Ground-Based Mobile Measurements to Track Urban Methane Emissions from Natural Gas in 12 Cities across Eight Countries

To mitigate methane emission from urban natural gas distribution systems, it is crucial to understand local leak rates and occurrence rates. To explore urban methane emissions in cities outside the U.S., where significant emissions were found previously, mobile measurements were performed in 12 cities across eight countries. The surveyed cities range from medium size, like Groningen, NL, to large size, like Toronto, CA, and London, UK. Furthermore, this survey spanned across European regions from Barcelona, ES, to Bucharest, RO. The joint analysis of all data allows us to focus on general emission behavior for cities with different infrastructure and environmental conditions. We find that all cities have a spectrum of small, medium, and large methane sources in their domain. The emission rates found follow a heavy-tailed distribution, and the top 10% of emitters account for 60-80% of total emissions, which implies that strategic repair planning could help reduce emissions quickly. Furthermore, we compare our findings with inventory estimates for urban natural gas-related methane emissions from this sector in Europe. While cities with larger reported emissions were found to generally also have larger observed emissions, we find clear discrepancies between observation-based and inventory-based emission estimates for our 12 cities.

Hydrogen emissions from the hydrogen value chain-emissions profile and impact to global warming

Future energy systems could rely on hydrogen (H₂) to achieve decarbonisation and net-zero goals. In a similar energy landscape to natural gas, H₂ emissions occur along the supply chain. It has been studied how current gas infrastructure can support H₂, but there is little known about how H₂ emissions affect global warming as an indirect greenhouse gas. In this work, we have estimated for the first time the potential emission profiles (g CO_2eq/MJ H_2,HHV) of H₂ supply chains, and found that the emission rates of H₂ from H₂ supply chains and methane from natural gas supply are comparable, but the impact on global warming is much lower based on current estimates. This study also demonstrates the critical importance of establishing mobile H₂ emission monitoring and reducing the uncertainty of short-lived H₂ climate forcing so as to clearly address H₂ emissions for net-zero strategies.

Effect of superfine pulverization of powdered activated carbon on adsorption of carbamazepine in natural source waters

The purpose of this study is to investigate adsorptive removal of carbamazepine from natural source waters by superfine pulverized powdered activated carbon. Superfine pulverization is becoming an increasingly attractive approach to decrease the diffusion path of a target adsorbate molecule and improve the overall the kinetics of activated carbon adsorption. Here we report the impact of pulverization on powdered activated carbon characteristics, and carbamazepine adsorption behavior in distilled and deionized water and natural organic matter solutions. The superfine pulverization decreased the particle size of activated carbon by 50 folds and the specific surface area by 24%. In addition, the micropore volume of the activated carbon decreased from 0.23 cm³/g to 0.14 cm³/g, while mesopore and macropore volumes increased from 0.15 cm³/g and 0.11 cm³/g to 0.18 cm³/g and 0.48 cm³/g, respectively. In terms of surface chemistry, the oxygen and iron contents of the activated carbon increased notably after pulverization. Despite the decrease in surface area and increase in surface polarity, the pulverization improved the adsorption kinetics especially for short contact times i.e., < 6-h. In general, the dissolved organic carbon concentration negatively influenced the kinetic advantage of superfine pulverized activated carbon. Isotherm results indicated that the parent adsorbent has a higher adsorption capacity than superfine activated carbon in distilled and deionized water and in natural waters. This was attributed to the losses in specific surface area and favorable sorption sites inside micropores. Our literature analysis indicated that unlike the small molecular weight hydrophilic organic compounds, the pseudo-equilibrium adsorption capacity could be increased or at least not deteriorated for hydrophobic molecules (K_ow > 3). Therefore, superfine pulverization of PAC can serve as a promising approach to remove micropollutants from natural source waters with a kinetic advantage.

Carbon isotopic characterisation and oxidation of UK landfill methane emissions by atmospheric measurements

Biological oxidation of methane in landfill cover material can be calculated from the carbon isotopic signature (δ¹³C_CH4) of emitted CH_4. Enhanced microbial consumption of methane in the aerobic portion of the landfill cover is indicated by a shift to heavier (less depleted) isotopic values in the residual methane emitted to air. This study was conducted at four landfill sites in southwest England. Measurement of CH₄ using a mobile vehicle mounted instrument at the four sites was coupled with Flexfoil bag sampling of ambient air for high-precision isotope analysis. Gas well collection systems were sampled to estimate landfill oxidised proportion. Closed or active status, seasonal variation, cap stripping and site closure impact on landfill isotopic signature were also assessed. The δ¹³C_CH4 values ranged from -60 to -54‰, with an average value of -57 ± 2‰. Methane emissions from active cells are more depleted in ¹³C than closed sites. Methane oxidation, estimated from the isotope fractionation, ranged from 2.6 to 38.2%, with mean values of 9.5% for active and 16.2% for closed landfills, indicating that oxidised proportion is highly site specific.

Quantification of methane emissions from UK biogas plants

The rising number of operational biogas plants in the UK brings a new emissions category to consider for methane monitoring, quantification and reduction. Minimising methane losses from biogas plants to the atmosphere is critical not only because of their contribution of methane to global warming but also with respect to the sustainability of renewable energy production. Mobile greenhouse gas surveys were conducted to detect plumes of methane emissions from the biogas plants in southern England that varied in their size, waste feed input materials and biogas utilization. Gaussian plume modelling was used to estimate total emissions of methane from ten biogas plants based on repeat passes through the plumes. Methane emission rates ranged from 0.1 to 58.7 kg CH₄ hr^-1, and the percentage of losses relative to the calculated production rate varied between 0.02 and 8.1%. The average emission rate was 15.9 kg CH₄ hr^-1, and the average loss was 3.7%. In general, methane emission rates from smaller farm biogas plants were higher than from larger food waste biogas plants. We also suggest that biogas methane emissions may account for between 0.4 and 3.8%, with an average being 1.9% of the total methane emissions in the UK excluding the sewage sludge biogas plants.

Delivery of healthy infant during hemodialysis session

Acute renal failure secondary to bilateral ureteral obstruction in pregnancy is rare. We describe a case of acute renal failure secondary to bilateral ureteral obstruction. A 27 year-old woman at 35 weeks' gestation was referred to our hospital with a diagnosis of acute renal failure. The patient had been well until four days earlier, when she developed an abrupt anuria. She had been administrated excessive amounts of fluids, and unresponsive to parenteral furosemide. She had mild pitting oedema and an S3 gallop with crackles in the lungs. The uterus was enlarged to the expected size with a cervical dilatation of 2 cm in diameter. Her serum creatinine level was 7.0 mg/dl. Renal ultrasound showed bilateral hydronephrosis of severe degree. The patient was immediately hemodialyzed for advanced renal failure with hypervolemia, and a healthy infant was born at the third hour of the HD session without any complication. On the next day, her urine volume was 200 ml/day and serum creatinine level was 6.8 mg/dl. For this reason, the patient underwent cystoscopy and ureteral stents were inserted bilaterally. There was no evidence of ureteral stones or obstructive lesions. After the stenting, the urine volume increased and serum creatinine was decreased gradually to normal level at the seventh day of postpartum. Two weeks later ureteral stents were removed and both infant and patient were completely healthy. To the best of our knowledge, this is the first case of delivery of an infant during a haemodialysis session.

QT/corrected QT (QTc) intervals and QT/QTc dispersions in children with chronic renal failure

We aimed to examine QT/corrected QT (QTc) intervals, QT/QTc dispersions (QTD/QTcD) and also the effect of different clinical and laboratory variables on these parameters in children with chronic renal failure. Serum biochemistry, 12-lead electrocardiogram, telecardiogram, and echocardiography were performed in 50 children with chronic renal failure (23 female and 27 male; aged 12.3+/-3.6 years, range 5 to 20 years). None of them had symptoms related to arrhythmias. When compared with a control group (372 children, aged 7 to 18 years, mean 12.4+/-2.6) patients with chronic renal failure had greater QT/QTc intervals and QT/QTc dispersion values (Patient: QT = 360.9+/-53.3; QTc = 438.5+/-33.2; QTD = 42.4+/-20.8; QTcD = 57.5+/-23.8;

CONTROL

QT = 325.9+/-24.1; QTc = 398.7+/-19.7; QTD = 29.9+/-10.2; QTcD = 47.3+/-16.6; P<0.01). QT, QTc, and QTcD values were significantly greater in patients who had renal failure duration longer than 2 years. Patients who had impaired left ventricular systolic function on echocardiogram had greater QTc, QTD, and QTcD values. It was found that sex, cardiomegaly on chest X-ray, and left ventricular hypertrophy on echocardiogram were not related to these parameters. It is concluded that, impaired cardiac systolic function and longer renal failure duration are related to an increase in QT, QTc, QTD, and QTcD values and hence these variables may be risk factors for ventricular arrhythmias in uremic patients.