Today I'm excited to launch Episode 1 of the Heat Pump Review podcast . In the first episode, I'll be talking to James Ma , who - at the time of recording this podcast - was an Energy Executive in Residence at the Maryland Energy Innovation Accelerator (MEIA).

This conversation was a perfect first episode, setting the stage by covering topics like what a heat pump is and how it works, what the overall limits are on heat pump performance, how cold climate heat pumps work and what's driving cold climate performance, and a lot more. 

To listen to the episode, you can use the player in your browser or subscribe using the links below using your favorite podcast app:

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Key Links

Below are some key links talked about in the episode.

• NREL research on heat pump emissions relative to natural gas
• WARMTH Act (Maryland district geothermal)
• Dandelion Energy
• Pearl Edison essay on deploying heat pumps for LIDAC customers
• Heat Pump Review article on heating performance
• Heat Pump Review article on cooling performance

Podcast Transcript

The transcript was automatically generated and has been roughly edited for clarity, but may still have transcription errors.

Introduction

[00:00:00]

Nate: Hello, and welcome to the Heat Pump Review podcast. I'm your host, Nate Westheimer. Heat Pump Review is a resource for all things heat pumps. Our goal is to discuss heat pumps in a way that is accessible to people who are curious about the technology and how the technology can be best developed and deployed as the world transitions from inefficiently burning fossil fuels to efficiently heating and cooling our homes, our businesses, heating our water, cooling our foods, and even greening our industrial processes with an ever improving energy grid.

Today on the podcast, we're going to talk to James Ma . James has a PhD in material science from UCLA, where he worked on high temperature thermoelectrics for NASA Power Systems. James post doced at Caltech, JPL, and then founded a startup working on thermoelectric systems. [00:01:00] Most recently, James served as head of products for six years at Nalumbo where he worked on anti ice and PFAS free water repellent coatings with an application to improve the performance of heat pumps in cold climates. Currently, James serves as executive in residence with the Maryland Energy Innovation Accelerator, MEIA, and as an independent consultant for startups. It's in his role as a local climate leader I've gotten to know James, and I'm thrilled to welcome him to be one of our very first guests on the Heat Pump Review podcast.

James, welcome to heat pump review.

James: Thanks, Nate, for the intro.

Nate: Great. So today your experience and your expertise, we can go in so many different directions and full disclosure to our audience. We, we went back and forth on a couple different ideas because your, your expertise is, is so broad.

But given this is one of our earliest, if not our first [00:02:00] episode, we're gonna stick with heat pumps in the way I think most people are familiar with them in the way that I honestly cover them the most with heat pump review, which is residential applications of heat pumps with an emphasis, I think, and we'll see at the end, but an emphasis on some of the performance details and sort of better understanding what's going on in terms of heat pump performance.

Just to get started, I gave a bit of an intro to you, but any, any details you want to fill in there so that people know about you? You've been doing stuff in this space for a while I'd certainly love to know why you've stuck with it for so long.

James: Yeah. So I wouldn't say I came about, you know, I wasn't born a heat pump evangelist. I learned about heat pumps really was starting with the job at Nelumbo. it was a new concept to me. I think it's a new concept to a lot of folks. So I totally get that you're having this podcast to help educate folks about the, the kind of the misconceptions and the merits of heat pumps and where they do well, and where there's need for improvements around communication.

Um, it was a lot for me to get through and there's a [00:03:00] lot of misinformation online as well. So hopefully we can clarify some of that here. My background was really in the material side, but with everything materials, like the materials themselves kind of set the assumptions of what you can do, but they don't really, you know, they're not the end goal of why you're building something or using something.

So it's important to understand how these materials relate. My emphasis was on how. You know, we did, we did the coating and that how that affect heat pump performance, everyone thinks he pumps don't or can't work in cold climates. That's absolutely not true. Um, but we're working on new technologies to make that even better.

High Level Overview of Heat Pumps

Nate: Yeah, that's great. And I think we'll get to the, your comment about the cold climate, because as, uh, from my understanding, and maybe you'll correct me, but it hasn't always been true that a cold climate has been a space where heat pumps do do well or make sense. And I think you can educate us a bit on why things might have improved before we get there. Let's just do the high level. What is a heat [00:04:00] pump in the way that you think about it? And, maybe to kind of lead you into that: How is it similar to a traditional air conditioning system that people have had in their homes for a while now? And how is it different?

James: So this question comes up a lot. And I like to say that heat pumps are exactly the same thing as an air conditioner, except you can run it in reverse. And, you know, that's still kind of an abstract concept, so I wanted to break it down a little further. So, you think of your traditional AC you're actually taking heat from inside your home or inside your conditioned space and moving it outside- and outside is typically hotter, so you're taking, you know, you're moving against this gradient of heat, which normally thermo from the thermodynamics, heat will go from the hot side to the cold side.

So heat pumps or air conditioners, you know, to take heat from the inside where it's cooler and move it to the hot side. So the heat pump does exactly the same thing but in reverse. You're actually taking heat which is available in the environment, even if it's cold outside, uh, and moving it from the outside into your [00:05:00] home to keep it warm.

So they're mechanically basically the same. There's a few extra components. One of the key components is a reversing valve that basically flips the direction of refrigerant flow, but functionally in the, in the unit they behave the same way. There's other design considerations we can talk about when we talk about, you know, cold climate issues, but, you know, that's really the main difference.

So they shouldn't be mysterious. People shouldn't think of them as kind of a mysterious technology. They're really just an AC, and you just swap with what side is pointing inside and outside, and that's the simplest way to think about them.

Nate: Great. And this will help me not just the audience, when I think of my air conditioner unit, I have the, and this is a ducted type of system. So inside my basement, I have an air handler and outside I have the compressor and heat exchange.

And so when I look at that unit on the outside and air conditioning unit, I see metal that seems to have a lot of surface area to it. And, you know, it's all very delicate whenever you see, [00:06:00] um, you know, the heat exchanger that's outside then on the inside, it feels like a different physical sort of structure in there. It's a more compact set of, of coils and there's not those sort of prickly fan things on the side, like it doesn't look like, um, like a bristle brush, uh, around it. And so, you know, the question I have for you is, when we talk about it being a heat pump, like being an air conditioner in reverse, does that mean that the heat exchanger that's on the outside and the condenser that's on the inside. Do you need physical structures on both sides that now do two different things or Is the way that those two things are built actually appropriate for both heating and cooling?

James: so what you're describing reminds me, and you can correct me if I'm wrong, you're describing the fuzzy heat exchanger on the outside. That's really a Trane design. Do you have a Trane?

Nate: I do have a Trane unit Yeah,

James: that's like a Trane proprietary technology. Um, I forget what they call it. I think it's like a [00:07:00] spine coil. That's the, they have a, they have a whole product name for it and everything, but. Um, you'll find that most heat exchangers actually have the traditional round tube plate fin. The round tube plate fin is, you know, it's a copper round tube, and then you have aluminum fins coming off the copper tube. And that's like the most common design. And the reason why it's most common, it's easy to build. Um, there's a lot of, there's a lot of technical know how around it. The cost is low and, um, it does well for heat pumps because it's a way to compromise what exactly you're describing, where when you're trying to reverse the system, you're actually doing design compromises.

So the indoor unit, when you're cooling on space, you're having to deal with condensation on the, on your heat exchanger on the inside unit. You usually have kind of a sump pump or something to handle all that water that you're dehumidifying out of the room and making it more comfortable and you're having to pump that water out, but you're also having to get the water off the coil.

Otherwise your, your indoor unit would sputter and you'll start spraying water into the airstream and like, you know, water droplets or mist droplets would come out of your vents, which is [00:08:00] going to be terrible. And you've got mold and all these other issues. So they have to design the indoor coils to handle Water and condensation, the spine coils aren't designed to do that.

Nate: So on the outside, we don't care if that water just falls to the ground.

James: Yes, and no. Cause it gets into the problem of ice and then the heat clear the ice. And that's where like last company I was at, I was working on and all the design and points you're talking about here, you know, we're looking at heat exchangers and how do you start to balance the inside and the outside conditions?

And now they're more similar. You know, you're going to have to do a compromise design where some of the solutions you used in the past aren't going to be suitable for heat pump. So there are several differences, but again, I want to go back. Yeah. You know, it is still in the air conditioner. There are devils in the details. Compromises in design, but, um, you, your basic components are still there.

Nate: Okay, so generally speaking year from now I have my upgraded heat pump system. I open up the air handler. I look at the components inside. They don't look dramatically different, even though now it's doing two things instead of one.

James: Yeah. You'll have, you know, you'll have some kind of [00:09:00] fan that was a blower motor or blower, and then you'll have, um, some kind of heat exchanger and the two dominant types are either a round tube plate fin or something called a micro channel, which is if you opened up your car and you looked at the radiator or something close to that, or you have these long aluminum tubes, and then that's braced onto the corrugated aluminum fins.

Nate: Got it. Okay. I think people who read and listen to things about heat pumps have a general idea of how refrigerants work, but, and we'll get into maybe some of the details about the performance characteristics of different refrigerants later, but just to the initial question of how heat pumps work in general, how do you explain to the more lay person how specifically that heat gets moved?

James: Yeah. So, people who were kind of familiar with the space usually hear about a compressor and that's also like if it breaks, it's usually pretty expensive to fix. And so that's like the highest profile component of the system. And what it literally is doing is [00:10:00] taking refrigerant, compressing it from a gas into a, into a supercritical fluid or, and depends a little bit of design you compress it to a high pressure gas. That gas then is existing at a higher temperature.

That higher temperature, like in the air conditioner, can exchange heat from your inside to the outside. So it's carrying the heat it took from the inside. Boosting it to a higher temperature by compressing it into a higher pressure gas, and then you liquefy the gas by rejecting that heat into the outside environment.

And that, you know, then you have a liquid in your heat exchanger on the outside, or in a lower pressure gas, and then that gas gets expanded through a valve. And that, that sudden change from high pressure to low pressure causes rapid cooling and liquefaction of the gas. Sorry, rapid cooling of the gas. So you'll kind of flash the gas.

You'll see it most commonly if you open up a soda bottle. That change from high pressure to low pressure, you can kind of see it at the lip of the bottle. You'll kind of see some condensation droplets, and that's the [00:11:00] same, or a related cooling event.

Nate: Okay. Before we get into some of the cool, no pun intended things around performance, and now that we've described an HVAC heat pump system. How do they differ from the other applications? Let's just take residential applications of heat pumps. We have a heat pump that is removing the heat from our refrigerator and our freezer into our kitchens.

We have heat pump ideally heating our water, taking a heat out of the utility room and putting it into water. I just bought a dryer that is a heat pump dryer. So how does that HVAC system you just described I imagine in many ways it's very similar so why don't you focus on how it differs in terms of how it needs to perform in the operating environment, then then some of these other applications of heat pumps.

James: Yeah, so let's use your example of heating water right off the bat. So heating [00:12:00] water, heating water is very, very difficult. It's very energy intensive. That being said, it's a great use of heat pumps because heating water is just right behind space heating in terms of the amount of energy a home would use, so with electrification and the need to electrify for to avoid climate change, one of the worst effects of it, heating water is great.

It would differ in not a whole lot. You're just having a copper coil. You wouldn't have these fancy fins. You just have kind of a copper coil that lives inside your hot water tank, and then it would just burn . Run like an air conditioner. Instead, you're dissipating that heat into the water, and that's heating your water up.

The exact temperatures might be slightly different in terms of what the temperature of that heat exchanger is to optimize for between kind of the heating rate and the power and the efficiency of the heat exchanger. But they're fundamentally the same thing with a slightly different heat exchanger.

You'll have backup systems on some heat exchangers with additional electric heaters. But that [00:13:00] also exists in space heating heat pumps as well.

Nate: Right? Well, part of the question, and this might get us a little bit into the refrigerant discussion prematurely, but just on this topic of how they are different, I've noticed that there are very different sets of refrigerants that are used. So while it's, it's doing a very similar thing, there must be something, some characteristics about these other applications where, for instance, I think it's isobutane for my dryer, um,

James: Oh, I'm surprised. I didn't realize they had that.

Nate: Oh, no, sorry for my refrigerator. It's isobutene. Uh, but it is another I'm blanking on what the the other flammable, uh low GWP uh, yeah for for the dryer, so um We'll talk about CO2 later, but the only residential CO2 Case that's out there today is is a water heater. So I guess Curious if there are, um, if, if the [00:14:00] differences in refrigerants being used across these different use cases are instructive about, um, how various heat pump systems differ.

James: yeah, the simple ways to think about it is you have to think about both the temperatures and what you're operating, and then the temperature differential. So for a typical refrigerator, you're operating inside a condition space, let's call it 70, 80 degrees F, and you're cooling to a much lower temperature, you're talking for your refrigerator compartment, you know, let's call it 35 to 40 F, the heat exchanger itself somewhere closer to probably you know, 30 to 25 F. Um, depending upon your refrigerator system, you may only have one heat exchanger for your freezer and your refrigerator. So you're really having your, your freezer evaporator or so the indoor heat exchanger for the refrigerator compartment being negative 20 F. So you're driving a really large delta T, between your indoor [00:15:00] environment and then that low temperature.

Nate: So delta T is this difference between the two spaces, the, target temperature of one space and the, Space that you're either trying to draw heat from or reject heat into

James: Absolutely.

Nate: So that that would be on the refrigerant side. Is there anything from an engineering side that then has to be like major? I'm sure there's some differences due to the refrigerant that you've chosen or due to the simply the You know, something that has to operate submerged in water versus otherwise.

But, but broadly speaking, are there, I imagine the components are, are very similar or, or are they not?

James: they're very similar in the sense of you always have the four key components on any AC, refrigerator, heat pump system. You'll have your heat exchanger outside, your heat exchanger inside, a compressor and a valve, or a device to, you know, meter, throttle. Basically cause that expansion of the gas from high pressure to low pressure.

That's, in any system [00:16:00] you have all four devices. You might have more devices depending on what you're doing, but you will always have the four devices. In a traditional, what we call like a vapor compression heat pump, where you're taking refrigerant that's a vapor, compressing it, and then moving heat around with that.

What gets really different is the heat exchanger design. We touched on this before. So in a refrigerator environment, you're having lots of moisture from fruits and vegetables and whatever else you're shoving in your refrigerator, and that builds up a lot of ice. So these refrigerators typically have very low Number of like heat exchange features or fins, they'll have big gaps in the heat exchanger that allow for ice to build up and air to continue to flow even if ice is building up.

The trade off is you'll have low heat transfer efficiency because you're having fewer of this surface area of the, of the, of the metal available for heat transfer to accommodate for ice. Then, you know, you're having a less efficient heat exchanger. And you're constrained by how big of a heat exchanger you can put into your refrigerator because they'll start to push [00:17:00] against the dimensions of your refrigerator.

You don't want your refrigerator to be just one giant heat exchanger. You want to maximize the amount of, you know, stuff you can stuff in your refrigerator.

Nate: Ice cream.

James: Yeah, absolutely. So, so people will have to like make those design compromises, the OEMs.

Nate: And when you're talking about this ice buildup on the heat exchanger, you're talking about, this is outside the machine. This is,

James: This is inside the machine. So like in your freezer compartment, um, one of the problems is, you know, you'll have a, you know, these frostless refrigerators that they were marketed as, but what they really have is, you know, they build up frost and they'll have an electric heater inside your freezer. And they'll melt the frost by running a pretty high power electric heater. And that's true of a home refrigerator, and true for a vast majority of commercial refrigerators as well.

So you're dumping a lot of heat into that space, and then you're vaporizing all that water, and then when it refreezes, sometimes you see ice on your ice cream, or frost. I mean, that re vaporized, refreezing event is causing some of that formation of frost on your other food and inside your freezer compartment. [00:18:00]

Nate: Okay. So you have these different systems and with a HVAC system that we were discussing earlier, that condensation can drip, you have a pump, that pump goes to your utility sink or into a drain or out or sometimes through a pipe that goes directly outdoors. But in other design systems we have to get a little bit more creative because we're not going to have the same ability to dump that moisture.

James: it's not a liquid anymore, it's a solid.

Nate: it's a solid, Oh yeah.

Limits of Performance

Nate: Well, Let's move on. I, I'd like to talk a little bit about performance. I know a lot of other people who are newer to the space and have come not from your background but more from a software engineering background it's easy for us to get very hopeful about performance gains that we can see in the future. We come from a world of Moore's law, where we've seen storage shrink in [00:19:00] size. We all had a hundred megabyte Iomega zip drives in the nineties and now the little micro SD card in my drone is super tiny and has 64 gigs. We're seeing this with obviously chip design with AI. And so we see that as a technical pattern. And then we look at solutions like heat pumps and without knowing anything about them, we kind of hope, Oh goodness, this is, this is something that's maybe going to be consuming two kilowatts at, at a time but I wait maybe wait 10 years and, and it's going to be half that, or, or a quarter of that. So help set some expectations around performance and heat pumps. And I know let's just go back to residential heat pumps to keep things simple. where have we been?

Where are we going in terms of in terms of efficiency

James: yeah, it's, I mean, you can look at the Department of Energy's website and they started regulating heat pumps and air conditioners. Actually not that long [00:20:00] ago. I think that I was looking at it earlier and you know, one of the standards they use is SEER, and you'll see that on your unit, I think it was like a SEER or 10 about in the 2010s, and now we're up to about a SEER 14 as a pretty recent rule.

Nate: So it's, so, so the standards have gone up 40% in, let's say, fif, you know, right. About 15 years.

James: yeah, and one of the hard parts of the work that's when you just say the standards have gone up 40 percent is that the way they do the rating, it's a little complicated and it kind of obfuscates a little bit of it. You look at the engineering reasons why you get it, but then for an average person, if they see a 40 percent improvement, they're not going to see necessarily a 40 percent reduction in their energy bill.

So what the SEER is, is the Seasonal Energy Efficiency Ratio . So it takes, you know, weather patterns across different regions of the U. S. And it'll estimate or guess how much cooling you'll need or how much, for SEER applies only to cooling, uh, how much cooling you need.

And it'll calculate the system's [00:21:00] efficiency. Which is the coefficient of performance. It's for every unit of electricity you use how much units of how many units of energy can you move around from the inside to the outside? So that's COP.

Nate: that's COP. and you mentioned SEER and we can say that if we just take off the S the EER is, is more equivalent to the, to the COP. Is that correct? And since it's more of a pure, um, the, it's a more pure ratio of, in this case, cooling and for our audience, on the site, we'll have, by the time this podcast goes up, we'll have a deep dive into EER and SEER And the historical trends there and the definitions and the equations for them, but essentially, and we already have this, the HSPF , which is the heating equivalent of it.

Um, where again, you can look at it more of as a point in time. performance metric, or when you see the [00:22:00] S in any of these, it means seasonal. It means averaged, averaged out. So what you're just talking about there was a cooling rating. And I should have said this earlier when we were talking about it going from 10 to 14, that that's a, uh, that's, that is the SEER.

That's the seasonal, the averaged, uh, efficiency rating for cooling.

James: Yes. So it, so what that kind of translates into is roughly like a COP of three. Ish. I'll vary quite a bit. I mean, I'll vary a little bit. If you look at the market today, they have released units from the big brands of SEER up to 28, I think I've seen, or maybe even low thirties. I haven't looked at the most recent one. So they can easily double their SEER ratings today if they wanted to. The question is it comes cost prohibitive. So we were talking about, you know, the, the upper ranges of technology, I would say is the ratings can mean even using the traditional ratings that manufacturers know how to do it. It's just, it [00:23:00] becomes a barrier to adoption.

If you, you know, if you're trying to push through these really high efficiencies,

Nate: And then another difference, and maybe to get to my question about theoretical maximums, because that's, that is sort of my curiosity here.

HSPF2, SEER2, they're taking into account the entire end to end system. So a lot of that gain, the reason why you'll see something out there that is, a mini split with incredible efficiency versus a ducted system with lower efficiency isn't necessarily because the compressor and the refrigerant are That much different or worse.

It's because you have a ducted system on the other end of it with a, with a big blower motor that is doing a lot of work. And so they are taking into account the energy, not just to move the heat in the refrigerant cycle, but to also move that conditioned air.

COP is just looking at the compressor, you know, just [00:24:00] looking at the components of the, the heat pump itself rather than the end to end. So maybe let's just talk about COP for a second. And you talked about it being roughly around three to four today: are there any theoretical maximums of like, this will never, like, there's something about this that means that we can never see a COP of a hundred.

James: I don't know if that's been like the most important question ever

Nate: interesting.

James: in

Nate: makes you say that?

James: because we're so low in COP today that to me, it's more about solving the, the, the design question of how do you get higher COPs into a low cost system because it exists already. Um, and it's just a question of how do you make it accessible and we don't make an accessible, then it's not really worth anything.

Cause no one's going to deploy it. So, I mean, like I said, we see SEER 30 ish units [00:25:00] today, but I don't think anyone's really buying it or it's going to be a really small minority of people.

Yeah,

Nate: let's, go into that. So I want to take away again, kind of the cost component. There's, there's a bunch of cost components here that are about installation. They're about some practical things about just ripping up houses and putting, you know, puncturing either walls or floors or whatever, ceilings, whatever you're doing.

Uh, you know, putting all that aside, just again, back to kind of the raw components and, and more on the kind of physics of the thing, what is it that you see in them that is making them so hard to keep small and simple, but also drive up performance. Like, where are we running into? Where does the industry from what you've seen run into those challenges?

James: Yeah. I would say, you know, the challenges are it's, it's a compromise design system and you're trying to do a lot with very. With a very different competing interests. I'll give you one example, um, for the heat exchangers, you [00:26:00] really would want the biggest heat exchangers you can possibly do make. And that would dissipate as much heat or gather as much heat as you possibly can.

And, you know, you can make these ginormous heat exchangers, you'll have great efficiency, um, from the heat exchanger side. But the flip side of it is as you're making heat exchangers bigger, you need more refrigerant. So you're pumping your systems with more and more refrigerant inside. That creates more work for your compressor.

So you take some losses there and you're just dealing with more refrigerant. And, you know, people don't want to have more refrigerant in the systems because they have really high global warming impacts from the refrigerant themselves. So you're compromising a lot of design factors, um, when you're, when you're building the systems and that's been, you know, and they're asking them to do a lot when they live in the cold and they exist in the snow.

And then we turn them on every year and we expect them to run. So they're built for reliability.

Nate: Mm

James: They're built to be able to, you can install them and there are [00:27:00] constraints on size and cost. So, a lot of technology exists. It's just difficult to implement, um, in a, in a cost effective way, not to say that the industry can't do better, not to say that, you know, and the easiest one, I think that you'll see a lot of activity overseas, but not less so in the U S is a variable speed systems and inverter compressors.

Um, that's basically become default in Japan and countries like China. Um, but in the U S is still a minority of units have variable speed systems. So most of the U. S. air conditioners and heat pumps are either on or off. You hit a set point, you turn it off, and then when you go above a certain temperature or below a certain temperature, your system will turn on again.

And that's really inefficient. Um, you want to, and it's really inefficient, it's really, it's actually not the best from a comfort, comfort perspective. That's kind of an easy solution now, um, they know how to do it, but it's still, you know, I, I recently installed a heat [00:28:00] pump and, you know, there's a significant cost adder to wanting to buy and to knowing to buy an inverter

Nate: hmm and and yet it's a huge driver of those efficiencies

James: The systems are designed and, you know, the installer will decide the system to operate under the maximum load conditions, like middle of August, middle of July, when it's the hottest for air conditioner, you'll need more air conditioning in that scenario. But in most circumstances, you don't actually need all that power from the air conditioner

Cold Climate

Nate: Okay, moving us to Cold climate. We've had this gain in performance over the last decade. Plus, uh, as you just were talking about, it sort of come from things like variable speed compressors and just. You know, the, the stubbornness of engineers trying to make things better while keeping things cheap and easy to maintain.

But one area that seems to have really dramatically changed [00:29:00] is in the ability of, of heat pumps to operate in our coldest climates. And in fact, there's a whole, you know, cold climate rating that heat pumps can get.

Where has this gain come from? Why all of a sudden does it seem like, maybe 15 years ago, we would have said to somebody in a cold climate, maybe don't get it, or maybe get auxiliary heat with your system. But today we can talk to somebody in Minnesota and say, you don't even need auxiliary heat. Talk to somebody in Maine, tell them, You can absolutely get a heat pump. So where has this improvement come from?

James: I think a lot of it has come from traditional engineering design. Um, so when my past company, we were trying to overcome that barrier, allow for more simple, simplified designs and. What I mean by more traditional engineering designs like these Mitsubishi Hyperheat and some of the Hyperheat units or a lot of the Hyperheat units, you'll [00:30:00] start seeing them be a lot bigger than a traditional, um, so these Mitsubishi you're talking about, a lot of them look like kind of a mini split, that rectangular box that will live outside of homes and buildings, um, the, the Mitsubishi Hyperheat ones are just physically larger.

Um, We have bigger fans, more heat exchange area, and we talked about dealing with ice, and they're just designed to operate and provide enough capacity. I think their rating is down to 5F, so they claim full capacity down to 5 degrees Fahrenheit. And one of the ways to do it is you just make the system bigger, but then you don't run it at that peak power You just run it at a lower power point most of the time. So your system is just more efficient

Nate: So it wasn't some big discovery. It's more like some big compromise,

James: I think it was also a lot of little things, and I don't want to discount that. You know, a lot of engineers worked really hard to make it work and make it, you know, it's not that much more [00:31:00] expensive. I mean, in an absolute, like, percentage sense. Do you think that you can maintain this performance to 5 degrees F or before?

You know, there's normal tapering off of heating capacity as you, as you get to lower temperatures. Because there's, without, without those designs in mind, uh, you're not able to extract as much heat, because there's, from the cold environment. So at 5 degrees F, there's a lot less energy in the environment than there would be at

Nate: those coefficients of performances that we were =talking about up in the fours, that's not happening at, at negative five.

James: Or at 5 F, no, no, no, they don't guarantee the COP, but they guarantee that at least you can get

the heat

Nate: that you, you signed up for at that,

at that

James: Yeah, COP where those temperatures are closer to like 1. 5 to not 3. 4, which you'll often see for heat pumps. But that's at a much warmer temperature.

so, we were trying to get around that by having a coating Yeah. So let's get into what you were doing. So a lot of [00:32:00] it's just like stubbornness of design, making them bigger, but you spent a good amount of your professional career in a more, I guess, a less obvious place.

Nate: So talk a little bit about that, What you were working on and the role of these coatings in helping something work in extreme temperatures.

James: Yeah, we're working on a, uh, a nanostructure ceramic coating that would apply to the outdoor heat exchanger. And what it would allow you to do is, uh, slow the accumulation of frost. And then also when you do build up frost, when you need to defrost a unit, it would rapidly defrost by shedding the water droplets.

Uh, the company was called Nelumbo, and it was named after, I think the, gosh, I always mess this up, but the family of the lotus plant. Family or genus. Um, someone correct me. And, um, it kind of has a similar behavior where you look at a lotus leaf and you drip water droplets on and you'll have this like super hydrophobic effect.

Um, and that's is not a new idea within the space, but the [00:33:00] ceramic coating and the way we were applying it was a low cost way of applying it to these really complicated. heat exchangers. They have all these little nooks and crannies, and we could apply it via a low cost chemical dip method. So we're working on that.

And by allowing you to have these anti ice coatings on the heat exchanger, you can really cram more heat exchange surface back in. So, one of the compromise designs for heat pump versus air conditioners is that they'll make the heat exchangers on the outdoor heat exchanger have lower surface area, or lower, the term is fin pitch, so the spacing in between each little metal feature on the heat exchanger would be much smaller in an AC.

For a heat pump, you needed to increase the spacing so the water would drain. Otherwise, I'll have this like capillary action from the water, and you'll build up a bunch of water on the heat exchanger, even if you're defrosting and melting the water or ice into water, that water gets stuck there. With the coating, we slowed down the accumulation of [00:34:00] frost and then also allowed the water to shed off more quickly so you can defrost for shorter periods of time, allowing you to design more complex heat exchangers on the outdoor unit, which will lower costs because then you can make the system smaller again.

You can use less fancy compressors and, um, make heat pumps, you know, more comparable, just a regular

Nate: Yeah, this was a, so this was a part that wasn't obvious to me at first, which is when we talk at the top of the episode about, Oh, heat pumps are just an air conditioner, but you're running them backwards.

But in reality, when you're running an air conditioner And the, heat exchanger that's in the outside elements. Yeah, it can get hotter out. It can get hotter out. It can get hotter out and it's going to get less efficient as it gets hotter out, but nothing really physically is going to change about that device

but on the flip side, when you are in the dead of winter and there is frozen precipitation, and you are running a very, very cold [00:35:00] in order for you to extract heat out of, cold air, it means that the Refrigerant needs to be colder, than that air you are at, you know, you're dealing with a much harsher operating environment than the, the AC unit. it actually becomes a physically different unit because of the way that precipitation can affect the machine

James: Yeah, it, we're asking them to do a lot. Uh, you know, they, they, they'll have to operate at a plus a hundred degrees Fahrenheit and then at like, you know, negative 10 or zero degrees Fahrenheit. So these systems are asked to do a lot. Um,

Nate: and so these materials on it and what you were working on just basically help them do their job without being encumbered or without being, slowed down by the elements, that they're in, Namely ice.

James: exactly. So yeah, dealing with that big ice problem.

Nate: And, so do you, and obviously there's, there's probably a whole nother episode about [00:36:00] being a startup in a category where you have giant behemoth companies that have their own engineering teams and, you know, I'm sure they select technologies, not just because it's better, but because of intellectual property rights or because of, you know, how they can utilize a specific plant they have in the middle of some state. So they might choose one technology over another simply for economic reasons. so taking aside the experience of being a startup in this space.

Is this an area that you see a lot of future performance gains you know, coming from, is this still a, an area ripe for innovation?

James: Yeah, and you'll see the innovation in the space is coming both domestically and from international. Um, one of the biggest players in the field is, uh, Daiken, and you'll see in the Daiken units in Japan, for example, which has a long history of heat pumps, um, they'll have different fin designs and different system designs.

Um, and some of that's [00:37:00] been getting cross pollinated back into the U. S. Market. Um, the organizations are large enough where, you know, one in your left arm may not fully talk to your right arm type of situation. Um, but there is, and they just have different markets where you're dealing with, you know, Japan has a much more of a mini split market.

Whereas in the U. S. you're dealing with those big ducted units, those kind of rectangular or sorry, the more square boxes, um, that you'll see on top of roofs or outside your home. And so there's, you know, there's some technology transition translation that needs to happen. There's different fin designs that they have today, different coatings already they're using to kind of deal with the ice and water problem on heat pumps.

Nate: Cool.

James: I see this as a continued research and development effort. You know, a lot of other ways to solve the ice problem that people are tackling it from a, you know, looking at the aerodynamics of ice, the fin geometries, the fin spacings. How do you then, you know, design [00:38:00] better mechanical systems, to deal with ice. So people are, it's a known problem being from material science background our, our approach was let's use material science and chemistry to help deal with how water and ice grows on surfaces, which is a surprisingly complex phenomenon, which I didn't appreciate until I started doing work in this field.

Um,

Geothermal/Ground-Source & Water-Source Heat

Nate: Well, I have one more line of questioning but I also want to have you share a little bit about what you've been working on more recently. One thing that we did not cover is, uh, you know, we're just talking about air source heat pumps. So we are trying to either reject heat into air or extract heat out of air. There is, you know, geothermal or sort of ground source heat pumps, and then in some condos and other types of buildings there's even water source heat pumps and, and not just in, in the sort of those environments, but I know some, some [00:39:00] big, big, you know, universities have tried to do water source heat pumps in, in lakes. It's just to say that one vector of, of potential innovation, it seems like could be in taking some of the advantages, that using a water source or a ground source brings to, and, and finding ways to miniaturize it or bring it closer to kind of the everyday consumer than it is, is today.

Have you seen anything in that space? Are you optimistic at all about anything that you've, you've seen in terms of people trying to essentially make us less dependent on, on ambient air for the heat exchange.

James: yeah, I think that the big challenge in any of those applications is having that water or ground source and Um, you know, the one high profile company was Dandelion Energy , um, I forget when they started, but they've been around for a while now, and they were trying to [00:40:00] adapt some of the drilling technologies that were developed around, you know, really drilling and fracking to miniaturize drilling so you can drill in the suburban neighborhood and install a well, or essentially a well, but this is like a thermal well, and minimize the footprint and the, uh, the challenges associated with drilling and in these complex environments in a built in a like, um, in a green space where you can build, you know, whatever you want to build District Heating makes a lot of sense.

That's kind of what you're referring to, where you can use a ground source heat pump generate a lot of hot water. And, you know, use that to heat many, many homes. You have a lot of efficiencies from just being a water source or ground source, and they have a lot of efficiencies from being like centralized plants, and you can sub meter these systems, but it takes a degree of coordination and cooperation. You use, it's a lot less common in the U S you might see it in apartment buildings, or you might see it at a university dormitory, but in the U S where everyone's [00:41:00] home is kind of singular, um, it's really hard and expensive to build these systems.

Not to say it can't be done, but it's a, it's a kind of a social and business challenge versus a, uh, any kind of technical challenge in that space.

Nate: Yeah. And, and I'll put this in the show notes and one of the cool innovations in bringing ground source heat to more people are things that are already happening in Massachusetts and just got passed as law here in Maryland called the WARMTH Act , which will help utilize existing utility rights of way that are bringing gas lines into people's homes and replacing that with a ground source heat .

Another area of innovation I also wanted to ask you about, I've seen in more industrial type of settings is when different systems are combined. So where you have, where you have one bit of hardware that moves the temperature from X to Y, and then you have another set of [00:42:00] temperature that's, you know, especially tuned to move it the next bit. I'm not sure if you're familiar with these, these types of systems or not.

James: You're thinking about like cascade

Nate: Thank you. Cascade systems.

Um, do you, do you think there'll ever be sort of a role of that type of approach in, in more residential applications, or is that more reserved for more extreme applications?

James: Yeah, I've only seen them in the more extreme like commercial or industrial settings where you're trying to produce like a deep freeze like deep freezers today use cascades commonly And that goes back to that problem of like refrigerants relying on a certain delta T and T. You'll have two different refrigerants or two different systems that are optimized across two different temperature ranges.

And then one rejects heat into the other. So instead of directly to the air, you'll take the heat from the low temp side of the cascade, reject it to this intermediate temperature, which is the low temp side of the upper step, and then that will reject it to the [00:43:00] environment. Um, so for a home application, you can, it just gets really expensive and it goes back to, you know, it's a lot of equipment to put in more things to maintain more things to break.

Um, so I don't really see that in the home application. I do think there's definitely needs to be, you know, we're doing a lot of investment now and he pumps and that's great for electrification. But the feature is that we need to address the challenges associated with refrigerants directly. So this means, you know, lower global warming, potential refrigerants, safer ones, or a shift to solid state cooling technologies where you're not having to deal with refrigerant leakages. Um, a lot of the solid state technologies are pretty early. Um, I think they're promising pretty early.

Integrated Systems

Nate: And how about, I mean, similar to talking about cascading systems, and I get for a given system, how, how it could expand the complexity, the risk of leakage, the cost but we are living in a world where I have a [00:44:00] refrigerator, I have a dryer, I have an HVAC, I have a hot water tank.

And, and so we're, you know, going to be in a situation where I have four to five heat pumps doing different tasks, but doing very similar tasks in my home, some of which are actually complimentary because, you know, My refrigerator needs to reject heat and my water tank wants that heat. will there ever be a day do you think where instead of buying five different heat pumps that are specially tuned to be very efficient in those operating conditions to instead it'd be more efficient to just have sort of one unified system . That one day I will choose the Mitsubishi or the Trane platform, I'll have a unit outside something on the inside that sort of just goes out to all these different appliances.

James: Yeah, I think fundamentally the [00:45:00] answer is, it depends on all the incentives that we have, you know, in the U. S. we've enjoyed like decades of relatively low cost energy. So we really haven't cared. So we said, yeah, just slap it another gas system and whatever. It doesn't matter.

Whereas in other markets like Japan and Europe, you'll see more of these systems common.

I think gonna go by the name of the hybrid water heating system. Um, the idea is that you have a single heat pump, you have a water heater tank, the heat pump will heat water to provide like domestic hot water, and at the same time provide enough heating to, you know, provide, uh, like radiator heating. So a lot of older homes may have, which are also common in Europe, uh, you'll have hot water radiators in the past or fired by, you know, gas or coal or, you know, choose your fossil fuel choice, heat a bunch of water and then you just pipe that hot water around your house.

Some European homes have, you know, taken the heat pump and replaced whatever fossil fuel source and, you know, provided both hot water and home heating. I think that makes a lot of sense. [00:46:00] It'll take a shift in kind of the American mindset, a shift in the American incentives. Um, you'll have to do a lot of plumbing on a traditional American house.

Um, it's not impossible. The technology exists. Uh, it's just not, it's just not very widespread or known about in the US I think that's actually promising here in, in like if I were to wave a magic wand and what I think makes a lot of sense is you had tanks that could store energy like hot water or cold water and that would live in your garage or basement or utility room and your heat pump can tap those sources and balance that load in your house.

Um, it takes some, a lot of technology in the smart home side and a lot of like new ways of thinking about how to build homes and manage heating. But the, you know, with the cost of energy still being relatively low in the U. S., um, compared to, you know, it's externalized costs on the climate and the environment, and compared to just other markets, the, it's hard to justify the cost for people that are, you know, we're facing a lot of, especially these days, like a lot of inflationary pressures to just [00:47:00] ask people to pay more for these really complicated systems

Nate: Sure. And, and and the approach of, uh, that we have today of each being their own independent system to that point on cost, it means that many more people can afford with the cash that they have without taking on more debt can afford a new dryer, or a new water heater independently, but if you would tie all these things together, they would look like the way that HVAC is today today, plus, plus, which is very expensive. Now, all of a sudden you're needing financing, you're delaying the purchase. 

James: people don't plan ahead. I don't plan. Like I replaced my dryer when it broke. I didn't replace my dryer to try to sync up with a water heater replacement to sync up with like a heat pump replacement for my

Nate: Yeah, no, very, very, very hard.

Closing thoughts from James

Nate: So, there's a good part to pivot to the last question and feel free to share as much as you want. You're an executive in a energy executive in residence, which means that you're helping a bunch of [00:48:00] startups on, on what they're working on here in the, in Maryland.

but you're also thinking about what you're going to do next and you're taking, you know, your interests and your applications to the extent that you're willing to share, with the audience what have you been wrapping your head around lately. What's next for James?

James: Yeah. And yeah, thanks for asking about that. So I'm helping with, uh, MEIA, which is a part of this, uh, I didn't get their structure clarified, but you know, they're affiliated with the state, they have some state financing or free state funding and what they're trying to do is, you know, build the ecosystem innovation within Maryland.

You know, Maryland has, you know, a few very powerful institutions, generating a lot of great research, but it's a different skill set and a different, you know, effort to build. Technologies and companies out of that. So that, you know, more of these jobs and more innovation stays within Maryland or, you know, the, the mid Atlantic region.

Um, I'm originally from California. I grew up in LA. Um, And, you know, the private company I [00:49:00] was at was in the Bay Area, and you think of innovation and, you know, job growth and, and really overall economic growth, you know, it's come from these clusters of, you know, you attach them to universities, you take, you know, brilliant scientists and engineers and you get their great ideas and you match them with folks that have some business experience and know how to translate technology out.

So I'm helping several companies, um, largely affiliated with the University of Maryland for two companies. And helping them work through their business ideas and really get that from just, you know, the laboratory bench, you know, create business plans, create financial models, create, how did you start thinking about your customers?

I think, you know, engineers love engineering. Uh, I say that as an engineer or a former engineer, uh, But it's really, that's not the important part. It's really like, you know, you're thinking about the customers. So taking that approach to, you know, to talk to these engineers, to how to then translate technology that's meaningful for, [00:50:00] for the market.

So, you know, one of the companies, you know, I alluded to, um, is actually working on solid state cooling from the university of Maryland. Um, I mean, the top technology is really interesting, but it's a hard field. Um, My prior life was thermoelectrics. Uh, it was also, could be run as a Peltier cooler. You'll see them sometimes in portable coolers.

You can plug into a cigarette lighter in your car. Um, kind of dating myself there, but, uh, you can plug it into the 12 volt outlet in your car and you can provide some cooling inside your car for the, you know, for drinks or whatever. Um, but they suffered for a long time from low efficiency, so you don't see them widespread.

Um, so this, this new technology from the University of Maryland has an opportunity to kind of use a very different, uh, very different physics to, to drive much higher efficiencies and low cost in solid state cooling. And that technology is really promising and really interesting. Um, you know, but it takes a lot of [00:51:00] investment, a lot of work to get new technologies off the ground.

You know, we're talking and then they have to compete against a market that's existed for over a hundred years and had a hundred years of hundred plus years of R and D, uh, you know, these vapor compression systems, you know, are really old. A lot of people have worked on it for a really long time. So there's a, and you, you have to compete head to head against them.

Nate: Right. Right.

James: Uh, and then separately, my interests are around, like, thermal storage, and I kind of alluded to it. Um, you know, I think there's a lot of inefficiencies like what we talked about, where you're running a lot of systems and wasting a lot of heat, and then we spend most of our energy in a home, so roughly a third of all energy use in the U. S. is for, is in your home, and over two thirds of that is for space heating and water heating, um, You know, you have photovoltaics that can take sunlight, convert it to electricity, and then make heat, which is, you know, that's a lot of steps in between. And what kind of [00:52:00] interests me is how can you, you know, shortcut that and go from directly from the sun's heat, which, you know, we feel every day when we walk outside, and use a more efficient pathway to convert that to heat, and then store that heat so it's useful for whenever we need it.

Um, heating will address, you know, over half of that, um, energy demand in our homes. And the technology can be pretty simple. And some people, you know, DIY it, but how do we make that, uh, more widely available within the U. S.? So that's an idea I've been exploring on the side.

Nate: that's a super interesting and I think, we could spend another hour just on, on that topic. And so I would love to do that one day with you. so before we leave things for today, is there anything you'd like to leave people with any parting thoughts in terms of anything that we didn't cover that you really wanted to make sure you share,

James: Yeah, so I think a lot of, like, You know, kind of addressing the first topic of misinformation, you know, people are saying heat pumps won't work. You know, that's not [00:53:00] true. They can't they work in most environments unless the most frigid environments you may want to consider an alternative. The caveat to all of this is that they're facing pressures and electrification is that the cost of electricity in the US has been going up pretty dramatically, especially in certain regions like California and Maryland. I think we pay something close to a 10 to 15 cents a kilowatt hour. But in California, the pain upwards, like 40 to 50 cents a kilowatt hour. Um, so that is a barrier to electrification and it does, you know, it creates this negative incentive toward electrification that will, you know, that it's a much more complicated problem that at the grid level and at the policy level, people are going to have to address.

Because it gets into the problem of it. People are replacing their systems with heat pumps and then their, their energy bills go up, or it's a possibility that energy bills go up, um, because of the relatively higher cost of electricity versus natural gas. Um, and it's all goes back to the incentives within the system.

And [00:54:00] the challenge in the electric price is that you're not paying more for generation. Electricity. They're paying a lot for dealing with the cost of all the wildfires within California and what, and then the utility is passing on those costs to the rate payers paying for like wildfire management.

Which gets into this more complicated question of the grid and how do we fire grid? How do we not leave people behind? Um, you know, these heat pump units are putting a lot of load onto your local, your home grid, your, your electrical panel, and a lot of people don't have newer breakers or newer electrical panels that can handle, you know, the multiple breaker spots that, uh, the heat pumps are going to need.

So I don't have a good answer for that. I just know that that's a thing people are thinking about.

Um, but.

Nate: Yeah, well, it's, and it's a reality that we have to deal with. And I think some of the things you said about how in certain places in the country, it can be more costly to change fuel [00:55:00] sources. I'll link to it again in the show notes, but the, the startup Pearl Edison in Michigan recently did a blog post that I think was good, I told them that it made me squirm when I read it because, you know, I, I, hate reading that We're recommending some people either get auxiliary natural gas heat for their heat pump system or not get heat pumps at all, but I think you're calling out what they're calling out, which is there's some hard realities about the, the costs. Obviously, ironically, the more people get on heat pumps, yes, it will increase load, but they are much more flexible. And so we can also, they can help alleviate some of the demands on that local grid and hopefully reduce some of those those local distribution expenses.

Um,

James: It's not an issue yet, uh, it is an issue people are aware about, so I'm not discouraging people from getting heat pumps from a climate perspective, absolutely, you know, whether your grid is a clean grid or, you know, a mixed grid, um, you're, you're seeing a CO2 savings over the lifetime of the heat [00:56:00] pump. The challenge is you're installing these systems for like 15, 20 years. Um, so if you're going to have to replace a furnace in the next couple of years, or in the next decade, you should probably, you should definitely replace it with a heat pump. Um, it comes in the policy question of how do you align incentives?

And that's a bigger, much more complicated, complicated question. Um, but it is a real concern that we can't ignore from people that are heat pump advocates that, you know, the reality on the ground is there doesn't need to be some calculation of, like, if your price of natural gas is so low and artificially low, or maybe, you know, if you externalize all that cost, um, versus the electric grid, which then internalizing all the costs of wildfires, partially induced by climate change, you know, you're, you're, you're competing against unfair scenario.

And then how do you restructure your your, your, your policies so that you're not just incentivizing electrification, which is important for getting off the fossil

Nate: absolutely. Yeah. And I will [00:57:00] link again in the show notes, you're mentioning how, even if it's more expensive to, to, to use heat pumps in every single zip code in the United States it is no matter what grid you're on, no matter what temperature your average season is, it is more energy efficient, less CO2 and other gases for you to do a heat pump and NREL Eric Wilson at NREL, the National Renewable Energy Laboratory, uh, published a great paper on this , um, earlier

this

James: Yeah. You're talking about, I think we're talking about the same

Nate: Yeah, so I'll link to that so people can read that, but I think that is, that has been, I think, a very effective and useful document to show people when they, talk about, Oh, well, my grid is a little bit dirty around here we have a lot of coal. Well, yes, that's bad, but what's worse is, is still burning a fossil fuel in your home.

James: Absolutely.

Nate: Well, James, this is awesome. I feel like every time I talk to you, [00:58:00] I could go on for hours and hours and hours because, uh, you bring up another topic that I'm interested in.

I certainly would love one day to, to dive deeper into what we just covered in terms of your interest in not just converting the sun's energy into electricity directly to then be used for a heat process, but instead to just take much more of that energy and put it to good use, I think it's a super interesting topic, and one for another day. So thank you very much for being on, uh, Heat Pump Review.

James: Yep. And thanks for having me on.

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