杭州市三江汇地区森林植被固碳抵消能源 排放能力评估及情景预测研究

森林植被固碳服务是生态系统服务评估的重要内容之一，在区域碳中和发挥着重要的碳汇作用。以生物量法和CASA模型法相结合，评估杭州市三江汇地区森林植被固碳能力；采用CEADs县级碳排放清单估算三江汇地区的能源碳排放量；综合碳汇和碳排评估该地区森林植被固碳对能源碳排放量的抵消率。从碳减排和增汇2个方面，对森林植被抵消能源碳排放的能力进行未来情景预测。研究结果表明：1)2017年三江汇地区森林植被固碳量为4.98×10⁴t，能源碳排放量为2.07×10⁶t，森林植被能源碳排放的抵消率为2.41%，三江汇森林植被能源碳抵消率呈现出“东低西高、北低南高”的空间格局；2)研究设置9个情景对2030年森林植被碳抵消率进行定量预测，预测结果显示研究区森林植被面积增加有利于提升森林植被对能源碳排放量的抵消能力，森林面积每增加5%，森林植被对能源碳排放量抵消率可提高0.12%～0.29%；减少人均能源碳排放对提高森林植被碳抵消能力的效果更为显著，人均能源碳排由2.77t/人降低为0.90和0.72t/人，森林植被碳抵消率可分别提高2.21%～2.43%和3.36%...     

Adoption of conservation easements among agricultural landowners in Colorado and Wyoming: The role of economic dependence and sense of place

The inter-mountain west is one of the most highly urbanized and rapidly growing regions in the United States. Conservation easements are one common tool used to protect rural and agricultural land from urban development. This paper examines the attitudinal and demographic characteristics of agricultural landowners to predict adoption of conservation easements. The study has two primary objectives: (1) to broaden the literature on sense of place and place attachment by including a measure of economic dependence as one dimension, and (2) to examine the relation of this dimension with attitudes towards land trusts and participation in conservation easements. Agricultural landowners (N = 2266) in Colorado and Wyoming were surveyed about their sense of place for their land, their attitudes towards land trusts, and perceived need for land conservation. Factor analysis of 12 measures of sense of place indicated that place identity, conservation ethic, and economic dependence ere distinct dimensions of sense of place among agricultural landowners. Logistic regression analyses revealed that economic dependence had a significant and negative relation with landowner's trust of and trusts and placement of a conservation easement on agricultural land, whereas a conservation ethic and spiritual attachment are positively related. Two main implications for land trusts are that time spent contacting landowners is time well spent and intake questionnaires could be used to screen and owners for both a conservation ethic and a sense of economic dependence providing information hat might improve the possibility of reaching an easement agreement.     

Carbon sequestration potential of spotted gum (Corymbia citriodora subspecies Variegata) in South East Queensland,Australia

The objectives of this study were to determine the carbon sequestration potential of spotted gum forest plantation in the South East Queensland region and to determine the suitability of the whole area to carbon sequestration endeavour. This information is indispensable to stakeholders when considering land use options particularly carbon sequestration. A process-based model and geographic information system were employed in the process. The site has a potential biomass production of 1422–2329?ton?ha^?1 with the carbon dioxide equivalent range from 2539 to 4157?ton?ha^?1 in 100?year of rotation period. The maximum mean annual growth of 19.98?m³ ha^?1 was estimated in the Great Sandy sub-region while the lowest value of 11.46?m³?ha^?1 was predicted in South Burnett sub-region. The findings indicated that the whole region has a high potential carbon sequestration capability but requires further spatial suitability and economic analysis.     

碳中和背景下城市碳汇功能及提升策略——以沈阳核心区为例

城市是碳排放产生的主要地域空间,是进行"碳中和"核算与政策制定的主体.除了减少固定能源与交通碳排放外,增加城市碳汇也是实现"碳中和"的重要手段.通过分析沈阳三环区域城市碳汇(植被、土壤、水系、建筑物)不同组成部分的碳汇能力,估算出城市碳汇固碳量为430.93万t,能够抵消沈阳市年能源消耗产生CO2的7.34％.在明晰城...     

Fighting Traffic: The Dawn of the Motor Age in the American City

Problem: Suburban areas have an important role to play in reducing greenhouse gas (GHG) emissions, yet little is known about the magnitude of reductions that can be expected or which strategies are most promising. Local GHG reduction strategies are often capital investments such as new green buildings, ignoring the promise of operational strategies.

Purpose: The research is intended to support local planning efforts for GHG reduction in areas where land uses are separated and transit use is low. It is also intended to contribute to the dialogue on the potential for local actions versus broader state, federal, or international initiatives.

Methods: Using the California State Polytechnic University, Pomona (CPP) campus in eastern Los Angeles County as a case study, this ex ante evaluation estimates the cost effectiveness of eight capital and operating GHG-reduction strategies. It uses locally developed estimation methods in combination with the Clean Air-Cool Planet GHG inventory model.

Results and conclusions: Carbon neutrality in suburban areas is a fantasy unless there are supportive energy, transportation, and carbon sequestration initiatives at the state, national, and international level. We find that local operational strategies, such as online classes and alternative scheduling, green energy purchase, and parking pricing and carpool programs have merit. Greater results are achieved when operational strategies are combined with cost-effective capital investments such as land use mixing (in this case, on-campus housing). Even so, some of the most favored capital approaches, such as a new green building or building commuter rail transit station facilities, rank near the bottom in cost effectiveness.

Takeaway for practice: Given the urgency of reducing GHG emissions, local planners and activity center managers should evaluate both capital and operating strategies and implement the most cost-effective strategies in new and existing development.

Research support: Support for this research was provided by the President's Office, California State Polytechnic University, Pomona.     

Increase in carbon emissions from forest fires after intensive reforestation and forest management programs

This paper shows an example of substantial increase in carbon emissions from forest fires after reforestation on a national scale. It is the first estimation of historical carbon emissions from forest fires in Korea during the last 40 years. Investigation was focused on the recent increase in large forest fires and its closely related factors. A simple modeling approach to estimate carbon emission was applied. The direct carbon emission from forest fires in 2000, ranging from 115 to 300 Gg C, corresponds to 1-3% of the annual carbon uptake by forests. The influence of forest fires on the carbon cycle in Korea is not so significant, but Korean forests have a large potential for generating severe local fires due to increasing forest carbon density and a high forest area ratio (forest area/total land area) of 65%. The carbon emission per area burned (Mg C ha(-1)) clearly reflects the trend toward increases in the number of severe fires. Statistical analyses and the trends of annual temperature and precipitation show that the recent large increase in carbon emissions may be the negative consequences of intensive forest regrowth that is the product of successful reforestation and forest management programs rather than the effect of climate change. These results imply a need for further studies in other countries, where large-scale plantation has been conducted, to evaluate the role of plantation and forest fires on the global carbon cycle.     

Influence of injection timing on engine performance,emission characteristics of Mimusops Elangi methyl ester

ABSTRACT

The improvement in engine performance and exhaust emissions reduction are the major important issues in developing a more efficient engine. The injection timing is one the major parameters that affect the engine performance and emissions for a diesel engine. The present work focused on characterising the in?uence of injection timing on engine performance and exhaust emissions. This has been critically investigated for B20?+?25?ppm (20% Mimusops Elangi methyl ester-80% diesel fuel?+?25?ppm of TiO₂ nanoparticle) additive as alternative fuel. The B20?+25 ppm TiO₂ nanoparticle additive produces more HC and CO emission, but reduce NO_X emission when injection timing is retarded. Advancement in injection timing for B20?+25?ppm TiO₂ nanoparticle additive results in an increase of brake thermal efficiency, decreases brake specific fuel consumption and giving out less HC, CO, smoke emissions but the marginal increase in the NO_X emission.     

The Purchase of Scenic Easements and Wisconsin's Great River Road

In the early 1950s, Wisconsin initiated the nation's first major state-supported program to acquire conservation easements when it began to purchase scenic easements on land along the highways adjacent to the Mississippi River-the Great River Road. This program became an early model for other conservation easement acquisition programs in the nation. Today, programs to purchase conservation easements are still viewed as an important planning tool for permanently protecting land from development; yet, very little is understood about the true nature of such protection. This article examines the experiences of Wisconsin's Great River Road program in an effort to begin to understand the constraints and limitations to the “perpetual” protection offered by conservation easements. Conservation easements can be modified or terminated; they can also be subject to political influence. I conclude that placing a conservation easement on a parcel of land is not the final step in achieving long-term protection. Conservation easement holders must formulate a long-term strategy to uphold the intent of these easements and ensure that their use remains in the public interest.     

Is Compact Growth Good for Air Quality?

Problem: Explicitly prohibited from regulating the land use planning activities of municipal and county governments by the Clean Air Act (42 U.S.C. 131), the U.S. Environmental Protection Agency (EPA) has been forced to pursue an end-of-the-pipe approach to air quality management that has not proved successful in fully reducing ozone and fine particulate matter below health-based standards in many large U.S. cities. The persistence of these pollutants, in combination with a rapid rise in vehicle travel in recent decades, has raised concerns within the planning and public health communities about the long-term success of an air quality management program that is effectively divorced from the land use planning process.

Purpose: This work, which is part of an EPA-sponsored study titled Projecting the Impact of Land Use and Transportation on Future Air Quality (PLUTO), was intended to assess the effectiveness of compact growth in improving air quality at a geographic scale compatible with secondary pollution formation and transport and over a planning horizon sufficient to capture the longer-term benefits of regional land use change.

Methods: Future air quality is associated with alternative land development scenarios in this study through the integration of three separate and previously unrelated modeling components. These components consist of a set of standard population projection techniques, a household vehicle travel activity framework, and a mobile source emissions model (MOBILE 6) developed by the EPA.

Results and conclusions: The results of our analysis find the median elasticity of vehicle travel with respect to density change over time to be ?0.35, suggesting metropolitan areas can expect a 10% increase in population density to be associated with a 3.5% reduction in household vehicle travel and emissions. In addition, vehicle elasticities derived for urban and suburban census tracts across the 11 metro regions suggest density increments within urban zones (?0.43) to be more than twice as effective in reducing vehicle travel and emissions as density increments within suburban zones (?0.19).

Takeaway for practice: We found compactness to be associated with greater reductions in vehicle travel than in previous studies, which suggests land use change can play a measurable role in improving regional air quality over time. Importantly, we found where compact growth occurs to be critically important to determining the extent to which higher density development reduces vehicle travel and emissions. We found the densifi-cation of urban zones to be more than twice as effective in reducing vehicle miles of travel and emissions as the densification of suburban zones, suggesting compact growth to be better for air quality than historical patterns of growth when densifying urban zones is given priority over non-urban zones.     

The carbon footprint of urban green space—A life cycle approach

Cities play an important role in the global carbon cycle. They produce a large proportion of CO₂ emissions, but they also sequester and store carbon in urban forests and green space. However, sequestration by urban green space is difficult to quantify and also involves emissions. The carbon footprint analysis is an established method for systematically quantifying carbon sinks and sources throughout the lifetime of goods and services. We applied this method to an urban green space project in Leipzig, Germany. To the best of our knowledge it is the first application in this field. We simulated carbon sequestration by growing trees and contrasted it with all related carbon sources, from construction and maintenance over the lifetime of 50 years. In addition, we explored alternative design and maintenance scenarios. Total net sequestration was predicted to be between 137 and 162 MgCO₂ ha⁻¹. Park-like design and maintenance is less effective than forest-like design and maintenance. Much uncertainty is linked to tree growth and tree mortality. Increasing annual tree mortality from 0.5 to 4% reduces sequestration by over 70%. In conclusion, urban green space can act as a carbon sink and the design and maintenance have a strong influence on the carbon footprint. The carbon footprint analysis is a valuable tool for estimating the long-term environmental performance of urban green space projects. Compared to emissions from people, the overall potential for carbon mitigation is limited, even in cities such as Leipzig with widely available space for new urban green space.     

Quantifying spatial-temporal changes of aboveground carbon stocks using Landsat time series data: A case study of Miombo woodlands

ABSTRACT

There is a need for accurate reporting of the second-growth forest in accounting for the contribution of secondary forests to achieving global carbon sequestration strategies. This study develops a model relating aboveground live biomass (AGLB) to Landsat reflectance measurements, and this method is used on multi spatial-temporal Landsat data (1998, 2001, 2004, 2011 and 2016) to assess changes in Miombo woodlands in Zambia. Results showed that the enhanced vegetation index was a better predictor of AGLB (r² = 0.96; RMSE = 0.24 t ha^?1) than the other assessed vegetation indices. Forest carbon stocks increased by an average rate of 3.65 ± standard error (SE): 0.56 t ha^?1 yr^?1 from 1998 to 2001, but a continual decline was evident for the periods 2001–2004 (?0.60 t ha^?1 yr^?1), 2004–2011 (?0.88 t ha^?1 yr^?1) and 2011–2016 (?2.03 t ha^?1 yr^?1). The study provides an empirical model for evaluating carbon stock changes.     

Experimental investigation of a spark ignition engine using blends of biogas

ABSTRACT

Biogas from cow dung is one of the best fuels that readily mixes with gasoline and yields less emission and better performance on gasoline engines. In this study, an attempt has been made experimentally on a gasoline engine operating with enriched and compressed biogas blends B10, B20 and gasoline. A significant increase in specific consumption and reduction in brake thermal efficiency of the engine was observed. Exhaust gas emissions were measured and analysed for hydrocarbons (HC), carbon dioxide (CO₂), carbon monoxide (CO) and oxides of nitrogen (NO_X) at an engine speed of 2000rpm. The concentrations of CO, CO₂ and HC emission were found to be decreased and increased trend in NOx for biogas blends.     

Effect of compression ratio on nano-particle doped fuel blends in unmodified research engine

ABSTRACT

Compression ratio is a significant factor among different parameters which governs the emissions and performance factors of the research engine. This work portrays the effect of compression ratio (CR) on cerium oxide nano-particle doped biodiesel and diesel blends. The doping is made at 30, 60 and 90?ppm. The modified fuels are introduced in different compression ratio of 16, 18 and 20. 1500?rpm research engine is made use in this study. Result revealed a significant reduction in emissions (CO, HC and Smoke) at CR?=?20. Further, Performance (BSFC, BTE) is improved for fuel blends at CR?=?20.     

Effect of intake air oxygen enrichment for improving engine performance and emissions control in diesel engine

Stringent emission regulations and health awareness about air pollution have led researchers to find alternative means of minimising emissions in diesel engines. In this article, the influence of oxygen enrichment is discussed to determine the effect on diesel engine performance, emission characteristics and combustion characteristics. Normal diesel and oxygen-enriched diesel are used in this experiment. The increase in oxygen concentration led to complete combustion, producing higher thermal efficiency and low harmful emissions. From the results, it is noted that oxygen-enriched diesel fuel showed reduction of CO, HC and smoke emissions, while NOx emission increased.

Abbreviations/Nomenclature DI: direct injection; NOx: oxides of nitrogen; O₂: oxygen; HC: hydrocarbon; PM: particulate matters; CO: carbon monoxide; CO₂: carbon dioxide     

Influence of injection timing on cerium oxide nanoparticle doped in waste cooking palm oil bio-diesel and diesel blends fuelled in diesel engine

ABSTRACT

Injection timing (IT) is a vital factor among different injection parameters which governs the emissions and performance factors of the engine. This work portrays the effect of IT on cerium oxide nanoparticle doped Waste Cooking Palm Oil biodiesel and diesel blends. The doping is made at 30, 60 and 90?ppm. The modified fuels are introduced in reducing IT of 19°, 21° and 23°bTDC. 1500?rpm engine is made use in this study. Results revealed a significant reduction in emissions (CO, NO_X, HC and Smoke) at IT?=?23°bTDC. Furthermore, performance (BSFC, BTE) is improved for fuel blends at IT?=?23°bTDC.     

利用TOUGH2进行场地规模CO2地质封存的模拟方法

温室气体排量的增加,对人类的可持续发展造成了严重的影响。减少CO2的排量是人类急需解决的问题。作为有效的CO2减排途径,CO2地质封存技术发展前景乐观。本文首先从理论上详细介绍基于TOUGH2进行场地规模CO2地质封存数值模拟所采用的方法,说明了空间离散,边界条件的刻画,模型参数的获取,初始条件的确定以及不同注入方式下注入井的设置。以鄂尔多斯盆地的场地规模CO2地质封存为例,在TOUGH2-MP/ECO2N软件平台的支持下,介绍数值模拟的过程,并简要给出了数值模拟的结果,验证了这一过程的可行性。     

Statehouse Versus Greenhouse

Problem: In the absence of U.S. federal action to address the problem of climate change, a diverse array of nonfederal policy entrepreneurs and climate action planners has produced an impressive body of plans and policies to fight climate change at the regional, state, and local levels. Their actions are highly laudable, but have they actually reduced greenhouse gas (GHG) emissions?

Purpose: This article evaluates the work of a group of innovative state-level policy entre-preneurs whose actions were chronicled by Barry Rabe, and a set of 29 state climate action plans systematically analyzed by Stephen Wheeler. It compares states with and without climate policy entrepreneurs and states with and without climate action plans, asks if either plans or entrepreneurs have been successful in reducing CO2 emissions, and identifies the elements within plans that are associated with the greatest reductions.

Methods: The analysis uses multiple regression models to explain changes in per capita CO2 emissions attributable to residen-tial, commercial, transportation, and total nonindustrial end users from 1990 to 2007. A package of control variables accounts for political, social, climatic, economic, and urban form factors, while policy variables isolate the effects of climate policy entrepre-neurs, climate action planners, and specific policy recommendations within climate action plans.

Results and conclusions: State-level climate actions reduce GHG emissions by a measurable but modest amount: about one half metric ton per person per year. This represents 2–3% of the average American's 24-ton annual total GHG emissions. The reduction is small in comparison to the magnitude of the problem, but a substantial tax increase or population shift away from sprawling areas would be necessary to achieve the same reduction. specific policies I find to be associated with lower emissions include: building efficiency in both residential and commercial sectors, Leadership in Energy and Environmental Design (LEED) policies in the commercial sector, and California's vehicle efficiency standards in the transportation sector.

Takeaway for practice: It is encouraging that we can already identify emission reduc-tions related to state climate action. However, the observed reductions remain small com-pared to the scope of the problem. These findings should persuade states without plans to begin the planning process while encourag-ing states with plans to encourage more entrepreneurship aimed at developing a second generation of policy options for stabilizing our planet's climate with or without federal action.

Research support: None.     

HOUSING POLICY GOALS AND THE TURNOVER OF HOUSING

Problem: Congestion pricing and land use planning have been proposed as two promising strategies to reduce the externalities associated with driving, including traffic congestion, air pollution, and greenhouse gas emissions. However, they are often viewed by their proponents as substitutive instead of complementary to each other.

Purpose: Using data from a pilot mileage fee program run in Portland, OR, we explored whether congestion pricing and land use planning were mutually supportive in terms of vehicle miles traveled (VMT) reduction. We examined whether effective land use planning could reinforce the benefit of congestion pricing, and whether congestion pricing could strengthen the role of land use planning in encouraging travelers to reduce driving.

Methods: VMT data were collected over 10 months from 130 households, which were divided into two groups: those who paid a mileage charge with rates that varied by congestion level (i.e., congestion pricing) and those who paid a mileage charge with a flat structure. Using regression models to compare the two groups, we tested the effect of congestion pricing on VMT reduction across different land use patterns, and the effect of land use on VMT reduction with and without congestion pricing.

Results and conclusions: With congestion pricing, the VMT reduction is greater in traditional (dense and mixed-use) neighborhoods than in suburban (single-use, low-density) neighborhoods, probably because of the availability of travel alternatives in the former. Under the same land use pattern, land use attributes explain more variance of household VMT when congestion pricing is implemented, suggesting that this form of mileage fee could make land use planning a more effective mechanism to reduce VMT. In summary, land use planning and congestion pricing appear to be mutually supportive.

Takeaway for practice: For policymakers considering mileage pricing, land use planning affects not only the economic viability but also the political feasibility of a pricing scheme. For urban planners, congestion pricing provides both opportunities and challenges to crafting land use policies that will reduce VMT. For example, a pricing zone that overlaps with dense, mixed-use and transit-accessible development, can reinforce the benefits of these development patterns and encourage greater behavioral changes.

Research support: This project was supported by the Mineta Transportation Institute, where the authors are research associates.     

Study on the outcome of a cetane improver on the emission characteristics of a diesel engine

ABSTRACT

Dimethyl carbonate (DMC), a cetane improver, is used as a fuel additive to investigate the exhaust emission in diesel engine. Neem oil biodiesel (B100), neem oil biodiesel + dimethyl carbonate (B100+DMC) and diesel were used as test fuels. DMC is added 0.5% by volume to biodiesel. This research work was executed in a four-stroke, single-cylinder diesel engine. Owing to the percentage of DMC in biodiesel, carbon monoxide (CO) and hydrocarbon (HC) emissions were dropped corresponding to diesel. A considerable amount of nitrogen oxide (NO_x) is decreased when diesel is used, and by the addition of B100+DMC, NO_x were slightly reduced compared to B100.     

Rethinking Federal Housing Policy

Problem: Federal housing policy is made up of disparate programs that a) promote homeownership; b) assist low-income renters’ access to good-quality, affordable housing; and c) enforce the Fair Housing Act by combating residential discrimination. Some of these programs are ineffective, others have drifted from their initial purpose, and none are well coordinated with each other.

Purpose: We examine the trends, summarize the research evaluating the performance of these programs, and suggest steps to make them more effective and connected to each other.

Methods: We review the history of housing policy and programs and empirical studies of program effectiveness to identify a set of best principles and practices.

Results and conclusions: In the area of homeownership, we recommend that the federal government help the nation's housing markets quickly find bottom, privatize aspects of the secondary mortgage market, and move to eliminate the mortgage interest deduction and replace it with a 10-year homeownership tax credit. In the area of subsidized rental housing, we recommend that the current system of vouchers be regionalized (or alternatively, converted into an entitlement program that works through the income tax system), sell public housing projects to nonprofit sponsors where appropriate, and eliminate some of the rigidities in the Low Income Housing Tax Credit program. In the area of fair housing, we recommend that communities receiving Community Development Block Grants be required to implement inclusionary zoning programs.

Takeaway for practice: In general, we recommend that federal policy build on proven programs; focus on providing affordable housing for low- and moderate-income families and provide the funding to meet that goal; avoid grandiose and ideological ambitions and programs; use fewer and more coordinated programs; offer tax credits, not tax deductions; and promote residential filtering.

Research support: Partial funding support was provided by the National Science Foundation.