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国际可再生能源署预计绿氢成本有望在2050年降至0.65美元 快报文章
气候变化快报,2022年第12期
作者:  秦冰雪
Microsoft Word(15Kb)  |  收藏  |  浏览/下载:698/0  |  提交时间:2022/06/20
Net Zero Energy  Green Hydrogen  Cost and Potential  
Potential for large-scale CO2 removal via enhanced rock weathering with croplands 期刊论文
NATURE, 2020, 583 (7815) : 242-+
作者:  David J. Beerling;  Euripides P. Kantzas;  Mark R. Lomas;  Peter Wade;  Rafael M. Eufrasio;  Phil Renforth;  Binoy Sarkar;  M. Grace Andrews;  Rachael H. James;  Christopher R. Pearce;  Jean-Francois Mercure;  Hector Pollitt;  Philip B. Holden;  Neil R. Edwards;  Madhu Khanna;  Lenny Koh;  Shaun Quegan;  Nick F. Pidgeon;  Ivan A. Janssens;  James Hansen;  Steven A. Banwart
收藏  |  浏览/下载:18/0  |  提交时间:2020/07/14

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 change(1). ERW also has possible co-benefits for improved food and soil security, and reduced ocean acidification(2-4). 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 Celsius(5). China, India, the USA and Brazil have great potential to help achieve average global CDR goals of 0.5 to 2gigatonnes 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.


  
Weakening of the Extratropical Storm Tracks in Solar Geoengineering Scenarios 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2020, 47 (11)
作者:  Gertler, Charles G.;  39;Gorman, Paul A.
收藏  |  浏览/下载:5/0  |  提交时间:2020/05/13
Storm Tracks  Geoengineering  Available Potential Energy  Climate Change  Extratropical Cyclones  
Iron-based binary ferromagnets for transverse thermoelectric conversion 期刊论文
NATURE, 2020, 581 (7806) : 53-+
作者:  Grun, Rainer;  Pike, Alistair;  McDermott, Frank;  Eggins, Stephen;  Mortimer, Graham;  Aubert, Maxime;  Kinsley, Lesley;  Joannes-Boyau, Renaud;  Rumsey, Michael;  Denys, Christiane;  Brink, James;  Clark, Tara;  Stringer, Chris
收藏  |  浏览/下载:31/0  |  提交时间:2020/07/03

Aluminium- and gallium-doped iron compounds show a large anomalous Nernst effect owing to a topological electronic structure, and their films are potentially suitable for designing low-cost, flexible microelectronic thermoelectric generators.


Thermoelectric generation using the anomalous Nernst effect (ANE) has great potential for application in energy harvesting technology because the transverse geometry of the Nernst effect should enable efficient, large-area and flexible coverage of a heat source. For such applications to be viable, substantial improvements will be necessary not only for their performance but also for the associated material costs, safety and stability. In terms of the electronic structure, the anomalous Nernst effect (ANE) originates from the Berry curvature of the conduction electrons near the Fermi energy(1,2). To design a large Berry curvature, several approaches have been considered using nodal points and lines in momentum space(3-10). Here we perform a high-throughput computational search and find that 25 percent doping of aluminium and gallium in alpha iron, a naturally abundant and low-cost element, dramatically enhances the ANE by a factor of more than ten, reaching about 4 and 6 microvolts per kelvin at room temperature, respectively, close to the highest value reported so far. The comparison between experiment and theory indicates that the Fermi energy tuning to the nodal web-a flat band structure made of interconnected nodal lines-is the key for the strong enhancement in the transverse thermoelectric coefficient, reaching a value of about 5 amperes per kelvin per metre with a logarithmic temperature dependence. We have also succeeded in fabricating thin films that exhibit a large ANE at zero field, which could be suitable for designing low-cost, flexible microelectronic thermoelectric generators(11-13).


  
Hydraulic Potential Energy Model for Hydropower Operation in Mixed Reservoir Systems 期刊论文
WATER RESOURCES RESEARCH, 2020, 56 (4)
作者:  Wan, Wenhua;  Wang, Hao;  Zhao, Jianshi
收藏  |  浏览/下载:7/0  |  提交时间:2020/07/02
Hydraulic potential energy  forecast-informed operation  energy transformation formula  relative marginal energy principle  two-stage hydraulic potential energy model  
Detection of metastable electronic states by Penning trap mass spectrometry 期刊论文
NATURE, 2020, 581 (7806) : 42-+
作者:  Rauch, Jennifer N.;  Luna, Gabriel;  Guzman, Elmer;  Audouard, Morgane;  Challis, Collin;  Sibih, Youssef E.;  Leshuk, Carolina;  Hernandez, Israel;  Wegmann, Susanne;  Hyman, Bradley T.;  Gradinaru, Viviana;  Kampmann, Martin;  Kosik, Kenneth S.
收藏  |  浏览/下载:9/0  |  提交时间:2020/07/03

State-of-the-art optical clocks(1) achieve precisions of 10(-18) or better using ensembles of atoms in optical lattices(2,3) or individual ions in radio-frequency traps(4,5). Promising candidates for use in atomic clocks are highly charged ions(6) (HCIs) and nuclear transitions(7), which are largely insensitive to external perturbations and reach wavelengths beyond the optical range(8) that are accessible to frequency combs(9). However, insufficiently accurate atomic structure calculations hinder the identification of suitable transitions in HCIs. Here we report the observation of a long-lived metastable electronic state in an HCI by measuring the mass difference between the ground and excited states in rhenium, providing a non-destructive, direct determination of an electronic excitation energy. The result is in agreement with advanced calculations. We use the high-precision Penning trap mass spectrometer PENTATRAP to measure the cyclotron frequency ratio of the ground state to the metastable state of the ion with a precision of 10(-11)-an improvement by a factor of ten compared with previous measurements(10,11). With a lifetime of about 130 days, the potential soft-X-ray frequency reference at 4.96 x 10(16) hertz (corresponding to a transition energy of 202 electronvolts) has a linewidth of only 5 x 10(-8) hertz and one of the highest electronic quality factors (10(24)) measured experimentally so far. The low uncertainty of our method will enable searches for further soft-X-ray clock transitions(8,12) in HCIs, which are required for precision studies of fundamental physics(6).


Penning trap mass spectrometry is used to measure the electronic transition energy from a long-lived metastable state to the ground state in highly charged rhenium ions with a precision of 10(-11).


  
In situ NMR metrology reveals reaction mechanisms in redox flow batteries 期刊论文
NATURE, 2020, 579 (7798) : 224-+
作者:  Ma, Jianfei;  You, Xin;  Sun, Shan;  Wang, Xiaoxiao;  Qin, Song;  Sui, Sen-Fang
收藏  |  浏览/下载:12/0  |  提交时间:2020/07/03

Large-scale energy storage is becoming increasingly critical to balancing renewable energy production and consumption(1). Organic redox flow batteries, made from inexpensive and sustainable redox-active materials, are promising storage technologies that are cheaper and less environmentally hazardous than vanadium-based batteries, but they have shorter lifetimes and lower energy density(2,3). Thus, fundamental insight at the molecular level is required to improve performance(4,5). Here we report two in situ nuclear magnetic resonance (NMR) methods of studying redox flow batteries, which are applied to two redox-active electrolytes: 2,6-dihydroxyanthraquinone (DHAQ) and 4,4 '  -((9,10-anthraquinone-2,6-diyl)dioxy) dibutyrate (DBEAQ). In the first method, we monitor the changes in the H-1 NMR shift of the liquid electrolyte as it flows out of the electrochemical cell. In the second method, we observe the changes that occur simultaneously in the positive and negative electrodes in the full electrochemical cell. Using the bulk magnetization changes (observed via the H-1 NMR shift of the water resonance) and the line broadening of the H-1 shifts of the quinone resonances as a function of the state of charge, we measure the potential differences of the two single-electron couples, identify and quantify the rate of electron transfer between the reduced and oxidized species, and determine the extent of electron delocalization of the unpaired spins over the radical anions. These NMR techniques enable electrolyte decomposition and battery self-discharge to be explored in real time, and show that DHAQ is decomposed electrochemically via a reaction that can be minimized by limiting the voltage used on charging. We foresee applications of these NMR methods in understanding a wide range of redox processes in flow and other electrochemical systems.


  
Limits on gas impermeability of graphene 期刊论文
NATURE, 2020, 579 (7798) : 229-+
作者:  Pagano, Justin K.;  Xie, Jing;  Erickson, Karla A.;  Cope, Stephen K.;  Scott, Brian L.;  Wu, Ruilian;  Waterman, Rory;  Morris, David E.;  Yang, Ping;  Gagliardi, Laura;  Kiplinger, Jaqueline L.
收藏  |  浏览/下载:28/0  |  提交时间:2020/07/03

Despite being only one-atom thick, defect-free graphene is considered to be completely impermeable to all gases and liquids(1-10). This conclusion is based on theory(3-8) and supported by experiments(1,9,10) that could not detect gas permeation through micrometre-size membranes within a detection limit of 10(5) to 10(6) atoms per second. Here, using small monocrystalline containers tightly sealed with graphene, we show that defect-free graphene is impermeable with an accuracy of eight to nine orders of magnitude higher than in the previous experiments. We are capable of discerning (but did not observe) permeation of just a few helium atoms per hour, and this detection limit is also valid for all other gases tested (neon, nitrogen, oxygen, argon, krypton and xenon), except for hydrogen. Hydrogen shows noticeable permeation, even though its molecule is larger than helium and should experience a higher energy barrier. This puzzling observation is attributed to a two-stage process that involves dissociation of molecular hydrogen at catalytically active graphene ripples, followed by adsorbed atoms flipping to the other side of the graphene sheet with a relatively low activation energy of about 1.0 electronvolt, a value close to that previously reported for proton transport(11,12). Our work provides a key reference for the impermeability of two-dimensional materials and is important from a fundamental perspective and for their potential applications.


  
Power generation from ambient humidity using protein nanowires 期刊论文
NATURE, 2020, 578 (7796) : 550-+
作者:  Luong, Duy X.;  Bets, Ksenia V.;  Algozeeb, Wala Ali;  Stanford, Michael G.;  Kittrell, Carter;  Chen, Weiyin;  Salvatierra, Rodrigo V.;  Ren, Muqing;  McHugh, Emily A.;  Advincula, Paul A.;  Wang, Zhe;  Bhatt, Mahesh;  Guo, Hua;  Mancevski, Vladimir;  Shahsavari, Rouzbeh;  Yakobson, Boris I.;  Tour, James M.
收藏  |  浏览/下载:85/0  |  提交时间:2020/07/03

Harvesting energy from the environment offers the promise of clean power for self-sustained systems(1,2). Known technologies-such as solar cells, thermoelectric devices and mechanical generators-have specific environmental requirements that restrict where they can be deployed and limit their potential for continuous energy production(3-5). The ubiquity of atmospheric moisture offers an alternative. However, existing moisture-based energy-harvesting technologies can produce only intermittent, brief (shorter than 50 seconds) bursts of power in the ambient environment, owing to the lack of a sustained conversion mechanism(6-12). Here we show that thin-film devices made from nanometre-scale protein wires harvested from the microbe Geobacter sulfurreducens can generate continuous electric power in the ambient environment. The devices produce a sustained voltage of around 0.5 volts across a 7-micrometre-thick film, with a current density of around 17 microamperes per square centimetre. We find the driving force behind this energy generation to be a self-maintained moisture gradient that forms within the film when the film is exposed to the humidity that is naturally present in air. Connecting several devices linearly scales up the voltage and current to power electronics. Our results demonstrate the feasibility of a continuous energy-harvesting strategy that is less restricted by location or environmental conditions than other sustainable approaches.


A new type of energy-harvesting device, based on protein nanowires from the microbe Geobacter sulforreducens, can generate a sustained power output by producing a moisture gradient across the nanowire film using natural humidity.


  
Strain-hardening and suppression of shear-banding in rejuvenated bulk metallic glass 期刊论文
NATURE, 2020, 578 (7796) : 559-+
作者:  Papai, Gabor;  Frechard, Alexandre;  Kolesnikova, Olga;  Crucifix, Corinne;  Schultz, Patrick;  Ben-Shem, Adam
收藏  |  浏览/下载:14/0  |  提交时间:2020/07/03

Strain-hardening (the increase of flow stress with plastic strain) is the most important phenomenon in the mechanical behaviour of engineering alloys because it ensures that flow is delocalized, enhances tensile ductility and inhibits catastrophic mechanical failure(1,2). Metallic glasses (MGs) lack the crystallinity of conventional engineering alloys, and some of their properties-such as higher yield stress and elastic strain limit(3)-are greatly improved relative to their crystalline counterparts. MGs can have high fracture toughness and have the highest known '  damage tolerance'  (defined as the product of yield stress and fracture toughness)(4) among all structural materials. However, the use of MGs in structural applications is largely limited by the fact that they show strain-softening instead of strain-hardening  this leads to extreme localization of plastic flow in shear bands, and is associated with early catastrophic failure in tension. Although rejuvenation of an MG (raising its energy to values that are typical of glass formation at a higher cooling rate) lowers its yield stress, which might enable strain-hardening(5), it is unclear whether sufficient rejuvenation can be achieved in bulk samples while retaining their glassy structure. Here we show that plastic deformation under triaxial compression at room temperature can rejuvenate bulk MG samples sufficiently to enable strain-hardening through a mechanism that has not been previously observed in the metallic state. This transformed behaviour suppresses shear-banding in bulk samples in normal uniaxial (tensile or compressive) tests, prevents catastrophic failure and leads to higher ultimate flow stress. The rejuvenated MGs are stable at room temperature and show exceptionally efficient strain-hardening, greatly increasing their potential use in structural applications.


Bulk metallic glasses can acquire the ability to strain-harden through a mechanical rejuvenation treatment at room temperature that retains their non-crystalline structure.