1,426,082 research outputs found
COVID-19 causes record decline in global CO2 emissions
The considerable cessation of human activities during the COVID-19 pandemic
has affected global energy use and CO2 emissions. Here we show the
unprecedented decrease in global fossil CO2 emissions from January to April
2020 was of 7.8% (938 Mt CO2 with a +6.8% of 2-{\sigma} uncertainty) when
compared with the period last year. In addition other emerging estimates of
COVID impacts based on monthly energy supply or estimated parameters, this
study contributes to another step that constructed the near-real-time daily CO2
emission inventories based on activity from power generation (for 29
countries), industry (for 73 countries), road transportation (for 406 cities),
aviation and maritime transportation and commercial and residential sectors
emissions (for 206 countries). The estimates distinguished the decline of CO2
due to COVID-19 from the daily, weekly and seasonal variations as well as the
holiday events. The COVID-related decreases in CO2 emissions in road
transportation (340.4 Mt CO2, -15.5%), power (292.5 Mt CO2, -6.4% compared to
2019), industry (136.2 Mt CO2, -4.4%), aviation (92.8 Mt CO2, -28.9%),
residential (43.4 Mt CO2, -2.7%), and international shipping (35.9Mt CO2,
-15%). Regionally, decreases in China were the largest and earliest (234.5 Mt
CO2,-6.9%), followed by Europe (EU-27 & UK) (138.3 Mt CO2, -12.0%) and the U.S.
(162.4 Mt CO2, -9.5%). The declines of CO2 are consistent with regional
nitrogen oxides concentrations observed by satellites and ground-based
networks, but the calculated signal of emissions decreases (about 1Gt CO2) will
have little impacts (less than 0.13ppm by April 30, 2020) on the overserved
global CO2 concertation. However, with observed fast CO2 recovery in China and
partial re-opening globally, our findings suggest the longer-term effects on
CO2 emissions are unknown and should be carefully monitored using multiple
measures
Infrared spectra of van de Waals complexes of importance in planetary atmospheres
It has been suggested that (CO2)2 and Ar-CO2 are important constituents of the planetary atmospheres of Venus and Mars. Recent results on the laboratory spectroscopy of CO2 containing van der Waals complexes which may be of use in the modeling of the spectra of planetary atmospheres are presented. Sub-Doppler infrared spectra were obtained for (CO2)2, (CO2)3, and rare-gas-CO2 complexes in the vicinity of the CO2 Fermi diad at 2.7 micrometers using a color-center-laser optothermal spectrometer. From the spectroscopic constants the geometries of the complexes have been determined and van der Waals vibrational frequencies have been estimated. The equilibrium configurations are C2h, C3h, and C2v, for (CO2)2, (CO2)3, and the rare-gas-CO2 complexes, respectively. Most of the homogeneous linewidths for the revibrational transitions range from 0.5 to 22 MHz, indicating that predissociation is as much as four orders of magnitude faster than radiative processes for vibrational relaxation in these complexes
MOBILITY REDUCTION OF CO2 USING CO2 SOLUBLE SURFACTANTS
Addition of slightly CO2-soluble, brine-soluble, surfactants to high pressure CO2 for EOR may facilitate in-situ generation of CO2-in-brine foams for mobility control. These non-ionic surfactants have been demonstrated to dissolve in CO2 to concentrations of 0.1wt% at reservoir conditions and stabilize CO2-in-brine foams in a high pressure windowed cell. One such surfactant is Huntsman SURFONIC® N, a branched nonylphenol ethoxylates with averages of 12 (N-120) or 15(N-150) ethylene oxide repeat units in the hydrophile. SURFONIC® N-120 was selected for mobility reduction studies involving flow of CO2 into brine-saturated porous media.
Transient mobility measurements were conducted using a water-wet Berea core (104mD), water-wet Bentheimer sandstone core (~1500mD), and several SACROC carbonate cores (3.6 and 8.9mD). The CO2 was injected into brine-saturated cores at superficial velocity of 10 ft/day, and surfactant was either not used (control), dissolved only in brine at 0.07wt%, dissolved only in CO2 at ~0.07wt%, or dissolved in brine and CO2 at 0.07wt%. In general, in-situ foam generation in relatively high permeability sandstone was evidenced during the first few pore volumes of CO2 injected by pressure drops that were 2-3 times greater than control tests regardless of what phase CO2 was in. Mobility reduction was more modest (20–50% increases in pressure drop) in lower permeability SACROC cores (3.6 and 8.9mD) when surfactant was dissolved in CO2. With surfactant dissolved in brine, pressure drops increased by a factor of 2–3 when CO2 was injected into an 8.9mD core.
High pressure CT imaging of in-situ foam generation was conducted by injecting high pressure CO2 into 5wt% KI-brine-saturated Berea sandstone (3-8mD). Tests with no surfactant (control), or with surfactant dissolved either brine or CO2 at ~0.07wt%. At lower superficial velocities (0.47ft/day), in-siti foam generation was obvious only when surfactant was dissolved in brine. Higher flow rates (4.7ft/day) preferential flow of CO2 through high permeability layers and viscous fingering within layers that occurred during control tests was suppressed by addition of surfactant to either CO2 or brine. The most distinct CO2 foam front occurred with surfactant dissolved in brine
Sequestering atmospheric CO<sub>2</sub> inorganically:a solution for Malaysia's CO<sub>2</sub> emission
Malaysia is anticipating an increase of 68.86% in CO2 emission in 2020, compared with the 2000 baseline, reaching 285.73 million tonnes. A major contributor to Malaysia's CO2 emissions is coal-fired electricity power plants, responsible for 43.4% of the overall emissions. Malaysia's forest soil offers organic sequestration of 15 tonnes of CO2 ha(-1) year(-1). Unlike organic CO2 sequestration in soil, inorganic sequestration of CO2 through mineral carbonation, once formed, is considered as a permanent sink. Inorganic CO2 sequestration in Malaysia has not been extensively studied, and the country's potential for using the technique for atmospheric CO2 removal is undefined. In addition, Malaysia produces a significant amount of solid waste annually and, of that, demolition concrete waste, basalt quarry fine, and fly and bottom ashes are calcium-rich materials suitable for inorganic CO2 sequestration. This project introduces a potential solution for sequestering atmospheric CO2 inorganically for Malaysia. If lands associated to future developments in Malaysia are designed for inorganic CO2 sequestration using demolition concrete waste, basalt quarry fine, and fly and bottom ashes, 597,465 tonnes of CO2 can be captured annually adding a potential annual economic benefit of (sic)4,700,000.</p
Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream
Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon (14C) and stable carbon (δ13C) isotopic composition of dissolved CO2 for the first time in a peatland stream throughout a complete year (May 2010 – June 2011). The in-stream sampling system collected time-integrated samples of CO2 continuously over approximately one month periods. The rate of CO2 trapping was proportional to independently measured streamwater CO2 concentrations, demonstrating that passive samplers can be used to estimate the time-averaged dissolved CO2 concentration of streamwater. While there was little variation and no clear trend in δ13CO2 values (suggesting a consistent CO2 source), we found a clear temporal pattern in the 14C concentration of dissolved CO2. The 14C age of CO2 varied from 707±35 to 1210±39 years BP, with the youngest CO2 in the autumn and oldest in spring/early summer. Mean stream discharge and 14C content of dissolved CO2 were positively correlated. We suggest that the observed pattern in the 14C content of dissolved CO2 reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow
Global Roadmap for Implementing CO2 Utilization
CO2U’s potential: Profitable markets and mitigated CO2 emissions
At full scale, 5 CO2U products (see below) could create a market over US 0.8-1.1 Trillion.
Roadmap to 2030: Market size and mitigation impact
Market size and CO2 reduction potential can be significantly impacted by taking action now.
Below are examples from five markets. For example, the market for CO2-based fuels can be
quadrupled by 2025 (from 200b), increasing the CO2 reduction by 15 fold (from 0.03b tons to 0.5b tons). Similarly, decisive and timely action can have a major impact on both the market size and potential to mitigate CO2 emissions for other CO2-based products.We are deeply grateful to the Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO), Japan, for launching and supporting the ICEF Roadmap Project of which this is a part. NEDO commissioned CO2
Sciences to conduct this roadmap on CO2 Utilization. We acknowledge, with great appreciation, the support from The Lemelson Foundation and the RK Mellon Family Foundation for this work.https://deepblue.lib.umich.edu/bitstream/2027.42/150624/1/CO2U_Roadmap_FINAL_2016_12_07(GCI).pdf-1Description of CO2U_Roadmap_FINAL_2016_12_07(GCI).pdf : Global Roadmap for Implementing CO2 Utilization; a report by the Global CO2 Initiative (2016
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Experimental study on transcritical Rankine cycle (TRC) using CO2/R134a mixtures with various composition ratios for waste heat recovery from diesel engines
A carbon dioxide (CO2) based mixture was investigated as a promising solution to improve system performance and expand the condensation temperature range of a CO2 transcritical Rankine cycle (C-TRC). An experimental study of TRC using CO2/R134a mixtures was performed to recover waste heat of engine coolant and exhaust gas from a heavy-duty diesel engine. The main purpose of this study was to investigate experimentally the effect of the composition ratio of CO2/R134a mixtures on system performance. Four CO2/R134a mixtures with mass composition ratios of 0.85/0.15, 0.7/0.3, 0.6/0.4 and 0.4/0.6 were selected. The high temperature working fluid was expanded through an expansion valve and then no power was produced. Thus, current research focused on the analysis of measured operating parameters and heat exchanger performance. Heat transfer coefficients of various heat exchangers using supercritical CO2/R134a mixtures were provided and discussed. These data may provide useful reference for cycle optimization and heat exchanger design in application of CO2 mixtures. Finally, the potential of power output was estimated numerically. Assuming an expander efficiency of 0.7, the maximum estimations of net power output using CO2/R134a (0.85/0.15), CO2/R134a (0.7/0.3), CO2/R134a (0.6/0.4) and CO2/R134a (0.4/0.6) are 5.07 kW, 5.45 kW, 5.30 kW, and 4.41 kW, respectively. Along with the increase of R134a composition, the estimation of net power output, thermal efficiency and exergy efficiency increased at first and then decreased. CO2/R134a (0.7/0.3) achieved the maximum net power output at a high expansion inlet pressure, while CO2/R134a (0.6/0.4) behaves better at low pressure
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