Climate Benefits Research Articles

Climate and air pollution impacts of generating biopower from forest management residues in California

California faces crisis conditions on its forested landscapes. A century of aggressive logging and fire suppression in combination with conditions exacerbated by climate change have created an ongoing ecological, economic, and public health emergency. Between commercial harvests on California’s working forestlands and the increasing number of acres the state treats each year for fire risk reduction and carbon sequestration, California forests generate millions of tons of woody residues annually—residues that are typically left or burned in the field. State policymakers have turned to biomass electricity generation as a key market for woody biomass in the hope that it can support sustainable forest management activities while also providing low-carbon renewable electricity. However, open questions surrounding the climate and air pollution performance of electricity generation from woody biomass have made it difficult to determine how best to manage the risks and opportunities posed by forest residues. The California Biomass Residue Emissions Characterization (C-BREC) model offers a spatially-explicit life cycle assessment framework to rigorously and transparently establish the climate and air pollution impacts of biopower from forest residues in California under current conditions. The C-BREC model characterizes the variable emissions from different biomass supply chains as well as the counterfactual emissions from prescribed burn, wildfire, and decay avoided by residue mobilization. We find that the life cycle ‘carbon footprint’ of biopower from woody residues generated by recent forest treatments in California ranges widely—from comparable with solar photovoltaic on the low end to comparable with natural gas on the high end. This variation stems largely from the heterogeneity in the fire and decay conditions these residues would encounter if left in the field, with utilization of residue that would otherwise have been burned in place offering the best climate and air quality performance. California’s energy and forest management policies should account for this variation to ensure desired climate benefits are achieved.

Soil, litter and vegetation carbon for the 6 simulations performed in CLM5 of "Chemistry-albedo feedbacks from reforestation reduce climate benefits and crop yields"

Soil, litter and vegetation carbon for the 6 simulations performed in CLM5 of "Chemistry-albedo feedbacks from reforestation reduce climate benefits and crop yields"

Negligible carbon costs of UHVDC infrastructure delivering renewable electricity

Ultra-high voltage direct current (UHVDC) transmission make it possible for efficient large-scale long-distance renewable energy deliver, while the infrastructure construction consumes significant amounts of material and energy. The carbon tradeoffs are often overlooked, however, hindering a holistic evaluation of its climate benefits. Here, by collecting field construction data from fifteen 500 kV transmission projects and applying the field data in a Life Cycle Assessment framework, we estimate the infrastructure-induced emissions of nine recently-constructed UHVDC projects in China to be 16.7 Mt CO2, which is negligible compare to an annual reduction of 305.2 Mt CO2 these projects contribute by delivering renewable electricity at full load, multiplied by a 40-yr service lifetime. The tradeoff results may evolve with advancing energy storage technology at exporting region or CCUS application at importing region. Low-carbon strategies for UHVDC construction are therefore favored, especially under China's commitment to expanding UHVDC construction along the Belt and Road Initiative.

Quantify the Contribution of Nature-Based Solutions in Reducing the Impacts of Hydro-Meteorological Hazards in the Urban Environment: A Case Study in Naples, Italy

Urban areas are vulnerable to multiple risks associated with hydro-meteorological hazards (HMHs). The assessment of the climate benefits of implementing nature-based solutions (NBSs) in urban areas, especially in open spaces, is widely recognised and discussed within the scientific literature; however, the quantification of these benefits, in terms of the HMHs reduction, human safety and human well-being, is still a subject of debate. In this context, this contribution proposes a methodological approach that, starting from the analysis of the impacts of coastal flooding and in terms of the potential direct and tangible economic damages, heatwave events and vulnerability of open spaces, proposes the application and assessment of NBSs in terms of the reduction in these impacts. The process was developed in the GIS environment based on the processing of open-source data. The test was conducted in the case study of Naples’ waterfront to identify the potentialities and limitations of the approach. The results showed the contribution of NBSs in reducing the economic damages due to coastal flooding and the improved vulnerability conditions to heatwave events.

Supplementary Data and code for "Soil organic carbon change can reduce the climate benefits of biofuel produced from forest residues"

Supplementary Data and code for "Soil organic carbon change can reduce the climate benefits of biofuel produced from forest residues"

Visualizing and assessing the 15-minute city facility configuration of city region A study on the Beijing-Tianjin-Hebei Urban Agglomeration

The desire for a more liveable, highly interconnected and people-oriented city is driving a surge of interest in the ’15-minute city’, an intuitive, adaptable and popular vision of urban living that already takes place around the world. Elements of the 15-minute city have helped to manage urban life effectively globally by offering a way to build on positive changes to boost local economies and deliver lasting health, well-being, equity and climate benefits. As the COVID-19 pandemic continues to unfold and health concerns remain paramount, the strategy are already supporting cities towards recovery. As an important engine of global urbanization, the future development of China’s cities is threatened by increasing air pollution, traffic congestion, social inequalities and other pressures. In May 2021, the Ministry of Natural Resources of China released The Standard of Spatial Planning Guidance Community Life Unity to offer technique support for future 15-minute city construction. Taking a 15-minute walking distance as the space scale, the Guidance configures various functions and facilities required for basic living of residents, ad provides a construction reference for healthy, energetic and low-carbon lifestyle, which satisfies urban residents’ yearning for a better life. Furthermore, the Guidance offers a detailed spatial assessment framework of 15-minute city facilities deployment including a variety of parameters. Based on the Beijing-Tianjin-Hebei Urban Agglomeration, this paper evaluates the integrated performance of 13 cities in the Agglomeration by using the framework of the Guidance for visualizing and exploring facilities’ POIs on POI-type semantic space. The compare of 15-minute community construction between different cities is rendered as a “mode map” by POI counts on various types, providing a vivid information delivery method for urban planners and POI-related urban studies and applications.

Potential of land-based climate change mitigation strategies on abandoned cropland

Natural revegetation, afforestation, and lignocellulosic crops for bioenergy, possibly coupled with a developing technology like carbon capture and storage, are the most common land-based climate change mitigation options. However, they can compete for land and threaten food security or nature conservation. Using abandoned cropland for their deployment can minimize these risks, but associated potentials are unclear. Here, we compare alternative land-based mitigation options by integrating historical and future (up to 2050) abandoned cropland with site-specific biomass yields and life-cycle emissions. Considering natural revegetation in biodiversity priority areas and different measures in the remaining land can achieve a mitigation potential of 0.8–4.0 GtCO2-equivalents yr−1 (2–11% of 2021 global CO2 emissions). Afforestation generally provides larger climate benefits than bioenergy, but bioenergy with carbon capture and storage delivers the highest mitigation in most locations. Overall, these results offer refined estimates of mitigation potentials from abandoned cropland and highlight opportunities for context-specific mitigation measures.

The Health and Climate Benefits of Economic Dispatch in China's Power System.

China's power system is highly regulated and uses an "equal-share" dispatch approach. However, market mechanisms are being introduced to reduce generation costs and improve system reliability. Here, we quantify the climate and human health impacts brought about by this transition, modeling China's power system operations under economic dispatch. We find that significant reductions in mortality related to air pollution (11%) and CO2 emissions (3%) from the power sector can be attained by economic dispatch, relative to the equal-share approach, through more efficient coal-powered generation. Additional health and climate benefits can be achieved by incorporating emission externalities in electricity generation costs. However, the benefits of the transition to economic dispatch will be unevenly distributed across China and may lead to increased health damage in some regions. Our results show the potential of dispatch decision-making in electricity generation to mitigate the negative impacts of power plant emissions with existing facilities in China.

Pathways to achieving nature-positive and carbon–neutral land use and food systems in Wales

Land use and its management can play a vital role in carbon sequestration, but trade-offs may exist with other objectives including food security and nature recovery. Using an integrated model (the FABLE calculator), four pathways, co-created with colleagues at the Welsh Government, towards achieving climate and biodiversity targets in Wales were explored: status quo, improvements on current trends, land sparing and land sharing. We found that continuing as usual will not be sufficient to meet Wales’s climate and biodiversity targets. In contrast, the land use and agricultural sector became a net carbon sink in both the land sparing and land sharing pathways, through high afforestation targets, peatland restoration, reducing food waste and moving towards a healthier diet. Whilst both pathways released land for biodiversity, the gains were greater in the land sharing pathway, which was also less dependent on optimistic assumptions concerning productivity improvements. The results demonstrate that alternative approaches to achieving nature-positive and carbon–neutral land use and food systems may be possible, but they come with stringent and transformative requirements for policy changes, with an integrated approach necessary to maximise benefits for climate, food and nature.

Energy, Cost, and Environmental Assessments of Methanol Production via Electrochemical Reduction of CO2 from Biosyngas

Electrochemical reduction of CO2 removed from biosyngas into value-added methanol (CH3OH) provides an attractive way to mitigate climate change, realize CO2 utilization, and improve the overall process efficiency of biomass gasification. However, the economic and environmental feasibilities of this technology are still unclear. In this work, economic and environmental assessments for the stand-alone CO2 electrochemical reduction (CO2R) toward CH3OH with ionic liquid as the electrolyte and the integrated process that combined CO2R with biomass gasification were conducted systematically to identify key economic drivers and provide technological indexes to be competitive. The results demonstrated that costs of investment associated with CO2R and electricity are the main contributors to the total production cost (TPC). Integration of CO2R with CO2 capture/purification and biomass gasification could decrease TPC by 28%–66% under the current and future conditions, highlighting the importance of process integration. Energy and environmental assessment revealed that the energy for CO2R dominated the main energy usage and CO2 emissions, and additionally, the energy structure has a great influence on environmental feasibility. All scenarios could provide climate benefits over the conventional coal-to-CH3OH process if renewable sources are used for electricity generation.

Evaluation of Methane Emissions in Daily Operations and Accidents: A Case Study of a Local Distribution Company in China

As the second-largest contributor to historical global warming, methane emissions must be controlled to slow down temperature increase and achieve climate benefits. Due to a lack of knowledge about the specific sources and processes, a quantitative approach will lead to inaccurate estimation. In this paper, a typical local distribution company with more than 100 years of operation history was chosen. Detailed procedures of pipeline constructions and accidents were investigated, and critical steps leading to methane emissions were clarified. Then emission quantification methodologies for all processes were proposed, including a new pipeline connection, new regulator connection, emergency repair and third-party damages. As a basis for emission estimation, the distribution of parameters, such as diameter, length and pressure, was counted. Then the emission rates of all projects were calculated, and emission factors were established. The average emission rates of the new pipeline connection, new regulator connection, emergency repair, third-party damage (medium pressure) and third-party damage (low pressure) were 234 kg, 147 kg, 217 kg, 17,282 kg and 62 kg, respectively. In addition, the total methane emission in China from these sources was estimated to be about 5 × 104 t, which is large enough to attract attention. The work in this paper aims to establish a reasonable framework to evaluate venting methane emissions from the distribution process of natural gas.

Synergy between pollution control and carbon reduction: China's evidence

The proposal of dual carbon goals indicates that China's overall ecological environment protection will focus on carbon reduction in the future. Our concern is whether the existing environmental regulatory policies focusing on pollutants emission have a synergistic effect on carbon reduction. Based on China's 11th Five-Year Plan, this paper examines the synergy between pollution control and carbon reduction by using the data at China's “province-industry-year” level and constructing a difference-in-difference-in-differences analysis framework. The results show that the implementation of the 11th Five-Year Plan has significantly reduced the CO2 emissions of polluting industries in provinces with stricter environmental regulations, which means that it has played an important role in promoting carbon neutrality. Moreover, the mechanism analysis suggests that the 11th Five-Year Plan can achieve CO2 reduction through energy substitution and technological innovation, but the effect of the energy structure transformation is not significant. The results also indicate that climate benefit was realized at the cost of declining output and employment. The findings of this paper contribute to an in-depth understanding of the synergistic system of reducing pollution and carbon emissions and provide empirical evidence for formulating development strategies and policies to achieve synergies, which has important practical guiding significance.

Breathing Room: Cleaner Fuels for Home Cooking in LMICs.

Breathing Room: Cleaner Fuels for Home Cooking in LMICs.

Climate benefits of seaweed farming

Climate benefits of seaweed farming

Climate mitigation potential of sustainable biochar production in China

While feeding 20% of global population, China's agriculture is a large greenhouse gas (GHG) emitter, posing a major challenge to the country's carbon neutrality target. However, the pathways of agriculture towards carbon neutrality remain unclear. To address this knowledge gap, we conduct a comprehensive life-cycle assessment and show that valorization of sustainable biomass wastes (crop residues, forest residues, livestock manure, food waste, and sewage sludge) into biochar can contribute importantly towards agricultural carbon neutrality in China. The maximum potential of biochar production from these waste resources in 2018 is 145 Mt yr−1 with a corresponding GHG mitigation potential of 455.7 (405.5–572.4) Mt CO2-eq yr−1. This can fully offset the total CH4 and N2O emissions from China's croplands (∼400 Mt CO2-eq yr−1), which are difficult to be entirely eliminated due to rice paddy irrigation and intensive use of fertilizers. Distribution of biomass waste varies across regions, and at the national level , crop residues (48.8%) and livestock manure (25.4%) and food waste (15.6%) are the main sources of biochar feedstocks and should be prioritized in biochar development. Forest residues have a marginal contribution due to competing uses from other sectors, and sewage sludge derived biochar is a net source of GHG emissions due to the large energy consumption required for sludge drying. The total GHG mitigation potential of biochar is greatly affected by pyrolysis temperature and the highest mitigation effect is observed under 300–500 °C. These results underscore the benefit of sustainable biochar production to agricultural carbon neutrality, and to maximize the climate benefit requires differential policies and pyrolysis technologies tailored to regional availability of biomass resources.

Life Cycle Based GHG Emissions from Algae Based Bioenergy with a Special Emphasis on Climate Change Indicators and Their Uses in Dynamic LCA: A Review

Life cycle-based analysis is a key to understand these biofuels’ climate benefits. This manuscript provides a state-of-the-art review of current biofuel production, primarily through algae-based routes. Standalone biofuel production has an unfavorable environmental and energy footprint. Therefore, industrial symbiosis is required to reduce the environmental impacts of biofuel. The availability of waste heat, CO2, renewable energy, and colocation of other industries, especially renewable energy and dairy firms, have been demonstrated beneficial for producing biofuel through the algal route. Dynamic life cycle assessment (DLCA) issues were discussed in detail. DLCA is one of the highlighted areas of the Life Cycle Assessment (LCA) paradigm that can improve the applicability of climate change indicators used in the LCA. Various climate change indicators, global warming potential (GWP), global temperature change (GTP), and climate tipping point (CTP) were discussed in detail. Special emphasis was given to waste-based bioenergy production and its LCA as this route provided the lowest GHG emissions compared to the other bioenergy production pathways (e.g., from energy crops, using lignocellulosic biomass, etc.). The use of LCA results and modification of life cycle inventory (e.g., modification in the form of the regional energy mix, dynamic Life Cycle Inventory (LCI), etc.) was another highlight of this study. Such modifications need to be incorporated if one wants to improve the applicability of LCA results for net zero target analysis.

By-production, emissions and abatement cost–climate benefit of HFC-23 in China's HCFC-22 plants

After the Kigali Amendment (KA) came into effect, HCFC-22 plants are obliged to limit HFC-23 emissions. Therefore, the study of cost-effective mitigation pathways for HFC-23 is important for the sustainable implementation of KA in China and other HCFC-22 producing countries. This study constructed an inventory of HFC-23 by-production, emissions, and abatement for HCFC-22 plants in China from 2006 to 2020, and predicted the costs and climate benefits of HFC-23 abatement in China's compliance with the KA between 2021 and 2060. Results showed that HFC-23 emissions from HCFC-22 plants in China contributed about 60% of the growth in global atmospheric mole fraction of HFC-23 observed by Advanced Global Atmospheric Gases Experiment (AGAGE) from 2007 to 2020. Furthermore, China's cumulative HFC-23 abatement was about 109 kt (1613 Mt CO2-eq) from 2006 to 2019, accounting for 53% of total by-production, which allowed the global atmospheric mole fraction and radiative forcing of HFC-23 in 2020 to avoid an uplift of 9.2 × 10−9 and 1.7 mW m−2, respectively, contributing to climate change mitigation. Under the baseline of the Kigali Amendment, less emission (LE), and resource utilization (RU) scenarios, the cumulative HFC-23 abatement from 2021 to 2060 would be 683 ± 29 kt (10,107 ± 431 Mt CO2-eq), 694 ± 29 kt (10,277 ± 427 Mt CO2-eq), and 702 ± 29 kt (10,385 ± 426 Mt CO2-eq), respectively. The cumulative net abatement costs for the KA, LE, and RU scenarios would be (5.0 ± 0.2) billion, (2.9 ± 0.2) billion, and (−2.7 ± 0.2) billion CNY (2021 prices), respectively. In the future, applying resource utilization technology to reduce HFC-23 emissions can achieve both climate and economic benefits.

Using Green Roofs for Social Housing to Improve Energy Consumption in New Cities. (An Applied Study of Social Housing in Egypt’s New Cairo City)

Green roofs are an effective way to solve many environmental problems. New cities in Egypt have recently suffered from increasing energy consumption as a result of increasing construction density resulting from population growth, which has decreased green spaces in Egyptian cities. This paper aims to improve the energy consumption of cooling and heating energy in social housing in new urban cities in Egypt, reduce high temperatures inside and outside building, and decrease the urban heat island effect. To achieve these aims, the study suggests a method that is based on modifying the traditional roof of residential construction in Egypt by converting it to a green roof. An integrated analysis model including a strategy shows the environmental and climatic benefits of using green roofs to provide the external outdoor temperature of social housing buildings. The result revealed that green roofs, which are used by 50% of green roofs in traditional buildings, were shown to be efficient in reducing annual energy consumption by 12% and decreasing the average temperature inside buildings by 2.44°C, whereas the average temperature outside was reduced by 3°C.

Sources and sequestration rate of organic carbon in sediments of the bare tidal flat ecosystems: A model approach

Humans have been contributing adversely to greenhouse gas emissions by generating a vast amount of CO2, primarily causing climate change. Nature-based climate solutions, consisting of both terrestrial and marine ecosystems, are tremendous potential for sequestering and storing significant amounts of carbon, which can help to slow the progression of climate change. In this study, we use a carbon balance model to simulate the carbon sequestration rate and carbon stored in bare tidal flat (BTF) areas along Korea's west and south coasts from 2018 to 2050. Furthermore, the percentage of potential carbon sources deposited at BTF sites was calculated using a two-terminal mixing model and δ13C data. The carbon deposited on the BTF areas is the result of lateral carbon transport from upslope terrestrial regions as well as marine sources. Based on the δ13C isotope, this study classified potential carbon sources in BTFs sediment into two categories: terrestrial and marine. The results indicate that the proportion of organic carbon contribution from terrestrial sources ranged from 7.63% to 49% in the BTF studied areas. We discuss the validity of projection which was investigated over three years, from 2018 to 2020. A preliminary conclusion is that future carbon storage at BTF sites will increase significantly. Carbon accumulation increases linearly over time in nearly all areas studied, with carbon sequestration rates ranging from 0.053 to 0.623 (MgC ha−1 yr−1). This study found that a significant amount of carbon is sequestered for a long time in the BTF regions based on model simulation results. In addition, it also contributes to projects that seek to promote and conserve these climate benefits by providing estimates of carbon storage in coastal BTFs that can be included in NDCs for the Paris Agreement.

Declining Renewable Costs, Emissions Trading, and Economic Growth: China’s Power System at the Crossroads

As China reaffirms its commitments to limit the climate change risk and improve air quality, a combination of new policy and technology opportunities is presenting itself. A national emission trading scheme (ETS) begun in 2017 and is showing great promise, creating decentralized incentives for cost effective pollution mitigation. At the same time, sustained energy sector innovation is driving the costs of renewable electric power generation below those of fossil fuel substitutes. Early economic evidence of ETS measured pollution reductions, but has not addressed important economy-wide net benefits. This paper focuses on technology and energy cost savings and is the first to account for three multiplier effects—shifting consumption patterns, job growth, and the benefits of induced productivity growth—that would result from accelerated renewable electricity deployment in China. Results from a dynamic recursive computable general equilibrium model for 2017 to 2030 show that expanding renewable deployment can interact with the ETS to slash GHG emissions, as well as energy costs, stimulating significant long-term economic growth. These results suggest that China should accelerate its clean energy transition, not only for the air-quality and climate benefits, but to fulfill the energy sector’s potential to promote innovation, employment, and economic growth.