What Should We Do with Biogas?

Dan Andersen discusses the management of biogas, particularly methane from manure, and its impacts on greenhouse gas emissions. 

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Dan Andersen: 0:06

Hello, and welcome to Talkin' Crap, a podcast by Iowa State University Extension and Outreach. This institution is an equal opportunity provider. For the full non-discrimination statement or accommodation inquiries, go to www.extension.iastate.edu/legal. In this podcast, we discuss insights into the science technology and best practices surrounding manure management. Our objectives are to build awareness about the challenges farmers and the broader agricultural industry face around manure and to demonstrate solutions and areas of innovation. Hello, and welcome back for another episode of Talkin' Crap. Today we're talking what should we do with biogas? So let's talk about gas, not the kind we joke about in the shop. Well, maybe a little bit, but the kind that's becoming one of the most talked about pieces of agriculture's role in climate - biogas. Because right now, there's a big question sitting in front of farmers, engineers, policymakers, and really anyone paying attention to manure management. If we capture methane, what should we actually do with it? We can burn it off and call it greenhouse gas wind, right? Because it's not methane that was emitted to the atmosphere. Or do we turn it into electricity and compete with maybe some of the other electricity sources that are green, wind, solar, maybe even nuclear, or do we upgrade it into renewable natural gas and send it down a pipeline so some user somewhere can make heat or process energy or whatever they need? And here's the thing, this isn't really a technical discussion anymore. It's a policy decision. It's a market decision, and depending on how you look at it, it might be even a temporary decision, because policy is subject to change. So today we're going to try and unpack this a little bit, talking about some of what we've seen in the United States, in Iowa, and then I'm going to draw a little bit on my experience of a recent trip to Denmark to understand how their industry has been developing. But before we get too far into digesters and pipelines, I want to zoom out for just a minute, because when we talk about methane from livestock, it's easy to feel like agriculture is sitting at the center of the climate conversation. But if you actually look at where greenhouse gas emissions come from, especially in the US, most of it isn't agriculture. It's electricity, it's transportation, that's really the bulk of where all emissions come from. In greenhouse gas emissions, about 10% of all the emissions are actually agriculture. 90% is us using energy or fuel to get around, right? So when we talk about it, I know oftentimes it feels like ag is the bullseye. It is really a small piece of that pie. But with that said, agriculture and livestock in particular, they do contribute, and methane emissions from manure or enteric fermentation are a big part of that. But it really isn't the whole story, right? And you might say, if ag isn't the biggest source, why is there so much focus on methane right now? And part of that answer is, I think, pretty practical. We actually know some techniques to deal with it. We haven't found a way to make them cost affordable, or the thing you need to do on your farm to to make a living, to be viable, to be green. But we've had science behind this for quite a while that shows us some of the techniques we can use. And one of the most effective that we've seen is we can capture that methane, we can burn it, and we can use it right? And I think part of that is we like making a product, energy, electricity, and it feels like we're doing something more. We're taking advantage of our manure resource and getting even more out of it than we would when we just think about fertilizer. But, and I think that's great, and I think that's important, but I think the other part of it is timing. Methane is a powerful greenhouse gas, especially over short timeframes. So when we think about maybe what people have said for the 100 year global warming potential, or how much heat capture potential does it have, methane is about 25 times more potent. And if you would go with shorter life spans, methane is important, becomes even bigger. So if you can reduce methane today, you can have a relatively fast impact on warming. Basically, is all the warming it causes is up front, and then it breaks down into CO2 and acts just like a CO2 molecule. And so in a lot of ways, it's one of the levers we can pull right now that maybe will move the needle quickly. And maybe, if we're being honest, it's also because some of the other sectors are harder, or we think maybe slower, to change. While we see some people adapting electric vehicles, I haven't seen much change, really, in the vehicle fleet, in the US. We've maybe seen some changes in fuel economy, maybe a bit of electrification, but it's a hard, long term endeavor, and we're looking for something that maybe can move the needle right now to help buy us the time as we develop the what's next in transportation fuels? Is it a more renewable fuel? Is it electrification, what have you. I don't think we found that we're going to do this, and I think there's some hope that, well, agriculture could adapt and buy us some time, and whether that's right or wrong is above my outlook on this. I mean, I think about how does that impact us, and what decisions do we get to make? Because that's a policy, and while we overlap with the science and the engineering about what we might distribute, I think that's a policy decision, and it sets how we respond to it, and that's that's the perspective I want to come from today. So today, we're going to dig into what those options are for what we can do with natural gas, why or do with bio gas? Why renewable natural gas seems to be winning right now, and what that tells us about where manure management or anaerobic digestion is headed, especially here in Iowa. So what I'm going to talk about today comes from some work that Luke Soko, my graduate student, recently defended, working towards his PhD. So all he's got left is the walking basically. place we wanted to start was where greenhouse gas emissions actually come from. And I think as we set this stage, I mentioned 10% of emissions in the US are agriculture and 90% are related to energy or transportation fuels. So we're a small piece of that pie, and even more so when we think about actually the manure portion of it, we're 3 to 4% of all the US greenhouse gas emissions. So manure is extremely, an extremely small portion of that total picture. But we have a role to play, and I think the role we get to play is maybe outsized compared to our emissions, because even though we're not the primary driver, and we're actually a really small slice of the problem, not the whole pie, people dream about taking advantage of these in terms of how it might shape agriculture of the future, or it might even go into are there other things we can add to the digester, crop residues, some of our bio processing waste materials that we generate, or just other opportunities with food waste that might make agriculture, and specifically digesters related to being built around manure, have some opportunities beyond just the farm, and what could that do for the rural economy? And I think some of those are challenging, but they can be done, and we've seen some models of how we get there. So one of the things that I really wanted to address and make clear as we get started here is we know ag isn't the big emitter, and we know that manure is an extremely small portion of that, even a small portion of ag. So why is there so much focus on methane? And it's really that short term climate forcing. People are recognizing that it's us potent greenhouse gas, and maybe there's opportunities in the near term to really focus on that portion of it, to buy ourselves some time as we figure out good solutions for everything else. And like I've mentioned, that's a policy decision. I don't know what we do with it, but I do know that if the opportunities are given to us, whether through policy incentives, we should be strategically positioning ourselves to take the long run, right? Because sometimes ag policy can change on a whim, sometimes it's really steady and stable, but this is one where maybe some of our other industries have to look to us to help out in the near term while they figure out their solution, and that presents some opportunities, even if it does make us feel sometimes like we're in the crosshairs, and why are we being the one that's focused on so much. So let's bring this actually, to some of the options on a specific farm. And while there's many ways to tackle maybe some of the emissions, or especially methane emissions from manure, today, we're really going to focus in on sort of that digestion issue. And when we think about what producers or farmers with livestock can actually do to manage some of their methane emissions, anaerobic digestion systems are one of popular options that we've seen to really try and dive in. And we've seen a couple things, right? We could be putting impermeable covers to just capture them emissions that would naturally be generated and then hopefully do something with that gas. Or we could be going to heated and heated and mixed anaerobic digesters to try and make more methane that we can capture than we would otherwise do with sort of those natural and just covered systems. So I think one of the things I wanted to talk about is, sort of, how do you decide what kind of digester or a system you wanted to build? So let's focus in on sort of that, should I be covering a lagoon or a manure storage, or should I be building a digester? And the answer is, always, it depends. What's your situation, what sort of outlay we have, what sort of farm sizes we have, but especially on swine farms, we've seen a lot of interest in covered manure storages for a couple reasons. One, the manure storage already exists, so it helps lower some of that initial upfront investment cost, because all we have to do is put a plastic liner above that manure storage and we'll start catching the gas from now. There's some drawbacks from this. If I wanted nice, uniform gas production throughout the year, definitely not a covered lagoon, right? Because a covered lagoon is sort of subject to whatever the weather conditions are. So when it's warm, the microbes in that manure will be more active. When it's cold, they might be less active. Or if we freeze, maybe not active at all. Right? So methane production is really seasonal, and if you think about what that means, well, if I'm going to flare it. My flare might run some of the time and not other parts of the time if I'm going to generate electricity, well, sometimes I'll have gas to run through that generator. Sometimes I won't. So if we're thinking about this as part of our energy system, there's opportunities, but a lot of our gas will be in the summer, and we probably need more heat or process energy for heating our homes in the winter, and those don't always align. That isn't to say it's a bad thing if we have gas storage possibilities in the US pipeline or grid system, maybe that can work for us just fine. In general, lagoons are more popular as a manure management system. As we move south, I tend to think of I-80 as sort of the lagoon line. When you move above I-80, it tends to be colder. Maybe they aren't quite as effective at breaking down materials, and we don't see as many of them. So as we go south, especially south of Iowa, that is a bigger option. Here in Iowa, they haven't been as popular, right? We're in that deep pit model for swine barns and even most of our dairy farms, while they might have out of barn manure storages, I tend to think of them more as earthen holding ponds, slurry storage of some type, rather than a true lagoon where we're trying to releave some residual manure in there after we pump out as an inoculum to help keep microbial activity higher, or keep things functioning at a higher level. Anaerobic digesters have tended to be more popular as we've moved north, and I think that's what we see a lot of in maybe Wisconsin, New York and even some of our Iowa farms, especially the newer dairy farms that we've been seeing implementation on, have went that digester route. A big part of that is probably what sort of manure storage do we have? If you're holding manure in a lagoon for a year, even in Iowa, you might expect to get somewhere around 50% of the gas production potential out of that manure. On the other hand, if we start pumping twice a year like a typical dairy farm in Iowa does, you might think, Well, I'm only going to get 35, 40% of the gas production potential, whereas if I put in a digester, I might be 70, 75, or even 80% of that gas production potential. So you're really playing this game of, how do I compare minimizing cost just covering a storage if it exists compared to having to put in a digester and getting more gas. And part of that is, how stable are the carbon policies that are driving these decisions? If they're short term, we might feel that we have to make decisions that pay back our capital investment more quickly. If we feel like there's a lot of stability in those decisions, we might feel like we have putting more capital expenditures, putting more investment in to make sure we have the best system we can is ideal, right? And we'll keep it lasting for longer periods of time. But to me, policy decisions, and especially the stability of policy decisions, are really key in sort of driving which direction we pick and head. And I think we've had some strong policy decisions to support this recently, right? There's been that the RIN program, which we've mentioned before, that renewable identification number, and basically it said there's different RIN types based on expected greenhouse gas mitigation related to generating that type of fuel. And it sent a strong signal that been manure digestion could be successful. Now the challenge is that was sort of a short term policy. We don't have a really great long term outlook of how is that policy going to change, what other fuels might be coming into the marketplace to compete. So it doesn't always send a long term signal. It's been a how do we respond in the short term? Similarly, California and a few of the other states, Washington, Oregon, their low carbon fuel standards have been really key in driving some of the implementation we've seen. But again, they haven't really set long term stability signals about what stable prices might look like. They've said we recognize that prices now might be quite high. We expect them to come down as new technologies come online, new technologies are developed, rather than sending that stable system where we know that if we were designing for a 10 year life, we'll still have the price we anticipated today based on what today's current price is, right? And I think we do hope costs come down, and we hope that by seeing increased implementation, we can see some of those prices come down. But if I jump in the market today and I say my cost to make a unit of gas is X, if that price in the future would fall below X, all of a sudden, I'm not profitable if I don't have my equipment, my system, paid back in that time. I'm I'm sitting on the outside looking in and saying, Man, I wish I didn't do this. And I think that's sort of the challenge, right? Is, how does that price come down, and am I going to be able to stay below it for long periods of time? And I want to contrast this a little bit to what I saw in Denmark, and one of the policy decisions I saw there was they had actually offered a set price for 20 years. So if you got in and you said, Well, my price to make a unit of renewable natural gas is below this price, you were locked in, right? You're going to feel like you have that stability, and it really has caused them to pick and develop infrastructure based on that 20 year design life, rather than a start and stop model. And I think that was one of the key takeaways, for me, is that it's not just having policy that supports the implementation, it's the longevity of that policy. How do we feel like it's going to be there and protect this throughout the lifetime of the project, not just the short term. And before that, I mean, I recognize the importance of that, but my mode of response, and I think the mode of response of a lot of investment in the US, had been thinking about, how do we limit initial capital expenditures, rather than a coordinated design to make sure that these things will be in place for the long term and can be successful for the long term. The other thing that that has led to that I was really interested in seeing and hadn't anticipated to the scale it was, was sort of just how big their plants are, and they had got beyond thinking about the farm scale to really more towards large digesters that are community or collaborative among many farms. And I'm not saying that's right or wrong, but generally, there is a pretty steep economy of scale with many of these systems. The bigger we get, the lower cost unit of gas production is. So thinking about, how do we scale, or how do we help make this a more cost, affordable technology for many, many people to participate in was interesting. It gave us a different perspective. And I think the US model has often been, how do I think about making it work on my farm, or does it work on my farm? And this says that that can work, right? We can find the biggest farms and be successful. But this is us potential model for how to open it up for more people to participate. All right. So one of the things that Luke really was focused on, for me was a core decision, what do we do with the gas that we generate, and why? All right? And there's really been historically three options for this. The first one is, just capture it, flare it and turn it into CO2, right? And there we're really focused on greenhouse gas especially methane mitigation at that farm. We're taking a potent greenhouse gas, methane, we're turning it into CO2. We're still releasing it to the atmosphere. We're not really generating another product. It's just for mitigation purposes. And I think there's been policy that can help support that, mostly on the private carbon credit market, where the going rate for CO2 mitigation might be 30 to $40 per ton of CO2 mitigated. If we're really mitigating it, we have a lot of certainty that is not going to the environment, right? We can measure how effective it was with a flow meter and how often we're flaring, or the effectiveness of that. It hasn't been an extremely popular option, all right, and I think part of that is farmers feel like they're feeding the world. They're generating useful products, and this one is more of a treatment, right? It's not generating anything that's usable. It's a mitigation technique and and there's not necessarily anything wrong with that, right? We see other places where we do that wastewater treatment of human municipal sludge, for example, right? It's not trying to make a useful product. It's trying to minimize negative impacts on the environment. But to me, flaring is sort of that option. The second option is making electricity. And as we look at the early 2000s and the first time I really got interested in anaerobic digestion, we were in sort of this electricity boom, right? People at that time were looking for, how do we decarbonize the electric grid, and what are some of the options? And you saw huge uptake in wind power in Iowa that has lasted 20 years, and we've seen development of solar panels and biogas played a role in that. And I think one of the things that I took away from that is generally electricity can be made more cheaply with wind turbines and solar powers per kilowatt hour than it could be from anaerobic digestion systems. Now, with that said, there's multiple ways to think about this, right? We've mentioned with flaring, it was sort of a mitigation technique, and if you think about generating electricity as both generating usable product and mitigating maybe some of those greenhouse gas effects, well, manure systems still might win right on per dollar per ton of CO2 mitigated. They're not only mitigating that energy generation cost of carbon, but they're also helping mitigate some of those farm costs of carbon, right where we have this emission source, and we need to think about something to do with it, so as a society that still might be more effective than solar energy actually cost per unit reduction of carbon, but we definitely won't make the cheapest kilowatt hour, at least with the technologies that we've seen developed thus far and the improvement in solar panels. And that sort of led us towards this modern day incentive structure that we've seen, where most of the anaerobic digestion projects are focused on upgrading to renewable natural gas. And the value proposition there was, well, we're not competing with electricity, we're competing with other transportation fuels, gasoline, diesel and methane, burns clean and renewable natural gas doesn't generate new carbon to the atmosphere, right? So all those were sort of value propositions of we're focused on the same gas, methane, and how do we mitigate it? And then we've came up with various different pathways for use of that thing. And I think when I look at it, if I wanted, if I was in agriculture and I said, we're trying to decarbonize, I'd look at it as what's the dollar spent per ton of CO2e or equivalents of carbon dioxide emissions mitigated. And I think to me, electricity or flaring tend to be the lowest cost option. Relatively similar. Small differences in your farm size might impact that, but relatively slow differences, small differences. Upgrading to renewable natural gas is the most expensive option. So if we're trying to mitigate emissions from agriculture, we probably wouldn't move that direction, at least from what I've seen and what Luke sort of did for an analysis for me. On the other hand, if we're trying to think about what's our role in helping other industries decarbonize, that changes a little bit, right? If we're we're flaring, we're saying we have no responsibility beyond our emissions, and we're focused on that. If we're making electricity currently, if we're replacing natural gas or our coal, we're mitigating some emissions. If we think about a world where we move even more towards wind and solar, until that grid is green, we'll only be mitigating our emissions, but we'll still be generating a usable electricity product. And maybe there's a role to play in there, right? Maybe solar and wind are susceptible in times when the sun isn't shining and the wind isn't blowing, and the renewable natural gas we're making could help with low leveling and mitigation. I think the challenge I'd run into on that thought is, well, I need to save it and burn it when I really need it. So I'm probably not saving it as dirty biogas, right, or biogas that has CO2 and trace impurities in it to burn for electricity. I probably need to turn it into methane and have a storage system for it, which really takes us to generating renewable natural gas. And sort of, as I look about why we've done natural gas, we use a fair amount of it for lots of industrial applications, for for things that need intensive heat or for low leveling for electricity, right when electricity demand peaks, and solar and wind can't meet it because it's beyond what we had designed capacity for. Well, we turn on renewable natural gas electricity generation, and we can sort of have that topping load, and there's a lot of opportunity there. So when I think about like, maybe renewable natural gas to electricity systems are two to three times more expensive per kilowatt hour than solar or wind or the current grid system that we have right now. They maybe have a role to play, but maybe that topping energy is is a little bit more valuable. With renewable natural gas, if you look at sort of the US baseline price, we're probably six to eight times more expensive generating renewable natural gas than the grid price right now. On the other hand, if we believe that those industries need a decarbonization pathway, we might be it right? I mean, there's very few options for high energy density, ways to generate industrial heat other than natural gas. Maybe some of those industries could look towards electrification options, but many of them haven't found available opportunities that are quite as plug and play as renewable natural gas. All right, so we've talked a little bit about some of the pros and cons, and flaring is sort of low tech. It really is about decarbonizing agriculture, and it's mostly a greenhouse gas mitigation play. There's no real revenue source outside limited credits when we thought about generating electricity, we said, Well, that was historically common in the early 2000s but it has to compete with other green electricity options, namely solar and wind. Grid connections are relatively easily, easy, but this has led to some some pricing challenges and and maybe harder to see a direction forward. enewable natural gas, it's the most expensive of all the options we need to upgrade that gas get injected in the pipeline, but it's really displacing fossil natural gas, and we've seen strong policy incentives that Renewable Fuel Standard, LCFS, is adopted at the state level that have really helped support that. So both electricity and renewable natural gas are about decarbonizing, but maybe gas has longer term value because it's decarbonizing industries that are much harder to decarbonize than using straight electricity generated from other sources. So it's looking for that potential or that value added location to maybe make that difference for us. And that's led to why natural gas is really being selected right now, right so right now, RNG systems are really dominating, and that's been driven by those credits where we've seen high push towards adoption, and especially in the opportunity to decarbonize some of our transportation fleet, especially related to larger commercial vehicles. I think one of the things that people look at this and say, well, there's some some good things we're taking advantage of, is there's a large pipeline infrastructure already available into the in the US that moves this methane around, and we've invested in it. This is a way to keep using that being green, even into the future. All right, so what I wanted to finish with was maybe some of the bigger takeaways from what we've learned from trying to do this analysis and how to push manure management in the future. So I think in order to be economically viable, one of the things we've seen is, while we all want to get to small scale to help support some of those smaller farms, it's hard, and one of the things we might have to think about and react to with some of the anaerobic digestion systems is it might be about community systems, or thinking about how to make these practical, to work with farms of all sizes, but really either sharing upgrading facilities, sharing injection points, sharing the actual So all right, I think I've rambled about enough for you all, and I wanted to take a moment to wrap this up and bring digestion system, and thinking about a bit as a more it around to what I'm hoping we're all taking away from this. So if there's one thing I hope you got from today, it's that centralized system. We also are going to have to start thinking the question isn't, can we capture methane? We certainly can. We've been doing it, and we get better at it every year. The about, what are the opportunities, and when should real question is, what should we be doing next? And how do we we be integrating feedstocks beyond just livestock manures. have thoughtful policy to incentivize long term, the direction we're going to try and head forward. So right now, Manures are a great first step, and they've made a lot of sense renewable natural gas is clearly winning, not because it's the only option, and maybe not even because it's the best, depending to focus on, because we get that methane control from the on what our goal is, option in terms of pure engineering sense, emissions they already would have had. So it's really a but because the policy and market structure have lined up to reward it, right? And that's because we wanted to decarbonize mitigation approach more so than I'm trying to generate transportation fuels. If our goal is to reduce methane emissions from farms, flaring or electricity generation will electricity or other energy. And I think as we look towards maybe always have a role. It works. It's more simple. It's proven, and in some cases it might be the most practical first step. some of those other opportunities, food waste, With electricity it does look like we're fighting a uphill bioprocessing waste, we have to be thoughtful about what it does battle. Wind and solar have both demonstrated that they tend to be lower cost generally than anaerobic digestion. Certainly, to farms nutrient budgets or balances, and also about how there's cases where digesters can compete with them, but it's hard to make the numbers work unless there's something much leakage we have coming from the digester or from gas changes. And we can think about decarbonizing transportation industry because of electric vehicles and the demand for storage. But there are some opportunities there, and electricity will generate quickly, and especially generate managing those leakage rates really carefully will be quickly in places where we want to save agricultural landscapes for production of food, fuel and fiber. And renewable natural gas critical to long term success of those strategies. But from a right now is filling that gap. We've got sectors, especially in transportation or heavy transportation, that are hard to manure perspective, and sort of what excites me about what's decarbonize, and frankly, right now we're unsure about the happening and why it matters is we think about maybe some of the potential of electrification of those industries, so generating pipeline quality gas with low carbon intensity scores fits community digesters that might make nutrient management sort of really well in that space, both now and long term. It isn't being driven by agriculture. It's market forces beyond us the bottleneck in this process, because we're going to haul from that are really shaping the discussion and the decisions, but we're left to determine our role in this game of renewable a location to a centralized facility, and then most Iowa energy that they're playing and I think we want to be a part of the discussion. We want to be at the table to make sure that our farmers value their manure. We want to get those nutrients back agricultural system is moving in the direction we all want because of the policy that is being used to cause some of to them. How do we do it? Is it a hauling system? Is it a these changes. So as always, thanks for joining us on Talkin' Crap, and we look separation system? And working through those nuances of what's forward to seeing you next time. Thank you for joining this installment of Talkin' Crap. Be sure to take a look at the show going to be best and be most feasible really positions us notes on our website for links and materials mentioned in the much more strongly to be successful. episode. For more information, or to get in touch, go to our website, www.extension.iastate.edu/immag. If you found what you heard today useful, or it made you think, we hope you subscribe to the show on your podcast app of choice, Signing off from a job that sometimes smells, but never stinks. Keep on talking crap.