11.10.2021

# New Publications

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Saeed Arabi, S. M.; et al. (2021): Capturing atmospheric carbon dioxide by depleting inorganic carbon in municipal wastewater

Arabi, S. SaeedM.; Alicata, Jackson; Hanigan, David; Hiibel, Sage R. (2021): Capturing atmospheric carbon dioxide by depleting inorganic carbon in municipal wastewater. In International Journal of Greenhouse Gas Control 111, p. 103472. DOI: 10.1016/j.ijggc.2021.103472.

"CO2 removal from the atmosphere will likely be necessary to limit global warming to 2 ℃. Existing wastewater infrastructure in the U.S. conveys a total of 588 Mt of inorganic carbon to wastewater treatment plants, which are designed to remove organic carbon, but do not remove the inorganic fraction. We believe that embedded energy used for wastewater conveyance may be leveraged to remove inorganic carbon and produce wastewater treatment plants that are net carbon negative. To demonstrate this, we optimized a bench-scale wastewater carbon-capture system composed of a gas permeable membrane and a pressurized feed. We investigated the effects of multiple physicochemical parameters on inorganic carbon removal. The best performance resulted in removal of 15% inorganic carbon from the feed stream. Deploying similar full-scale systems across U.S. wastewater infrastructure without addition of acid would remove up to 12.9 Mt-C/yr. Hydrochrloric acid addition to one pH unit below the bicarbonate pKa would increase removal to 30.5 Mt-C/yr, but this is partially offset by CO2 emissions from hydrochloric acid production, resulting in a net removal of 22.6 Mt-C/yr. Further research should focus on increasing removal efficiency, which, at 100% removal, would offset 11.2% of total U.S. CO2 gas emissions."

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10.10.2021

# New Publications

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van Schagen, T. N.; et al. (2021): Development of a novel, through-flow microwave-based regenerator for sorbent-based direct air capture

van Schagen, T. N.; van der Wal, P. J.; Brilman, D.W.F. (2021): Development of a novel, through-flow microwave-based regenerator for sorbent-based direct air capture. In Chemical Engineering Journal Advances 42 (8), p. 100187. DOI: 10.1016/j.ceja.2021.100187.

"In this work an all-electric regenerator is developed for the desorption of CO2 from air-capture sorbents using microwaves. An electromagnetic model was made for a continuous flow radial desorber and its dimensions were optimised for maximal microwave utilisation. Based on the optimal dimensions an actual prototype, capable of desorbing CO2 from a commercial supported amine sorbent in fixed- or moving-bed configuration was built to demonstrate the concept and to study performance characteristics. TSA experiments using nitrogen as purge gas to produce enriched air (1 to 2 vol. % CO2) were done. Productivities of up to 1.5 kg CO2/kgsorb./d were demonstrated, with a total energy duty of 25 MJ/kgCO2. Compared to traditional TVSA desorption, the energy duty is similar while the productivity is significantly higher. The process can be further improved by creating an even more homogeneous electric field (preventing hot spots in the regenerator) and by enabling desorption under vacuum conditions to produce pure CO2. Overall, microwave desorption is demonstrated as an effective way to circumvent heat transfer limitations present during more traditional thermal desorption processes using polymeric sorbents."

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10.10.2021

# New Publications

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Kieft, Brandon; et al. (2021): Phytoplankton exudates and lysates support distinct microbial consortia with specialized metabolic and ecophysiological traits

Kieft, Brandon; Li, Zhou; Bryson, Samuel; Hettich, Robert L.; Pan, Chongle; Mayali, Xavier; Mueller, Ryan S. (2021): Phytoplankton exudates and lysates support distinct microbial consortia with specialized metabolic and ecophysiological traits. In Proceedings of the National Academy of Sciences of the United States of America 118 (41). DOI: 10.1073/pnas.2101178118.

"Blooms of marine phytoplankton fix complex pools of dissolved organic matter (DOM) that are thought to be partitioned among hundreds of heterotrophic microbes at the base of the food web. While the relationship between microbial consumers and phytoplankton DOM is a key component of marine carbon cycling, microbial loop metabolism is largely understood from model organisms and substrates. Here, we took an untargeted approach to measure and analyze partitioning of four distinct phytoplankton-derived DOM pools among heterotrophic populations in a natural microbial community using a combination of ecogenomics, stable isotope probing (SIP), and proteomics. Each 13C-labeled exudate or lysate from a diatom or a picocyanobacterium was preferentially assimilated by different heterotrophic taxa with specialized metabolic and physiological adaptations."

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10.10.2021

# New Publications

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Haque, Fatima; et al. (2021): Urban Farming with Enhanced Rock Weathering As a Prospective Climate Stabilization Wedge

Haque, Fatima; Santos, Rafael M.; Chiang, Yi Wai (2021): Urban Farming with Enhanced Rock Weathering As a Prospective Climate Stabilization Wedge. In Environmental science & technology. DOI: 10.1021/acs.est.1c04111.

"With no single carbon capture and sequestration solution able to limit the global temperature rise to 1.5–2.0 °C by 2100, additional climate stabilization measures are needed to complement current mitigation approaches. Urban farming presents an easy-to-adopt pathway toward carbon neutrality, unlocking extensive urban surface areas that can be leveraged to grow food while sequestering CO2. Urban farming involves extensive surface areas, such as roofs, balconies, and vertical spaces, allowing for soil presence and atmospheric carbon sequestration through air-to-soil contact. In this viewpoint we also advocate the incorporation of enhanced rock weathering (ERW) into urban farming, providing a further opportunity for this recognized negative emissions technology that is gaining momentum worldwide to gain greater utilization."

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08.10.2021

# New Publications

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Joppa, Lucas; et al. (2021): Microsoft's million-tonne CO2-removal purchase - lessons for net zero

Joppa, Lucas; Luers, Amy; Willmott, Elizabeth; Friedmann, S. Julio; Hamburg, Steven P.; Broze, Rafael (2021): Microsoft's million-tonne CO2-removal purchase - lessons for net zero. In Nature 597 (7878), pp. 629–632. DOI: 10.1038/d41586-021-02606-3.

"Strengthen markets, measures and definitions for removing carbon dioxide from the atmosphere to fight climate change. In January this year, Microsoft made a major announcement: it had paid for the removal of 1.3 million tonnes of carbon dioxide from the atmosphere. Among its purchases were projects to expand forests in Peru, Nicaragua and the United States, as well as initiatives to regenerate soil across US farms. [...] Here we summarize the lessons learnt from Microsoft’s carbon-removal efforts, along with those from another early corporate procurement — the $9-million purchases of carbon removal in 2020 and 2021 by the US–Irish financial-infrastructure company Stripe. Although these are just two companies’ efforts, they are the first significant open solicitations focused exclusively on carbon removal. We write as a team composed of Microsoft staff working on the company’s carbon-negative programme and research scientists who analyse carbon reduction and removal strategies."

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08.10.2021

# New Publications

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Berndes, Göran; Cowie, Annette (2021): Land sector impacts of early climate action

Berndes, Göran; Cowie, Annette (2021): Land sector impacts of early climate action. In Nat Sustain 3, p. 515. DOI: 10.1038/s41893-021-00777-5.

"Integrated assessment models are widely used to assess climate change mitigation strategies. Comparing scenarios from several integrated assessment models, a study now highlights the benefits and trade-offs of near-term mitigation to reduce mitigation challenges in the longer term."

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08.10.2021

# New Publications

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Hasegawa, Tomoko; et al. (2021): Land-based implications of early climate actions without global net-negative emissions

Hasegawa, Tomoko; Fujimori, Shinichiro; Frank, Stefan; Humpenöder, Florian; Bertram, Christoph; Després, Jacques et al. (2021): Land-based implications of early climate actions without global net-negative emissions. In Nat Sustain 573, p. 357. DOI: 10.1038/s41893-021-00772-w.

"Delaying climate mitigation action and allowing a temporary overshoot of temperature targets require large-scale carbon dioxide removal (CDR) in the second half of this century that may induce adverse side effects on land, food and ecosystems. Meanwhile, meeting climate goals without global net-negative emissions inevitably needs early and rapid emission reduction measures, which also brings challenges in the near term. Here we identify the implications for land-use and food systems of scenarios that do not depend on land-based CDR technologies. We find that early climate action has multiple benefits and trade-offs, and avoids the need for drastic (mitigation-induced) shifts in land use in the long term. Further long-term benefits are lower food prices, reduced risk of hunger and lower demand for irrigation water. Simultaneously, however, near-term mitigation pressures in the agriculture, forest and land-use sector and the required land area for energy crops increase, resulting in additional risk of food insecurity."

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07.10.2021

# New Publications

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Du, Yang; et al. (2021): Zero- and negative-emissions fossil-fired power plants using CO2 capture by conventional aqueous amines

Du, Yang; Gao, Tianyu; Rochelle, Gary T.; Bhown, Abhoyjit S. (2021): Zero- and negative-emissions fossil-fired power plants using CO2 capture by conventional aqueous amines. In International Journal of Greenhouse Gas Control 111, p. 103473. DOI: 10.1016/j.ijggc.2021.103473.

"This work investigated the technical and economic feasibility of achieving zero and negative CO2 emissions in both pulverized coal (PC) and natural gas combined cycle (NGCC) power plants, using conventional amine scrubbing with 30 wt% aqueous monoethanolamine. In this work, we refer to “zero emissions” when the amount of CO2 in the exhaust flue gas is equal to that in the intake combustion air, and “negative emissions” when the amount of CO2 in the exhaust flue gas is less that in the intake combustion air. Increasing CO2 capture from 90% to that at zero-emissions for fossil-fired power plants can reduce global CO2 emissions by up to ∼1 Gt/y for the current global power generation mix. Even higher CO2 capture leads to negative emissions of the power plant with part of the CO2 from the intake air removed along with the fossil-fuel derived CO2. With an absorber configuration including a simple solvent intercooler, both PC and NGCC power plants can achieve zero-emissions with a ∼5% and ∼13% increase in CO2 avoidance costs, compared with the costs at 90% CO2 capture. The larger cost penalty for NGCC was mainly due to a temperature bulge at the absorber top. Replacing the simple solvent intercooler with a pump-around intercooler was able to reduce this cost penalty to ∼8%. Further decarbonization of flue gases from zero-emissions to direct air capture (DAC)-level of negative emissions (∼100 ppmv of CO2 in exhaust gases) has incremental costs of over $1000/t CO2 avoided for both PC and NGCC."

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07.10.2021

# New Publications

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Grossmann, Quirin; et al. (2021): Molecular to Process Scale: A Review of Holistic Direct Air Capture Contactor Design

Grossmann, Quirin; Stampi-Bombelli, Valentina; Mazzotti, Marco (2021): Molecular to Process Scale: A Review of Holistic Direct Air Capture Contactor Design. In SINTEF Proceedings (7). Available online at https://sintef.brage.unit.no/sintef-xmlui/bitstream/handle/11250/2786929/Molecular%20to%20Process%20Scale%20A%20Review%20of%20Holistic%20Direct%20Air%20Capture%20Contactor%20Design.pdf?sequence=1&isAllowed=y.

"Air-sorbent contactors are an essential part of direct air capture processes. Their design can have a great influence on the process energy demand and efficiency. Three aspects of this design have been identified and differentiated by length scale. On a molecular scale, the adsorption sites are defined by the chemisorbent-containing molecules, generally amines. The support of these amines defines the second length scale and plays an important role in mass and heat transfer. These two length scales have been studied in detail in academic literature and a short overview is given. The third length scale is the process scale, or contactor module scale. Together with the first two length scales, it is necessary to characterize the third to perform adequate process optimization. Research on this third length scale is scarce in academic literature, though it has been researched in industry. The direction of research tends towards structured sorbents due to their ability to process large volumes of air and academic research in this area should be expanded."

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06.10.2021

# New Publications

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Baiman, Ron (2021): In Support of a Renewable Energy and Materials Economy: A Global Green New Deal That Includes Arctic Sea Ice Triage and Carbon Cycle Restoration

Baiman, Ron (2021): In Support of a Renewable Energy and Materials Economy: A Global Green New Deal That Includes Arctic Sea Ice Triage and Carbon Cycle Restoration. In Review of Radical Political Economics, 048661342110323. DOI: 10.1177/04866134211032396.

"A Global Green New Deal (GGND)—that includes Arctic sea ice climate triage and carbon cycle climate restoration, and that, following Eisenberger (2020), would move us toward a renewable energy and materials economy (REME)—is necessary to turn our current civilization and species-threatening climate crises into an opportunity to stabilize our planet’s climate and advance to a new, more equitable and prosperous stage of human development. Imminent, potentially catastrophic, global climate impacts of Arctic sea ice loss, the first global climate “tipping point,” are reviewed, and practical and efficient potential climate triage methods for avoiding this are summarized. Longer-term carbon dioxide removal (CDR) and carbon capture, sequestration, and use (CCSU) methods, that would move us toward long-term carbon cycle climate restoration, are presented. A general reframing of climate policy and specific GGND policy proposals—that include Arctic sea ice climate triage and carbon cycle climate restoration that would rapidly move us toward a REME and avoid increasingly catastrophic climate impacts—are proposed."

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