You're listening to A Climate Change. This is Matt Matern, your host. I've got Dr. Roland Horne from Stanford that works at the Doerr School of Sustainability.

He has done groundbreaking research in the study of geothermal energy and fracking as well. What was watching a video that Dr. Horne had been doing on trilemma between energy ecology and economy. And I think this app really sums up the place where humanity is sitting as it has vast energy usage. And every government and most people want expanding economic opportunities.

And there are enormous environmental costs with obtaining energy with all the current energy production methods. So I'm looking forward to talking with Professor Roland Horne, about which sources of energy yield the most energy for the economy with the least amount of adverse environmental impact, obviously, we're going to first focus on Geothermal energy is that Dr. Horns area of specialty.

I was noticing that, looking in Bill Gates his book, How to avoid a climate disaster. And in the in the book, there were only a few mentions of geothermal. And he thought it would play a very modest role in energy production going forward. I looked in John Doerr’s book.

And he, he also had mentioned geothermal in passing, but he didn't make it a focal point of his global action plan for solving our climate crisis. Now, in Greta tune Berg's book, the climate book, she briefly mentions geothermal saying it's a low carbon energy source. And 17% admits 17% As much as compared to fossil gas, but geothermal also produces other emissions like hydrogen sulfide and sulfur dioxide.

So welcome to the program. Dr. Horne, glad to have you on here and just want to kind of get your thoughts on where you think geothermal is role plays in, in solving our climate problems going forward? And are all these experts a little off base and kind of poo poo in geothermal?

Well, yeah, so thank you for inviting me. So I'm happy to be here to talk about geothermal. And you're completely right in the summary that you've just made that geothermal is kind of below a lot of people's radar. You know, I often described geothermal as the underground energy source. Because that's where it is physically plus, people don't seem to pay much attention to it. It is true that the current output of geothermal worldwide is relatively modest.

I mean, as of today, the geothermal output is equivalent to about three days of the oil production is currently being saved by the use of geothermal energy both in the form of electricity and direct heat, which is a relatively modest amount worldwide. However, one of the characteristics of the people you mentioned is that they live in places that don't use geothermal energy very much.

So the state of California where I am currently generates 6% of its electricity from geothermal sources. State of Nevada next to us produces 10% of their electricity from geothermal sources.

New Zealand produces about 22% of its electricity from geothermal sources. And the nation of Iceland produces two thirds of all of its primary energy from geothermal. And there are another there are several other examples too, like Philippines and Kenya and other places.

So in certain locations in the world, which are geologically advantageous. Geothermal is a very important source of energy. And a difference importantly from some of the other sources that you mentioned, like solar and wind, in that it doesn't have intermittency. Geothermal is sort of solid all of the time. It runs 24 hours a day, 365 days a year.

It's one of its important characteristics, and therefore it's a direct substitute in some circumstances for fossil fuels, where intermittent sources have to have some backup of some kind. And let me stress that I don't wish to claim that there's any kind of winner in this competition. I think the point, the principal point is that meeting climate change is going to require a complete portfolio of energy sources, of which geothermal is an important one because of its baseload characteristic.

I guess one question I have for you in terms of where you see it could be if it was more fully developed, what percentage of the PI could geothermal make up if we were to put a lot more in the way of resources in that direction?

And then I guess the question is, is that a wise move to for us to make given its its emissions of other things like hydrogen sulfide and sulfur dioxide.

But let me say, first of all, that is actually wrong. So there is hydrogen sulfide, and co2 in to some amount in geothermal resources. However, geothermal electricity has been inventoried, to have the lowest lifecycle carbon emission of any of the sources of electricity.

Actually, nuclear, wind, and geothermal are the three lowest. And they are 40 to 50 times less carbon emissions than for example, natural gas, and even less than coal. Sulfur dioxide, simply that's wrong. Sulfur dioxide is a very reactive gas, and it actually is not emitted from geothermal sources.

I guess we'll have to submit a correction to a climate book by Greta Thunberg, I just don't fight is present. However, you know, here in California, we have very stringent regulations on hydrogen sulfide emissions, and therefore the power plants have scrubbers that actually removed the hydrogen sulfide quite effectively.

So there's no actual emissions of it. And they turn it basically into elemental sulfur, which then gets distributed to the wineries around Napa Valley, which is where the principal geothermal source is the geysers here in California, and they use it for fertilizer.

So it's a useful byproduct, it doesn't doesn't leave the power plant in the form of hydrogen sulfide, has leaves it in the form of sulfur after the equipment has taken care of it.

So in terms of going back to the question of how do you think it could be developed? And obviously there's a certain question mark here in terms of, because you're drilling for geothermal heat, you can hit some dry holes, what's your best estimate as to what percentage of the world energy needs could geothermal meet if it was fully developed, or more fully developed?

Yeah. So I listed some countries which have large fractions that are characteristic of those countries that they geologically advantageous they have sort of suitable conditions for geothermal.

And I, I told you the percentage 6%, 10%, 22% ,60%. So what we want to achieve what the world would like to achieve could usefully achieve is to get up into those kinds of percentages, more broadly, and the places that are less geologically advantageous.

And then 2006, the US Department of Energy did a study looking to answer exactly the question you just asked, you know, what could we get nationwide? You know, how much of our energy could we get from geothermal. And they concluded that it was achievable to reach 6% nationwide, which is the percentage that we enjoy here in California.

So at least in the United States, making use of enhanced geothermal systems, that 2006 MIT report concluded that it was achievable nationwide to get to 6%.

Well, I guess the question is, what has what has been done in the last few years in particular, to increase that percentage? Has the Biden administration put any funds into pushing geothermal out?

They have indeed, so actually we now have have an increased research budget for geothermal in the United States, but actually has been increasing since that 2006 study actually. And the investment that US government has been making in geothermal has been to accelerate the development of Enhanced geothermal systems.

Okay, well, it's good to hear that we're studying it more. But I think we probably need to get into the implementation phase fairly quickly, though. Obviously, there are potential impacts for implementing any type of new energy source.

And we'll be back in just a minute to talk to Dr. Horne about those potential climate externalities, if you will, that are environmental issues that can result from doing something even as clean as geothermal. So stay tuned.

You're listening to A Climate Change. This is Matt Matern, your host, I've got Dr. Roland Horne on the program from Stanford, the Doerr School of Sustainability.

And Dr. Horne, right before the break, we were talking about what the Biden administration has done, and the US government encouraging the study of geothermal, what have they done regarding the implementation and getting actual wells being drilled and more energy being produced geothermal wise.

So the US government is not doing that directly. However, what they have attempted to do, I think was some success is to create an environment in which commercial entities can actually go ahead and do that.

So what we have seen in the last six, seven years or so even before 10 years, has been the creation of companies who are endeavoring to develop Enhanced geothermal systems, basically, as profit making ventures. So this is the industrial kind of ramp up of Enhanced geothermal systems.

There has been, of course, an active geothermal industry in the United States for probably 50 years for conventional geothermal systems. But the Enhanced geothermal systems, which is kind of the leading edge is now starting to see commercial entities entering the market as well.

So how would you define an enhanced geothermal activity? So earlier on, I talked about places that a geologically advantageous and those places which have hot rock close to the surface, usually associated with volcanism or not always as well as fractures that allow for hot water and steam to flow easily through those rocks, and carry the energy to the surface.

So those are the good places. And we have a lot of them here in California and Iceland and other places. However, there are other good but not as good places where the rock is hot, but not very permeable.

And that means that you don't have a mechanism to recover that heat, because you can't get water to go through the rocks. And in that circumstance, the process enhances the permeability of the rocks, using hydraulic fracturing, to allow for the fluids to pass through, and thereby create a commercial geothermal system where previously, it was sub commercial because the permeability was insufficient.

And I guess then the question is, what is the potential consequence of fracking, these rock structures, and the potential you know, downsides of doing that?

Well, let me make sure we don't confuse fracturing that we're accustomed to from oil and gas with fracturing and geothermal. So in geothermal, for example, we don't refer to it as fracking, it's referred to as hydro shearing and actually there is a fundamental mechanistic difference between the two.

That the kinds of rocks that are being fractured in geothermal are also rather different in that they are brittle volcanic rocks, compared to sedimentary rocks that have fractured in the land, gas. So in sedimentary formations that we see in shale oil and shale gas, they're producing mode one fractures, which are tensile fractures, basically splitting the rock apart.

Whereas in geothermal, the water which is injected to stimulate the reservoir basically causes the rocks in natural fractures to slide past each other in a sharing process, and in doing so enhances their permeability. So there's some significant differences between the processes. There are some, there are some downsides to doing it.

Even in geothermal, one of them is the potential for induced seismicity. So that's a that's a problem, which is the focus of research how to ameliorate induced seismicity in geothermal shearing.

But that's an issue that is needs to be addressed. I'm assuming that when you say induced seismicity, you're referring to earthquakes being caused by this process.

Alright, so that's quakes is kind of a strong term, when people think about earthquakes, they think about buildings falling down. But I mean, the earth beneath our feet is seismically active all the time, almost everywhere, in a small way that's not detectable by most people.

So geothermal reservoirs for that matter, any kind of underground activity causes tiny earthquakes all the time. But they're very small magnitude, you know, below one and two, which humans cannot detect. induced seismicity increases that level up to, you know, threes, and sometimes fours, which also, you know, not prominently detectable.

So, you can call them earthquakes, if you like, from the sort of layman's point of view, but they, they're kind of rumbling in the ground rather than buildings collapsing and falling down.

Right? Well as having lived in California for 30 plus years, I say, if it's not over five, it doesn't register, kind of on my personal scale, I don't notice it. So I'm kind of there with you in terms of the threes and fours kind of go beneath my radar, for sure.

But I guess in terms of what we should be concerned about is the long term effects. I know one of your students recently, did a study, fascinating study that I just read kind of the headlines of on subsurface microbial communities.

And it showed how these communities are, you know, this microbial communities are affected by the things that we do underground?

Should we be very concerned, so concerned that we don't do any more geothermal drilling or fracking? Or should we do it and do it cautiously?

I think from that specific point of view I don't think there's anything actually much to worry about the the temperature is that we are developing geothermal fields that are typically above 200 degrees centigrade. And at those kind of temperatures, there are no remaining microbes living they're all they can't live at that temperature.

So the study that we did was a low temperature, activity in a mine water, which was more or less at ambient temperature. It was a fascinating study, you're quite right, that showed how the fractures were created and how the water moved around based upon how the microbes differed from one place to another, but in an active geothermal reservoir, producing electricity or direct heat, the microbes would would not be living in that environment. So that's not an issue.

So, in terms of say, in from a non technical standpoint, if how many, you know say we really go full blast into geothermal and drill tons of wells, is there a possibility that we alter kind of the earth chemistry and structure beneath the beneath the surface that is going to be adversely affected or is there just so much energy down there that are pinpricks into the surface could never have much effect on that? The heat sources?

I think the latter so this is a question that people sometimes ask, you know, how are we going to cool the Earth down and turn it into a stone cold ball? And the answer is no. So that the amount of energy that actually comes out of the earth all of the time, that's being emitted by the molten core of the planet. I mean, is, is dozens of orders of magnitude greater than the total energy consumption of the human population of the planet.

So the amount of geothermal energy that is there, you know, is this hugely, hugely greater than, than what we're actually talking about, you know, that said, you know, locally, we could change the conditions that lower the temperature or move the direction of water flow in the vicinity of the of the geothermal operation.

I'm talking, you know, within a few kilometers, that might have some consequence. For example, you may have a hot spring that dries up or another hot spring that starts up as a consequence of the fluids moving in a different way than they did before.

Right, I was reading an article about Japan, and that they have a tremendous amount of geothermal potential, but they haven't really tapped into it very much, because the Onsen owners, which are the spa, owners of the hot springs, are always very concerned that hey, if they drill a well that it will affect their hot springs. So it's been kind of a political hot potato.

Yes, it is. Absolutely. So Japan has a very particular case, in that they have a tremendous geothermal resource, which is why there's so many hot springs there in the first place. And yet, they haven't gone very far with the geothermal development. For exactly the reason you explained, it's something of a of a sort of a misfit of opinions.

However, you know, the onset owners themselves drill wells, so they concerning of losing their water, but the direction that the Japanese geothermal community has taken has been more recently, not to fight the Onsen owners, but try and bring them on board. So what we see now in Japan is the so called deployment of micro binary.

So these are very, very small 200-300 kilowatt, geothermal power plants that can use the waste heat from the onset and, and provide electricity for three 300 bedroom hotel. And the onset owners kind of like that, because they get free electricity, and they're throwing the whole water away anyway, so they kind of coming along.

Well, that's it's good to hear that they're finding a way to tap that resource, because it does seems surprising given that Japan doesn't have a whole lot of fossil fuel resources that it would throw that one to the side, but politics makes for interesting decisions.

So you're listening to A Climate Change. This is Matt Matern, your host, and I am speaking to Dr. Roland Horne of Stanford. And he is working at the Doerr Schools of Sustainability. So we'll be right back in just one minute to talk to Dr. Horne some more.

You're listening to A Climate Change, this is Matt Matern, and we've got Dr. Roland Horne from Stanford on the program.

And Dr. Horne, where do you see in California, we've got a 6% of our electricity needs being met by geothermal. Do you see that increasing over the coming years? Or is that to stay in pretty stable?

One of the things that we are seeing worldwide is that communities of which geothermal are being used on generally increasing their geothermal production that's happening in California too.

So in spite of the fact that California was very early on in the process, a lot of our resources in the state were developed in the 70s and 80s. It didn't stop at that point.

So the development has kind of gone at a steady but slow pace. I think what we're now seeing though, is a different environment than we had 30-40 years ago, in which there is strong pursuit of renewable energy. And the intermittent sources have sort of run out of steam. In order to run out of momentum, I shouldn't say steam, in order…

In terms of how much faster they can increase, and they certainly will increase, because of the fact that we have to have a certain amount of power on the grid, there's only a certain fraction of it can be intermittent. So we need a certain fraction of stable power, we need a certain fraction of storage, that's an important new characteristic, the grids now, either pumped hydro or batteries or something else.

And therefore, that has increased the interest in renewable energies of all kinds, including geothermal. And so we have, you know, continuing geothermal development here in California, as well as in other places, most of those.

So where do you see it getting up to in terms of percentage of total California energy production? And what percentage would it need to be to kind of be the the supply source that was consistent during days when it's not sunny, or it's not windy.

So I think they're just all by itself will not be able to make that the cloudy, non windy day ever, you know, not be a problem and need something in addition to geothermal. Because I don't think we can ever get up to a point where geothermal could be making up 50%, for example of the grid.

However, if we look at our neighboring state of Nevada, they have achieved 10%. And actually, they're developing rather more aggressively than California is largely due to a very receptive legislature in Nevada, the vote of government seems to state government seems to be a big believer in geothermal.

But Nevada is a good test case, because they have a large number of relatively modest geothermal resources, for ones that we've seen in California are very large and very high quality resources. The fact that Nevada has gone so far ahead, taking advantage of relatively modest resources, that simply shows the path that could be followed in many places, including California have to you know, developing lower quality, smaller resources in a more widespread way.

So we have resources like that to in our state, and not largely developed currently, but they remain on the plate for development in the future. What other states in the US Do you see developing geothermal? Do you have it in, say, Arkansas, or Texas or Oklahoma big energy producing states?

Yes and no. So most of the current developing the current states that are producing geothermal electricity, at least, are in the west, towards the so called Pacific Ring of Fire. State of Hawaii also has geothermal development. We have resources in production in California, Nevada, Idaho, Utah, New Mexico.

So we tend to be in the West. So under the current environment of conventional geothermal resources, were sort of a Western driven industry and coming to Texas, Arkansas, Oklahoma, etc. Those places become attractive for geothermal developments, when we can implement Enhanced geothermal systems at a wider scale.

So drilling deeper, gives us those kinds of temperatures almost everywhere, not quite everywhere. But once we get down to those kind of depths, then enhancing the permeability is almost a requirement. So, once we have an Enhanced geothermal systems at commercial deployment, we can actually begin to move the geothermal boundary if you're like, towards the east.

So, how far is that away from being commercially adopted the enhanced production capabilities? Well, there are commercial Enhanced geothermal systems in operation in the world and some of them have been operating since you know 2007 2008 In largely in Europe, so they are rather small, they have been fostered by worthwhile regulation, feed in tariffs, for example, to help stimulate that industry to grow.

There's been a total of around 40 Enhanced geothermal systems built in the world mostly Blum research based, however, a number of them actually commercial. And there are, as I mentioned earlier, commercial companies now in the United States that are in the process of developing Enhanced geothermal systems, not on paper, they're drying wells, and they're intending to make money.

So what are those companies?

You want me to name them? Sure. The one that's furthest out front is a company called fervor about Israel, that fe, VO. And they are drilling wells currently now in in the western states. So they're looking kind of in the places where the geothermal resources are not very good, and enhance them as the title describes, and to get more out of them.

By doing that. Interestingly enough, they've got new technology that they're applying to geothermal, newly applying to geothermal, making use of horizontal wells with multistage fractures, which is widely deployed in shale gas. And shale oil, however, has not been deployed before in geothermal, because it's a lot more challenging to achieve.

Drilling those horizontal wells in very hard geothermal rocks, which is why people haven't done it before. But they have they've now drilled their first welfare in Nevada, and achieve some success in doing it. I believe so.

Okay, well, it's a it's great to hear that companies are, are breaking new ground sorry for the pun, and helping, you know, bring new energy sources to the fore that are have less carbon emissions than most everything else. So kudos to them, and kudos to you for helping push the needle in that direction.

So what's next? What, what can the government do? What can industry do? What can we do as, as consumers as investors, and what should we be doing here?

So one of the challenges that we have in moving this needle forward to wider deployment is the geological uncertainty. I've mentioned that a couple of times already.

A big difference between geothermal energy, and for example, wind and solar, is that you don't know what's under the ground, under your feet. So if you're going to drill a well, that may cost you five or $10 million, without really being sure what's down there.

Or whether I mean, even if you know that it may not be permeable, it may not be suitable for, for either shearing and stimulation. And you don't find that out until you drill it. So there's a large upfront capital costs in geothermal, which, although when it's in production, geothermal is actually a very cheap energy source.

To get there commercially, actually requires a lot of upfront capital investment. And that's, that's discourage people from going forward. What I think it really needs is investment at the scale of, you know, a billion dollars or so that was what was was listed in the 2006. Mit report, I referred to before and actually try it multiple times.

If you look at the shale oil and shale gas industry, it took them kind of 20 years, and literally hundreds of 1000s of wells to kind of get to the place they're in now, where they're drilling cheaply. They're just kind of rubber stamping out, well pads across the country, to get that scale of deployment in geothermal is going to need some significant investment.

So people can get up that learning curve and get to the point of doing it on an industrious, you know, a widespread industrial scale.

Certainly something that seems like our government would be well served and putting some of the 10s and hundreds of billions of dollars that are being allocated to address the climate issues that we are facing, and put that as seed capital because it can afford to take those kinds of risks where many investors don't want to be the first one in and potentially lose a few billion dollars. This would be a good investment to get our entire country in a energy independent and also a clean energy source.

So, you're listening to A Climate Change, this Matt Matern, your host ,and I am speaking with Dr. Roland Horne of Stanford and we will be right back to discuss the future of geothermal.

You're listening to A Climate Change, this is Matt Matern, and I've got Dr. Roland Horne of Stanford Doerr School of Sustainability on the show and we've been talking about geothermal.

And Dr. Horne, start to us a little bit about heat pumps, I know you're interested in teach a bit about it.

I know I was thinking about getting a heat pump from my house, which, and it's probably not one of the ones where you dig down into the earth to to get the the heat exchange, but I think it's more of an air exchange one. Tell us a little bit about your thoughts there.

Okay, so heat pumps is a is a wonderful technology to discuss. You know, a lot of people think that they don't quite know what a heat pump is, but everybody does. Because the refrigerator is a heat pump, it takes the heat which is inside the box, and it puts it out in your kitchen, it makes your food cold and it makes your kitchen warm.

And that technology is applicable over a wider range of temperatures than that. And an air conditioner is another form of a heat pump. That is in fact an air source heat pump. It takes the heat from you know inside of your room, and it puts it outside into the air.

So heat pumps are wonderful devices in that they have tremendous efficiency. Heat pumps can be used either for cooling or for heating, or both. So we talked about using it for heating, it's easiest one to understand.

If you have an electric heater in your room, that is consuming one kilowatt of electricity, it produces one kilowatt of heat into your room to warm it up a heat pumps however, you can use one kilowatt of electricity to drive the compressor of the heat pump.

And it produces four or five kilowatts of heat. And that's kind of seems like magic, but the extra four kilowatts of heat are extracted from the air outside and bought into your room. So it's free money, okay, you expand one kilowatt, and you get five kilowatts in exchange.

And that's, you know, a truly excellent technology. That's an air source heat pump. And although they work just fine, you also have to imagine what we're asking the heat pump to do. We're asking it to take heat from the outside, which is really cold in the wintertime, and bring it into the room.

So it's five times efficiency, but we can do it even better the ground source geothermal heat pump, the only difference really is that the place that it's taking the heat from is down under the ground, which is warmer in the wintertime than the air is.

So they have heat even higher efficiency than air source heat pumps. And therefore the even much more effective what's the the bang per buck there? What what does one kilowatt do in a ground source heat pump as compared to the four or five that you get from an air source heat pump, by air source heat pump, you know, in in a wintertime is probably you know, around three to four, whereas ground source can get up around five to six places there are places in the world Sweden being one Switzerland being another where it's simply legislated.

You know, you can't build a new building unless it's got the heat pumps, ground source heat pumps in it. And they have tremendously wide deployment Sweden remarkably, as one of the highest deployments of ground source heat pumps in the world. And it's not a country you would associate with volcanism are geothermal at all. And yet they have that that tremendous advantage, energy advantage that they gained from that deployment.

When I heard that the war in Ukraine, dramatically increase the use of heat pumps all across Europe that because the potential natural gas shortage that people were switching out natural gas systems to put in heat pumps, and that seemed to be make a dent at least in gas usage there?

Yes, absolutely. Plus, it also reduces the carbon emissions to, and then the only carbon emissions from a heat pump depend on the energy electrical energy that you put into driving the motor. And if you're sourcing that from renewable energy, then you have a carbon free source.

And in terms of in terms of kind of the environmental cost of building a heat pump, say if I don't use my, my heater that often am I really doing the the world a service by changing my, my gas heater to heat pump? If I'm, if I'm not using it, what's the what's the line at which you become, you know, becomes a smart move to to get a heat pump.

If you're using it all the time obviously becomes more a no brainer. But for those of us who may not use it, who live in Southern California and have temperate weather say, Yes, sir, you're absolutely right. It depends on where you live. So if you're not a big consumer of heat in your residential spaces, then there's not too much to gain. However, across the world, there are many places, you know, East Coast, for example, Minnesota, where they're using a tremendous amount of heat to stay warm in the winter. And they have a lot to gain by doing that.

First of all, because air source heat pumps are not as efficient when it's actually freezing outside of minus 20. They do much better with ground source heat pumps. And secondly, all of those places that might be burning gas or worse than that even fuel oil, then all of those carbon emissions then get avoided.

Well, that's a tremendous potential and for me, I mean, I look forward to the day when I have a solar array on my house and many other people do as well. So that so that we are not relying upon, you know, power sources that are fueled by coal or other non-renewable sources, the which would then make the heat pump, as you said, a very clean way to generate warmth and more or cold in the hot day too.

And it's quite right. So even even in Southern California, if you have solar panels on your roof, and a and a heat pump, which can both cool and heat to drive your air conditioning with your solar panels, then you're not taking any fossil fuel electricity off the grid. You're getting, you know, four to one bang for your buck in your your energy or cools that you're getting from your air conditioner.

And so you may not need much heat. But if it's getting hot in the summertime, then you can get that advantage. Yeah, and certainly we had a pretty hot summer, this last summer and we had a pretty cool winter this winter. So you know, there is some use for heat pump even for us weather wimps down here in Southern California.

So where where do you see the the world turning in terms of geothermal in the next decades? Do you see great progress being made? And and where do you see the next breakthroughs?

So the enhanced geothermal systems as we talked about before, I'm moving ahead quite rapidly. Now. The deployment of heat pumps is also increasing a lot. You know, heat pumps, more than a million installations of heat pumps in the US mostly on the east coast.

But that's expanding. And I think the overall kind of mix of geothermal into the portfolio that we have in the US and in other places, is being enhanced significantly as we go forward. So backfilling countries that are kind of maxing out on wind and solar in the current state, where storage is still quite expensive, have a lot to gain by moving forward with geothermal.

And we're seeing that happen in a lot of places. Yeah, I hadn't really thought about before, but those in ground heat pumps are actually kind of a geothermal type of energy as well.

And I guess, to me, it seems from a public policy standpoint that the government should be encouraging people to buy those because it makes us more energy independent. as well as is environmentally friendly. So it's a it's such an easy win. We should be encouraging it at every level.

We should absolutely.

But I'm not seeing as much adoption. And I guess the other thing is the manufacturing of heat pumps. And I had read somewhere that there was some question as to shortages, given the tremendous amount of buying that was being done in Europe post.

You know, Russian invasion of Ukraine, are there any kind of supply chain issues here in the US about purchasing heat pumps, I actually don't know that it's likely to be driven by the same forces. But one of the things that we're lacking a little bit in the United States at the moment is plumbers.

Okay, so somebody has to install those heat pumps and has to be someone who has the expertise and experience. And there are plenty of people like that already in the US, but not as many as know how to install a gas furnace.

So we have to move the needle towards a, you know, a fleet of plumbers, who are familiar and experienced in installing ground source heat pumps, and ended up preferring to do that, compared to installing gas furnaces.

Oh, it's always kind of interesting and intriguing how little things make big changes and the need for plumbers. Though an ancient profession is something that we need in our modern world and think it was said that plumbers probably saved more human lives than doctors through just better sanitation.

So plumbers may save us through environmental you know, sanitation as well. I haven't seen cleaner power sources. So look at that.

We've come full circle. Well, you've been listening to A Climate Change. My guest Dr. Roland Horne of Stanford, teaches at the Doerr School of Sustainability. Thank you for being on the show. It's been great having you and love to stay in touch. Follow your research as you go forward.

Thank you.

Turn into A Climate Change on our website. You can find it at www.climatechange.com or on our social channels. Thanks for listening.