Lorenzo Rosa | Fueling the path to net zero agriculture with hydrogen and ammonia
Agriculture-related emissions account for 12% of global greenhouse gas emissions. How will hydrogen fuel our path to net-zero agriculture?
In our 9th episode, Lorenzo Rosa, Principal Investigator at Carnegie Institution for Science and Assistant Professor (by courtesy) in the School of Sustainability at Stanford University, explains how hydrogen and ammonia will help us decarbonize the agriculture industry to feed the world sustainably.
Transcript
[00:00:00.00] [Music Playing]
[00:00:04.82] Karen Baert: Dear listeners, welcome to this week's episode of The Hydrogen Innovators, a podcast series is produced by the Stanford Hydrogen Initiative spotlighting bold innovators in hydrogen all the way from academia to industry. You can find our podcast series Hydrogen Innovators on Spotify or Apple Podcasts. I'm Karen Baert, a recent Stanford MBA graduate, entrepreneur, and innovation strategist at the Initiative.
[00:00:28.70] And I'm thrilled to be your host for this week's podcast. Today, we have the privilege to welcome Lorenzo Rosa. Lorenzo, welcome to The Hydrogen Initiative podcast. We are thrilled to learn from you today.
[00:00:40.55] Lorenzo Rosa: Thank you, Karen.
[00:00:41.66] Karen Baert: So a bit of background about Lorenzo. Lorenzo [? was ?] the principal investigator at the Carnegie Institution for Science at Stanford. And this is where we are today. He's also an assistant professor by courtesy in the Doerr School of Sustainability at Stanford.
[00:00:57.32] Prior to joining Carnegie, he was a postdoc fellow in the Institute of Energy and Process Engineering at ETH in Zurich. He holds a PhD in environmental science from the University of California, Berkeley, and a bachelor's and master's in environmental engineering from the Polytechnic University in Italy. Dr. Rosa has already published 30 peer-reviewed articles in highly respected journals, which is pretty impressive, knowing that he finished his PhD just two years ago.
[00:01:28.65] Lorenzo grew up in the beautiful pre-alpine region around Lake Como in Italy. And his childhood pastime was exploring the landscape with his younger brother, discovering new paths to reach the top. As the first in his family to pursue a college education, he paved the way for his brother, and later even his mother followed suit.
[00:01:49.38] Just as he led his family to higher education through discipline and determination, he's often one of the first, if not the first, runner to finish a mountain running competition. And in that same spirit, he leads his academic career.
[00:02:03.48] Lorenzo, over the last few years in the scientific community, you've made a large impact already. We talked about 30 articles so far, and they range across a wide range of topics in climate tech. But one very common theme is agriculture.
[00:02:18.66] You lead even a team of scientists and engineers to study climate adaptation and mitigation solutions with the goal of improving agricultural sustainability here at Carnegie. And so this is exactly the topic we would love to discuss today, agriculture and, more specifically, the role of hydrogen in reaching net zero emissions agriculture. Could you give us a high-level overview of your work and your research on that topic?
[00:02:43.44] Lorenzo Rosa: Yes, Karen. So agriculture contributes significantly to climate change. In fact, about 30% of global greenhouse gas emissions are from the agrifood sector. And at the same time, agriculture is significantly impacted by climate change.
[00:03:02.48] And in this role, agriculture can reach net zero greenhouse gas emissions by using hydrogen. And in fact, hydrogen can use in two main ways to reduce emissions in agriculture. One is with the production of fertilizers. In fact, fertilizers use a lot of hydrogen today. And if either version can be decarbonized using, for example, renewables from solar and wind or the so-called green hydrogen, we could decarbonize a great part of agriculture. About 15% of greenhouse gas emission from agriculture, or about one gigaton, is from fertilizers on a global scale.
[00:03:49.31] And secondly, hydrogen can also be used as a fuel to power agricultural machineries such as tractors and harvesters. And therefore, hydrogen can have an important role to reduce emissions from the energy-related emissions from agriculture.
[00:04:09.72] Karen Baert: Great. That's a super helpful overview. Now, you talked about fertilizers and hydrogen. My understanding is that ammonia is what is typically used as a fertilizer. Can you explain a bit the interplay between hydrogen and ammonia in the agriculture industry?
[00:04:27.18] Lorenzo Rosa: Yes. Ammonia is a key component in the production of synthetic nitrogen fertilizers. So here we are talking about nitrogen fertilizers, which are very important because they feed about half of the global population. So one over two people worldwide are alive thanks to ammonia that is synthetically produced through the Haber-Bosch process, which is a chemical process that was developed about 100 years ago.
[00:04:59.97] And this process combined a nitrogen that is present in the atmosphere with hydrogen. And to produce hydrogen, you need a lot of energy. And this energy today is mainly coming from natural gas and coal. So it has a huge carbon intensity.
[00:05:20.01] And just to give you some statistics, ammonia production with the Haber-Bosch process uses about 2% of global energy and emits 1% of global greenhouse gas emissions. So it's a very energy- and carbon-intensive process and is also very important, as I mentioned, to preserve global food security.
[00:05:40.24] And ammonia today is, indeed, produced with carbon-intensive processes. And there are three ways to decarbonize ammonia in the ammonia industry. One way is carbon capture and storage. so you have the current business-as-usual production methods, and you retrofit the facilities, the industrial facilities, with carbon capture and storage units.
[00:06:06.54] The second way is to decarbonize hydrogen. And one way to decarbonize hydrogen is, indeed, with the production of the so-called green hydrogen. So using renewables, such as solar and wind, to power water electrolysers and produce hydrogen. And the third way is to produce ammonia using biomass.
[00:06:30.88] And basically, when you use biomass, you can produce either hydrogen, in this case is biohydrogen, and then combine these hydrogen with nitrogen to have ammonia. Or the alternative way is to break down the molecules containing biomass and produce directly hydrogen from the biomass.
[00:06:53.28] In the industry, the ammonia industry is developing and is adapting to climate goals. And while today only 3% of global hydrogen is low carbon, so it's produced with water electrolysis, and ammonia production today that is low carbon is just 0.01%, or only 0.02 million tons per year are low carbon ammonia, in the future, projected demand-- projected production by 2030 is forecasted to be 50 million tons of low-carbon ammonia. So the ammonia industry is moving in the direction to decarbonize because it's very important to decarbonize hydrogen and ammonia to achieve, indeed, net zero emissions goals.
[00:07:44.67] Karen Baert: So great overview. So if we want to decarbonize ammonia, there's a couple of options. First, we can produce ammonia the way we produce it today but then add carbon capture. Other options are actually decarbonizing the hydrogen either through electrolyzers, so green, or biohydrogen. Can you give us a sense of this industry in 10, 30 years how will it look like and which of these decarbonization options will play the biggest role?
[00:08:12.26] Lorenzo Rosa: Yes. So as I mentioned, in 10 years, we will have about 50 million tons of low carbon ammonia compared to the current 0.02 million tons. So we are moving in that direction. We don't know how low-carbon ammonia will be produced. I guess the majority of low-carbon ammonia will come from solar and wind.
[00:08:35.51] So we will produce green hydrogen from solar and wind. So we'll be low-carbon hydrogen,. And then these hydrogen will be used to produce ammonia with the Haber-Bosch process. And I think this is going to be the majority of the production of ammonia, especially where you have cheap and flexible and persistent solar and wind resources, you can use them to produce low-carbon hydrogen.
[00:09:02.22] There is also this alternative way that is biomass and, in particular, biohydrogen. And these can be an option to produce low-carbon hydrogen. But it has several implications that are very important and need to be considered.
[00:09:19.89] Karen Baert: And I want to drill down a bit further on that biohydrogen because, obviously, at the Stanford Hydrogen Initiative, we focus on low-carbon hydrogen but acknowledge we need a wide range of solutions to decarbonize hydrogen. And so we've talked a lot about green, so hydrogen from electrolysis. We've talked a bit about [? blue, ?] so traditional hydrogen with carbon capture.
[00:09:41.65] We haven't talked much about bio-based hydrogen. Can you explain what that is exactly and how that fits in the broader green hydrogen landscape?
[00:09:52.92] Lorenzo Rosa: Yes. So biohydrogen is basically hydrogen that is produced from biomass. And there are different technologies to produce hydrogen from biomass. For me, the main two are gasification, biomass gasification, or steam [? methane ?] reforming from biomethane. And I want to focus on this second technology, which is the main one we are studying here in my lab.
[00:10:23.48] And basically, this route to produce biohydrogen with steam [? methane ?] reforming from biomethane consists in growing biomass. And very importantly, biomass has to be grown in a sustainable way that does not impact land, water, and biomass because we have to be very careful when we talk about biomass for bioenergy.
[00:10:45.60] So we have these sustainable biomass. We transport it to a bioenergy facility, in this case is an anaerobic digestion facility. And during anaerobic digestion, we produce the so-called biogas.
[00:11:01.23] And biogas is a mixture of CO2, about alpha CO2, and the other alpha is biomethane or renewable natural gas. Renewable natural gas can be separated through an upgrading process from CO2. And these renewable natural gas today is widely used, especially in Europe, in China, and but also in the United States as a fuel for our energy systems.
[00:11:28.89] An alternative way when you have abundant renewable natural gas, the consider also the fact that we will need hydrogen to achieve net zero emissions because hydrogen is a very important fuel in some [? hard-to-abate ?] sectors is to convert these biomethane into hydrogen. And this is through steam [? methane ?] reforming.
[00:11:49.63] So steam [? methane ?] reforming is a technology that is used today to produce 98% of hydrogen. And today, we use fossil natural gas as a feedstock to the [? steam methane ?] reformer, and we produce hydrogen. What I mean with biomass and biomethane is that instead we shift fuel. We go from fossil natural gas to renewable natural gas or biomethane.
[00:12:15.06] So we have this new feedstock. We produce hydrogen with steam [? methane ?] reforming. And we get low-carbon hydrogen.
[00:12:23.54] Importantly, biohydrogen is the only hydrogen route that can generate negative carbon hydrogen. And this can happen if you retrofit the steam [? methane ?] reforming process with carbon capture and storage. So when we talk about [? blue ?] hydrogen, we have hydrogen produced from methane with steam [? methane ?] reforming and carbon capture and storage. But this process at most is net zero.
[00:12:52.16] When we adopt the carbon capture and storage to steam [? methane ?] reforming from biomethane, since the carbon in the methane, in the biomethane is biogenic, so is from a shorter time frame because it's from the photosynthesis of plants, If we capture this carbon and we perform carbon capture and storage, we can generate negative emissions. So we can generate carbon-negative hydrogen.
[00:13:17.87] Karen Baert: And that kind of not just neutral but negative aspect is really, really interesting. Now, when I think about bio-based solutions, I always ask myself two big questions-- I would love to get your thoughts on that. One is like, would this impact food security? And secondly, how scalable is this really? Thinking about hydrogen demand is estimated to be around 600 million tons a year in 2050, How. Much of that could realistically be covered by bio-based hydrogen?
[00:13:48.98] Lorenzo Rosa: Yes. When we talk about biomass, we have to be very careful. So biomass growth requires a lot of land and water. And this land and water is also needed to grow food in the agrifood sector to preserve food security and also preserve biodiversity.
[00:14:08.72] And if we use biomass, we need to be very careful because, according to projection from a sample from the IPCC, to meet net zero goals, we will need a lot of biomass in different sectors. Biomass can be used in the power sector, can also be used to decarbonize [? hard-to-abate ?] sectors, can be used to produce fuels such as aviation fuels. So we will need biomass in a lot of sectors.
[00:14:38.12] And just to give you an idea, projections forecast that we will need an equivalent of area covered with trees to produce the amount of biomass that we need to keep global warming before 1.5 degrees. So we will need a lot of land and, therefore, also a lot of other resources such as water. And on this planet, we don't have this amount of land available because we are already using a lot of land and natural Resources to keep the demand that we have for food, fiber, and energy.
[00:15:13.59] So when we talk about biomass in particular here in my lab, we are studying the potential to produce bioenergy, in this case biohydrogen, from agricultural waste and residues. So these are, for example, crop residues, livestock manure, organic municipal solid waste, and also wastewater. So this is organic biomass that is a waste and residues of our human activities that we already produce in our daily activities.
[00:15:47.35] And instead of not using it, we would like to implement a circular economy model, where we use this biomass and we give a value to these biomass producing bioenergy. And if we want, we can even do carbon capture and storage and so generate negative emissions from these biomass.
[00:16:07.35] And these more sustainable biomass that use agricultural and waste residues is less impactful on land, water, and even food security compared to the so-called purpose-grown biomass plantations, so dedicated plantations that are going to use land, in most cases fertile land. And so they are going to create impacts on global food security.
[00:16:34.40] And just to give you some statistics, so in the lab, we are quantifying the potential for biohydrogen production from agricultural waste and residues. And we find that about 140 million tons of biohydrogen per year can be produced from agricultural waste and residues on a global scale. And this is about 7% of global final energy consumption, or about 2.5 times the current demand of hydrogen worldwide.
[00:17:09.27] So biohydrogen is a very huge potential, is about a 2.5 times the current hydrogen production. But we have to be very careful. And this is the technical potential. And then we will have, obviously, economic, social, and political constraints that will reduce this technical potential to the actual current potential.
[00:17:32.70] Karen Baert: On that note, we'd love to hear your thoughts on how the economics look like for bio-based hydrogen. Obviously, low-carbon hydrogen is still very expensive today. Green hydrogen, I think we're still at $8 a kilogram. We're hoping to get down to $2 or even $1. How does that compare to bio-based hydrogen today and in the future?
[00:17:52.09] Lorenzo Rosa: Yes. So I cannot give you an estimate of the cost per kilo, but I can say that the biohydrogen production is a promising pathway to produce low-carbon hydrogen, and even carbon-negative hydrogen. But it has several economic challenges compared, for example, to green hydrogen. And one key challenge is the cost of biomass.
[00:18:17.66] So you need to grow this biomass. In this case, it's a waste biomass. And you need to transport this-- collect and transport this biomass to a bioenergy facility. So transport is key here and is, let's say, the bottleneck when you talk about biomass.
[00:18:33.58] And additional also these conversion processes of biomass to hydrogen, they require specialized equipment, which also can add cost. And another challenge, again, is the limited availability of biomass. So maybe you have a demand for hydrogen in a certain region, but you don't have enough biomass. So there are a lot of factors that need to be considered to produce biohydrogen. And I don't have an estimate of the economic cost, again. But I think it's not close to the $1 per kilo of the current hydrogen production from steam [? methane ?] reforming.
[00:19:17.92] Karen Baert: That's helpful. And I think, in general, that kind of model of waste to energy or waste to value is really attractive. So looking forward to progress there and seeing what estimates play out in the next years.
[00:19:30.55] I'd love to talk a bit more about water. You've published a lot of work on water availability and scarcity. One of the topics you talk a lot about when we think about green hydrogen, so hydrogen from electrolysis, is the fact that we need a lot of renewable electricity but also water. Curious to hear your thoughts on whether this will intensify the challenge of water scarcity in certain regions in the world.
[00:19:54.57] Lorenzo Rosa: Yes. So water is a very important aspect that should be considered when we deploy these new technologies. And every human activity needs water. And even hydrogen production requires water.
[00:20:08.53] And when you produce hydrogen, in this case green hydrogen, from water electrolysis, you need some water to break down the water molecules to hydrogen and, indeed, produce hydrogen. And the stoichiometric water demand to produce hydrogen from water electrolysis is 9 liters of water per kilo of hydrogen. And then we need about 15 additional liters of water per kilo of hydrogen in water treatment. So you need a pure water when you feed it into the electrolysers.
[00:20:42.88] So about 24 liters of water per kilo of hydrogen are needed to produce hydrogen with water electrolysis. And when you produce large amounts of hydrogen, obviously, we need also large amounts of water. And on a global scale, water demand for hydrogen, for example, in the future scenarios, where we will need 600 million tons of hydrogen per year on a global scale, water demand for hydrogen is negligible compared to the water that we have locally available. We did a rough estimate and is about 0.5% of the global water available, so it's very negligible.
[00:21:24.71] But on a local scale, these projects, they can have water scarcity impacts, especially considering that solar is present in-- solar energy and-- abundant in solar energy is present, especially in semi-arid and desert regions, which already face water scarcity. The additions of these projects to produce hydrogen is going to exacerbate water scarcity.
[00:21:52.28] So these are very important concerns that should be accounted when these projects are developed. And therefore, local assessment are needed to determine the feasibility of each project. And some regions are going to be suitable to produce hydrogen without creating water scarcity. Other regions will create water scarcity.
[00:22:16.70] And there are solutions to water scarcity. One, for example, is desalination or the use of nonconventional water resources. But obviously, these will add additional costs in term of energy use and other environmental impacts. For example, desalination is energy intensive and also generates brines, which have environmental impacts on ecosystems.
[00:22:44.09] Karen Baert: That's very clarifying, also, of how you distinguish the kind of global versus local implications there. But I also want to take a step back. One of the things I really like about the work of your group is that you go really deep, but you also have a good macroperspective on the different challenges that our Earth is facing right now, including carbon, so climate change, water scarcity, food challenges. If you had a magic wand to solve one of these challenges or change one of these things, what would it be and why?
[00:23:15.85] Lorenzo Rosa: I would choose to phase out all fossil fuels and replace them with affordable, accessible, and widespread renewable energy. And by having affordable, cheap, and widespread renewable energy, we are going to be able to solve a lot of challenges in agriculture and food security, water security, and even climate change. For example, with cheap, affordable energy, we could produce fertilizers, so we could produce low-carbon hydrogen, produce fertilizers.
[00:23:56.00] And we could produce fertilizers locally. So we could have distributed fertilizer production. And these, indeed, can be used to improve agricultural productivity in regions where fertilizer don't reach the field because of economic reasons or because transport is a bottleneck, to transport the-- to get the fertilizers in that location.
[00:24:20.36] If you have affordable, cheap, and widespread energy, you can even get additional water. For example, you can produce fresh water from nonconventional water resources, such as saltwater or brackish water. And with unlimited energy, you can also stabilize the climate. So you can do some carbon dioxide removal. For example, you can run direct air capture facilities to capture CO2 and store it underground.
[00:24:53.42] Karen Baert: That sounds like a great world. I'd sign up for it. [LAUGHS] And Lorenzo, I want to talk a little bit more about your personal journey. And your academic career has guided you all the way from Italy to, I think, Sweden, University of Virginia, Berkeley, then back to Europe, to Zurich, and then finally Carnegie or Stanford. What's home for you professionally and personally? And what has been guiding or driving you through this journey so far?
[00:25:22.82] Lorenzo Rosa: Yes, these are great questions. So my home professionally is the Bay Area and in particular now is a current institution for science, is a great place for me to be here. And I'm very honored to be part of Carnegie Institution and the team of Carnegie Institution for Science. And my home personally is Italy. I'm Italian, so I'm very attached to my origins.
[00:25:49.50] I'm from a very small town in the Lake of Como area in North of Italy with just 1,000 people. And we-- I grew up in this magic place in the mountains close to the lake. So that is a very great way to grow up, I think. But professionally, I'm very attached to the Bay Area and the Carnegie.
[00:26:13.97] And what drove my journey so far, so as I mentioned, I'm from this small town, which historically relied on agriculture. And in recent years, in recent years with global warming, we see more often problems of droughts, which are affecting not only Italy but even California as we are seeing. And this has motivated me to perform research that aims to bring a solutions directly to solve our day-to-day life and bring mitigation to these challenges that we are facing.
[00:26:58.46] Karen Baert: That's such a beautiful story, and your community and family back home must be so proud of all the ways in which you've been creating change already in your career. I also want to end with a question that, as you know, we ask every guest on the podcast and the strong belief that we all stand on the shoulders of the giants who came before us. To use Isaac Newton's words, it's standing on their shoulders is what makes us see further. In that context, who inspires you and why?
[00:27:27.17] Lorenzo Rosa: Yes, I have to acknowledge that I stand on the shoulders of giants. And in this case, I would like to acknowledge my mentors and colleagues, which have been instrumental in shaping my academic career and my professional journey. And I would like to mention my academic father, Paolo D'Odorico, at University of California, Berkeley, and my mentors during my PhD in Berkeley, such as Inez Fung, Dennis Baldocchi, and Jeff Reimer.
[00:28:04.19] I would like also to acknowledge Prof Marco Mazzotti at ETH Zurich. He was my postdoc mentor during my postdoc. And also I'm a fortunate enough to be at the Carnegie Institution for Science. And I have amazing colleagues and mentors upon whom I can learn and grow as a scientist.
[00:28:27.47] Karen Baert: Well, Lorenzo, Dr. Rosa has been a privilege to learn from you. I feel like we'll need a new episode every year because there's so much happening in this space and so much amazing work you're doing together with your group. For our listeners, Lorenzo just published a new article, so definitely go check it out. Thank you so much for your time today, and we look forward to continuing to follow all the amazing work you're doing.
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[00:36:09.12] Karen Baert: That's beautiful. And you're definitely an inspiration to me and many, many others on this campus and far beyond that. So, Professor Majumdar, thank you so much for your time today, and thank you for sharing your knowledge and vision with us.
[00:36:22.41] Arun Majumdar: Thank you.
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