Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ch4”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Guest Molecule Exchange Kinetics for the 2012 Ignik Sikumi Gas Hydrate Field Trial

A commercially viable technology for producing methane from natural gas hydrate reservoirs remains elusive. Short-term depressurization field tests have demonstrated the potential for producing natural gas via dissociation of the clathrate structure, but the long-term performance of the depressurization technology ultimately requires a heat source to sustain the dissociation. A decade of laboratory experiments and theoretical studies have demonstrated the exchange of pure CO2 and N2-CO2 mixtures with CH4 in sI gas hydrates, yielding critical information about molecular mechanisms, recoveries, and exchange kinetics. Findings indicated the potential for producing natural gas with little to no production of water and rapid exchange kinetics, generating sufficient interest in the guest-molecule exchange technology for a field test. In 2012 the U.S. DOE/NETL, ConocoPhillips Company, and Japan Oil, Gas and Metals National Corporation jointly sponsored the first field trial of injecting a mixture of N2-CO2 into a CH4-hydrate bearing formation beneath the permafrost on the Alaska North Slope. Known as the Ignik Sikumi #1 Gas Hydrate Field Trial, this experiment involved three stages: 1) the injection of a N2-CO2 mixture into a targeted hydrate-bearing layer, 2) a 4-day pressurized soaking period, and 3) a sustained depressurization and fluid production period. Data collected during the three stages of the field trial were made available after an extensive quality check. These data included continuous temperature and pressure logs, injected and recovered fluid compositions and volumes. The Ignik Sikumi #1 data set is extensive, but contains no direct evidence of the guest-molecule exchange process. This investigation is directed at using numerical simulation to provide an interpretation of the collected data. A numerical simulator, STOMP-HYDT-KE, was recently completed that solves conservation equations for energy, water, mobile fluid guest molecules, and hydrate guest molecules, for up to three gas hydrate guest molecules: CH4, CO2, and N2. The independent tracking of mobile fluid and hydrate guest molecules allows for the kinetic exchange of guest molecules between the mobile fluids and hydrate. The particular interest of this numerical investigation is to determine whether kinetic exchange parameters, determined from laboratory-scale experiments, are directly applicable to interpreting the Ignik Sikumi #1 data.

Alaska North Slope↗
DOE OSTI2017

Balloon-Borne Full-Column Greenhouse Gas Profiling Field Campaign Report

The vertical distributions of CO2, CH4, and other gases provide important constraints for the determination of terrestrial and ocean sources and sinks of carbon and other biogeochemical processes in the Earth system. The DOE Biological and Environmental Research Program (DOE-BER) and the NOAA Earth System Research Laboratory (NOAA-ESRL) collaborate to quantify the vertically resolved distribution of atmospheric carbon-cycle gases (CO2, and CH4) within approximately 99% of the atmospheric column at the DOE ARM Southern Great Plains Facility in Oklahoma. In 2015, flights were delayed while research at NOAA focused on evaluating sources of systematic errors in the gas collection and analysis system and modifying the sampling system to provide duplicate air samples in a single flight package. In 2017, we look forward to proposing additional sampling and analysis at ARM-SGP (and other sites) that characterize the vertical distribution of CO2 and CH4 over time and space.

Community Earth System Model, Southern Great Plain↗
DOE OSTI2023

Methane Emissions Produced by Pneumatic Devices and Produced Water Tanks on Natural Gas Wellsites

In recent years, more scrutiny has been placed on the release of greenhouse gasses (GHGs) by the oil and gas industry in North America as climate concerns increase. In the coming years, stricter regulations proposed by the Environmental Protection Agency (EPA) concerning the release of GHGs will further direct attention to GHG emissions quantification, modeling, and overall reduction. Active natural gas wellsites employ production equipment that routinely emits methane during normal operation. Production equipment often includes, but is not limited to, gas production units (GPUs), pneumatic controllers (PCs) and actuators powered by produced natural gas, and produced water storage tanks. This work details direct methane emission measurements taken at active natural gas wellsites originating from intermittent pneumatic controllers and produced water storage tanks. Efforts to model methane flows originating from these sources are also detailed, and those results are compared to direct measurement. The direct methane emissions measurement campaign collected flow data from two active dry wellsites in the Marcellus shale region. These measurement campaigns captured, in total, several weeks of continuous data from these sites. Data included multiple pneumatic device vent flowrate channels, a single channel monitoring total emissions vented from the produced water storage tanks, and corresponding site weather data. Periodic composition measurements were taken from flows vented from produced water tanks. Computational modeling efforts attempted to mimic a given site’s methane emissions behavior given limited input parameters. Direct measurement data and simulation data yielded, through reduction and analysis, apparent methane emissions factors, statistics on pneumatic device actuation events, important relationships between GPU parameters and pneumatic device actuation events, produced water storage tank vent flows and flow compositions, and parameters most contributing to the magnitude and frequency of these fugitive methane emissions. Measurements, considering data from a 72hr period, produced PC emissions factors from 0.008 to 0.03 SCFH per device with an average device emitting 0.026 SCFH at the first site. The second site produced PC emissions factors spanning from 0.05 to 25.47 SCFH with an average device emitting 1.93 SCFH not including the 25.47 SCFH device, which was assumed to be malfunctioning. Two unique water tank emission measurements were made, 618 g CH4 per hour and 32.6 g CH4 per hour. On a water basis, the water tank emissions factors were 0.66 and 0.042 kg CH4 per bbl of water, respectively.

03 NATURAL GAS↗
DOE OSTI2019

SPRUCE Does dissolved organic matter or solid peat fuel anerobic respiration in peatlands?: Supporting Data

Hopple et al. (2019) investigated whether, as a primary substrate - dissolved organic matter (DOM) or solid peat - was driving anaerobic respiration at surface and at deep depth increments within two bogs and a poor fen in northern Minnesota. To address this question, they used a combination of soil laboratory incubations, as well as in-situ analyses of porewater dissolved organic carbon (DOC) concentrations and specific UV absorbance (SUVA) measurements. Soil samples were collected in June 2013 and July 2014, while porewater samples were taken in July 2013. Data provided include: porewater DOC concentration and SUVA values, soil CH4 and CO2 potential production rates from peat samples exposed to varying DOM concentrations, and soil CH4 and CO2 potential production rates.These data are provided in support of the publication: Does dissolved organic matter or solid peat fuel anerobic respiration in peatlands? (Hopple et al., 2019). This dataset contains four files in comma separate (*.csv) format.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

New Generation Flask Sampling Technology Final Report

Scientists are turning their focus to the Arctic, site of one of the strongest climate change signals. A new generation of technologies is required to function within that harsh environment, chart evolution of its trace gases and provide new kinds of information for models of the atmosphere. Our response to the solicitation tracks how global atmospheric monitoring was launched more than a half century ago; namely, acquisition of discrete samples of air by flask and subsequent analysis in the laboratory. AOS is proposing to develop a new generation of flask sampling technology. It will enable the new Arctic programs to begin with objective high density sampling of the atmosphere by UAS. The Phase I program will build the prototype flask technology and show that it can acquire and store mol fractions of CH4 and CO2 and value of δ13C with good fidelity. A CAD model will be produced for the entire platform including a package with 100 flasks and the airframe with auto-pilot, electronic propulsion and ground-to-air communications. A mobile flask analysis station will be prototyped in Phase I and designed to final form in Phase II. It expends very small sample per analysis and will interface directly to the flask package integrated permanently into the UAS fuselage. Commercial Applications and Other Benefits: • The New Generation Flask Sampling Technology able to provide a hundred or more samples of air per UAS mission. • A mobile analysis station expending far less sample than the existing ones and small enough to be stationed at the remote sites of Arctic operations. • A new form of validation for continuous trace gas observations from all platforms including the small UAS. • Further demonstration to potential customers of the AOS capabilities to invent, build, deploy and exploit entire platforms for observations of Earth’s atmosphere and ocean. Key Words: Flask Sampler, Mobile Analysis Station, Trace Gas, CO2, CH4, δC13, UAS, Baseline Airborne Observatory, Arctic, Climate Change. Summary for Members of Congress: The air, land and sea of the Arctic combine to produce a large climate change signal. AOS is proposing to develop unmanned airborne technologies able to begin prompt, objective observations of the signal’s atmospheric component.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

SPRUCE Stability of Peatland Carbon to Rising Temperatures: Supporting Data

This data set reports the results of extensive field measurements and laboratory analyses of samples from the SPRUCE experiment. Results indicate that ecosystem-scale warming of over 2 m of peat exponentially increased CH4 emissions —but not ecosystem respiration of CO2. Multiple lines of evidence, including incubations and in situ analyses of 14C, dissolved gases, and microbial community metabolic potential, indicate that CH4 emissions increased due to surface processes and not degradation of deeper buried carbon. The supporting data provided include the summarized and aggregated data used to generate the six figures in the main text of the paper and the 12 supplementary figures.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

SPRUCE Geochemical Changes in Porewater from Northern Peatlands at Multiple Depths in Field Samples and over Time in Peat Incubations

This data set reports the results of the analysis of dissolved organic matter (DOM) in porewater samples collected from multiple depths in northern peatlands and during laboratory peat incubations to characterize the gain or loss of specific chemical moieties (e.g. CH2, H2, CH2O, etc.) that may be attributed to microbial degradation. During incubations, CO2 and CH4 concentrations and stable isotopes were determined by isotope ratio mass spectrometry. Porewater samples were collected from the S1 Bog (April 2015), a Sphagnum-dominated site at northern Minnesota peatland in the Marcell Experimental Forest, using permanently-installed piezometers, which provided profiles from the watertable surface to 200 cm depth. This is the site of the SPRUCE experiment. Porewater and peat samples were collected in July 2015 from an additional Sphagnum-dominated site within Stordalen Mire, Sweden, a palsa mire underlain by thawing permafrost, using perforated stainless steel tubes that were inserted into the peat to the desired depths (13 cm and 32 cm). Porewater samples were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS) followed by Kendrick mass transform analysis. The Kendrick mass (i.e., Kendrick 1963) transform analysis identifies the gain or loss of specific chemical moieties (e.g. CH2, H2, CH2O, etc.) via mass differences, and was used to infer potential microbial degradation pathways by which compounds were consumed in these samples. Increasing depth would suggest more degradation of DOM with the greater length of time for peat accumulation and similarly, with increasing length of peat incubation. During incubations, CO2 and CH4 concentrations and stable isotopes were determined by isotope ratio mass spectrometry. There are four files provided in comma separated value (*.csv) format.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Biogenic carbon fluxes from global agricultural production and consumption

Quantification of biogenic carbon fluxes from agricultural lands is needed to generate comprehensive bottom-up estimates of net carbon exchange for global and regional carbon monitoring. We estimated global agricultural carbon fluxes associated with annual crop net primary production (NPP), harvested biomass, and consumption of biomass by humans and livestock. These estimates were combined for a single estimate of net carbon exchange (NCE) and spatially distributed to 0.05 degree resolution using MODIS satellite land cover data. Global crop NPP in 2011 was estimated at 5.25 ± 0.46 Pg C yr-1, of which 2.05 ± 0.05 Pg C yr-1 was harvested and 0.54 Pg C yr-1 was collected from crop residues for livestock fodder. Total livestock feed intake in 2011 was 2.42 ± 0.21 Pg C yr-1, of which 2.31 ± 0.21 Pg C yr-1 was emitted as CO2, 0.07 ± 0.01 Pg C yr-1 was emitted as CH4, and 0.04 Pg C yr-1 was contained within milk and egg production. Livestock grazed an estimated 1.27 Pg C yr-1 in 2011, which constituted 52.4% of total feed intake. Global human food intake was 0.57 ± 0.03 Pg C yr-1 in 2011, the majority of which is respired as CO2. Completed global cropland carbon budgets accounted for the ultimate use of ca. 80% of harvested biomass. The spatial distribution of these fluxes may be used for global carbon monitoring, estimation of regional uncertainty, and for use as input to Earth system models.

Carbon flux, croplands, livestock, MODIS↗
DOE OSTI2016

Mitigation of methane emissions in cities: How new measurements and partnerships can contribute to emissions reduction strategies

Cities generate 70% of anthropogenic greenhouse gas emissions, a fraction that is grow-ing with global urbanization. While cities play an important role in climate change mitigation, there has been little focus on reducing urban methane (CH4) emissions. Here, we develop a conceptual framework for CH 4 mitigation in cities by describing emission processes, the role of measurements, and a need for new institutional partnerships. Urban CH 4 emissions are likely to grow with expanding use of natural gas and organic waste disposal systems in growing population centers; however, we currently lack the ability to quantify this increase. We also lack systematic knowledge of the relative contribution of these distinct source sectors on emissions. We present new observations from four North American cities to demonstrate that CH4 emissions vary in magnitude and sector from city to city and hence require different mitigation strategies. Detections of fugitive emissions from these systems suggest that current mitiga- tion approaches are absent or ineffective. These findings illustrate that tackling urban CH 4 emissions will require research efforts to identify mitigation targets, develop and implement new mitigation strategies, and monitor atmospheric CH 4 levels to ensure the success of mitigation efforts. This research will require a variety of techniques to achieve these objectives and should be deployed in cities globally. In conclusion, we suggest that metropolitan scale partnerships may effectively coordinate systematic measurements and actions focused on emission reduction goals.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Large CO 2 and CH 4 emissions from polygonal tundra during spring thaw in northern Alaska: Spring Pulse Emission

The few prethaw observations of tundra carbon fluxes suggest that there may be large spring releases, but little Is lmown about the scale and underlying mechanisms of this phenomenon. To address these questions, we combined ecosystem eddy flux measurements from two towers near Barrow, Alaska, with mechanistic soil-core thawing experiment During a 2week period prior to snowmelt In 2014, large fluxes were measured, reducing net summer uptake of CO2 by 46% and adding 6% to cumulative CH4 emissions. Emission pulses were linked to unique rain-on-snow events enhancing soli cracking. Controlled laboratory experiment revealed that as surface Ice thaws, an immediate, large pulse of trapped gases Is emitted. These results suggest that the Arctic C02 and CH4 spring pulse is a delayed release of biogenic gas production from the previous fall and that the pulse can be large enough to offset a significant fraction of the moderate Arctic tundra carbon sink.

Raz-Yaseef, Naama↗
DOE OSTI2021

Rhodium Single–Atom Catalysts on Titania for Reverse Water Gas Shift Reaction Explored by First Principles Mechanistic Analysis and Compared to Nanoclusters

The thermocatalytic reduction of CO2 by H2 often proceeds via two competing reaction mechanisms—the reverse water gas shift reaction (rWGSR, CO2 + H2 ⇌ CO + H2O) and methanation (CO2 + 4H2 ⇌ CH4 + 2H2O). Atomically dispersed Rh1 catalysts on TiO2 show high selectivity toward the rWGSR compared with larger Rh nanoclusters, but the origin of this size-dependent selectivity has not been fully explained. Here we report density functional theory (DFT) calculations and microkinetic simulations that clarify the Rh1 active sites and rWGSR pathway on anatase TiO2(101), as well as the high rWGSR selectivity of Rh1 compared with supported Rhx (x = 2–8 atoms) nanoclusters. DFT-computed formation energies, vibrational frequency analysis, and microkinetic modeling suggest three plausible active sites: Rh1 on titania (Rh1/TiO2(101)), Rh1 with a nearby hydroxyl group (Rh1OH/TiO2(101)), and Rh1 near an oxygen vacancy at a three-fold coordinated site (Rh1 near O3cvac). Predicted turnover frequencies and apparent activation barriers for Rh1 indicate a faster reaction involving CO2 dissociation assisted by a support oxygen vacancy via Rh1 near O3cvac, as well as slower reactions involving Rh1OH/TiO2(101) or Rh1/TiO2(101) through a COOH intermediate. Furthermore, these Rh1 sites are selective toward CO rather than CH4 because of the weak adsorption of CO, large barrier for C-O bond dissociation, and the lack of nearby metal sites for H2 dissociation, in contrast to Rhx nanoclusters, including Rh2 dimers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Modeling CH 4 and CO 2 cycling using porewater stable isotopes in a thermokarst bog in Interior Alaska: results from three conceptual reaction networks

Quantifying rates of microbial carbon transformation in peatlands is essential for gaining mechanistic understanding of the factors that influence methane emissions from these systems, and for predicting how emissions will respond to climate change and other disturbances. In this study, we used porewater stable isotopes collected from both the edge and center of a thermokarst bog in Interior Alaska to estimate in situ microbial reaction rates. We expected that near the edge of the thaw feature, actively thawing permafrost and greater abundance of sedges would increase carbon, oxygen and nutrient availability, enabling faster microbial rates relative to the center of the thaw feature. We developed three different conceptual reaction networks that explained the temporal change in porewater CO2, CH4, δ13C-CO2 and δ13C-CH4. All three reaction-network models included methane production, methane oxidation and CO2 production, and two of the models included homoacetogenesis — a reaction not previously included in isotope-based porewater models. All three models fit the data equally well, but rates resulting from the models differed. Most notably, inclusion of homoacetogenesis altered the modeled pathways of methane production when the reaction was directly coupled to methanogenesis, and it decreased gross methane production rates by up to a factor of five when it remained decoupled from methanogenesis. The ability of all three conceptual reaction networks to successfully match the measured data indicate that this technique for estimating in-situ reaction rates requires other data and information from the site to confirm the considered set of microbial reactions. Despite these differences, all models indicated that, as expected, rates were greater at the edge than in the center of the thaw bog, that rates at the edge increased more during the growing season than did rates in the center, and that the ratio of acetoclastic to hydrogenotrophic methanogenesis was greater at the edge than in the center. In both locations, modeled rates (excluding methane oxidation) increased with depth. A puzzling outcome from the effort was that none of the models could fit the porewater dataset without generating “fugitive” carbon (i.e., methane or acetate generated by the models but not detected at the field site), indicating that either our conceptualization of the reactions occurring at the site remains incomplete or our site measurements are missing important carbon transformations and/or carbon fluxes. This model–data discrepancy will motivate and inform future research efforts focused on improving our understanding of carbon cycling in permafrost wetlands.

13CH4↗
DOE OSTI2013

Impact of biochar application on nitrogen nutrition of rice, greenhouse-gas emissions and soil organic carbon dynamics in two paddy soils of China

Two field microcosm experiments and 15N labeling techniques were used to investigate the first-year effects of biochar addition on rice N nutrition and GHG emissions in an Inceptisol and an Ultisol. Biochar N bioavailability and effect of biochar on fertilizer nitrogen-use efficiency (NUE) were studied by 15N-enriched wheat biochar (7.8803 atom% 15N) and fertilizer urea (5 atom% 15N) (Experiment I). Corn biochar and corn stalks were applied at 12 Mg ha-1 to study their effects on GHG emissions (Experiment II). Biochar had no significant impact on rice production and less than 2% of the biochar N was available to plants in the first season. Biochar addition increased soil C and N contents and decreased urea NUE.. Seasonal cumulative CH4 emissions with biochar were similar to the controls, but significantly lower than the local practice of straw amendment. Soil emissions of N2O with biochar amendment were similar to the control in the acidic Ultisol, but significantly higher in the slightly alkaline Inceptisol. Carbon-balance calculations found no major losses of biochar-C. Low bio-availability of biochar N did not make a significant impact on rice production or N nutrition during the first year.. Replacement of straw amendments with biochar could decrease CH4 emissions and increase SOC stocks.

agriculture↗
DOE OSTI2019

Sandwiched SiO 2 @Ni@ZrO 2 as a coke resistant nanocatalyst for dry reforming of methane

Design active and coke resistant Ni based catalysts is critical for implementation of dry reforming of methane technology. In this work, coke resistant SiO 2 @Ni@ZrO 2 catalyst has been successfully prepared through precipitation of nickel nitrate with ammonia onto silica spheres, followed by coating with porous ZrO 2 shell. Through thermal treatment in air and hydrogen, nickel nanoparticles with size of 6 nm were sandwiched between silica core and zirconia shell. The ZrO 2 coated Ni catalyst exhibited a high activity of (similar to)13.0 mol CH4 per gram of Ni per hour for methane dry reforming at 700 degrees C, which is more than 6 times higher than that of SiO 2 @Ni catalyst under the same reaction condition. The SiO 2 @Ni@ZrO 2 catalyst is also coke resistant as no carbon formation was observed for methane dry reforming at 700 degrees C for 20 h. As a comparison, carbon nanotubes formed over SiO 2 @Ni catalyst during dry reforming reaction with a coking rate of 0.019 g of carbon formed per gram of catalyst per hour. Operando XANES/EXAFS study of SiO 2 @Ni@ZrO 2 catalyst confirmed metallic Ni phase during methane dry reforming from 400 to 800 degrees C. Theoretical calculations suggests that ZrO 2 stabilized Ni clusters lowers the highest dissociation energy barrier of CH 4 and CO 2 by 1.37 and 2.56 eV comparing to bulk Ni, increasing dry reforming activity on SiO 2 @Ni@ZrO 2 catalyst. Furthermore, the higher binding energy of CO 2 over CH4 on SiO 2 @Ni@ZrO 2 leads to enrichment of CO 2 on catalyst surface, which mitigates coke formation

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Evolution of PTCDA-derived seeds prior to graphene nanoribbon growth on Ge(001)

The synthesis of graphene nanoribbons (GNRs) can be realized via CH4 chemical vapor deposition (CVD) on substrates such as Ge(001) that promote highly anisotropic growth kinetics. Small polycyclic aromatic hydrocarbons (PAHs) are first sublimed onto Ge near room temperature to form graphene-like seeds that subsequently initiate GNR growth with CH4 exposure at 1173 K. The behaviors of PAHs in the time in between their sublimation onto Ge and GNR growth are unclear. Here, we study an archetypical PAH, perylene-3,4,9,10-tetracarboxyl acid dianhydride (PTCDA), on Ge(001) using both scanning tunneling microscopy (STM) and density functional theory (DFT) to characterize PAH conformation, surface diffusivity, and clustering, versus temperature. PTCDA becomes mobile above 673 K (consistent with a DFT calculated diffusion barrier of 2.01 eV). The mobile PTCDA molecules meet, cluster, and fuse at Ge step edges. These clusters have an apparent height of 0.4 nm, similar to small graphene islands, and grow laterally with increasing temperature – reaching 1.2 – 2.1 nm in width at 1173 K, consistent with the seed size extrapolated from CVD experiments. These results provide a plausible picture for how PTCDA forms seeds for anisotropic GNR CVD and show that PAHs with reduced surface diffusivity and inter-molecular reactivity are needed to enable more monodisperse PAH-seeded GNR synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Understanding the contribution of non-carbon dioxide gases in deep mitigation scenarios

The combined 2010 emissions of methane (CH4), nitrous oxide (N2O) and the fluorinated gasses (F-gas) account for about 20-30% of total emissions and about 30% of radiative forcing. At the moment, most studies looking at reaching ambitious climate targets project the emission of carbon dioxide (CO2) to be reduced to zero (or less) by the end of the century. As for non-CO2 gases, the mitigation potential seem to be more constrained, we find that by the end of the century in the current deep mitigation scenarios non-CO2 emissions could form the lion’s share of remaining greenhouse gas emissions. In order to support effective climate policy strategies, in this paper we provide a more in-depth look at the role of non-CO2¬ emission sources (CH4, N2O and F-gases) in achieving deep mitigation targets (radiative forcing target of 2.8 W/m2 in 2100). Specifically, we look at the sectorial mitigation potential and the remaining non-CO2 emissions. By including a set of different models, we provide some insights into the associated uncertainty. Most of the remaining methane emissions in 2100 in the climate mitigation scenario come from the livestock sector. Strong reductions are seen in the energy supply sector across all models. For N2O, less reduction potential is seen compared to methane and the sectoral differences are larger between the models. The paper shows that the assumptions on remaining non-CO2 emissions are critical for the feasibility of reaching ambitious climate targets and the associated costs.

Gernaat, David↗