 Our next speaker is on the need for system scale models will be given by Jim Williams. Jim is a professor and the director of the energy systems management program at the University of San Francisco. The title of Jim's talk is the role of carbon management in reaching net zero and energy system modeling perspective. Over to you Jim. Thank you Sarah and thank you all for coming today. So I'm going to be talking about the role of carbon management in reaching net zero from an energy systems modeling perspective. Let me start with take home messages. I'll come back to these at the end. But first all foreseeable net zero that is net zero carbon energy systems and the United States will require technological carbon capture which I mean I think the same thing as engineered in hybrid solutions and therefore separate from the land CO2 sink. Second, that the types of carbon management require will depend mostly on the fuel strategies that are employed and I will elaborate on that. And third, that the cost of different forms of carbon management can only be accurately calculated in the context of the whole energy system. And again, I will elaborate on that. So the work that my team and I have been doing for the last 15 years or so started in California and included the deep carbonization pathways project which was a consortium of energy researchers from the 16 highest emitting countries that produced a set of reports called Pathways to Deep Decarbonization for each of those 16 countries separately and the target of both our earlier California work and the Deep Decarbonization Pathways project was meeting a global two degree C goal. Of course, what happened in the meantime was the emerging scientific consensus that even two degrees carry too many risks to the climate and the earth system and therefore that it would be very prudent to try to keep warming below 1.5 degrees C in order to minimize climate risks and of course that was that new consensus was largely catalyzed by the IPCC special report on global warming of 1.5 C and one of the key take home messages there was that remaining below a 1.5 C threshold would require reaching carbon neutrality globally by around 2050 and Rob in his opening remarks commented on the remaining carbon budget less than 500 billion tons that would be associated with maintaining temperatures below that threshold. And so our team took on a new set of research questions that were prompted by these scientific findings and by the policy responses to them. Is it technically feasible for the United States to reach net zero CO2 emissions from energy and industry by 2050? That means not including non-CO2 GHG emissions and also not including the land related emissions. Second, what is the least cost pathway to net zero given current cost forecast in sensitivities around those and then finally what is the effect of limiting decarbonization options on cost and resource requirements? And that work was published earlier this year in the article that's shown here, carbon neutral pathways for the United States and the journal AGU advances which is freely available for download at the URL that's shown on the right hand side of this figure is an example of the supplementary material. So all the documentation of additional results and methodology and so forth and running to well over 100 pages is available in the supplementary material at that website. The energy modeling was done with two state of the art tools developed by Evolved Energy Research. One is called energy pathways which is a highly detailed bottom-up energy system model and scenario analysis tool that basically divides the United States up sectorally and geographically with a high level of resolution in energy end use and energy supply equipments equipment and that are used for all forms of energy supply and end use. The second model is Rio which is an optimal capacity expansion model that encompasses electricity and also fuels and the integration of these is very important for reasons that I'll explain. So this slide shows the emissions trajectory that was followed by all of our net zero cases and so on the left hand side it shows annual CO2 for a reference case based on the Department of Energy's annual energy outlook and then labeled central there is our central scenario and you can see the black heavy line that is a straight line path from current year to a net zero at 2050 and you'll see at the 2050 time point there are some remaining gross emissions in the system and those are offset by some negative emissions and the right-hand pair of figures show the same emissions constraint in the black lines from a cumulative perspective and it shows some more detail on the composition of where the emissions are coming from and what the source of negative emissions are including primarily sequestration in durable products and to some extent geologic sequestration. The scenarios that were explored in this study as I mentioned a reference case based on the annual energy outlook which is the Department of Energy's long-term projection of population GDP and energy service demand which was used in all scenarios except for one that posited lower energy service demand through high conservation. The central case is the one that was found to be the least cost pathway to carbon neutrality. Again, all of these scenarios followed the same straight line path from 2020 to 2050. Then we did cost sensitivities with high and low fossil fuel prices and technology costs and then a number of constrained cases as we dubbed them that were exploring the effects of different kinds of policy choices and social preferences around mitigation options. So one case that limited the amount of biomass used and the amount of land available for wind and solar generation build out and also for the siting of transmission, one that explored the effect of delayed consumer adoption of electric technologies such as electric vehicles. So what if consumer uptake isn't as rapid as one might hope? One constrained the system to having no fossil fuel use whatsoever even with carbon capture and storage and no nuclear. So 100% renewable primary energy case that those restrictions would occur by 2050. In other words, no nuclear remaining by 2050 no fossil remaining by 2050. A high conservation case that I just alluded to to explore the effects of lower energy service demand and then one net negative emission scenario that is to say that the energy and industrial system itself would be a source of net negative emissions in this case negative 500 million tons of CO2 in the year 2050. And this was to follow a trajectory that was consistent with trajectories in some of Jim Hansen's work on returning atmospheric concentration levels to 350 parts per million by the end of the 21st of this century. So this shows two Sankey diagrams, which are snapshots of energy flows in the United States on the left is the year 2020. So that's basically our current energy system. And on the right hand side was our central net zero case in the year 2050. So this contrast basically the current system with what one version of a net zero system would look like. And so let me highlight some of the big changes in a Sankey diagram, the width of the lines is proportional to the energy flow. And in general, the way to look at a Sankey diagram is to see the primary energy inputs into the economy on the left hand side, the transformation processes in the middle and then the end uses on the right hand side. So one thing that you can see is that despite population and economic growth by 2050, energy use is actually significantly lower than it is at present. And we will in just a minute talk about why, what has to happen for that to be the case. The second thing to note is that the energy mix is greatly changed from on the left hand side, about 85% of primary energy in the US currently coming from the three main fossil fuels called petroleum natural gas to one in which the system is dominated by non-fossil. In this case, there is some fossil residual remaining about 15% of primary energy instead of 85%. And of course that residual amount implies something about the need for carbon management. Another obvious contrast when you look at it is the scale of the difference in electricity generation. So electricity generation is dramatically increased in all net zero cases. So the physical logic underlying the transformations that are represented in those Sankey diagrams are shown in these four pillars of a net zero or net negative energy system. So first, the decarbonization of electricity. So a 95% or more reduction in emissions intensity as by 2050 is one of the key benchmarks for such a system, energy efficiency. And so we saw a 40% reduction in per capita final energy demand which helps to explain the reduction in primary and final energy that you saw in the Sankey diagram, electrification. So a dramatic increase in the share of energy coming from electricity from about 20% today to about 50% electricity in end use plus an additional approximately 10% of energy that is coming from electric fuels, or in other words, electricity being used to produce fuels. And then finally, what doesn't show up on the Sankey diagram but is a fourth pillar of a net zero and that negative system is carbon capture and the carbon management that's associated with that. And you can see in this case, about 800 million tons per year of carbon capture was required to reach the net zero goal. Notice I didn't say carbon capture in storage. It is both utilization and geologic sequestration and in quite different proportions depending on the fuel strategies that are used. The way in brief that these four strategies are implemented is through an infrastructure transformation. And so the sectors that are shown here, electricity, on-road vehicles and space and water heating are responsible for more than two thirds of CO2 emissions from energy and industry in the United States. And what you can see is the sort of manifestation in equipment stocks of those heat sources and energy strategies. And so there's a dramatic growth in electricity capacity primarily than coming from renewable sources. There's a dramatic growth in battery electric vehicles, both light duty and medium and heavy duty and a dramatic increase in electric space and water heating, primarily heat pumps and also electric resistance. The economic consequences are shown in this slide here. So here's total annual gross spending on energy from present out to 2050. On the left-hand side is the business as usual reference case and on the right-hand side is the central net zero case. And so what you can see is a dramatic reduction in spending on fossil fuels and at the same time a dramatic increase in the spending on low carbon supplies and also low carbon demand side equipment such as electric vehicles and heat pumps. To delve into the sectoral details just a little bit, here is electricity generation on the left and capacity on the right. And there's a few steps that will be required in order to achieve the benchmarks that were alluded to earlier for decarbonizing electricity while also expanding electricity generation to meet many new electrified loads above and beyond existing electricity loads. So first a rapid transition from call which is the single biggest potential source of CO2 emission reductions in the US over the next decade. Second a rapid growth in renewable generation primarily solar and onshore wind and then a slower decline in the energy provided by gas generation and the maintenance of existing nuclear when it is safe and socially acceptable to do so. Again, this is the generation mix for our central case, the lowest cost case. And if we look on the capacity side, the other thing that is noteworthy is gas capacity being maintained for reliability. And let me explain that in the context of these daily profiles that were taken for a state in the Northeast in our analysis. So if you look first at a high wind, low load day for a Northeastern state that is dependent for its renewable sources primarily on offshore wind. So you can see the wind in the upper right hand, the wind in the blue, the solar in the middle of the day in the yellow. And then on the bottom right, then you can see the different forms of energy consumption that are associated with that output profile on the upper right. And so the excess amount of generation on that day is the pink shown in renewable curtailment. So the forms of consumption include transmission, energy storage, flexible loads, bulk loads and then large-scale industrial flexible loads and in particular electric boilers and electrolysis. These become very important to the overall economics of a high renewables electricity system. Let's look at the low wind, high load day on the left-hand side. And what we see there is because the wind is low. So you can see the blue area has greatly diminished that once storage and the other available resources are used, then the way that reliability is maintained in the system is the large dark gray area in the upper left-hand side and that's gas generation. And so the basic story that's illustrated by this figure is that the low-carbon electricity system is dominated by renewables at least 80% wind and solar across all the different scenarios that we looked at. Reliability is maintained by gas generation that is used less and less often as time goes on. And emissions constraints limit how much can be used and that the economics of the system are largely achieved through demand side measures such as large-scale industrial loads like electrolysis and dual-fuel electric boilers. That's the gas generation component. And so this repeats that point that gas capacity is maintained at roughly the current side across all the cases that we looked at. On the right-hand side, what you see is gas capacity factors. So even though you retain gas in the system, it's not operating that often and this is very relevant to one aspect of carbon management. It's in a high renewable system, gas generation with carbon capture and storage is not economic because the utilization factors for the thermal components of the system will be very low. And so adding something with very high capital costs like a CCS back in on a combined cycle or a combustion turbine really doesn't make economic sense. And so it is more appropriate either to continue to use natural gas for the relatively small number of hours in the year that are required for reliability's sake or to use some form of decarbonized fuel, which also is a carbon management question. Now, in terms of sort of a broad brush description of what the decarbonization is, what the decarbonization strategies are, in the early years of the next decade in particular, the opportunity for emissions reductions is largely an electricity and largely associated with the factors that I described earlier, the retirement of coal by 2030 and the rapid build out of renewables. And then later on in this 30-year time period, reductions will be coming from two sources. One, the electrification of end uses. It takes a while for those reductions to be manifest because these are large equipment stocks, so vehicles, heating and cooling equipment and buildings and so forth that have long lifetimes. And so for that stock to turn over, even if that process gets started very rapidly now, if they're retired on natural lifetimes, then it's going to take a while for the emissions reductions from replacing fossil fuel with low-carbon electricity to be manifest. And the other aspect that also will eventually need to be realized is for residual fuel uses that those fuels will also have to be very low carbon. And that entails carbon management strategies. So basically electricity in the short term and fuels in the long term. So there are three sources of fuels and a carbon neutral system. So about 50% of final energy demand in 2050 continues to be fuels. Now of course the total amount of final energy demand has decreased as I mentioned due to energy efficiency that includes the inherent energy, thermodynamic efficiency of electrification, the superiority of electric drive trains over internal combustion for example, no Carnot limit to deal with. But of what remains about 50% is fuels and there can be three sources basically, fuels that are derived from electricity including hydrogen and hydrocarbon fuels synthesized from the hydrogen that's produced by electrolysis on a carbon source. Second is fuels derived from biomass mostly indirectly produced through processes like gasification and pyrolysis and Fisher tropes. These are designer fuels basically a new generation of biomass based fuels not corn ethanol. And then finally fuels that are derived from petroleum or natural gas using carbon capture either in fuel production or offsetting of emissions. And one thing I should mention with regard to the 50% of final energy demand remaining fuels that a lot of that remaining amount is for feedstocks. And unless we don't need hydrocarbon feedstocks then there's going to have to be sources of hydrocarbons and these are the basic sources coming back to another set of psyche psyche diagrams this sorts this illustrates the scenarios that we looked at that had the highest and lowest residual fossil fuel use so bookends if you will on the left side is the central case but with a low fuel price sensitivity there is more petroleum and natural gas remaining in that case than in any others and on the right hand side the 100% renewable primary energy case which by definition had no remaining fossil fuel in the system so again these are 2050 SAP shots so let me show you the implications of that for carbon capture utilization and storage. In the 100% renewable primary energy case carbon capture is still required and that's illustrated in the highlighted figure. This is maybe a counterintuitive outcome for some why would you need carbon capture if you don't have fossil fuels in the system but as I said earlier if you have hydrocarbon demand even if you don't have fossil fuels you need to manage that CO2 and if there are limits on biomass which was one of the assumptions of our study that there's a sustainability limit to how much biomass can be used then there's going to need to be carbon capture in order to provide the carbon input combined with hydrogen from electrolysis to produce gas and liquid fuels. The other extreme or book in case is the central low fuel price case that had the highest residual fossil fuel emissions and so that's shown here in this case the majority of the capturing hydrogen the vast majority is sequestered geologically and so you can see that the level of carbon capture is of a similar order of magnitude in these two otherwise very different cases and then in the central case there are roughly even numbers of associated with sequestration and with utilization in terms of the sources this is illustrated in the central case here the majority of the carbon that's being captured is coming from biomass so I mentioned earlier that power plants with carbon capture are not particularly economic and that applies to BEX power plants as well as it does to conventional fossil fuel power plants. The utilization rates in a high renewable electricity system were not very high. The place where BEX is occurring in the systems that come out of our optimization is actually in the fuel supply sector so basically biofuel refineries have very high utilization in such a system and those would be the places where you would apply carbon capture and where you could have sort of integrated utilization and or sequestration located potentially in a complex fuel refining complex so geographically concentrated and then you can also see similar sources of carbon in the central low fuel price case. In that case there is where the fuel prices are low enough and then you do start to see some economic CCS generation and that's the yellow bar fairly small bar representing electricity here. Alright so fuel production carbon management is illustrated here we don't have time to go into detail but it does show that there's actually quite a bit of variety in the fuel strategies that are implied by the constraints that I refer to when describing the different scenarios and so if you take a look at for example under hydrogen in the low land case then you will see that because land is constrained for solar and wind generation then the amount of electrolysis which is basically using that solar and wind generation for its production is lower and so the lowest amount of hydrogen production is occurring and renewable siding is constrained so that's just one example if you look under biomass then you will see that under the delayed electrification case you have the highest production of biomass which is a somewhat counterintuitive result perhaps that with delayed electrification maybe it's not counterintuitive but delayed electrification you need more fuels and so that is the case that puts the highest demand on biomass resources and so forth so these are just some quick examples of what we know and how we can anticipate the effects of different kinds of constraints and policies on fuel production outcomes but basically at this stage all we are saying is there are physically plausible outcomes but it's going to take R&D, piloting market experimentation and information fortunately if we follow the trajectory that I described earlier with doing the things that we know that we have to do over the next decade in terms of decarbonizing electricity electrification campaign on transportation and buildings there is time potentially to work out the combined fuel and carbon management strategy because these are deeply related in fact sectoral coupling is extremely important in all cases so let me come back to the take home messages that I started with the U.S. technology systems in the U.S. will require technological carbon capture unless somehow there is breakthroughs where we no longer need hydrocarbon fuels and feedstocks for everything from aviation to plastics production or unless the sustainable biomass resource potential for the next generation of scholars in this area. Second, the types of carbon management required will depend on the fuel strategies employed and that includes the relative shares of fossil biomass and electricity derived fuels and whether the use of those So in other words, highly concentrated sources, for example, a cement plant, as opposed to very diffused sources where carbon capture is not logical, such as aviation, and where therefore if you continue to use a fossil source for your fuel then you would need to have some kind of offsetting. And third the societal force costs to the different forms of carbon management can only be accurately calculated in the context of the whole energy system because the cost of the energy inputs to carbon capture will depend on the electricity mix and the coupling between the fuel and electricity sectors. Okay, last two slides here, just comment on negative emissions, negative emissions are uncertain and decline under business as usual. The BAU projection of the land sink is probably that it is declining and the outlook for CO2 capture transport and storage is quite uncertain and therefore it is not clear exactly where the BAU carbon management situation is taking us and in order to increase negative emissions is going to require the kind of research and development that's being discussed here at this meeting. And this final slide is that realism about the use of negative emissions should this extend beyond the current argument which is largely about moral hazard so the vacuum left by federal in action is created a balkanized system of state cities and exploration that are pursuing net zero emissions separately, sort of a Russian doll approach for each component of the system separately achieves net zero this is inefficient. Second, achieving net zero is primarily an infrastructure problem not an accounting problem. Many negative emission strategies require counterfactuals that is baselines which open up the possibility of rent seeking behavior. And finally, this is my main take home message, negative emission opportunities are themselves physically limited. All scenarios that achieve net zero have at least a two third reduction and gross emissions you cannot basically direct air capture of offset your way out of very dramatic changes in the energy system and so from a company standpoint of business standpoint they should look to reduce gross emissions first through the pillars of clean electricity electrification and efficiency. And also be aware that many negative emissions categories may already be oversubscribed or run the risk of being double counted. Thank you. Great. Thank you so much. Excellent. We've got a number of questions for you on the couple minutes. So I'll pose a couple. The first one is from a tool area. What do you see is the most critical milestones by 2030 for the US to get to net zero by 2050. Glad you asked. Here's a graphic was put together by our colleagues at Berkeley lab. So, these are the, what we consider to be the key 2030 milestones, increasing solar and wind capacity by a factor of three to four to about 500 gigawatts. It's about 150 now, eliminate basically all generation from call 1% or less, maintain the current gas generating capacity for reliability for the reason that I says that doesn't mean continue current gas generation at current levels that's that's a different story. This is capacity increase the zero emission vehicle share and the heat pump share of sales to 50% by 2030. That doesn't mean that the stocks are 50%. It means that sales are that all new buildings and appliances should meet the strictest energy efficiency goals possible that we invest in research and development for carbon capture sequestration and carbon neutral systems. And then finally, we, we start the infrastructure build out for electricity transmission which is notoriously slow in the United States, and also begin to anticipate other kinds of pipeline needs and a decarbonized economy. Okay, I'm going to ask one more question. This is actually a merge of questions that came in from Stephanie our host and Sally Benson. You've mentioned there's going to be a lot of CO2 utilization compared to sequestration. What will all the CO2 be used for and is the technology available for today and how much does it cost to use it scalable. So this is looking across all of our cases. So the point that I made about the carbon capture side was that in some cases there is the capture carbon is primarily geologically sequestered. And in other cases it's primarily utilized and you see on the bottom row here that represents all of our different scenarios, the wide variety of that's involved. If you look at the legend, you can see that the primary utilization use is in power to liquids with only a little bit of power to gas from a quantitative standpoint, what that means from a sort of infrastructure standpoint is that you have plants probably where there's co-location of fuel production and renewable generation so that you can take advantage of local hydrogen production and also a local carbon source. So this is speculative, but it strikes our team that a future development where you have say an offshore wind complex or a sort of desert solar complex where you'd have very high capacity factor renewable generation and therefore high utilization of hydrogen production, if that could also be co located with the fuel synthesis that takes that hydrogen with a carbon source and produces fuel that that might be a very economically preferable outcome kind of similar to what happened with electricity the deregulation in the late 1980s where lots of gas generating plants were built very close to where electric transmission lines crossed natural gas pipelines so it's not the same situation but maybe analogous.