Biogas: The Good, the Bad, and the Sludgy – Episode 225 of Local Energy Rules

Brenda Platt:
In Maryland there was a dairy cow farm site. They were composting the dairy cow manure and the site said, oh, we can’t afford to keep going and composting it, so we’re going to stop composting. So they started land applying the manure, and within a few weeks they were getting complaints. Oh, we’d like you to start composting it again. So just to kind of give you an indication that the lagoons and the raw manure has a lot of odor, has a lot of runoff, watershed issues, but when you produce a mature product from it, that is an earthy smelling product that’s stable. I mean, it’s night and day

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John Farrell:
Often overlooked in a renewable energy world focused on wind and solar power, anaerobic digestion processes organic material in the absence of oxygen to produce biogas, which can be burned for heat or electricity. Also produced in the process is digestate, and, if it’s high quality, it can be used as a soil amendment or as an input to composting. Joining me in October, 2024, my colleague Brenda Platt, director of ILSR’s Composting for Community Initiative, warns of ‘garbage in garbage out’ with anaerobic digestion, and we discuss the benefits of keeping digestion local. I’m John Farrell, director of the Energy Democracy Initiative at the Institute for Local Self-Reliance, and this is Local Energy Rules, a podcast about monopoly power, energy, democracy, and how communities can take charge to transform the energy system. Brenda, welcome to Local Energy Rules.

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Brenda Platt:
Hey John, good to be with you.

John Farrell:
So I ask all my guests, and even though I probably know a little bit more about you than other guests, I would love to just ask you, how did you get into this work? Maybe even, how did you get to ILSR at first, although you’ve been here for a while, and what led you toward this focus on food systems and composting as a crucial piece of our work on local self-reliance?

Brenda Platt:
Well, funnily enough, I think I actually got my job at ILSR because I did a paper my senior year of mechanical engineering school on biogas, and Neil Seldman, one of the co-founders who hired me, knew about that paper. So I do think my gateway to ILSR was anaerobic digestion. I did it in 1985, I’m actually holding up a copy of it now, and it’s called Waste to Resources: Biogas from Animal Human and Agricultural Waste, and it was for a resource management conservation class I took.

John Farrell:
That’s incredible. Well, this is a great opportunity then. You’ve got the paper in front of you if you need to reference it. Can you just give our listeners a brief explanation of what anaerobic digestion is, what materials go in and what comes out of this process?

Brenda Platt:
Yeah, I just want to say I hadn’t looked at this paper in almost 40 years until this morning, but my definition of anaerobic digestion in the process I think is still spot on. So in the anaerobic digestion process, bacteria decompose organic material in the absence of oxygen. That’s what makes it anaerobic – the absence of oxygen, producing biogas, which consists of 50 to 70% methane with most of the remainder carbon dioxide. Anaerobic digestion involves a number of different bacteria and the exact, this is probably what has changed, the exact biochemical processes and relationships are not yet fully understood. I think that has changed in the last 40 years. But the basic reactions, however, are as follows, decomposition of plant matter into usable size molecules, and then conversion of that decomposed matter to organic acids and third conversion of those acids to methane by meth bacteria. So the bacteria that thrive in anaerobic digestion are those that thrive in anaerobic conditions, meaning lack of oxygen, and that’s very different from composting, which is my current specialty. Those bacteria and fungi thrive in the presence of oxygen. Composting needs oxygen and happens in the presence of oxygen.

John Farrell:
So in addition to the methane gas and the carbon dioxide that comes out of a digester. Brenda, what else do you get? So there’s still some physical material left as well that comes out of your digester, right?

Brenda Platt:
Yeah, exactly. That’s called the digestate. And that also results from the process and that has to be managed and dealt with and it’s often used as a soil amendment, but there’s very little regulations and standards for the digestate and health use. So when we get into some of the pros and cons of anaerobic digestion, we can talk about that.

John Farrell:
Sounds great. So I guess there’s a couple of things to think about here. One is that when you produce methane from a digester, you can then burn it. That’s essentially the major chemical in natural gas that we often use for generating electricity. Or you could use it for generating heat by burning it. So you have an output that comes from a renewable resource, which could be like food or agricultural waste, and then you’re producing, you can produce electricity from it. So in some cases people talk about this as renewable electricity. So that’s kind of my expertise and my experience with it is in other countries when they were promoting the development of renewable electricity technologies and in the early years there was nothing that had sort of a big competitive advantage like solar energy or wind energy do. Then they were kind of exploring a lot of things and digesters were one of those things.
But I’m a little less familiar with the materials that go into this other than the fact that because there are, you need materials to do digestion that makes it more complicated than things like solar and wind where your resource is basically everywhere and free and doesn’t involve having to stick on a truck and move around. So could we talk a little bit about these inputs, and let’s start with food waste. I know that’s your area of expertise. Is there some reason that we shouldn’t be using digesters to produce methane and then burning it? What implications might it have to use digesters for food waste for the economy, for the climate, for other uses of food waste?

Brenda Platt:
Both anaerobic digestion and composting are biological processes, and generally the environmental community is in favor of these technologies to get energy out of the materials. So whereas if you’re actually burning garbage in incinerators, there’s huge movements around the world and in the US fighting the proliferation of garbage incinerators. So it’s really actually that battle over many decades to fight trash incinerators – named by the industry, I think it’s a propaganda name to call them resource recovery facilities or to call them waste to energy because as we know, those facilities are just burning the embodied energy that is in the material. So they’re not really producing energy, they’re actually just getting the BTU value out, whereas anaerobic digestion is really harnessing the bacteria and natural processes to produce that biogas.
However, with any facility, garbage in, garbage out. And so the main concern with taking food waste or mixed materials into a facility is if you’re getting food packaging or you’re getting chemical contaminants like PFAS and then the digestate and even the biogas is contaminated, then you’re going to apply it to farmland?
So we’re seeing a lot of corporate concentration in this field. I’ll talk a little bit about that. But in terms of if we look at the anaerobic digestion facilities around the country, many of them are actually at wastewater treatment plants or they’re taking sewage sludge or human biosolids as they’re called. And there was a study done in 2017 that almost 1300 anaerobic digestion facilities that are wastewater treatment plants were creating biogas, but only 67% were actually using their biogas. Most of them were flaring them off. And when you think about what’s coming out of those, the digestate, think about what a wastewater treatment plant is, right? It’s about cleaning up the water so that we can drink it. So where do all the contaminants in the water go? Well into the sewage sludge that’s left over. So now if you’re putting those biosolids, that sewage sludge into an AD facility, I mean, as we know, matter is neither created nor destroyed.
So those heavy metals are going somewhere, those chemicals are going somewhere. So that’s a big concern when we have wastewater treatment plants that are dealing with a lot of contaminants already and food waste by and large wasted food, I like to say, rather than food waste because waste is a verb, not a noun, we like to say, but wasted food can generally be fairly clean feedstock. But when you begin to mix it with biosolids or sewage sludge, then it ends up becoming more contaminated. So I’m more in favor of keeping wasted food separate from sewage sludge and treating it separately and locally. So just like with composting anaerobic digestion, facilities can come in all sizes, and some of them can be small scale and handle materials on site.
There’s a couple of companies that we know of. One is called Chomp, and one of the sites where they have their anaerobic digestion system is at a tofu factory. And then the energy is being used to power that tofu factory. I mean, that’s like local self-reliance in action.
They had another site at Bainbridge Island at a restaurant where the food waste coming from the restaurant was going into this digester, which is the size of a shipping container. So it’s really onsite and small scale. And then the digestate was going into the garden as a soil amendment and the biogas was being used for the restaurant. So again, another model of local self-reliance, and you can control the feedstocks. So if you know what’s going in, what’s going out, you’re more likely to want to put it on your garden or your farm. So again, all sizes. One of the things that we’re seeing is the corporate concentration I mentioned, there’s a company called Vanguard Renewable, it’s Massachusetts based, and they were bought out a few years ago by BlackRock.
Now, BlackRock was a company that was in the 2022 Corporate Hall of Shame. They’re the largest asset holder in the world. I think their assets make up 33% of global emissions, greenhouse gas emissions. I mean, they’re one of the largest financiers of plastics production and single use products. This is the kind of corporate concentration that’s taking place in the anaerobic digestion industry. And they have very aggressive plans to build out like a hundred new AD sites with $2 billion that they’re investing. And I think what’s concerning about this is not only who’s owning the systems, but that for food waste, a lot of the message is, oh, we’ll build a large scale site, and they’re telling supermarkets and other food generators, large scale generators who generate wasted food. Oh, don’t worry. You don’t need to separate your packaged goods from your clean produce waste because we’ll handle it all. And we’ll put what’s called a depackaging system in front of our AD. And these depackagers are these physical systems that pull apart the materials or shred them. And you can imagine that what you end up with is more microplastics, more chemical and physical contaminants in the digestate. So when you go to large scale, there’s a lot of issues that arise. It’s just who owns the system? Where’s the material coming from? Are there clean feedstocks? Where’s the end product? The digest going? So it raises all kinds of issues.

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John Farrell:
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John Farrell:
This is really interesting because one of the things that sank the widespread adoption of digesters in terms of a renewable electricity focusing on the electricity system was just that, as you have alluded to with the feedstocks, it was complicated to figure out where are you going to get your feedstock from? What about issues of contamination if it’s not consistent, if the feedstock isn’t consistent, even its moisture level, for example, can affect how well the digestion process works. So these are very unique systems sort of designed for each particular place that they’re at and compared to something like solar where you can throw up the same exact panel and inverter on any roof anywhere, and it works exactly the same, right? It really lent itself to kind of economies of scale and manufacturing and an installation that made it cheaper. So it’s interesting to think about here how there’s still an upside to digesters if they’re operating at the right scale, if the digestate that they’re producing is not contaminated because they’re careful about it. But then it definitely raises some questions for me. I guess maybe without trying to answer the question, it raises some interesting questions about how do you design incentives or anaerobic digestion on the renewably generated electricity side of things that don’t disrespect the notion that we also want other outputs from that system, not just the electricity, to be usable and clean and efficient as well.

Brenda Platt:
Policy is so critical in this space. I mean, on the one side, on the positive side, we have a lot of states, particularly New England, that have adopted policies that require large generators of wasted food to do something with that food. If you generate two tons a week of wasted food, you cannot dispose of it. You have to do something with it. And by the way, two tons a week is about the average of what a typical grocery store generates. So that’s why that threshold was written into those laws. So Massachusetts, Vermont, Rhode Island, Connecticut, I think New York state has a policy. Maryland is a more recent policy, a state that has instituted that. But the downside of those policies is that it’s actually paved the way for large size industrial sites and for these depackaging systems to be built in front of the systems.
So it encourages large scale sites and marketing to supermarkets. So just send everything to us, we’ll handle it. And I think that the unintended consequences is that the opportunities for building out decentralized distributed infrastructure for wasted food, that by the way also includes food rescue to feed people. I mean, we need cold storage to rescue food at all levels, from farm scale to schools, to food banks, and that everybody understands that if you could build cold storage, it’s got to be distributed. Nobody’s saying, oh, a state like Maryland, you need one $30 million cold storage facility to rescue food. No, of course not. We need refrigeration systems everywhere and think about the investment that’s needed for rescuing food to feed people, the benefits to people who need that food, and the food insecure communities. But in the end, what we have now are state policies that are just encouraging large industrial sites that are not rooted in community and not really serving community. And I think what I see is going to happen, and what I’m concerned about is that what’s coming out of these facilities will be highly contaminated and give a bad name for anaerobic digestion of all sizes. We’ll give a bad name to composting sites of all sizes because of the contamination. So we really do need policies that are oriented towards funding for distributed and small scale sites and that drive the market towards high quality soil amendments.

John Farrell:
Let’s talk a little bit about the other place that we’re seeing digesters be proposed, and then I do want to come back and talk about what are some of the better ways to do this. You’ve kind of alluded to this already, but I want to, especially with food waste. Sure. Composting might come up in this conversation, but when we’re talking about animal waste, like how, or pig manure for example, we have a lot of very large corporate feedlots, for example, and there’s been an increasing interest for them of like, oh, well, if we just use digesters, it helps to sort of excuse this business model that is otherwise fairly destructive, that obviously it has a lot of other implications about use of antibiotics and animals instead of humans because of the way that they concentrate the living conditions for those animals. You have these very large sewage lagoons they call them, that have impacts on nearby communities in terms of persistent smell, and of course the risk that during extreme weather events, as we are having increasingly that those lagoons will then burst and contaminate waterways. So people are saying, oh, well if we use anaerobic digesters when the digestate comes out the other side at least it’s no longer infectious. Like the bacteria that’s in it have been sort of neutralized by the digestion process and we get some electricity production out of it or some heat production out of it. What’s your take on how we should be thinking about digesters when it comes to animal waste?

Brenda Platt:
Well, digesters generally can handle more liquid materials. Feedstocks. Feedstocks are the materials going into a system. So compost sites need to balance carbon and nitrogen. Think of carbon as your more woody materials, your yard trimmings, your fall leaves, whereas the digester really wants materials higher in nitrogen and more liquidy. So digestion really does lend itself to animal manure. And I’ll just point out when I did the paper back in 1985, one of the things that I found is that biogas digesters really had proliferated in countries like China and India. I mean, China had something like 7 million digesters mostly on small scale farms handling animal manure. And India had 430,000, I don’t know what the numbers are today, but the point being that anaerobic digestion is implemented in these countries that are very small scale at small scale farms, sure they can work at large scale farms as well, but I think there are more issues just with the antibiotics and whatnot.
And when it comes to the digestate, first of all, I mean digestate is an improvement over the lagoons you’re mentioning, which are horrible. But the digestate as a soil amendment, as I mentioned at the top of the podcast is there’s very little standards and parameters around using that as a soil amendment. Whereas with compost, there’s more and there are really big differences. In fact, the US Composting Council just released a brief called Compost and Digestate: Dispelling the Confusion, and we’ll put it in the show notes, but it does an excellent job of spelling out the difference between using compost, which is a mature product where the nitrogen in it is stable and can be released over time to plants, versus digestate, which is more readily available nitrogen. That’s just kind of a fertilizer that is more like a steroid if you will, that just gives to the plants and can run off into waterways.
So there’s more concerns with just using digestate, which is not a stable, mature product as compared to compost. The good news is anaerobic digestion can be combined with composting, and there are a number of sites that do that. It’s very popular in Europe to compost the digestate at the end of that process so that you’re actually producing compost. So I think a lot of agricultural farms that rely on livestock could be doing more anaerobic digestion on a small scale and producing the digestate and composting it. We had an example of, it wasn’t a digester, but in Maryland at a dairy cow farm site, they were composting the dairy cow manure and the site said, oh, we can’t afford to keep you on to compost it, so we’re going to stop composting. So they started land applying the manure, and within a few weeks they were getting complaints, oh, we’d like you to start composting it again. So just to give you an indication that the lagoons and the raw manure has a lot of odor, has a lot of runoff, watershed issues, but when you produce a mature product from it, that is an earthy smelling product that’s stable. I mean, it’s night and day.

John Farrell:
I’m super curious right now, this is neither here nor there, but I actually saw in the newspaper here in the Twin Cities, I had stepped outside like last week, and I got a whiff of manure on the air, and I live in South Minneapolis in the center of an urban area. And they had said that this time of year agricultural producers out in the exurbs are applying manure to their fields. And I just kept thinking to myself, why should I have to smell poop right now? There probably are ways to do this better. So it’s super interesting to hear about how this particular issue in Maryland and the fact that there are alternatives to having to let that smell cascade across an entire urban area.

Brenda Platt:
Yeah, a hundred percent. You don’t have to smell it.

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John Farrell:
We are going to take a short break when we come back, I ask Brenda about the hierarchy of uses for wasted food. We talk about trash incineration and about policies to adopt and to avoid, to promote the best management of food waste. You’re listening to a Local Energy Rules podcast with Brenda Platt, director of the Composting for Community Initiative at the Institute for Local Self-Reliance.

Hey, thanks for listening to Local Energy Rules. We’re so glad you’re here. If you like what you’ve heard, please help other folks find us by giving the show a rating and review on Apple Podcasts or Spotify, five stars. If you think we’ve earned it. As a bonus, I’ll gladly read your review aloud on the show if it includes an energy related joke or pun. Now, back to the program.

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John Farrell:
So I want to come back to the food waste question because one of the things that you started to allude to that’s really important in the consideration here is in the same way that we have this conversation about recycling versus burning trash. I think on the food waste side of things, you already mentioned recovering some food from grocery stores that’s still edible for people who are food insecure. Do you have a list of preferential uses, a food waste hierarchy perhaps, that would guide people to understanding what are actually better uses of food waste before we consider putting them in a system to generate electricity?

Brenda Platt:
Yeah, we do. We have a hierarchy, it’s called Hierarchy to Reduce Food Waste and Grow Community. And it’s a graphic, so it’s one page. It’s also available in many languages, Spanish and other languages. And we produced it because we wanted to highlight the importance of locally based solutions as a first priority over large sized industrial regional solutions.
One of the beauties of composting, and I will say with composting in particular one of the beauties is it can be as small as a worm bin in a classroom or a home composting bin in your backyard, but anaerobic digestion can be small scale too, the size of a shipping container and literally everything in between. So this hierarchy addresses issues of scale, but also includes community benefits. So we have to address this notion of garbage in garbage out. So if you’re composting in your backyard or your restaurant with a small-scale AD facility on your site, you’re not going to put contaminants in those systems because you’re going to be using the compost or the digestate coming out of there into your soils.
And so the larger you get, the less control you have over the system, sure, the more you’re diverting. But we can scale up small size systems in a distributed way so it can become the major way that we handle our wasted food. But this hierarchy kind of lays out, keep it small, keep it in your communities. The first priority, even before we’re recycling, is that we have prevent food waste. There’s a lot of food waste that we could prevent, rescue edible food to feed people and livestock if that’s the case. And then home compost, keep it in your community, promote on-farm handling of these materials. Then regional and large scale is the absolute last systems that we should be doing. And so we think this is a good guide for any decision maker in your community to be using.

John Farrell:
I really appreciate both the discussion of scale, but also sort of the prioritization because I think there is this sort of sticky feeling. And I think about in terms of Hennepin County where I live in Minnesota, which has had a zero waste commitment for many, many years, and there’s currently a lot of tense discussion happening between the advocacy community and the county over. They have done an admirable job in reducing waste, but they still operate a trash incinerator. And there is, I think this belief of like, well, if we shut down the incinerator, we’re just going to have to landfill stuff. We can’t go upstream to solve this problem that people are just going to keep producing trash. And I appreciate that they don’t have control over all of the components of that. But I think it is a really important lesson that there are places to go before we have the stuff that we’re thinking of trying to get rid of.

When you talk about grocery stores and that two tons a week of wasted food, what can they do upstream in terms of food rescue, for example, or to use that for local compost before they would end up sending it to a large scale digester, for example, where as you, there are these issues with contamination that could potentially be avoided if you’re doing it at a smaller scale or more locally, or if you’re simply just trying to reduce the amount. So we’ll have a link to the hierarchy in the show notes for folks who want to see that and dive in more.

Brenda Platt:
And I don’t know if Hennepin County’s incinerator is one of these with what’s called a put or pay contract, but a lot of trash incinerators in the country have these, what they’re called put or pay contracts. Let’s say an incinerator handles 300,000 tons a year. A county or local government will have to pay that fee for that tonnage, whether or not they reduce it or rescue the food or recycle. So it’s called put or pay, and that’s how they got the bonds issued to build these multi-hundred million dollar incinerators. So it’s a disincentive to actually reduce waste and recycle and compost as much as possible because you’ve got to feed the beast under these put or pay contracts. So incinerators are bad news for communities.

John Farrell:
I’ll link in our show notes to an ally group of ours, the Minnesota Environmental Justice Table, and some of their work. What’s interesting in this case is it’s not like a private company. The county owns the incinerator itself. It’s a publicly owned facility. So yes, there are probably some economic considerations here, but if they’re forcing themselves to take the trash, they’re forcing themselves to do it. So it’s a really interesting scenario that might be different from some of these other situations where you have third party ownership.

Brenda Platt:
And even in Connecticut, there were some publicly owned incinerators, but they forced the towns into put or pay contracts, so the cities and the municipalities and the towns had to do it. So again, I don’t know about Hennepin County, but

John Farrell:
Well, let’s talk about on the brighter side, what are policies, you’ve already referenced a couple of policies in New England that are meant to address wasted food. What are you seeing as some of the best policies that states or even cities could adopt that help to process wasted food more responsibly?

Brenda Platt:
Yeah, so requiring source separation of wasted food at the source, which is what that term implies, source separation means that you are going to separate non compostable or non recyclable materials at the source from contaminants. And enforcing those policies is really important. I think when there’s grant programs that are available at the state level, those grants should be prioritizing and not privileging large scale sites, but privileging sites that have good plans to keep the materials high quality and clean so that the inputs that in this case, almost all digested and compost ends up in the soil one way or another. So it’s really critical that we grow these markets in a responsible way.
There was in California, just to give an example, and I keep pointing to bad policy, and I know you’re asking me about good policy, but this is the lessons we can learn from some bad policy too. So in California was one of the first states that had grants under their greenhouse climate grant program, and I think they were giving out like 40 million a year to build facilities like compost sites and anaerobic digestion sites. But one of the criteria for that grant, you got more points and favorable rating and scoring if you diverted more food waste because if you diverted more wasted food, you avoided more methane emissions. But what that led to was that huge projects that were handling the most tonnage got the funding, and it was kind of a once in a lifetime opportunity in California to build out a diverse infrastructure. But what were they doing with their money? They were giving it to all big industrial sites and leaving behind farmers and community, community sites and schools and other great projects that could benefit from that money because the state wasn’t set up to give out a whole bunch of small grants. So we do need some policies that enable state government to give out money in the form of smaller grants to farmers set aside more money for farmers and community projects so that we’re not privileging large scale sites.

John Farrell:
I actually wonder if it is sort of a useful corollary was when ILSR was working, gosh, almost 20 years ago now on farmer owned ethanol plants. We worked on policy in the state of Minnesota, and one of the ways that we designed the incentive, it was an incentive program for producing ethanol that was, I think a few cents per gallon. I can’t remember exactly how it worked, but it was capped. So it was up to like 10 million gallons per year, which was about the scale of a cooperatively farmer cooperative farmer owned ethanol plant that would serve a small region where those farmers then are invested collectively. They are the supplier of the commodity, which in this case was corn to the ethanol plant and they were the owners of the plant. So we had that marriage in terms of scale between the size of the facility and the local ownership and the local focus. So I don’t know, just something to think about. I don’t know how you would dial that up in terms of making it work here, but I think your point about making sure that the incentives are structured in such a way to get you high quality output, or in this case to really support those local economic benefits of community ownership are really important.

Brenda Platt:
Yeah, I mean, I think invoking a model like that in this space would be an ideal thing to do and push for. We have a bill in Maryland that we’re supporting. It would create a nominal $2 per ton surcharge at landfills, incinerator on the waste coming in and create a grant program. And one of the things we spelled out in the bill is there’s going to be a carve out for farmers to build onsite AD and composting facilities. There’s a regulatory roadmap, but there’s no funding for them to build out those sites. And that we also favor projects in underserved communities, whether it’s rural or urban, and that have a plan in their proposals to produce soil amendments free of physical and chemical contamination. So there’s a lot of ways through funding mechanisms that you can, as they say, follow the money. So have the money fund the world in which we want to live in.

John Farrell:
I’m kind of curious about this idea about the usable output, whether it’s digestate or the compost. I think you kind of mentioned earlier that there are more standards for compost than there are for digestate. Are there any kinds of standards with all the different kinds of feedstocks? I’m kind of thinking to myself, I don’t know, maybe this is really complicated, but maybe it isn’t very complicated. Maybe when you talked about digestate having more readily available nitrogen that’s subject to runoff, maybe you simply say, well, if you’re going to sell, it has to be classed as a fertilizer instead of a soil amendment that is higher quality or something. Or maybe there’s attacks on it if it’s not up to a certain standard. Or is there testing, for example, for contaminants from chemicals or plastics or whatnot that would penalize the producers if they’re not doing a good job? I guess it seems like there needs to be more regulation and oversight if we want to successfully direct good uses of this in the right places.

Brenda Platt:
Yeah. Well, one thing I’ll just say is that there are federal standards for where you can use biosolids, which would include digestate if it’s coming from a wastewater treatment. So you can’t use biosolid digestate on organic farming, for instance. So there’s different classifications for that, but there’s still a lack of good standards at the state level between compost and digestate, and there’s a lot of confusion. The other thing to note is that compost can be used for a wider range of applications. For instance, one of the fastest growing markets for compost is in erosion control products. So think of green roofs or bioswales or something called compost socks where you low compost into these big tubes and they can be stacked up for riverbed restoration or for construction sites to prevent stormwater runoff. I mean, we’ve all seen those orange plastic SELT fences that don’t work.
So instead of that compost socks that act as berms, if you will. So sometimes those compost socks are designed for the water to flow through them into stormwater drains, and sometimes they’re designed to hold the water in and they’re very effective I, and so compost can be used for potting soils and bagged for home gardens and all this stuff. And digestate really can’t be, but there’s a lack of controls and standards around digestate. So I do think there’s more work that needs to be done, but be done in this sector of the creating markets for, it’s

John Farrell:
So interesting. Anything else in terms of the policy places that have good policies or other policies that ILSR recommends in terms of designing programs as well to encourage alignment with that wasted food hierarchy or avoiding the wasted food hierarchy?

Brenda Platt:
Yeah, I mean, sadly, I have more examples of bad policies. So if anybody listening to this has good policies, we want to know about them, so please send them our way. I mean, in New York City where they’ve cut community composting and they’re collecting it, all the bins in New York say compost, compost for collection, but it’s going to anaerobic digestion. So I mean, it just boggles the mind that even what local governments are doing is creating more confusion about what’s going on. And as a city like New York, which was such a leader in the space, is kind of taken two steps backward, but we appreciate the city for reinstating a lot of the funding for the community composters that it was able to do, but the fact that wasted food in New York that’s collected by the city is largely going to anaerobic digestion, which is being flared off is not a good policy. There’s so much work to be done here.

John Farrell:
Yeah, I think it would be arguable about whether or not it’s, you’re better off with wasted food in New York just feeding the rats rather than producing and flaring methane.

Brenda Platt:
Oh, you had to go there, John, rats. Well, now I have to address rats because most of our cities have 24-7 buffets for rats, open dumpsters and open containers. And when people talk to me about organic material for recycling, whether it’s composting or AD, they’re like, oh, rats and odors. And I’m like, no, we have rats feeding them 24-7. Once you begin to separate your food waste and take it out of open dumpsters and open trash cans and enclosed systems, we can begin to deal with our rat problems. So the wasted food is there, the rats are there. We just have to better manage them.

John Farrell:
Brenda, where can folks learn more about ILSR’s work on composting or anaerobic digestion, find that food waste hierarchy?

Brenda Platt:
Yeah, so if you go to ilsr.org/composting, you’ll get to our initiative website. And under there we have policies and graphics for the hierarchy. There’s other graphics, and we will also link pretty shortly to the US Composting Council’s brief that I mentioned on compost and digestate, dispelling the confusion.

John Farrell:
You also have a pretty cool map on your website, if I’m not mistaken. Can you just share what is on your map?

Brenda Platt:
So our map is called Composting for Community. You’ll find that too on our website. And there we track not only enterprises and entities that are collecting wasted food and composting them in their communities, but we also track policies and we have state policies and we have local policies. We have example zoning policies. So some of the good policies I’ll just mention, we do track states that have permit exemptions for farmers to be able to compost organic materials, wasted food on their farms, and be exempt from all the regulatory hoops that you have to normally jump through. So check out those policies.

John Farrell:
Well, Brenda, thanks so much for joining me to talk about anaerobic digestion. It’s such an interesting intersection of our work on energy and on food, and I think for me, it was really interesting to revisit it as having looked at it primarily as just an electricity generating tool previously, and to understand that there is so much more to think about in terms of what comes out. So I’ll be remembering your phrase, garbage in, garbage out when I think of digestion in the future. Thanks so much.

Brenda Platt:
Pleasure to be here with you. John.

***

John Farrell:
Thank you so much for listening to this episode of Local Energy Rules about anaerobic digestion with Brenda Platt, director of the Composting for Community Initiative at the Institute for Local Self-Reliance. On the show page, look for links to several resources we discussed, including ILSR’s Hierarchy to Reduce Food Waste and Grow Community, the US Composting Council’s Comparison of Compost and Digestate, a link to the Minnesota Environmental Justice Table’s work on closing the incinerator in Minneapolis, several positive policies to support composting and anaerobic digestion in responsible ways and a photo of a compost sock. Local Energy Rules is produced by myself and Ingrid Behrsin with editing provided by audio engineer Drew Birschbach.
I want to take a brief moment to thank Maria McCoy. Our Intrepid senior researcher, who you may have noticed is no longer listed at the end of the Local Energy Rules podcast credits. Maria recently left the Institute for Local Self-Reliance for graduate school after five terrific years, and I can’t thank her enough for all she did while working here. She produced 150 Local Energy Rules episodes, got them published, wrote summaries for the website, and on occasion had to do some gnarly troubleshooting. She hand drew the podcast logo that now shows up in your feeds, which previously looked like the bad marriage of some terrible clip art and a 1995 computer geometry program. And Maria was the person responsible for most of what you see in the energy section of ILSR’s website, including our national Community Solar Tracker, the Community Power Scorecard of State Energy Democracy policies, and much, much more. Maria, we wish you the very best. We hope to keep this podcast and our work up to your standards and we expect great things from you in the years to come. Thank you again. Tune back into Local Energy Rules every two weeks to hear how we can take on concentrated power to transform the energy system. Until next time, keep your energy local and thanks for listening.