Ground-source heat pump bentonite-based grouting research: A review of literature on existing bentonite-based grouting information. Final report

Technical Report · Tue Sep 01 04:00:00 EDT 1998

OSTI ID:354860

Remund, C ^[1]

---

1. South Dakota Univ., Brookings, SD (United States). Mechanical Engineering Dept.

Ground source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), are an attractive high efficiency heating and cooling technology. The ground heat exchangers (GHXs) used with this type of equipment must be adequately sealed to protect the subsurface environment, while also providing good heat transfer. Especially with vertical-bore ground heat exchange systems, the heat exchanger wellbore must be grouted with a material that seals aquifers from contamination, while avoiding voids and maximizing heat transfer capabilities. Numerous types of grout materials are available for sealing the boreholes, the most common being bentonite-based and cement-based grouts. This report summarizes results of an extensive literature review of bentonite-based grout materials, applications, application techniques, and limitations. This literature review was performed as part of work aimed at developing new, better performing bentonite-based grout materials, grouting techniques, and information, especially as related to grout sealing and heat transfer properties. The work also helps better define when one type of grout should be used vs. another. This study has sought to summarize the various standards and practices that exist for the more common types of applications, so that a more logical set of practices, standards, and limitations may be developed specifically for geothermal heat exchanger sealing applications. Applications studied here include: Vertical bores for geothermal heat pump systems; Water well sealing; Abandoned well and borehole sealing; Ground water quality monitoring well sealing; and Waste repository and disposal well (including nuclear waste) sealing.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (United States); Northern Geothermal Support Center (United States); South Dakota Univ., Mechanical Engineering Dept., Brookings, SD (United States)
• Sponsoring Organization: Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 354860
• Report Number(s): EPRI-TR--111035
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
BENTONITE
GEOTHERMAL WELLS
GROUND SOURCE HEAT PUMPS
GROUTING
HEAT TRANSFER
PERFORMANCE
SEALING MATERIALS
SEALS