Land Stewardship in the Solar Industry | Rhett Kerby, KerTec | #67

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Power Hour, environmental reclamation and land stewardship. I'm Tim Montague, your host. You know, here in the solar industry we are putting large solar farms across the United States and these range in anything from 20 acres to thousand plus acre projects. We now have some gigawatt plus scale solar coming in to places like Texas and Indiana. There's a 1.6 gigawatt power plant being developed in Indiana that is a 13,000 acre solar farm. And so we need, we in the solar industry need to be very concerned about what we're doing with the land both during and after construction and helping that land to become an environmental good, not just a power generating facility. Of course there's many positive attributes to power generating facilities from solar, wind and battery storage, but, but the land is a major component of this and there are so many other positive impacts to converting land from cropping, for example, or grazing to solar farming. So we're going to get into that today. My guest today is Rhett Kirby. He's the founder and principal at a company called Kertech out of Lubbock, Texas. Welcome to the Clean Power Hour, Rhett.

Thank you Tim. Thanks for having me.

Really great to bring you onto the show. As you know, as we discussed early in our first conversation, I'm quite involved in the pollinator friendly and multi use movement to use solar farms for agrivoltaics, for example, or pollinator friendly landscaping that's as environmentally and ecologically friendly as possible. And so when I saw you posting some beautiful photos on LinkedIn, you know, I was attracted to your work and so give our listeners a little bit of background on yourself and your company.

Sure, absolutely. So educationally speaking, undergrad from Texas Tech in plant and Soil science, graduate degree from Iowa State in plant and soil science. After college, actually during my undergrad work, had an internship with USDA which turned into nearly a 10 year career where my sole task was stabilizing highly erodible soils for the Natural Resources Conservation Service. And with that came the use of pollinator friendly habitat, wildlife targeted as establishment projects. You know, so it was really a, it was really where I had really had an on the ground experience in taking disturbed land and converting it into something that was ecologically sustainable and had value from a wildlife standpoint or, you know, multiple different goals from an erosion control standpoint, from a pollinator or endangered species standpoint, there were multiple goals of the projects that I was involved in. And then after that, in about 2011, I had an opportunity to manage a native seed company. And that's really where I was exposed to the beginnings of solar and wind and this need for plant and soil science, the discipline of plant and soil science in the construction industry. At the seed company, I was having conversations daily with engineer, civil engineers, electrical engineers do it, civil contractors doing dirt work. I was having conversations with people about their need for seed. And if you follow me much on LinkedIn, you'll know that I break what I do into kind of two different categories. You have exoteric and esoteric. And so what I was seeing from the construction industry, this very exoteric need, meaning that it was very, it was very binary, it was very not well understood. It was, it was like I need a seed and that's the end of what I need. And you know, and as a, as a, as a soil scientist, you know, I ask questions about that seed or about that project, you know, what kind of habitat or environment are you going to be placing that seed into? You know, much like you would a garden, you know, if you just go by the vegetable seed, that doesn't make you be successful. You really have to tend to that soil to ever end up with vegetables. You have to. There's a whole lot of other criteria to having vegetables beyond just buying the seed. And so what I was seeing was you have an industry that has a tremendous impact, millions of acres of potential impact. And the conversation was about feedback. And it wasn't long before, you know, I was, I saw seed being used and not being planted correctly. And it was just a bad reflection on, you know, it didn't speak well to the seed industry. It didn't speak. No one was benefiting from these failures. And so it was in 2014 that that this kind of brainchild, you know, kind of came to be between me and my brothers that, you know, we really need to take our, our practical education and practical experience and try to apply that in a construction setting. And so, you know, we're much more. I say we, me and my brothers and the people that work here, I mean, we're scientists, but we're also, we also apply the science. I mean, we're, we do a lot of applied science. And that to me is what makes us different, is that we have an understanding of the background and the need for certain things, but then we have the ability to execute that. And that's really different than what you see in the industry today. You see, you see, you see the scientist and then you see the applicator, and they're two separate roles. And I find a lot of conflicting bias when you separate those two. You know, you have a scientist that may have, you know, they have great intentions, but then you have a contractor that has a budget and is always looking for opportunities to, you know, improve their, their margins. And so, you know, when you, when you place those two bias in the same project, it doesn't always have the best. It doesn't position the project for success because, you know, the bias are just conflicting. And so by being the scientist that actually is able to execute the science in a way that's beneficial to the project is, you know, I think that's unique to what we do. You know, we can write plans, we do consulting, we show up, we have the equipment, we can do the work, we monitor. You know, we do all the things that ultimately provide results for the project. And that model doesn't always fit well or fit. I shouldn't say it doesn't fit well. It's. That's a. Contracting against a model like that is somewhat challenging because from a, from a developer or general contractor standpoint, you like to hand off big chunks of. Especially as a developer, you want to hand off the development to a general contractor. And sometimes a general contractor may or may not have the technical expertise to know how to handle the things that we do. And so, you know, that's really a long.

Let me stop you there.

Yeah, go for it.

You've given us a lot to chew on. And. Yeah, so let's kind of step into this in a stepwise manner. You've got a site, it is being developed. The developer will develop a landscaping plan for pre. During post construction. And those plans vary in their level of specificity and detail. But broad, broad strokes, there's a plan. And like here in Illinois, we have a pollinator checklist and you know, developers are developers and their contractors are hiring landscaping, landscape engineering firms or environmental engineering firms to come up with a species list that meets certain criteria, that is going to produce not only good pollinator habitat, hopefully, but also be very constructible, have a low cost of maintenance. There's many considerations, right. And money is always a constraint and that gets weighed with value. Right. And sometimes you're getting more value for your money and sometimes you're getting less value for your money. And. And while you might think, oh well, if I have to do pollinator friendly, this is going to be more expensive, well, you might be surprised how expensive turf grass is in the Midwest. The amount of seed, for example, required to get turf grass established is very high relative to pollinator friendly seed mixes, for example. And then for the long haul, you have to think about, okay, what are the runoff implications, what are the habitat implications, what are the cost of maintenance implications? You're going to do less mowing and less maintenance in general of the landscape once you get some native plants established on a site in general. So from those, from that perspective though, okay, you have a plan, you have a site. And tell us a little bit about how you approach this. What are the considerations and what do developers and contractors need to be thinking about as early as possible? Because that's the thing is we don't like surprises and we don't want budget surprises either.

Understood.

Tell us a little bit about that front end. How do you de risk a project?

Yeah, how do you derisk a project? That's a great conversation. You know, the plan, as you mentioned, you know, I think it comes depending on who you're talking to. I think it has different titles, but, you know, you can have a reclamation plan, a landscaping plan, you know, you can have. But I think to me, the goal in the planning process to de risk a project would be that plan, whatever it's called, needs to have a component that's very closely related to what you find in the stormwater prevention plan, and that is the erosion control component. Because there will be a time where that project is exposed to erosion and that erosion can remove the topsoil that provides the topsoil is the vehicle that is going to allow for vegetation to be expressed. So if you're not stabilizing that topsoil or you're not taking care of that topsoil during construction, you may have a risk in losing that topsoil. So you have two risks there. You have the risk of that topsoil ending in a river. So that's now you have a compliance issue. But you also that that event, that discharge event of sediment off site means that that sediment is what I call topsoil. So that sediment is now off site when it needed to be on site. And so that is a risk of losing topsoil. To de risk that there needs to be some sort of erosion control planning. And that's not in my opinion, that's not sediment barriers like on the edges of say silt fence to catch it before it leaves. That's great as a last final measure of protection. But ultimately have a erosion control plan that stabilizes the topsoil where it was originally. And so there I understand there may be grading that needs to take place. And so as far as de risking the grading work, you have cut and fill areas, you have areas that you have material that's cut away, then you have areas where you put this fill material. Those are very highly susceptible to erosion and or highly susceptible to non expressing vegetation because you're effectively turning the ground up upside down, you're placing subso on the top, which subsoil is effectively inert and not able to express vegetation very well. So there needs to be planning considerations given for your cut and fill areas related to fertility, related there again to erosion control, stabilization. Those are really a couple of the biggest risks that I see in the beginning is understanding what does it look like to keep this site stable during construction.

And when you're doing cut and fill, are you recommending then that additional topsoil is brought in from off site to counter that problem of the soil being turned over or how do you counteract that?

The best way to counteract that is to harvest your topsoil and stockpile it. So if you know you have an area, you've got say 100 acres that you're going to cut, well scrape that off. First you've got to understand what topsoil is. So after you understand what topsoil is and the depth of that topsoil soil, take that layer, scrape it off and stockpile it to the side. Remove your material and then put your topsoil back. And now you've got topsoil. And another risk factor is compaction. So compaction is, it needs to be defined. I've had this conversation with construction contractors as far as compaction is concerned and I really had to leverage, I really had to kind of go back to the textbook and figure out what, what is, what is compaction related to vegetation expression? Because to a contractor that's out there with heavy equipment they may, I've been told, well, I didn't compact it. That means he didn't roll it with a heavy vibratory roller. But it's still compacted just from the sheer nature of driving on it with the equipment that he drove on and on, drove on and with. So compaction from a soil science standpoint is anything over 200 psi. So once you hit 200 psi roots, the root establishment begins to decrease. When you hit 300 psi of compaction at the root zone, vegetation cannot exist. Roots cannot penetrate 300 psi. So 200 point. 200 psi is where root establishment begins to decrease. It will decrease till you hit that 300 psi point and then it will stop. And so compaction is something that must be addressed in these plans. There's an astm, I can find it for you. There's an ASTM soil compaction test with using a penetrometer to measure soil compaction. That is definitely one thing to do because you place seed even in good topsoil. But it's hard that seed doesn't have the physical power to push through compacted soil. So understanding compaction is important.

And then on the erosion control side, what is, what is a best practice and how does that best practice vary by region? You know, because I know that you're working in a, in a pretty wide swath of the Great Plains down into Texas and you know, I don't know if you've gotten into the, into the upper Great Lakes, but, but erosion is a major, a major concern. I'm glad you pointed out the difference between the silt fence versus you know, treating the entire area in some way because really that, so fence is a last ditch emergency to, you know, emergency preventer to keep soil on site, but you don't want it to move at all. As little as possible, basically. Right?

Absolutely.

Soil is gold. And the argument that I'm making about solar farms is that yeah, you're taking corn and beans here in the Midwest and converting it to steel piles in the ground and glass panels on top. And, and after 20 years you should have organic farm ground. If you treat the soil well, if you do pollinator friendly and low herbicide or pesticide treatments during the course of maintenance. So how do you control erosion?

We'll be back after a quick break.

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Yeah. So to me, based on where you are in the country and the criteria that I use as we work in different areas of the country is really a rate of evaporation to precipitation. So that that dictates a lot, that dictates how forgiving your environment will be. For instance, in Texas you have a very. Texas exists right in the threshold from one extreme to the other. On the west side you have about 150 inches of evaporation and 10 inches of rain. So you could do the math there you're a 15 to 1 ratio of evaporation to precipitation. And as you that that evap, that ratio begins to change. As you go east, you where you hit 1 to 1 is somewhere around I35. So you've got 1 inch of evaporation to 1 inch of precipitation. That's that. That to me is where things, the level of forgiveness begins to change. As you go east of that line, you begin to have less evaporation and more rainfall. So you have the inverse in that ratio. So you may have 50 inches of evaporation and 60 inches of rain or some number to that effect or 20 inches of evaporation and 40 inches of rain. So you begin to have a different set of challenges with that. You may have a higher road water erosion potential, but you also have a higher potential for vegetation expression because you have a more conducive, more greenhouse like climate to establish vegetation. And so depending on where you are in the state and that i35, you can really kind of take that all the way north and use that as a line as to what challenges you're going to see where. So as far as from an erosion control standpoint, if you're west of that line where you have a deficit of evaporation to precipitation, it's going to be very hard to establish vegetation quickly because you're in a moisture deficit nearly all year long. You will be able to establish vegetation, but it's going to be in A very short window of opportunity throughout the year, maybe a rainy season, that sort of thing. So your stabilization methods may need to consider what I call mechanical stabilization, like mechanically placing something on the soil, like straw or hay or hydromulch or some sort of mulch material that actually is going to preserve that topsoil in place. As you go east, you may have an opportunity to use vegetation to quickly establish and provide erosion control. You have to take into account your soil characteristics and some other things, fertility. You just can't put seed out there and expect it to grow, which I've experienced that. And if there's no fertility or grounds too hard, you can put seed out and it gets rained on, it just doesn't grow because the soil now becomes a limiting factor as you're going west.

And it's getting more xeric though, isn't wind erosion a major concern also? So on the one hand, the drier and dustier it is, right? Then you've got major dust control problems and wind erosion problems. And then as you go to a wetter climate, you've got water erosion concerns. Either way, it's a major challenge. Right, understood.

Yeah, yeah, absolutely.

So, yeah, I know that during construction, for example, in Nevada, we're involved in bidding a project where we have to provide constant water to the site to keep the dust down during construction. And that's understandable, right? It's very, it's very dry and dusty. So that's, that's the nature of the beast out west.

Yes, it is.

So. Well, what, let's, let's talk about some of the best practices just real quick, like soup to nuts. We only have a few minutes, but. But what, what is your company practicing or what are you seeing others doing, so to speak? That is a full wrap. And providing for long term low cost maintenance and good solar construction.

Yeah, absolutely. That to me, that is the service that we want to provide is a turnkey solution that offers long term. When I say long term, I'm talking 30, 40 year sustainable practices. And that can be a combination of, of pollinator species, of native grasses, that can be a combination of whatever the goals of the client are. But ultimately a couple of things. Soil stabilization, decompaction, fertility and then vegetation that is suitable to the goals of the client. If I was to ask what my recommendation would be as far as vegetation is concerned, I'm always going to lean on natives because they are the most highest, they have the highest chance of probability, highest probability of success in being able to express vegetation after construction. And they offer the lowest maintenance costs going forward. Some of our modeling, because we do mowing and maintenance on solar farms too. Some of our financial modeling or forecasting shows anywhere between a 40 and 60% save savings over the life of a 25 year project. If you front load some of those O and M costs in the proper establishment of good vegetation or project specific vegetation that allows for minimized O and M. If you front load and provide a good establishment budget, you're going to see potentially 100% return on that by decreasing the cost of O and M over time. And so you know, that is a very hard sell because you have different siloed. You have a construction budget and you have an O and M budget. And I'm talking about shifting one to the other. And that gets really, really confusing. But there are some of our clients that do have long term investment or vested interest in seeing a project be low cost and low maintenance over time. So it makes sense to have that conversation about shifting a little, shifting some of those funds, construction to allow for proper establishment, proper erosion control, proper expression of vegetation. And so with that comes the conversations of compaction, fertility, soil health, all of those things that are needed for vegetation expression. So I kind of gave you a long answer.

What does it take to get native plants established? Here in Illinois we have a rule of thumb that it takes three growing seasons of. And you're doing mechanical control and chemical control to keep the weeds down. Weeds are major pest here in the Midwest, very fertile soil. And they will quickly just completely take over a site if they're not controlled rigorously early in the establishment phase. What do you see? What do you see in, in your parts of the country?

Yeah, an integrated pest management approach is. And that really needs to be part of that plan that you were referring to is a pest management plan post construction or post establishment. And you're right, there is mechanical means of weed control and chemical means of weed control. And depending on your interest level in herbicide use, if herbicide use is not an option, then obviously you're going to have to compensate for that with mechanical use or mechanical weed control through mowing and string trimming and that sort of thing. But if herbicide use isn't a tool in your toolbox, that is the quickest way to achieve a satisfactory stand of native grass is with herbicide use in three years. You know, three years is, I think that's a standard across the country. You may have weed problems in, say the Midwest, but you may have dry conditions farther west that just prevents. You just have minimal growth. So maybe your three year window in the west is related to stature and your three year window in the eastern parts of the US are related to weed control and just management regarding the competitiveness of the vegetation in the area.

So are there other aspects of stewardship that you want to highlight for our listeners?

Erosion control is in my opinion from a stewardship standpoint. As a land steward that's practiced for a really long time. Erosion to me is kind of the staple of stewardship. Erosion control is a staple of stewardship and that's wind or water erosion because depending on where you are, you may have either or both. And as a steward, preventing that erosion is an indication that you're on the right path to successful establishment of vegetation. So to me it really does begin with stable soils. Then you can have a conversation about compaction and fertility. But if your soils are unstable and they're blowing and washing away, it doesn't even allow for you to have conversations about these other things. So I would say the first place to start is really with stable, non erodible soils.

Very good. Well, we'll put a link in the show notes to your company website. Thank you and your LinkedIn profile. Our listeners can find all of our content at the Clean power hour@cleanpowerhour.com you can find us on YouTube, you can find us on Spotify, Apple, Google, any of the major audio players. So please subscribe, give it a thumbs up or a like and reach out to me. I love to hear from my listeners and we're always looking for guests to come on the show. So if you know somebody who has an innovative product or solution, please reach out to me. You can find me on Twitter, TG Montague or on LinkedIn. I want to thank Rhett Kirby for coming on the show today. I look forward to learning more about your work and let's grow solar and storage.

The Clean Power Hour is brought to you by CPS America, maker of North America's number one three phase string inverter. With over 10 gigawatts shipped in the U.S. the CPS product lineup includes string inverters ranging from 25 kilowatts to 350 kilowatts. Their flagship inverter, the CPS 350 kilowatts, is designed to work with solar plants ranging from 2 megawatts to 2 gigawatts. CPS is the world's most bankable inverter brand and is America's number one choice for solar plants. Now offering solutions for commercial utility ESS and balance of system requirements. Go to chintpowersystems.com or call 855-584-7168 to find out more.