Enhancing the Circular Economy of Subsurface Green Energy Projects

The reality of climate change is something that governments across the world are having to come to terms with. It is imperative that greenhouse gas emissions are both reduced and offset to prevent global warming, with the aim of limiting temperature increases to a maximum of 1.5 degrees by the end of the century. In order to limit this global temperature rise, many countries have committed to achieving net zero emissions by 2050, which is to say that man-made greenhouse gas emissions are cut as close to zero as possible, while remaining emissions are removed naturally (such as by forests or oceans).
There are many different pathways needed to achieve this such as wind, solar, and carbon capture & storage (CCS), to name a few. The focus of this project is to look at the waste streams generated from subsurface green energy projects such as CCS, hydrogen storage, and geothermal. These projects generate large volumes of waste brines that need to be treated and disposed of. Due to the geochemical environment that these brines are formed in, they may contain technologically critical elements (TCEs) in solution such as lithium, cobalt, or rare earth metals, that are valuable in other green technologies such as batteries and solar cells. They may also contain high concentrations of toxic elements such as cadmium which require a higher degree of treatment to dispose of.
This project aims to address three different areas regarding subsurface green energy projects in the UK. The first is to analyse groundwater data currently available in the UK to understand where the geochemical conditions are best for the formation of TCE rich brines. Statistical analyses and geographic information systems (GIS) will be used to visualise the groundwater data that has been compiled. Secondly, it is important to understand the chemical composition of the brines that are already being produced by CCS clusters in the UK, and this will be done by analysing samples from four of the UK's CCS clusters. Techniques such as ion chromatography (IC), inductively coupled plasma optical emission spectroscopy (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS) will be used to determine the content of ions and metals in these brine samples. The final objective is to develop reusable sorbent materials that can extract TCEs from brines for future use, while also removing toxic elements to improve the treatment of brines before disposal to the environment or reuse in other industries.
By turning what is currently a waste product into a potential source of TCEs, this project aims to enhance the economic viability of subsurface green energy projects by tying them into the circular economy.
William Norfolk
Supervisors: Dr Shannon Flynn & Dr Mark Ireland