Notes

James Bingaman is a graduate research assistant in the Department of Earth Environmental Sciences at Michigan State University. He studies agrisolar and other renewable energy designs and their impact on groundwater recharge, water resources, and ecosystems. In this episode, he will discuss how smarter solar design can be better integrated with farms and natural systems to boost ecology and viability while meeting the energy demands of the future.

Links to learn more about James

• James on LinkedIn
• James on ORCiD

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Transcript

BRAD NEWBOLD 0:00
Hello, everybody, and welcome to We Measure the World, a podcast produced by scientists for scientists.

JAMES BINGAMAN 0:05
When our lab talks about agrisolar, generally, we’re talking about any way that you’re integrating solar infrastructure into an agricultural landscape. And then it can also include things like agrivoltaics, which is traditionally when you actually integrate the farming practices with the solar arrays. So they’re, like, either underneath the panels or they’re in between the panel rows or even like ecovoltaics, which is a newer term that is really like looking at how we can use the arrays for specifically ecosystem services and promoting things like biodiversity, things like that, which can also have a great benefit for agriculture as well. When we talk about agrisolar, we kind use it as an umbrella term that really tries to incorporate all these different ways that we can use solar for multiple benefits beyond just electricity, specifically in, like, an agricultural landscape.

BRAD NEWBOLD 0:57
That’s just a small taste of what we have in store for you today. We Measure the World explores interesting environmental research trends, how scientists are solving research issues, and what tools are helping them better understand measurements across the entire soil plant atmosphere continuum. James is a graduate research assistant in the Department of Earth and Environmental Sciences at Michigan State University. He studies how agrisolar and other renewable energy designs on working landscapes can support groundwater recharge, water resources, and ecosystems. And today, he’s here to talk to us about how smarter solar design can be better integrated with farms and natural systems to boost ecology and viability, not just kilowatts. So, James, thanks so much for being here.

JAMES BINGAMAN 1:48
Thanks for having me. This is this is great.

BRAD NEWBOLD 1:51
Alright. So we love talking with our guests and hearing right off the bat how they got into what they do.

JAMES BINGAMAN 1:58
Sure.

BRAD NEWBOLD 1:59
So if you wanna give us a little background as to how you got into sciences in general and how you found your way into, you know, agrisolar and renewable energy.

JAMES BINGAMAN 2:10
Sure. Yeah. So as far as science goes, I think I was always interested in science when I was a kid, but I initially kind of didn’t go that direction professionally. But I always loved being outdoors. A key moment for me was actually, a trip I took out to Utah. I was, hiking in Canyonlands National Park, walking around, and the landscape was just so different than anything I was used to. I had never seen anything like that before. So I was sitting there eating my lunch, and I was just like, I had these questions. Like, how did this get here? Why does this look this way? And so I went back home, and I was living in Evansville, Indiana at the time. And right in town is University of Southern Indiana. And kind of on a whim, I looked up classes there. And so they had a geology of the national parks class and decided to enroll in it. My job at the time did some tuition reimbursement, so I was able to go basically for free. And then I took that class. The professor Paul Doss was great, and I ended up talking to him constantly after class. And so he ended up convincing me to kinda go all in on it, I became his research assistant and his teaching assistant. And we started doing research together on groundwater in Michigan and how that related to landscape change there. And so that project really got me curious about landscapes and the impact that landscape has on hydrology and groundwater resources. Yeah. So I think that’s where I where I really got my start. And then when I was looking for grad schools afterwards, after I graduated with a geology degree, I met Anthony Kendall at Michigan State University, in the hydrogeology lab. He told me about this cool project that they were trying to get funded where they were looking at how these solar landscapes change hydrology and what that could mean for groundwater resources and what that could mean for farmers and, you know, agricultural practices. And it just sounded really cool. It got me really excited. It’s kinda where I ended up where I am now.

BRAD NEWBOLD 4:12
Would there be a point in that trajectory where where you realize that agrisolar design could be lever in changing landscape use as opposed to just not some, like, fun idea or something along those lines?

JAMES BINGAMAN 4:27
Yeah. When I first heard about it, when I first talked to Anthony, my adviser, about it, I mostly had questions. It wasn’t immediately apparent to me, like, what the changes would be, but we talked about it and then looking at some research and some of the literature. I think just once you start to do some of the math and you you do the mass balance and you realize that the water has to go somewhere. And if if we change the system so that less of it’s evaporating, like, it it has to go somewhere. And and whether that’s a good thing or a bad thing, you need to figure out what that is and where it’s going. So I think it was once I started looking at the actual math of it and just looking at it as as the system. When you make those changes, it’s there’s gonna be consequences, and it’s just a matter of figuring out the magnitude and what they are.

BRAD NEWBOLD 5:20
We should probably back up a little bit. And Sure. For those who are not well versed in in this particular research field, let’s define what agrisolar actually means. It was a new term to me a couple years ago, and I’m sure there are probably lots of our audience who aren’t quite sure what agrisolar means. Could you just give us kind of a a quick background into that definition?

JAMES BINGAMAN 5:45
The definitions get a little contentious. There are some people that have different ideas about what different words should mean. When our lab talks about agrisolar or when I talk about agrisolar, generally, we’re talking about any way that you’re integrating solar infrastructure into an agricultural landscape. So that could be colocating, on different parts of the land or next to fields or in parts of fields. And then it can also include things like agrivoltaics, which is traditionally when you actually integrate the farming practices with the solar arrays. So they’re, like, either underneath the panels or they’re in between the panel rows or even, like, ecovoltaics, which is a newer term that is really, like, looking at how we can use the arrays for specifically ecosystem services and promoting things like biodiversity and things like that, which can also have a great benefit for agriculture as well. When we talk about agrisolar, we kind of use it as an umbrella term that really tries to incorporate all these different ways that we can use solar for multiple benefits beyond just electricity, specifically in, like, an agricultural landscape.

BRAD NEWBOLD 6:47
Within your research here, what counts as kind of, like, a better integrated, you know, design as opposed to just, like, throwing a solar panel there and and calling it good? Is there a defining point where you’re I I don’t wanna say, like, greenwashing or whatever, but but something that is genuinely resource enhancing. What does that look like? What kind of design is is that looking like?

JAMES BINGAMAN 7:14
Yeah. So I think in the broadest terms, I think you’re looking at what space are you using. It’s easy for a developer to come into a area that has a lot of agriculture and farming and and just pick a random space and put in a bunch of solar, and it’s gonna make a lot of electricity. Agriculture and solar really do compete for the same land. They’re looking for sunny, flat places. The first step is really thinking about where you’re putting it. Because even in what we would call prime farmland or good farmland, not all of it is created equally. You know, there are different portions of a field that won’t produce as well or different portions of a field that are harder to farm or maybe are having, like, soil issues, soil health issues. I think the first step is figuring out how to put solar in a place where it’s not taking away from the agricultural landscape in general, kind of balancing the benefits of both. And then the second part of it is is when you’re actually thinking about how you design the array to how it’s going to affect the landscape around it. So there’s different changes you can make to an array’s design that might impact how things grow underneath it. It might impact how things grow next to it. But it’s gonna impact how it interacts with the soil and just, the general landscape and hydrology. So, really, I think it’s just conscientious design and choices about where you put things.

BRAD NEWBOLD 8:41
One follow-up question to that is that Yeah. When when you’re talking about designing, you know, renewable energy infrastructure on the landscape, what are some of more underappreciated design decisions that end up mattering for water resources and positive outcomes for ecosystems?

JAMES BINGAMAN 8:59
It’s really just about what you’re designing for. So when you’re designing a standard solar array, you’re really looking to just maximize that per panel electricity generation. So, generally, that means that you’re trying to get those panels, like, pretty far apart from each other so that you have zero shading. You’re trying to optimize that angle to, like, catch as much sun as possible, whether that’s in a tracking system or in a fixed axis system where it’s just held still the entire time. I think you can start thinking about is electricity generation the most important thing, or at the top end of that electricity generation, like, how much electricity is it gonna cost us to make some subtle changes that could have big differences for the landscape around it? So things like how you space the rows of panels or what angle you put them at. And there’s been a lot of cool innovation with that. The advent of bifacial panels where they can actually produce electricity from either side, whichever side light hits it on, have been really great. I’ve allowed for some really unique, like, vertical designs and things like that. So so I think it’s about being creative and and not valuing only the electricity generation. Because then if you start to look at what the other benefits you can have, you can make a difference. I think an important thing to think about with solar in general is that these are thirty year installations, typically. These are long term changes you’re trying to make to the landscape. And so anytime you’re making long term change like that, you wanna think about what those long term consequences are gonna be. And so little changes over time can make a really big difference for something like water resources.

BRAD NEWBOLD 10:40
So let’s jump into your current research project. And actually, the the location is one thing that I wanna start with, where Yeah. You’re working in Southwest Kansas.

JAMES BINGAMAN 10:51
Yep. Just outside Garden City.

BRAD NEWBOLD 10:54
I want you to kind of paint a picture for us about what that what that location is like, why that’s an important for for this test case, Why is it is it an interesting location for this intersection of agrivoltaics and also, you know, water resource management?

JAMES BINGAMAN 11:14
Yeah. So Kansas is is really a great place to work for a couple reasons. First off is the Kansas Geological Survey is a really great organization that’s been doing a lot of great research on groundwater out there, you know, forever now. And so we’re partnering with Sam Zipper at the Kansas Geological Survey and University of Kansas for this project. And so he’s been fantastic to work with out there. Kansas is, special because they produce a massive amount of agriculture, especially Southwest Kansas is farm fields as far as the eye can see. And they’re dependent on these groundwater resources from the High Plains aquifer in order to irrigate their crops. And that irrigation is really important for their profit margins. Whenever they aren’t able to irrigate or if they have to decrease the amount that they can irrigate, there are real ramifications for farmers’ bottom lines out there, which is challenging, especially considering the depletion of the High Plains aquifer and the challenges that they’re going to face to that groundwater resource in the next decades. In certain parts of the High Plains aquifer, like the Central High Plains aquifer, it’s possible that irrigation could be impossible or very difficult as soon as the next, like, thirty years depending on which projections you’re looking at. So there are is a kind of a limited time span on how long this resource might last if we don’t find ways to either conserve or, like, enhance the resource. And then also Kansas is interesting because they do have some a significant amount of renewable energy out there, but it’s all wind. Like, I think forty percent of the grid out there is wind energy in that region, but they have very little solar. And they’re starting to develop it now. But because they don’t have a ton, it means that there’s opportunity there for as they build solar and as solar increases its share of the energy infrastructure to, like, make some early design decisions where you could really make a difference for the community in the long run. An issue with solar development in general is sometimes that it can feel extractive to the communities that it goes into. So developers will come in, and and they’re trying to do their job, but they’re not bad guys in this situation necessarily. They’re just coming out and trying to, you know, find good land that can support a solar array and build it. But often, it comes at the expense of, you know, what they view as their landscape or, you know, they don’t really feel like they get a say in it, or it’s not really tailored towards them. And so because so much of Kansas is agricultural, it’s really a good opportunity to try to present, like, a new way of approaching the problem and a new way of meeting kinda people where they are and trying to show them a different way to do things that can really have more benefits for everybody where we can provide them with clean energy that will help kinda decarbonize our energy systems, but then also give them a way to maybe make some more money, whether it’s through, like, a lease of their land or whether it’s through them owning arrays and getting direct payments from it. So there’s kind of this intersection of issues in Kansas in terms of water resources, the need to decarbonize the energy system, and then also the need to support farmers and the agricultural industry out there in a way that’s sustainable for the long term. And broader, that’s really important for the whole country because they they just grow so much of our food.

BRAD NEWBOLD 14:47
And you mentioned earlier that and especially with solar, I mean, you mentioned wind there as well. I mean, we’re we deal with that here in the on the Palouse of Eastern Washington where, you know, we have consistent winds, we’ve got, you know, we’ve got wind farms all over the place. And for better or worse, you know, there’s some pushback, you know, against against having those here from especially within the the agricultural region that that we live in. But you did mention that agriculture, and especially there in Kansas, agriculture and solar are kind of looking for that that same landscape. Like you said you said, sunny and with, you know, lots of consistent sun, flat land. Also, you know, there’s that overlap between oftentimes solar and areas that have less in the way of water resources as well, if that’s I’m just kind of working my way around. So I again, places that are that are more arid or other other places like that, where where water is a a much more necessary resource, and especially when you’re dealing with agriculture there, if you’re dealing with irrigation and other things like that. So there’s some some pros and cons about that overlap between the landscape that that is available and and how to use that.

JAMES BINGAMAN 16:05
So we’ve actually looked at this a little bit. We used water scarcity product, and we kinda mapped it over the world. And then we overlaid it with a global horizontal irradiance, which is generally equivalent to, like, how much solar energy can you produce in a place. It’s a little more complicated than that, but roughly. And they really line up really well. They match really well. All these places that are gonna face water scarcity in the next, you know, ten, twenty years are all places that really have a lot of potential for solar electricity generation. And so if we can find solutions that marry those two ideas, I think it could have a lot of benefit, a lot of places. But it’s it’s so individual on place and climate as well.

BRAD NEWBOLD 16:51
So Let’s jump in. And and and one of the cool ideas, and I guess this had never really crossed my mind until I was reading some of your some of your research there, is usually plots of land are designated in in grid form, in some kind of square or rectangular form. But when you’re dealing with irrigated agriculture, especially on those large plots, you’re dealing with pivot irrigation, which are circular, usually. Can you tell us about this idea of having kind of your the corner of your pivots having better use for them than just kinda sitting there, I guess, fallow or unused?

JAMES BINGAMAN 17:30
So I don’t think that we’re the first ever to think of it. It it’s something that’s come up before. I think there was a paper out of Colorado that mentioned it as a possibility at one point. So I think other people have thought about it, but I don’t think it’s ever been implemented broadly. And so we still think it’s kind of an opportunity that we could take advantage of. But, yeah, you’re right. These pivot irrigation systems, they they pump that groundwater, and they distribute it really efficiently in terms of how much water they’re using to how much crops they’re growing. But the place that’s inefficient is in the land use. So you end up with, like, eighteen percent of the field is just these empty corners. And some people do find other uses for them. There are, like you know, some people use it for conservation land, and they can get a small stipend for that. And some people use it for storage or cattle grazing and things like that. But by and large, if you look at them, they’re they’re largely underutilized. They’re pretty empty. They’re mostly overgrown. They come out and mow them every once in a while, or they just kinda let them go wild. Yeah. It’s a big space of land where we’re talking about this idea of agrisolar and how do you incorporate solar onto an agricultural landscape in a way that’s kind of beneficial for both, and this seems like a really good opportunity where, you know, they already have this land. It’s sitting pretty much empty. Like, what more could they get from their land?

BRAD NEWBOLD 19:05
That surprised me too, that that eighteen percent number. I mean, that’s nearly a fifth of of their land being used for something other than agriculture, and, you know, that’s mainly what they’re making their their money off of is is Yeah. The crops that they’re growing and selling. Right? And so so, yeah, having that that kind of extra land land use or that extra land available for other uses is seems like a I I don’t wanna say it’s an easy an easy and nothing is easy, right, with with this situation, but but at least it’s something that’s available for other uses and something that maybe these growers would be able to help out economically with with their situation.

JAMES BINGAMAN 19:47
And and there are challenges to it too. It’s not it’s it it’s not without its It’s not a plug and play situation. Right? Yeah. You you know, you need the infrastructure there. So you need to be able to get the electricity from these corners to the grid. And so to do that, you do need to somehow get the infrastructure and the transmission lines that would be able to connect all these corners up to the grid in a way that right now, they’re not. You know, a lot of the pivot irrigation systems are electric now, and they’re moving that way largely. But that doesn’t mean that the infrastructure is there and ready to go. So for a utility company, sometimes it it sounds more appealing to just cover a couple big fields full of solar, and then you it’s it’s much easier to manage that infrastructure and build that infrastructure. But we think there could be potential to, you know, use a more distributed, at least sometimes, energy system, and you could see some benefits.

BRAD NEWBOLD 20:45
Yeah. I I had a couple questions on on some of the actual, like, the hydrology and the hydro hydrological science be behind, you know, agrivoltaics and or ecovoltaics. And can you walk us through a little bit about and I think you mentioned you’re calling it kind of, like, water balance rewiring when it comes to, like, trying to figure out what happens once a photovoltaic system is installed and how, you know, precipitation kinda shifts and infiltration and and, you know, evapotranspiration and all that fun stuff and groundwater storage. I mean, we’re talking about, you know, aquifer recharge and all that kind of stuff. Can you talk about kinda, like, mapping that out and beginning to kinda model some of this information?

JAMES BINGAMAN 21:34
Solar array really has kind of a roofing effect that’s pretty unique. So it creates this impervious surface that goes over pretty much the whole field. A typical standard design solar array, about forty percent of the land surface is covered in solar. So you’ve got this roof effect that happens over the field. And so as far as inputs go, it does two things. It concentrates precipitation. So it takes precipitation that would have fallen on those the panels, and it concentrates it all at a drip edge at the front of the panels. And so you get these this heterogeneous distribution of precipitation. And so the the second input that changes is you get a significant amount of shading on the field, which which makes sense, and conceptually, it’s not hard to imagine. But the the consequence of that is that you just get less evapotranspiration. So there’s less energy coming in for evaporation, but then also for transpiration for the plants underneath there. And so the combination of that concentration and then that decrease in evapotranspiration changes the water balance. So, usually, you you’ve got precipitation or your input is gonna end up equaling your change in storage plus your runoff plus your evapotranspiration broadly. Right? And so if we are decreasing that evapotranspiration but our precipitation is staying the same overall on the field, then we either have to have more storage or we have to have more runoff. Right? And whether that runoff is subsurface or, you know, above ground, either way. And so the water has to be going somewhere. So there’s a lot of research that’s been done. And if you go to kind of an agrisolar talk or an agrivoltaics talk, most of them will talk about soil moisture, and most people find that there’s an increase in soil moisture underneath their solar arrays. So the the ground is just more wet. There’s more water in it. And so the question we kind of have and wanna look at and try to quantify is is that water going anywhere beyond just that soil moisture? Like, is there also percolation happening down and creating groundwater recharge that wouldn’t have happened otherwise because we have these water conditions under the panels? And so there’s there’s kind of the broadly, that decrease in evapotranspiration is where that potential comes from. I think one other way that I think is interesting and is kind of smaller and maybe not as consequential, it’s not the the big part of it, but is that rainfall concentration at the drip edge. So when you get a smaller precipitation event, say, that would never reach beyond the very surface of the dirt, it would it would just be at that top surface, and it’d be captured by, like, even just the the leaves of the plants above ground, and then it would evaporate off of them most of the time. Right? In those situations, you actually get a significant concentration of precipitation right at that drip edge. And so you can actually see saturation happen in these lines along the array at much lower in much smaller precipitation events. And so think there’s also potential for that to create kind of some more actual soil moisture storage, but then also potentially percolation depending on how that works out. And so I’m curious about that as well, but it’s a little bit harder to constrain.

BRAD NEWBOLD 24:53
So let’s talk about some of the experimental design that you’re working with. So you created a two plot scale, you know, analysis here in this situation where you have kind of an electricity first design and then a water first design. Can you go into a little bit, yeah, a little bit more detail just kinda describing about each of these arrays’ purposes and what you’re what you were looking for trying to measure in contrast?

JAMES BINGAMAN 25:22
The real question that we’re trying to get at and that we’re trying to answer is is how can array design change the hydrology? So we’re pretty sure, pretty confident, the math makes sense that more recharge should happen, and there should be more recharge no matter what kind of array you put down. Right? There’s less evapotranspiration. And so our question really is, well, how can we maximize that, and what are the trade offs? And so for our experiment, we decided to create kind of two different array designs. So we built two plot scale arrays. The first one is exactly how any solar developer would build you a fixed tilt array out in Kansas. It’s pretty spaced out panel rows. The panel rows are tilted at a thirty degree angle to catch as much sun as possible throughout the year. And we kind of know what to expect from that in terms of the electricity generation. So what we decided to do is we decided to kind of turn all the knobs that we could to maximize the potential for groundwater recharge. And so we created the second array that’s really focused on that groundwater enhancement. So to do that, we we increased the ground cover ratio. So we made all the panels kind of closer together so there’s less space in between the rows. And then we also decreased the tilt a little bit partly because it more consistently captures precipitation that way. When rain falls, you know, depending on which way the wind’s blowing, it’s gonna come in at an angle. And so you could either come in it could either come in perpendicular to the array and a lot of precipitation be captured or it could come in parallel to the array and almost no precipitation would be captured. So that flatter angle lets us capture more precipitation. And then to to take advantage of that, we’ve actually guttered the fronts of each of the rows so that we can collect the precipitation that hits the arrays. And then we’re we’re routing it to a kind of subsurface infiltration gallery where it goes actually into a perforated pipe that’s below the root zone and kind of dodges all of the evapotranspiration potential that we possibly can to deliver as much water as we can to the subsurface.

BRAD NEWBOLD 27:35
How are you measuring some of these parameters? Earlier, you talked about wanting to be able to to check on evapotranspiration or soil moisture or infiltration percolation, those kinds of things. What are how are you going about doing the actual on the ground measurements of those kinds of variables?

JAMES BINGAMAN 27:56
Yeah. So we’ve got a pretty large network of instrumentation out there trying to kind of keep an eye on water and energy fluxes. And so underneath the arrays that we kind of have divided up into these multiple zones of areas that are shaded and areas that are sunny and then areas that are dry and areas that are wet. And so you get these different combinations of those two kind of parameters. And so underneath the array, we have pyranometers that are measuring solar radiance. So we can look at how much solar energy is actually hitting the ground underneath the arrays, in between the arrays, and at what time. We’ve also got soil moisture sensors that go down just about a meter almost. And so we’re keeping an eye on soil temperature and soil moisture at different levels and different depths. And then we’re also looking at kind of the microclimate underneath the arrays. So we’ve got the kind of temperature and humidity underneath the arrays in case there’s any differences there. Everything we would really need to kinda try to constrain evapotranspiration as best we can without directly measuring it. And then we’ve also for the entire area, we’ve got kind of a meteorological station out there that’s collecting wind speed, wind direction, precipitation, kinda all your standard stuff. But we have so many different zones and so many things out there that it’s a massive amount of data that we’re collecting right now. So we’re collecting, I think, it’s around twenty six thousand data points daily right now. And so it’s it’s been a big undertaking to kind of, like, get that data, you know, quality controlled and analyzed. And I’m really grateful for, our team at KGS who’s been mostly handling that for us. Those are kind of the a lot of what we have. In order to look at that kind of deeper percolation, though, we also have three borehole NMR tube setup. And so they go down thirty feet. And so KGS goes out there once a quarter, and they’re running their, NMR sensor down those tubes and kind of looking at soil moisture at depths up to thirty feet. And so we’ve got one of those in our standard array right at the drip edge where we think we’d get the most kind of potential for recharge. And then we’ve got one in the control zone just so we can kinda constrain what a standard field would do for recharge. We don’t think it’d be much, but if it is there, we need to take it into account. And then, also, we have one right by our infiltration gallery to see how much water is actually getting down into depth.

BRAD NEWBOLD 30:24
I don’t think we’ve talked much about NMR in our discussions here. Tell us a little bit more about or just a little bit detail about about what that what that does and and what it’s looking at.

JAMES BINGAMAN 30:38
KGS is largely handling that for us. But the way it works broadly is that we have this borehole of PVC that goes down about thirty feet that we drilled out and pushed into the ground. And so they back up their geoprobe their truck with a geoprobe, and they dangle this geoprobe down this thirty foot hole. And they they slowly lower it. And through the wizardry of geophysics, they can give us a lot of really cool information. And one of those one of those bits of information is is estimates about what the soil moisture is for that area directly around the tube. And so we can we can see really at depth much easier than we would from any kind of, you know, handheld instrumentation. There’s just not a good way to get that far down and see soil moisture. So it lets us look into a space that we wouldn’t have been able to look at otherwise.

BRAD NEWBOLD 31:36
That sounds for is that nuclear magnetic resonance? Yeah. Nuclear magnetic resonance. Okay. Got it. Sweet. That’s a a new thing for me. I’m always super interested in in a lot of the the tech that’s out there. And I and I have to ask from as being part of METER Group here, what kinds of METER Group instrumentation did you have out there in your in your setup?

JAMES BINGAMAN 31:59
Sure. So METER instrumentation, we’re actually using mostly for kind of our soil characterization. So we’ve got all this data that we’re collecting kind of passively and is constantly coming in. What we’re using METER stuff for mostly is actually trying to, like, understand the soil characteristics. So we’ve between us and KGS between MSU and KGS, we have, like, four SATUROs. And so every time we’re out in the field, we’re basically constantly running SATUROs. They’re they’re always somewhere, and then, like, we we take brief breaks to go refill the water and run them somewhere else. So we’ve been trying to figure out our saturated conductivity using those and figuring out if it’s gonna change anywhere, you know, through kind of changes in the the soil from being underneath these arrays. And then also, we take samples for our HYPROP. So our lab has a HYPROP, and we’ve been using it to kinda get that the unsaturated hydraulic conductivity, which is really important for us for when we start to look at modeling these things. So we talk about trying to figure out how much less ET happens and how much groundwater recharge happens. And all those things I mentioned, we don’t actually have a way to directly measure that. And there’s not really a good way to directly measure that. With a plot scale array like this, you’re not gonna see just changes in the water level in the well at the where they’re irrigating at. Right? It’s not gonna have that big an effect. So what we’re trying to do is we’re trying to constrain all these other variables so that then we can build some hydrologic models to try to get good quantifiable estimates about how much recharge and ET is happening.

BRAD NEWBOLD 33:48
What are the underlying hypotheses that that you’re trying to test out about where the water goes and how long it stays available? What are what are those looking like right now?

JAMES BINGAMAN 34:01
The depth to water is pretty large in the area we’re working in. So the timeline for water getting there is pretty long on the the range of, I would think, years probably. But I think the benefits could still be there in the long term. I mean, we’re looking at years for how long we have to continue to use that resource. Our hypothesis is that there could be a significant amount of recharge that happens even if you don’t do, like, the extreme version of the array that we built as our kinda groundwater enhancement array. I think, ideally, the the perfect answer might be somewhere in between where we’re prioritizing both electricity and groundwater enhancement. The hypothesis we have is that if we find that sweet spot, we can really produce a single amount of electricity, but then we can also get most of the benefits for the groundwater recharge as well. And so I think some of the back of the envelope math right now is that if you filled all four corners of a field with our groundwater enhancement array, the the amount of water delivered to the subsurface, how much of that goes to straight to groundwater versus, you know, ends up in soil moisture storage, and at what timeline, not sure. But it would provide as much as, like, ten to twenty percent of the irrigation needs for that field potentially as subsurface water. It’s not going to solve all of the problem, but we think it could be part of a solution.

BRAD NEWBOLD 35:23
Right. And so some of the the, I guess, early signals from the field there, you’re you’re saying that there is some evidence that these, I guess, recharge optimized arrays can enhance, you know, recharge and with deeper soil moisture. What are what are some of these these most convincing early indicators that you’re seeing that there can be the enhanced recharge and water availability Sure. In in on the landscape there?

JAMES BINGAMAN 35:52
We’re still early in the project. So we just built these arrays in August. So since August, we’ve kind of done two NMR borehole measurements. And so the one we did when we first installed the arrays kinda gave us a baseline. And this most recent one that we did in December actually showed a significant increase in soil moisture right beneath where we’ve got our infiltration gallery. So so far, we’re starting to see that soil moisture increase at depth just beneath kind of the root zone. And so we’re really excited to keep running those tests and see if we can see that wetting front start to move down that thirty foot tube. So we we it looks like it’s starting, but time will tell.

BRAD NEWBOLD 36:35
Alright. We’ll see. And like you said, you started that in August, so it’s been, you know, only a few months at the time that we’re recording this. So we’ll we’ll check back with you in a few months to years and see see hopefully, not years. But you you did mention working and modeling the situation. One of the issues that, I guess, would would come up in this in this situation is you’re you’re dealing with kind of, you know, heterogeneity of of the the the landscape there. Like you said, you’ve got roofing effects and other things going on. You have the various different situations with the different arrays working there. Yeah. How are you dealing with with that kind of issue when it comes to spatial heterogeneity and trying to model the the hydrologic, you know, fluxes that are that are happening in in those spaces?

JAMES BINGAMAN 37:27
Yeah. So the approach we’re taking right now is we’re we’re trying to use one d modeling at the moment, which is complicated a lot by that heterogeneity you’re talking about. Ideally, you’d wanna use two d or three d potentially. But our goal is to build these models that we can make very repeatable for lots of different places because I think I’ve mentioned is is we’d love to scale this up and kinda see what could the regional impacts be, so beyond just a single farm. And so we’re trying to come up with ways that we can model this efficiently. And so one way we’re looking at is we’ve we’ve we’re collecting all this data for all these different zones, and so we’ve got that for kind of ground truthing. But then we’re also running models that aren’t hydrologic models but are, you know, solar irradiance models. So something commonly used in kind of the solar development side of things and is these irradiance models. And so we’re utilizing them to actually look at how much solar radiation hits the ground underneath. And so we’re using a Python package called Bifacial Radiance right now to kinda create these data points or models models of solar radiance underneath the array. And so combining that with a model that we built for trying to look at how much how that precipitation is divided up and that heterogeneity and the precipitation based on wind, wind speed, and direction as well as the amount of precipitation. We’re looking at trying to figure out how can we define these clusters of areas, the these spatial areas that kind of have common hydrologic features. So they get similar amounts of precipitation, similar amounts of shading, and then create kind of individual one d model zones for all of those different areas that we can kind of cumulatively sum up to see, like, a net effect overall for the array.

BRAD NEWBOLD 39:15
Got it. So you’ve got these hydrologic zones that that you’re working with in order to model model those out. You also talked about you would prefer to have two or three d, you know, multiple dimensions that you’re that you’re working with. Is this something where where you feel like the data that you’re gathering, you’d be able to kind of expand these models into something a bit more robust and descriptive or even predictive?

JAMES BINGAMAN 39:44
Yeah. So I think what we would like to do is if we could I think it would be nice if I could compare the method that we’re trying to create right now with these one d models to a two d model or a three d model and kind of do both because there are real advantages to the one d model in terms of computational power and also just the inputs. We’re using HYDRUS right now. And so for HYDRUS one d, there’s a Python package, and there’s a way to use Python to kind of automate a lot of the process for the models, which makes running them much more efficient and faster and makes expanding them to other areas and other farm fields as a tool much easier than it is to use, like, the two d models. And so I think if we can maybe use a two d model to validate kind of the one d model, it would be really great in terms of being convinced of the robustness of the method. But I think there’s real advantages to potentially being able to look at the region using one d models if we can kinda dial it in and make it as accurate as possible.

BRAD NEWBOLD 40:46
You’ve mentioned also that ground cover ratio is is kind of a a key element here as well. Is there a rule of thumb when it comes to design about, you know, ground cover ratio and and especially when you’re dealing with kind of these agrisolar in these pivot corners and those kinds of things. What might a a a rule of thumb be or multiple rules of thumb be for for that situation when you’re dealing with ground cover ratio?

JAMES BINGAMAN 41:18
Ground cover ratio is gonna be variable depending on where you’re at. So depending on your latitude, kinda north south is gonna change how closely you wanna space your panel rows. So as you get further north, the sun’s gonna be kinda lower on the horizon even at midday. And so you kind of need that extra space in order to make sure that you’re not shading between the panel rows. Because when you shade, like, part of a row, you get a significant decrease in electricity generation because depending on how your inverters are set up and how it’s all wired together, a lot of times, your string of panels will only get generate as much electricity as the, like, smallest, least efficient part of it is. So if you get shade part of it, it actually decreases the whole row’s efficiency sometimes. And so for Kansas and kind of these mid latitude regions, a forty percent ground cover ratio is pretty typical, so pretty well spaced out. You know, there’s more space between them than there is distance of the the panels. So it’s diminishing returns. So as you start to increase ground cover ratio and start to move those panel rows closer and closer together, you’ll start to see small deficits in electricity generation at first just from them being a little bit closer together and, like, a little bit of shading happening at the early part in the late part of the day. Then you you get closer and closer together, and eventually, it drops off a cliff, and you get very little electricity generation because they’re just right on top of each other. And so the per panel efficiency goes down as you get them closer together. But I think one thing that’s interesting that hasn’t been explored as much, and I think there are some developers trying to explore it now, is that we don’t necessarily have to look at it as panel efficiency. We can also look at it in terms of how much electricity are we getting out of, you know, a square mile of land. Because as you pack these rows closer together, they may be producing less electricity per panel, but you’re also fitting more panels in the same amount of land. And so what ends up happening is you can sum depending if you can find a sweet spot, you might be able to actually produce more total electricity. The downside is that you have more infrastructure to install. You have have to pay for those solar panels up front. But one advantage is that solar is getting really inexpensive now. So the cost of solar panels is way down compared to where it used to be. I think in the estimates we were getting for building our solar arrays, honestly, the racking was a lot of the cost. So these kinda, like, steel and aluminum racking units that hold the panels were actually the more expensive part. And so so costs have come down significantly. So if you can find efficient ways to produce this racking, you could potentially get just as much or more electricity off the the certain amount of land as you would have before. It just might be less per panel.

BRAD NEWBOLD 44:14
You were mentioning about seasonality and the farm use, and I I’m just thinking about about if you have any any thoughts on those trade offs that that farmers and utilities will have to make. The ultimate goal is is you want them to be working together in order to improve, you know, electricity production as well as agricultural production. Right? Other ways when it comes to, like, the seasonality of things about you’ve also mentioned, you know, tilt angle and how productive can the land be, and are there ways that the solar arrays can be, you know, out of the farmer’s way type of thing, you know, or being able to to work within them or under them. We’ve talked with others who were working with, you know, agrisolar or ecovoltaics about about how to use the land underneath the the solar panels. You know, we’ve we’ve had somebody who is working with, you know, grazing of sheep or trying to figure out about livestock and how to have livestock underneath those and other things like that. I don’t know. If you could kinda maybe talk about, yeah, the trade offs or that both the utilities and the growers might want to investigate as they are going about, you know, developing these projects.

JAMES BINGAMAN 45:25
I do think that there are some benefits that could could happen. One aspect is gonna be the management. So, you know, you build the solar arrays, and then there you have to manage them afterwards. And so you mentioned sheep are a really popular way in agrivoltaics to kind of manage the vegetation underneath these arrays. You send in a herd of sheep, and they eat all the grass underneath, and you kinda move them around different arrays and periodically clear it out. And it’s a lot easier than having to mow. It’s a dual use, which, like, we’re always in favor of. But there are other things you can do. I mean, I think it would be really cool if we could find ways or if it’s possible to include maybe pollinator habitat underneath some of these arrays, and that’s a really common way that people have tried to apply agrivoltaics or ecovoltaics that has benefits for the farmer as well. But there is gonna be kind of that challenge of of managing in between there and kind of making sure it stays both out of the way of the farmer and the the common practices they have to do as well as is still producing enough electricity to be worthwhile. One thing that we are measuring for that I haven’t mentioned yet is we’re looking at soiling. So soiling is basically how much, like, dust and dirt accumulates on the panels. So we have a soiling sensor out there. And one thing that we’re curious about looking at is how much soiling occurs at different times of the year. So farmers have harvest seasons and different harvest practices. And depending on the crop, they can sometimes be throwing up a ton of dirt into the air, a ton of dust, whether it’s, you know, plant dust, plant matter from, like, you know, threshing or something like that, or whether it’s, like, digging up potatoes, for example. There’s a lot of potential for that. And so trying to identify, like, what kind of negative impacts that could have for, you know, the utility company or whoever’s running those solar panels, and then, like, how do you mitigate that, and how often do you need to go out there and, like, you know, clean your panels or something like that to maximize your generation. Also, I think there’s potential to for farmer practices to change a little bit in terms of if we can sync up when we’re producing the most electricity from these solar arrays with when farms are using the most electricity. Right now, a lot of the farm is is still powered off of, you know, diesel and natural gas. Right? A lot of these big farming equipment. We haven’t electrified those yet. But I think in an ideal world, assuming we can make enough batteries for it, you know, and the battery technology comes along, I I think electrifying most things makes sense. And so if we can get to a point where we can be powering kind of these farm practices off of these solar arrays and doing it in a way where they sync up and we don’t have to worry about that, you know, excess generation during the middle of the day that doesn’t get used because we can use them on the farms, I think that has a lot of potential too and is, like, a down the road great thing to explore if we can get the implementation figured out.

BRAD NEWBOLD 48:19
I was wondering, what are some of the other adoption incentives that both the growers and the utilities might have in the situation to be able to to work together to set up a a system like this?

JAMES BINGAMAN 48:35
For farmers, it’s gonna be just another source of income. Farming is really hard. I mean, they do a ton of work, and they’re not always guaranteed a good outcome. You know, there are drought years, and there have been some really significant drought years just recently out in Kansas. And those can have big impacts on your crop and your profits. And so the nice thing about incorporating solar onto your farm is the potential to have kind of a steady income. So if you can get a significant steady income, it can really float you through some of those harder years and make it easier to kinda come back. And that can be really important, especially for small farms or, you know, small family owned farms where one bad year could really knock them out and make it really hard for them to continue their practice and continue farming the way they’ve been doing for generations and the way they want to. So the big benefit for them is is hopefully adding some resiliency. So whether that resiliency is coming through increased water resources, and that water resource could be from them producing more groundwater recharge that then lets them continue to have water to irrigate. But it could also be through, you know, policy change where, like, farmers that are using practices that help increase groundwater recharge, maybe they get some credits for being able to continue to irrigate or irrigate in a responsible way. And so that could let them continue to irrigate longer than they would have been able to otherwise and kind of, like, augment their water rights, I guess. And this is all hypothetical, hopeful future kinda talk. Right? But then also resiliency in terms of economics and making sure that they can continue to afford to farm and kind of weather those drought years that we’ve started to see more and more of recently. For the utilities, I mean, I think the advantages are not always as obvious, but I think there’s some there. So one nice thing about distributed solar when you don’t have it all just in one place is that when you get a cloud that passes over one area, you’re still producing electricity somewhere else. And so it kind of levels out the grid. One concern with solar that people have is that it can be producing a ton of electricity sometimes and then no electricity other times. Right? And that can be a a real concern with trying to manage the grid and making sure that people are getting electricity when they need it. And so having it distributed like that does kind of buffer some of those swings that can happen in electricity production. I also think incorporating it onto farms is potential for farmers to work with them and, like, you know, have someone out there who is kind of already a land manager, someone who already cares about the land, is already taking care of the land, is going to be out there almost every day, and they’re gonna see if there’s a problem with the solar array. They’re gonna, you know, be able to take care of the land the way they always have in a way that I think could benefit the utility who cares about their infrastructure staying usable.

BRAD NEWBOLD 51:25
So Right. I guess what are some of the other constraints about scalability when when it comes to a setup like this and that you’re that you’re proposing here?

JAMES BINGAMAN 51:36
Scalability? Honestly, there’s more corners than we need to produce the electricity we need out in Kansas. Right? Like, we’ve got a lot of land out there. It’s really picturesque. If you go to our our experimental site and you stand and look at our two arrays, you can actually see in the background, there’s a coal power plant right there. And it’s got a capacity of, like, three hundred and fifty megawatts or so. And so to get just the same nameplate capacity as that, you actually only need I think it’s, like, fields worth of pivot corners. And so, like, to put in context just the county we’re working in, they have, like, a thousand five hundred pivot irrigated fields in just the county alone. And so it’s one of those things where, like, there’s plenty of land that’s in these corners that we could use for solar. For us, I think one thing that we wanna think about is, like, which of those corners gonna have the most benefit. Right? So which of those corners are, you know, a sandy loam that might have a higher conductivity and produce more recharge versus, you know, something that’s got more clay and is gonna, like, inhibit that. And so I think being strategic about not just using corners, but, like, which corners we use could be important in terms of making sure we’re kinda maximizing the potential.

BRAD NEWBOLD 52:58
Right. With it, as we’re kind of wrapping up, I got a couple questions about application Sure. Elsewhere. So, yeah, if you were to kinda generalize beyond these pivot corners, if we, like, zoom out from even from Kansas or how how could your findings, I guess, translate to to other landscapes? So whether it’s dry farming or rangeland, you know, even, like, orchards and vineyards, other places like that, do you do you see the the any possibilities for for those kinds of applications?

JAMES BINGAMAN 53:32
Solar has been agrivoltaics has started to kinda become more of a thing, and there’s lots of places where we’re looking at using that. Orchards, you mentioned, is a great example where people are starting to look at, can we put solar in these orchards and kinda, like, increase our productivity of these plants, especially in a changing climate? I do think climate has a a lot to do with it. So a lot of agrivoltaics that has happened so far has been in kind of the arid west where things are cons like, it’s water constrained. Right? And so decreasing that energy means you have more water. I think when you move to more humid kinda temperate environments, that’s where I still have a lot of questions about, like, what will the consequences of that be? Like, there might be areas where trying to increase the groundwater recharge with your solar array might not be a good idea. Here where we are in Michigan, things are very wet. There’s a shallow groundwater everywhere. Not everywhere, but a lot of places. And so if you if you’re increasing the recharge there too much, I mean, maybe you start to see more erosion than you want or, like, higher water tables in a way that isn’t as beneficial. So I think it’s about being conscientious and trying to take the kind of lessons learned there. But then when you apply them other places, you really have to look at the place and really take an inventory of what’s there and what the climate’s like and what the landscape looks like. I think it could look really different if you went somewhere else. And I I think that’s something that our our lab is curious about and is, like, wanting to continue researching in, like, our future projects.

BRAD NEWBOLD 55:05
We really haven’t touched much on the ecology side of things as well. And what do you see might be the benefits on ecological outcomes when it comes to ecovoltaics? Or we’ve been specifically talking about about agrisolar and agrivoltaics here, but we haven’t really touched on the ecology side of things. You mentioned, like, pollinators and and having other things, soil health, all that kind of stuff. How might design choices intentionally target those kinds of outcomes that probably should deserve equal billing in many places?

JAMES BINGAMAN 55:40
Sure. So I think it’s gonna it’s gonna dictate your design a little bit. So, you know, we talked about ground cover ratio and how you can kinda control how much solar energy is hitting the ground and getting to those plants under there. And so it really comes down to, can you get a good balance of light for different plants to, like, thrive and live in these, like, optimal conditions while also still making sure that they get enough water. Right? That you’re not concentrating too much water and moving water away from where those plants are so that you don’t just get single strips of good vegetation. There have been some really great studies that have looked at biomass and kind of the impacts of that on grass underneath solar arrays. One person we’ve tried to work with, Matt Sturchio, has done a lot of work on this. He’s graduated now, but his PhD adviser, Alan Knapp, they’ve done some really great work out of Colorado on that. Yeah. So I think there’s a lot of exploration that can still be done there. I think we’re really only starting to scratch the surface. And at this point, we’re really just starting to kinda measure the the results of building solar arrays. You know? We’re building these solar arrays, and a lot of the studies that we’re doing are going out there and seeing how it’s changing things. And I really hope that the next step after that, once we kind of understand how these changes work, is that we can get to a point where we start designing for them, where we start designing our solar arrays with specific things in mind, like ecology, biodiversity, and just, like, supporting the landscape as it exists and how it could be.

BRAD NEWBOLD 57:14
Right. Okay. Hypothetical. Say a solar developer comes to you, James, and, you know, tomorrow and said, hey. We wanna build, you know, we wanna build something that is a setup that is better for for water, for ecosystems. What would be your three to five item design brief that you would give to this individual? What would that look like? What would be some of those key points that you would you would want them to hit, whether you’re talking about, you know, ground cover ratio or tilts or roofing effect or you talked about the gutters and Yeah. And other things like that.

JAMES BINGAMAN 57:55
So it it’s complicated. It it depends definitely where they’re at. But it’s a great question because those are really the things we’re trying to figure out. Right? Like, those are Right. Those are the the kind of takeaways we wanna be able to give people from the science. I think right now, the thing I can say for sure is, like, thinking about your vegetation management plan beforehand. You know, having an idea of, like, what vegetation you’re gonna have under there and whether the way you’re building your array is gonna support that or not. And so trying to come up with a plan in terms of, ideally native vegetation that’s that’s going to be able to thrive under those conditions, whether you’re in a humid climate or an arid climate. Can I talk a little bit about something, like, we’re looking at doing in the future? Yeah. Yeah. So for this project, you know, we wanna scale up and we wanna look at, like, what the kind of regional consequences of these kind of designs could be. But a separate project that kind of we’re looking at for my PhD is really, hopefully, eventually getting to the point where we can build what we would like to call the agrisolar lab or an agrisolar lab, where we have replicate plots of different solar designs, where we can really try to answer these questions that developers might have. So in terms of, like, what are these trade offs between ground cover ratio, what are these trade offs between panel tilt, and also, like, different vegetation management plans or the different type of vegetation you could grow under there. And what are the benefits not only for the landscape, but also for the electricity production? What are those trade offs? And so right now, we’ve got kind of the seed funding from Growing Convergence Research grant from the National Science Foundation that my adviser, Anthony Kendall, wrote the proposal for and is kinda, like, the lead PI on. And so we’re super excited about that and working on that and hoping that we can keep this thing rolling and get it to the point where we can actually build this lab out at MSU that would let us answer those kind of questions directly and tailor some of our work to the questions developers have. The thing about science and especially the science I wanna do is that I I want it to have a benefit for the world. Like, I want there to be outcomes that are applicable. I want it to be able to be applied. And so part of that is communication and being able to, like, tell people about your research and, like, show them how it matters to them. And then some of it is also finding out what people need to know, making sure that we’re asking the right questions in our science. And so I think that’s a big part of it, and I think that’s something that that we would love to continue to do.

BRAD NEWBOLD 1:00:34
Awesome. Along those lines, final question, say a policymaker, a grower, a solar engineer, they’re all listening to this episode because, I mean, our audience is is wide and varied. But what is one key takeaway you would want each of them to walk away with from this discussion or from from what you’ve shared from your research?

JAMES BINGAMAN 1:01:00
Really, it could be the same key takeaway from all of them, but it’s it’s just to be creative in how we try to solve these problems so we don’t have to do things the way we’ve always done them. And there are lots of innovative ideas out there for how we could implement these kind of solar landscapes in a way that really benefits everybody. And I think if we kind of work together, there’s a lot of potential for benefit for everybody and for the land and for the long term. So I think not getting kind of locked into doing things the way we’ve always done them, trying to envision a future that’s a little different and thinking about what you want that future to look like.

BRAD NEWBOLD 1:01:39
James, any final thoughts for our audience? Anything else you’d like them to to know or remember from the really cool research that you’re doing? You know, you had your your two panel arrays. Anything surprising, or were they kind of did did they did they kind of meet expectations when it came to the the results there?

JAMES BINGAMAN 1:02:00
So the first part of my master’s has really been designing these arrays. So, you know, I showed up at MSU, and kind of the first thing I did was just a ton of literature review trying to figure out Yeah. Answer these questions about array design and, like, what are the consequences of different array design? As a master’s student, I was really kind of given just free rein on that. And so I was going to these meetings, and I was showing up. And I was like, oh, here’s this idea I have for a design, you know, like, kind of sketches and ideas. It’s been really surreal to get to August. And all of a sudden, those things that I had just been drawing were, like, built and in the real world. And it’s been really cool to see something actually get created off of kind of the work you were doing and kind of the research you were doing And have it be real and in the world. And so getting the data and seeing the data come in has been so enjoyable just from the standpoint of, like, getting to see the process from the very beginning and the kind of the conception. So I’m just really excited to see how it turns out and how the data supports, supports our hypothesis.

BRAD NEWBOLD 1:03:00
Awesome. Well, our time is up for today. Thank you again, James, for being here, for having this discussion. We really appreciate you taking the time to to share your research with us, and it’s been a very interesting conversation.

JAMES BINGAMAN 1:03:15
Yeah. Thanks for having me. It’s been really great talking to you.

BRAD NEWBOLD 1:03:19
Awesome. And if you in the audience have any questions about this topic or want to hear more, feel free to contact us at METER Group dot com or reach out to us on X at meter_env. And you can also view the full transcript from today in the podcast description. That’s all for now, and we’ll catch you next time on We Measure the World.