Direct Air Capture (of Carbon Dioxide)

[KiwiGriff]

 So I'll believe it when the first few dozen million giga tons.
CCS is an excuse to do nothing based on the creation of an as yet unknown technology in the future.
AKA.
Magical thinking.
The amount of air you would need to pump past any industrial type extraction method makes the idea absurd.
Even using natural methods like old growth forestry rely on mind boggling amounts for far too much time .
 

[sidd]

CCS (carbon capture and sequestration) only addresses exhaust from present fossil carbon burn. I am speaking of drawdown.  Besides, CCS has another thread.

Another point is that the interests of equity demand that the nations that burnt the most fossil carbon in the past ought to drawdown the most in future. Alas, that is probably not going to happen.

sidd

[KiwiGriff]

I Apologize  sidd .
I had the term wrong.
I meant the draw down of atmospheric CO2 being impossible with present technology at a palatable  economic cost.

[Ken Feldman]

I Apologize  sidd .
I had the term wrong.
I meant the draw down of atmospheric CO2 being impossible with present technology at a palatable  economic cost.

I think the term that is being used is "Negative Emissions Technology" abbrievated NET. The linked paper provides an overview of the current status of NET.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsta.2016.0447

Negativeemissions technologiesandcarbon captureandstoragetoachieve theParisAgreement commitments
R.StuartHaszeldine,StephanieFlude,Gareth JohnsonandVivianScott
SchoolofGeoSciences,UniversityofEdinburgh,Edinburgh,EH93FE, UK RSH,0000-0002-7015-8394

How will the global atmosphere and climate be protected? Achieving net-zero CO2 emissions will require carbon capture and storage (CCS) to reduce current GHG emission rates, and negative emissions technology (NET) to recapture previously emitted greenhouse gases. Delivering NET requires radical cost and regulatory innovation to impact on climate mitigation. Present NET exemplars are few, are at small-scale and not deployable within a decade, with the exception of rock weathering, or direct injection of CO2 into selected ocean water masses. To keep warming less than 2°C, bioenergy with CCS (BECCS) has been modelled but does not yet exist at industrial scale. CCS already exists in many forms and at low cost. However, CCS has no political drivers to enforce its deployment. We make a new analysis of all global CCS projects and model the build rate out to 2050, deducing this is 100 times too slow. Our projection to 2050 captures just 700 Mt CO2 yr−1, not the minimum 6000 Mt CO2 yr−1 required to meet the 2°C target. Hence new policies are needed to incentivize commercial CCS. A first urgent action for all countries is to commercially assess their CO2 storage. A second simple action is to assign a Certificate of CO2 Storage onto producers of fossil carbon, mandating a progressively increasing proportionofCO2 tobestored.NoCCSmeansno2°C.

I think that the conclusions are pessimistic given that renewables are rapidly replacing fossil fuels, so CCS won't be needed for existing fossil fuel infrastructure.  However, the best IPCC scenario, RCP 2.6, requires the deployment of NET to reduce carbon concentrations in the atmosphere.

One of the promising NETs available today is biomass burning with CCS.  Production of biochar with CCS is also a promising NET that could provide for soil restoration (helping improve that carbon sink) as well as biofuels for industrial feedstocks and aviation.  While those last two aren't negative emissions, they're at least carbon neutral and will allow us to completely transition off of fossil fuels.

[Ken Feldman]

Here's another study of Negative Emissions Technologies (NETs) that indicates more rapid deployment of renewable energy as well as reductions in methane emissions can reduce, but not eliminate, the amount of NETs that need to be deployed.

http://atoc.colorado.edu/~whan/ATOC4800_5000/Materials/CC_policy_renewable.pdf

Alternative pathways to the 1.5 °C target reduce the need for negative emission technologies

Detlef P. van Vuuren   1,2*, Elke Stehfest1, David E. H. J. Gernaat1,2, Maarten van den Berg1, David L. Bijl2, Harmen Sytze de Boer1,2, Vassilis Daioglou   1,2, Jonathan C. Doelman1, Oreane Y. Edelenbosch1,2, Mathijs Harmsen1,2, Andries F. Hof   1,2 and Mariësse A. E. van Sluisveld1,2

Mitigation scenarios that achieve the ambitious targets included in the Paris Agreement typically rely on greenhouse gas emission reductions combined with net carbon dioxide removal (CDR) from the atmosphere, mostly accomplished through large-scale application of bioenergy with carbon capture and storage, and afforestation. However, CDR strategies face several difficulties such as reliance on underground CO2 storage and competition for land with food production and biodiversity protection. The question arises whether alternative deep mitigation pathways exist. Here, using an integrated assessment model, we explore the impact of alternative pathways that include lifestyle change, additional reduction of non-CO2 greenhouse gases and more rapid electrification of energy demand based on renewable energy. Although these alternatives also face specific difficulties, they are found to significantly reduce the need for CDR, but not fully eliminate it. The alternatives offer a means to diversify transition pathways to meet the Paris Agreement targets, while simultaneously benefiting other sustainability goals.

[Tom_Mazanec]

Using Farmland to Address Climate Change
https://www.wibc.com/news/local-news/using-farmland-address-climate-change

The ag research group Indigo has launched what it calls the Terraton Initiative, a decadelong research project with a goal of sucking a trillion tons of carbon out of the atmosphere and into the soil. Indigo's Chris Malone explains harnessing photosynthesis could simultaneously address greenhouse gases and make soil more productive.

[sidd]

Re: Indigo

Called em up a while ago. They seem more interested in buying and selling my grain than soil carbon capture. The person(s) i spoke to promised to return my calls with more information about soil carbon capture, but so far, deafening silence.

They did claim in the press material that they were working with the Rodale institute. I know some people there, will have to drop by next time i'm by Kutztown.

sidd

[Tom_Mazanec]

Cutting climate pollution isn't enough — we also need carbon removal
https://thehill.com/opinion/energy-environment/462609-cutting-climate-pollution-isnt-enough-we-also-need-carbon-removal

Achieving a 100 percent clean economy will require a swift transition to renewables and other zero-carbon energy sources. But we also need to face the reality that meeting the Paris target will require taking carbon out of the atmosphere at massive scale. In part, that’s because eliminating emissions will be very challenging for some sectors, especially the transportation industry and agriculture. Removing carbon from the atmosphere would also bring concentrations down, helping to stabilize the climate at safer levels. So, the push for clean energy must be supplemented by a suite of technologies known as carbon dioxide removal (CDR).

It is not a question of what we’d prefer. It’s a question of insurmountable math.

[Ken Feldman]

Here's a recent study on Negative Emissions Technologies (NET) needed for the 1.5C and 2C goals.

https://link.springer.com/article/10.1007%2Fs10584-019-02516-4

Negative emissions and international climate goals—learning from and about mitigation scenarios

Abstract
For aiming to keep global warming well-below 2 °C and pursue efforts to limit it to 1.5 °C, as set out in the Paris Agreement, a full-fledged assessment of negative emission technologies (NETs) that remove carbon dioxide from the atmosphere is crucial to inform science-based policy making. With the Paris Agreement in mind, we re-analyse available scenario evidence to understand the roles of NETs in 1.5 °C and 2 °C scenarios and, for the first time, link this to a systematic review of findings in the underlying literature. In line with previous research, we find that keeping warming below 1.5 °C requires a rapid large-scale deployment of NETs, while for 2 °C, we can still limit NET deployment substantially by ratcheting up near-term mitigation ambition. Most recent evidence stresses the importance of future socio-economic conditions in determining the flexibility of NET deployment and suggests opportunities for hedging technology risks by adopting portfolios of NETs. Importantly, our thematic review highlights that there is a much richer set of findings on NETs than commonly reflected upon both in scientific assessments and available reviews. In particular, beyond the common findings on NETs underpinned by dozens of studies around early scale-up, the changing shape of net emission pathways or greater flexibility in the timing of climate policies, there is a suite of “niche and emerging findings”, e.g. around innovation needs and rapid technological change, termination of NETs at the end of the twenty-first century or the impacts of climate change on the effectiveness of NETs that have not been widely appreciated. Future research needs to explore the role of climate damages on NET uptake, better understand the geophysical constraints of NET deployment (e.g. water, geological storage, climate feedbacks), and provide a more systematic assessment of NET portfolios in the context of sustainable development goals.

The Fifth Assessment Report (AR5) by IPCC Working Group 3 (WG3) provided a good overview of the role of NETs for stringent climate stabilization targets. It highlighted that many 2 °C scenarios entail large-scale deployment of NETs after 2050 to compensate for residual CO2 emissions from sectors that are difficult to decarbonize, such as industry and aviation. It warned that these scenarios are mostly associated with a temporary overshoot of the climate goal and that delays in climate action and limitations in the availability of NETs can render the 2 °C goal infeasible. It also emphasized the challenges (e.g. societal concerns), risks (e.g. technological availability, biodiversity, water, food prices, inter-generational impacts) and uncertainties (e.g. geological storage, large bioenergy production) surrounding these technologies (see also Electronic Supplementary Material (ESM) for a complete review of NET statements in AR5).

Yet, the analysis of NETs in WG3 AR5 remained inaccessible because findings were scattered in various sections and sub-sections of the report (i.e. in Chaps. 2, 6, 7, 11, 13).

The recent IPCC Special Report on Global Warming of 1.5 °C (SR1.5) (IPCC 2018) filled this gap by drawing upon a set of recent reviews (Minx et al. 2018; Fuss et al. 2018; Nemet et al., 2018) that used formal methods of evidence synthesis. It further added a comprehensive analysis on the role of NETs in 1.5 °C scenarios based on newly emerging evidence. The report highlighted that all 1.5 °C scenarios with limited or no overshoot require NETs on the order of 100–1000 GtCO2 over the twenty-first century but that significant near-term emissions reductions (e.g. low energy demand, low material consumption, low GHG-intensive food consumption) can limit NET deployment to a few hundred GtCO2 without reliance on Bioenergy with Carbon Capture and Storage (BECCS). It also called attention to the lack of published pathways featuring NETs other than afforestation and reforestation (AR) and BECCS (see also Electronic Supplementary Material (ESM) for a complete review of NET statements in Fuss et al. 2018, IPCC 2018 and Rogelj et al. 2018b).

[Ken Feldman]

Improved agricultural techniques can help restore soil productivity and sequester great amounts of carbon.  Here's an overview of carbon sequestration in soil.

https://wedocs.unep.org/bitstream/handle/20.500.11822/28453/Foresight013.pdf?sequence=1&isAllowed=y

The potential of carbon sequestration in the soil

Abstract

Soil’s contribution to climate change, through the oxidation of soil carbon, is important. However, soils – and thus agriculture - can play a major role in mitigating climate change. Through multiple agricultural practices, we could help store vast amounts of atmospheric carbon in the soil, while at the same time regenerating soil fertility, plant health and whole ecosystems. This is a no regret option that offers multiple benefits and deserves high-level visibility.

Estimates for carbon sequestration through improved practices vary considerably (Figure 3) as the understanding of the interactions and especially the knowledge of the behavior of soils is still limited. Various studies indicate theoretical potentials of 0.8 to 8 GtC per year 35,40,44,51,53–57, partially including af-/ re-forestation practices, and reaching up to 10 GtC/ yr of additional carbon on agricultural land 41,55, while practically achievable carbon removal amounts are rather located in the lower range of 1.5 to 2.5 GtC/yr 30,53,58. With global carbon emissions in 2016 from fossil fuels and industry of 9.9 GtC plus 1.3 GtC due to land-use changes (such as deforestation)v 38, the potential for carbon sequestration through regenerative agricultural practices looks rather promising, although the implementation of such practices comes with different social, economic and expertise-related and other caveats. It requires funding and collaboration amongst scientists, policymakers, practitioners and multiple other stakeholders. Soil carbon sequestration has a large but not infinite sink capacity, and, importantly, is reversible through bad management. Global efforts to gradually change land use practices are difficult to implement, reducing thus the theoretical mitigation potential

[Sigmetnow]

Mark Z. Jacobson on Twitter: "People who support Carbon Capture+Direct Air Capture are condemning millions worldwide to die from pollution, which those techs increase or hold constant. They are also increasing CO2 compared w/spending same money on clean, renewables to replace fossils”
https://mobile.twitter.com/mzjacobson/status/1192913918374621185

The paper:

...Moreover, the CCU and SDACCU plants both increase air pollution and total social costs relative to no capture. Using wind to power the equipment reduces CO2e relative to using natural gas but still allows air pollution emissions to continue and increases the total social cost relative to no carbon capture. Conversely, using wind to displace coal without capturing carbon reduces CO2e, air pollution, and total social cost substantially. ...

https://web.stanford.edu/group/efmh/jacobson/Articles/Others/19-CCS-DAC.pdf

[Ken Feldman]

Enhanced rock weathering is another method to remove carbon dioxide from the air while improving the quality of agricultural soils.

https://www.nature.com/articles/s41586-020-2448-9

Beerling, D.J., Kantzas, E.P., Lomas, M.R. et al. Potential for large-scale CO2 removal via enhanced rock weathering with croplands. Nature 583, 242–248 (2020).

Abstract

Enhanced silicate rock weathering (ERW), deployable with croplands, has potential use for atmospheric carbon dioxide (CO2) removal (CDR), which is now necessary to mitigate anthropogenic climate change1. ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification2,3,4. Here we use an integrated performance modelling approach to make an initial techno-economic assessment for 2050, quantifying how CDR potential and costs vary among nations in relation to business-as-usual energy policies and policies consistent with limiting future warming to 2 degrees Celsius5. China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2 gigatonnes of carbon dioxide (CO2) per year with extraction costs of approximately US$80–180 per tonne of CO2. These goals and costs are robust, regardless of future energy policies. Deployment within existing croplands offers opportunities to align agriculture and climate policy. However, success will depend upon overcoming political and social inertia to develop regulatory and incentive frameworks. We discuss the challenges and opportunities of ERW deployment, including the potential for excess industrial silicate materials (basalt mine overburden, concrete, and iron and steel slag) to obviate the need for new mining, as well as uncertainties in soil weathering rates and land–ocean transfer of weathered products.