Solar Thermal: All Night Long

Bloomberg terminal. But before I moved over to this side of things, I was a BANF analyst. This was back when BEANF really only covered renewables. So in renewables there's wind and solar and now batteries and the other stuff. I looked after the other stuff, mostly geothermal. So geothermal power generation isn't really realistically possible to do everywhere, but think about a place that has volcanoes or hot springs. It probably makes a lot of sense to do it there.

In places it works. It's really a fantastic technology. Okay, So back to the Aha moment. The plan in question was the still Water plant out in the Desert, Nevada in the us look it up. It's owned by the Italian utility in L and they did something really clever. Now and it's a very very basic form. A geothermal power plant works by drawing hot water out of the earth through deep wells I think thousands of feet down. Think oil wells, but instead of oil and gas, they

pull up hot water for brine. This water then flashes to steam to run a turbine, or it heats up another working fluid that vaporizes to run the turbine. What ann L did was they put trough shaped mirrors around the pipes carrying the hot water on its way to the power plant. And what this did with heat up the water even more thereby boosting power output by an extra two megawats from thirty three to thirty five megawats. Not a huge game, but it makes so much sense.

Why wouldn't you do that? Why didn't I think of that? To be honest, maybe I did, and I forgot. I should go back and check my notes. I'm sure I thought it. Yeah, totally. Anyway, this method of using the sun to heat up stuff, well, it's another lesser known renewable solar thermal as we'll hear about in today's episode, it can take a few different shapes and where it's possible,

it's really quite cool. Today we'll talk with BENEF head of solar Analysis, Jenny Chase, about our latest look at this subsector of the solar industry based on the solar thermal market Outlook t BENEF users can get this report on BENEF dot com, the BENEF mobile app, and BENEF go on the Bloomberg terminal. As always, BENEF does not provide investment or strategy advice, and you can hear a

full disclaimer at the end of the show. Him Mark Taylor here with Dana Perkins, and you're listening to Switch on the BENF podcast. Hi Jenny, thanks for joining us today. Hi Danna. We are here today to talk about solar thermal and before we really get into the meat of the research, note, can you explain to us what solar thermal generation is and how it differs from other forms of solar energy like PV. So specifically, we're going to

talk about solar thermal for electricity generation. Now, solar thermal for hate is a whole other field, and that's also quite useful because if you want to take a shower, if you want to feed something into an industrial process heat process. You can use solar thermal to increase the temperature and ben might It takes us much energy to increase to the temperature of water or another fluid from ten to twenty degrees celsius as it does to increase

it from five hundred five and ten degrees celsius. So even using low, relatively low value, low level heat can help. But today we're going to talk about specifically when you concentrate solar thermal into a fluid, make it really hot and run a turbineal boiler and generate electricity from that. Generally, how do you do that? Well, there's two main surviving ways. You can either use a parabolic trough and this is where I wish we had pictures rather than being on

a podcast. You can either look at everyone. So yeah, a powerbolic trough is exactly what it sounds like. It's like, there are these troughs and they concentrate the sun falling on them into a pipe in the middle and they've got that means that they've got miles of piping which contains steam or it's nearly always steam under high pressure

and high temperature. Or you can have a tower design where you have a big field of mirrors and they're all aligned perfectly to focus the heat onto one central boiler. One reminds me of a magnifying glass when I'm a kid, you know, just concentrating the sun down a piece of paper too, well, burn the paper. That's basically what you do. There's also final designs which are using flat mirrors to do the same thing, but they're quite a minority technology,

so well, we'll probably not talk about those. Isn't this generally a minority technology? Yes, Solar thermal electricity generation we got really excited about it in two thousand and eight. We thought, wow, this is cheaper than potable tex, and it was, but that was mainly because le techs was really expensive back then. And then photobole takes got cheap and all we've stopped talking about solo them or so

much so the clast declines didn't come down. But it also has to do with its only useful in very specific locations, and I think you reference very hot locations as being particularly useful for this technology. Why is that, Well, first of all, the cost has come down. I mean we were talking like four hundred and fifty euros and mega hour and two thousand and eight, and we thought

that was cheap. I'm sorry, yeah, it wasn't cheap, but now we thought we thought it was kind of cheap because potobo tex was really expensive, and today some of the lowest bids are coming in around seventy or seventy three dollars and megaw our. I'm a bit skeptical about those, but even our calculations suggests that it's you can do solar them or for a hundred or somewhere between hundred and hundred and fifty degrees dollars for reference pvs AT.

So this is expensive stuff and you can only do it somewhere that has a high amount of direct installation because it doesn't unlike potable tax it doesn't capture reflected or or the fuse slide, so it needs to be really sunny and the sunny needs to beat down directly and not a lot of dust in the atmosphere, which is a problem, and so it's quite specific locations. What it does offer, though, is storage if a couple of things. First of all, it supports the grid better than photoboll

taps because there's a spinning thing. Grids like spinning things. It produces a that produced a c generation actual spinning metal. For everybody listening, it's frequency regulation, right, it's frequency that the proper term is frequency regulations. But basically it's just that you've got inertia if you have spinning metal, and that means that if the grid wobbles, the metal keeps spinning at the same much the same rate, and that

makes the grid wobble less. So you talk about these really hot locations, so we we can't have too much sand. Sand is going to get in the way, but you do need a lot of heat. Where in the world of these projects being built right now, so they're being built a lot of them in Morocco. Part of the reason for that is that the Moroccan government are quite forward looking at about this, and they're thinking about how they're going to decarbonize and supply their country going forward.

A bunch in the United atib emmates and the other thing about the Middle East and North Africa, which fits solar thermal quite well, is that they mostly have a very high peak of energy demand in the evening, and that's where solar thermal's real advantage comes in, because you can actually store energy from solar thermal. You just know something that gets really hot and stays hot, and then you can use it to to make steam to run the turbine after dark. So usually this medium is molten salt.

Salt has a really high specific heat capacity, so it stores a lot of energy when you heat it up. So you make it five degrees centigrade, leave it there, and then when you need the power you use that to make steam and run the turbine. It's a mixture of sodium chlorate and other salts. It's quite a tough fat because this is I'm sure, and it's well insulated as well. You do not want this stuff to freeze.

You especially don't want it to freeze in pipes because that's a right pain in the neck to get out. How many hours of storage are we talking about? Does this get me to the next morning or do I need to go make sure I go to bed before I run out of electricity. You can have as much moden sol as you like. You just make enough of a solar field to heat it up. So Sara Dominado, a plant that's being built in Chile, has seventeen point five hours of storage. It's basically a baseload plant. That's

pretty cool. It's I've always thought of solar thermal, So for everybody listening, I used to I still look at a lot of the geo thermal market, right market, I don't know. And you could argue that geothermal is a lot like solar thermal and that it's kind of like a science project. You get a lot of oh, that's really cool moments, but you also get it peppered with like, okay,

but this is only work in certain specific places. I was used to some of the geo thermal market by the old song nice work if you can get it,

because it works in really specific places. I am going to argue though, that a lot of the conversations we have with analysts talk about the future of electricity and grid connection is a lot of different combinations of things and looking at things that are right for and I get that there's probably certain technologies that have more locations that they could go in, but it is, you know, just an increasingly diverse grid is what potentially we think

the future holds. One of the things you point out in this research note was that solar thermal actually can really benefit from the presence of photovol takes at the same time. So what what is the benefit? Is it economic? It's not exactly that the solar firm will benefits. It's just that photobole tapes is cheaper than solar thermal. So if you average the costs over a bigger plan, you get a lower average cost of energy. But what you can do is solar firm has a lot of parasitic losses.

You've got a pump fluid, you've got to get things started in the morning, you've got to tilt the mirrors, whether they're parabolic, trough or tower and heliostat, and you can actually use photobo tapes to run that since all those things are mainly running when it's light. And then you can use a solar thermal to store your heat in the tank, which means that when the sun goes

down and you can start taking that heat out. So basically, if you hybridize solar thermal with PV, you could provide the daytime power for the grid but also for the parasitic losses, and then you run the solar thermal after dark. Well, technically you take out the stored energy from the solar thermal after dark and you run that turbine and that means you can have baseload power even cheaper than if the whole thing was solar thermal. She met in Morocco,

You met in Chile. Are there other places that are looking at this? Couldn't pop up anywhere else? Well, Spain has done two point three gigawats and stopped. Spain's actually quite marginal for sunniness, quite marginly sunny enough for solar thermal for starters. And secondly, they had this big policy. They built a bunch of fifty megawatch plants that were all mostly kind of the same. They're parabolic trough that that fleet is working quite well, though it took it

a long time to ramp up. But we used to think powabolic trough technology wasn't really improving, but it actually is. It's a good question. But tracking better. I think that it's little things like that because these plants were all built by but their capacity factor actually increased up to so obviously without totally we hoilding these plants, these companies are learning better how to operate them and they haven't been like any big molten salt leaks lately lately. That

a thing, it's a thing. What happens when there's a molten salt leak, you get molten salt everywhere. It's not pretty. No, I mean that sounds like a bummer, But in reality, what does that do to the plant? Is it a big clean up? They have to shut everything down for a really long time. Is it hazardous. It's not that hazards, just salt, but it's hugely disruptive to the plant. You

have to clean it up. I'm pretty sure that there are rules about leaving loads and loads of salts lying around, And of course you have to then get a new containment vessel and another bunch of molten salt, and salt is not super expensive, but it's not cheap either. You have to get a specialized one that meets your property. The mixture is actually quite important, so you want to have a mixture that you understand the properties of, and of course if it leaked out, you probably want to

get a better thing to hold it in. This time, molten salt as a form of storage, I think sort of makes these projects unique because a lot of the time people are talking about lithium ion batteries these days. So my question is, are lithium ion batteries do they have a role to play in the solar thermal space. I think they have a big role in replacing it probably. I think photobotapes and batteries are probably going to ultimately beat so a thermal with molten salt storage to provide

baseload or day long duration power molten salt. At the moment, it is slightly cheaper I think for the long durations over eight hours of storage, but it's not coming down the plants that exist. They run, and actually some of the power trough plants run quite well, but they have they have problems. I think we're probably going to end up using lithium ion more. The other thing with molt salt, interestingly, is that you don't need to use it with solar thermal.

You can just heat it with whatever electricity you've got. I did some back of the envelope calculations for this report about heating it with wind and then using it to provide district heating. Now, the problem with that is that you only cycle it probably once a year or so, and that means that the capex of putting this big molten salt plant underground is quite high if you're only gonna if you're gonna heat it up in summer and

then discharge it in winter. But if you've got wind, a lot of wind in the winter, maybe you can consider something like that. How much would it matter to lose your spinning reserve? This doesn't keep going. I'm not a grid expert, but grid experts don't seem super concerned.

I think that a lot of them are suggesting that if you have batteries that are being that are paid to provide frequency response so that they do respond on a very short time frame to the grid fluctuating, you probably don't need spinning reserve, or not as much as we have. We're spending a lot of time talking about

molten salt rather than solar thermal. But there locations where molten salt is particularly well adept, and not because you do reference putting it with wind or other sources of technology. And I'm just wondering if there are physical barriers. Well, it's a big tank of really hot stuff, so you probably, I mean, you need quite a lot of space, you know,

quite a lot of insulation. You probably don't want to have it right next to somebody's house because if it does leak out, there's going to be a wave of really really hot stuff, and I think you want a bit of a barrier. It is terrifying a volcano. I don't think there's a location big location barrier. You just probably don't want it in your house. Okay, so this is definitely a utility grade solution. And but I mean,

so solar thermal, so we're talking about large projects. Is it hard to find locations for these projects that are actually physically close enough to the consumers that makes it so that the losses are minimal enough so the economic their economically viable projects. I don't think so. I mean, there's a lot of dessert in the world, so in fact, for solar thermal location is not a massive problem. The problem is that no one really wants to pay over

seventy for power. How do they deal with all of the sand and the dirt that does get in the way of the functioning of the plant? They clean them so it's just a out of water. Um, it's usually water.

It can also be done dry cleaning. That dry dry cleaning with with just soft brushes or cloths can actually make more sense in very dusty environments because it's not the sun that so much the problem, it's actually the fine dust that clings to the panels, and particularly in the Middle East, some of that dust if you put water on it, it kind of turns into cement, so you want to dry clean. So this isn't real bad to doing this breshing. This is people mostly at the moment,

it's people, but it could be robots. I think we'll have to have a mirror pressure appreciation day. That sounds like a really intense job. I think it's it's not a great job. You can you can do it at night, of course, so at least, in fact, you prefer to do it at night because so at least you're not necessarily exposed to the desert sun all day. These plants also need to be cooled at certain points, and there's wet cooling and dry cooling. What are the benefits of those.

So basically, whenever you've got a turbine, it's running on heat differentials, so you need to dump the heat somehow. Wet cooling you use water to dump the heat into and some of that evaporates and and a lot of the energy that you're a lot of the temperature that you're trying to lose a lot of the heat heat that you're trying to lose is through evaporation, and that

does use a fair amount of water. Dry cooling is when you just basically expose it to the air and let the air cool it down, which is less effective, but it doesn't use so much water. In a place where it looks like these locations are locations it don't have a lot of spare water to go around. Do you see that is a potential limitation in the high ambient temperature, Yes, it is definitely, definitely a limitation. Yes.

I think nearly all the plants being built at the moment of dry cooling, so they use less than the wet cool plants. How often do you write about solar therpal as a topic, roughly once every two years. It's a quite a slow moving market. There's about six point nine gig of what's installed. We're expecting about eight point six gig of what's to be installed by twenty three, and that's compared with the current photoble type capacity of five hundred gigawatts six handred by the end of this year.

Still a thermal it is rumbling on, and although what we haven't talked about much is tower plants under performing. In fact, the power what trough plants are doing fairly well and becoming quite a mature technology, with plenty of proof that they were so. We will keep an eye on this sector, but in general I am expecting it to lose out to fotial tapes and Pastoriason Jenny, thanks for joining us. Thank you, Mark. Bloomberginny F is a

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