# Repurposing the Knutsford-1 borehole as a deep borehole heat exchanger with consideration of palaeoclimate corrections to heat flow in the Cheshire Basin

## TL;DR

This paper shows how correcting for past climate changes improves geothermal energy estimates from old boreholes like Knutsford-1, revealing untapped energy potential.

## Contribution

The study introduces palaeoclimate corrections to heat flow assessments in legacy boreholes, revealing higher thermal yields and better geothermal resource estimates.

## Key findings

- Corrected heat flows (52 mW/m2) are higher than uncorrected values (46 mW/m2) at Knutsford-1.
- Temperature predictions using corrected heat flow align better with recorded data in a conductive model.
- DBHE simulations show a minimum 17 kW increase in thermal yield over 25 years with corrections.

## Abstract

Subsurface thermal data from UK boreholes typically lack palaeoclimatic corrections, leading to underestimations in heat flow. This can significantly affect predicted geothermal resources and system performance, creating a false perception of energy limitations. This study evaluates the impact of palaeoclimate corrections on geothermal performance in an onshore setting; focusing on the potential for a well to be re-entered and repurposed as a deep borehole heat exchanger (DBHE). Using the Knutsford-1 borehole, this re-evaluation for palaeoclimatic impacts on heat flow shows that corrected heat flows (52 mW/m2) exceed uncorrected values (46 mW/m2). In a steady state conductive model, temperature predictions based on the corrected heat flow align more closely to the recorded temperature data. Moreover, transient DBHE simulations using OpenGeoSys software over 25 years reveal a minimum 17 kW increase in thermal yield, highlighting the operational implications and benefits of these corrections. With thousands of legacy boreholes worldwide, integrating palaeoclimate corrections into geothermal assessments could reveal substantial untapped energy potential. By unlocking previously overlooked geothermal potential, this research highlights how accurate subsurface (re)assessments can transform legacy infrastructure into a cost-effective, sustainable energy source – demonstrating that with better data and a more holistic approach, existing wells can support low-carbon heat production.