Episode 25: Losing Steam: Carleton College’s Energy Transition - Transcript
Dave Karlsgodt 0:00
Welcome to the campus energy and sustainability podcast. In each episode, we'll talk with leading campus professionals, thought leaders, engineers and innovators addressing the unique challenges and opportunities facing higher ed and corporate campuses. Our discussions will range from energy conservation and efficiency to planning and finance, from building science to social science, from energy systems to food systems. We hope you're ready to learn, share and ultimately accelerate your institution towards solutions. I'm your host, Dave Karlsgodt, I'm a principal at Fovea, an energy, carbon and business planning firm.
Martha Larson 0:33
We spend lengthy periods of time below zero, you know, we'll sit there at 20 below for a few days at a time. So this concept of geothermal and 120 degrees Fahrenheit hot water, you know, it really was tested and talked about as far as can it handle the Minnesota winter and we proved to ourselves and our leadership and even our engineers probably proved to themselves that this was going to work.
Dave Karlsgodt 0:55
Well, it's good to be back as your podcast host again, our last three episodes featured interviews from our guest hosts, including our summer interns. We have some more interesting projects in the works from Kaia and Sarah coming up over the next few weeks and months. In this episode you'll hear an interview I recorded at the 2019 AASHE conference in Spokane, Washington. My guest is Martha Larson, manager of campus energy and sustainability at Carleton College in Northfield, Minnesota. One editorial comment, we recorded this interview in the halls of the convention center, so you're going to hear a little bit of background noise. Our conversation focused on Carleton's ongoing transformation of their campus heating and cooling system. Carleton is in the process of switching from a traditional high pressure steam system to a low temperature hot water system using ground source heating and cooling as well as heat recovery technology. In my experience, the average sustainability professional does not get all that excited about steam pipes, chillers and heat exchangers when it comes to renewable energy when solar and battery seem to get all the leading roles. I'm hoping this interview will start to change that perspective, or perhaps expand the cast of renewable energy characters at play. Martha is an experienced engineer, a thoughtful systems thinker and a truly gifted communicator. She and her colleagues at Carleton are leading the charge on the types of systematic transformational change, we need to end our reliance on fossil fuels and create a carbon neutral society that can work for everyone. Martha also is able to connect the dots on how this project aligns with Carleton's institutional mission, supporting a better working environment for their facility staff, and how she and her team were able to make the business case for such an ambitious transformation. I hope you enjoy this October 22 2019 interview with Martha Larson. Well, I'm at the AASHE conference. I'm here with Martha Larson. And we're overlooking the Spokane River at the conference and we are going to talk about steam to hot water geo exchange at Carleton College. So Martha, it's great to be here.
Martha Larson 2:50
Thanks very much, Dave. I'm happy to be here. Thanks for the opportunity.
Dave Karlsgodt 2:54
All right. So can you just start out with just a basic introduction of yourself, your institution, and we'll go from there.
Martha Larson 2:59
Yes. My name is Martha Larson. I'm the manager of campus energy and sustainability at Carleton College. And I am the first person to hold that position. It was created in 2010. I came to it from a background in a degree in mechanical engineering, but really my career background was in project management. So wanting to move into environmental fields, it was a good match to come to Carlton and be part of the facilities department as a project manager, but also have the responsibility to build a sustainability program and an energy management program. So I now work there, there's an office of two I have a fabulous colleague Alex Miller, who's our program coordinator, Carleton set a goal of being carbon neutral by 2050. And they did that when they signed the college and university presidents Climate Commitment in 2007 and 2011. We did publish a Climate Action Plan and so that really cemented the goal and also did some quantified calculations on different strategies that might help us reduce our carbon footprint. So over the last nine years, we've executed some of the Some of them we've explored and dismissed and then others like the project we're talking about today. We're not even really defined in our minds at the time that we published the plan. So it's very exciting to be at a place where we've now implemented quite a few strategies.
Dave Karlsgodt 4:14
Yeah, it's not 10 years in the future. It's 10 years in the past now that
Martha Larson 4:17
it is it's hard to believe, but it's now 10 years in the past.
Dave Karlsgodt 4:20
Very nice. Well, tell me just a couple of stats on Carleton. How big is it? Where is it? It's an I guess,
Martha Larson 4:26
Carleton college is in Northfield, Minnesota, 45 minutes south of Minneapolis, St. Paul, it was founded in 1866. So it's been around for a while. And it's a small liberal arts institution focused on high quality of teaching, high quality of education. And we have about 2000 students about 2 million square feet. And most of those students are housed on campus. So we consider ourselves a residential campus and then that of course, affects our energy footprint as well.
Dave Karlsgodt 4:51
Okay, great. Well, let's talk about this project. What I was there in September, I was able to tour the power plant and get a little Bit of a history on how you guys have switched from more of a traditional steam system to deal exchange heat recovery system. So tell me a little bit about what's there. And then let's back into how you got to that system.
Martha Larson 5:11
Right. So as of today, we just completed phase one, which is we drilled three geothermal bore fields to vertical one horizontal. Those bores are about 510 to 520 feet deep, so they're quite deep. And as part of the phase one, we install the heat pump chiller that works off of the geoexchange. We also retrofitted our East Campus buildings and our East Campus distribution piping. So the piping we pulled out the steam we put in hot water piping, and in the buildings we increase the surface area of the radiation and change out some air handling unit coils and other devices to run those buildings on 120 degree Fahrenheit hot water. Some of them had been native steam and some of them were running on a more traditional 180 degree hot water so lowering that temperature helped us optimize use of the heat pump for the eastern And then we have two more years where we will complete that transition on the west side. We won't get those buildings all the way to 120. But we will get everything to hot water, including the piping distribution, and then we'll upgrade our existing plant to serve the west side with the hot water system.
Dave Karlsgodt 6:15
Okay, so multi phased project, but you did the big part because when I was there, it was a beautiful campus with people playing frisbee on top of fields and a soccer game going on. But underneath the ground, lots of piping, how many boreholes? Did you get? 300?
Martha Larson 6:29
Total? Wow. Okay, how about 100 of those 94 were horizontal and then the rest are all vertical. So we did make a big mess. Okay, quite a few years there.
Dave Karlsgodt 6:39
Alright. Well, so I love to geek out on these things. But I'm assuming some of the listeners may not understand all the physics fundamentals. So maybe let's let's hit a couple of those first and then we'll go into the how you got this thing built because that's a totally different story, I suppose.
Martha Larson 6:53
Right? Traditionally with our steam system we put in steam in 1910. What's when we centralized our utilities with a central plan? The electric grid wasn't very robust at the time. So steam propels itself through pipes. So you make 80 psi steam and, and through pipes and tunnels makes it with way out to the buildings. So that was traditionally how we did our heating. It was a completely decoupled system from how we did our cooling, which was to run chilled water loops through the buildings and bring that then heated water back to the plant where we just exhausted the heat through the cooling towers. They operated independently. Now by transitioning from Steam to hot water, and using a device like a heat pump chiller, we can take both of those loops, the hot water loop and the chilled water loop into the heat pump together where they exchange that heat. So all the heat we pull out of the buildings with the chilled water loop now gets dumped directly into the hot water loop so we don't have to burn any fossil fuels are the only electricity is pumping energy. And we get essentially free recycled heat. When we have too much heat like in the summer we'll put that down into the geothermal oil fields and likewise in the winter we're able to draw that out. So for about 70% of our load We're able to use the heat pump and the geothermal oil fields to have a extremely efficient use of energy campus wide and then because we're in such a cold climate we are supplementing we have a hybrid systems we're supplementing with high efficiency condensing boilers for peak eating and our traditional chillers that were already on site for peak cooling. Okay,
Dave Karlsgodt 8:18
yeah, I got to see the condensing boiler which looks like a giant like computer
Martha Larson 8:23
Yeah, big metal box. Really a nice clean little machine and and our maintenance staff is excited, they kind of the equipment isn't not too foreign to them. They understand the chiller they understand the heat pump chiller because it's basically very similar. And so I think they're happy that they're going to run a safer and simpler system from now
Dave Karlsgodt 8:41
from now on instead of steam is is
Martha Larson 8:43
quite dangerous. quite complicated. Yeah, right.
Dave Karlsgodt 8:46
Okay. Well, I've been joking with my uncle that if he went to school there and he wants to ever get his name on something, maybe he can't afford a building, but I suppose the side of the condensing boiler might be a place you can get his name if you gave the right amount of donation to them.
Martha Larson 8:59
I've thought about that. I wish I could sell him boiler cause see that would be really fun to have a named boiler
Dave Karlsgodt 9:05
that's what that's one of my dreams too So yeah, we'll see anyway well so okay, we're talking about moving heat around then instead of basically making it twice Is that a good
Martha Larson 9:14
summary of throwing it away from the chilled water system and then making more for heating? We're just recycling it. You could think of it that way.
Dave Karlsgodt 9:21
Great. Yeah. And when I was on the tour, I think with your colleague Fred, he mentioned, you would even talk about like the heat and people getting off like the students,
Martha Larson 9:30
body heat, lighting heat, all these things computers,
Dave Karlsgodt 9:33
you're capturing that now instead of playing into the atmosphere, right,
Martha Larson 9:35
so all of that gets captured by the chilled water loop and then again, brought back to the heat pump where it's dumped right into the heating loop. When we're balanced and we're using the simultaneous modules. Our engineering team tells us that they can be up to 700% efficient so a little bit of electricity to run the pumps because you do have to move the heat around for one unit in that's out seven units out of power and work and energy because We're able to use it for both heating and cooling just by moving it around
Dave Karlsgodt 10:03
and you defy the laws of physics because you're recycling.
Martha Larson 10:05
Yes, we're just recycling it. So what we call an output is really just moving it from one place to another. Okay, okay, well, instead of having to burn more natural gas to create that heat, we just took it out of one building and moved it to another.
Dave Karlsgodt 10:17
Great. Let's talk about how you put this system in physically because this is not like, you know, slapping some solar panels on a building or even retrofitting an individual building. And this is a systematic change your whole campus is what motivated you even think, oh, we should just like rip up our whole campus. Because I'm sure that probably didn't go over. Well,
Martha Larson 10:36
no, it was a process. Yeah, and I will say, Carleton has been very fortunate to have leadership right now that's very process oriented and reflected on where we are as an institution. And so it feels like our strategic planning right now is I'm very stable ground. It's based on really strong foundation. So in 2012, we did a strategic plan that basically said, Carleton doesn't need to grow dramatically. We like what we are as a small residential college. And that led to a campus master plan that reflected those values and said we're going to replace and renovate a lot of our hundred plus year old structures. Even those are less old but not serving us well. And the the focus of the campus plan therefore was on renovation not again growth. That allowed us to then move into a utility planning phase that had a really informed amount of square footage for the next 20 to 30 years. So we didn't feel like we were shooting in the dark here. The goals of that plan were to plan for that campus, you know, evolution that's outlined in the campus master plan that was number one, number two was to replace some equipment that was really at end of life. So major equipment like a steam boiler from the 50s. And we had some tanks and some chillers that were quite outdated, had, you know, R11 refrigerant in them, things that needed to go away. And the third thing was to reduce operating costs and carbon emissions permanently. So those three charges merged into an evaluation of what would happen if we kept the steam Plan and paid for the upgrades that it needs overtime and also continued operating it because it's expensive to operate a plant that has to be staffed 24/7/365 so that we looked at those capital and operating costs against a transition to hot water system. And we started by just saying how water is the basis for all of this, that's the circulatory system. And off of that, we branched a few options, which were different sizes of geothermal into different forms of this hybrid solution. All of that started with a concept study that was not drastically expensive. We did that with MEP associates out of Rochester, Minnesota. And the concept led to a schematic design because we said this looks promising and we have good geothermal resource. We tested our we did a test bore to check that as well. And then that schematic design, you know, we did some cost modeling, we brought in a contractor to do it market pricing. And we also our business office was very involved our budget manager. So the cost modeling was holistic and it reflected Carleton's rates that we like to think of when we do cost modeling and all along that process. You know, we got further and further into it till the point at which the board allowed us to release the base case and say we will not continue to maintain the steam system, we won't invest in it. It's not the technology we want for the next century. Right. And so at that point, we were really released to engage in a full construction document mode to go to the hot water approvals wise and design wise, we went into it with an iterative approach doing the construction again, we phased so that we wouldn't be disrupting the whole campus at once and we did most of the work in the summer so that our students could still have full access to all buildings. The Westfield's did trickle over into the fall, but we prepared the campus with some really strong outreach materials so that everyone knew what was happening and why our beloved quad spaces were closed off. Yeah, that was a big deal.
Dave Karlsgodt 13:44
You did it between Isn't that where graduation takes place? So Fred was saying that you you you started the project like the day after
Martha Larson 13:52
the restore all the grass by the day of the graduation The next year, which was, yeah, it was a photo finish. I'll say
Dave Karlsgodt 13:59
That's good. That's good. Let me stop back or back up a second, because you said, You got the board to agree that the base case was no longer your base case going forward. Tell me more about that. I mean, that seems like that right.
Martha Larson 14:11
So we we had been prepping them with the concept studies. And, you know, I think at first, you know, they were just sort of sitting back and gonna see where this was all gonna go. So I have to thank them for being open minded enough to allow us to do a comparative study. And a lot of them are pretty savvy about potential for carbon taxation and just sort of impact on society. So they've honestly respected what we felt was our responsibility to show them multiple options. And then I think it really folded unfolded naturally into there was a lot of a lot of the hard work was done really behind the scenes internally with our office, our engineers, Fred our VP and treasurer, asking really hard questions and sort of anticipating what the board would need to know. And then when it went to our president, he had to it was very very meticulous about questioning our assumptions. He questioned, you know, our class modeling. And his advisory group was also present for all of those presentations. And so we had vetted it really well before bringing it to the board. And I think the board there, they know that we do undergo these rigorous processes. And so they were also very trusting and open minded when we presented our analysis to feel that they could trust that we had really vetted it before brain
Dave Karlsgodt 15:27
feels like when I was on campus and just talking to your your colleagues and staff and that they're just as a good working relationship amongst the staff. Like I mean, trust each other. It's it's a, it's a tight knit group. Yep. You've done that. I'm sure similar processes you had to go through for those large capital. And
Martha Larson 15:43
we did. Yeah, we've developed and I credit our, again, our leadership and our just campus culture with this atmosphere of trust. And I think that none of this would have gotten off the blocks even in the concept stage if we didn't have that mutual trust. You know, I trust that my leadership when they ask hard questions isn't trying to criticize the work. They're trying to make sure that it's got integrity and that it will hold up.
Dave Karlsgodt 16:06
It's the right it's the right answer for your institution. Not not, yeah, you personally
Martha Larson 16:11
right. And they and they trust me to be thorough with my evaluation and to manage the consultants really well, to choose the right consultants. You know that I was fortunate to inherit a campus culture that was ready for a project like this.
Dave Karlsgodt 16:27
Got it? Okay, because that seems critical to do something. Because you're essentially reinvesting in the veins of the campus, right?
Martha Larson 16:35
Yeah, cold Minnesota winter, right. So everybody needs to be
Dave Karlsgodt 16:41
well, I actually just as a side note, so how cold is it in Carleton? I mean, you're not Duluth but it's not or Bemidji but it's not warm there either.
Martha Larson 16:48
No, I mean, we, we spend lengthy periods of time below zero. And then with the latest polar vortex, you know, will sit there at 20 below for a few days at a time. So this concept of geothermal 120 degrees Fahrenheit hot water, you know, it really was tested and talked about as far as can it handle can extend up to the Minnesota winter. And we, we also another trust building exercise was to do pilot projects. So we did a renovation and mechanical renovation of our chapel. It was on its hundredth birthday, so it had its hundred year old air handling in it. Okay, this is sort of a awesome cast iron sculpture that we pulled out. And then we retrofitted that building with a radiation system that drew off of 120 degree hot water, combination Air Force and radiation. So by doing a building with literally no insulation, except the roof, you know, 100 year old stone chapel, we were able to test it even for ourselves and just say we did one building and that worked great.
Dave Karlsgodt 17:44
Yeah. And that's not a that's a complicated building,
Martha Larson 17:46
complicated building. It's an important building. It has irregular occupancy schedules. So it was a great test building. And so we proved ourselves and our leadership and even our engineers probably proved to themselves that this was going to work
Dave Karlsgodt 17:59
okay. Got it. So I remember in think I saw your presentation at the second nature conference last February, and you talked about your own journey and understanding this systemically. So I mean, you've got the pedigree to understand this. But there's a difference of that and really getting, oh, I see how all these things fit together. And can you describe how you went through that process? And you and your team? Because it wasn't just you?
Martha Larson 18:22
Yeah, it was me and my team. And so they're two concepts that we had to get our heads around. One was, you know, how can it be that efficient? How can it be 700% efficient? And the other thing was, how can we heat a Minnesota winter a whole campus on 120 degree water, which essentially, you know, hot tub is like 104. So we're not even that far off from something that you could actually bathe in, you know. So I think part of it was just having to step back and look at the formulas and the calculations and remember that there are concepts of physics and thermodynamics at play that have been tested and there are you know, the formulas in the in the front cover of your physics book, that's still work. Yeah. And it's, it's just that you need to look at what variables are at play and adjust them to meet the requirements. So as an example, our buildings with the radiation at 180 degree hot water, you know, usually there's a radiator under the window, partly because that's enough to put out enough BTUS. And also, it looks nice to be centered under the window. The engineers basically did calculations room by room of how many of us were required to heat that room. And then how much more radiation how much longer that radiation would need to be to get the same number of bt us so it's a lower temperature, or more time, more surface area just don't get to the same time and you still get the same amount of BTUs and so theoretically, we sort of got it you know, when we had to slow down and just think about it, practically. And then we had to think about in our buildings, you know, each building was different. So some buildings have radiation, so that had to be upgraded. Some buildings have forced air like fan call units. So you know, how do we do it with physical units with each air handling unit? There's different sizes and configurations. So how do we get Bigger coils in the old unit. So we're not replacing the aliens. And in each case, the insurance had a slightly different solution for each building its quirks. And each time they figured it out, figure it out,
Dave Karlsgodt 20:11
they were probably excited to get a chance to figure it out.
Martha Larson 20:15
And then, of course, the chapel project proved it to us in practice, because everyone wants to believe the calculations. But there's still something a little unnerving about just believing something on paper. But as we've gone through, you know, now we've done 10 buildings that retrofits and so it's really, we're quite comfortable with it now. And we're comfortable with the fact that each building is different. It's not going to be a cookie cutter solution to make each building work on this 120 water,
Dave Karlsgodt 20:38
but neither is your steam system, I would suppose right? It was different to begin with.
Martha Larson 20:42
Differently design so it's very easy to equate that and then on the efficiency side, I mean, we just really had to, again go back to the idea of just heat transfer and the fact of the refrigeration cycle and just remember that this is just evaporator and condenser isn't like compressors. It's all the That, you know you have in a refrigerator or even a window box, if you have a window air conditioning unit, you know, it's spewing out heat out the back. And if you can just catch that heat and direct it through metal plates or fins. So again, it's just going back to the things we know theoretically and reminding ourselves that you know, you use those really tried and true formulas, right? Yeah, figure out the solution.
Dave Karlsgodt 21:22
It's been interesting for me to think about, like an air conditioner, like you said, it's it's spewing out heat, and that's its function. So we never think of that as a waste product. If you can capture it, then it's a it's a resource.
Martha Larson 21:33
And it's an input. Right, right. Yeah, exactly.
Dave Karlsgodt 21:35
Now, that's great. And I know the other thing that I've learned is the idea that you don't need to burn gas, which is what you probably know, like 1500 degrees or something when it burns. If you're trying to get hundred degree water, like that's a little bit overkill, right?
Martha Larson 21:49
Yeah, I mean, to make steam we have to combust something. When we looked at biomass, and we looked at high heat content, wood pellets as sort of a manufacturer product It would be a reliable source. It was eight semis a day to do the campus in January. So we thought about truck emissions truck traffic, we thought about warehouses to store this stuff, keep it dry, then we just couldn't imagine operating a facility that way. So geothermal was it was a light bulb moment for us. We thought about it for a building, like a data center where we have cooling loads all all winter, you know, maybe we can have this balance and pick the right building. But then MEP associates did a presentation on Ball State University, which was using the diversity of their campus to balance and that was a light bulb moment for us. So that's what really started our relationship with them was having them come to talk to us about district energy as geothermal
Dave Karlsgodt 22:39
because you're not you're not just running air conditioning in the summer and heating in the winter. You're doing we're doing cooling all the time.
Martha Larson 22:46
Right, right. So we always have a way to exchange energy,
Dave Karlsgodt 22:49
right? so that it becomes like one giant building rather than
Martha Larson 22:52
exactly Okay. That was that was a really defining moment for us to think about geothermal and it's true if you make steam, you have to heat the water to 330 degrees to get 80 psi. You can never do that with solar panels. You can never do that with heat pumps, you can't use condensing boilers, which are, you know, 95 plus percent efficient,
Dave Karlsgodt 23:10
how hot do those get what
Martha Larson 23:11
those are really looking for a return water temperature that will allow those vapors to condense. So you get a little extra boost of efficiency by using both sensible and latent heat. All those great technologies to move heat and to make heat are really built for hot water.
Dave Karlsgodt 23:27
Got it? So you can't use a condensing boiler. If you're making steam, right?
Martha Larson 23:31
It just won't work that way. It won't condense. And so to engage in the future of heating technologies, we just also felt like having the right circulatory system I mean, the equipment can come and go, we can get more efficient equipment, we can get the new technologies in a few decades when our heat pump pumps out, but to have the hot water as the circulatory system is the key to unlocking or access to those technologies.
Dave Karlsgodt 23:52
Got it. So this is an enabling project. Yes, yeah.
Martha Larson 23:55
Not just for today. It's for the future. Yeah.
Dave Karlsgodt 23:57
Okay. No, that makes sense. So I know that the There was a point at which your project got a little bit accelerated because there was a science building that had all of a sudden was coming online and gave you an opportunity to maybe move things more quickly than you would otherwise plan to do. Can you tell me a little bit about that? Sure.
Martha Larson 24:15
Yeah, that was sort of a fortunate coincidence, I would say the two projects were operating in parallel. As part of the campus master plan, there had been an identification that we need to invest in sciences and upgrading our science facilities. And that became a real focus of our fundraising efforts and our presidents sort of call to action. So that building was going to be just we have three buildings built in a horseshoe shape. And initially, it was going to be sort of a fourth addition to that complex. But as the design evolved, they decided to take down one of the buildings that wasn't functioning quite as well for our purposes, and then replace it with the new third leg essentially of the science complex. And our engineers recognize this as a real opportunity to piggyback on a construction project. It was already planned. They're already digging a basement for the science building. If we go one level further, we could build a sub basement to how is the new equipment because we couldn't build the can't take the old equipment offline until the new equipment is constructed. So we actually had to accelerate the progress of our own or utility master plan design to marry that construction of that energy station with the construction of the science building. So I think it was a good catalyst for us. You know, there were it was a little stressful at times after fast track, but but it allowed the college to get more bang for our buck and to also put this station in a place that really works well for the campus. We didn't think people would be excited about placing a new facilities building in the campus landscape. So this really talks it right nicely under owning a building.
Dave Karlsgodt 25:44
And it's really close to the one field if I remember right, right.
Martha Larson 25:47
The other thing is, yeah, it's right on access with all three well fields. So we are able to have the shorter runs of the large piping that goes back to the energy station, right. It's very convenient and also the science building is the highest energy and density on campus. So
Dave Karlsgodt 26:01
No distribution loss if it's in the same, or very little.
Martha Larson 26:03
Right, it's just right there under the building.
Dave Karlsgodt 26:05
Oh, that's cool. Yeah, it was one of the cleanest mechanical rooms I've ever been in. I have to say
Martha Larson 26:10
thank you. Yeah, we're excited about that.
Dave Karlsgodt 26:12
I know it's brand new. But still, I also appreciate it all of the charts and graphs and visuals that you paste it up for the tours, which maybe leads me into my next question, which would be, you had to basically convince the board, we're going to change out the circulatory system for this campus. We're going to spend a lot of money up front to completely change the future. And you can phase it, but I know Fred had said is like you can't do part one with you're not going to commit to part two. So tell me a little bit more about the journey of bringing along your financial oversight team. I guess that would be your board, your CFO, the president.
Martha Larson 26:50
Right. So how we thought about that well, really that for us there's more efficiency was going to hot water course more flexibility for the future modernizing a 100 year old system. But in addition, we had to make cost model, you know, a convincing case that we weren't just squandering money for sustainability alone, or even for facilities upgrades that could be perceived as not necessary. But our operations team plan is quite expensive because again, in Minnesota, the laws are fairly strict about high pressure steam plants needing to have eyes on them all day long. 24/7/365. So we have people working Thanksgiving Day, they're working 2am. They're working on the weekends. And most of the savings are coming from reduction in those maintenance and operations costs,
Dave Karlsgodt 27:36
not the savings of energy. Yeah,
Martha Larson 27:37
the energy savings. Frankly, we are saving about 40%. We expect our energies to go down by about 40% because of the recycling of the heat,
Dave Karlsgodt 27:45
Which is not insignificant. Yeah, that's amazing.
Martha Larson 27:47
But the utility costs given that we're now moving away from natural gas to electricity for the heat pump. Electricity is more expensive per BTU. So the utility costs will go down maybe like you know eight to 10%, but the operations costs Well, maybe 30%. And that's both the repair and maintenance of steam systems, which is just more complicated. But it's also will now have an eight to five staffing model with on call nighttime monitoring. So it's a better work environment for people to not have these changing shifts and working nights and weekends. And it's also a more economical staffing plan for Carleton.
Dave Karlsgodt 28:22
right. If you had to order it, it would be the maintenance, the actual physical operation and maintenance first, then the labor then the energy savings maybe is Yeah,
Martha Larson 28:30
I would do probably labor first. And then kind of the combination of maintenance and energy utility cost savings. Got it.
Dave Karlsgodt 28:36
Okay. Yeah, that's something that's taken me a while to get around to just there's only so much money you can save through energy because it costs a certain amount. That's it like you can save that much but your system costs more than that. Then how do you justify it but that's we forget about, oh, yeah, you still have to run the system,
Martha Larson 28:51
Right, you have the long term savings or the operating costs. By doing the new system. There's an upfront capital cost which which is financed but we will be able to pay the finance Annually with the with the avoided cost. So it's it worked well into our cost model. And then in about, you know, 18 to 20 years, we feel like those two systems breakeven, the incremental cost of the new system breaks even with operating the old one. And from then on, it's just more savings and also flexibility and opportunity to utilize a more modern system.
Dave Karlsgodt 29:19
Right. Okay. Well, and this, this also has the effect of electrifying your system people, you throw that term around, right, but that that's basically what you've done. Right? You switched gas for pumping?
Martha Larson 29:29
Yep, exactly. And that's something we came to again, it was one of our realizations throughout through the process, because people weren't using the term strategic electrification when we started this process. But we ourselves realized as we looked to the future, you know, what would we do? You know, how will this play into the future of our goals, we realized that, you know, electricity is really where you can get really accessible renewables and we we own two wind turbines, we have solar PV, we have solar thermal, so we really aren't familiar with how to make renewable energy. So it became clear to us that that company, With the fact that our utility company has committed to being lower carbon and carbon free by 2015.
Dave Karlsgodt 30:06
So all your all of your electricity sources are getting greener in every way, like your own production on site here youtility the country at large. So that makes a lot of sense. So you haven't completely gone away from gas, right? You're still using gas and the condensing boilers, which is like for really cold days. Yeah. So okay. I assume you still have Bunsen burners in your labs? stuff like that, which is negligible, I'm sure. But you're still using gas. Other any other things that you is this precluded you from running any system that you would otherwise, you know, from your steam system, rather process load you needed to deal with or?
Martha Larson 30:39
Yes, correct. Yeah, that was part of our thought process. And so we have to look at each of those individually. Certainly, we have steamers and kettles in our kitchens and we have boosters in our dishwashers. And so each of those had to be brought to more of a local source. Usually it's an electric sort of steam generator to serve those loads. We had autoclave, the Thankfully, we're already local to the building I you know, I was worried about them until I realized oh, they're already taken care of.
Dave Karlsgodt 31:06
Oh, you thought they were running on this? Yeah, they were actually running
Martha Larson 31:08
actually had their own source. And then we the one area I think where we really got innovative was hot water. We had steam bundles in heating hot water tanks, in our dorms and our buildings just to create hot water for showers and faucets. But also the pools were heated with steam bundles. So as part of this, we had to think about how to deal with it. And one thought was let's put little natural gas Hot Water Heaters in each building, which then marries us to natural gas. Not to mention there's an architectural complication with routing a flew out of these buildings without really disrupting floor plates, and all that was expensive. So we started to challenge that and say, isn't there a better way and our engineers came up with the idea of a plate and frame heat exchanger whereby the hundred 20 degree hot water will pass by one side and the domestic hot water loop will pass by the other side and we can get the domestic water up to about 115 degrees Fahrenheit yesterday treat heat transfer from just by Heat transfer. Yep. And so that was one area where we felt felt we've made a real breakthrough because the pools especially are an area that we are heating them year round. And so all summer when we're pulling heat out with air conditioning, the pools are going to suck up.
Dave Karlsgodt 32:14
And that prevents you from getting out of balance to some extent does
Martha Larson 32:16
it helps the summer loads be a little more balanced. So that was one of our areas where we really had to take a step back and say, Why Why are we marrying ourselves to natural gas? Why would we localize all these little domestic hot water systems? Now the fact that we've tied them into the more district energy system approach just emphasizes really wherever possible to get to a systems thinking approach for all these little details.
Dave Karlsgodt 32:40
So you basically hooked up like your pools and these hot water heaters into your circulatory system that you've built. Yeah, is there any cross contamination risk there?
Martha Larson 32:49
They're separate loops. So they really are there's two pipes that come in, you know, in and out supply and return for the domestic side and then there's a separate supply and return for the heating hot water and the side benefit was all These big huge tanks. Some of them are the size of a small small school bus in their dorms, they got to come out and now we're not holding water. And there's not, you know, kind of crud gathering in the bottom, they're not going to break and flood the door. Around, they're not, you know, they were coated with this bestest insulation. So that sort of whole feature just went away.
Dave Karlsgodt 33:19
And those are probably things you didn't have in your cost model at the beginning, right.
Martha Larson 33:22
I mean, that's a benefit that just came out of the project that that we are now experiencing as sort of a bonus.
Dave Karlsgodt 33:28
That's good. That's cool. Yeah, it was liquid that goes down into the geothermal wells. Let's talk about that. Because there may be some concern of like, drilling holes in the ground, you know, are you fracking or you know, you'll hear people that will say stuff like this, but there is some risk I can get into the water table and things like that. How does it mean, talk to me about Sure,
Martha Larson 33:45
yeah, that we talked about that quite a bit. The liquid that we're using is just water. So our our whole distribution, including the geothermal loop is water. The only thing that hasn't is some biocides which is prevent growth of you know, algae and stuff like that. But it's things that are not it's not working. fragrant.
Dave Karlsgodt 34:00
Okay, that's going to blow your savings by releasing some refridgerant in the atmosphere. Okay.
Martha Larson 34:06
And furthermore, the wells that's basically a piece of maybe one and a quarter inch tubing that goes down and forms a you at the bottom. And that whole thing is encased in concrete. So the whole well is about a six inch diameter that U-bend gets inserted down into that wall and then get filled up with concrete. Right. So it's pretty encased in that each well is fairly well-encased.
Dave Karlsgodt 34:27
If it leaked, you're leaking water. Yeah, correct. Got it. Okay. And then it because I suppose that concrete then prevents the different elevations of the water table from interacting with each other and stuff. Right?
Martha Larson 34:39
That's, that's right, as well. Yep. And we did have to get permits from the Minnesota Pollution Control Agency. We also had an alum, thankfully, that was working for the Minnesota Geological Survey and just was really familiar with the geology. So between that alum and our professors in the MPC a kind of all looking at this together, we were able to get our permits approved
Dave Karlsgodt 34:58
to get that okay. I suppose one thing we should talk about just to get we missed it in our physics discussion. How does that actually work? How do you use the earth? Like, what?
Martha Larson 35:07
How do you actually use the Earth, yeah.
Dave Karlsgodt 35:08
describe the physics of that, because it's not the most straightforward.
Martha Larson 35:11
Well, and the fun thing about this was our, our geologists challenged the engineers on this, the engineers do a test bore and they get the different types of geology, you know, this stratigraphy as you go down, and then they also get they run liquid through it, water through it to get some conductivity values, okay? engineers plug those into a computer model. And there's modeling software specific to projects like this, that will tell them how much linear footage of geothermal Well, they need to marry up with the tonnage of heat pump that besides for our campus, the geologists said, Well, you know, that's not a static value, because groundwater is going to affect that and it's flowing, and it's going to be, you know, different temperatures and different volumes, depending on the seasons. An engineer said, Well, yeah, but we don't have a number for that. So we can't put it in the model. And then geologist said, well, you're being way too conservative. The groundwater is going to make the heat transfer way more efficient than what your what you can assume with a static model. In the end, they agreed to disagree that the modeling, you know, was the best that it could be, and they designed the oil fields to that model, the geologists had to concede that it might be more well that well field than we need. And now what we've done is we have the geologists put in five of the blowers in our main quad, they put a fiber optic cable that they basically attached to the U-bend and sent it down 520 feet, and they can get temperature readings from 520 feet to surface. They're going to study what they can learn from that about groundwater flow, groundwater volume, and temperature, while we marry that up with the data from the oil fields that we're getting through the building automation system. And we'll just kind of see empirically what we can find out about the effect of groundwater flow on the efficiency of the bore fields. So
Dave Karlsgodt 36:51
let me let me see if I can understand that like in the wintertime, you're trying to get heat, you're running cold into the earth and then the Earth would heat it. But if it but if you keep doing that too long eventually like sitting on a park bench You mean that he transfers and it kind of equalizes to, that becomes less effective, but if the water is running through,
Martha Larson 37:08
right, it's sort of refreshing. It's like a battery that's constantly being refreshed Okay,
Dave Karlsgodt 37:13
now that's great.
Martha Larson 37:14
So in the ground for Minnesota is about 50 degrees from from below the frost line down it's a consistent 50 degrees 51 to somewhere in there. So when you're in the wintertime and you're sending you know, you've got you've sent your water through the buildings and the heat has transferred into the buildings the water comes back colder than that like maybe in the 40s so it's going to go down to the earth and get pre heated before going through the heat pump the reverse in the summer we send water down that has sucked all the heat out of the building so it'll go down and it'll be above 50 degrees so it will get pretty cool so the the magic is Earth's temperature is perfectly situated between where we need it to be in cooling heating season and where we needed to be in heating season. So it's always helping us to preheat or pretty cool in addition you know if it does store any in the bedrock there that that can actually Like a traditional battery, where it's gaining heat in the summer and then releasing it in the winter
Dave Karlsgodt 38:04
and that and that, because you're doing it both seasons, it balances out,
Martha Larson 38:08
right? It balances and we will we'll watch that over time. And we'll kind of optimize our system to not overheat or over cool.
Dave Karlsgodt 38:14
And then you can supplement with your other system
Martha Larson 38:17
You can always supplement, which is part of what we liked about the hybrid system was the ability to really trim that that operation.
Dave Karlsgodt 38:22
Got it. Okay. No, that's great. That's that's helpful. All right. last line of questions is more about you personally, because you're not maybe the traditional engineer to just tell me a little bit. How did you get to this base?
Martha Larson 38:35
Yeah, I I always liked puzzles. And I liked you know, I was good at math. And engineering was a good fit for me, but I also liked music. And so I ended up at Northwestern University because I had strong engineering strong music, but I pretty quickly realized that, you know, I had to pick one or the other. It was going to be hard to focus on both and do well, so I picked engineering as the more practical solution. When I got out of school or as I was in school, I realized actually went into acoustics because I realized there was an engineering field related to mechanical engineering, designing buildings that are built for musical performance theatre, etc. And so I really I started with Kierkegaard associates, which is a pretty prominent acoustics firm in Chicago had done an internship with them. And it got me into the world of construction and design and big buildings. And so I learned about how large projects happen and how fundraising happens. You know, the fact that they have an owner's representative and a project manager as well as architects and acoustical consultants. And so I really got a ingrained into the construction industry through that first job. And then with acoustics being such a narrow field, I moved to project management I worked for a company called the rise group, which was doing large municipal Performing Arts Art Museum projects. And my my last job there before moving to Carleton was the St. Louis Art Museum expansion. So, again, really complicated projects with a big team coordinating a lot of people and in that role, I was an owner's representative. I was assistant Project Manager, there was a senior project manager who mentored me. And I feel like that really gave me my project management chops. Because those were stressful jobs, big jobs, lots of stakeholders. And so coming to Carleton, I felt prepared for the complexity of the projects. But it was just the focus on environment was where I wanted to move with my career. Just knowing the crises that are rising out there. I feel like it's all hands on deck, everybody needs to be working on the environment right now.
Dave Karlsgodt 40:28
Well, I hope that people listening to this episode will appreciate the diversity of your background put it you know, putting the puzzle pieces together the you have a grace about the human side, as well as the engineering side and just I mean, it's it's just really, I'm in awe of hearing how you've put that together. I see so many projects that don't have that approach. And it's I think that's a testament to how you guys got this done. So thanks,
Martha Larson 40:51
Dave. Yeah, it's always about people to and communicating what you're doing. Not just barging in.
Dave Karlsgodt 40:58
Right. Yeah, exactly. No, and Well, maybe then I'll leave that as the last question. Tell me more about how you're communicating this project out to the world. Now I know you've seen, there's maybe some charts and graphs that we can share on the podcast website. Do you spend How much time do you spend talking about it like this?
Martha Larson 41:13
Quite a bit, actually, my colleague Alex Miller, and I spent a lot of time we hired a graphic designer to help us with our charts and graphs. We did a lot of dorm outreach, we did a lot of communicating with the campus community before, during and after the project. We've done a lot of presentations at conferences because our our goal is to keep our campus community informed and appreciative and also just to be able to celebrate with us the big accomplishment that Carleton has achieved. And it's also to help others who are following in our footsteps not have to deal with you know, basically let them benefit from our lessons learned is the the point and
Dave Karlsgodt 41:50
they don't have to be the first one in Minnesota to do this because you've already done that.
Martha Larson 41:54
And we'll learn from them too, because each one is different and each person each institution is going to take a different approach and have different tweets. But that's very important for us to make sure that everything we've learned will put it out there so that more projects like this can be constructed. And we'll all learn from each other.
Dave Karlsgodt 42:09
That's great. Any any big new projects on the horizon? You guys have a flux capacitor in the works, or
Martha Larson 42:14
the next big idea is always the next question. That's on my mind. Get two years left to phase two. But I certainly am thinking about how we're going to provide that electricity, renewables. So I think renewables behind the meter is really where my mind is at right now.
Dave Karlsgodt 42:30
Very good. Well, maybe in a couple years, we'll come back and talk about that project. Sounds great. All right. Thank you very much. Yeah.
Martha Larson 42:34
Thanks, Dave. Yeah.
Dave Karlsgodt 42:36
Well, that's it for this episode. In addition to Martha, I wanted to give a special thanks to Carleton's VP and Treasurer Fred Rogers, who led the tour of Carleton's district energy system during the next conference in September, as well as my colleague Kaia Findlay, who edited and produced this episode. You can find more information including photos of the geofield under construction at our website at campusenergypodcast.com. If you want to keep up with this podcast, you can follow our page on LinkedIn. We offer this podcast as a free service. But if you'd like to support the show, please share it with your friends and colleagues or take a minute to write a rating or review on iTunes. As always, thanks for listening.