Cutting through the noise on negative emissions

Recent advances in direct air capture by adsorption

“…Considering that the results of LCA highly depend on the original data adopted, the following metrics should be carefully evaluated for adsorption-based DAC: (1) the raw materials used to fabricate adsorbent materials, (2) the types of energy used to power the operation, (3) whether renewable energy was adopted as the power source, and (4) the raw material and equipment installation for such renewable energy. After comprehensively comparing a set of NETs using LCA, Terlouw et al 50 pointed out that avoided emissions due to the substitution of certain processes can be easily misinterpreted as negative emissions.…”

“…Emissions from these sources lead to the total CO 2 emissions approaching 40 Gt year À1 . 1 Although facing several limitations, integrated assessment models (IAMs), 2 the most effective tool for predicting the CO 2 emission change in response to temperature rise target, suggested that the CO 2 capture rate should reach 8-50 Gt year À1 by 2100 to ensure the global average temperature rise within 2 1C. 3 Negative emission technologies (NETs) with a cumulative CO 2 capture of 450-1000 Gt between 2010 and 2100 are required to achieve the more stringent 1.5 1C temperature rise target.…”

Is carbon removal delaying emission reductions?

“…Some see this debate as unduly selective because conventional mitigation methods too might fail—implying that an exclusive focus on emission reductions could deter the development of CDR methods that might ultimately be needed (Fridahl, 2019; Nordhaus, 2018). Others make a clear distinction between MH/MD dynamics in integrated assessment models (IAMs), and “actual” MH/MD, suggesting that indications of the former do not necessarily reflect real‐world risks of MH/MD (Bellamy et al, 2021; Minx et al, 2018; Uden et al, 2021).…”

“…Close attention to such structural processes provides a retort to common critiques of the MH/MD concept, including the idea that it has a weak empirical basis (Colvin et al, 2020) or that it is exclusively a construct of IAMs (Uden et al, 2021). A paper by Jebari et al (2021) presents perhaps the most elaborate version of this critique, arguing that MH/MD concerns might be a self‐fulfilling prophecy and themselves constitute a moral hazard, because they make it seem “as though the use of carbon capture or solar geoengineering technologies can serve as potential substitutes for mitigation efforts” (Jebari et al, 2021, p. 3).…”

A review of II–VI semiconductor nanoclusters for photocatalytic CO2 conversion: synthesis, characterization, and mechanisms

“…[1][2][3] Converting CO 2 into high-value-added fuels, chemicals, and other target compounds is not only a potential negative carbon emission strategy, but also an effective approach for the resourceful use of CO 2 , which is consistent with the concept of green and sustainable development. [4][5][6][7][8] In recent years, photocatalytic CO 2 conversion has aroused great interest, exhibiting great theoretical value and application prospects. [9][10][11][12] Generally, an ideal material for photocatalytic CO 2 conversion should be stable and able to respond to a wide range of solar spectra for the generation of photoinduced electron-hole pairs with high efficiency.…”