Greenhouse Gas Mitigation Options Research Articles

Balancing farm profit and greenhouse gas emissions along the dairy production chain through breeding indices

Breeding is a promising greenhouse gas (GHG) mitigation option for the dairy sector that offers potential permanent and cumulative effects. However, there is limited understanding of how genetic traits affect GHG emissions from the dairy production chain and how breeding indices could be used to find a balance between GHG emissions and farm profit. Using a typical Chinese dairy farm as a case study, we developed a novel method to address these gaps. The farm comprised of 1523 Holstein-Friesian dairy cows and 1429 young stock. The average milk yield at the farm was 11,533 kg per cow per year. Life cycle assessment was combined with an existing bio-economic model to determine the emission intensity values (IV) of six genetic traits: milk yield, protein yield, fat yield, calving interval, productive life, and incidence of clinical mastitis. The IVs and economic values of the traits were used to form different breeding indices, of which the economic and environmental consequences were assessed. Results showed that for the next generation, breeding animals with optimal indices could reduce carbon dioxide equivalents per ton of fat-and-protein-corrected milk by six to 10 kg, while increasing profitability by 822 to 1355 Chinese Yuan per cow unit. Different indices can balance farm profit and GHG emissions to different degrees. However, the indices with higher profit showed less potential in reducing GHG emissions. This study provides insights into how breeding strategies could contribute to GHG mitigation in the dairy sector.

Modelling the effect of context-specific greenhouse gas and nitrogen emission mitigation options in key European dairy farming systems

Understanding the environmental consequences associated with dairy cattle production systems is crucial for the implementation of targeted strategies for emission reduction. However, few studies have modelled the effect of tailored emission mitigation options across key European dairy production systems. Here, we assess the single and combined effect of six emission mitigation practises on selected case studies across Europe through the Sustainable and Integrated Management System for Dairy Production model. This semi-mechanistic model accounts for the interacting flows from a whole-farm perspective simulating the environmental losses in response to different management strategies and site-specific conditions. The results show how reducing the crude protein content of the purchased fraction of the diet was an adequate strategy to reduce the greenhouse gas and nitrogen emission intensity in all systems. Furthermore, implementing an anaerobic digestion plant reduced the greenhouse gas emissions in all tested case studies while increasing the nitrogen emissions intensity, particularly when slurry was applied using broadcast. Regarding the productivity increase, contrasting effects were observed amongst the case studies modelled. Moreover, shallow slurry injection effectively mitigated the intensity of nitrogen losses from the fields due to strong reductions in ammonia volatilisation. When substituting urea with ammonium nitrate as mineral fertiliser, site-specific conditions affected the mitigation potential observed, discouraging its application on sandy-loam soils. Rigid slurry covers effectively reduced the storage-related nitrogen emissions intensity while showing a minor effect on total greenhouse gas emission intensity. In addition, our results provide novel evidence regarding the advantages of cumulative implementation of adapted mitigation options to offset the negative trade-offs of single-option applications (i.e. slurry covers or anaerobic digestion and slurry injection). Through this study, we contribute to a better understanding of the effect of emission mitigation options across dairy production systems in Europe, thus facilitating the adoption of tailored and context-specific emission reduction strategies.

A perspective on methodologies and system boundaries to develop abatement cost for on-farm anaerobic digestion

ABSTRACTMarginal Abatement Cost Curves compare and assess greenhouse gas mitigation options available to various sectors of the economy. In the Irish agricultural sector, large anaerobic digestion facilities are currently considered a high-cost abatement solution. In prior studies of anaerobic digestion abatement costs, two options were assessed: the generation of heat and electricity from biogas (115 €/tCO2eq) and the production of renewable heat from biomethane (280 €/tCO2eq). Both scenarios encompass single cost values that may not capture the potentially variable nature of such systems. In contrast, prior techno-economic analyses and lifecycle analyses can provide a comparison of the abatement costs of anaerobic digestion systems at a range of scales. This work compares two case studies (based on prior literature) for small and medium-scale on farm anaerobic digestion systems. The small-scale system is set in Ireland with cattle slurry collected in open tanks during the winter, while the medium-scale system is set in the USA with cattle slurry collected periodically indoors all year-round. It was found that the abatement cost can vary between −117 to +79 € per t CO2eq. The key variables that affected the abatement cost were additional revenue streams such as biofertilizer sales, displaced energy savings, and additional incentives and emissions savings within the system boundary. Including only some of these options in the analysis resulted in higher abatement costs being reported. Based on the variation between system topologies and therefore system boundaries, assigning a single mitigation cost to anaerobic digestion systems may not be representative.

Greenhouse Gas Mitigation Costs of Reduced Nitrogen Fertilizer

The reduction of nitrogen (N) fertilizer use is a possible greenhouse gas (GHG) mitigation option, whereas cost estimation highly depends on assumptions of the yield response function. This paper analyzes the potential and range of GHG mitigation costs with reduced N fertilizer application based on empirical yield response data for winter rye (Secale cereale L.) and rapeseed (Brassica napus L.) from field experiments from 2013 to 2020 in Brandenburg, Germany. The field experiments included four to five N rates as mineral fertilizer treatments. Three different functional forms (linear-plateau, quadratic, and quadratic-plateau) were estimated to model yield response as a function of N supply. Economic calculations were based on relevant price–cost ratios. The results indicate that the opportunity costs of applying less fertilizer and the resulting GHG mitigation thereof vary in a great range across the years and crops estimated by different yield response functions. The linear-plateau function predominantly results in lower GHG mitigation costs than the quadratic and the quadratic-plateau function. On average, over eight years, a moderate reduction of N fertilizer (up to 20 kg/ha) offers a cost-efficient option for mitigating GHG emissions below EUR 50 per ton of CO2eq, even resulting in net profit gain in some cases.

Intense Pasture Management in Brazil in an Integrated Crop-Livestock System Simulated by the DayCent Model

Process-based models (PBM) are important tools for understanding the benefits of Integrated Crop-Livestock Systems (ICLS), such as increasing land productivity and improving environmental conditions. PBM can provide insights into the contribution of agricultural production to climate change and help identify potential greenhouse gas (GHG) mitigation and carbon sequestration options. Rehabilitation of degraded lands is a key strategy for achieving food security goals and can reduce the need for new agricultural land. This study focused on the calibration and validation of the DayCent PBM for a typical ICLS adopted in Brazil from 2018 to 2020. We also present the DayCent parametrization for two forage species (ruzigrass and millet) grown simultaneously, bringing some innovation in the modeling challenges. We used aboveground biomass to calibrate the model, randomly selecting data from 70% of the paddocks in the study area. The calibration obtained a coefficient of determination (R2) of 0.69 and a relative RMSE of 37.0%. During the validation, we used other variables (CO2 flux, grain biomass, and soil water content) measured in the ICLS and performed a double validation for plant growth to evaluate the robustness of the model in terms of generalization. R2 validations ranged from 0.61 to 0.73, and relative RMSE from 11.3 to 48.3%. Despite the complexity and diversity of ICLS results show that DayCent can be used to model ICLS, which is an important step for future regional analyses and large-scale evaluations of the impacts of ICLS.

A Study on Selecting Greenhouse Gas Reduction Options: A Simulation Analysis for Vietnam

When it comes to greenhouse gas (GHG) mitigation, both bottom-up and top-down policies have limitations. Bottom-up policies are region-specific and cannot be applied at the national level. Top-down policies may not balance the considerations of economic growth and the environment. Therefore, a combined approach is necessary. This Vietnamese case study investigates optimal GHG mitigation options for both economic development and emission reduction by simulating four scenarios characterized by the different carbon tax and subsidy rates. Interventions, like replacing old buses with low-carbon buses and conventional electricity generation with solar power, are considered in a dynamic input–output framework. The objective function is Green GDP—industries’ total value added reflecting GHG emissions’ social cost. The simulation model comprises four cases: business as usual, low subsidy rate (up to 10%), medium subsidy rate (up to 20%), and high subsidy rate (up to 30%), which are analyzed on parameters, including economic development, GHG emissions, and development of innovative sectors, like transportation and electricity. In three cases with different subsidy rates, the optimal carbon tax is simulated at the rate of USD 1/tCO2 equivalent, the lowest rate among the world’s current carbon prices. In addition, the medium subsidy (up to 20%) option yields the most competent scheme, with the highest GHG emission reduction and economic development effectiveness.

Greenhouse gas mitigation technologies in agriculture: Regional circumstances and interactions determine cost-effectiveness

Agriculture, forestry and other land use are important components of a global strategy to limit climate change. Using the example of EU agriculture, this paper examines the potential contribution of technological (i.e. technical and management-based) greenhouse gas mitigation options to climate targets. The quantitative framework presented allows to analyze disparities between marginal abatement cost curves (MACCs) derived from two different commonly used approaches, and between aggregated and regional MACCs. Results highlight the importance of assessing mitigation of agricultural emissions from a multi-dimensional perspective, considering regional heterogeneity of biophysical and economic circumstances and comprising both carbon-dioxide (CO2) and non-CO2 emissions. Regarding the ranking of technologies in terms of mitigation potential and costs, the results underline the need to consider technologies in a combined manner, avoiding the simple aggregation of mitigation potentials by individual measures without taking their interactions into account. Focusing only on standalone MACCs can lead to an overestimation of the mitigation potential. Conversely, measures classified as relatively high cost in standalone and aggregated MACCs should not be discarded, as they can still be cost-effective in some regions. The analysis shows that there is no ‘one size fits all’ rule that could be followed for identifying technologies that should be implemented in all regions. From a policy perspective the results imply that farmers should be granted some flexibility to adopt a set of cost-effective mitigation options that best fits their circumstances.

Correction to: Gendered impacts of greenhouse gas mitigation options for rice cultivation in India

Correction to: Gendered impacts of greenhouse gas mitigation options for rice cultivation in India

Gendered impacts of greenhouse gas mitigation options for rice cultivation in India

The nexus of gender-agriculture-emissions reduction is one of the least explored areas related to agriculture and climate change. This nexus plays an important role in the areas where women’s participation in agriculture is high, and the contribution of the agricultural sector to total emission is significant. This study generates evidence on women’s labor contribution in rice cultivation and potential reduction of their labor drudgery, including GHG mitigation co-benefits with the adoption of direct seeding and machine transplanting technologies. Using a large number of plot-level data (11,987 data points) from the rice-growing regions of India, the study shows that changing rice production technology from conventional to direct-seeded rice (DSR) and/or machine-transplanted rice (MTR) offers huge potential to reduce women’s labor in rice planting (745 million labor-days for DSR and 610 million labor-days for MTR) and greenhouse gases (GHG) emission (34 MtCO2e for DSR and 7 MtCO2e for MTR) at the same time. This potential differs from the agro-ecological region, the level of input use, and women’s involvement in rice cultivation. The realization of this gender-responsive GHG mitigation strategy depends on the adoption of these technologies, which rely on several social, economic, and political factors. At the same time, the immense potential for negative implications for some specific groups should not be ignored, but focused on addressing and mitigating those challenges.

Assessing the economic and environmental impact of freight transport sectors in Thailand using computable general equilibrium model

In Thailand, the percentage of energy consumption and greenhouse gas (GHG) emissions in freight transportation sectors keep growing rapidly in the opposite side of GHG reduction target. The objective of this study is to evaluate the impacts on socio-economic status and GHG emissions in Thailand when introducing new greenhouse gas mitigation options in freight transportation sectors according to Thailand National Master Plan. This research constructed the country level dynamic multi-sector computable general equilibrium (CGE) model replicating the input-output table of Thailand in 2010 as a benchmark data. In this analysis the 3 scenarios have been assessed by CGE model. BaU represents the reference scenario that does not limit total GHG emissions. Using Thailand’s Nationally Determined Contribution (NDC) plan as mitigation target, NDC is the scenario that limits total GHG emissions in 2030 to 20% lower than BaU scenario. Then this study introduces mitigation options (S_all scenario) to freight transport sectors including road sector, rail sector and water sector under NDC mitigation target to assess the impact of new mitigation options on economic indicators and GHG emissions. As a result, NDC scenario showed that GDP and consumption in 2030 will drop by 2.1% and 3.5% respectively compared with those in BaU. Introducing mitigation options in freight transport sectors contributed to lower GDP loss and consumption loss by 1.04% and 0.9% respectively compared to NDC. It is also found that under GHG emissions limitation, GHG price will become effective and it will increase the cost of energy intensive goods in both industry and household sectors. Thailand economy may suffer loss from this reduction of energy intensive production; however, introduction of mitigation options in freight transport sectors will help compensate the production loss through the increase of production activities in low carbon energy intensive sectors.

Contrasting effects of different pH‐raising materials on N2O emissions in acidic upland soils

AbstractAcidic soils, occupying ca. 40% of the world's arable soils, often need to be managed (e.g., to raise their pH and to improve crop productivity); however, the environmental impact of raising soil pH is often difficult to assess. Increasing soil pH stimulates the reduction of N2O to N2, thus lowering N2O emissions associated with denitrification, but can also increase autotrophic nitrification rates and related N2O emission. Using a 15N tracing technique, we provide process‐based insights into the effects of two acid‐neutralizing materials (quicklime [CaO] vs. pig manure) on N2O emissions in an acidified upland soil that had experienced excessive N application. Without pH adjustments we found that N2O emissions, stimulated by supply of reactive N, were related to denitrification‐ and heterotrophic nitrification‐derived N2O emissions, whereas autotrophic nitrification‐derived N2O emissions declined with decreasing soil pH. These effects were reversed by increasing soil pH via liming. However, increasing the soil pH via application of pig manure significantly increased soil N2O emissions from both nitrification and denitrification. Our study highlights that pH‐amelioration practices may enhance N2O emissions depending on the type of material applied to the soil. Therefore, both pH remediation and greenhouse gas mitigation options need to be considered together to avoid adverse environmental effects. The effect of different acid‐neutralizing materials on soil N2O emissions should be incorporated into ecosystem models to better estimate global N2O emissions when pH amelioration is practised.Highlights Enhanced N2O emission by N input was from denitrification and heterotrophic nitrification. Chemical N input and liming have reversible effects on N2O emission. Soil N2O emission was decreased by liming but increased by animal manure input. Careful consideration of pH raising substrates is needed to avoid adverse effects.

Raising the groundwater table in the non-growing season can reduce greenhouse gas emissions and maintain crop productivity in cultivated fen peats

Fen peatlands represent a globally important carbon (C) store, while also providing highly productive agricultural land. Drainage of these organic soils is required to create conditions suitable for crop growth, but this results in substantial greenhouse gas (GHG) emissions. One potential GHG mitigation option is to raise the groundwater table to reduce the duration and volume of peat exposure to aerobic conditions. However, the trade-off between maintaining food production and securing ecosystem function under a high water table (WT) presents a serious challenge for both land managers and policy makers. Therefore, we conducted a controlled mesocosm experiment to investigate the effects of WT elevation (from −50 cm to −30 cm) under three contrasting scenarios: (i) WT raised throughout the year, (ii) WT raised in the winter only, and (iii) WT raised in the growing season only. We measured GHG emissions, nitrate, ammonium and dissolved organic C concentrations in soil solution, alongside the yield of a commercially important crop (lettuce). Raising the WT throughout the year reduced lettuce yields by 37% and reduced CO2 emissions by 36% without changing the loss rates of N2O or CH4. Raising the WT only in the winter did not significantly reduce crop yield, but still suppressed CO2 emissions during the fallow period (by 30%). Raising the WT only in the growing season reduced root growth and CO2 emissions (by 27%), but had no major effect on lettuce yield. In conclusion, the present study shows that raising the groundwater table in the non-growing season reduced GHG emissions without negatively affecting lettuce yields, and may therefore represent a viable GHG mitigation option for agricultural peatlands.

BASGRA_N: A model for grassland productivity, quality and greenhouse gas balance

The main objective of this paper is to present the new model BASGRA_N, to show how it was parameterized for grass swards in Scandinavia, and to evaluate its performance in predicting above-ground biomass, crude protein, cell wall content and dry matter digestibility. The model was developed to allow simulation of: (1) the impact of N-supply on the plants and their environment, (2) the dynamics of greenhouse gas emissions from grasslands, (3) the dynamics of cell-wall content and digestibility of leaves and stems, which could not be simulated with its predecessor, the BASGRA-model. To calibrate and test the model, we used field experimental data. One dataset included observations of biomass (DM) and crude protein content (CP) under different N fertilizer regimes from five sites in central and southern Sweden. The other dataset included observations of DM, and sward components as well as CP, cell wall content (NDF) and DM digestibility as affected by harvesting regime from one site in southwestern Norway. The total number of experiments was nine, of which three were used for model testing. When BASGRA_N was run with the maximum a-posteriori (MAP) parameter vector from the Bayesian calibration for the Swedish test sites, DM and CP were both simulated to an overall Pearson correlation coefficient (Rb) of minimum 0.58, Willmott's index of agreement (d) of minimum 0.69 and normalized root mean squared error (NRMSE) of maximum 0.30. Corresponding metrics for Norwegian test sites were 0.93, 0.96 and 0.27 for DM and >0.73, >0.61, <0.18 for DM digestibility, NDF and CP content, respectively. We conclude that BASGRA_N can be used to simulate yield and CP responses to N with satisfactory precision, while maintaining key features from its predecessor. The results also suggest that DM digestibility and NDF can be simulated satisfactorily, which is supported by results from a recent model comparison study. Further testing of the model is needed for a few variables for which we currently do not have enough data, notably leaching and emission of N-containing compounds. Further work will include application of the model to investigate greenhouse gas mitigation options, and evaluation against independent data for the conditions for which it will be applied.

The potential of Turkey's province-based livestock sector to mitigate GHG emissions through biogas production

Methane and nitrous oxide are the two leading greenhouse gases (GHG) that are released to the atmosphere due to livestock enteric fermentation and manure management. This study examines Turkey's province-based GHG emissions released by its livestock sector due to these processes. Besides, this study focusses on biogas production through anaerobic digestion, which is one of the most effective GHG mitigation options from manure management. This study aims to show the importance of the livestock sector in regards to GHG emissions in Turkey based on estimations made by the Intergovernmental Panel on Climate Change (IPCC) 2006 Guidelines. As a result of these estimations, for the year 2015, 33.85 million tons of carbon dioxide equivalent (CO2-eq) were produced from enteric fermentation and manure management system.The study also aims to evaluate Turkey's province-based biogas production potential from animal manure through the anaerobic digestion (AD) technology. Two different biogas potential scenarios with varying manure recovery rates were developed. Scenario 1 was developed based on the assumption of that total amount of produced animal manure would be used in AD for biogas production, and scenario 2 was developed based on the realistic manure recovery rates that vary with the type of livestock. Biogas potentials for scenario 1 and scenario 2 were determined as 8.41 billion m3 and 4.18 billion m3 in 2015, respectively. These values can meet Turkey's total electricity demand at a rate of 5.25% for scenario 1, and the rate of 2.3% for scenario 2. In addition, according to Turkey's GHG Inventory, submitted annually to the United Nations Framework Convention on Climate Change (UNFCCC), GHG emissions from manure management can be reduced by 1.13% through biogas production.

Developing Green: A Case for the Brazilian Manufacturing Industry

The recent IPCC Special Report on global warming of 1.5 °C emphasizes that rapid action to reduce greenhouse gas (GHG) emissions is vital to achieving the climate mitigation goals of the Paris Agreement. The most-needed substantial upscaling of investments in GHG mitigation options in all sectors, and particularly in manufacturing sectors, can be an opportunity for a green economic development leap in developing countries. Here, we use the Brazilian manufacturing sectors as an example to explore a transformation of its economy while contributing to the Paris targets. Projections of Brazil’s economic futures with and without a portfolio of fiscal policies to induce low carbon investments are produced up to 2030 (end year of Brazil’s Nationally Determined Contribution—NDC), by employing the large-scale macro econometric Energy-Environment-Economy Model, E3ME. Our findings highlight that the correct mix of green stimulus can help modernize and decarbonize the Brazilian manufacturing sectors and allow the country’s economy to grow faster (by up to 0.42% compared to baseline) while its carbon dioxide (CO2) emissions decline (by up to 14.5% in relation to baseline). Investment levels increase, thereby strengthening exports’ competitiveness and alleviating external constraints to long-term economic growth in net terms.

Assessment of greenhouse gas mitigation options for the iron, gold, and potash mining sectors

Abstract The objective of this study is to investigate greenhouse gas mitigation pathways for the iron, gold, and potash mining sectors in Canada. These sectors have not widely accepted the available cleaner production strategies and so there is potential to reduce greenhouse gas emissions. It is important to fully realize this potential as soon as possible to support efforts to limit global warming. We conducted cost-benefit analyses of implementable greenhouse gas reduction strategies in order to inform policy and industry. Twenty-four greenhouse gas emission reduction options not yet implemented in Canada were identified following a review of current processes and operations at 102 mine sites. We developed a novel model to assess these options, integrating technology diffusion rates and long-term energy-environmental modelling. We found that the maximum greenhouse gas reduction potential can be realized through simultaneously implementing fifteen technology changes, eliminating 21 million tonnes of CO2 eq. by 2050. Furthermore, we showed that the marginal greenhouse gas abatement costs are negative, indicating that the industry would also achieve long-term cost savings if these changes were pursued. Implementing high pressure grinding rolls in iron mining and electric and diesel hybrid haul trucks in underground gold mining and potash mining have the most favorable greenhouse gas abatement costs of −4120, −3096, −701 $/tonne, respectively. These results show that these technology changes should be pursued since both environmental benefit and cost savings would be achieved.

Excreta emissions in progeny of low and high enteric methane yield selection line sheep fed pasture of different qualities

Selection of sheep with low enteric methane (CH4) emissions is a greenhouse gas (GHG) mitigation option suitable for pastoral systems. However, the effect of breeding sheep with low enteric CH4 emissions on excreta output and associated CH4 and nitrous oxide (N2O) emissions and therefore total GHG emissions are not known. The objective of the current experiments were to determine excreta output, and estimate associated GHG emissions, from progeny of low and high enteric CH4 per unit of dry matter intake (DMI) selection line sheep (CH4/DMI). The animals were fed two qualities of cut perennial ryegrass-based pasture (very mature vs. vegetative, 12 animals per CH4/DMI line) in Exp. 1 and cut pasture in two repeated seasons (autumn and winter; 15 animals per CH4/DMI line × 2 seasons) in Exp. 2. Total faecal and urine output was determined on individual animals, followed by enteric CH4 emission measurements in respiration chambers. GHG emissions from urine (N2O) and faeces (CH4 and N2O) were estimated based on New Zealand Agricultural GHG Inventory methodology. There was no interaction between CH4/DMI selection line and diet quality in Exp. 1 or seasons in Exp.2. Total daily faecal output of DM, organic matter (OM) and neutral detergent fibre (NDF; all g/d) and associated calculated faecal CH4 emissions were greater for low compared to high CH4/DMI sheep in Exp. 1 (P < 0.05), while being similar between CH4/DMI selection lines in Exp. 2. Nitrogen (N) excretion and N partitioning into urine, faeces and body retention, and calculated excreta N emissions, were mostly similar between CH4/DMI selection line sheep in both experiments. Except, faecal N output (g/d and per unit of N intake) and associated calculated direct faecal N2O-N emissions (g/d) were greater in low compared to high CH4/DMI sheep in Exp. 1 (P < 0.05). Enteric CH4 emissions were numerically 8% less (P = 0.15) in Exp.1 and 10% less (P = 0.004) in Exp. 2 and total animal level GHG emissions (CH4 and N2O) were numerically 7% less (P = 0.21) in Exp. 1 and 8% less (P = 0.006) in Exp.2 for progeny of the low compared to the high CH4/DMI line sheep. In conclusion, the magnitude of difference in enteric CH4 (expressed as CO2-equivalent) between low and high CH4/DMI selection line sheep were still present when CH4 from faeces and N2O emissions from urine and faeces were also accounted for. The animal genetic traits were expressed independent of environmental factors, i.e. pasture quality and season.

Assessment of energy demand-based greenhouse gas mitigation options for Canada's oil sands

Abstract The main objective of this study is to assess energy-use reduction strategies in extraction and upgrading of oil sands for greenhouse gas mitigation in Canada's oil sands sector. A bottom-up integrated resource-planning model for oil sands extraction and upgrading processes was developed. The model is a novel application of an energy accounting-based framework and accurately simulates energy demand and supply in the oil sands from 2007 to 2050. Thirty energy-use reduction scenarios were evaluated covering in situ extraction, surface mining, and bitumen upgrading processes. The energy savings, greenhouse gas emission mitigation, and costs associated with each scenario were determined with the model. Implementing in situ energy-use reduction measures resulted in the highest single measure greenhouse gas mitigation potential of 86 million tonnes CO2e at a marginal greenhouse gas abatement cost of -$91/tonne of CO2e by 2050. For the scenarios in surface mining and bitumen upgrading, the highest single measure greenhouse gas mitigation potentials are 17 and 16 million tonnes CO2e by 2050 at marginal greenhouse gas abatement costs of -$65/tonne of CO2e and -$21/tonne of CO2e, respectively. All strategies result in a negative $/tonne of CO2e cost, indicating a net benefit for investing in the strategies. If the strategies are implemented together, there is an ultimate potential to reduce sector-wide cumulative energy consumption and greenhouse gas emissions in the oil sands by 8% and 7%, respectively, by 2050. Decision-makers at company or government levels can use these results to support both environmental and cost-saving initiatives.

The Hestia fossil fuel CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emissions data product for the Los Angeles megacity (Hestia-LA)

Abstract. High-resolution bottom-up estimation provides a detailed guide for city greenhouse gas mitigation options, offering details that can increase the economic efficiency of emissions reduction options and synergize with other urban policy priorities at the human scale. As a critical constraint to urban atmospheric CO2 inversion studies, bottom-up spatiotemporally explicit emissions data products are also necessary to construct comprehensive urban CO2 emission information systems useful for trend detection and emissions verification. The “Hestia Project” is an effort to provide bottom-up granular fossil fuel (FFCO2) emissions for the urban domain with building/street and hourly space–time resolution. Here, we report on the latest urban area for which a Hestia estimate has been completed – the Los Angeles megacity, encompassing five counties: Los Angeles County, Orange County, Riverside County, San Bernardino County and Ventura County. We provide a complete description of the methods used to build the Hestia FFCO2 emissions data product for the years 2010–2015. We find that the LA Basin emits 48.06 (±5.3) MtC yr−1, dominated by the on-road sector. Because of the uneven spatial distribution of emissions, 10 % of the largest-emitting grid cells account for 93.6 %, 73.4 %, 66.2 %, and 45.3 % of the industrial, commercial, on-road, and residential sector emissions, respectively. Hestia FFCO2 emissions are 10.7 % larger than the inventory estimate generated by the local metropolitan planning agency, a difference that is driven by the industrial and electricity production sectors. The detail of the Hestia-LA FFCO2 emissions data product offers the potential for highly targeted, efficient urban greenhouse gas emissions mitigation policy. The Hestia-LA v2.5 emissions data product can be downloaded from the National Institute of Standards and Technology repository (https://doi.org/10.18434/T4/1502503, Gurney et al., 2019).

Reducing methane emissions from abandoned oil and gas wells: Strategies and costs

Well plugging, the main strategy for reducing methane emissions from millions of unplugged abandoned oil and gas (AOG) wells in the U.S. and abroad, is expensive and many wells remain unplugged. In addition, plugging does not necessarily reduce methane emissions and some categories of plugged wells are high emitters. We analyze strategies and costs of five options for reducing methane emissions from high-emitting AOG wells - those which are unplugged and plugged/vented gas wells. The five options are: plugging without gas venting, plugging with gas venting and flaring, plugging with gas venting and usage, gas flaring only, and gas capture/usage only. Average plugging costs ($37,000 per well) can be justified by the social cost of methane, which considers air quality, climate, and human/ecosystem impacts. Savings as measured by natural gas prices and alternative energy credits can offset low plugging costs (<$15,400 per well) but are not large enough to offset average plugging costs. Nonetheless, reducing methane emissions from AOG wells is a cost-effective strategy for addressing climate change that has comparable costs to some current greenhouse gas mitigation options and can produce co-benefits such as groundwater protection. Therefore, we recommend including the mitigation of AOG wells in climate and energy policies in the U.S., Canada, and other oil-and-gas-producing regions.