Annual Greenhouse Gas Research Articles

Effects of straw returning combined with blended controlled-release urea fertilizer on crop yields, greenhouse gas emissions, and net ecosystem economic benefits: A nine-year field trial

Although straw returning combined with blended controlled-release urea fertilizer (BUFS) has been shown to improve wheat-maize rotation system productivity, their effects on greenhouse gas (GHG) emissions, carbon footprints (CF), and net ecosystem economic benefits (NEEB) are still unknown. Life cycle assessment was used to investigate a long-term (2013–2022) wheat-maize rotation experiment that included straw combined with two N fertilizer types [BUFS and (conventional urea fertilizer) CUFS] and straw-free treatments (BUF and CUF). The results showed that BUFS and CUFS treatments increased the annual yield by 13.8% and 11.5%, respectively, compared to BUF and CUF treatments. The BUFS treatment increased the yearly yield by 13.8% compared to the CUFS treatment. Since BUFS and CUFS treatments increased soil organic carbon (SOC) sink sequestration by 25.0% and 27.0% compared to BUF and CUF treatments, they reduced annual GHG emissions by 7.1% and 4.7% and CF per unit of yield (CFY) by 13.7% and 9.6%, respectively. BUFS treatment also increased SOC sink sequestration by 20.3%, reduced GHG emissions by 10.7% and CFY by 23.0% compared to CUFS treatment. It is worth noting that the BUFS and CUFS treatments increased the annual ecological costs by 41.6%, 26.9%, and health costs by 70.1% and 46.7% compared to the BUF and CUF treatments, but also increased the net yield benefits by 9.8%, 6.8%, and the soil nutrient cycling values by 29.2%, 27.3%, and finally improved the NEEB by 10.1%, 7.3%, respectively. Similar results were obtained for the BUFS treatment compared to the CUFS treatment, ultimately improving the NEEB by 23.1%. Based on assessing yield, GHG emissions, CF, and NEEB indicators, the BUFS treatment is recommended as an ideal agricultural fertilization model to promote sustainable and clean production in the wheat-maize rotation system and to protect the agroecological environment.

Aging Increases Global Annual Food Greenhouse Gas Emissions up to 300 Million Tonnes by 2100.

The dietary preferences of the elderly population exhibit distinct variations from the overall averages in most countries, gaining increasing significance due to aging demographics worldwide. These dietary preferences play a crucial role in shaping global food systems, which will result in changed environmental impacts in the future such as greenhouse gas (GHG) emissions. We present a quantitative evaluation of the influence of population aging on the changes in GHG emissions from global food systems. To achieve this, we developed regional dietary coefficients (DCs) of the elderly based on the Global Dietary Database (GDD). We then reconciled the GDD with the dataset from the Food and Agriculture Organization of the United Nations (FAO) to calculate the food GHG emissions of the average population in each of the countries. By applying the DCs, we estimated the national food GHG emissions and obtained the variations between the emissions from aged and average populations. We employed a modified version of the regional integrated model of climate and the economy model (RICE) to forecast the emission trends in different countries based on FAO and GDD data. This integrated approach allowed us to evaluate the dynamic relationships among aging demographics, food consumption patterns, and economic developments within regions. Our results indicate that the annual aging-embodied global food GHG emissions will reach 288 million tonnes of CO2 equivalent (Mt CO2e) by 2100. This estimation is crucial for policymakers, entrepreneurs, and researchers as it provides insights into a potential future environmental challenge and emphasizes the importance of sustainable food production and consumption strategies to GHG emission mitigations associated with aging dietary patterns.

From sink to source: Dynamic of greenhouse gases emissions from beach wrack accumulations in a temperate coastal bay

Coastal ecosystems such as salt marshes, seagrass meadows, and kelp forests contribute to climate regulation as carbon sinks. However, coastal ecosystems may act as carbon sources as beach wrack accumulations may release greenhouse gases (GHG) during decomposition. The magnitude of GHG emissions of beach wrack accumulations under natural conditions are poorly understood, hampering accurate blue carbon accountings. In this study, we assessed the spatio-temporal variability and environmental factors driving CO2, CH4 and N2O emissions from beach wrack accumulations on a temperate sandy beach. Beach wrack accumulations, dominated by Zostera marina and opportunistic brown macroalgae, presented variable spatio-temporal dynamics. Annual beach wrack GHG emissions achieved up to 77,915 mg m−2 d−1 CO2e (CO2 equivalents) and varied largely throughout the study period due to interactive effects of temperature, wave exposure, beach wrack biomass moisture, abundance, and species composition. Our findings showed that methane emissions in new, freshly deposited, and in drifting wrack in the water reached up to 100 mg m−2 d−1, representing up to 57 % of annual CO2e emissions occurring throughout the year. Nitrous oxide emissions were highly variable and comprised a minor extent (i.e., up to 4 %) of annual CO2e emissions. Together, wrack CH4 and N2O emissions provided 13.69 g CO2 m−2 per year to the atmosphere. Our findings indicate that excessive opportunistic macroalgae biomass driven by eutrophication may explain increased CO2 and N2O emissions. We conclude that whilst beach wrack depositions are a natural and essential part of coastal ecosystems, they may provide an extra source of GHG to the atmosphere, potentially counteracting the role of vegetated coastal ecosystems as carbon sinks.

Greenhouse Gas Emissions Inventory from Roadway Construction: Case Study for the Washington State Department of Transportation

Recent emphasis on actions to reduce greenhouse gas (GHG) emissions has pushed many state departments of transportation (DOTs) to develop carbon accounting practices compatible with their current standard data collection and storage guidelines. Once accurate and reliable accounting of GHG emissions is established, strategies can be formed that could help mitigate the adverse environmental impacts of materials used by state DOTs. To date, the Washington State Department of Transportation (WSDOT) has not conducted comprehensive research on the embodied carbon within its construction material usage (i.e., upstream Scope 3 emissions inventory of procured materials) with most previous carbon accounting practices being focused on Scope 1 and Scope 2 emissions (i.e., the carbon footprint of direct and indirect energy usage). This paper summarizes the results of a life cycle assessment on the agency-wide material procurements and construction operations that emit GHGs at WSDOT as a case study. This study uses several data sources from WSDOT in conjunction with publicly available life cycle emissions factor data to estimate GHG emissions attributed to the materials used to build and maintain roadways under WSDOT’s jurisdiction. Results indicate that upstream Scope 3 emissions for WSDOT as an agency is a significant contributor to its overall GHG emissions inventory. Specifically, between 2017 and 2022, this paper estimates an average annual upstream Scope 3 emissions of 310,000 metric tons of CO2 equivalents, which translates to 56% of the total annual GHG emissions including Scope 1 and 2 emissions.

Multi-dimensional low-carbon assessments of wind-driven seawater desalination system via hybrid life cycle modeling

Wind-driven desalination is a representative technology of renewable energy that not only alleviates water shortages but also reduces greenhouse gas (GHG) emissions generated by the utilization of fossil fuels. This study examined the GHG emissions from a wind-driven seawater desalination system by using the hybrid input-output life-cycle analysis (IO-LCA) to undertake a comprehensive low-carbon assessment by comparing with traditional thermal seawater desalination systems over the whole life cycle. The findings indicate that the GHG emissions of the wind-driven seawater desalination system are 96.14% lower than those of the traditional system. According to estimations, if reverse osmosis (RO) desalination is driven by wind power technologies at a larger scale, the annual GHG emissions can be reduced by an amount between 7.54E+05 and 3.71E+06 t CO2-eq. Although the construction stage increases the emissions to 55.41% over the whole life cycle, the payback period (Ypp) is about 2.69 years, which means that the level of GHG emissions could be reduced by 25.42% of the level of the traditional systems. Based on the multi-dimensional low-carbon assessment, this study is expected to provide quantitative assessments and policy implications to integrate low-carbon technologies with seawater desalination and promote sustainable development of seawater desalination industries.

Greenhouse gas emissions benefits of the lightweight vehicle fleet in China: A dynamic fleet perspective

Lightweighting is believed to be a silver bullet to reduce greenhouse gas (GHG) emissions related to the road transportation. However, the fleet-scale and long-term GHG emissions estimation on the light-duty passenger vehicle (LDPV) fleet in China is still underexplored. A dynamic fleet-based life cycle assessment (LCA) model is developed to predict the annual GHG emissions attributable to the lightweight LDPV fleet in China at provincial level. With the most aggressive implementation of lightweighting, the cumulative mitigation potential of lightweight LDPV fleet from 2021 to 2050 is 0.72 Gt CO2 eq and 0.55 Gt CO2 eq using high-strength steel (AHSS) and aluminium (Al), respectively. Sooner implementation brings a higher cumulative reduction in GHG emissions. Delaying the implementation by five years would sacrifice 0.16 Gt CO2 eq ∼0.2 Gt CO2 eq cumulative reduction, and the loss would increase to 0.31 Gt CO2 eq ∼0.41 Gt CO2 eq when postpone the lightweighting by ten years.

Rainstorm and strong wind weathers largely increase greenhouse gases flux in shallow ponds

Shallow-water ponds represent the hotspots of greenhouse gas (GHG) emissions. Most current studies focus on the temporal dynamics for GHGs in water, with little consideration given to the effects of weather changes. In this study, we measured and compared the concentrations and fluxes of CO2, CH4, and N2O from a pond in Northeast China under different meteorological conditions. Results showed that the rates of CO2, CH4, and N2O emissions from pond into the atmosphere during strong winds were 85.85 ± 7.55 mmol m−2 d−1, 22.05 ± 6.80 mmol m−2 d−1, and 10.87 ± 0.72 μmol m−2 d−1, respectively, significantly higher than those measured during non-rain weather. Among which, over 88 % of CH4 emissions were contributed by ebullition. Meanwhile, the CO2 and N2O flux were also significantly higher during heavy rainfall, reaching 100.05 ± 19.76 mmol m−2 d−1 and 5.90 ± 1.03 μmol m−2 d−1, respectively. Strong winds and precipitation induced sediment disturbances, high gas transport coefficients, reduced photosynthesis and oxygen greatly promoted the GHGs escape evasion. Wind speed, air pressure, solar radiation, and dissolved oxygen in water were important influencing factors. Our results emphasize the importance of capturing short-term weather disturbance events, especially rainstorm and strong winds, to accurately assess the annual GHG budget from these shallow water ecosystems.

Evaluation of solid-liquid separation of dairy manure with different separator screen sizes on the resource recovery and greenhouse gas emissions reduction

Solid-liquid separation is a critical step for the treatment of dairy manure, and the separator screen size plays an important role in determining the separation. Despite its importance, the impact of screen size on subsequent resource recovery and greenhouse gas (GHG) emissions reduction remains largely undetermined and varied. In this study, the influence of separator screen size for solid-liquid separation on resources recovery (bedding materials, biogas and nutrients) and GHG emissions reduction was evaluated. Taking a dairy farm with a stock of 1000 cows as an example, with the increasing of separator screen size from 0.5 mm to 5 mm, the results show that the annual bedding materials production decreased from 987.0 tons to 597.6 tons (dry basis), the annual biogas production increased from 32.5 × 104 m³ to 50.9 × 104 m³, the annual total nitrogen (TN) recovery increased from 35.8 tons to 44.4 tons, and the annual total phosphorus (TP) recovery increased from 8.2 tons to 10.1 tons. The annual economic benefits from resource recovery ranged from 28.7 × 104 ¥ to 34.8 × 104 ¥. Annual total GHG emissions increased with the increasing separator screen size and reached approximately 0.7 t CO2 equivalent/cow·year. These findings provide guidance for the selection of separator screen size for the solid-liquid separation of dairy manure.

Sustainable solar energy development in Zakho, Iraq: a techno-economic and environmental assessment

This study presents a solar energy roadmap aimed at attracting investors to capitalize on the abundant solar resources in Zakho, Iraq, for clean energy technology. The objective is to mitigate global warming effects caused by fossil fuel combustion and promote sustainable technological development. To end this, the study employs RETScreen Expert software to validate the techno-economic and environmental viability of a grid-connected solar photovoltaic system utilizing climatic data from the Astronaut Office Information System (NASA) Database. Additionally, the Photovoltaic Geographical Information System (PVGIS) modeling method determines optimal angles for installing residential rooftop Photovoltaic (PV) systems across selected locations. Results indicate that all selected locations are suitable for solar photovoltaic projects, with Rezgari identified as the optimal district due to its highest annual solar radiation of 1863.117 kWh/m2 and the highest annual electricity production at 7905.38 kWh. The capacity factor (CF) values fall within the range of 17.395-17.574%. The study reveals an annual greenhouse gas (GHG) emissions reduction ranging from 6.9876 to 7.1123 (tCO2) across four districts. Considering the financial and environmental indicators, Rooftop Photovoltaic Systems emerge as a sustainable and efficient solution to enhance the environment and prove economically viable in Zakho City.

Carbon footprint of hospital laundry: a life-cycle assessment

ObjectivesTo assess greenhouse gas (GHG) emissions from a regional hospital laundry unit, and model ways in which these can be reduced.DesignA cradle to grave process-based attributional life-cycle assessment.SettingA large hospital...

Transition to cellular agriculture reduces agriculture land use and greenhouse gas emissions but increases demand for critical materials

Cellular agriculture, that is, the production of cultured meat and microbial proteins, has been developed to provide food security for a growing world population. The use of green energy technologies is recommended to ensure the sustainability of changing traditional agriculture to a cellular one. Here, we use a global dynamic model and life-cycle assessment to analyze scenarios of replacing traditional livestock products with cellular agriculture from 2020 to 2050. Our findings indicate that a transition to cellular agriculture by 2050 could reduce annual greenhouse gas emissions by 52%, compared to current agriculture emissions, reduce demand for phosphorus by 53%, and use 83% less land than traditional agriculture. A maximum 72% replacement of livestock products with cellular agriculture using renewable energy is possible based on the 2050 regional green energy capacities. A complete transition can be achieved but requires 33% of the global green energy capacities in 2050. Further, the accelerated demand for critical materials will not exceed their primary production capacities, except for tellurium. We conclude that a transition to cellular agriculture is possible with environmental benefits and provide a benchmark to study different alternatives to animal-based diets.

Large contribution of soil N2O emission to the global warming potential of a large-scale oil palm plantation despite changing from conventional to reduced management practices

Abstract. Conventional management of oil palm plantations, involving high fertilization rate and herbicide application, results in high yield but with large soil greenhouse gas (GHG) emissions. This study aimed to assess a practical alternative to conventional management, namely reduced fertilization with mechanical weeding, to decrease soil GHG emissions without sacrificing production. We established a full factorial experiment with two fertilization rates (conventional and reduced fertilization, equal to nutrients exported via fruit harvest) and two weeding methods (herbicide and mechanical), each with four replicate plots, since 2016 in a ≥ 15-year-old, large-scale oil palm plantation in Indonesia. Soil CO2, N2O, and CH4 fluxes were measured during 2019–2020, and yield was measured during 2017–2020. Fresh fruit yield (30 ± 1 Mgha-1yr-1) and soil GHG fluxes did not differ among treatments (P≥ 0.11), implying legacy effects of over a decade of conventional management prior to the start of the experiment. Annual soil GHG fluxes were 5.5 ± 0.2 Mg CO2-C ha−1 yr−1, 3.6 ± 0.7 kg N2O-N ha−1 yr−1, and −1.5 ± 0.1 kg CH4-C ha−1 yr−1 across treatments. The palm circle, where fertilizers are commonly applied, covered 18 % of the plantation area but accounted for 79 % of soil N2O emission. The net primary production of this oil palm plantation was 17 150 ± 260 kgCha-1yr-1, but 62 % of this was removed by fruit harvest. The global warming potential of this planation was 3010 ± 750 kgCO2eqha-1yr-1, of which 55 % was contributed by soil N2O emission and only < 2 % offset by the soil CH4 sink.

A restatement of the natural science evidence base concerning grassland management, grazing livestock and soil carbon storage.

Approximately a third of all annual greenhouse gas emissions globally are directly or indirectly associated with the food system, and over a half of these are linked to livestock production. In temperate oceanic regions, such as the UK, most meat and dairy is produced in extensive systems based on pasture. There is much interest in the extent to which such grassland may be able to sequester and store more carbon to partially or completely mitigate other greenhouse gas emissions in the system. However, answering this question is difficult due to context-specificity and a complex and sometimes inconsistent evidence base. This paper describes a project that set out to summarize the natural science evidence base relevant to grassland management, grazing livestock and soil carbon storage potential in as policy-neutral terms as possible. It is based on expert appraisal of a systematically assembled evidence base, followed by a wide stakeholders engagement. A series of evidence statements (in the appendix of this paper) are listed and categorized according to the nature of the underlying information, and an annotated bibliography is provided in the electronic supplementary material.

Energy, economic, and environmental analysis: A study of operational strategies for combined heat and power system based on PEM fuel cell in the East China region

This study introduces a combined heat and power (CHP) system primarily based on proton exchange membrane (PEM) fuel cells, which can provide electricity and heat for residential buildings in the East China region under two operating strategies. The analysis and discussion focus on the impact of parameters such as current density and gas inlet pressure on the system's output power and efficiency. The results indicate that excessively high current density decreases the system's electricity generation efficiency, while a moderate increase in hydrogen inlet pressure contributes to greater heat generation. Considering energy, economic, and environmental factors, the system operates with the thermal-led strategy in parallel with the grid, resulting in a substantial 73.3 % reduction in fuel costs. The annual greenhouse gas (GHG) emissions and the amount of emission reduction are lowered to 6.96 × 107 g and 3.39 × 107 g, respectively.

High organic carbon content constricts the potential for stable organic carbon accrual in mineral agricultural soils in Finland

Sequestering carbon into agricultural soils is considered as a means of mitigating climate change. We used agronomic soil test results representing c. 95% of the farmed land area in Finland to estimate the potential of the uppermost 15 cm soil layer of mineral agricultural soils to sequester organic carbon (OC) and to contribute to the mitigation of climate change. The estimation of the maximum capacity of mineral matter to protect OC in stable mineral-associated form was based on the theory that clay and fine-sized (fines = clay + silt) particles have a limited capacity to protect OC. In addition, we used the clay/OC and fines/OC ratios to identify areas with a risk of erosion and reduced productivity, thus indicating priority areas potentially benefitting from the increased soil OC contents. We found that 32–40% of the mineral agricultural soils in Finland have the potential to further accumulate mineral-associated OC (MOC), while in the majority of soils, the current OC stock in the uppermost 15 cm exceeded the capacity of mineral matter to protect OC. The nationwide soil OC sequestration potential of the uppermost 15 cm in mineral agricultural soils ranged between 5 and 10 Tg, which corresponds to less than the annual greenhouse gas emissions in Finland. The fields with the highest potential for SOC accrual were found in the southern and southwestern parts of the country, including some of the most intensively cultivated high-clay soils. Although the nationwide potential for additional OC sequestration was estimated to be relatively small, the current OC storage in Finnish arable mineral soils (0-15 cm) is large, 128 Tg. Farming practices enabling maximum OC input into the soil play an important role as a tool for mitigating the loss of carbon from high-OC soils in the changing climate. Furthermore, especially in high-clay areas with potential for MOC accrual, efforts to increase soil OC could help improve soil structural stability and therefore reduce erosion and the loss of nutrients to the aquatic environments.

Heat Pump as an Emission Reduction Measure for Ships

Greenhouse gas regulations from the International Maritime Organization, such as the Carbon Intensity Indicator and the Energy Efficiency Existing Ship Index are drawing attention to the implementation of energy efficiency technologies in ships to lower emissions. Presently, more attention is paid to energy efficiency measures related to propulsion (e.g. speed management) and auxiliary energy use (e.g. onshore power). This study compares the environmental impact and cost of replacing heat pumps as an energy efficiency measure instead of oil-fired boilers for two case study vessels by comparing the life cycle impact of different strategies to fulfill the thermal load of vessels while at the port. In terms of life cycle emissions, the heat pump operated using onshore power has the potential to reduce global warming potential by 88% compared to an oil-fired boiler. This accounts for saving 3% and 8% of annual greenhouse gas emissions from entire ship operations, including emissions from engines for the respective case study ships. In addition, shifting to a heat pump avoids NOx and SOx emissions, which adversely affect air quality in the populated areas near the port. Cost results show that the heat pump has an overall higher cost of ownership for case study vessel 1 and a lower cost of ownership for case study vessel 2 compared to oil-fired boiler. Depending on the energy use of specific ships, heat pumps can be cost-competitive at existing carbon emission allowance prices (approximately 90€/tCO2) in the European emission trading system. For the assessed cases, with the emission trading scheme, the return on investment is less than six years and three years for case study vessels 1 and 2 respectively. The study also shows that operating a heat pump is more cost-effective than directly using electro-fuel in a boiler for thermal loads.

A Greenhouse Gas Budget for Mexico During 2000–2019

AbstractApplication of the best available science to improve quantification of greenhouse gas (GHG) emissions at regional and national scales is key to climate action. Here, we present a two‐decade (2000–2019) GHG (CO2, CH4, and N2O) budget for Mexico derived from multiple products. Data from the National GHG Inventory, global observations, and the scientific literature were compared to identify knowledge gaps on GHG flux dynamics and discrepancies among estimates. Total mean annual GHG emissions were estimated at 695–910 TgCO2‐eq year−1 over these two decades, with 70% of the emissions attributable to CO2, 23% to CH4, and 5% to N2O (2% to other gases). When divided by sectors, we found agreement across emission estimates from various sources for fossil fuels, cattle, agriculture, and waste for all GHGs. However, considerable discrepancies were identified in the fluxes from terrestrial ecosystems. The disagreement was particularly large for the land CO2 sink, where net biome production estimations from the national inventory were double those from any other observational product. Extensive knowledge gaps exist, mainly related to aquatic systems (e.g., outgassing in rivers) and the lateral fluxes (e.g., wood trade). In addition, limited information is available on CH4 emissions from wetlands and soil CH4 consumption. We expect these results to guide future research to reduce estimation uncertainties and fill the information gaps across Mexico.

Biogas and biohydrogen for net zero cooking and transportation in Bhutan

Agricultural biomass is a promising renewable energy material for Bhutan to support net zero transition of its cooking and transport sectors. In this study, crop residue and animal manure biomass-based biogas and biohydrogen potential of Bhutan are assessed at district and regional levels using a spatial framework. Existing energy demand of the cooking and transport sectors and associated greenhouse gases (GHGs) emissions are also estimated spatially. To analyze the net zero transition potential in the cooking and transport sectors, current energy situations of the sectors are compared with biogas-based cooking and biohydrogen-based transportation. It is observed that, annual biogas potential of Bhutan is 105 million cubic meter (mcm), equivalent to 2091 tera joule (TJ) energy. The potential is higher than the current cooking energy demand of 1230 TJ. At individual district level, 16 out of 20 districts can 100 % substitute LPG and firewood with biogas to support net zero transition of the cooking sector. Estimated annual GHGs emissions from the cooking sector are 102,089 t CO2eq. Transitioning to biogas-based cooking would provide significant GHGs emissions savings benefits for Bhutan. For example, annual emissions savings of 93,443 t CO2eq could be achieved through crop residue biogas-based cooking. Similarly, estimated biohydrogen potential (111 mcm, equivalent to 1194 TJ) can meet 35 % of current transportation energy demand (3353 TJ) of Bhutan. Full realization of the biohydrogen potential (1194 TJ) could provide annually 27,187 t CO2eq emissions savings in the transport sector of Bhutan. The findings of the present research could be useful for net zero transition of cooking and transport sectors of Bhutan. Thus, by leveraging the potential of biogas and biohydrogen, Bhutan can accelerate net zero transition and circular growth.

Using Atmospheric Inverse Modelling of Methane Budgets with Copernicus Land Water and Wetness Data to Detect Land Use-Related Emissions

Climate change mitigation requires countries to report their annual greenhouse gas (GHG) emissions and sinks, including those from land use, land use change, and forestry (LULUCF). In Finland, the LULUCF sector plays a crucial role in achieving net-zero GHG emissions, as the sector is expected to be a net sink. However, accurate estimates of LULUCF-related GHG emissions, such as methane (CH4), remain challenging. We estimated LULUCF-related CH4 emissions in Finland in 2013–2020 by combining national land cover and remote-sensed surface wetness data with CH4 emissions estimated by an inversion model. According to our inversion model, most of Finland’s CH4 emissions were attributed to natural sources such as open pristine peatlands. However, our research indicated that forests with thin tree cover surrounding open peatlands may also be a significant source of CH4. Unlike open pristine peatlands and pristine peatlands with thin tree cover, surrounding transient forests are included in the Finnish GHG inventory if they meet the criteria used for forest land. The current Finnish national GHG inventory may therefore underestimate CH4 emissions from forested organic soils surrounding open peatlands, although more precise methods and data are needed to verify this. Given the potential impact on net GHG emissions, CH4 emissions from transitional forests on organic soils should be further investigated. Furthermore, the results demonstrate the potential of combining atmospheric inversion modelling of GHGs with diverse data sources and highlight the need for methods to more easily combine atmospheric inversions with national GHG inventories.

Peering into a Simplified Digestor for Households: Performance, Cost and Carbon-Neutral Niche

In this study, a black-shading cylindrical water tank made of high-density polyethylene was locally manufactured as a household digestor for treating cow manure in Bangladesh. Effluent slurry instead of water was reused for manure dilution under manure-to-slurry ratios of 1:2 and 1:1, to assess this small prototype’s production efficiency and feasibility. The specific biogas production at both ratios matched well, by 0.12 m3/kg VS and 0.14 m3/kg VS, respectively, while the former slurry dilution operation outperformed in daily and accumulative biogas production by 16% and 57%, correspondingly, referring to 0.49 Nm3/d on average and 8.55 Nm3 in total, potentially meeting a 2 h household cooking energy requirement. From a nationwide viewpoint, slurry dilution was proven to be a great initiative to conserve water amounting to 50,286,751 m3 for 114,810 households of 6 person-equivalents annually, while cutting chemical costs by USD 32,720,684/yr and trimming annual greenhouse gas emission by 1.8 million tons of CO2e. This study revealed that a small prototype digestor could be an alternative energy source for cost-effective and eco-friendly household applications.