With the overall global ambition to shift from fossil fuel-based energy sources to sustainable ones, such as wind and solar power, the need for energy storage will increase.
In this episode of Science on surfaces - a bigger perspective on the small we talk to Prof. Bengt Kasemo about energy storage and how surface science matters for some of the important storage methods. Prof. Kasemo, who has long experience in surface science and who has worked a lot with sustainable energy and the energy system of the future, explains key concepts and terminology and shares some of his knowledge, thoughts, and ideas on the topic.
As always, we start with the basics and talk about why energy storage is needed and what different ways there are to store energy. We then dig deeper into the storage methods where surface processes are involved, such as batteries and super capacitors, and touch upon the related topic of fuel cells. We also talk about how the surface material properties and surface condition matter, what are the pros and cons of the respective method, including challenges and limitations, and what the future looks like for these methods.
Thanks for listening! If you are interested in surface and interface science and related topics, you should check out our blog - the Surface Science blog
With the overall global ambition to shift from fossil fuel-based energy sources to sustainable ones, such as wind and solar power, the need for energy storage will increase.
In this episode of Science on surfaces - a bigger perspective on the small we talk to Prof. Bengt Kasemo about energy storage and how surface science matters for some of the important storage methods. Prof. Kasemo, who has long experience in surface science and who has worked a lot with sustainable energy and the energy system of the future, explains key concepts and terminology and shares some of his knowledge, thoughts, and ideas on the topic.
As always, we start with the basics and talk about why energy storage is needed and what different ways there are to store energy. We then dig deeper into the storage methods where surface processes are involved, such as batteries and super capacitors, and touch upon the related topic of fuel cells. We also talk about how the surface material properties and surface condition matter, what are the pros and cons of the respective method, including challenges and limitations, and what the future looks like for these methods.
Thanks for listening! If you are interested in surface and interface science and related topics, you should check out our blog - the Surface Science blog
Science on surfaces, a big group perspective on the small
Speaker 2:Welcome to this podcast. Science on surfaces, a bigger perspective on this wall. Here we zoom in on science that impacts our everyday lives. And today we will talk about energy storage and the relevance of surface science for some interview storage methods. My name is Marlene[inaudible] and here with me in the studio, I have professor bank Cosmo. You are professor of physics at childbirth university of technology. Welcome. Thank you. So you have long experience in surface science and you've worked a lot with sustainable energy, the energy systems of the future and energy storage, um, and was your role global ambition to shift from fossil to renewable energy sources? Uh, so for example, wind and solar and the need for energy storage is particularly important. Um, but of course it's important for many other aspects as well. So could you say something or comment on the overall benefits of, and need for, um, energy storage? What are the benefits and drivers
Speaker 1:Generally energy storage enters because the time point when you produce energy and have optimal opportunities to produce energy, doesn't always coincide with when you need energy and therefore you need some kind of intermediate storage. So the energy system generally is built up of production of the entity, maybe transport storage use at the end, and to store energy, there is important for several reasons. One is if you have intermittent energy sources like solar or wind, it blows sometimes sun shine sometimes, but not always, always. And therefore we want to store energy from these sources for later use, for example, for the night. But the story goes that has another function. If you, if you can store energy, you don't need as much maximum power to produce energy for peak peak energy use. If you can store energy and buffer what is produced exactly at that time, you can buffer that we're using also some stored energy. You have a much better situation and you can reduce accurately. The total power that is built. Uh, energy storage is important on essentially all timescale and we fill our gas on the car. It filled it for the travel for the maybe next few hours or for the next day when we store energy for, from summer to winter, it's on several months. And when we store and Indy for long time, for tens of years, decades, we have many, many years as a relevant timescale. And it's interesting to think about our fossil energy resources as stored entity, because it is stored energy that nature stored for us hundreds of millions of years ago. And we harvest that for use on the day scale on the month scale on the maybe decades at most, a few centuries, but still it's a storage of energy that makes our energy supply possible.
Speaker 2:Um, you also mentioned the perspective, I mean, so timescales, but also, um, static versus mobile, I'm thinking you mentioned do we for the cars and stuff. Um, so that is also an aspect in terms of energy storage or usage.
Speaker 1:Yes, that's right. So permanent storage on stationary systems is of course easier. We could take a water dam that can store energy, the water dams of a country like Sweden can store energy for months of use. They are not mobile, uh, but they are big by the car tank or the battery and the electrical vehicle have to be mobile. And there you need to consider volume rate and so on. And also that in these cases, the timescale usually much shorter than than years.
Speaker 2:Um, so you've mentioned a few ways or methods to store energy, water, dams, or oil. Uh, what other methods do we have?
Speaker 1:I could say that we can store energy of different qualities we can store and the electrical energy in batteries. We can store and a D as a chemical entity in fuels. Uh, and we can store energy as heat. Basically. You could say that the quality of the entities falling as you go from an electricity to chemical energy to heat, especially if the heat is low, temperature is usually called low quality by quality. The quality is what it can be used for. So if you have something that is a hundred degrees or 200 degrees hot, you can use it to heat a house, or that you can use that without, uh, elaborate systems to produce electricity while electricity can easily be used to drive electrical engines, but it can also be used for heating. It can be used for anything you want. Another aspect is of course, that to use electrical energy for heating is in a way waste of quality. It's better to use some other lower quality energy too, for heating.
Speaker 2:Mm, okay. Um, so where is the relevance of surfaces here?
Speaker 1:The relevance of substances is that many of those storage systems, especially the chemical storage systems, which are in a way chemical and electrical combined, they use surfaces. And the best examples I can mention for four examples, it's a battery, it's a fuel cell. It's a supercapacitor and it's a catalytic process. So for example, in the battery, both in a battery and in a fuel cell, your store entity as chemical entity in the electrodes, when you have charged the, the battery. So then when you use the battery, you allow chemical reactions to happen at the anode and the catheter, which creates currents in the loop between the anode and the electrode and the electrolyte. So, uh, in the, in the battery, you have chemical and a D and you have electrical entity. The difference between a battery and the fuel cell is that all the entity that is stored in the charged battery is in the electrodes. So you always carry that fuel. If you want with you in a fuel cell, you also have reactions at the electrodes that produce a current, but the react tent, the energy chemical energy comes in from an external source, very, very often hydration, but you can also use other fuels. And when the hydrogen reacts in of the reactions on the anode, then catheter form water, you release energy in the form of electrons that go in the external circuit and create a current. So the difference between a battery and the fuel cell is essentially that the fuel is separated from the BA, from the battery, from the field side. So what, where do we use fuel itself? Fuel cells come, for example, you used, it's not a storage system accurately as a batteries. It's a storage system. Is there in the fuel, in the hydrant. However, very often you think about the fuel cell or something that produce electricity for you with stored energy. So it's the hydrogen that is the storage medium or methanol in Southland. So the hydrogen is a storage and a D, but you need the fuel cells to produce electricity. And you could, for example, produce a hydrogen with electricity. Then you have a loop electricity when you have a surplus produces hydrogen hydrogen in the fuels that produces electricity back when you need it. But it could also be hydrogen that is created by solar energy, by photochemical processes or by electricity from the solar side. Okay. So that's where the fuel cell enters into the storage system as a, as a means of producing electricity from stored any chemical entity. And in what situation would you use a fuel cell, for example, uh, let's go to, uh, a place which is far away from the grid, from the electrical grid. And you produce hydrogen during the day by some photochemical means, or by electrolysis with electricity, from the solar cell. And you produce that hydrogen during the day when the night comes, you have no electricity because you don't have the grid, but then you can use the storage hydrogen to produce electricity from a fuel cell. So in, in this example, the Heidi stored hydrogen and the fuel cell is another alternative to a battery to get night electricity. And what about the super condenser? So per capacitor capacitor supercapacitor is, is a way of, as in a normal capacitor of separating charges in double layers, but you place the geometry such that you have very, very small distances and you get extremely high charge densities, be talking about 10 to a hundred times more energy than in a normal capacitor or, or even thousand times compared to a battery. And the advantage is that they are extremely fast. This means that you can get very high power during a shorter time. So stupid capacity today is it could be seen as a compliment as a competitor to a battery, but I think it's better to see it as a compliment to a battery where you can, depending on, on what the need looks like. If you need fast and the high power super supercapacitor, if you have more low, lower power, a battery, and what is the new high or low power? Well, you can say to, to run the car, uh, at the leisure at normal speeds, it's normal and high is very fast acceleration, but we're talking about moving a car, for example, for example, but it could also be in some, for some, uh, pro chemical processes where you need high peak powers. And when you need high peak powers during your short time, you mentioned a fourth, one was katala CCS[inaudible], and I can take some photocatalysis under the same heading and how surface is center there. We could go back to the traditional catholicy. So oil refining. So oil refining from crude oil produces, uh, products which go all the way from hydrogen, which is not really wanted because there's too much to light hydrocarbons, like me thing, which you also don't want because it's better to use natural gas and so on. So, but you have these fractions of heavier and heavier molecules down to gasoline and diesel and so on. And this, this a refinement in refineries of crude oil to these products was already done by thermal cracking. You let the past towers with different temperatures and you got different products, but when so-called catalytic cracking or cat cracking was introduced, you got much better yield over the molecules you wanted. And these catalysts were called, see your lights. So senior lights have a poor structure that can break very long hydrocarbon molecules, complex ArborCarbon molecules into smaller pieces. And when they do that, you produce higher yields. So the gasoline and diesel, for example, or whatever you want, it's in like a minute, I looked at the poorest poorest on the nanometer scale, or even sub nanometer scale. So that's, uh, one of the role models for catalytic cracking[inaudible] used. So, so that's for breaking apart molecules, but more generally catalysis is used to produce chemicals by entering reactants on the surface of a catalyst. And then you produce some product that you want, where we talked earlier about fuels. That's the reaction that was promoted there, act it also uses a catalyst in the fuel cell or platinum. And what the platinum does is that it combines hydrogen and oxygen to water, which is a lower energy state. And the difference comes out mainly as electricity, but there are many, many reactions where you want catalytic reactions, where you want to go the other way. You want to crack mortar, split water back to the energy recharge area. And again, you can use electricity or electrical potential to help that process, but you can also do it purely thermally. So you have the catalyst, you have water and you provide some heat and the catalyst cracks water to hydrate, and you have your fuel. In some processes, you take help from light, for example, solar light to make a photocatalytic process that has splitting water back to hydrogen, and then you store the high down and use it when you need electricity. Again, for example, in the fuels, and more, generally more generally Qatar catalysis can be used for many different reactions in the energy system. And it's of course, all these examples that are mentioned, batteries, fuel cells, capacitors, and catalysis, our surface basic surface phenomena.
Speaker 2:So you mentioned that the surfaces are involved in all these,
Speaker 1:The example I could add, actually, hydrogen storage. There are several options for hydrogen storage. One is a tank, a gas tank and pressurized, but you can also store hydrogen by letting hydrogen or react with certain metals to form. So called metal hydrates. The typical is magnesium. So you let the hydrogen react with magnesium and the former mag magnesium hydride. And it stores a hydrogen at the density, which is higher than you can issue achieved by guess, storage. It's almost like a solid hydrogen, and then you need, need some energy to release the hydrogen again. But if you're willing to pay that price, you have a very, very convenient storage system.
Speaker 2:So all of these are in use already. They only use already. So what would be a typical situation for each of these, where they are applied or are they all used in similar situations or?
Speaker 1:Um, no. Are they I'd use, uh, I would say in, in different systems, for example, a fuel cell can be used in a house if you want to produce electricity because you are produced in some way, hydrogen. Yeah.
Speaker 2:Or if you're off the grid, as you mentioned, right,
Speaker 1:Right. Uh, in, in the batteries, it's the same, but when you're in mash and battery, you think mainly of cars, but you can also have stationary batteries. So they, they are similar situations. But for example, the, the fatalities is you, I at least think about more large scale production of hydrogen by photocatalysis or by electric metallosis and so on. So then it's more bulky, uh, process that is large industrial scale. And metastasis is a very big process generally in chemical industry. So, so there exists the infrastructure and the knowledge to, to take this general process into the energy system to produce fuels.
Speaker 2:And the supercapacitor where we talked about that
Speaker 1:Super capacity is actually to be honest, more on the development stage stage. So it's not, I wouldn't say that it's used regularly. It's very, in that sense, that is different from battery fuel cells and fatalities is more on the, in the future.
Speaker 2:And then it could be replacing batteries,
Speaker 1:Right, right. Replacing a complimenting
Speaker 2:Placing or complimenting. So what surfaces or surface materials are used in these?
Speaker 1:Uh, several other examples I had, uh, batteries and fuel cells are electrode materials.
Speaker 2:Yeah.
Speaker 1:Yeah. What you want to do is to have, for example, uh, materials that do the battery function or the fuel cell side function, but at the same time, since they already know by system that they are low weight and, and also low volume. So you want to have high power density, but at the same time, they, they are expected to perform the battery function itself. So there may be some conflict conflict between the need for weight while yum versus efficiency. Right. And this is, for example, I think the most well known example is a switch from led battery or led led battery to list him lithium battery and in between the nickel cadmium and so on. So that the switch of material there was very much motivated of course, by the rate led is very heavy and also about key volume buys. So the switch there is motivated by weight and volume, especially weight. And then you run of course, into the problem of, of the, uh, harvesting or lithium as a material, which may be restricted. And therefore, a lot of battery research is devoted to finding new materials, which similar, um, advan advantageous properties has lithium, but more valuable, more accessible like sodium. So for example, I think you could call it almost in the conceptual world, uh, and sodium battery instead of lithium battery would be a great breakthrough without losing performance. It's on the way by, by research. And there are other materials, other ions that you can use now, lithium. So you and so on. So there's a lot of research to circumvent the material problem by going to new materials that are more abandoned.
Speaker 2:Mm. So, so these surfaces, um, how important are the properties in the surface condition?
Speaker 1:They are very important. Of course the surfaces should be durable. They shouldn't be consumed or degraded in Catholicism. For example, one of the standard enemies in catalysis is what is called poisons. So, and the reason that in a fuel cell or in many catalytic systems, I use this platinum or platinum that matters is that it resists poisons. A poison is some chemical that places itself for is that solved on the surface and bind stronger to the surface, then what you want to perform a catalytic action on that. So it's pretty simple. It blocks the access. So sulfur can prevent hydrogen and oxygen from entering the surface and react. And this was for example, in the development of catalytic converters in cars, which are based on novel mattress, like platinum rhodium palladium, this problem that to the P to the prohibition of sulfur containing, uh, fuels. So sulfur was not only an environment or crook. It was also a poison that could poison the catalyst and make it. So by removing more and more the sulfur from the catalyst, you've got a longer life of the catalyst. And in this case, the reactions were not to produce ID and water from hydrogen. It was to convert carbon monoxide to carbon dioxide, and it was also convert nitric oxide and no, and then our tool to reduce them to end two. And both these reactions occur Cara simultaneously on the catalytic converter in a car, in an, in a gasoline car. And, but the action for that requires that the exhausts don't contain any poison, like sulfur, that, that poisons and destroys the catalyst. So it's a very, and that system, that concept can be translated into any new catalytic process that you employ. For example, for, for example, for producing biofuels and, uh, producing, uh, hydrogen from water, which may not be clean enough and so on, you always need to keep an eye on poisoning components in your feet.
Speaker 2:So contamination could be a problem. What about where in the battery, for example, with the electrodes were out,
Speaker 1:They can also wear out because when you, what you do in the batteries that you repeatedly cyclically, you convert the lecturer to a new chemical compound, you oxidize it, you reduce it back and forth and back and forth. And this, so through actions always cause some kind of micro structures changes and these micro sector changes can eventually ruin the battery. So this means that in the design of the electrodes, you may need to put in some stabilizers that are pure, pure, purely for the sake of preventing the degradation of the battery.
Speaker 2:Mm. So if you think about the, the life span of these methods, sort of like how long you can use them for, are they, can they, do they have a limited dive span or
Speaker 1:I think they all have a limited lifespan, but I think the looking back into the history of developing catalytic processes, what you learn for a particular process, if it's sufficiently desired, if it wanted enough, what you learn is to make the catalyst better, to make it more stable, to make it resistant, to poisons, to make it resistant to a structural changes. And if you don't manage on that side, on the electrodes or the catalyst, you also treat the feedstock and say, what is it that destroys my, my catalyst and you remove components of the feedstock. And eventually you build the system with sufficient, longer and longer life. I think for the first catalytic converters in car cars were a question. And really if they could run more than 50,000 kilometers or something like that today, I think the number is 2025, 30,000 kilometers.
Speaker 2:Hm. So certainly improving. Um,
Speaker 1:It's a stepwise successive improving of the whole process.
Speaker 2:So are there any other challenges or limitations in terms of these surface related energy storage methods?
Speaker 1:I think the limitations in the end is, is the economy of, I think you can make a catalytic system that does what you wanted to do, but it may not be affordable. So it's a, it's a competition between many different systems where the economy puts a roof, a ceiling for what you can allow one liter of gasoline to costs. So couldn't make it if you were for, could afford a high price for it, but if it's not affordable, it will not be a technology. Right.
Speaker 2:Of course. So, so then you're thinking about costs for materials that are included, for example, manufacturing
Speaker 1:Or the costs, the manner, for example, purifying the feedstock, if that costs too much. Yeah. The end price will be come too high, or if the catalyst needs to contain too much Novell mattress like platinum, it may be too costly.
Speaker 2:So what about the, um, the energy extraction from these different storage methods? Will you get the same amount of energy out as you entered into the system? Never.
Speaker 1:Yeah. We always lose something. For example, I mentioned the example of hydrogen storage in the metal hydride, since what you basically do when you form magnesium hydride from magnesium and hydrogen gas, you form a chemical compound and it's an exothermic reaction. So you get some heat and usually that heat is wasted. Then you need to supply heat to release hydrogen again. And the overall efficiency depends on how much you lose on these two, the heat that you need to vent away and the heat that you need to supply to get access to the hydrogen, but to make, take another example in, for example, in, uh, in a fuel cell, if you take hydrogen as fuel and you can, for example, run the diesel engine very well on hydrogen as a fuel, but the overall efficiency of the combustion engine is at most 30%, I would say 20 to 30%, but for the fuel cell system, it's something like 70%, even if you accept losing the thermal energy. So there is a big advantage in this number, but you never get a hundred percent back
Speaker 2:As a, just as an example, if you take, you know, these small batteries that you would use in a deck in a torch or something, if you use those rechargeable batteries and you charge it, then what would the loss be?
Speaker 1:I honestly don't know what the efficiency there is. I would say that all energy system have quite large losses, but so for example, the fuel cell example is good. And if you take, if you take nuclear energy, nuclear, energy used for electricity production, the main part of the energy that is produced is going away as thermal energy. You need to use so much water, usually sea water to cool away so much more. There's much more thermal energy produce an electrical energy in terms of,
Speaker 2:Hmm. Okay. Um, there are a few challenges. So where do we currently see the most ongoing research, uh, to push this area forward?
Speaker 1:I think generally the focus today is very much in batteries for electrical storage, especially if you talk about the renewables, renewable energy system. So the battery challenge batteries with higher power density, longer life and so on is probably the main focus. But I think also the other, the chemical systems, if I say so, so to form chemicals by renewable methods, like by solar energy or solar, any food ketalysis or by pure thermal energy coming from the sun, you can build for the reactors that are heated by the solar energy. So there's nothing electrical there, but you get high temperature. And to use that, to produce biofuels into these sustainable renewable energy system is one very important direction. It's, it's a little behind batteries, but I think it will count. Um, we didn't really talk about thermal vanity. You talked about some and I needed something low grade energy, but still the higher, the temperature, the better. And you can do more and more things. So for example, in a, in a bio, in a rare biofuel reactor, where you produce by a fuel, if you can use any different sun to heat the reactor, you have a sustainable energy system to produce biofuels where even the input entity comes from renewables, like the sun. And I think that's an area where there is a lot of research in that area, but it's not on the pro production level yet. Then we have some futuristic, uh, energy storage systems like the year thermal energy year thermal should not be mixed with, uh, what we call, uh, And the divine re-drill a hundred meters or so we talking about thrilling 10,000 meters or more toward talking about kilometers and down there, we have temperatures that can rise to nanny a hundred degrees sufficiently, much to vaporize water to steam, and to use that steam to drive, for example, a turbine.
Speaker 2:Yeah,
Speaker 1:That's an example of a store already stored thermal vanity, but you can also use similar concept, but more Closer to the surface for solar energy, solar energy. If you're not very familiar with solar on it, you usually think about solar cells that produce electricity and electricity that charges a battery or produces hydrogen, but you can also use heat to store energy from night, from day to night. And so if you have big parabolic mirrors that heat water to several hundred degrees C you during the day, you can use this hot steam to melt it souls, which has a high energy of melting. So when it goes from the solid phase to the multi-phase, you store actor, a lot of entity that you can regain during the night by letting the liquid source solidify and sophisticated, but then you buy by that method. You can then produce a steam during the night, and the steam runs a steam turbine in the same way as it does during the day. During the day, the steam is produced directly by the solar radiation. During the night, you are stored entity in this molten salts and the molten salts produce steam for you, but you don't need to switch off the steam.
Speaker 2:No,
Speaker 1:That's an interesting, uh, storage of similar energy. And these are such a solar park and energy parks are or existing in reality, et cetera.
Speaker 2:Okay. So you mentioned there's a lot of focus on batteries. Why is that? Is this a particularly attractive storage? Okay.
Speaker 1:I think it is. I think it's driven very much. We get to something that we surprisingly haven't talked about, the climate issue. So the climate issue is there are many, many different sources for CO2, but I think one could say that the two major, uh, climate crooks are the transport system, the cars, the airplanes, and so on. And it's the electricity production by using coal or natural gas. So that's the bottle of Sierra to as, since one of them is a transport system, you immediately think of Sweeting from gasoline or fuel cars to electrical cars. And I think that's one reason why so much focus is on the batteries that we need to, to meet the demands from the climate challenge. You need another source for driving a car, then the gasoline, then the fossil and the obvious answer is today, the battery.
Speaker 2:So then in this sense, the energy storage method is a limiting factor.
Speaker 1:So limiting factor because you want to store entity. So there are limited two limiting factors. One is the, the primary energy source, of course, solar or wind or so, but the second is also the storage because you can spread out the collection of primary energy over much larger timescale. If you are good batteries,
Speaker 2:I think that's what we had. That's what we had 40 days.
Speaker 1:There is a lot to say about the energy system, but I think if I should say a final word, it is the connection to the climate system is very strong. So when you start looking into the climate challenge, you always end up in one step, you ended up in the energy system and say, the energy system is a major, major source of CO2 or greenhouse gases. There are other sources, diet, food, and so on, but it's really the energy system that is the primary target for solving the client, solving inverted, comma solving, the time challenge
Speaker 2:Mm. And energy storage is
Speaker 1:Instead of storage is part of that. Okay.
Speaker 2:Okay. So that was, uh, interesting to learn more about the relevance of surface science in relation to the energy storage. Um, so that's what we had for today. So thank you for listening to this episode of science on surfaces, a bigger perspective on the small with me, Marlene retro and bank customer, professor of physics at Chalmers university of technology. Thank you. Thank you.