Forschungszentrum Energiespeichertechnologien

Background: Poor health-related quality of life (HRQL) is common in heart failure (HF), but there are few data on HRQL in HF and the association between HRQL and mortality outside Western countries. Methods: We used the Kansas City Cardiomyopathy Questionnaire–12 (KCCQ-12) to record HRQL in 23 291 patients with HF from 40 countries in 8 different world regions in the G-CHF study (Global Congestive Heart Failure). We compared standardized KCCQ-12 summary scores (adjusted for age, sex, and markers of HF severity) among regions (scores range from 0 to 100, with higher score indicating better HRQL). We used multivariable Cox regression with adjustment for 15 variables to assess the association between KCCQ-12 summary scores and the composite of all-cause death, HF hospitalization, and each component over a median follow-up of 1.6 years. Results: The mean age of participants was 65 years; 61% were men; 40% had New York Heart Association class III or IV symptoms; and 46% had left ventricular ejection fraction ≥40%. Average HRQL differed between regions (lowest in Africa [mean± SE, 39.5±0.3], highest in Western Europe [62.5±0.4]). There were 4460 (19%) deaths, 3885 (17%) HF hospitalizations, and 6949 (30%) instances of either event. Lower KCCQ-12 summary score was associated with higher risk of all outcomes; the adjusted hazard ratio (HR) for each 10-unit KCCQ-12 summary score decrement was 1.18 (95% CI, 1.17–1.20) for death. Although this association was observed in all regions, it was less marked in South Asia, South America, and Africa (weakest association in South Asia: HR, 1.08 [95% CI, 1.03–1.14]; strongest association in Eastern Europe: HR, 1.31 [95% CI, 1.21–1.42]; interaction P <0.0001). Lower HRQL predicted death in patients with New York Heart Association class I or II and III or IV symptoms (HR, 1.17 [95% CI, 1.14–1.19] and HR, 1.14 [95% CI, 1.12–1.17]; interaction P =0.13) and was a stronger predictor for the composite outcome in New York Heart Association class I or II versus class III or IV (HR 1.15 [95% CI, 1.13–1.17] versus 1.09 [95% CI, [1.07–1.11]; interaction P <0.0001). HR for death was greater in ejection fraction ≥40 versus <40% (HR, 1.23 [95% CI, 1.20–1.26] and HR, 1.15 [95% CI, 1.13–1.17]; interaction P <0.0001). Conclusion: HRQL is a strong and independent predictor of all-cause death and HF hospitalization across all geographic regions, in mildly and severe symptomatic HF, and among patients with preserved and reduced ejection fraction. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03078166.

In this discussion paper we discuss our recent results on the electrodeposition of materials and in situ STM/AFM measurements which demonstrate that ionic liquids should not be regarded as neutral solvents which all have similar properties. In particular, we focus on differences in interfacial structure (solvation layers) on metal electrodes as a function of ionic liquid species. Recent theoretical and experimental results show that conventional double layers do not form on metal electrodes in ionic liquid systems. Rather, a multilayer architecture is present, with the number of layers determined by the ionic liquid species and the properties of the surface; up to seven discrete interfacial solvent layers are present on electrode surfaces, consequently there is no simple electrochemical double layer. Both the electrodeposition of aluminium and of tantalum are strongly influenced by ionic liquids: in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py1,4]TFSA, aluminium is obtained as a nanomaterial, whereas in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [EMIm]TFSA, a microcrystalline material is made. Tantalum can be deposited from [Py1,4]TFSA, whereas from [EMIm]TFSA only non-stoichiometric tantalum fluorides TaFx are obtained. It is likely that solvation layers influence these reactions.

The structure and dynamics of the interfacial layers between the extremely pure air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and Au(111) has been investigated using in situ scanning tunneling microscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and atomic force microscopy measurements. The in situ scanning tunnelling microscopy measurements reveal that the Au(111) surface undergoes a reconstruction, and at -1.2 V versus Pt quasi-reference the famous (22 × √3) herringbone superstructure is probed. Atomic force microscopy measurements show that multiple ion pair layers are present at the ionic liquid/Au interface which are dependent on the electrode potential. Upon applying cathodic electrode potentials, stronger ionic liquid near surface structure is detected: both the number of near surface layers and the force required to rupture these layers increases. The electrochemical impedance spectroscopy results reveal that three distinct processes take place at the interface. The fastest process is capacitive in its low-frequency limit and is identified with electrochemical double layer formation. The differential electrochemical double layer capacitance exhibits a local maximum at -0.2 V versus Pt quasi-reference, which is most likely caused by changes in the orientation of cations in the innermost layer. In the potential range between -0.84 V and -1.04 V, a second capacitive process is observed which is slower than electrochemical double layer formation. This process seems to be related to the herringbone reconstruction. In the frequency range below 1 Hz, the onset of an ultraslow faradaic process is found. This process becomes faster when the electrode potential is shifted to more negative potentials.

The structure of the interfacial layer(s) between the extremely pure air- and water-stable ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl) trifluorophosphate and Au(111) has been investigated using in situ scanning tunneling microscopy (STM) at electrode potentials more positive than the open circuit potential. The in situ STM measurements show that layers/islands form with increasing electrode potential. According to recently published atomic force microscopy (AFM) data the anion is adsorbed even at low anodic overvoltages and adsorption becomes slightly stronger with increasing electrode potential. Furthermore, the number of interfacial layers increases with increasing electrode potential. The present discussion paper shows that these layers are not uniform and have a structure on the nanoscale, supporting earlier results that the interface electrode/ionic liquid is highly complex. It is also shown that the addition of solutes changes this structure considerably. AFM results reveal that in the pure liquid, interfacial layers lead to a repulsive force but the addition of 10 wt% of LiCl leads to an attractive force close to the surface. These preliminary results show that solutes strongly alter the interfacial structure of the ionic liquid/ electrode interface.

Carbon capture, utilization, and storage (CCUS) is a gas injection technology that enables the storage of CO 2 underground. The aims are twofold, on one hand to reduce the emissions of CO 2 into the atmosphere and on the other hand to increase oil/gas/heat recovery. Different types of CCUS technologies and related engineering projects have a long history of research and operation in the USA. However, in China they have a short development period ca. 10 years. Unlike CO 2 capture and CO 2 -EOR technologies that are already operating on a commercial scale in China, research into other CCUS technologies is still in its infancy or at the pilot-scale. This paper first reviews the status and development of the different types of CCUS technologies and related engineering projects worldwide. Then it focuses on their developments in China in the last decade. The main research projects, international cooperation, and pilot-scale engineering projects in China are summarized and compared. Finally, the paper examines the challenges and prospects to be experienced through the industrialization of CCUS engineering projects in China. It can be concluded that the CCUS technologies have still large potential in China. It can only be unlocked by overcoming the technical and social challenges.

In this letter we show that nanocrystalline aluminium can be electrodeposited in the Lewis acidic ionic liquid based on AlCl3 (60 mol%) and 1-(2-methoxyethyl)-3-methylimidazolium chloride ([MoeMIm]Cl) (40 mol%). The study comprised cyclic voltammetry, potentiostatic polarization, and SEM and XRD measurements. The methoxy group in the side chain of the imidazolium cation significantly influences the electrodeposition pathway of Al in comparison to [EMIm]Cl/AlCl3. Cyclic voltammetry shows a significant current loop attributed to nucleation. Shiny Al layers are obtained with an average crystallite size of about 40 nm.

PURPOSE/OBJECTIVE(S): It is currently unclear whether patients with low risk breast cancer receiving adjuvant endocrine therapy need adjuvant radiation therapy after breast conserving surgery. The data of randomized trials are available. MATERIALS/METHODS: In a database search 5 randomized trials including in total 3766 mostly elderly patients with early stage breast cancer treated either with adjuvant endocrine therapy or with endocrine therapy and additional whole breast radiation after breast conserving surgery were identified. Published hazard ratios for time to local recurrence were the basis of our meta-analysis. Meta-analysis of the effect sizes on local recurrence was performed using a random effects model based on parameter estimates of log hazard ratios in Cox models and their standard errors. Furthermore, overall survival was examined. RESULTS: Adjuvant hormone therapy alone in mostly older patients with low risk breast cancer resulted in significantly shorter time to local relapse compared to radiation therapy combined with hormone therapy (Hazard Ratio: 6.8, 95% CI: 4.23-10.93, p < 0.0001) . There was no significant difference for overall survival. CONCLUSION: Additional radiation therapy to hormone therapy did improve local relapse in breast cancer patients but did not show significant impact on overall survival.

Many organisms adjust their reproductive phenology in response to climate change, but phenological sensitivity to temperature may vary between species. For example, resident and migratory birds have vastly different annual cycles, which can cause differential temperature sensitivity at the breeding grounds, and may affect competitive dynamics. Currently, however, adjustment to climate change in resident and migratory birds have been studied separately or at relatively small geographical scales with varying time series durations and methodologies. Here, we studied differential effects of temperature on resident and migratory birds using the mean egg laying initiation dates from 10 European nest box schemes between 1991 and 2015 that had data on at least one resident tit species and at least one migratory flycatcher species. We found that both tits and flycatchers advanced laying in response to spring warming, but resident tit populations advanced more strongly in relation to temperature increases than migratory flycatchers. These different temperature responses have already led to a divergence in laying dates between tits and flycatchers of on average 0.94 days per decade over the current study period. Interestingly, this divergence was stronger at lower latitudes where the interval between tit and flycatcher phenology is smaller and winter conditions can be considered more favorable for resident birds. This could indicate that phenological adjustment to climate change by flycatchers is increasingly hampered by competition with resident species. Indeed, we found that tit laying date had an additional effect on flycatcher laying date after controlling for temperature, and this effect was strongest in areas with the shortest interval between both species groups. Combined, our results suggest that the differential effect of climate change on species groups with overlapping breeding ecology affects the phenological interval between them, potentially affecting interspecific interactions.

In the present contribution we demonstrate a new testing cell, which allows simultaneous in situ optical and electrochemical investigations of passivation processes on zinc anodes in quiescent alkaline electrolytes. By combination of microscopy and galvanostatic impedance spectroscopy it was possible to detect the starting point of passive film formation, which has not been achieved so far. We found that formation of the so-called type 1 passive film is not dependent on the anodic current density. This passive film appears at electrode overpotentials of <0.15 V after an amount of zincate ions of approx. 8.2·10−4 mol cm−2 has accumulated at the anode in a 30 wt% KOH electrolyte with 2 wt% ZnO at room temperature. Consequently, the passivation of zinc in quiescent electrolyte cannot be avoided even at very low dissolution currents. On the other hand, the so-called type 2 passive film appears below the first film due to direct oxidation of zinc. At overpotentials of ≥0.15 V the direct oxidation of zinc is favored and the potential-dependent type 2 passive film appears before type 1 film is formed.

The objective of this paper was to investigate the THM-coupled responses of the storage formation and caprock, induced by gas production, CO2-EGR (enhanced gas recovery), and CO2-storage. A generic 3D planer model (20,000 × 3,000 × 100 m, consisting of 1,200 m overburden, 100 m caprock, 200 m gas reservoir, and 1,500 m base rock) is adopted for the simulation process using the integrated code TOUGH2/EOS7C-FLAC3D and the multi-purpose simulator OpenGeoSys. Both simulators agree that the CO2-EGR phase under a balanced injection rate (31,500 tons/year) will cause almost no change in the reservoir pressure. The gas recovery rate increases 1.4 % in the 5-year CO2-EGR phase, and a better EGR effect could be achieved by increasing the distance between injection and production wells (e.g., 5.83 % for 5 km distance, instead of 1.2 km in this study). Under the considered conditions there is no evidence of plastic deformation and both reservoir and caprock behave elastically at all operation stages. The stress path could be predicted analytically and the results show that the isotropic and extensional stress regime will switch to the compressional stress regime, when the pore pressure rises to a specific level. Both simulators agree regarding modification of the reservoir stress state. With further CO2-injection tension failure in reservoir could occur, but shear failure will never happen under these conditions. Using TOUGH-FLAC, a scenario case is also analyzed with the assumption that the reservoir is naturally fractured. The specific analysis shows that the maximal storage pressure is 13.6 MPa which is determined by the penetration criterion of the caprock.

Flow batteries are one option for future, low-cost stationary energy storage. We present a perspective overview of the potential cost of organic active materials for aqueous flow batteries based on a comprehensive mathematical model. The battery capital costs for 38 different organic active materials, as well as the state-of-the-art vanadium system are elucidated. We reveal that only a small number of organic molecules would result in costs close to the vanadium reference system. We identify the most promising candidate as the phenazine 3,3'-(phenazine-1,6-diylbis(azanediyl))dipropionic acid) [1,6-DPAP], suggesting costs even below that of the vanadium reference. Additional cost-saving potential can be expected by mass production of these active materials; major benefits lie in the reduced electrolyte costs as well as power costs, although plant maintenance is a major challenge when applying organic materials. Moreover, this work is designed to be expandable. The developed calculation tool (ReFlowLab) accompanying this publication is open for updates with new data.

A thorough understanding of the microscopic flow process in porous and fractured media is significant for oil and gas development, geothermal energy extraction and subsurface CO 2 storage etc. In CO 2 geological sequestration, the CO 2 is often injected at the supercritical state (scCO 2 ), which will displace the connate fluids in the pore spaces during the drainage process. However, when CO 2 injection stops, the connate brine or water flows back to displace the scCO 2 . Therefore, the configuration of migration paths in a specific reservoir plays a significant role in affecting the connectivity and storage efficiency of scCO 2 . In this paper, the two-phase (scCO 2 and water) boundary has been defined using the phase field method, and the COMSOL Multiphysics simulator is applied to study the migration of scCO 2 in porous/fractured media at the pore scale. The geological conditions of Shiqianfeng formation in the CO 2 capture and storage pilot site of the Ordos Basin in China is selected as the engineering background. Before using the actual microscopic geometry based on thin-section of Shiqianfeng sandstone, we get the general understanding on scCO 2 migration in fractured porous media that has the highly simplified configuration with circular particles, considering the impacts of wettability, geometry of formation mineral grains, interfacial tension, injection rates, and fracture geometry. Results show that the CO 2 preferential flow occurs at locations with high CO 2 flow rates and high CO 2 pore pressure. The preferential flow of scCO 2 occurs adjacent to the wall of grains while minimal or little flow takes place through the interior between the grains, considering the grains with irregular shapes. The interfacial tension of porous media plays a significant role in controlling the spatial distribution of the scCO 2 . A much lower interfacial tension results in a much thinner scCO 2 flow band with a much higher saturation. The geometry of fractures in porous media increases the complexity of the scCO 2 flow paths at the pore scale. Cited as : Liu, H., Zhu, Z., Patrick, W., Liu, J., Lei, H., Zhang, L. Pore-scale numerical simulation of supercritical CO 2 migration in porous and fractured media saturated with water. Advances in Geo-Energy Research, 2020, 4(4): 419-434, doi: 10.46690/ager.2020.04.07

BACKGROUND: The aim was to estimate the impact of individual risk factors and treatment with various disease-modifying antirheumatic drugs (DMARDs) on the incidence of myocardial infarction (MI) in patients with rheumatoid arthritis (RA). METHODS: We analysed data from 11,285 patients with RA, enrolled in the prospective cohort study RABBIT, at the start of biologic (b) or conventional synthetic (cs) DMARDs. A nested case-control study was conducted, defining patients with MI during follow-up as cases. Cases were matched 1:1 to control patients based on age, sex, year of enrolment and five cardiovascular (CV) comorbidities. Generalized linear models were applied (Poisson regression with a random component, conditional logistic regression). RESULTS: In total, 112 patients developed an MI during follow-up. At baseline, during the first 6 months of follow-up and prior to the MI, inflammation markers (erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)) but not 28-joint-count disease activity score (DAS28) were significantly higher in MI cases compared to matched controls and the remaining cohort. Baseline treatment with DMARDs was similar across all groups. During follow-up bDMARD treatment was significantly more often discontinued or switched in MI cases. CV comorbidities were significantly less often treated in MI cases vs. matched controls (36 % vs. 17 %, p < 0.01). In the adjusted regression model, we found a strong association between higher CRP and MI (OR for log-transformed CRP at follow-up: 1.47, 95 % CI 1.00; 2.16). Furthermore, treatment with prednisone ≥10 mg/day (OR 1.93, 95 % CI 0.57; 5.85), TNF inhibitors (OR 0.91, 95 % CI 0.40; 2.10) or other bDMARDs (OR 0.85, 95 % CI 0.27; 2.72) was not associated with higher MI risk. CONCLUSIONS: CRP was associated with risk of MI. Our results underline the importance of tight disease control taking not only global disease activity, but also CRP as an individual marker into account. It seems irrelevant with which class of (biologic or conventional) DMARD effective control of disease activity is achieved. However, in some patients the available treatment options were insufficient or insufficiently used - regarding DMARDs to treat RA as well as regarding the treatment of CV comorbidities.

Abstract. In this article we describe the implementation of an online-coupled gas-phase chemistry model in the turbulence-resolving PALM model system 6.0 (formerly an abbreviation for Parallelized Large-eddy Simulation Model and now an independent name). The new chemistry model is implemented in the PALM model as part of the PALM-4U (PALM for urban applications) components, which are designed for application of the PALM model in the urban environment (Maronga et al., 2020). The latest version of the Kinetic PreProcessor (KPP, 2.2.3) has been utilized for the numerical integration of gas-phase chemical reactions. A number of tropospheric gas-phase chemistry mechanisms of different complexity have been implemented ranging from the photostationary state (PHSTAT) to mechanisms with a strongly simplified volatile organic compound (VOC) chemistry (e.g. the SMOG mechanism from KPP) and the Carbon Bond Mechanism 4 (CBM4; Gery et al., 1989), which includes a more comprehensive, but still simplified VOC chemistry. Further mechanisms can also be easily added by the user. In this work, we provide a detailed description of the chemistry model, its structure and input requirements along with its various features and limitations. A case study is presented to demonstrate the application of the new chemistry model in the urban environment. The computation domain of the case study comprises part of Berlin, Germany. Emissions are considered using street-type-dependent emission factors from traffic sources. Three chemical mechanisms of varying complexity and one no-reaction (passive) case have been applied, and results are compared with observations from two permanent air quality stations in Berlin that fall within the computation domain. Even though the feedback of the model's aerosol concentrations on meteorology is not yet considered in the current version of the model, the results show the importance of online photochemistry and dispersion of air pollutants in the urban boundary layer for high spatial and temporal resolutions. The simulated NOx and O3 species show reasonable agreement with observations. The agreement is better during midday and poorest during the evening transition hours and at night. The CBM4 and SMOG mechanisms show better agreement with observations than the steady-state PHSTAT mechanism.

Abstract. The PALM model system 6.0 is designed to simulate micro- and mesoscale flow dynamics in realistic urban environments. The simulation results can be very valuable for various urban applications, for example to develop and improve mitigation strategies related to heat stress or air pollution. For the accurate modelling of urban environments, realistic boundary conditions need to be considered for the atmosphere, the local environment and the soil. The local environment with its geospatial components is described in the static driver of the model and follows a standardized format. The main input parameters describe surface type, buildings and vegetation. Depending on the desired simulation scenario and the available data, the local environment can be described at different levels of detail. To compile a complete static driver describing a whole city, various data sources are used, including remote sensing, municipal data collections and open data such as OpenStreetMap. This article shows how input data sets for three German cities were derived. Based on these data sets, the static driver for PALM can be generated. As the collection and preparation of input data sets is tedious, prospective research aims at the development of a semi-automated processing chain to support users in formatting their geospatial data.

We present a femtosecond laser pulse process that induces a texture-like surface structure on silicon wafers and optionally incorporates sulfur into the silicon lattice for emitter formation depending on the processing atmosphere. Such laser processed Black Silicon provides an easily adjustable surface roughness for good light trapping in silicon solar cells. The structure is independent of the silicon crystal orientation and is easily applied on one wafer side only. A sulfur emitter can be formed within the laser structuring process, and allows electric current extraction from a solar cell structure manufactured from this material. Then the advantage is that no further emitter formation step like diffusion is necessary compared to other Black Silicon solar cell approaches, where the Black silicon is created wet chemically. By incorporating sulfur in the silicon crystal lattice, we can show that this Black Silicon absorbs in the infrared wavelength regime. This characteristic can potentially be used to better exploit the energy in the sun spectrum. We manufacture a laser processed Black Silicon solar cell prototype without any emitter diffusion step and achieve the highest efficiency of 4.5% reported for this cell type.

In the present paper the underpotential deposition (UPD) of lithium on Au(111) from 0.5 mol L(-1) LiTFSA in the air- and water stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide, [Py(1,4)]TFSA, has been investigated by cyclic voltammetry (CV) and in situ scanning tunneling microscopy (STM). The pure [Py(1,4)]TFSA was found to be inert in the potential regime investigated. The results show that the lithium UPD on Au(111) in [Py(1,4)]TFSA begins at potentials considerably positive to the electrode potential of bulk deposition and follows a layer-by-layer mechanism with the formation of at least two monolayers. A large number of monoatomically deep pits appear when the potential reaches positive values, which is an indication that a Li-Au alloy was formed.

PURPOSE: This multicenter, randomized, crossover study compared preference, ease of use, acceptability, satisfaction, and safety of repeated subcutaneous (SC) self-administrations with prefilled pens and prefilled syringes delivering methotrexate (MTX), in patients with rheumatoid arthritis (RA). PATIENTS AND METHODS: The study (ClinicalTrials.gov number NCT01793259) enrolled 120 patients requiring initiation or intensification of MTX therapy for RA. Patients were randomized to receive the test drug, a prefilled pen (Metex(®) PEN/Metoject(®) PEN), or the reference drug, a prefilled syringe (Metex(®)/Metoject(®)), at doses of 15, 17.5, or 20 mg MTX SC once a week for 3 weeks. This was followed by receipt of the reference drug (prefilled syringe) or the test drug (prefilled pen) in a crossover design, with each patient serving as his/her own control. Questionnaires regarding patient preference, the Self-Injection Assessment Questionnaire (SIAQ), and diaries regarding local tolerability were used to document outcomes. RESULTS: Overall patient preference for the MTX prefilled pen was 75% (P<0.0001). In a six-item questionnaire, 73% to 76% of the patients preferred the prefilled pen in relation to use, acceptability, and satisfaction, and 67% of the patients confirmed that it did not take much effort to overcome SC self-injection with the pen. The SIAQ showed no clinical differences, in any domain scores, between both devices. Overall patient attitude towards self-injection at baseline was positive, as was patient experience with both devices during the study. As well, 92% of physicians and study nurses indicated that they would recommend the MTX prefilled pen to patients for future MTX treatment. The formulations were generally well tolerated. CONCLUSION: SC self-injection of MTX with a prefilled pen was generally preferred, by patients with RA, over a prefilled syringe with regard to use, acceptability, and satisfaction. This is supported by the strong appreciation of their attending study nurses and physicians, for its convenience.

Abstract Large‐scale underground hydrogen storage (UHS) provides a promising method for increasing the role of hydrogen in the process of carbon neutrality and energy transition. Of all the existing storage deposits, salt caverns are recognized as ideal sites for pure hydrogen storage. Evaluation and optimization of site selection for hydrogen storage facilities in salt caverns have become significant issues. In this article, the software CiteSpace is used to analyze and filter hot topics in published research. Based on a detailed classification and analysis, a “four‐factor” model for the site selection of salt cavern hydrogen storage is proposed, encompassing the dynamic demands of hydrogen energy, geological, hydrological, and ground factors of salt mines. Subsequently, 20 basic indicators for comprehensive suitability grading of the target site were screened using the analytic hierarchy process and expert survey methods were adopted, which provided a preliminary site selection system for salt cavern hydrogen storage. Ultimately, the developed system was applied for the evaluation of salt cavern hydrogen storage sites in the salt mines of Pingdingshan City, Henan Province, thereby confirming its rationality and effectiveness. This research provides a feasible method and theoretical basis for the site selection of UHS in salt caverns in China.

Abstract. Including radiative transfer processes within the urban canopy layer into microscale urban climate models (UCMs) is essential to obtain realistic model results. These processes include the interaction of buildings and vegetation with shortwave and longwave radiation, thermal emission, and radiation reflections. They contribute differently to the radiation budget of urban surfaces. Each process requires different computational resources and physical data for the urban elements. This study investigates how much detail modellers should include to parameterize radiative transfer in microscale building-resolving UCMs. To that end, we introduce a stepwise parameterization method to the Parallelized Large-eddy Simulation Model (PALM) system 6.0 to quantify individually the effects of the main radiative transfer processes on the radiation budget and on the flow field. We quantify numerical simulations of both simple and realistic urban configurations to identify the major and the minor effects of radiative transfer processes on the radiation budget. The study shows that processes such as surface and vegetation interaction with shortwave and longwave radiation will have major effects, while a process such as multiple reflections will have minor effects. The study also shows that radiative transfer processes within the canopy layer implicitly affect the incoming radiation since the radiative transfer model is coupled to the radiation model. The flow field changes considerably in response to the radiative transfer processes included in the model. The study identified those processes which are essentially needed to assure acceptable quality of the flow field. These processes are receiving radiation from atmosphere based on the sky-view factors, interaction of urban vegetation with radiation, radiative transfer among urban surfaces, and considering at least single reflection of radiation. Omitting any of these processes may lead to high uncertainties in the model results.