[CDR] From Zero to Hero?: Why Integrated Assessment Modeling of Negative Emissions Technologies Is Hard and How We Can Do Better #net

Ron Larson


This topic started on this list on 2 April.  There has been a nice dialog on the CDR list, which was a second recipient.  This is in part to bring this biochar list up to date on the subject of SDGs - but also to alert the list to several exciting mainly-biochar papers that point out how biochar yields can be increased by generating biochar where the input biomass has been pre-mixed with ash.   This is not the same as using a mix of char and ash coming out of a power plant.   The three papers are all from 2019 by UK biochar experts - with one that is non-fee.  

All their work claims to be new and promising for biochar.   Anyone have comments on this  - or on the SDG side of the dialog below?


Begin forwarded message:

From: Ronal Larson <rongretlarson@...>
Subject: Re: [CDR] From Zero to Hero?: Why Integrated Assessment Modeling of Negative Emissions Technologies Is Hard and How We Can Do Better
Date: April 12, 2020 at 7:36:43 PM MDT
To: Andres Clarens <afc7r@...>, Carbon Dioxide Removal <CarbonDioxideRemoval@...>
Cc: Jay Fuhrman <jgf5fz@...>, Benoit Lambert <benoit.lambert@...>, Andrew Lockley <andrew.lockley@...>

Andres and ccs

Thanks for this very thorough reply.    I respond a bit below, and intend to make a more complete response to the biochar list, where this thread first appeared .

See inserts below

On Apr 8, 2020, at 6:42 PM, Andres Clarens <afc7r@...> wrote:

Hi everyone, 

I’m the corresponding author on this paper and would be happy to answer questions you all have. I’m also cc’ing Jay Fuhrman, a graduate student in my lab and lead author on the paper. 

I apologize for not chiming in sooner. I receive the CDR emails but 1) many of the notes get caught in my spam filter and 2) I’ve been managing the fact that my lab is temporarily shut down (half our group is experimental), teaching online, as well as the normal deadlines. 

A few quick replies to some of the points raised below: 

- Our statement that NETs other than BECCS don’t have value outside climate mitigation needs to be interpreted from the perspective of IAMs. IAMs in general have  sophisticated energy systems modeling capabilities with lower fidelity hydrology, crop, industry, etc. models. Biochar clearly has co-benefits that are important and so do many of the other NETs and that is why we wanted to provide this qualitative framing in the context of SDGs. But GCAM, the IAM with which I am most familiar, would need a lot of work to capture the co-benefits to ag yields, water quality, etc. This work is necessary and important, but hasn’t been done yet. This paper is intended to highlight some of those gaps - not to disparage biochar in any way.
[RWL1:   Agree with this point - which was not a concern.  It is very logical that IAM developers would use BECCS over biochar.  From an IAM perspective,  BECCS must be orders of magnitude easier to use in a model.

- The reason we wrote that BECCS and biochar are coupled is that doing either of these things at Gt/yr scale would probably require that the activities be coupled in some way. My understanding is that ag residue and sludge etc. will quickly be exhausted as sources of biochar and we will need to build BECCS plants that can produce some heat and some biochar as a byproduct. Papers like this one influenced our thinking here. But we would love to learn more about this. 
[RWL2:  “this one”  is:   "Synergies between BECCS and Biochar—Maximizing Carbon Sequestration Potential by Recycling Wood Ash’” by Buss et al. at 
Unfortunately behind a pay wall, so it took a while to get.  

And then I found that it was preceded by its ref. #26
"Unexplored potential of novel biochar-ash composites for use as organo-mineral fertilizers"

Also it was followed by

"Potassium doping increases biochar carbon sequestration potential by 45%, facilitating decoupling of carbon sequestration from soil improvement    Similar author team, also 2019, found at

     I just found this last, which IS available on a non-fee basis.   The concept of firing biomass with ash was new to me - and seems well justified by a team that is skilled in biochar analysis.   I could not confirm all the details, but t think this biochar-skilled team is making a new important point, advancing biochar in the sense of the Fuhrman-Clarens paper of this message.  I now see the connection between BECCS and biochar as one where biochar is benefitting BECCS rather than the reverse.  That is, biochar is able to take ash off the hnands of any facility combusting biomass.  There are a huge number of facilities around the world combusting biomass (and almost none then trying to sequester captured CO2 deep underground).  And all (?) have a problem with ash disposal.  
On the USBI board, Josiah Hunt has talked of purchasing and encouraging the production of biochar from biomass-powered electric generating stations in California.  It comes with ash as the operators simply shorten the time for the ash to be ejected - giving more pyrolyzed biochar material at a relatively low cost.  This is not the same as the Buss et al team's work, but it shows that BECCS is not a key part of this proposed new biochar-ash production activity.

- We are not definitely experts in biochar, nor do we claim to be. But we also don’t have any particular agenda regarding biochar or any of the other technologies included here. Our objective was simply to highlight some ways in which the integrated modeling community might better model a suite of technologies. Right now they are betting the house on BECCS and afforestation alone, and that’s a problem. 
[RWL3:   You were very clear on this big problem for the BECCS promoters - even independent of its low scores when the SDGs are part of the decision process.`

- Ronal’s point by point discussion of our rating effort is much appreciated. I have no doubt that if we had used an expert elicitation process we could have come up with a figure that would be more refined than this one but our figure is meant to be a first overture and will hopefully help stimulate discussion and refinement as you all are doing here. 
[RWL4:   I hope I made it clear that I thought your team had made a major positive suggestion as to how the CDR approaches would benefit from including the 17 SDGS.   I hope still that other car list participants will jump in on the SDG scoring specifics.

I have no problem with your team using only the 5 integers -2, -1, 0, +1, +2 as a starting point, , but hope that others will attempt a finer graduation.

In my opinion, one of the biggest lessons I learned writing this paper was that modeling the true potential of any soil-based approach to mitigate climate at a global scale is very difficult but very necessary. If any of you have a desire/interest to work on some of this, I’d be excited to discuss. It’s not a direction our work is heading now, simply because we aren’t experts in this space, but I am happy to discuss where we see opportunities.
[RWL5:   A nice offer.   I’m sure that I can find plenty of good biochar “volunteers”, when you and your students are looking for combined biochar-soil-CDR expertise.  My guess is that of the several hundred new biochar papers appearing every month - about 90-95% are soil related (always CDR relevant - but usually not even mentioning CDR).  Your type of expertise can help soils assume a larger role in IAM and CDR circles.  The three Buss biochar papers above would all benefit from having more SDG flavor - and vice-versa.

Thanks again for the really interesting conversation. I look forward to discussing more. 
[RWL6:   Again,  apologies for this delayed response - it was a great surprise to learn how significantly “waste” ash could modify biochar production.   This is totally separate from SDGs and BECCS - but one more plus for your paper.  So, I hope that in future advances of your paper, we can read that BECCs is best thought of as benefitting from biochar - not as in your Figure 5.  And of course, that biochar is also NOT sufficiently the same as SC = Soil Carbon - and has its own column - befitting the approach leading the CDR pack (as said in the third cite above).



Andres Clarens
Associate Professor, Engineering Systems and Environment
Associate Director, Environmental Resilience Institute 
University of Virginia
P (office) 434-924-7966
W (eri) 

On Apr 8, 2020, at 2:32 PM, Ronal Larson <rongretlarson@...> wrote:


Good to see your reactions!  

But first a few more background items.  We call this a "Fuhrman” article, but we should note the Corresponding author is Professor Andres Clarens.  A good background for this article at .  No reason to expect extensive knowledge of biochar by this group.  I agree that there could have been better reviewing on the part of the Journal - by getting a review from expertise in all eight of the listed NET/CDR approaches (which probably would  have resulted in biochar earning a column by itself - my main complaint). In that regard, I read an article today claiming 16,000 biochar articles as of 2018!  It wouldn’t surprise me to learn that is about half of the total for the NETs arena - so shouldn't that (possible) factor of 1/2 make biochar worthy of a column by itself? (And new biochar articles coming at about 250 per month!)

Few inserts below.

On Apr 8, 2020, at 5:29 AM, Benoit Lambert <benoit.lambert@...> wrote:

While I agree with you ranking using sustainable development goals (SDG) is an appropriate methodological used in this article, the attributed marks show little understanding of biochar, as very well expressed in your own re-marking and comments below. How in the world could « an unfortunate typo » assimilate biochar with BECCS? How could such an error be maintained in Figure 5 as it did… 
[RWL1:  Again - I view this as a useful article mainly because it combines IAMS, NETs and SDGs (I think for the first time).  Some editing goof that ties BECCS and biochar together isn’t that big a deal on this CDR list, and hopefully can be used for a correcting note somewhere.

What about: the authors do not master soils-based solutions... It appears so when they write "The second difficulty with NETs and the standard model of directed technical change is that many NETs have no value except for their contribution to lower GHG concentrations. These are not substitutes for some other way of producing goods. While R&D investment is required to bring NETs costs down, their use never becomes less dependent on the GHG price, as is the case with renewables replacing fossil fuels. » They should know biochar as numerous co-benefits besides lower GHG, and should have written about it. 
[RWL2:   I too found that to be surprising - but decided that their term “many NETS” was correct - and aptly applied to their four right hand columns (which received the low SDG scores).  As to their not having written about biochar co-benefits - I think the relatively high scores for the “biochar” column (in quotes because there isn’t one), affirm their understanding that biochar IS different from BECCS and the others in the right-hand-group.  Your and my difference from the authors is in the numerical scores and the failure to give biochar a separate column.  Biochar DOES have similarities to the category called SC - but so does biochar have similarities to Blue Carbon and afforestation.
I wouldn’t worry about their writing on any of the specific NETs - they described who they were citing (who did NOT combine biochar with anything).

Their description of biochar is almost non-existant. They mention the return of biochar's carbon to the atmosphere, in fact very marginal in biochar literature — and do not mention terra preta recalcitrant to decomposition after milleniums. It gives the impression they know very little about biochar. The insistance in the literature on BECCS and DACs, two no-existant technologies in the real world, is simply mind blowing. The fact they give no mark to SDG on education for biochar tells a lot, the authors do not see biochar is a great example of bio-mimicry. 
[RWL3:    I have yet to see ANY article that attempts to compare the 8 (in this article) NETs that does a good job in describing them all.  These 8 NETs are too diverse - and probably biochar is the most diverse of all - hence hardest to describe accurately.  One can see the biochar difficulty in its wide range of overlap with so many SDGs. 
To repeat - to treat biochar equitably, the 17 SDGs provide a good outline for discussion - and too rarely attempted.

Again, thanks for your strong interest in this topic - and especially for pointing out biomimicry.


Le 7 avr. 2020 à 08:06, Benoit Lambert <benoit.lambert@...> a écrit :

Wow this is very interesting stuff! Thank you Ronal for the amazing constructive criticism. Just when I am preparing a blog on Drawdown Review ranking of nature-based solutions, in particular biochar — I think they should be way on top, for their innovative character. I will finish reading Fuhrman et al including the supplement, and, publish my blog. Biochar is wildly underestimated, even if now recognized. For example, evaluations do not consider organic waste as a world problem… well it is. We have to slow down Earth’s exhaling, that is one of the tools in our CDR toolbox. 
Kind regards, 

Le 6 avr. 2020 à 19:45, Ronal Larson <rongretlarson@...> a écrit :

Andrew and list:

This is to comment on the “Fuhrman” article you identified last week.  I am here initially exactly repeating comments sent to the IO list “Biochar”.   I have had only one reaction there - mostly agreeing with the comments below (there are few biochar enthusiasts paying much attention to IAMS, or interested in comparing biochar to the alternatives of this paper, I’m afraid).  

At the end,  I add some new additional broader thoughts.

I found this paper to be  supportive of biochar.  These cites work for the full non-fee article (sort of) comparing biochar to its CDR competitors.

 I generally approve of their effort, but think their methodology could be improved.  
a.  They lumped biochar with SC = Soil Carbon;  the only paired combination.  I think this negatively influenced biochar’s ratings (for example SC provides no energy).
b.  Numerical values are given to a majority of the 17 SDGs (= Sustainable Development Goals), but no description of how the votes were determined (who, after what sort of dialog, etc).
c.  No recommendation on how decision-makers should use their rankings (which were to range from -2 to +2.)
d.  The rankings were coarse - for the favorables, most often a 0 or 1 (with only “Blue Carbon" getting 7/12 “2’s”;  the SC/biochar combo had 11 “1’s and one “0”; with 5 SDG’s receiving no votes.). Below I add a decimal point, and comment on all 17 SDGs.  I add rationales for my votes - that are more detailed than theirs.  I tried to keep my rationales short and would be glad to expand on any.
e.  To get a better understanding, you’ll need to also go to the supplemental - but I give below everything that is there for biochar (but not the other CDR approaches, where I claim no expertise.). There is little comfort there for our “Non-bio” competitors (especially BECCS).

This is to ask for your comments - after which I will respond to the CDR list.    So here is my version of the “SC/biochar” column of their Supplemental.  Where I refer to two others to the lest, they are “Blue Carbon” and “Afforestation”. (Both of which could have a biochar aspect as well.). My additions are all in bold.  I have no “2’s, but I get close.

 #1.  No Poverty    “Healthy soil can produce more food and goods, they contributing positively to food security and incomes for the world’s poorest people” ‘For SDG 1, No Poverty, reducing costs and dependency on external resources together with the increase in crop productivity would help farmers to be self-sufficient while increasing incomes.”(Smith et al., 2019).             Score: 1.    RWL proposed score: 1.8,  based on biochar being available to so many of the poorest through cooking and heating.   The two others could be raised a little.

#2.  Zero Hunger.         Healthy soil can produce more food and goods, thereby contributing positively to food security and incomes for the world’s poorest people.. food security will benefit from higher yields and higher agro-ecosystem resilience (Smith et al, 2019).         Score: 1.   RWL proposed score: 1.9,  based on roughly tripled NPP in Terra Preta soils (after centuries).  Would raise the other two a little.

#3.  Good Health & Well Being.    “by increasing crop yields, aiding soil remediation and water purification, [soil carbon enhancement] and biochar application to soils can contribute significantly to peoples’ nutritional health”. (Smith et al., 2019).           Score: 1. RWL proposed score: 1.8,   based on #2 rationale.   And scores of 2 & 1 to the left could be raised.

#4.  Quality Education.    No score given in paper.    RWL proposed score: 1.5 , based on the complexity and novelty of analyzing biochar (covers so many topics - both in the social and physical sciences).

#5.  Gender Equality.  No score given.  RWL proposed score: 1.9, based on personal experience in world of third world charcoal-making cook stoves.  Also can be great gender equality benefit in agricultural field work.

#6. Clean Water & Sanitation      Reduced soil erosion. (Smith et al., 2019)              Score: 1.   RWL proposed score: 1.8,  based on dozens of papers every month on both of these two topics.  Also scores of 2 and 0 to left.   Much more here than erosion control.

#7.  Affordable and Clean Energy     “give people access to Affordable and Clean Energy (through energy crops).” (Smith et al., 2019)             Score: 1. RWL proposed score: 1.7,  based on having centuries of out-year benefits compared to BECCS, which also received score of 1 (the only two NETs’s with. positive scores)   Biochar is the only CDR approach I have ever seen quoted as having negative costs (possible with cook stoves) because of what happens for centuries  AFTER biochar is placed in the soil.

#8.   Decent Work and Economic Growth   Through the combination of improved agricultural productivity,  improved water and air quality, and the potential of soil (organisms) to provide medicines, SCS can contribute positively to SDG 3, Good Health and Well-being. This may also help to achieve Decent Work and Economic Growth and Industry” (Smith et al., 2019).                Score: 1.  RWL proposed score: 1.8, based mostly on much greater (full time) job opportunities than the two to left.  Good place also to mention low risk for investments. 

#9.  Industry, Innovation and Infrastructure.     Biochar could provide carbon negative energy with value-added co-product. More resilient soil can dampen the effect of climate hazards (Smith et al., 2019)                   Score:1.    RWL proposed score: 1.7, based on blue carbon score of 2.  Also huge number of monthly biochar papers in these three “I”  areas.

#10.  Reduced Inequalities      Not directly impacted by SCS or biochar (Smith et al., 2019), but global carbon market could provide means of financing sustainable agriculture in the developing world      (Author assessment)                  Score: 0.    RWL proposed score: 1.6, based on score of 1 given to Blue carbon.  This argument much like that for SDG 5 on gender equality.   Note the Smith statement relates to SCS - not biochar.  This the only zero given for biochar - which doesn’t fit with the biochar literature.

#11.  Sustainable Cities and Communities      “This may also help to achieve Decent Work and Economic Growth and Industry, Innovation and Infrastructure, which in turn might contribute to developing Sustainable Cities and Communities” (Smith et al., 2019)           Score: 1.    RWL proposed score: 1.6, based in part on blue carbon receiving a score of ‘2’.  But also Stockholm is having good success with biochar.  Cities aren’t going to be the main biochar target, but for most cities,  biochar seems the most likely NET.

#12.   Responsible Consumption and Production.     Carbon markets could offer pathway to finance more sustainable agriculture. (Smith et al., 2019).        Score: 1    RWL proposed score: 1.6,  based in part on score of 2 for blue carbon.  But also especially the role of biochar in improving forest health.

#13.   Climate Action.    “All NETs positively contribute to SDG 13: Climate Action by removing CO [sic] from the atmosphere, coinciding with the sequestration potential of each NET.’     No scores provided, but the totals are certainly different and sums and averages could have been given.).  RWL proposed score: 1.7, based roughly on my  16 other SDG scores.   Some biochar activities already receiving funding in this category.  

#14.  Life Below Water.     “SCS can help to prevent erosion and polluted substances from reaching water bodies.” (Smith et al., 2019).    Score: 1.   RWL proposed score: 1.6, based in part on blue carbon score of 2.  Numerous biochar papers on biochar’s capability to retain phosphorous and other pollutants.  Can help with ocean acidification.   Note Smith quote is only on SCS.

#15.   Life on Land      “SCS can help to improve soil health, thereby enhancing potential for biodiversity and healthy ecosystems.” (Smith et al., 2019)      Score: 1.      RWL proposed score: 1.6, based in part on blue Carbon having a “2” score.   But also biochar seems to be the only way to reclaim land that has no possible present use.  Many papers on biochar for mine-land reclamation.  Also many biochar papers on reducing fire hazards due to forest over-growth.

#16.   Peace, Justice and Strong Institutions      Not scored.    RWL proposed score: 1.7,  based in part on the likely control of biochar installations at the local level, if needed at all.  Most risk is to the land owner, who can easily do prior testing.

 #17:    Partnerships for the Goals.     Not scored.   RWL proposed score: 1.6, based on the wide range of environmental and societal problems (other than climate)  being addressed in the several thousand annual biochar papers.   This SDG is a catchall - where biochar fits, even if other NETs do not.

      End of my comments on the Supplemental scoring.  Thanks in advance for any comments. 


Additional comments of 6 April - intended now to be more on CDR use of this material - and not on biochar.

a.   I think the paper’s emphasis on SDGs to be new and most laudable - and so hope CDR list-members interested in other of the paper’s rankings will chime in with their own rankings.  This request especially to those working with CDRs ranked low.
b.  I hope someone can tell us how the rankings were developed (not needing names, just the procedures - and especially how many “jurors" and what sort of debate took place).

c.  I can foresee that future funding for the CDR approaches of this paper, especially if from UN-related groups, might have to formally address the SDGs.   And if they don’t do that well, their chances of funding would go down.  For instance,  researcher’s might be told that x % of their proposal scoring would be based roughly on this paper’s methodology - solely to ensure that the proposers were seriously thinking about ALL the SDGs, not simply (for instance) #13 - Climate.   We on this list should welcome that - as it should help justify and increase CDR expenditures  

d.  For those not too familiar with the CDR approaches, I need to alert that biochar is NOT part of BECCS - as is shown in their Figure 5.  An unfortunate typo, since BECCS is ranked so poorly.


On Mar 31, 2020, at 1:28 PM, Andrew Lockley <andrew.lockley@...> wrote:

From Zero to Hero?: Why Integrated Assessment Modeling of Negative Emissions Technologies Is Hard and How We Can Do Better

  • 1Department of Engineering Systems and Environment, University of Virginia, Charlottesville, VA, United States
  • 2Joint Global Change Research Institute, University of Maryland and Pacific Northwest National Laboratory, College Park, MD, United States
  • 3Department of Environmental Sciences, University of Virginia, Charlottesville, VA, United States
  • 4Batten School of Leadership and Public Policy, University of Virginia, Charlottesville, VA, United States

Climate change mitigation strategies informed by Integrated Assessment Models (IAMs) increasingly rely on major deployments of negative emissions technologies (NETs) to achieve global climate targets. Although NETs can strongly complement emissions mitigation efforts, this dependence on the presumed future ability to deploy NETs at scale raises questions about the structural elements of IAMs that are influencing our understanding of mitigation efforts. Model inter-comparison results underpinning the IPCC's special report on Global Warming of 1.5°C were used to explore the role that current assumptions are having on projections and the way in which emerging technologies, economic factors, innovation, and tradeoffs between negative emissions objectives and UN Sustainable Development Goals might have on future deployment of NETs. Current generation IAM scenarios widely assume we are capable of scaling up NETs over the coming 30 years to achieve negative emissions of the same order of magnitude as current global emissions (tens of gigatons of CO2/year) predominantly relying on highly land intensive NETs. While the technological potential of some of these approaches (e.g., direct air capture) is much greater than for the land-based technologies, these are seldom included in the scenarios. Alternative NETs (e.g., accelerated weathering) are generally excluded because of connections with industrial sectors or earth system processes that are not yet included in many models. In all cases, modeling results suggest that significant NET activity will be conducted in developing regions, raising concerns about tradeoffs with UN Sustainable Development Goals. These findings provide insight into how to improve treatment of NETs in IAMs to better inform international climate policy discussions. We emphasize the need to better understand relative strength and weaknesses of full suite of NETs that can help inform the decision making for policy makers and stakeholders.

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