Residential and Commercial, Underground Thermal Energy Storage
LOCATION South West London
PRODUCT Boode Select Screen and Casing
The Riverlight scheme is a large residential project in south west London, overlooking the river Thames. A 2.9MW cooling and heating ATES system was installed for five mixed use buildings including over 200 luxury apartments, associated affordable apartments and commercial space. The completely reversible open loop ATES system comprises 8 wells, 4 warm and 4 cold, 130 metres deep and delivering a planned peak groundwater flow rate of 50m3/hr per well.
The well construction consisted of the drilling and installation of a Boode 330 x 292mm PVC casing through the Tertiary deposits of the London Basin to depths of approximately 70m to the water bearing chalk formation, below the challenging London Clay. The holes were started off c.450mm diameter and were drilled mud rotary reverse circulation to the top of the chalk. A mud program was implemented using Soda Ash as a water conditioner to reduce excess calcium & to maintain an optimum pH of 8.5 – 9.5 and to enhance yield, hydration & performance of the polymeric additives, plus a dry PHPA polymer for enhanced stabilization and inhibition of the water sensitive London Clay.
The PVC casing was then grouted in place using high quality pelletized bentonite grout. The hole was completed using R/C water flush techniques within the chalk aquifer to the completion depth ranging from 95-125m.
Conventionally, carbon steel casing is used at the ‘conductor’ stage as a support to the drilling operations, preventing soft formations near the surface from caving in and to conduct drilling mud from the bottom of the hole to the surface when drilling starts. However, steel casing is heavy, which can make access more difficult in the early stages of drilling and it must be either welded on site or threaded, requiring a heavy & therefore more expensive steel to be sourced.
IFTech, the contractors and installers of the ATES system chose Boode’s 330mm OD x 292mm, 19.5mm wall- thickness (heavy-wall) PVC Select casing. PVC is comparatively light, easing on-site handling, and can be supplied threaded or, as at Riverlight, with strong (2,072kN) solvent weld connections.
Boode is a market leader in the supply of approved PVC well casing and screen systems for the installation of Underground Thermal Energy Storage (UTES), also referred to as Aquifer Thermal Energy Storage (ATES). The systems were first installed in the Netherlands in the early 1980’s now growing in popularity. These renewable systems provide heating in winter and cooling in summer to buildings, through heat exchangers, via the extraction of groundwater from boreholes drilled into natural underground layers where the heat and cold are stored. The installed systems vary in depth from 30mtrs to 200mtrs plus in suitable geological formations, and can contribute to savings of up to 75% on current heating& cooling bills.
The advantages of installing these systems are:
- Renewable energy source
- Carbon emissions reduced by up to 60%
- Low risk proven technology
- Cost effective
- Payback achievable in less than 5 year