THE GEOTHERMAL PROCESS

Geothermal drilling is the process of drilling into the Earth’s surface to access heat stored underground.

For Heating (Closed-Loop Systems):

• Boreholes are drilled 300–600 feet deep, sometimes deeper.
• Vertical closed loops of piping are inserted, typically in a U-shape.
• Filled with grout to improve thermal transfer and protect groundwater.

Residential geothermal drilling typically takes 1–3 days per borehole. Deep geothermal wells can take longer, depending on depth and conditions.

Geothermal grouting is the process of injecting a grout material into the borehole surrounding the geothermal loops or casing to improve heat transfer and prevent environmental contamination. The grout helps secure the geothermal pipes in place and enhances the thermal conductivity between the pipes and the surrounding soil or rock, ensuring that the geothermal system performs efficiently.

The primary goal of geothermal grouting is to create an efficient heat exchange between the geothermal pipes and the surrounding ground. The grout fills any gaps between the pipes and the surrounding rock or soil, allowing heat to transfer more effectively from the ground into the system. Better thermal conductivity means better performance for the geothermal system, ensuring it can extract or dissipate heat as needed.

Geothermal piping refers to the network of pipes used in a geothermal heat pump system to transfer heat between a building and the ground. This piping system forms the "loop" that circulates a heat transfer fluid (usually a water-glycol mixture) through the ground to absorb heat in winter or release heat in summer. Geothermal systems use the consistent temperature of the earth to provide energy-efficient heating and cooling.

The pipes in the loop are filled with a heat transfer fluid (usually a mixture of water and propylene glycol or ethylene glycol) to prevent freezing in cold temperatures and to improve heat transfer. The fluid circulates through the pipes, either absorbing heat from the ground in the winter or releasing heat into the ground in the summer.

Geothermal well testing is the process of evaluating a geothermal well to assess its productivity and performance, ensuring that it can meet the requirements of a geothermal energy system or project. The testing provides crucial data on the well's flow rates, temperature, pressure, and long-term sustainability, helping engineers design systems that are efficient and cost-effective.

A geothermal flush is a maintenance process used in geothermal heating and cooling systems. Geothermal systems rely on a heat pump to transfer heat between a building and the ground via a closed loop of pipes buried underground. Over time, the fluid circulating through the system can become contaminated with debris, scale, or bacteria, which can hinder the system's efficiency and performance. A geothermal flush is designed to clean and flush out these contaminants from the system to restore its efficiency.

The Role of Glycol in Geothermal Systems:
In many geothermal systems, the fluid circulating through the pipes is a mixture of water and glycol. Glycol is used in these systems for several important reasons:

• Freeze Protection: Glycol (usually propylene glycol or ethylene glycol) lowers the freezing point of the fluid mixture. This is crucial in colder climates, where the temperature of the fluid in the underground pipes could drop below freezing and cause damage to the system.
• Heat Transfer: Glycol has good thermal conductivity, which helps the system absorb and transfer heat more effectively. It ensures that the heat pump operates efficiently, whether in heating or cooling mode.
• Corrosion Prevention: Glycol can help prevent corrosion within the closed-loop system by providing a protective barrier for the pipes and other components.

How Glycol Is Involved in a Geothermal Flush:
When performing a geothermal flush, the goal is to clean the fluid and remove contaminants like sludge, biofilm, and scale buildup that may have accumulated in the system. During the flush:
The existing glycol mixture (along with any contaminants) is removed from the system.
A flushing agent or cleaner may be introduced into the loop to break down any buildup.

After the system is thoroughly flushed, a fresh glycol mixture is added to the loop to ensure optimal performance and freeze protection. The glycol mixture needs to be properly balanced, as too much glycol can reduce the heat transfer efficiency, and too little can risk freezing in colder temperatures.

Glycol plays a key role in geothermal systems by preventing freezing, aiding heat transfer, and protecting against corrosion. During a geothermal flush, the glycol mixture is typically replaced after cleaning the system to ensure optimal performance.