http://theenergycollective.com/noahdeich/2193311/recap-and-commentary-national-academy-sciences-report-carbon-removal
[images and links in on-line article
Spoiler alert: "The report clearly states that the first-best option
for preventing climate change is stopping GHG emissions, and that
neither the development of CDR approaches nor the development of Albedo
Modification approaches will change this finding."]
National Academy of Sciences Report on Carbon Removal: A Recap and
Commentary
Posted February 13, 2015
Keywords: Carbon and De-carbonization, Energy Security, Tech,
Communications and Messaging, Storage, Sustainability, Utilities,
Climate, Environmental Policy, Cleantech, Renewables, Risk Management,
Energy and Economy, Fuels, News, carbon capture and storage (ccs),
carbon dioxide removal (cdr), climate change adaptation projects, energy
report
Recently the National Academy of Sciences (“NAS”) released a
comprehensive study dedicated to carbon dioxide removal (“CDR”). To
date, CDR has largely been relegated to the fringes of the conversation
on climate change, despite the fact that major reports from the IPCC and
the UN Environment Program have noted that CDR will likely be critically
important for preventing climate change. Two factors have likely
contributed to CDR’s position on the sideline for the climate conversation:
CDR solutions have historically been conflated with the
too-risky/speculative-to-even-research Albedo Modification (formerly
Solar Radiation Management) “geoengineering” techniques
Most CDR solutions cost more than other greenhouse gas (“GHG”)
abatement approaches (e.g. solar, wind, energy efficiency, avoided
deforestation, etc.), leaving little economic incentive for CDR
approaches to develop organically.
The release of the NAS report takes important steps towards reducing
both of these barriers for CDR to enter the mainstream climate change
conversation. First, the NAS released two distinct reports – one on CDR
and the other on Albedo Modification – with language explicitly stating
that these two categories of “climate interventions” should not be
analyzed together. Second, the report unequivocally endorses expanded
R&D funding into CDR approaches, in hopes that such funding will enable
the eventual commercialization of these CDR approaches.
The NAS analysis stops before identifying the necessary R&D required for
developing and commercializing CDR solutions. But this report has
hopefully cleared the way for this conversation to happen – along with
the many other mainstream policy and industry discussions necessary for
the development of CDR solutions.
The NAS study is worth the full read, but I have pulled out a handful of
key sentences and figures from the report, below, along with some
commentary on their context to the overall conversation on CDR and
preventing climate change:
The definition of CDR according to the NAS:
The NAS study defines CDR as:
“Carbon Dioxide Removal (CDR)—intentional efforts to remove carbon
dioxide from the atmosphere, including land management strategies,
accelerated weathering, ocean iron fertilization, biomass energy with
carbon capture and sequestration (BECCS), and direct air capture and
sequestration (DACS). CDR techniques complement carbon capture and
sequestration (CCS) methods that primarily focus on reducing CO2
emissions from point sources such as fossil fuel power plants.”
Under the umbrella of CDR, the NAS identifies two broad classes of CDR
approaches:
1. “Some carbon dioxide removal (CDR) strategies seek to sequester
carbon in the terrestrial biosphere or the ocean by accelerating
processes that are already occurring as part of the natural carbon cycle
and which already remove significant quantities of CO2 from the atmosphere.”
2. “Other CDR approaches involve capturing CO2 from the atmosphere
and disposing of it by pumping it underground at high pressure”
A graphic that I’ve created to understand how these CDR pathways are
related to each other and to non-CDR pathways is below:
[paths graphic]
Note 1: the NAS study includes ocean iron fertilization, which I haven’t
included in the above graphic because “previous studies nearly all agree
that deploying ocean iron fertilization at climatically relevant levels
poses risks that outweigh potential benefits.” In contrast, no other CDR
approaches in the NAS study are given that assessment, and many others
are even given endorsements on the grounds that they “can often generate
substantial co-benefits.”
Note 2: Including “Carbon Sequestration on Agricultural Lands “ as part
of a “Climate Intervention: Carbon Dioxide Removal and Reliable
Sequestration” (emphasis added) report is an important win for advocates
of soil carbon sequestration: many geologic sequestration proponents
have called into question the permanence of soil carbon sequestration as
a major issue with these approaches, which the NAS report largely
doesn’t raise as an issue.
Note 3: I have included biochar in the above graphic, but the NAS does
not, citing “literature [on biochar] is still limited, and the impacts
of utilization on net greenhouse gas emissions are not well defined.”
The NAS report unequivocally separates CDR from “Albedo Modification”
techniques…
The NAS study notes,
“Carbon Dioxide Removal and Albedo Modification (i.e., modification
of the fraction of short-wavelength solar radiation reflected from Earth
back into space) have traditionally been lumped together under the term
“geoengineering” but are sufficiently different that they deserved to be
discussed in separate volumes.”
Separating CDR from Albedo Modification has been in the works for a long
time – and I am hopeful that this report will definitively end the
discussion of whether CDR falls under the geoengineering umbrella.
The below table from the NAS report highlights a number of key
differences between CDR and Albedo Modification proposals. I have added
commentary in italics in each cell:
[graphic - CDR vs AM table]
…and links CDR as an extension of other GHG mitigation approaches.
“As a society, we need to better understand the potential cost and
performance of CDR strategies for the same reason that we need to better
understand the cost and performance of emission mitigation
strategies—they may be important parts of a portfolio of options to
stabilize and reduce atmospheric concentrations of carbon dioxide”
The report clearly states that the first-best option for preventing
climate change is stopping GHG emissions, and that neither the
development of CDR approaches nor the development of Albedo Modification
approaches will change this finding.
The report’s first recommendation is that
“efforts to address climate change should continue to focus most
heavily on mitigating greenhouse gas emissions in combination with
adapting to the impacts of climate change because these approaches do
not present poorly defined and poorly quantified risks and are at a
greater state of technological readiness.”
The report goes on to reiterate that
“there is no substitute for dramatic reductions in the emissions of
CO2 and other greenhouse gases to mitigate the negative consequences of
climate change, and concurrently to reduce ocean acidification.” And by
“helping to bring light to this topic area, carbon dioxide removal
technologies could become one more viable strategy for addressing
climate change.”
Figure 1.4 visualizes this hierarchy of desirable climate responses nicely:
[graphic - hierarchy]
The deployment of CDR techniques is limited by their cost, not by their
riskiness or likely effectiveness (as is the case for Albedo
Modification approaches).
“Carbon dioxide removal strategies… are generally of lower risk and
of almost certain benefit given what is currently known of likely global
emissions trajectories and the climate change future. Currently, cost
and lack of technical maturity are factors limiting the deployment of
carbon dioxide removal strategies for helping to reduce atmospheric CO2
levels.”
And:
“Absent some new technological innovation, large-scale CDR
techniques have costs comparable to or exceeding those of avoiding
carbon dioxide emissions by replacing fossil fuels with low-carbon
energy sources.”
The solar energy field in the 1970s provides a decent analog to the CDR
field today. That is, the potential benefits from CDR are as clear as
the potential benefits from solar were back in the 70s. But like solar
in the 70s, CDR will not be able to scale up overnight.
Only CDR approaches can generate net-negative emissions… so if we need
to deploy net-negative emissions to prevent climate change, we will need
to have viable/scalable CDR solutions.
“industrialized and industrializing societies have not collectively
reduced the rate of growth of GHG emissions, let alone the absolute
amount of emissions, and thus the world will experience significant and
growing impacts from climate change even if rapid decarbonization of
energy systems begins.”
And:
“Although such estimates of future deployment of carbon-free energy
sources indicate that it may be possible to achieve a decarbonized
energy system, great uncertainties remain regarding the implementation
of such scenarios due to factors such as costs, technology evolution,
public policies, and barriers to deployment of new technologies (NRC,
2010b)”
NAS to science funding government agencies – Part 1: more CDR R&D, please.
“Recommendation 2: The Committee recommends research and
development investment to improve methods of carbon dioxide removal and
disposal at scales that would have a global impact on reducing
greenhouse warming, in particular to minimize energy and materials
consumption, identify and quantify risks, lower costs, and develop
reliable sequestration and monitoring.”
And from later in the report:
“Developing the ability to capture climatically important amounts
of CO2 from the atmosphere and sequester it reliably and safely on
scales of significance to climate change requires research into how to
make the more promising options more effective, more environmentally
friendly, and less costly. At this early stage successful development
also requires soliciting and encouraging new synergies and approaches to
CDR. Such research investments would accelerate this development and
could help avoid some of the greatest climate risks that the lack of
timely emissions reduction may make inevitable. The Committee recognizes
that a research program in CDR faces difficult challenges to create
viable, scalable, and affordable techniques, but the Committee argues
that the situation with human-induced climate change is critical enough
(see Chapter 1) that these CDR techniques need to be explored to assess
their potential viability and potential breakthrough technologies need
to nurtured as they arise.”
NAS to science funding government agencies – Part 2: more CDR R&D from
everyone, please.
“Several federal agencies should have a role in defining and
supporting CDR research and development. The Committee recommends a
coordinated approach that draws upon the historical strength of the
various agencies involved and uses existing coordination mechanisms,
such as the U.S. Global Change Research Program, to the extent possible.”
Other notes:
Page 25: We have to remove a lot of carbon to get back to
preindustrial atmospheric CO2 concentration levels – “Reducing CO2
concentration by 1 ppm/yr would require removing and sequestering CO2 at
a rate of about 18 GtCO2/yr; reducing CO2 concentrations by 100 ppm
would require removing and sequestering a total of about 1800 GtCO2, or
roughly the same amount of CO2 as was added to the atmosphere from 1750
to 2000.”
Page 26: an interesting history of CDR
Page 31: figure 2.2 comparing fossil CCS, DACS, and BECCS.
Page 39: Not good grades given to biochar for carbon sequestration
purposes: “The residence time of biochar in situ is not well established
(Gurwick et al., 2013). Although there has been research associated with
the role biochar could play on carbon and nitrogen dynamics, the
literature is still limited, and the impacts of utilization on net
greenhouse gas emissions are not well defined (Gurwick et al., 2013).”
and “Despite not being among the CDR approaches…”
Page 57: Interesting graph showing thermodynamics of DACS vs. other
CCS approaches
Page 62: “In general seawater capture is much less technologically
mature than air capture, so research in this area could yield potential
benefits.”
Pages 72-81: Interesting summary of what characteristics of CDR
approaches the NAS committee thought were most important.
In summary and conclusion, in two quotes:
“Even if CDR technologies never scale up to the point where they
could remove a substantial fraction of current carbon emissions at an
economically acceptable price, and even if it took many decades to
develop even a modest capability, CDR technologies still have an
important role to play.”
And:
“If carbon removal technologies are to be viable, it is critical
now to embark on a research program to lower the technical barriers to
efficacy and affordability while remaining open to new ideas, approaches
and synergies.”
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