utilize molten salt for storage as well
Their sole feature is that they are a battery. Utterly pointless when you can do this with PV.
Those mirrors are called heliostats, but you didn't mention that.
Nuclear is cheaper and works 😂😂
They made one in the desert of Morocco over 10 years ago, and it's been so unprofitable they switched to photovoltaic for the following expansions.
CSP now differs from the past in these ways:-
(1) Modular CSP is more economical than mono CSP (USA)
(2) Sodium heat storage is durable, & China is going to be the 1st country to produce sodium cheaper & cheaper (sodium batteries & CSP investment) in all likelihood
(3) CSP storage is much more efficient than PV battery storage
(4) Will CSP electricity generation require as much water in future?
Can CSP used steam/water be useful for something else?
Very exciting possibilities for the future indeed!
So basically adding a battery?
Seriously don't we have any other way to generate electricity? Than standing on our heads (burn coal, csp, uranium radiation, you name it) just to boil water to turn a turbine? Is there any better way to turn the turbine than heating water? Does the turbine has to turn to generate electricity? We are applying tremendous resources and produce waste to basically create a mechanism to boil water. Because steam engine is the only way? I mean is this civilisation?
No chance for CSP. Photovoltaics is ridiciously cheap. In germany 4cts, in spain and China 1-2ct/kWh. Battery costs are dropping like a stone and are at 4ct/kWh lifetime cost and aiming at 1ct until 2030. AND CSP works ONLY with direct light without clouds. A lot of regions are not suitable for CSP at all.
This tech as at least 10 years old if not more.
Have heard of so many 'game changing' improvements to CSP set-ups, but (with the exception of China.), nothing seems to happen. Weren't more accurate trackers, or machine deformable mirrors, or something supposed to make it profitable again?
why not simply apply real time pricing of electricity, and allow them to export and import electricity? This will encourage everyone to build their own energy storage, and lower their energy consumption during high demand, flattening the demand curve of the day
oooh, love this
Photovoltaics are becoming so cheap, why not just make molten salt batteries? They can take energy from any source.
I am glad that germany changed that law. The in-depth research into photovoltaics to make it more cheap really helped us, especially those of use that live off grid. Photovoltaics is really domestic freedom.
But people should never ever stop researching other technologies like CSP, or other storage technologies (direct or indirect, as you can use photovoltaics too for heating up the salt). Or even fluid batteries.
Never stop. At one point in time it will turn out to be very useful.
9:20 lol that's not how credits work… "google image"
Liquid sodium… that sounds inherently dangerous.
This is great. Thank you 😊
There’s a place in cyberpunk that looks like that
Very good technology
Все дуже просто. Треба генерувати водень, з енергії що не влізла в LiFePO4 батареї. Водень можна зберігати в старих газових резервуарах або виробітках, спалювати та перетворювати в будь яку з потрібних енергій.
It would be interesting to see if you could use solar panels as the mirrors for this concentrated solar power plant.. and another system that I think will be the future system is using water hyacinth farms as the solar collectors and extracting the energy as biomass in a digester system..
Amazing how old failed ideas are being recycled, mainly because the so-called green power revolution has stalled! Nice historical footage of the CSP plants unfortunately now these failed plants are an environmental disgrace! Not just on the land but wildlife that got fried when flying or straying anywhere near it.
Micro inverters are another trend that made a comeback, hitting the market in the mid 2000s and got faded out because of reliability issues but again people are finding out that the roof environment is no place for inverter electronics!
Hydrogen is another failure that is actually power backwards idea.
It takes 55kw to produce 1 kg of hydrogen. This 1 kg of hydrogen can produce 33kw of power!
Now you may think I'm just anti all this stuff but I've been in the industry for 30 years and am very aware of the actual reality and how dire and a juggling circus our power grid has become!
Combine solar Hybrid PV (with heat recovery) and CSP to get more out of the solar energy. This way we can get maximum output and high efficiency and use solar stored energy in night time.
How not get clips and interviews from China as you have from other places.??
Wenn ein Fragezeichen im Titel/Thumbnail ist, ist die Antwort immer Nein.
In my opinion, concentrated solar is the right answer. You missed one of its great advantages – the panels degrade. Every day is less. In 30 years they have to be replaced. Mirrors can be polished, and sodium solidifies and melts for an eternity. In addition they can be receivers for mirrors put in space, so we can have space based energy generation, to send equator bright light anywhere in the world for long hours. After all, what is Musk going to use all those big rockets for? (Hint, it isn't going to be for supporting a vast Mars colony. No money in it.)
I believe that the sunlight could be run through a prism breaking it down into it's frequencies. The visible light could be run through fiber to where it was needed. Any non heat intense frequencies could be used for different functions which are generated now. Heat intense could be separated It would multiply the efficiency.
3:45 – 3:47 Example of unnecessary audio artifacts in S-letters, or maybe AI voice? I've also sometimes noticed DW having overpronounced high end that hurts my ears, maybe the sound guy doesn't have the best hearing?
Misleading thumbnail. It doesnt generate heat at night, it uses the heat it generated in the day.
I prefer pumped storage hydroelectricity, but the more alternatives, the better!
Perhaps it's a hot take but with battery tech improving for consumer devices and EVs, I feel like the night time storage issue is going to be solved at home and not via a centralized solution… Could be wrong though…
People can simply create hydrogen on the day by using excess solar power to be used at night. 😊
Liquid sodium + water = BOOM
I think that the obvious reazon for the making of this video, is that solar panels are short term handy to become later merely garbage, but those concentrated sun power plants are instead an oldened technology that it's been cheaper, and could be attached to those sand batteries from Finland for the storage of heat, while no residuals are produced. So it makes a better business.
Has anyone tried a hybrid plant?
Hype plus useless unrelated 'history' lead up. Not only downvoted, marked as NEVER RECOMMEND CHANNEL.