 Typically these courses this conference is for kind of incoming graduate students. I think that is largely the case now although because it's virtual we also have the ability to include other folks and so they don't want to just chime in where you know what kind of degree program you're entering into. Yeah I can start. I'm an incoming graduate student. My field study is physics and I'm currently in at home in Pasadena, California. Very good. Well not too far when when the day comes you can come here. Okay so I'm in my name is Greg. I'm in the Joint MBA, MS in Environment and Resources and just moved into campus a couple days ago so calling in from Escondida Village. I'm Haley and I'm a first-year PhD student in electrical engineering. I'm currently at home in Albuquerque, New Mexico but I hope to move to Stanford soon maybe in the quarter. I'm Luke. I'm a first-year master's student in the Arrow Aster department and I'm currently crashing with a friend of Berkeley until I move in on Friday. I'm Richard Randall. I'm a first-year PhD student in mechanical engineering and I moved down to Stanford two days ago and I still have no furniture so I'm sitting on the floor. My name is Josh. I'll be a master's student in the Civil and Environmental Engineering Department focusing on atmosphere and energy and I'll be moving to near campus uh wait next week and I'm excited to get started. I I guess I'll go next. Hey my name is Ali. I am I'm actually in a interdisciplinary humanities program called Modern Thought and Literature and know very little about energy but I thought this would be a good experience and it seems to be like a very defining conflict of our time. So I'm I actually just moved in yesterday and still it's still a little chaotic here and unpacking but I'm I'm talking to you live from Palo Alto and else. Wonderful. Well welcome. If it's any consolation my background is in English so I I've warmed to the sound of Modern Thought and Literature but it's it's great. We love getting a sort of diverse perspectives across you know the very technical to the more kind of cultural and so forth. I can go next. Kind of to break the trend a little bit. I'm a rising software and earth systems major. Well the nice thing is if you make some friends this week then you know if you're ever considering future directions to take then you can have a bunch of friends to ask what what it's like and so yeah I guess I will without further ado just introduce our actual speaker not me who's taking up all the airtime right now. So Roland Horn you can see somewhere on your screen hopefully and we'll be sharing his screen shortly but he's a the Thomas Davies Barrow Professor of Earth Sciences at Stanford University and a senior fellow at the Precourt Institute for Energy which is the institute running this event that you're part of. He's best known for his work in well test interpretation and I've now lost my introduction sorry. Production optimization and analysis of fractured reservoirs. He's an honorary member of the Society of Petroleum Engineers and a member of the US National Academy of Engineering. He's also served on the International Geothermal Association Board and was its president from 2010 to 2013 and there's a whole list of awards that I will not run through but we're very honored and pleased to have him here to share his expertise with all of us thank you very much. Very good so thank you Sarah and welcome good morning everybody congratulations on waking up so early. You should be able to see my screen currently is that what you see good all right. So I'm going to talk about geothermal energy which has actually been the focus of my career for a very long time and for those of you in the western states you may or may not be familiar with geothermal energy in spite of the fact it actually produces a significant fraction of our energy here in California and actually also Nevada and a couple of other states as well. I'm going to talk mostly today about geothermal energy because in fact surprisingly a lot of people don't quite understand what it is we all know what solar and wind is about but geothermal is kind of underground as an energy source underground because that's where it is and underground because a lot of people never heard of it. I'm sure most of you have but perhaps are not as familiar with it as I hope you will be in a few minutes. So this is what I plan to talk about today where we are how we use geothermal energy and I'll finish up saying what we do with geothermal energy at Stanford. So during your lifetime starting in about 2005 15 years ago tremendous increase in renewable energies not only in the United States which is what this graph shows but around the world but I showed this graph in particular it's now 10 years old already but to point out the fact that the old style of renewable energy which was generally hydropower has actually been declining in the United States as well as in quite a number of other places. There's some good reasons for that which we'll talk about during today because I want to put geothermal in the context of renewable energy in general. In spite of the growth that we've seen in renewable energy what much further than we saw until 2010 renewable energies come in different flavors and you see in this particular graph a distinction between most of the renewable sources that we use today and nowadays principally wind and solar and geothermal and biomass the principle being that geothermal and biomass are not intermittent they can work 24-7 and therefore they have a place to fill in a portfolio of energy which actually can replace some of the fossil fuel generation that we hope to get rid of. In addition to that geothermal is in terms of its life cycle a very low carbon source effect is one of the lowest only slightly behind wind. You might ask why does solar PV have a carbon footprint at all because it doesn't produce any carbon but actually quite a lot of carbon produced in the and implementation of solar PVs and geothermal is growing. We have every five years a world geothermal congress and one of the functions of that congress is to actually make an inventory of the world's geothermal resources. We were supposed to have one in 2020 but it's postponed until 2021 so these are the figures from 2015 and you can see the growth of geothermal energy production worldwide now both in terms of megawatts installed as well as gigawatt hours actually generated which is perhaps a more definitive number and the projection in 2015 was that we would be at around 20 gigawatts by 2020 and if we look at a more recent picture you can see worldwide the growth of geothermal energy in the various countries of the world and in particular there are some which are growing at a tremendous rate so I pointed out the more significant ones there Indonesia Turkey and up the top there in Kenya have more than doubled in a case of Turkey they went from around 15 megawatts to more than 1000 megawatts over the past 10 years so they have a very very significant rate of growth these these this set of graphs here is in actually numerical order the United States there at the bottom see is kind of stable but actually we are number one in the world in terms of production of geothermal electricity second is Indonesia just recently overtook the Philippines and then just putting the graph the same graph in a slightly different context you can see the rate of growth in Kenya Turkey and Indonesia and importantly that growth is not just from the last 10 years but is continuing now so you can see the amounts in orange have been added over the the one year in which this total was taken now let's come a bit closer to home I'm going to show you three or four snapshots of electricity generation in the western states and importantly California so in 2010 10 years ago geothermal energy this is all production of electricity in California 28 percent or 30 percent almost was renewable one of the things that we need to take account of is whether or not to include hydro hydro is clearly a renewable energy source but legislatively hydroelectric power is not counted as renewable and the reasons for that hidden in politics but anyway I'll include it here for a moment but anyway six percent of all electricity in the state of California was generated from geothermal and importantly also two six percent of the electricity in the state of Nevada is also was also generated from geothermal in 2010 and you can see at that time 10 years ago geothermal exceeded wind and solar by a substantial fraction and was only in fact exceeded by hydro if we've moved forward into let me just back up and say hydro let me ask you to remember this number 2010 hydroelectric power generated 33,000 gigawatt hours over the course of the year to remember that number 33,000 moved forward to 2013 you can see geothermal still generating 12,000 and you can see by this time wind actually had crept up and exceeded geothermal in 2013 take a look at hydro hydro dropped from 23 that from 33,000 to 23,000 and those of you who live in California will know why we have had long periods of drought which lasts sometimes for multiple years and that's significant to the conversation we're having because although wind and solar are cyclic on a daily basis some goes down every day hydro is cyclic also in the state of California it's on a sort of cycle of about five to seven years it goes up and down as well jump forward to 2015 geothermal still six percent of generation in California you'll notice now though that wind has stayed about the same and solar moved to the front so the big expansion of renewable energy in the state of California solar thermal and solar PV this by the way is not rooftop solar this is a utility scale solar and you'll also notice that about half of the electricity generated California comes from natural gas and then this is the last the most recent numbers I have to show you I should point out here hydro there in 2015 13,000 gigawatts 33 2313 so running out of water in a hurry in California 2017 it rained again so hydro went back up to 43 so that shows how variable that is geothermal still at six percent in California and most importantly nine percent in the state of Nevada and that's a very significant number not only in terms of its growth but because Nevada in general has relatively modest quality resources so here in California we're bled we're we're blessed with high temperature resources of the order 200 250 degrees centigrade Nevada has rather modest the temperature resources around 140 150 degrees centigrade so the fact that they're able to grow actually is significant in terms of the technological advance that it represents you'll also see to the significant part now played at least in 2017 by solar when does remained about the same since 2013 and is still about the same as geothermal so that's sort of looking at the yearly scale let's take a look at the daily scale this is one particular day in the life of California and if you've never encountered this website I highly recommend it to you California ISO.com and the California ISO is a people who dispatch the power around the state of California and at any particular moment you can see how much electricity is being generated and consumed you can also see where all of that energy is actually sourced from so this is about lunchtime around this time of year last year or the year before you can see on the right side the renewable sources and you'll notice on the left side 44 percent of the electricity that day in California was being generated from renewable resources not including large hydro and if we look at that same day actually this is a previous day we can see nonetheless how it changes over the course of the day so in particular the salt the sun is pretty reliable comes up and goes down much the same time of the day and except in weather like this it shines strongly in the middle of the day so an interesting aspect of wind and solar in the state of California which is true in quite many places is that the wind is more prominently blowing at night and of course the sun shines during the day so wind and solar actually have a symbiotic kind of relationship that fills in the gaps of the day geothermal you notice rather boringly stays lock steady the whole of the day and for that's actually one of the natures of geothermal power plants it isn't easy to switch a geothermal power plant on and off the same is true of nuclear they work best if they're running all of the time and that's the way that you see them running it's not evident in this particular graph but actually over the past five to seven years or so we have so much solar in the state of California that the geothermal operators have actually began to regulate their production just a little bit it's not easy to do technically they're not designed to be operated that way but they are now tending to throttle the geothermal power plants during the middle of the day because actually they get paid more if they have some kind of throttling capacity because it helps the ISO to control the grid and you'll notice that particular day state of California was generating 45 percent of its electricity from renewables not including hydro so you've seen this graph I'm sure before also it's the so-called duck curve which shows the 24 hours of the day from midnight back to midnight and what's classified here as the net demand is the electricity that the California ISO has to find outside of wind and solar and in the middle of the day it's a very small amount the modest amount this graph doesn't go to zero but most importantly during the afternoon from about four o'clock up to about seven o'clock the California ISO has to magically find a very very large amount of electricity generation about 13 gigawatts on that particular day so that is a very significant logistic and technical challenge for our electricity market and it has changed everything in the way that the electricity market now works in the last 10 years so although geothermal and nuclear used to be so proud that we were such a strong base load power source it seems like a good thing that's not intermittent however that's no longer true base load power is kind of a nuisance because you can't get rid of it in the middle of the day and nuclear and geothermal can't be shut off and that means they have to do a lot of manipulation of distribution in the middle of the day and most importantly neither nuclear nor geothermal are so called fast ramping you can't switch on 13 gigawatts of power if your sources are solar and geothermal that electricity principally comes from natural gas it's one of the reasons for the prominence of natural gas is that we have to have these fast ramping plants in order to be dispatchable in the afternoon and those of you who happen to be interested in study and research in energy finding renewable sources of fast ramping power or storage are two of the prominent research questions which we face today now in order to meet some of those difficulties in the grid what we are seeing is an increasing introduction of battery storage into the electrical grid and i don't know what our installation is today but it's of orders of hundreds of megawatts in the state of california and you might imagine that you know we charge the batteries in the daytime with our solar energy and we discharge them at night when the sun is not shining that however at the moment at least is not true you can see in this graph how the batteries are used or at least on that particular day how they were used in order to regulate the electrical demand of the state and importantly what you see is that the battery storage was charging and discharging sort of almost continuously during the day on and off at very very high frequency they're on for 10 minutes and off for 30 minutes things like that typically nowadays at the moment the battery storage that is implemented on utility scale is principally made up of kind of so-called salvage batteries if you ever wonder what happens to tesla batteries when people wear them out this is where they go they go into big boxes in attached to the grid and they're not particularly good for electric cars because they don't hold a charge very well anymore however they can hold a charge for 30 minutes so actually probably several hours and be useful to regulate the grid in the way that you see and this is a very significant growth area in both technology and commercial implementation battery storage and actually other kinds of storage too now the challenge for us in geothermal i'm going to talk about geothermal now because that's what you're here to hear about is to how to fit into a dispatchable power market and we're beginning to see now in the world the implementation of dispatchable geothermal power and here is an example actually from hawaii the puna geothermal plant hawaii grid of course is very particular because the islands are isolated from each other each of them is a so-called island grid and therefore it isn't easy to move electricity from place to place each individual power plant has to be dispatchable because they can't throw power away so puna plant this one particular plant is rather famous in the geothermal world community for having the ability to regulate itself the way it actually does that by the way is kind of low tech they more or less have a bypass from the past power plant so they can actually take the hot water from the ground instead of taking it through the plant they just put it back in the ground again it isn't wasted because of course that hot water is still there in the ground to use later on my original home country in new zealand has a even more significant fraction of geothermal energy as well as renewable power new zealand is more than 80 percent electricity from geothermal from renewable sources and around 20 percent from geothermal island is another famous geothermal country and importantly this is not just electricity now this is all primary energy including transportation cars and trucks and importantly in iceland also boats fishing boats and what you can see there is that two-thirds of the primary energy of the nation of iceland comes from geothermal they also have a decent amount of hydro as well and let me switch to japan some of the other countries japan lives around the pacific so-called ring of fire it's also a geothermal nation like the philippines new zealand and indonesia and california too and you can see here that japan has had a history very similar to california in terms of renewable energy from wind and solar it turns out solar is a more suitable resource in japan because the wind is very variable it doesn't blow sort of continuously the way it tends to do in california but that japan has geothermal too and in fact geothermal was one of japan was one of the earliest nations to make use of geothermal in the 1970s as was california too and despite the fact that you see there cal, geothermal is a very small fraction of the renewable energy in japan there are particular places where geothermal is very important you see them actually listed there that those four prefectures the red bars represent the fraction or the piece of their geothermal energy which piece of their renewable energy which comes from geothermal um technically from the point of view of research we are seeing innovation in the geothermal industry in in the form of understanding of the subsurface first of all that's the geological part of the of the technology that's really the part that i work in as well as in the surface technology the um decided power plants and surface equipment so this particular plant that i have a photo of here which is in new zealand represents a kind of a modern implementation of the many plants that we have all around the world in in in terms of its the complexity of its cycle so this is known what is known as a combined cycle plant and what you can see here in the in the center of the picture middle here that building square building um contains a steam turbine and unusually it has a much higher pressure than geothermal turbines normally do principally because the the inlet pressure of the turbine is governed by the resource itself which are generally quite modest in temperature i mentioned before many of the the resources in the state of california have a resource temperature of around 250 degrees centigrade now that sounds hot however if you compare that to a a fossil fueled steam plant or a nuclear steam plant which typically have supercritical steam cycles they have steam temperatures of which can be 600 or 800 degrees centigrade so the consequence of that is that geothermal turbines tend to be very big first of all which makes them expensive in terms of steel because the volume of the steam is much greater at lower pressure and temperature and secondly their efficiency is is less because of the lower pressure it doesn't matter so much because the fuel of course is basically free it comes out of the ground nonetheless that's that low pressure is one of their characteristics this particular plant is built on a on a field which is called rotocawa which has a very high temperatures around 300 degrees centigrade and therefore high pressure so that they elevated the pressure of the turbine to around 25 atmospheres typical geothermal turbines are five to eight atmosphere pressure something like that but what's interesting and important about this combined cycle plant is that the exhaust from the turbine runs into a binary plant so all of these kind of fans that you see in the background actually are the cooling towers for the binary plants the binary plants themselves are actually in the front these small boxes they're out in the open a binary plant is like a heat pump basically it has a closed cycle which which has turbines typically of either pentane or isobutane they heat the pentane to make a vapor the pentane vapor goes through the pentane turbine and then is cooled in those air draft cooling towers they don't discharge any water to the atmosphere the way the steam plant does because of course they're working with pentane but that combined cycle taking the exhaust from the steam turbine through the binary plant allows that plant to have a very high efficiency and we classify the efficiency in terms of the steam consumption per kilowatt hour generator so rotocawa has a steam consumption of about five kilograms per kilowatt hour and that compares to eight to ten kilograms per kilowatt hour on some of the older plants that we have in California so it's almost twice as efficient I might mention I don't have a picture to show you but the the binary plant that you see there is actually I do have a picture it's coming up here this one this is a binary plant in Nevada doesn't have it's not a combined cycle it doesn't have a steam plant attached to it at all binary plants are pervasive in the state of Nevada because the resource temperature is so much lower the steam plant basically would not be effective or it'd be too expensive so what's interesting about this particular plant this is a place called still water is it's a it's a hybrid of a different kind in this case they've hybridized solar with geothermal and one of the characteristics of a binary plant because it uses air cooled condensers for the power station it's least effective in the middle of the afternoon three or four o'clock when it's hot and the sun is shining so the geothermal plant actually has its lowest output in the late afternoon and that of course is the time of the day when a solar plant has its highest output so given that they occupy a certain amount of land for the geothermal plant they in this case you can see have added solar pvs the two plants are not connected except electrically so they kind of backfill their output in the afternoon one when the demand is highest and two when the geothermal plant's output is at its lowest and this particular plant is interesting in a second way is that they do in fact have a genuine hybrid where they've added solar thermal where the parabolic troughs are actually heating the binary fluid and actually they're adding kilojoules into the binary plant itself so in that case they're actually a combined cycle solar and solar thermal and geothermal so in i will finish in a few minutes let me talk about a different aspect of geothermal energy which is direct use and there are many that you see listed there if we look at the energy use of the united states and most importantly the temperature at which it is used you can see there the tallest bar most of the thermal energy that we use for space heating water heating air conditioning etc is actually at modest temperature 40 to 50 degrees centigrade currently most of the houses in the state of california that need heating space heating and water heating do it with natural gas which certainly for one has a carbon footprint and number two thermodynamically makes no sense whatsoever natural gas flame around a thousand degrees centigrade why make a thousand degree flame to heat your house to 20 degrees centigrade in the winter it's a very takes a high quality resource for a low quality requirement but 40 to 60 degrees centigrade is in fact the temperature that many geothermal resources are available we have geothermal hot water at 40 degrees 60 centigrade almost everywhere if you drill down to a modest depth if we look at direct uses of geothermal energy we can see that they are very widely dispersed in many applications and furthermore they're increasing this graph rather strangely goes from right to left but you can see the rate of increases of all of those different applications most importantly the one on the left number one geothermal heat pumps which are used pervasively all around the world even because they don't require high temperatures and if we look at the countries of the world which make use of direct geothermal heat uh United States is also prominent on that list as well although we actually fall behind China and you can see here some kind of non-traditional non-volcanic regions like Norway and Germany which have a great deal and Sweden have a great many applications of geothermal heat pumps and I don't imagine you have the opportunity to see this right now the the energy week that you're part of normally takes a tour of SESI which is our energy system on campus which has three of the world's largest heat pumps this is one of them that you see right there and what SESI does is to take waste heat from returning from buildings and switch it from the returning cold water supply back to the hot water supply and that allows us to have one of the most one of the most efficient heating and ventilation systems in the world the interesting thing about SESI I'm sure you'll hear lectures about SESI even if you don't get to see it this week is that over the course of the year the heating requirement and the cooling requirement of the campus in terms of gigawatt hours is about the same the area above the blue area and the red areas are more or less equal in size so we are recycling kilojoules from heat to cool and back the other way the problem of course is that during the course of the year in the summertime we have too much heat so we have to dissipate that part which is in the bright blue in the summer in cooling towers that of course is an intentional a cooling tower is a device constructed with a specific purpose of wasting energy just throws it into the atmosphere and the bright red part in the winter time is the excess heating requirement which we have to fulfill for the campus which at the moment is met with natural gas so phase two of SESI not yet implemented is to take away the blue and the red and actually implement a geothermal ground source system you can see a map of the campus there and the plan is to install 26 wells which take the water out from the ground run it through SESI in the summertime for cooling put it back in the ground warmer than it came out and then because of the thermal capacity of the ground we can recover that that heat in the winter time and use it in place of natural gas and if if or when that system is implemented we'd actually be able to have a carbon-free heating and ventilation system for the campus we won't have to use the cooling towers in the summertime the way we do now and here is a geothermal well if you like to see one this is Panama Street not far from the building that you would be in normally for energy week this is one of three test wells that was drilled on campus a few years ago in design of that system okay so let me just draw this to a close looking at the overall geothermal world both in electrical use and direct use of geothermal energy in terms of the avoided oil consumption if we specified in barrels of oil equivalent at 239 million barrels of oil and the avoidance of 32 million tons of CO2 it's about three days of the current world's oil consumption not a massive amount but anyway an amount which makes a significant difference so what you've seen here a big expansion of geothermal energy in the last 10 years although it's been going for more than 50 a lot of new technologies have been implemented over that time lower resource states like Nevada are now being recovered because of those advances in technology and in the future we have a technology known as EGS or enhanced geothermal systems in which the reservoir is actually stimulated to make resources in places which don't currently have them all these don't have have the the quality of resource which we currently need to generate electricity or heat so let me close with this picture of the geothermal research group at Stanford geothermal program you can see some of our members here is a research program in the energy resources engineering department where I live it's existed for since 1970 more or less so a long period of time and we typically have six to eight students researching in that program the general focus of the research of the ph2 students and master students in that program are associated with the subsurface we're interested in how water and steam flow in fractured rocks most geothermal systems are found in volcanics and therefore they differ rather in rather interesting ways from oil and gas recovery which are typically found in sedimentary rocks so here's some other pictures of our group that was actually the world geothermal congress in 2015 so that let me stop and invite your questions this picture by the way is at the geysers geothermal field here in california it's the world's largest geothermal field and it generates about four percent of california's electricity by itself thank you for the lecture i really appreciate it i'm dying to know why is it that we as a society have shifted towards solar and wind which is an intermittent resource and is the same economically speaking as geothermal and i'm expecting a huge effort to change the grid in order to compensate that which seems like a huge amount of effort why are we doing that rather than just relying on naturally non-intermittent sources such as geothermal especially geothermal because it doesn't have many of the negative consequences that nuclear imposes yeah yeah so that's a good question so let me go back to the beginning of your question one of the unfortunate facts about geothermal is it is more expensive than wind and solar and it and it is so for a number of reasons i'll come to in a moment ballpark figures geothermal in california is six to eight cents per kilowatt hour whereas wind and solar are now down almost two to four cents a kilowatt hour in some circumstances so the proliferation of cheap solar pv panels over the last 10 years is largely responsible for the huge expansion that you see in terms of solar you're you're right that the intermedancy is an issue and actually it's an issue not only for the grid but it's also now an issue for the solar generators as well because even if even if you implement you know a 50 megawatt solar plant if you can't sell your 50 megawatts because the grid is saturated with solar and you're you're basically you're doubling your cost if you're going to sell half of it you're doubling the cost of what you paid for as opposed to running it all of the time another issue with wind and solar is simply the time that it takes to actually deploy a project so you can order up you know 10 megawatts of solar panels from china and you can buy yourself a bit of land close to an electrical hookup and you can probably build a solar plant in a couple of years including the licensing everything else the difficulty with geothermal which in fact is one of the reasons for the focus of the research we do at sanford is the geological uncertainty it's deep below the ground it's you know 5000 to 10 000 feet down and understanding exactly what is there is not so easy and it's also expensive we have geoscientific methods for doing exploration for geothermal but in the end we we have to drill wells and they cost a lot of money about 10 million dollars each so you drill a well 10 million dollars maybe there is a suitable geothermal resource there or maybe there isn't and that risk cost is what eventually translates into the ultimate cost of the electricity there are places Philippines for example where the geothermal energy is much less expensive than in California mostly because of the quality of their resources and the cost of deployment and construction of a power station but you're right if we could improve our ability to assess the underground resource we could actually deploy geothermal to a much larger extent and one of the hopes for geothermal is EGS enhanced geothermal systems where we would imagine that we don't have to have such perfect geological conditions if we drill and don't find a reservoir we make our own reservoir by fracturing the rock as long as it's hot we're still good and that's the current direction of geothermal research actually us-wide enhanced geothermal systems so sorry as a quick as a quick follow-up then and then I want to let other people ask questions as a quick follow-up so in terms of the future direction of geothermal would you say because I wrote it down your quote was baseload power is now in nuisance so would you say that even if geothermal technology improves to the point where it is now less expensive in solar and wind do you think by that point the grid would have shifted to a point where baseload power is no longer desired and it's completely restructured I don't think we're ever going to go back so I think the grid is going to be the way it is now at least for the foreseeable future and that's why storage is so important it's interesting to me looking at the history of the grid in california when they built diablo canyon is that its name the nuclear plant second nuclear plant in california when they built that in the 1970s it's a 1000 megawatt plant they also built a pumped storage system pumping water uphill because they knew that having a thousand megawatts so they couldn't switch off there's also a second thousand at san anofri nuclear plant which is now shut down because they had that 2000 megawatts of the load supply that they couldn't get rid of they installed pumped storage at that time specifically to fill that issue of the baseload power so storage has always been an important part of regulating the grid when you have large baseload resources that you can't you can't regulate easily so that's why I said before that storage I think is the future growth area for electrical grids california and I think everywhere probably batteries but perhaps something else all of you indeed come up with other creative ideas we do have we continue to have pumped storage in california too as well as in other places okay we have just a couple minutes left but luke has had his hand raised so do you want to throw your question out I think that'll be our last thing sure thank you for the talk dr horn um so coming from an aerospace background I mainly find geothermal energy energy interesting from its potential application to future settlements on future human settlements on extraterrestrial environments like mars and I was reading particularly in Forbes someone's someone estimated that 20 years after humans first arrive on mars we could have geothermal energy plants set up and I was wondering if with your experience and in your opinion that was actually a feasible estimate or if that was extremely over overzealous and over enthusiastic um I don't know what the geological conditions are like on mars that the kind of geothermal resources like the one that you see in this picture um may or may not exist on mars it requires organism and high temperature heat however low temperature geothermal resources almost certainly exist on mars in that you know because mars has a day night cycle the air and the ground will be at different temperatures and anytime you have a different temperature you can move energy from one to the other and capture some of it in the process that's that's the way that sassy works with the heat pumps so by by drilling modestly wells of modest depth into the subsurface of mars you could move heat from the atmosphere to the subsurface um whether or not there's sufficient water to do that not that water has to be the the the carrier mechanism but water is the cheapest and easiest at least on earth you need some sort of some sort of carrier fluid to transport the energy around um but it's certainly a feasible technology