 Hi everybody! Hi! My name is Jennifer Milne and I'm an assessment analyst here with the Global Climate and Energy Project and over the years what we've done is developed a portfolio of research that's aimed at energy technologies that reduce greenhouse gas emissions and along that way we delved into an area called BEX which is bioenergy with carbon capture and storage and negative emissions. Now I think from this morning you've probably all heard about BEX to some degree right? From Catherine's talk. So what we're going to do with this panel is delve a bit more into that topic and talk about some concerns, some feasibility, the scale and what kind of future needs there are. So what brings us to this initially is that you've heard of the Paris Climate Agreement of course which was a landmark agreement that pledged to keep emissions at CO2 levels to a degree where temperature would not go above two degrees above pre-industrial levels. Now the issue with this is that that that estimate that says that we can do that, a lot of those estimates include a technology called BEX and negative emissions technologies but as yet that's an unproven technology. Is anyone surprised by that or do you all know that? So that's maybe a little bit of a concern right? So all the pieces of that technology exist but it hasn't actually been demonstrated at scale yet. Portions of it have been at some scale and we're going to talk about that. So we actually have key experts in the area here on our panel like to introduce you to Chris Fields. He's the Director of the Woods Institute here, Woods Institute for the Environment here. He's an ecophysiologist and he has a long history and biomass research topics as well as he was the co-chair of the IPCC. Which one was it? Working Group 3? Yeah, Group 2, sorry. So he has a lot of thoughtful, thoughtful things to say about this topic and many others. And Catherine Mack who you met this morning, she was also a student here at Stanford in ecology and engineering and she co-director science for the IPCC working group too, right? And she's now a senior researcher here. Sally Benson, last but not least, she's essentially my boss here. She's the Director of GESAP which is the Global Climate Energy Project. Also co-director of Precourt Institute for Energy which is partly why you're all here. But she's also a renowned scientist and researcher in CCS, so carbon capture and sequestration. So recently, thankfully, they've collaborated on a number of papers that have tried to delve further into the area of facts and look at just what the potential is, thinking about land use and consequences of CCS and scalability and everything. So I want to go first to Chris. And can you just set the stage for, you know, the need for negative emissions and the reality of facts and how you came to be interested in this area? Sure. I think you already know from your background or from material heard this morning that we're getting pretty close to the total cumulative emissions that are consistent with a limiting warming to 2C or less and we're very, very close to the cumulative emissions that are consistent with limiting warming to 1.5C or less. And puts an increasing urgency on figuring out how to bring carbon emissions quickly down to zero. And if you just think about the arithmetic options for doing emissions reductions, and we have a certain budget that we can emit forever, one option is to aggressively decrease emissions now so that we can slide down a slope and the cumulative total comes up to no more than the allowed budget. For another option, if the were feasible, is to emit a bunch now and not worry too much about the pace of emissions reduction but activate later in the century a whole series of technologies that produce negative emissions that remove CO2 from the atmosphere potentially at the same time may provide energy. If you could do that it would be helpful for two important reasons. One, obviously it would let you deploy current strategies at a pace that made sense. Also it allows you to take advantage of the fact that at least in the economic models people want to discount the future. And even though we're not 100% sure how we would do these negative emissions, if we have some kind of a feel for what the cost might be. And if discounting means, wow, we really don't care that much about what the costs are in the future. You wonder whether compelling motivation to continue emissions now with the idea that we'd activate large amounts of negative emissions in the future. Most rational people would say there's some problems with this approach. Most economists wouldn't and so that's the thing that motivated us to take the approach that we took to try and figure out what's really likely to be possible with negative emissions. If we want large amounts of negative emissions in the future what do we need to start doing now and what are the kinds of constraints we might run into given what we know then. Thank you Chris. So with that I want to go to Catherine now and you did this paper on right sizing and tell me what that means because this is getting a bit more into the granularity of it and Bex is not the only negative emissions technology. And in that paper you describe some of the others and the differences between them. So can you say a little bit about what right sizing means and what you discussed? Great. So as Chris described in these trajectories of thinking about how we might get to two degrees Celsius and rain in some of the worst damages from climate change, there's clear understanding that not just traditional emissions reductions but also approaches for pulling CO2 out of the atmosphere might be very helpful. I think a key distinction also is are we thinking about them at any one moment in time or is this flexibility really about the long-term trajectory? So I guess what I'll pivot towards in terms of describing right sizing and the different buckets of approaches that are relevant is really to emphasize that when we imagine the end game energy system where we are no longer putting CO2 into the atmosphere, a 100% reduction that Sally had as answer D there this morning, there may really be a role for removing CO2 from the atmosphere. And if we're going to be deploying it in the end game we do need to be building the experiences now. I think what we want to avoid when we think about these buckets is that it's going to be a miracle that emerges in 2080 and saves us even though we haven't been doing anything before that. So the three buckets that I introduced this morning just as I was realizing that I was totally running out of time span on a spectrum that runs from biology to engineering. So first question is how do you get CO2 out of the atmosphere? The most tried and true way to get CO2 out of the atmosphere is to rely on photosynthesis which I guess has been on planet earth for what will point two billion years. And essentially that's the idea when plants grow they take CO2 out of the atmosphere and they turn it into the stuff of life biomass plant matter. So strategy number one for removing CO2 from the atmosphere is to plant a tree or to change the land management practices that we apply such that there is more carbon stored in the trees and the plants are in the soils. Category number two running on the spectrum from biology to engineering still relies on photosynthesis to get CO2 out of the atmosphere but it's a little bit different in this circumstance in that you're using that biomass to generate electricity or fuels and then you're capturing the CO2 out of that energy conversion process and sending it underground through carbon capture and storage which Sally will be describing a great length. And the third bucket is fully engineered the kind of prototype there is called direct air capture where you're using engineering, sorbent solvents membranes to get CO2 out of the atmosphere and again injecting it underground. There are lots of other options that fall on this spectrum whether it's enhanced weathering or biochar but pulling them on that spectrum of total biology to total engineering can be a helpful way to parse the landscape. Great so before we go to Sally just have questions ready everybody so probably halfway through we might go to you so if anything occurs to you in the meantime feel free to raise your hand as well I mean there will be a time for questions later but if there's anything that's so pressing that you can't wait until the end just raise your hand and we'll invite you to ask that. Sally so tell us about CCS and about I guess the feasibility CCS and doing it at scale and then we'll come and discuss one of your recent papers that was on the co-location and I'll bring the others in to discuss that too but tell us about CCS and some of the I guess the barriers to deployment right now. Okay so you've heard about CCS probably a lot of times but no one's ever described that so CCS stands for carbon capture and sequestration sometimes it's also called carbon capture and storage they're the exact same thing and the idea as it was initially conceived is if for example you had a coal plant and instead of allowing the carbon dioxide just to go into the atmosphere after you burn the coal that you would put in a chemical scrubbing unit much like we have scrubbers for other things from coal plants but this time it would be for carbon dioxide and that you would take that carbon dioxide and then separate it from the sorbent that you use to capture it and you end up with a nearly pure stream of liquid carbon dioxide once you compress it so then the idea is that you take that and you can put it in a pipeline and you pump it deep underground and when we say deep that it's at least one kilometer but it could be two or three kilometers it's really as deep as we sort of know how to drill and that if you pick the right location that the carbon dioxide that you pump underground will stay there essentially forever so then you can think about well where could you pump it underground so the most obvious place would be an oil reservoir or a gas reservoir because we know where those are today and besides we've spent you know the last 50 you know or 100 or 75 or how it depending upon how old the oil field is we've been spending all that time taking fluids out of the ground so presumably if you try to put something back in the ground there would be room to accommodate it so that's pretty obvious for oil and gas reservoirs and what's also good about those is that we know that the oil and gas wouldn't be there unless there was a rock on top of that reservoir that was sealing the carbon dioxide in okay so so you know that it sort of got the perfect conditions for storing carbon dioxide so so that's one obvious place but it turns out that if you look at the global deployment of carbon capture and storage there are a couple of things one oil and gas reservoirs don't exist everywhere right so so say you're you know in someplace in china and you want to sequester the co2 if there's no oil reservoir there you're kind of stuck so that um got people interested in well are there other options and the major other option is to put the carbon dioxide into what's called the saline formation which is basically a sandstone formation just like a typical oil reservoir but instead of being filled with oil or gas it's filled with very salty water and the water is so salty that you don't necessarily want to use it for anything else it's not really very valuable and so that if you could find the saline aquifers which had a good sealing layer over it that maybe that could work too so that was the the idea there so the the norwegians then very interestingly back in the early 1990s norway passed a tax that said for every ton of carbon dioxide you emit from an offshore oil and gas activity you have to pay $50 a ton so that was a really big tax so so they had some gas fields natural gas fields that had a high concentration of carbon dioxide in them that they had to separate the carbon dioxide before they can sell the gas so so here they were with their offshore facility to separate natural gas from carbon dioxide and they had a choice they could emit it into the atmosphere and pay $50 a ton or they could try to do something else so they said well we're going to try to sequester it in the saline aquifer so they were the first test case of of this so so so that too has been proven to be possible so I'm going to wrap up now just but I say one more thing so when I first started working on this I I was given a PowerPoint presentation from somebody from Princeton University that talked about this idea of saline aquifer sequestration and I and I thought oh this is the most ridiculous thing because I'm actually a hydrologist that's my discipline and I thought oh this was so silly and so I kind of set out to prove it too so I I looked at California and I said well these are all the emissions from California I forget what it was at the time I don't know 50 million tons a year something like that and I said let's imagine we want to sequester all the co2 emitted in California in saline aquifers or oil reservoirs in California and could you do it and I came up with the idea you can do this for 300 years so it's like oh well maybe this isn't such a silly idea after all so so that really opened my eyes to the to the potential of this so uh anyway is that is that okay yeah that's great thank you yeah so so with that um so thinking about biomass so this is a in some ways it's a nice system because it has the potential to supply energy as well as sequestering carbon so that's the ideal but but there's lots of there's lots of issues right that it's not so straightforward so can can we talk about just about the potential of biomass and and we can localize in on the us and the study you did there in the co-localization of the ccs sequestration sites and the the biomass potential because that can be limiting as well so um uh maybe start with chris talking tell us a little bit about the limitations of growing as much biomass maybe i'll just say a couple things about the way to think about bringing plants into the energy system and then go to katharine about the co-location issues so um photosynthesis the way to capture radiant energy take sunlight energy and convert it into chemical energy in in the chemical bonds in plants and you can obviously get those back out as energy through combustion or through um pyrolysis making the turning the plants back into gas and then combusting the gas the the challenge is that photosynthesis is not terribly efficient because biological processes go it's it's really efficient but a typical forest or a cropland doing really well if it converts half a percent or one percent of the energy content of the sunlight in the energy in the biomass and so whenever we talk about getting energy from biomass we're we're talking about a technology that doesn't compare very favorably in efficiency terms to what we can get out of photovoltaics on the other hand there aren't very many photovoltaics self-assemble from planting a seed and so when we're talking about low technology approaches that there's some wonderful features of having essentially your solar capture processing chemical assimilation plant self-assemble the challenge is that it takes a lot of land in order to capture a lot of sunlight energy and to grow a lot of plant matter it takes land that has good soil sufficient water and sufficient nutrients so when when we started looking at the ambition for negative emissions later in the century and said well how much land would be required in order to offset between 10 and 15 billion tons of CO2 per year with the standard productive potential of land it's really a lot it's on the order of as much land as we use for agriculture now it's around 10 percent of the total land area of the planet and when we think about deploying a new kind of cropping system at this kind of scale we have to ask bull is there enough land left over for food production is there enough land left over for nature is there enough land left over for sort of everything else and also could we conceivably think about deploying a new agriculture system that would go from nothing to the scale of as much agriculture as we've got over a few decades and so those were the kind of questions that led us into setting up the question of how much energy you could get from BEX without necessarily saying anything in detail about what the specific conversion technologies would be but using these big picture framings about how much plants can grow or where their storage capacity and what are the issues associated with getting from the plant into storage pass it over to Catherine and talk about what the answer is great so we actually did two of these co-location studies so maybe I'll introduce the first one and then I'll even punt down to Sally for the second so if you think about where is BEX happening in the world today does anyone know the answer to that question I mentioned this morning that is at present in terms of biogenic biomass drives CO2 that's heading underground we're only at 0.01 percent of the deployments in the two-degree Celsius scenarios from integrated assessment models and that 0.01 is happening in Decatur, Illinois at a bioethanol facility if we also think about well then where is at least bioenergy happening in many cases it is biofuels but there's also bioenergy in particular wood chips going from the US southeast over to Europe but as a first proxy unless you're putting biomass onto ships the transport part is hard a road transport of biomass is very bulky compared to coal for example or compared to oil building pipelines raises all sorts of complexities around nimbyism and permitting and even moving incredibly fast there are some number of years much like a decade or two built in there so the co-location philosophy was that near-term entry points for bioenergy with carbon capture and storage could be places where you've got biomass above ground and potential for injecting it directly below ground so without need for long distance transport of the biomass and without need for long distance transport of the CO2 in pipelines so we first started with a global analysis this one was led by Peter Turner a postdoc at global ecology and in terms of the geologic storage part it's coarser at the global scale we use a database that Sally recommended where you can look at highly perspective sedimentary basins where there's a good chance if you really were to do all the assessment needed that there could be storage potential there and in terms of the global availability of biomass we use the modus data set and we essentially said what is the amount of biomass produced by all ecosystems on planet earth in any one year and how much of that could you harvest sustainably recognizing about half of the biomass is underground and you wouldn't want to pull all of the stuff from the top as well so if you basically say there are 80 billion tons of co2 equivalent in all of the biomass globally produced each year that you could potentially harvest we next said how much of that over lies storage basins and that's about 8 billion tons of co2 equivalent so compared to 10 billion tons in models that's a pretty big number but we probably don't want to deforest the planet for becks and we probably don't even want to use our best agricultural land as chris was introducing so if you then drill down to marginal agricultural lands at the global scale overlying storage basins that's 1 billion tons of co2 equivalent next phase that i very briefly mentioned this morning and i'll pass over to sally for this one was to say well can we extend this at very high spatial resolution in the us where we've got much better assessment of the storage potential across different basins and we also have much more refined estimates of biomass potential in particular through the us do e billion tons study okay so as i'll talk about the us study so thinking back to what alisha was saying the idea of moving from global to local this was very much our motivation for the us-based study and it's really the only place on the planet today where there's high quality county level data available for biomass availability together with really county level information available on sequestration potential so that led us to do this and just to say a little bit more about the study so ej bike was the the lead on this study she's a student in energy resources engineering and kathryn and chris had been talking about doing a collaborative study where you know they would bring their expertise and and i would bring our expertise and i asked her i said well you know i know this is not what you're planning to do which she wasn't but this is such an amazing opportunity to work with this team i think you should go for it and she said yes and so so i just bring that up that if you find yourself in a situation where an opportunity comes up that may not have been exactly aligned with what you expected to do you know at least keep your mind open to it because i know for for ej it was really fantastic okay so now to get back to the study okay so we had county level data on biomass so so we relied on the billion ton study and that looked at ag residues it looked at dedicated bioenergy crops it looked at other waste it looked like at forest residues and so forth so it had quite granular data and we looked at what was available there it turns out across the united states it was about half a half a billion half a half a billion tons per year of co2 equivalent was actually point four and so so that was an interesting number but then we had to look at this issue of co-location so the first thing we said is is it co-located with the sequestration resource and and when you said that now only about a third of it was actually co-located with a sequestration resource so if we're taking transportation off the table that means it's limited there so then we asked two other questions we said well okay yes it's co-located but is there enough storage capacity there um and that was first part of it the second one is could we inject a co2 at high enough a rate which without it building up the pressure in that information and it turns out that the in all cases well except two out of thousands of counties we looked at that the there was plenty of capacity and plenty of injectivity so it really the co-location was the key there but just to say a little bit more about this so so the idea is bioenergy plus uh plus uh plus carbon capture and storage so then the question is is well how big are these power plants and it turns out they were all very small about 10 megawatts and to give you a little perspective on our campus when we had our own power plant it was 50 megawatts so you can see that for a whole county you know 10 megawatts so it's a small amount of power generation uh and it's also a very small amount of co2 so normally when we think about questions of scale we think oh gosh it's going to be so big can we accommodate all of this well here it was just the opposite it's like wow this is such a small project you know how would you do this if if you had a different paradigm of really a very small scale project which sort of opens up other questions about how we might think about doing this in different ways like dissolving the co2 instead of just injecting it as a separate phase so okay thank you so that actually brings me to the feasibility and kind of near-term opportunities and you touched on this before Catherine about talking about the plant in in Illinois it's a carbon fermentation facility so you you did this paper techno economic assessment looking at those near-term opportunities so can you say a little bit more about them but also I guess discuss around the the probability that those are not actually negative emissions technologies per se because of the the carbon life cycle but what would be the benefits of of kind of going down that pathway great so I'll give a background on this study that we did but then biofuels is a big rich area and I think chrystal have more nuance insights on that broader theme so we basically wanted to say as I briefly mentioned this morning if we take current infrastructure as a given current technologies as a given and even current policies and existing pricing a carbon that exists not supervisibly in some cases but implicitly in a number of them with those current sets of infrastructure technologies and policies how far can we go where could you inject biogenic co2 underground and so if you are looking for cheapest most commercially ready even profitable near-term opportunities the place you want to look is biorefineries and essentially what is happening is that in the fermentation process that generates biofuels you get a near pure co2 stream that comes out of that process so what that means is that you can capture that co2 compress it and ready it for pipeline transport in most cases under $25 a ton in the space of carbon capture and storage and Sally can give you all the details on the pricing elsewhere that is very very cheap so what we essentially did was an analysis of the 216 bio ethanol refineries that exist in the US they are mostly in the corn belt and if we had a map of the sedimentary basins in the US up right now what you would notice is that except for the Illinois basin there aren't basins under the corn belts so you've got a ton of biomass a ton of biofuels a ton of biorefineries but nowhere to inject it so what we did in combining the process engineering of what's happening at any one facility with lifecycle assessment of what happens to the carbon we then did a spatial optimization of at a given price for co2 what type of pipeline network might be profitable under that type of policy environment and as we were doing this the 45 q tax credit was coming under revision and in the budget act past in this past February pricing now is going to increase up to $50 a ton so we did a scenario of $60 a ton if we adjusted all the scalars it's actually quite close to what would be coming online for 45 q and actually at that price you could capture most of the co2 being released through ethanol fermentation in the US right now that's around 40 million tons per year then if you look at the more implicit pricing around low carbon fuel standards for example california is now developing a ccs protocol where this could apply the price actually is usually implicitly or on the traded markets they're much higher and sufficient to essentially make it profitable to generate ccs or to attach ccs to most bioethanol refineries in the US except that demand on the california market is nowhere near the magnitude of what could potentially be provided so i think jenny to your point bio biofuels made essentially as corn ethanol with ccs are less carbon intensive but they are not net negative in their entirety so really i think this is a way of thinking about going from 0.01 percent of biogenic co2 going underground as compared to the deployments in the iam scenarios all the way up to 0.1 percent that would be a huge learning experience in the ccs space because you've got 200 of these facilities potentially even though it certainly isn't the end game it's more kind of a potential connector to other biomass feedstocks moving forward great yeah so at this point are there any questions from the audience i have a question that said to sally on ccs said like how now it's more into reserve originary movement how do you monitor the process especially that you mentioned that it has to do with the pressure regime down there and where you are actually trying to inject co2 here and there on a specific area right so there you do a number of things one is you measure the pressure in the formation directly there are gauges you can put in the reservoirs and are very accurate and so you always do that the second thing that you do is you use seismic imaging so seismic imaging is like a you pass seismic waves through the earth you know so you basically have a machine on the ground surface that vibrates the earth's surface it sends sound waves through the earth when it interacts with the rocks it makes a reflection which you can then detect that and you can so it's like a sonogram for your body but it's for the earth in essence and that's very good at figuring out where the carbon dioxide is there are also other methods for if you have multiple pressure sensors you can actually invert that data using you know complicated algorithms to figure out where the co2 is moving there are electrical resistance tomography so instead of using seismic energy you use electrical energy or electromagnetic energy energy for imaging so there are a whole variety of approaches and there's a ton of research on on that kind of thing including research here on those topics in space yeah i think the volumes just will never ever ever work out yeah i mean just to sort of to first order picture taking all of the fossil fuels that we produce every year and just trying to ship all those to space that that would be pretty hard in and of itself and carbon dioxide would be be even harder because it's less dense and yeah so it would be really hard though it's a wonderful idea so like oily vascular parts are effective often because you have like the epistome so but there are also places where with a small perturbation you know you can extract those kind of things right so i'm wondering about size of the city in the local area can you because it's so cool so how about right yeah that's a great question so um so i think you heard earlier from steve graham about the potential for induced seismicity associated with injecting fluids underground and over the past five years or so uh the amount of water that's been injected underground in certain locations you know oklahoma being the main one um has accelerated rapidly and they started having all of these earthquakes there and and it uh led to real concerns that's like oh my goodness if we did carbon capture and storage would we start having lots of earthquakes so that was number one so the experience to date with all of the existing projects there have been no felt earthquakes with any of the existing co2 storage projects and there are 18 different projects so so that in and of itself doesn't appear to have been a risk at least for the scale that this has been implemented on in the past now that's not to say in the future if you injected at much higher rates or in different locations you might have to be concerned about that um but so that's number one is do you have seismicity the second question is is if you do have seismicity does that mean that you're creating leakage pathways um the seismicity that's associated with ease it's not like breaking fresh rock uh the the places where you have seismic events or there are pre-existing faults and you're basically getting slip along those pre-existing faults most of those faults when you take a look at them in detail they have actually a big zone it's called the gouge zone which is actually a very low permeability zone that's been created by you know geologic time period you know friction between either sides of the fault so the faults tend not to be particularly permeable in those places so so the risk of leakage from induced seismic events appears to be quite low um and uh and again the risks of the events themselves are very very highly site-specific uh Mark Zobak is one of the world leaders and anticipating um induced seismicity and he was actually the one who sort of diagnosed what was happening in Oklahoma and helped make the case that they needed to cut back on water injection there um yeah so the other part of leakage people talk about a lot is leakage from all of the other penetrations from existing historical wells and what's the state of thinking about that right yeah so so the biggest vulnerability uh for an oil or gas field is that you have all these old wells that were drilled there they might have been drilled you know 75 years ago when nobody documented how they were constructed very carefully or the construction practices may have not been up to the standards we have today so each of those creates a vulnerability so now if you want to go into any place where there is a well uh or do sequestration there you have to basically characterize that well you have to go in and get logs you have to get uh all the construction records and if there's any concern that it would leak the requirement would be that you would plug it up um you'd still need to monitor it because plugging it up is a non-trivial issue but as long as you know where the wells are you probably are in pretty good shape i think the bigger risks are when you don't know where the wells are and there are some fields particularly really old fields where the records are just so poor that um you know you always have to be vigilant about that okay well so so there's potential essentially for CCS that's not really a limiting factor but can we talk about um the potential to buy mass a little bit more and think about feedstock choices and also what policy things might need to be in place for some technology like this to take off in a in a sustainable way that wouldn't impact ecosystems as much you also um wrote a paper on um rates of land use transformation and that it would bring unprecedented rates uh about if we were to do this technology so can you talk a little bit more about the details of that and and what you see is as the potential that this could get to if that's what you want and what's needed and if we don't have that what else do we need to do with our energy system for example to to get to a reasonable amount of co2 emissions in the atmosphere well when we think about these negative emissions technologies each of them has a series of associated costs and benefits and for some of the biomass ones there's a compelling set of co-benefits that make them potentially worth more than just the negative emissions components so that if we take areas that previously had forest and reestablished forest or if we limit the rate at which forests especially in tropical areas are cleared there's the potential to improve habitat for animals and endangered plants the potential to improve water quality and the potential to lead to a wide range of habitat benefits currently the co2 emissions from cutting down forests it's not in the order of three or four billion tons of co2 per year and really simple way to decrease the current emissions or to even create sanks is to simply slow the rate of deforestation or to plant new forests and in many cases planting new forests provides negative emissions actually net removal of co2 from the atmosphere and storage and biomass at the scale potentially a billions of tons of co2 per year meaningful fraction of the total emissions in a way that that also improves the habitat for people around the world and so the those kinds of strategies are really rich with opportunities and most of the analyses indicate that you know at carbon prices of anywhere from 10 to maybe 100 a ton of co2 the amount of sequestration that could occur as a result of these natural climate solutions on the order of five billion tons per year about 10 percent of current total emissions and a meaningful amount that could be sustained over some decades that's a really big advantage and it's one that's that's worth thinking about in the context of all of the different technologies we look at then as we we shift more into the engineering heavy technologies that Catherine talked about had the possibility of generating meaningful jobs in rural areas of providing energy resources in places that are currently energy limited and so they're it's worth trying to figure out what are the possibilities with the with the co-benefits and one of the really interesting features of the US study that Sally talked about is that in that study most of the feedstock for the biomass energy production was residues from the parts of the crop so we don't eat or the parts of the of the wood production that aren't going into the boards that people use for construction and so if you just look at at residues either on the production side or on the after-use side you can end up with a with a meaningful amount of material and an interesting feature of that is that this is generally material that is is sort of clogging our cities now as a in landfills and so if we can be more thoughtful about how we how we process waste that could be another kind of a win-win and I think the the message from all of these negative emission studies we did that came through most clearly to me is that we should really be focused on opportunities where there are win-wins where we get to not only get a negative emission but we also get another benefit in waste management or habitat improvement or creation of jobs that really is likely to turn the balance in the absence of that you run very quickly until limits on how much resources are available for expanding our ability to survive this maybe i'll pick up the second part of your question so just so it doesn't come off as our presentation approach being very critical of the integrated assessment models i'm actually going to add in a little bit of nuance of how we think about applied policy analysis in the climate context i think this week you're going to hear from john wyant who is one of the stanford experts who really has coordinated communities globally in this space of modeling how our energy and land use systems might come together in transforming through time and i also just this afternoon spotted in the audience a student incoming student who's been working with leon clark over the last two years another one of the leading experts in this area so what are these models trying to do i think the absolutely essential thing to realize is that no one has any clue what technology prices will be in year 2100 no one has any clue what global gdp will be or how that will be distributed through regions and if you ask anyone who really evaluates how do you trigger change in our energy system they will say two of the most important lovers are technology prices and the policy backdrop yet those are the two biggest uncertainties moving forward so what integrated assessment models are doing is they are probing the space of extremely deep uncertainty and by deep i mean is the uncertainties where you can't put probabilities on what is going to happen these are unknowable features of the future and instead you're doing a scenario based analysis way far out many decades into the future so when john wyant for example talks about these integrated assessment model results is what he'll say is that they show you sensitivities in these systems they help you think about near-term priorities but what you don't want to do is take the numbers literally in year 2100 because they're completely dependent on technologies that don't yet exist i don't know if in arun's presentation this morning he had this slide of his that i really like that's something like uh before a technology breakthrough happens it seems like it's science fiction and then after the fact it's obvious right so if you told me when i was the little kid that i was going to walk around with what at that point was like this apple 2 e in my pocket i of course would have thought that that's fiction step forward to the modern world and we all have them so energy system involves longer time uh trajectories as compared to software but i think that's a really key feature so just to put a point of nuance there i think when we criticize integrated assessment models i think the key thing is that the criticism is we shouldn't take them literally we understand that we need to transform our energy and land use systems towards zero emissions of the long-lived forces constant emissions of the short-lived forces like methane we understand that that involves a whole bunch of pieces coming together i think the real nuance here is that we probably don't want to assume billion tons of removal through becks at the same time that carbon removal and much smaller scales can provide all of these co-benefits as well as being an important part of our emission reductions portfolio right exactly and so that brings us to thinking about what are the other changes that we can make to get to zero or negative emissions and our energy infrastructure is one of the biggest emitters the biggest emitter so what what can we do with our energy infrastructure and this is a this is a huge complex picture it involves all kinds of processes and pathways and but what are the key things maybe the top we can go for the top five things that you think we can change in our energy systems to get them to to go towards net zero emissions all of you and the five can be different as well right oh we each have to yeah or your top three okay that sounds like reason the first thing we need to do is train all of you to be energy system scientists to develop the technologies and drive the prices down you know the the thing that's that it's really clear that that the energy system both on the supply side and the demand side is going to be one of the major areas of opportunity growth of dynamics during the 21st century and one of the things that's most exciting about it is that we have a clear picture of a few things that are happening you have a very clear picture of the constraints from climate change but but many other features are really unknown what the final mix of technologies is going to be how much we can accomplish on the demand side how much integration we can accomplish what kind of a policy environment we'll work in and I think that when we when we think about solutions to the climate challenge and the energy challenge together there's there's one thing that's overwhelmingly clear is that there's not going to be a single sort of type solution and that lots of the contributions are going to come from uh relatively small things so you know I don't know if Jim Sweeney's going to speak to you guys but he gives a very compelling talk about how energy efficiency has been by far the leading source of emissions reductions today and that's that would argue that by far the second biggest source of emissions reductions has been efforts to control deforestation especially in brazil which just announced that it hit its 2022 targets this week and and then beyond that it's it's amazing how much progress is being made in terms of the supply of of non-emitting energy whether it's wind or solar or waves or biomass of the kinds of things we've been talking about I guess I'm I'm really struck at the at the range of opportunities but at the absence of a single opportunity that blows all of the others on the table okay maybe a second flavor of an answer to that question is that building on Chris's point that a lot of progress is happening in different places that can be an incredibly fun thing to not only watch and understand but to take part in so for example if we think about major areas in the world where emissions are declining it's the EU it's the US over the last decade it's certainly California we've seen intriguing leveling of emissions even in China there's huge progress in this transition I think for many of you as you'll be studying here on campus you're going to hear a lot about the California context and essentially the very quick background is that the goal by 2020 is to reduce emissions to 1990 levels that essentially has been achieved and then from 2020 to 2030 to really take a plunge and aim for 40 emissions reductions as compared to 1990 levels the simplistic California strategy or the strategy if you were to describe it simplistically could be seen as go for clean electricity generation as much as humanly possible and then electrify everything else of course the bigger picture is more nuanced than that but it's been really interesting to watch the degree to which a lot of scoping technical scenario based evaluation engineering input is going into that and really seeing what it means to pull all of these pieces together and also increasingly to bring land into that conversation in policy and planning and also to make adaptation or as California likes to call it safeguarding part of the picture as well great okay so I think I'll go back to CCS so so this conversation was about BEX you know bioenergy plus carbon capture and storage and I think our conclusion is that it might be able to contribute a billion tons per year to co2 emissions reductions which is which is a big number but of course it's not as big as we'd like but I want to talk about CCS just by itself and and carbon capture and storage can be used on on power plants it can be used on cement plants it can be used on steel plants it can be used in refineries and so forth and so there are a very very wide range of applications and and if we look at what are considered to be difficult to eliminate emissions there are about nine billion tons per year today so about 25 percent of the total emissions are actually these hard to eliminate emissions simply by renewable energy or renewable energy both storage so so that's where carbon capture and storage really can can play an important role and one of the hard to eliminate emissions are the emissions associated with providing reliable 24-7 electricity that when you Arun mentioned earlier that if you want to have eight hours of storage or 12 hours or 24 or 72 hours of storage it's absolutely cost prohibitive so trying to move to 100% renewable based electricity system you know in the next 10 or 20 or 30 years could be quite difficult and that's where carbon capture and storage can really help in the electricity sector is to provide that nighttime often typically nighttime power or that power when you have to go multiple days where it's it's not sunny or it's not windy and it turns out that there are actually two two studies which are looking at this recently that both suggest that including carbon capture and storage particularly on gas plants can reduce the cost of decarbonization significantly so just to put some numbers so in California to go from our 2020 level which is 33% renewables to to our 2030 target which is 50% renewables that it turns out that that will cost us about $250 per ton of CO2 okay that's a lot that's really that's expensive compared to other options you can do you can get more decarbonization if you use CCS on the gas plants at half the price so so that's the study that we're doing here MIT just published a study earlier this week which basically made the case on a more you know less granular basis than looking at how the California system operates and they highlighted both technologies like nuclear power you know again basically carbon-free reliable power added to the renewables that that together that mix is sort of the little cost pathway so so I just didn't want to leave the impression that since carbon capture and storage and with BEX you know with bioenergy may not you know accomplish as much as we'd like certainly carbon capture and storage has an important role to play in a low-cost solution to wrap the decarbonization great thank you so we are nearing the end of the panel a discussion here so I guess what I'm hearing is that technology and policy those two things together kind of extremely important for decarbonizing our energy system and there's no real winner right now but that advances in some kind of technology or policy so just for and on the side of policy with one last little to not discourage people I guess because I'm not familiar so much with policy so I guess what would be the first or most useful policy or set of policies that you think are needed right now or in the next decade to enable some kind of decarbonization technologies and and systems to to be put in place I've been going first on everyone go first I mean I guess in parts of the world that have been super ambitious about climate and energy and achieving the transitions that we've been talking about I think what's been interesting is to see the degree to which there have been multifaceted policy environments so here in California our cap and trade system is often referred to at present as kind of the dessert in the dinner course where a lot of the other complementary measures are pulling the weight I think a really interesting thing moving forward is really asking are these very direct pricings of carbon going to change in their relative importance and really be the big lovers whereas today it seems that when we cap carbon it ends up being cheaper and easier to reduce than we have anticipated so far yeah so that's a really difficult question because if you want if you want action now I think there's no question that technology forcing policies get action now so feed-in tariffs in in Germany made it possible to grow the PV industry portfolio standards in California have led to you know very very high penetration of utility scale renewables which reduce emissions on the other hand those kind of policies where they get you quick and immediate results and they help drive down the costs of those technologies and get to scale they run out of sort of well they get to be very costly because they are probably not the opt until technologically optimal solution and you don't give the markets any opportunity to innovate and contribute so from that perspective simply putting a price on carbon and on a price that's high enough like $40 a ton $50 a ton will send the signal and have that increase every year it's a couple percent a year that that's the kind of thing that will reach into every part of our society every part of the industry to get everybody motivated so so in the long run we need a certain price and an increasing price on carbon and in the short run you know you you need I think technology forcing regulation how you make that transition is fraught with difficulty and we see that play out in California all the time now because basically technology forcing regulation is an entitlement by a certain sector of the industry so they love them they're loathe to let them go even when they're no longer the economic optimally approach optimal approach interesting one quick sentence to close with is that I suspect most of you guys are experimentalists and policy is an area where we need to experiment as well and my sense is that what we need is a clear commitment from individuals and communities and nations around the world that the climate challenge and the energy challenge is something they're going to approach and they're going to be serious about but what we really need is experimentation with the whole range of policies that Catherine and Sally and others have talked about to figure out which ones work and which ones we can really deploy in a way that people will buy into and continue to support and strengthen through time and so I hope that you know all of you'll think about the policy aspects of the work as well as the technology aspects as things go wonderful thank you very much to all my panelists here and thank you for your time