A semi-quantitative technique for mapping potential aquifer productivity on the national scale: example of England and Wales (UK)

The development and validation of aquifer productivity and depth-to-source maps for England and Wales are described. Aquifer productivity maps can provide valuable support for the assessment, planning and management of groundwater and renewable heat energy resources. Aquifer productivity is often mapped using geostatistical interpolation techniques such as kriging, but these techniques tend to be unsuitable for mapping at the national scale due to the high data (and time) demands. A methodology is outlined for mapping aquifer productivity at the national scale using existing national-scale data sets. Pumping test data are used to characterise the potential borehole yields that different geological formations of varying lithologies and ages can provide. Based on this analysis and using expert knowledge, the corresponding map codes on the geological map are assigned to potential productivity classes. The subsurface (concealed) extent of aquifer units is mapped from geophysical data, and together with the attributed geological map, provide the bedrock-aquifer productivity map. Drilling and pumping costs can be an important consideration when evaluating the feasibility of developing a groundwater source. Thus, a map of the approximate depth to source is developed alongside the aquifer productivity map. The maps are validated using independent data sets, and map performance is compared against performance from maps derived by random and uniform attribution. The results show that the maps successfully predict potential productivity and approximate depth to the water source, although utility of the depth-to-source map could be improved by increasing the vertical discretisation at which depth intervals are mapped

Mapping suitability for open-loop ground source heat pump systems: a screening tool for England and Wales, UK

The UK Government expects that, by 2020, 12% of the UK’s heat demand will come from renewable sources, and is providing incentives to help achieve this. Open-loop ground source heat pumps (GSHP) could make a substantial contribution. A web-based screening tool has been developed that highlights areas where conditions may be suitable for installing commercial-scale (>100 kW heating or cooling demand) open-loop GSHP systems in England and Wales. In addition to the basic requirements for open-loop GSHP (i.e. the availability of a sufficiently productive aquifer within a reasonable depth beneath the surface) the tool provides information on existing abstractions, water chemistry and the location of protected areas. Validation and tool application show that it produces reliable results and provides an effective method for the initial assessment of subsurface conditions and suitability for GSHP installations. Hence, the tool can help to reduce uncertainty at the early planning stage, and also to promote GSHP technology to a variety of audiences

Open-loop ground source heat pumps and groundwater systems : a literature review of current applications, regulations and problems

This report presents a literature study that was carried out to collect data and information required for developing a strategy to assess the suitability and sustainability of UK aquifers for (open-loop) GSHP installations. Developing such a strategy requires a good hydrogeological understanding but also a good knowledge of what GSHP systems are currently in use, how they are used, what problems are associated with their use and how they are regulated. Once this is understood, a methodology can be devised that assesses the suitability of an aquifer/location for GSHP installations and considers its sustainable use. Considering the complexity of influencing factors and processes, this is likely to include the use of numerical models and/or data management tools, such as GIS. This report collects and summarizes the information available in the contemporary literature on open-loop ground source heat pump (GSHP) applications. Chapter 1 provides a brief introduction and background information on the subject. In Chapter 2, information on the general use of open-loop GSHP technology within the UK are gathered together with statistics on the number of installations and capacities. Chapter 3 gives specific examples of schemes that are currently in operation in the UK and worldwide. Where available, this includes system-specific data such as abstraction rates, thermal capacities and information on the system’s design. Chapter 4 summarizes available information and data on the costeffectiveness of GSHP installations while Chapter 5 discusses potential problems associated with the running of such schemes. Chapter 6 is concerned with the regulation of GSHP systems. It gives a brief outline of existing regulatory approaches as currently employed within different European countries as well as the US. Finally Chapter 7 examines existing modelling approaches that have been used to investigate how GSHP schemes impact on the source aquifer. The chapter also reviews GIS-based tools that evaluate the suitability and sustainability of an aquifer for GSHP installations

Combined impacts of future land-use and climate stressors on water resources and quality in groundwater and surface waterbodies of the upper Thames river basin, UK

It is widely acknowledged that waterbodies are becoming increasingly affected by a wide range of drivers of change arising from human activity. To illustrate how this can be quantified a linked modelling approach was applied in the Thames river basin in southern UK. Changes to river flows, water temperature, river and reservoir quality were predicted under three contrasting future “storylines”; one an extension of present day rates of economic development, the others representing more extreme and less sustainable visions. Modelling revealed that lower baseflow conditions will arise under all storylines. For the less extreme storyline river water quality is likely to deteriorate but reservoir quality will improve slightly. The two more extreme futures could not be supported by current management strategies to meet water demand. To satisfy these scenarios, transfer of river water from outside the Thames river basin would be necessary. Consequently, some improvement over present day water quality in the river may be seen, and for most indicators conditions would be better than in the less extreme storyline. However, because phosphorus concentrations will rise, the invoked changes in water demand management would not be of a form suitable to prevent a marked deterioration in reservoir water quality

Geothermal Energy Challenge Fund: the Guardbridge Geothermal Technology Project

GEOTHERMAL ENERGY CHALLENGE EXECUTIVE SUMMARY This feasibility study investigates whether a geothermal district heating system, which accesses Hot Sedimentary Aquifer (HSA) resources underlying a brownfield site at Guardbridge in northeast Fife, can be developed in a cost-effective manner. This project’s scope is to assess the available geological information and estimate the hot saline aquifer heat supply, calculate the current heat demand at the Guardbridge site, Guardbridge village, and the nearby towns of Leuchars and Balmullo, and to incorporate future Guardbridge development plans (provided by the University of St Andrews) and anticipated growth in housing stock (from Fife Council) to estimate future heat demand. The capital, maintenance and repair costs for the geothermal well and designed district heating network are used to develop economic models for a number of district heat network scenarios. A key aspect of this study is an evaluation of the opportunities to cost effectively de-risk deep geothermal exploration in Central Scotland, and to outline the potential for developing geological heat storage systems. The study identifies the key legislative and environmental issues, risks and uncertainties associated with any exploration and production, involves stakeholder engagement, and makes recommendations for a Phase 2 stage for geothermal heat development at Guardbridge. Two of the key outputs from this feasibility study will be an economic model and business case based on different heat demand options, and an optimised model of well design based on different exploration strategies. Both are transferable to similar operations at other geothermal sites. The key objectives are therefore to: (a)design a geothermal well that will be drilled in Phase 2 of the project, and secure valuable information on Fife regional sub-surface geology and geothermal properties of the primary aquifer, (b)explore how advanced drilling techniques, such as directional drilling, can be deployed to improve geothermal recovery, (c) demonstrate how a geothermal system can integrate with an existing biomass heating installation to optimise both schemes and provide a district heat network for on-site industries and the local community, (d)evaluate the potential for storage of seasonal heat energy in the subsurface (a first in Scotland), and (e)assess the relative merits of water treatment and on-site recycling, reinjection or disposal to sea. A regional geological model was constructed using available data from the British Geological Survey, published data and academic theses. The sub-surface geology was interpreted from surface geology and extrapolating the local behaviour of geological structures into the Guardbridge area. Modelling the geology involved defining the orientation and width of a natural fault zone, which could be a significant influence on the behaviour of the Hot Sedimentary Aquifers. The rock units of interest in this study are the Upper Devonian Scone Sandstone, Glenvale Sandstone, Knox Pulpit and Kinnesswood formations, and the latter two units are previously identified as having the highest potential to be highly productive aquifers. The presence of a major fault near the Guardbridge site means that the target aquifers are at very different depths on either side of the fault. The report therefore investigates and evaluates three well options to target the different aquifers at the varying depths on either side of the fault. Hydrogeological modelling was conducted using FEFLOW® to evaluate the behaviour of the fault on fluid flow rates, and to predict the necessary conductivities to produce reasonable, economic and sustainable rates of fluid extraction. Although not an accurate model of the Guardbridge site, and limited by a significant lack of data constraining the important parameters, the flow simulations suggest that fracture permeability in the aquifers and underlying rocks is needed to sustain the flows recommended by this study, and re-injection would be required if a producing well was to be sustainable over many decades. Regionally developed rock quality predictors have been used to estimate the permeability and temperature of the target aquifer intervals in the three selected well options at, or near, Guardbridge. Oil field well simulation tools have been used to estimate water flow rates, temperature profiles, and circulating rates from different geological models of the wells. Two of the wells, GB-1 and ES-1, are not expected to penetrate enough high permeability sandstone to support the minimum water flow rates of 5 l/s and so are ruled out as viable aquifer producers. GB-2 is a deviated well that penetrates the Kinnesswood and Knox Pulpit formations, the best quality regional aquifers, in a zone where the fault may enhance the permeability even more, and has potential to supply 5 to 20 l/s of water at a surface temperature of 25 oC (± 2 oC). Such a well will be produced using an electric submersible pump which will require 20 - 40 kw of power to deliver 15 l/s of flow (although the volumetric rate will vary with the rock quality). GB-2 is taken forward and drilling designs are provided with three outcomes: 1) a dry hole scenario; 2) a 5 l/s scenario; and, 3) a 15 l/s scenario. The vertical wells have been modelled as heat pump circulating wells, and therefore would not produce any aquifer water at the surface. Only deeper wells, up to 2500 m, have the potential to give surface temperature increase of 5 oC at reasonable circulation rates (e.g. 8 l/s). A deep GB-1 well as a heat pump could be taken forward in Phase 2 as an alternative heat source. The proposed GB-2 deviated well can be drilled across the fault from the Guardbridge site to a depth of 1200 m. A casing string set will isolate the shallow geology and a slotted liner used to prevent hole collapse of the target intervals. Such a well will require a 100 tonne conventional drilling rig and well control, logging and coring tools will assess the aquifer quality. In the most likely case, the drilling phase will take 24 days, including rig mobilisation and demobilisation. If coring and logging demonstrate that the well will not flow adequately, then the well will be suspended. Low cost options have been investigated that would allow exploratory wells to be drilled and this could result in the recovery of regionally significant data on the performance of the aquifers at depth, although none of the boreholes could be completed to production stage due the drilling technology employed. The drilling scenarios investigated do not include a re-injection well, in order to create an economically viable district heating network project, even though very preliminary hydrogeological modelling demonstrates that re-injection is required if the geothermal well is to be sustainable over 30+ years. Alternative management of produced water investigated in this report are: water disposal-tosea and partial-full water recycling and re-use on site. The first option could have environmental consequences on the adjacent Eden Estuary, which is part of the Tay River and Eden Estuary Special Protection Area, and these potential impacts would need formal assessment by a competent authority (Fife Council and SNH) as part of a Habitat Regulations Appraisal, and an Environmental Impact Assessment is most likely required. The second option reduces the environmental impacts on the estuary, but has additional CAPEX and OPEX costs which are estimated. The opportunity to be innovative about partial water recycling and resale should be investigated in Phase 2. The heat demand is based on preliminary district heating network layouts at different scales, based on the demand analysis. Demand has been assessed at Guardbridge and the nearby towns of Leuchars and Balmullo, using the Scotland Heat Map and future development data provided by the University of St Andrews and the Fife Development Plan. These various options provide an indication of the potential annual and peak heating demands that can then be compared against the geothermal heating potential, and an economic modelling tool was developed to analyse the performance of the overall system, including key performance indicators to evaluate the financial viability. This analysis leads to a preliminary network design and an economic model of the potential scheme. The District Heating Opportunity Assessment Tool (DHOAT) designed for the Danish Energy Agency analyses the Heat Map data and preliminary network designs and provides peak and annual demands and key performance indicators, namely total heat demand and indicative CAPEX, OPEX, REPEX and heat sales. All input parameters are modelled with an uncertainty of ±10%. Based on this analysis, the proposed development of one well and estimated heat supply is not sufficient capacity to provide heat outside of the Guardbridge site itself. All district heating network designs and economic models were therefore based on the aggregated customer base of the Guardbridge site. The economic model assumes that geothermal heat can supply 50% of the Guardbridge site needs (2,867 MWh/a), with a capacity of 0.42 MW, and the other 50% would be provided by the biomass plant. Revenues from heat sales are based on a heat sale price scaling (MWh and p/kWh) and costs of heat from the biomass plant. An Excel model calculates the profitability of the scheme based on a CAPEX of £530,000 for the heating network and £1,517,000 for the well completion, flow tests and water treatment. OPEX and REPEX costs are principally power consumption for the heat and distribution pumps (£280,000), and a ESP and heat pump replacement after 10 years (£250,000). NPV and IRR are used to demonstrate viability for potential investors over a 21-year period; the best case scenario shows that the scheme might achieve a 10% IRR and a positive NPV. However, the heat sale price is too low to create sufficient margin to make the economic performance attractive. This is principally due to the cost of the geothermal heat. The capital cost of the geothermal well is a significant portion of the project CAPEX and does not vary with the well heat potential, which is a relatively modest value given the temperature and flow rate estimates presented. Flow rate is highly uncertain, while temperature is better constrained and low due to the shallow depth of the proposed well. The district heating network requires higher temperatures and the addition of a heat pump increases the capital costs and adds a relatively high operating cost for the electricity to run the pump. The carbon emissions reductions are compared to an individual gas boiler alternative (business as usual [BAU]) and the geothermal-biomass heat network shows an 84% reduction in carbon emissions, assuming that the biomass boilers and geothermal heat pumps each supply 50% of the network demand. About 58% of the emissions reduction (13,878 tonnes CO2/kWh relative to BAU) is attributed to heat generation from the biomass plant and the remaining 42% (9,812 tonnes CO2/kWh relative to BAU) is attributed to the geothermal well and the heat pump. These figures are based on a model lifetime of 20 years. The value of this carbon saving has not been included in the economic model, however it could be considered to represent an additional savings compared to the business-as-usual alternative. The heating network can be enhanced at a subsequent stage to provide combined heating and cooling for the site. This would increase the utilisation of the heat pump by operating in combined heating and cooling mode during interseasonal periods. Although not explored in any extensive technical or economic sense, the system could also potentially be used to fill separate hot and cold seasonal heat stores. Requirements for Phase 2 would begin with a non-invasive geophysical survey to provide imaging of the fault and the target aquifers in the subsurface. This could be completed in three months. Phase 2 would most likely require the preparation of an Environmental Statement before any drilling could commence on site, particularly addressing the viability of disposal of water to the sea. However, current developments at Guardbridge have required Environmental Statements (i.e. since 2014) and much baseline data already exists. The time required to complete an EIA range from 12 weeks to prepare the report, or up to one year of time if SNH and Fife Council require additional new data. A benefit of the Guardbridge site is therefore its status as an industrial site with a pre-existing history in terms of Environmental Statements. Ideally, Phase 2 would culminate in revised well designs, procurement of the drilling rig, and test drilling to intercept the fault and target aquifers. The time and costs are estimated and depend on the choice of drilling option. A positive outcome from a test borehole would lead to the design of a full production well and progression of the project as a Technology Demonstrator. Regardless of whether the test borehole proves that the Guardbridge District Heating Network project is viable, the data recovered as part of the test drilling (core samples, flow tests and water chemistry) will be highly significant for de-risking hot sedimentary aquifer exploration across central Scotland. The economic feasibility of the Guardbridge geothermal heat project is dependent on the best case scenario for flow rates, along with a large number of other poorly constrained variables. It could be economic, but there is a very large uncertainty in the geothermal heat estimates. However, the additional value in the potential research that can be achieved at Guardbridge in de-risking hot sedimentary aquifer exploration in the Central Belt of Scotland, as well as integrating low carbon heat source exploration with other technologies, including dual heating and cooling and water recycling, should be considered when deciding to progress this project

Visual and audio scene classification for detecting discrepancies in video: a baseline method and experimental protocol

This paper presents a baseline approach and an experimental protocol for a specific content verification problem: detecting discrepancies between the audio and video modalities in multimedia content. We first design and optimize an audio-visual scene classifier, to compare with existing classification baselines that use both modalities. Then, by applying this classifier separately to the audio and the visual modality, we can detect scene-class inconsistencies between them. To facilitate further research and provide a common evaluation platform, we introduce an experimental protocol and a benchmark dataset simulating such inconsistencies. Our approach achieves state-of-the-art results in scene classification and promising outcomes in audio-visual discrepancies detection, highlighting its potential in content verification applications.Comment: Accepted for publication, 3rd ACM Int. Workshop on Multimedia AI against Disinformation (MAD'24) at ACM ICMR'24, June 10, 2024, Phuket, Thailand. This is the "accepted version

Unlocking the potential of geothermal energy in the UK

This report is intended to provide technical information that complement the BGS Science Briefing Note: Deep impact: Unlocking the potential of geothermal energy for affordable low-carbon heating in the UK [1]. It gives a general overview of the deep geothermal opportunities that exist in the UK (although regional geothermal potential is not discussed here) as well as of financial, policy and regulatory actions that are needed to support the effective development and exploitation of deep geothermal resources in the UK. The recommendations are applicable to the UK government and its departments as well as to devolved administrations in Scotland, Northern Ireland and Wales, and devolved policy areas, such as heat policy and planning, in the respective nations. Following the introduction, the report is organised in three sections. In Section 1, details are given of the UK’s deep geothermal resources and how and where they could be utilised. Section 2 focuses on the experiences of continental Europe and the policies that have enabled the growth of a geothermal industry. Section 3 considers key policies and regulatory actions identified as necessary to drive the development of the UK geothermal sector from its current status of infancy to a mature technology that is universally recognised and utilised by a wide range of stakeholders, end-users and supported by investors

Geothermal Technologies : analysis of written evidence from the Environmental Audit Committee inquiry

In July 2022, The UK Parliament’s Environmental Audit Commission (EAC) launched an inquiry on geothermal technologies as part of their Technological Innovations and Climate Change inquiry (https://committees.parliament.uk/work/6777/technological-innovations-and-climatechange- geothermal-technologies/publications/). The inquiry focussed on Enhanced Geothermal Systems and Mine Water Energy Systems. It investigated the potential scale of their deployment in the UK to provide heat and power; the role geothermal technologies could have in the UK’s Energy Strategy and what barriers there are to the deployment, economic impact, and environmental impact of these technologies. As part of the inquiry, the EAC issued a call for the submission of written evidence to provide answers to one or more of the following questions: 1. What role can geothermal technologies take in the transition to net zero in the UK? 2. What barriers (technological, regulatory, or otherwise) are there to deploying operational geothermal technologies in the UK? 3. What is the scale of the potential market for geothermal energy sources and which geographic or other geological types are most suitable for exploitation of this natural resource? 4. Are current government support schemes sufficient to grow geothermal energy deployment in the UK? 5. What environmental concerns are associated with geothermal technologies, and are they appropriately accounted for in regulations? 6. What risks are there to investors, operators, and consumers of geothermal energy? How can these be mitigated? 7. How does the density of mine water systems affect their efficiency? Could widespread uptake of geothermal systems in dense population centres lead to a reduction in their ability to provide heat? 8. What economic impact could the deployment of mine water geothermal systems have on the areas in which they are deployed? The written evidence received by the EAC for this inquiry is published on the UK Parliament website at https://committees.parliament.uk/work/6777/technological-innovations-and-climatechange- geothermal-technologies/publications/written-evidence/. This report captures a qualitative analysis of this evidence. It specifically investigates what opportunities, challenges and barriers are identified by the submissions as well as the support measures that are suggested for developing a geothermal industry in the UK

Nested shallow geothermal systems

The long-term sustainability of shallow geothermal systems in dense urbanized areas can be potentially compromised by the existence of thermal interfaces. Thermal interferences between systems have to be avoided to prevent the loss of system performance. Nevertheless, in this work we provide evidence of a positive feedback from thermal interferences in certain controlled situations. Two real groundwater heat pump systems were investigated using real exploitation data sets to estimate the thermal energy demand bias and, by extrapolation, to assess the nature of thermal interferences between the systems. To do that, thermal interferences were modelled by means of a calibrated and validated 3D city-scale numerical model reproducing groundwater flow and heat transport. Results obtained showed a 39% (522 MWh·yr-1) energy imbalance towards cooling for one of the systems, which generated a hot thermal plume towards the downgradient and second system investigated. The nested system in the hot thermal plume only used groundwater for heating, thus establishing a positive symbiotic relationship between them. Considering the energy balance of both systems together, a reduced 9% imbalance was found, hence ensuring the long-term sustainability and renewability of the shallow geothermal resource exploited. The nested geothermal systems described illustrate the possibilities of a new management strategy in shallow geothermal energy governance