Publications

This POSTnote by Ellie Smallwood summarises the challenges and options for enabling and encouraging of low-carbon actions by individuals in sectors with the highest emissions, which from the research undertaken as part of her 3 month UKRI Internship with POST. 

Briefing produced for the Centre for Climate Change and Social Transformations (CAST), intended as a resource for decision-makers and other stakeholders who aim to improve the design and implementation of climate policy. The briefing outlines the potential opportunities presented by various types of 'moments of change' in reshaping travel behaviour, and their implications for policy.

The urgent need to combat global warming has spurred legislative efforts within the transport sector to transition away from fossil fuels. Hydrogen is increasingly being utilised as a green energy vector, which can aid the decarbonisation of transport, including internal combustion engines. Computational fluid dynamics (CFD) is widely used as a tool to study and optimise combustion systems especially in combination with new fuels like hydrogen. Since the behaviour of the injection event significantly impacts combustion and emissions formation especially in direct injection applications, the accurate modelling of H2 injection is imperative for effective design of hydrogen combustion systems.

This work aims to evaluate unsteady Reynolds-Averaged Navier Stokes (URANS) modelling of the advective transport process and related numerical methods. Measurements of H2 injection forming supersonic jets inside of constant volume chamber carried out at wide range of relevant conditions are utilised for validation. Investigations focused on aspects of simulated jet definition and its compatibility with Schlieren methods, cubic equations of state as well as probability of the relevant conditions inside the jet, use of adaptive mesh refinement (AMR), mesh dependency, convective flux and colocation methods, nozzle pressure ratio (NPR) effects and contribution of individual terms.

The paper recommends applying molar fraction of H2 to define the jet as well as utilising Soave-Redlich-Kwong as equation of state. Mesh dependency is found to be strongly influenced by nozzle kinetic power (NKP), but not by selection of the turbulence model. Advanced convective flux schemes with flux/slope limiters and colocation generalisation can effectively reduce numerical diffusion and dispersion errors. Finally, comparison of the simulations against physical experiments has shown a good agreement across a wide range of NPRs, proving the reliability of modelling the advection.

Recent legislation banning the sale of new petrol and diesel vehicles in Europe from 2035 has shifted the focus of internal combustion engine research towards alternative fuels with net zero tailpipe emissions such as hydrogen.

Research regarding hydrogen as a fuel is particularly pertinent to the so-called ‘hard-to-electrify’ propulsion applications, requiring a combination of large range, fast refuelling times or high-load duty cycles. The virtual design, development, and optimisation of hydrogen internal combustion engines has resulted in the necessity for accurate predictive modelling of the hydrogen combustion and autoignition processes.

Typically, the models for these processes rely respectively on laminar flame speed datasets to calculate the rate of fuel burn as well as ignition delay time datasets to estimate autoignition timing. These datasets are generated using chemical kinetic mechanisms available in the literature. However, these mechanisms have typically been developed with a focus on hydrocarbon oxidation – e.g., syngas, natural gas, biofuels, diesel, and gasoline - and their validation datasets feature a very limited number of hydrogen-specific targets.

Therefore, this study explores the predictive capability of six commonly used chemical kinetic mechanisms over a large dataset consisting of hydrogen-specific ignition delay time and laminar flame speed targets compiled using data available in the literature. Additionally, a sensitivity analysis was conducted to identify reactions that strongly affect the ignition delay time of hydrogen-air mixtures in the intermediate-temperature regime, where large ignition delay time deviations are observed compared to experimental results. The sensitivity analysis was followed by an exploratory study in ad-hoc mechanism adjustment.

In January 2023, Bath & North East Somerset Council (B&NES) implemented the first local planning policies in the UK requiring, first, that all new building developments achieve net zero operational energy, and second, that major developments meet an embodied carbon target. Both go far beyond the existing national building regulations, but they are representative of a growing number of similar policies from local authorities.

This paper describes a collaboration between B&NES and the University of Bath which explored the first months of the new policies’ implementation, to identify the impacts on building designs, the reception by practitioners, and opportunities for policy development and refinement. Thirty-eight eligible planning applications were analysed, the majority for minor residential buildings eligible only for the operational energy policy. Despite a non-compliance rate of over 50% – primarily caused by a lack of policy awareness – many applications for buildings theoretically achieving net zero operational energy were received, representing efficiencies far beyond current standards.

However, scrutiny and monitoring will be required for these ambitions to be met in practice. A corresponding questionnaire was completed by 65% of applicants. Although the responses were largely negative, with particular concerns over cost and viability, there was broad support for the policies’ aims and an expectation of long-term emissions savings.

A long-term study is now needed to track the evolving industry response, quantify the real emission savings through construction and occupation, and further engage with stakeholders to support the policies’ implementation, development, and wider impact.

This paper studies the single open-circuit failure (OCF) in dual three-phase permanent magnet synchronous motors (DT-PMSM) in transport electrification where wide speed range and torque operation range (TOR) are required.

A control scheme is developed to extend the TOR with minimum copper loss based on the well-established fault-tolerant control strategy minimum loss (ML) and maximum torque (MT). The ML strategy allows the demanded torque at the reference speed to be delivered with minimum copper loss. The MT strategy presents wider torque capability in post-fault operation without exceeding the current limit, whilst copper loss within the stator winding is not optimized.

However, there is a gap in the permissible TOR of these two strategies. A simple switch of strategy, from ML to MT when the limit of ML's TOR is reached, would result in excessive copper loss. The full-torque-operation-range minimum loss (FTOR-ML), inspired by previous work, is developed to mitigate the excessive copper loss, by analytically analysing the corresponding optimsation problems.

The FTOR-ML for the DT-PMSM under OCF for different winding configurations, single (1N) and isolated neutral point (2N), combines the merit of ML and MT where the entire TOR of MT is achieved with minimum copper loss. The novel analytical solution of FTOR-ML derived in this paper contributes to highly simplistic implementation for both winding configurations. Experimental result demonstrates the combined merit and effectiveness of the proposed control scheme.

Research on evaluating sustainable transport policies is predominantly focused on their urban effects, often overlooking similar challenges in suburban and rural mobility. Therefore, the development of regionally integrated sustainable transport strategies becomes essential to comprehensively address these concerns.

This study aims to bridge this gap by introducing a GIS-supported methodology that combines multiple linear regressions with hazard ratio models to quantify and map the impacts of environmentally driven regional transport policies on air pollution and human health. The main findings of an illustrative case study highlighted the importance of stronger efforts to promote the transition to shared and active transport and address the articulation between urban and rural mobility. 

This study offers a novel contribution to transport researchers and policymakers by proposing a methodology that (1) forecasts the impacts of regional transport policies using open data and software, ensuring its applicability for diverse regional settings, (2) provides the results in quantitative and visual formats, facilitating output analysis and visualisation and, consequently, decision-making and public consultation on proposed sustainable transport policies, and (3) sets the groundwork for including future transport-related dimensions.

Automotive OEM introduced Product-Service Systems in the past 20 years, challenging their traditional business model. A qualitative study was developed to characterise the decision-making process across 6 case studies, and similar patterns across different enabled the identification of lessons learned and possible future implications.

All PSS initiatives were introduced following an Agile/Lean experimental approach, but the opportunistic nature of trials casts doubts in future validity. New testing methods that generate more robust conclusions need to be developed.

In response to current environmental, social and accessibility challenges in the mobility sector, this research focuses on promoting the development of integrated sustainable regional transport policies, supported by a thorough analysis of their distributed economic impacts. This is fulfilled with the development of a new GIS-supported extension of a comprehensive methodology that is currently used for appraising local transport interventions.

To illustrate the inputs and outputs of the expanded approach, a regional case study was simulated, highlighting the potential for this methodology to assist in (1) optimising the financial balance between electrification and modal-shift strategies, (2) anticipating and analysing the multiple economic impacts of multimodal transport services (e.g., Mobility as a Service) and (3) understanding how equal the benefits of these policies are across the region. 

This research will provide novel contributions to the field of transport research and policy development by introducing a comprehensive methodology that quantifies and maps the distributed economic impacts of regional transport policies. This will, consequently, enable the economic outputs of these policies to be easily visualised, analysed and shared with mobility stakeholders, fostering a better understanding of their urban–rural distribution, and promoting the strategic development of sustainable and equitable regional transport systems.

The purpose of the research presented in this paper was to identify tools with the potential to assist project teams to work in a transdisciplinary (TD) manner. Research into transdisciplinary working tends to focus on theoretical and descriptive activities. Due to the social challenges being faced today, such as the climate emergency, TD working is gaining more traction. However, there is limited guidance to assist teams in working in a TD manner.

This paper contributes to providing practical and useable insights to assist TD working. Our research consisted of three stages, literature review, project team interviews and clustering of results. Stage 1: we identified through literature the attributes required by tools to have the potential to assist working in a TD manner, and identified tools that met these attributes. Seven attributes (shared purpose; stakeholders' collaboration inside and outside academia; reflection on disciplinary assumptions, biases, and perspectives; knowledge synthesis; integration of knowledge, perspectives, and methods; systems thinking; and co-creation of knowledge/solutions) and three tools were identified. Stage 2: a five-member project team to determine whether they were aware/considered the seven attributes, 60% of the team members were aware of five attributes, none of the tools were used. In stage 3, we undertook a thematic analysis to cluster the literature findings and the interview results. 

In conclusion, we found that multidisciplinary project teams may not be explicitly aware of TD attributes (although displayed TD attributes) and unaware of existing tools. Our next steps will be identifying how to utilise tools effectively.