Vacancies

I currently have the following PhD project available. Please contact me for further details.

Sustainable use of Urban Groundwater with Ground Source Heat Pumps

Heating and cooling buildings can account for up to half UK energy use and a similar proportion of carbon emissions. To meet our targets for carbon emissions reductions and to deliver net zero homes, it is essential that the heating of buildings is decarbonised. As the carbon intensity of the electricity grid reduces this makes use of ground source heat pump (GSHP) technology increasingly attractive. GSHP systems operate in conjunction with ground heat exchangers (GHEs) which transfer heat to or from the geological units beneath the building. Where flowing groundwater is present, the effective thermal properties of the ground are improved, leading to higher efficiency GHE and hence GSHP systems. However, the increased ability for heat dissipation comes with an increased volume of the sub-surface which is effected by the resulting thermal pollution. This brings a risk of raising aquifer temperatures and hence making future GHSP systems less sustainable.

As more GSHP systems are installed in congested urban areas, the risks of over exploitation of the aquifer will increase, with the potential for thermal interference between systems, hence reducing the energy availability in the long term. Open loop GSHP systems which extract water directly from aquifers require licensing, thus offering some control of the aquifer exploitation. However, closed loop GSHP systems where the GHE comprises a closed plastic pipe loop installed in the ground are not regulated in any way. While the extent of the downstream thermal pollution will be less with closed loop systems compared with open loop systems, the extent of the induced temperature changes in the aquifer can still span 10’s or even 100’s of metres in some cases.
This project will look at the long term impact of closed loop GSHP systems installed in aquifers beneath urban areas, and how they may interact with other systems to effect the thermal resource available. Different types of aquifer will be investigated, from classic Darcy flow to aquifers dominated by fracture flow and with high dispersivity. The project will lead to recommendations about aquifer characterisation for design, GSHP system density, operating conditions, and regulatory requirements for different hydrogeological conditions.

This project is funded as part of the Panorama DTP, click here for details.

Assessment of the Potential for Sedimentation in Infrastructure Drainage using Novel coupled CFD-DEM Analysis

There are tens of thousands of kilometres of transport infrastructure in Great Britain. To prevent flooding, maintain performance of railway track and road foundations, and to reduce the risks of slope instability in associated embankments and cuttings, drainage infrastructure is also installed. Most drains comprise coarse granular material of high permeability, and may also include a geotextile and a pipe to aid water removal.

The primary method of degradation of drain performance is the accumulation of sediment, which can initially reduce permeability and flow rates, ultimately leading to total blockage with inherent risks of flooding or slope failure. Hence maintenance is frequently required to retain serviceability. However, there is still little knowledge about the rate at which deterioration occurs. Better understanding this, to more appropriately and proactively plan maintenance, would have a positive impact on infrastructure asset management. This project will use novel coupled CFD-DEM (discrete element) modelling, validated against small scale experiments, to simulate the movement of fine sediment particles within drains under different design scenarios. The project aims to provide a better understanding of the factors effecting the rate of sedimentation to help plan, design and maintain drainage solutions.

This project is currently unfunded. Please contact me if interested.

Reducing GHGs from the heat system – Implementation of buried infrastructure as a heat source

The UK Government has a commitment to reduce greenhouse gas emissions by at least 80% by 2050. While the last five years has seen a 50% reduction in carbon density of the electricity grid, the target is unlikely to be met without also tackling the gas network.

This is because gas, principally used to provide space heating delivers over twice the energy of the electricity grid. With an ever decreasing carbon intensity of electricity, one of the best routes to decarbonise heating is through use of ground thermal energy storage coupled with ground source heat pump systems. However, heat pump systems retain high investments costs, mainly due to the expense of drilling dedicated ground heat exchangers (GHE).

Efforts to reduce these up-front costs include using dual purpose buried civil engineering structures as GHE and for structure support. This technique has been successful for foundation piles, but is now being developed for other infrastructure such as metro systems, underground carparks, and water and wastewater infrastructure.

One of the challenges with these new types of GHE is that the heat user is not the same as the infrastructure owner meaning there are additional barriers to implementation. Depending on the number and nature of the heat users it may also require adoption of district heating networks (DHN) which adds an additional complexity.

This PhD project will make the first academic study of how infrastructure sourced ground thermal energy can be integrated with adjacent heat users, including via district heating.

The project will make use of a range of interdisciplinary methodological approaches including quantitative appraisal off technical systems, as well as qualitative policy assessment to:

  • determine the number, range and types of users most suitable to different types of infrastructure GHE using DHN models; this will depend on the nature of the underground space and whether there is an embedded heat source such as train breaking.
  • ascertain the nature of the financial and non-technical barriers to implementation of these solutions using a combination of financial and agent based modelling.
  • make recommendations about measure to incentivise change and increase uptake of infrastructure based GHE in support of national climate targets.

The project will span engineering and environmental disciplines and will include aspects of civil and mechanical engineering, economics, social science, and policy to provide a holistic approach to the problem in the context of both construction industry practices and energy policy and practice.

This project is currently unfunded. Please contact me if interested.

Thermal Energy from Rail and Sewer Tunnels

The provision of renewable heat is a key strategic priority for meeting our binding renewable energy and carbon dioxide reduction targets. Ground energy systems, where heat stored in the ground is extracted using a ground source heat pump will therefore play a key role in future energy provision. Recently, innovations in foundation engineering have allowed various geo-structures to be equipped with heat transfer pipes to enable them to act heat exchangers as part of ground energy systems. Railway or metro tunnels and sewer tunnels in urban areas offer a particular advantage for use with ground energy systems. They both offer an additional source of heat within the ground, as well as important nearby end-users for the heat energy that can be extracted.

In the next two decades London could see the construction of over 150km of new rail and sewer tunnels beneath the capital. This offers an unparalleled opportunity to offer sustainable heating to parts of the city by using the lining of these tunnels as heat exchangers. As well as extracting useable heating energy this will have the additional benefit of cooling the rail tunnels. However, while small trial sections of so called “energy tunnels” have been constructed in Europe, there is no full scale operational experience and no experience at all within the UK.

This project will investigate the energy potential of London’s future tunnels. It will involve exploration of the heat available from train breaking and sewerage, laboratory scale experiments to determine appropriate thermal boundary conditions for the tunnel lining and subsequent numerical simulation of tunnel linings and the surrounding ground under thermal load. The project will be run in collaboration with industry to ensure buildability is taken into account as well as to consider construction costs and payback periods.

This project is currently unfunded. Please contact me if interested.

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