Waste cleans waste
Waste cleans waste: spent solar panels to clean up legacy landfills
Lead Supervisor: Salvatore Grasso
Degree Programme: PhD in Materials Science, School of Engineering and Materials Science
Co-Supervisor:
Kate Spencer (Department of Geography and Environmental Science)
Project Description
Can retired solar panels clean up the waste we left behind, and who should pay? England and Wales hold an estimated 21,000 unregulated, pre permit legacy landfills, many on coastal margins, orphaned, with no liable party to fund clean up (POST, 2026). The people who live beside them inherit the risk: waste as a condition of life (Pillar 1) that needs socio technological interventions (Pillar 2). This PhD solves that problem with electricity. This project develops three field assisted regimes within Field Assisted Material Engineering (FAME), spanning the full thermal range these aged soils need, from gentle water based treatment to flash heating. You will test them on mixed waste materials from Prof Kate Spencer's Thames Estuary legacy landfill work, with field access explored where possible.
Regime 1, low temperature (below 100 degrees C): a water based electrochemical process combining electrokinetic transport with in situ mineralisation, extending flash cold sintering (Kermani, Grasso et al., 2020) to convert ionic contaminants into stable phases such as fluorapatite, avoiding the extraction burden of classical electrokinetic remediation.
Regime 2, intermediate temperature (below 1,000 degrees C): an unexplored regime using internal electrical discharge at particle contacts, drawing on field assisted sintering physics, where intensified current and cathodic electrolysis create hot, reducing micro environments that immobilise redox sensitive toxic elements. The most exploratory strand.
Regime 3, high temperature sublimation (above 1,000 degrees C): pulsed Joule heating to 1,000 to 3,000 degrees C within seconds (Deng et al., 2023), already about £33 per tonne, 69 percent below soil washing and 73 percent below chemical oxidation.
All three regimes are designed to run on recovered end of life photovoltaic panels, extending the PI's EPSRC/Defra Green Loop grant into a self contained, off grid unit. At about 420 kWh per tonne (Deng et al., 2023), every £0.10 per kWh adds £42 per tonne, so near zero cost power should cut cost further below £33 per tonne. A key output is a financing model and business case for remediation using this power, co developed with Prof Spencer's team and community stakeholders, closing legacy landfill's funding gap. You will design and run experiments across the three regimes, characterise the treated soils, and work with Prof Spencer's team on cost, governance and community perspectives. Explore open questions nobody has answered (Regime 2 is untried), a lab spanning cold sintering to 3,000 degrees C flash heating, supervisors from materials science and geography, and the Leverhulme cohort and Waste School.
What we're looking for in a student
(1) A strong first degree, typically 2:1 or above or equivalent, in materials science, chemical or environmental engineering, chemistry, physics, geoscience or a related discipline. No prior experience of electrical processing is needed. We welcome curiosity about waste, justice and working with geographers and communities, and any background in electrochemistry, ceramics, soils or analytical characterisation.
(2) You will have access to FAME's field assisted processing platform, materials characterisation (SEM, XRD, Raman), joint supervision from materials science and geography, the Waste School and cohort activities, and mixed waste materials and field context from Prof Spencer's Thames Estuary work.
Key words: Legacy landfills; socio technological interventions; spent solar panels; environmental justice; co production