Low Emission Mode Research Articles

Is a 15-Minute City Within Reach? Measuring Multimodal Accessibility and Carbon Footprint in 12 Major American Cities

Enhanced efforts in the transportation sector should be implemented to mitigate the adverse effects of CO2 emissions resulting from zoning-based planning paradigms. The concept of a 15-minute city, emphasizing proximity-based planning, holds promise in reducing unnecessary travel and progressing towards carbon neutrality. However, a critical research question remains inadequately explored: to what extent is the 15-minute city concept feasible for American cities? This paper presents a comprehensive framework to evaluate the 15-minute city concept using SafeGraph Point of Interest (POI) check-in data across 12 major American cities. Our findings suggest a prevailing reliance on cars among residents due to the spatial distribution of essential activities beyond convenient walking, cycling, and public transit distances. Nevertheless, there exists significant promise for realizing the 15-minute city vision, given that most residents' daily activities can be accommodated within a 15-minute radius by low-emission modes transportation modes. When comparing cities, it appears that achieving a 15-minute walking city is more feasible for metropolises like New York City, San Francisco, Boston, and Chicago, while proving to be challenging for cities such as Atlanta, Dallas, Houston, and Phoenix. In examing inter-group comparisons, neighborhoods with higher proportion of White residents and higher median incomes tend to have more accessible POIs, with a substantial percentage of activities concentrated within a 15-minute radius. This demographic also shows a greater propensity to fulfill daily activities through walking, cycling, or public transit trips within a 15-minute travel time, thus presenting a greater potential in CO2 reduction compared to African Americans. This study can offer policymakers insight into how far American cities are away from the 15-minute city concept. It also highlights the potential CO2 emissions reductions that could be achieved through successful implementation.

Tackling Car Emissions in Urban Areas: Shift, Avoid, Improve

Car use imposes costly environmental externalities. We investigate to what extent car trips could be shifted to low-emission modes, avoided via teleworking, or improved via a transition to electric vehicles in the context of daily mobility in the Paris area. We derive counterfactual travel times for 45,000 car trips from a representative transport survey, and formulate modal shift scenarios including a maximum acceptable increase in travel time. For a daily travel time increase below 10 min, 46% of drivers could shift to e-bike – mostly – or public transit – rarely –, with half of them benefiting from a travel time decrease. Such modal shift would reduce daily mobility emissions by 15% and generate annual climate and health benefits worth €125 million. Factors such as living in the far suburbs, being male, or having a high income, are associated with inability to shift modes. Teleworking two days a week could save an additional 5% of emissions. Holding demand for mobility and public transport infrastructure fixed, greater emission reductions require improving cars' environmental performance via a transition to electric vehicles.

A short-sea-shipping system for Liguria coast: first analysis at local, regional and cross-border scale

Maritime transport is a key-factor for economic and strategic development of Europe. Furthermore, similar activities have a very relevant impact on environment, climate, health and well-being of citizens. An updated version of the Combined Transport Directive is planned for the Third Quarter of the European Commission's activity, which supports transition from road freight transport to low-emission modes, such as inland waterways, maritime and rail transport. Within this complex framework, present paper outlines first considerations coming from two projects currently taking place in Northern Italy, and more specifically within Liguria Regional context: "viAmare" and "Mobimart Plus". The shared aim is to develop short "seaways" solutions for passenger and freight on a local, regional and cross-border scale (Italy / France), starting from Genoese metropolitan area as a pivotal site. First outcomes of the research, after an initial phase of ports’ selection according to boats general features, show the importance of verifying different economic service scenarios and connections of more performative quays with urban regeneration projects of the waterfront.

Best practice in urban transport decarbonisation: a case study of three initiatives in Brisbane

ABSTRACT Avoiding the worst impacts of climate change requires a transition to net-zero greenhouse gas emissions by mid-century, if not before. Urban transport systems are a significant contributor to emissions, so effective mitigation strategies for this sector are needed. This paper starts by outlining a best practice framework for transport decarbonisation based upon a review of the international research literature that entails: shifting passengers to net-zero or low-emission modes; investing in more energy-efficient technology options; and managing the demand for transport through a combination of land-use planning and socioeconomic policies. This best practice framework is then applied to a case study conducted in Brisbane (Australia) to see how the gap between the concepts developed in the research literature and the practice of making a change may be bridged. A policy analysis of three key transport initiatives in the city was undertaken to determine how they measure up against the best practice framework. On the positive side, Brisbane has the advantage of providing a reasonably reliable public transport system, expanding its bicycle/walking paths and engaging local communities in the decision-making and implementation. However, Brisbane faces a high degree of urban sprawl and car dependency, exacerbating its ecological footprint.

The low emission mode in PSR B0329+54

ABSTRACT We investigate properties of the low emission mode in PSR B0329+54 based on four single-pulse observations at frequency centred at 1.54 GHz using Nanshan radio telescope in Urumqi. The low emission mode is characterized by an intensity drop in the central component below that of the other two components. Referred here as the low mode, it has an average duration of 3P0 and is observed in both abnormal and normal emission modes of the pulsar occupying 3.6 per cent of the observed pulses. We demonstrate that the properties of low modes are related to the two modes. We find that the integrated profile of low modes is unique to the two modes, and that low modes occur more frequently when the pulsar is in the normal mode. Analysis of the energy distribution for normal low modes suggests that the cause for the intensity drop in the central component is separated from the emission of the other two components. We demonstrate that the pulse emission characteristics in the normal emission mode shortly after a low-mode bears some similarities with the abnormal mode and gradually recovering to the original normal emission in about three pulsar periods. In addition, the occurrence rate for low modes in different normal modes is mostly consistent, which implies that the duration of low modes is related to a normal mode for this pulsar. Our results imply profile modes each corresponds to specific magnetospheric plama density in particular geometric configuration, and profile mode changing signifies distinct changes of both at different parts of the profile.

Study of Sequential Two-Stage Combustion in a Low-Emission Gas Turbine Combustion Chamber

In this paper, we analyzed advanced ground-based power gas turbine units with low-emission combustion chambers used for consecutive two-stage fuel combustion. Such low-emission combustion chambers have a wide range of stable performance modes with reduced emission of harmful substances. The two-stage combustion chambers used in gas turbine units of various capacities—small (for example, M7A-03 with a capacity of approximately 8–10 MW), medium (L20A and L30A with a capacity of 18–30 MW) and large (9HA and GT36 with a capacity of over 300 MW)—showed their universality, efficiency, and good possibilities for scaling. The designs of low-emission combustion chambers for gas turbine units of different capacities are fundamentally similar. They consist of two sequentially located combustion volumes (stages), and each of them has its own burner unit. The first burner unit is typical for low-emission combustion chambers with the combustion of the premixed air-fuel mixture and consists of swirlers, mixing zone, fuel injectors, and igniters. The second burner unit is located downstream, and air-fuel mixtures of a different composition are supplied into it through special holes. The combustion of the mixtures occurs at a lower oxygen content and higher temperature. The ignition, work until idling, and loading before switching to the low-emission mode and switching to it are performed by the operation regulation of the first burner unit. Fuel in the second burner unit is supplied when a certain temperature of the gases arriving from the first combustion stage is achieved, which ensures its self-ignition. The further load is regulated by the fuel supply to the second burner unit. The design implementation of the sequential two-stage combustion scheme and approaches to regulating fuel and air distribution over the stages that ensures stable nonpulsating combustion are different and so they are of great scientific and practical interest.

Urban daily travel carbon emissions accounting and mitigation potential analysis using surveyed individual data

Abstract Our study focuses on the carbon emission and mitigation potential in the domain of daily travel in Beijing. Using a sample with the focus on working class, the average individual carbon emissions from daily travel are computed as 1.46 kg/day•person and 2.40 kg/day•person for weekday and weekend. Except for residents who need to conduct more long-distance trips, the main contributor to the emissions of the rest high emitters are not the need of longer daily travel distances or the need to conduct more long distance trips, but the need to use cars more intensively for trips with similar distances compared with low emitters. High emitters are associated with the characteristics of being male, having higher income, owning cars, and being in the age between 30s and 40s. On the other hand, living within fifth ring and having good accessibility to public transport are associated with lower emissions. We innovatively use trip-based information to obtain a more relevant and realistic assessment of mitigation potential through mode shift under the current transport system. The mitigation percentage can be as high as 20%–25% if only travel time is considered, but will be substantially constrained by practical barriers. Therefore mitigation policy for daily transport should not only focus on improving travel time of low emission modes to comparable levels with cars but also tackle practical barriers for car drivers to use low emission modes.

Reduction in nitrogen oxides emission on TGME-464 boiler of IRU power plant (Estonia)

The possibility for realization of measures on a reduction in nitrogen oxides emission on a TGME-464 (plant no. 2) boiler of the IRU power plant (Tallinn, Estonia) is investigated. Low-cost techno-logical measures, namely, nonstoichiometric burning and burning with the moderate controlled chemical underburning, are proposed and experimentally tested. Recommendations on the implementation of low-emission modes of burning natural gas into mode diagrams of the boiler are given. Nitrogen oxides emissions are reduced to the required level as a result of the implementation of the proposed measures.

Observations of a mode transition in a hydrogen hollow cathode discharge using phase resolved optical emission spectroscopy

Two distinct operational modes are observed in a radio frequency (rf) low pressure hydrogen hollow cathode discharge. The mode transition is characterised by a change in total light emission and differing expansion structures. An intensified CCD camera is used to make phase resolved images of Balmer α emission from the discharge. The low emission mode is consistent with a typical γ discharge, and appears to be driven by secondary electrons ejected from the cathode surface. The bright mode displays characteristics common to an inductive discharge, including increased optical emission, power factor, and temperature of the H2 gas. The bright mode precipitates the formation of a stationary shock in the expansion, observed as a dark region adjacent to the source-chamber interface.