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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Studying at Cambridge

 

Eamonn Joyce

Opportunities for energy exchange with the ground

Eamonn Joyce

Opportunities for energy exchange with the ground

Ground source heat pumps can be used to extract heat from the ground to provide space and water heating.  Heat pumps take in heat at a certain temperature and release it at a higher temperature, using the same process as a refrigerator.  Fluid is circulated through pipes coupled with the ground and the heat pump then raises the temperature of the fluid via the compression cycle to supply hot water to the building as from a normal boiler.  This system can be reversed during warm weather to use the ground as a heat dump and cool buildings.

When planners and designers are considering alternative energy options there is a narrow window of opportunity for geothermal solutions and a general lack of information to support them.  I aim to encourage the development of this technology in my thesis by constructing a whole life cost matrix of the available closed loop systems and comparing this with conventional heating and cooling systems in buildings.  This will encompass grants and incentives, carbon emissions, and other associated drawbacks and benefits of geothermal energy.

Closed loop systems can be divided into two areas:
1. Boreholes and earth collectors near the surface
The basic idea here is to use boreholes or earth collectors to extract the stored energy of the ground and utilise it by means of suitable systems integrated into buildings.
2. Energy foundations
Foundations, such as piles, diaphragm walls, slabs, etc. are use to absorb thermal energy from the ground.  The principle is that energy is extracted from or sunk into the ground or ground water by means of a fluid filled pipe system incorporated in the foundations which are already needed for static structural reasons

The UK is particularly well suited for the utilization of energy exchange with the ground, due to its temperate climate and rainfall levels that ensure good conductivity and year round rain-fall recharge.  In Europe governments and engineers have done a relatively good job exploiting geothermal sources of energy.  This is not the case in the UK even though it is considered to be the most energy-efficient, environmentally clean and cost-effective space conditioning system available.
This morning I will present my work, highlight some conclusions to date and identify concerns for the future.