Accelerate Large-Scale Biomass Residue Utilization via Cofiring to Help China Achieve Its 2030 Carbon-Peaking Goals.

Cofiring biomass with coal for power generation is an affordable and ready-to-deploy technology to help reduce carbon emissions and resolve residual biomass. Cofiring has not been widely applied in China primarily because of some practical limitations, i.e., biomass accessibility, technological and economic constraints, and lack of policy support. We identified the benefits of cofiring with consideration of these practical limitations based on Integrated Assessment Models. We found that China produces 1.82 Bts/year of biomass residues, 45% of which is waste. 48% of the unused biomass can be utilized without fiscal intervention and 70% can be utilized with the subsidized Feed-in-Tariffs for biopower and carbon trading. The average Marginal Abatement Cost of cofiring is twice that of China's current carbon price. Cofiring can help China create 153 billion yuan of farmers' income annually and reduce 5.3 Bts of Committed Cumulative Carbon Emissions (CCCEs, 2023-2030), contributing to the needed CCCE mitigations to China's overall sector and the power sector by 32 and 86%, respectively. About 201 GW of coal-fired fleets are not compliant with China's 2030 carbon-peaking goals, and 127 GW can be saved by implementing cofiring, representing 9.6% of the total fleets in 2030.

TiO2/activated carbon synthesized by microwave-assisted heating for tetracycline photodegradation.

A furfural residue-derived activated carbon (AC) supported black-TiO2 photocatalyst was successfully prepared by ultrasonic-assisted sol-gel treatment (USG) and solvothermal treatment (ST) combined with microwave-assisted heating (MH). The prepared composites were characterized and evaluated based on the degradation of tetracycline hydrochloride (TC) under ultraviolet (UV) illumination. The average TiO2 nanoparticle size of the as-synthesized catalysts was between 9 and 11 nm. The bandgap of TiO2-USGM was 1.6 eV, much lower than that of other reference catalysts. Organic carbon and AC in the catalyst play positive roles in reducing the band gap (e.g. 1.6∼2.6 eV) and improving visible-light absorption. The oxygen vacancies are responsible for UV-visible absorption. Adding AC into black TiO2 resulted in a lower degree of recombination of photogenerated electrons. Mott-Schottky plots showed that AC-containing TiO2@AC-STM reduced the value of conduction band value from -0.59 eV to -0.24 eV, which is beneficial to photogenerated electrons. Compared with TiO2, the Ti-O-C and Ti-C- in TiO2@AC remarkably improved the adsorption and catalytic efficiency of TC. In a near-neutral pH environment, TiO2@AC-STM and TiO2@AC-USGM exhibited high removal efficiencies (88.0% and 75.7%, respectively) and degradation rates (0.0418 and 0.0302 µmol/g/s, respectively) at a catalyst load of 0.25 g/L. Notably, the catalyst can be effectively used over a wide range of pH (6-9). The solution pH after treatment was close to neutral, which is advantageous for wastewater treatment. The activation energies were found to be approximately 3.47 kJ/mol. The thermodynamic parameters showed that the photodegradation process was non-spontaneous and endothermic. Based on the trapping experiments, O2⋅- was mainly responsible for TC photodegradation over TiO2@AC-STM, followed by h+. The TC degradation pathways and catalyst stability were also investigated. Biomass-derived carbon-supported catalysts have great potential for waste biomass utilization as green, and low-cost catalysts.

Greenhouse Gas Emissions of Western Canadian Natural Gas: Proposed Emissions Tracking for Life Cycle Modeling.

Natural gas (NG) produced in Western Canada is a major and growing source of Canada's energy and greenhouse gas (GHG) emissions portfolio. Despite recent progress, there is still only limited understanding of the sources and drivers of Western Canadian greenhouse gas (GHG) emissions. We conduct a case study of a production facility based on Seven Generation Energy Ltd.'s Western Canadian operations and an upstream NG emissions intensity model. The case study upstream emissions intensity is estimated to be 3.1-4.0 gCO2e/MJ NG compared to current best estimates of British Columbia (BC) emissions intensities of 6.2-12 gCO2e/MJ NG and a US average estimate of 15 gCO2e/MJ. The analysis reveals that compared to US studies, public GHG emissions data for Western Canada is insufficient as current public data satisfies only 50% of typical LCA model inputs. Company provided data closes most of these gaps (∼80% of the model inputs). We recommend more detailed data collection and presentation of government reported data such as a breakdown of vented and fugitive methane emissions by source. We propose a data collection template to facilitate improved GHG emissions intensity estimates and insight about potential mitigation strategies.

Characterization and stabilization of incineration fly ash from a new multi-source hazardous waste co-disposal system: field-scale study on solidification and stabilization.

The multi-source hazardous waste co-disposal system, a recent innovation in the industry, offers an efficient approach for hazardous waste disposal. The incineration fly ash (HFA) produced by this system exhibits characteristics distinct from those of typical incineration fly ash, necessitating the use of adjusted disposal methods. This study examined the physicochemical properties, heavy metal content, heavy metal leaching concentration, and dioxin content of HFA generated by the new co-disposal system and compared them with those of conventional municipal waste incineration fly ash. This study investigated the solidification and stabilization of HFA disposal using the organic agent sodium diethyl dithiocarbamate combined with cement on a field scale. The findings revealed significant differences in the structure, composition, and dioxin content of HFA and FA; HFA contained substantially lower levels of dioxins than FA did. Concerning the heavy metal content and leaching; HFA exhibited an unusually high concentration of zinc, surpassing the permitted emission limits, making zinc content a critical consideration in HFA disposal. After stabilization and disposal, the heavy metal leaching and dioxin content of HFA can meet landfill disposal emission standards when a 1% concentration of 10% sodium diethyldithiocarbamate (DDTC) and 150% silicate cement were employed. These results offer valuable insights into the disposal of fly ash resulting from incineration of mixed hazardous waste.

Development of off-gas emission kinetics for stored wood pellets.

A lumped three-reaction kinetic model for off-gas emissions of stored wood pellets in sealed containers has been developed accounting for the formation of CO and CO(2) and the depletion of O(2). Off-gas emission data at different conditions were used to extract kinetic model parameters by numerically fitting the proposed model equations. The fitted kinetic model parameters for different cases showed consistency with one another. With properly estimated model parameters, the current kinetic model can be used to predict off-gas emissions, oxygen depletion, and the buildup of toxic air pollutants in wood pellet storage containers/vessels.

Shoutai pills for threatened abortion: A protocol for systematic review and meta-analysis.

BACKGROUND: Threatened abortions are a serious health risk for women. Deferiprone tablets are commonly used in the treatment of clinical delivery. Traditional Chinese medicine, a characteristic medical system inherited for thousands of years, often applies Shoutai pills in the treatment of Threatened abortion and has achieved good results. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of Shoutai pills combined with dedrogesterone tablets for the treatment of early preterm abortion. METHODS: Electronic searches of clinical randomized controlled trials in PubMed, Web of Science, MEDLINE, EMBASE, China National Knowledge Infrastructure, Wanfang database, and China Scientific Journal Database (VIP) were conducted. References to the included literature, gray literature in Open Grey, and other relevant literature such as clinical studies registered in ClinicalTrials.gov, were also manually searched. Relevant data were extracted, and a meta-analysis was performed using Reviewer Manager 5.4. RESULTS: The results of this study will be submitted to peer-reviewed journals. CONCLUSION: This study provides high-quality evidence on the efficacy and safety of Shoutai pills in combination with dedrogesterone tablets for the treatment of preterm abortion.

Emerging applications of biochar: A review on techno-environmental-economic aspects.

Biomass fast pyrolysis produces bio-oil and biochar achieving circular economy. This review explored the emerging applications of biochar. Biochar possesses the unique properties for removing emerging contaminants and for mine remediation, owing to its negative charge surface, high specific surface area, large pore size distribution and surface functional groups. Additionally, biochar could adsorb impurities such as CO2, moisture, and H2S to upgrade the biogas. Customizing pyrolysis treatments, optimizing the feedstock and pyrolysis operating conditions enhance biochar production and improve its surface properties for the emerging applications. Life cycle assessment and techno-economic assessment indicated the benefits of replacing conventional activated carbon with biochar.

Radial distribution modeling of liquid-phase phenol concentration in a liquid-solid fluidized bed photoreactor.

A fluidized bed photoreactor with titanium dioxide-immobilized spherical activated carbon particles was examined. The light intensity profile was modeled using the Lambert-Beer rule for the modeling of the radial distribution of liquid-phase phenol concentration in the fluidized bed photoreactor, when considering the reactor composed of numerous differential annular drums and no mass transfer between drums. The model could be well matched with the experimental data which indicated the liquid flow rate of 13.8 L/min was the optimum in the balance of flow rate-related light penetration and photocatalyst concentration. By integration of liquid-phase phenol concentration along the radius, photocatalytic oxidation performance of the photoreactor was evaluated in comparison with the experimental data and model prediction. The results showed that the errors were less than 30% for most of the predictions. It is suggested that mass transfer and flow rate difference along the radial direction should be considered to obtain more precise prediction.

Valorization of fluid petroleum coke for efficient catalytic destruction of biomass gasification tar.

Large volumes of waste petroleum coke stockpiled in open yard not only represent a huge loss of valuable material but also pose a significant risk to the environment. This work proposed an innovative strategy for waste petroleum coke valorization by exploring its catalytic performance of biomass gasification tar destruction. Waste petroleum coke was firstly activated by potassium hydroxide (KOH) to obtain high specific surface area as well as low sulfur and ash contents. Petroleum coke derived catalyst showed superior performance than a commercial activated carbon derived catalyst for destruction of naphthalene as the tar model compound. The petroleum coke derived catalyst exhibited 99.1% naphthalene destruction efficiency at 800 °C but deactivated quickly under N2 atmosphere. Under H2 and steam atmospheres, the catalytic activities were 98.6% and 96.5% for 8 h, respectively. To study the correlation between catalytic performance and the structure of carbon catalyst, elemental analysis, scanning electron microscope (SEM) analysis, transmission electron microscope (TEM) analysis, X-ray powder diffraction (XRD) analysis, Brunauer-Emmett-Teller method (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, temperature programmed oxidation (TPO) analysis and Raman spectroscopy were performed on both fresh and spent catalysts. Results demonstrated that the hydrogen-rich groups (small rings and amorphous carbon) and oxygen-containing groups may account for the good resistance to coke deposition under H2 and steam atmospheres.

Co-pyrolysis of biomass and polyvinyl chloride under microwave irradiation: Distribution of chlorine.

Co-pyrolysis of sophora wood (SW) and polyvinyl chloride (PVC) was conducted in a microwave reactor at different temperatures and different mixing ratios, and the transformation and distribution of chlorine in pyrolysis products were investigated. Microwave pyrolysis is a simple and efficient technique with better heating uniformity and process controllability than conventional heating. Compared with PVC pyrolysis, the addition of SW significantly reduced CO2 yield and greatly increased the yield of CO. The yield and quality of pyrolysis oil were effectively improved by SW, and the content of chlorine-containing compounds in the oil was suppressed to <1% at low temperatures (<550 °C). Co-pyrolysis of SW and PVC reduced the chlorine emissions from 59.07% to 28.09% and promoted the retention of chlorine in char (from 0.33% to 4.72%). Cellulose, hemicellulose, and lignin were co-pyrolyzed with PVC to investigate their effects on chlorine distribution. The experiments demonstrated that lignin had the most significant effects on reducing gas phase chlorine emission and achieving chlorine immobilization, and chlorine mainly existed in the form of sodium chloride in the char of lignin-PVC co-pyrolysis. Hence co-pyrolysis of lignocellulosic biomass and PVC provides a practical pathway for utilization of PVC waste in an environmentally friendly manner, realizing efficient chlorine retention and significantly reducing chlorine-related emissions.

Simulation of heavy metals behaviour during Co-processing of fly ash from municipal solid waste incineration with cement raw meal in a rotary kiln.

Fly ash produced from incineration of municipal solid wastes (MSW) contains heavy metals, such as Cd and Pb, that make this material difficult to manage and dispose of safely. Because the composition of fly ash is similar to cement raw meal, partial replacement of raw meal with fly ash may be a feasible way to reduce the health and environmental hazards of the ash, provided that the heavy metals can be effectively stabilized in the solid phase. This research employs proprietary thermochemical software to simulate the thermodynamic behavior and single-step fixation of Cd and Pb in industrial cement kilns. The effect of Cd, Pb and Cl loadings on the fixation and/or evaporation of Cd and Pb during the sintering process is analyzed using data from industrial cement kilns. A simplified model is created based on elemental mass balance to evaluate multi-step fixation of Cd and Pb with cement kiln dust recycle.The results indicate that Cd forms Cd(OH)2(g) in a highly alkaline environment, while nearly 90% Pb is volatilized as PbCl2(g). In the clinker, increased Cl-1 decreased the proportion of Pb and Cd, moreover, Pb and Cd increased in kiln dust with Cl-1 increased; Calculations using a kiln dust recycle model showed that, the concentrations of Pb and Cd in both kiln dust and clinker increased sharply after recycling of kiln dust in steady state. Under unstable conditions, the concentrations of Pb and Cd in kiln dust increased, as well as the heavy metals re-entering the cement kiln.

A case study on integrating anaerobic digestion into agricultural activities in British Columbia: Environmental, economic and policy analysis.

This paper provides an example of the kind of analysis needed to support better targeted policies to reduce the environmental impacts of agricultural activities, using the specific case of Anaerobic Digestion (AD) to treat animal manure and other agricultural and food wastes in British Columbia (BC). Economic and life cycle environmental performance metrics are estimated to compare integrated and stand-alone systems using the resulting biogas and digestate. Using biogas for heating outperforms purifying it for distribution as renewable natural gas (RNG). However, current policy and energy prices in BC perversely support RNG, making biogas-fired heating systems economically unattractive. The performance of biogas-fired heating system can be improved and their dependence on subsidies reduced by integration with local agricultural activities, exploiting CO2 and digestate as by-products. Biogenic CO2, from combustion of the biogas and from mushroom cultivation, can displace natural gas use in producing CO2-enriched atmospheres to enhance growth rates in greenhouse production. Using digestate as growing media in greenhouses and mushroom cultivation can generate significant revenues but the environmental benefits are nugatory. Co-digestion of food waste can further improve performance by increasing biogas yield. With all extra benefits combined, integrated AD systems can increase both GHG mitigation and revenues by at least 80%. The analysis illustrates the general point that, to avoid perverse outcomes, policy measures must support options based on their actual GHG mitigation benefits, rather than targetting any specific technology.

Effects of phosphorous precursors and speciation on reducing bioavailability of heavy metal in paddy soil by engineered biochars.

Ammonium phosphate (AP), phosphoric acid (PC), and potassium phosphate (TKP) were used for the modification of biochar for enhanced heavy metal passivation in soil. The effect of various phosphorus (P) precursors on adsorption-related properties, P speciation distribution pattern, and the passivation mechanism was investigated by BET, FTIR, XRD, XPS, and 31P NMR analysis. The mobility and bio-availability of cadmium (Cd) were studied by extraction experiments, and the P release kinetics was also determined. Results showed that the immobilization efficiency of Cd (II) by biochars followed the order: TKP-BC > PC-BC > AP-BC > BC, and TKP-BC reduced available Cd content by 81% treated with 2% addition. The P speciation shows a significant effect on the P-enriched biochars' passivation performance, especially orthophosphate, which is essential for the immobilization of Cd2+ by forming phosphate precipitation. Pyrophosphate and orthophosphate monoester in AP-BC and PC-BC can promote Cd2+ passivation via the formation of P-Cd complexes or organometallic chelates. It is also shown that PC-BC has the lowest P release rate while TKP-BC has the highest percentage of P (15.50%) remaining in the biochar. The results may contribute to the development of modified biochar for soil remediation based on P-related technologies.

Engineered biochars from catalytic microwave pyrolysis for reducing heavy metals phytotoxicity and increasing plant growth.

Pb, Ni, and Co are among the most toxic heavy metals that pose direct risks to humans and biota. There are no published studies on biochars produced at low temperatures (i.e., 300 °C), which possess high sorption capacity for heavy metal remediation and reclamation of contaminated sandy soils. This research studied the effect of catalytic microwave pyrolysis of switchgrass (SG) using bentonite and K3PO4 to produce biochar at low temperature (300 °C) with high sorption capacity for reducing the phytotoxicity of heavy metals, and investigated the synergistic effects of catalyst mixture on biochar sorption capacity. The quality of the biochars was examined in terms of their impacts on plant growth, reducing phytotoxicity and uptake of heavy metals in sandy soil spiked with Pb, Ni, and Co. All catalysts increased the micropore surface area and cation-exchange capacity of biochars, and resulted in biochars rich in plant nutrients, which not only decreased heavy metal phytotoxicity, but also boosted plant growth in the spiked soil by up to 140% compared to the sample without biochar. By mixing bentonite and K3PO4 with SG during microwave pyrolysis, the efficacy of biochar in reducing phytotoxicity and heavy metals uptake was further enhanced because of the highest micropore surface area (402 m2/g), moderate contents of Ca, Mg, K, and Fe for ion-exchange and moderate concentration of phosphorus for the formation of insoluble heavy metal compounds. Generally, the biochar created at 300 °C (300-30KP) showed similar performance to the biochar created at 400 °C (400-30KP) in terms of reducing heavy metal bioavailability.

Microwave pyrolysis of oily sludge under different control modes.

The effects of temperature and power on product distribution and characteristics of oily sludge (OS) pyrolysis were investigated in a microwave reactor. The maximum oil yield was 72.55 wt% at 550 °C and 71.47 wt% at 800 W, respectively. X-ray photoelectron spectroscopy (XPS) indicated that C-C and C-O were the main forms of carbon in OS char (OC). The sulfur (S) content in OC increased as the temperature/power rose, implying that S might exist in the form of inorganics or OC had S retention ability. In temperature control mode, the changes of functional groups on OC surface were more sensitive. The maximum hydrocarbon content in oil was 14.56% at 350 °C and 13.40% at 900 W, respectively. The contents of oxygenated compounds and heterocycles in oil from temperature control mode were higher. The CO yield increased with increasing temperature/power, reaching the maximum of 9.60 wt% at 650 °C and 7.75 wt% at 900 W, respectively. Compared with power control mode, it seemed that more heavy metals (HMs) were retained in OC in temperature control mode. The Er of HMs were at the clean level and RI indicated the HMs in OC had a low environmental risk.

Modeling of off-gas emissions from wood pellets during marine transportation.

After a fatal accident during the discharge of wood pellets at Helsingborg, emissions from pellets during marine transportation became a concern for the safe handling and storage of wood pellets. In this paper, a two-compartment model has been developed for the first time to predict the concentrations of CO, CO2, CH4, and O2 inside the cargo ship and the time and rate of forced ventilation required before the safe entry into the stairway adjacent to the storage hatch. The hatch and stairway are treated as two perfectly mixed tanks. The gas exchange rate between these two rooms and the gas exchange rate with the atmosphere are fitted to satisfy a measured tracer final concentration of 33 p.p.m.v. in the stairway and an average final hatch to stairway CO, CO2, and CH4 concentration ratio of 1.62 based on measurement from five other hatch and stairway systems. The reaction kinetics obtained from a laboratory unit using a different batch of pellets, however, need to be scaled in order to bring the prediction to close agreement with onboard measured emission data at the end of voyage. Using the adjusted kinetic data, the model was able to predict the general trend of data recorded in the first 12.5 days of the voyage. Further validation, however, requires the data recorded over the whole journey. The model was applied to predict the effect of ocean temperature on the off-gas emissions and the buildup of concentrations in the hatch and stairway. For safe entry to the cargo ship, the current model predicted that a minimal ventilation rate of 4.4 hr⁻¹ is required for the stairway's CO concentration to lower to a safe concentration of 25 p.p.m.v. At 4.4 hr⁻¹, 10 min of ventilation time is required for the safe entry into the stairway studied.

Synergistic Effects of Catalyst Mixtures on Biomass Catalytic Pyrolysis.

This paper studied the synergistic effects of catalyst mixtures on biomass catalytic pyrolysis in comparison with the single catalyst in a microwave reactor and a TGA. In general, positive synergistic effects were identified based on increased mass loss rate, reduced activation energy, and improved bio-oil quality compared to the case with a single catalyst at higher catalyst loads. 10KP/10Bento (a mixture of 10% K3PO4 and 10% bentonite) increased the mass loss rate by 85 and 45% at heating rates of 100 and 25°C/min, respectively, compared to switchgrass without catalyst. The activation energy for 10KP/10Bento and 10KP/10Clino (a mixture of 10% K3PO4 and 10% clinoptilolite) was slightly lower or similar to other catalysts at 30 wt.% load. The reduction in the activation energy by the catalyst mixture was higher at 100°C/min than 25°C/min due to the improved catalytic activity at higher heating rates. Synergistic effects are also reflected in the improved properties of bio-oil, as acids, aldehydes, and anhydrosugars were significantly decreased, whereas phenol and aromatic compounds were substantially increased. 30KP (30% K3PO4) and 10KP/10Bento increased the content of alkylated phenols by 341 and 207%, respectively, in comparison with switchgrass without catalyst. Finally, the use of catalyst mixtures improved the catalytic performance markedly, which shows the potential to reduce the production cost of bio-oil and biochar from microwave catalytic pyrolysis.

Rate and peak concentrations of off-gas emissions in stored wood pellets--sensitivities to temperature, relative humidity, and headspace volume.

Wood pellets emit CO, CO(2), CH(4), and other volatiles during storage. Increased concentration of these gases in a sealed storage causes depletion of concentration of oxygen. The storage environment becomes toxic to those who operate in and around these storages. The objective of this study was to investigate the effects of temperature, moisture, and the relative size of storage headspace on emissions from wood pellets in an enclosed space. Twelve 10-l plastic containers were used to study the effects of headspace ratio (25, 50, and 75% of container volume) and temperatures (10-50 degrees C). Another eight containers were set in uncontrolled storage relative humidity (RH) and temperature. Concentrations of CO(2), CO, and CH(4) were measured by gas chromatography (GC). The results showed that emissions of CO(2), CO, and CH(4) from stored wood pellets are more sensitive to storage temperature than to RH and the relative volume of headspace. Higher peak emission factors are associated with higher temperatures. Increased headspace volume ratio increases peak off-gas emissions because of the availability of oxygen associated with pellet decomposition. Increased RH in the enclosed container increases the rate of off-gas emissions of CO(2), CO, and CH(4) and oxygen depletion.

Effects of headspace and oxygen level on off-gas emissions from wood pellets in storage.

Few papers have been published in the open literature on the emissions from biomass fuels, including wood pellets, during the storage and transportation and their potential health impacts. The purpose of this study is to provide data on the concentrations, emission factors, and emission rate factors of CO(2), CO, and CH(4) from wood pellets stored with different headspace to container volume ratios with different initial oxygen levels, in order to develop methods to reduce the toxic off-gas emissions and accumulation in storage spaces. Metal containers (45 l, 305 mm diameter by 610 mm long) were used to study the effect of headspace and oxygen levels on the off-gas emissions from wood pellets. Concentrations of CO(2), CO, and CH(4) in the headspace were measured using a gas chromatograph as a function of storage time. The results showed that the ratio of the headspace ratios and initial oxygen levels in the storage space significantly affected the off-gas emissions from wood pellets stored in a sealed container. Higher peak emission factors and higher emission rates are associated with higher headspace ratios. Lower emissions of CO(2) and CO were generated at room temperature under lower oxygen levels, whereas CH(4) emission is insensitive to the oxygen level. Replacing oxygen with inert gases in the storage space is thus a potentially effective method to reduce the biomass degradation and toxic off-gas emissions. The proper ventilation of the storage space can also be used to maintain a high oxygen level and low concentrations of toxic off-gassing compounds in the storage space, which is especially useful during the loading and unloading operations to control the hazards associated with the storage and transportation of wood pellets.