How long do geothermal boreholes typically last?

Over the past five years or so, there has been an explosion of interest in geothermal energy solutions. While they are highly efficient and easy to run, one of the main points of hesitation is often related to their steep initial investment costs. 

Here, we take a look at what kind of timeframe you can expect that investment to continue to pay out over, but looking at the expected lifespan of a typical geothermal borehole.

The importance of longevity

Geothermal boreholes are often great energy investments, but they can also require a substantial amount of capital to get them set up, with the borehole being the most expensive part. 

As a result, it’s natural to wonder how long the system will last for, to try to calculate a timeline over which the system will keep paying for itself. 

Whether you’re a homeowner hoping to save on energy bills over the coming decades, or an investor trying to decide whether a business you’re a stakeholder in is making an appropriate request for additional funds, it helps to have some basic idea as to how these systems work.

The borehole itself

The actual borehole is one of the longest lasting parts in a geothermal energy system. The borehole and the loop that’s installed inside it can easily last between 50 and 100 years, over which time you’ll likely go through a number of upgrades in the parts of the system that sit above ground. 

One of the main reasons the borehole can last for so long is the simplicity of the system. The borehole and loop have no moving parts – it’s essentially just a big, strong loop of durable plastic piping that’s buried in the ground. 

How to ensure longevity

There are a few things that will need to be taken care of to ensure maximum longevity. 

Installation

For a borehole to last 50 or even 100 years, it has to be designed and installed properly, and be made from the right materials. The well needs to be drilled in a stable location, and the casing needs to be made from the right materials and fixed using the appropriate cements and grouting.

Other factors, such as the water chemistry of the borehole and geological shifts, can also have an impact on the longevity of the system. Some of these risks can be predicted and mitigated; others may be less controllable.

Maintenance

There are also some maintenance-related considerations that can have a positive impact on borehole longevity, and on how long the other parts of the system will last. You will need to use chemicals to remove scale and other mineral buildups, clean pumps, and monitor the chemistry of the borehole. 

If installed and looked after properly, then it’s likely that your geothermal borehole will outlive you. You will need to replace other parts of the system at more regular intervals, but the most expensive part of your investment will remain effective for a long, long time to come.