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Hot topic: Drilling spotlight

Choosing suitable drilling contractors for ground source energy work is vital, says Magpie Environmental Drilling Services contracts manager Michael Moggeridge.

With strict CO2 reduction targets and unstable energy supplies, green technologies are currently at the forefront of most new developments and social housing renovation projects.

Using the many renewable energy technologies available to the market is recognised as one of the most cost effective and reliable ways to achieve sustainability targets. The problem faced by the construction community is working out ways to gain a better understanding of this technology to avoid the pitfalls.

Gold rush technology

Ground source energy, which can deliver a few kilowatts of energy or multiple megawatts, is at the forefront of renewable energy sources. The system allows for energy to be collected from the ground in the form of heating and via a vertical ground loop typically 100m to 150m deep, known as a closed loop system. Alternatively energy can be collected via groundwater wells installed in pairs. This is known as an open loop system. The system relies on a fluid (predominantly water or water with additives in closed loop systems) being circulated into the ground via the ground loop and then passed through a heat pump which, for every 1kW of electrical energy it consumes, will deliver approximately 4kW of heating energy.

“This technology has been widely accepted across Europe and the United States. But the UK has been slow to accept and implement it.”

This technology has been widely accepted across Europe and the United States with Sweden installing over 100,000 heat pumps per year. But the UK has been slow to accept and implement it until recently. The market is now going through a gold rush moment with every man and his green dog jumping aboard the sustainable energy wagon and offering everything from expert design advice that promises to deliver the earth to drilling services from inexperienced companies which have seen the opportunity but cannot deliver a professional service.

Principal contractors and the end client need to align themselves at the earliest possible stage with expert and reliable drilling companies, designers and heat pump installers with proven track records. This will enable the team to deliver a well designed and installed system that is sustainable and cost effective.

Experience is vital

The installation process on site is key and what principal contractors must realise is that normal project management teams are unlikely to have had dealings with ground source energy drilling projects before.

“Drilling with airflush methods is slightly cheaper, but almost always does not allow control of the arisings coming out of the borehole, which leads to flooding.”

The drilling method is fundamental on sites where space is at a premium. Keeping sites free of standing water is a key requirement. Drilling with airflush methods is slightly cheaper, but almost always does not allow control of the arisings coming out of the borehole, which leads to sites and foundations being flooded and has been known to pebble dash the sides of any adjacent buildings or structures. Using a drilling contractor who is experienced with mud flush techniques is vital. Mud flush techniques involve pumping the arisings through settling tanks in a controlled manner without inundating the site with spoil.

The UK construction industry must be aware that the only way of keeping pace and avoiding the pitfalls with this fast growing market is to understand the processes involved from design to the delivery of these systems and to team up with reputable contractors and designers whose interests lie not only in the immediate future of their bank balance but in the long term future of this bright and sustainable technology.

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