In conversation with Dr Karen Lythgoe, Research Fellow at the Earth Observatory of Singapore

1. What area of earth science do you study and monitor?

I am a seismologist at the Earth Observatory of Singapore at Nanyang Technological University, where I monitor and study earthquake hazards and sub-surface imaging both for the deep and the shallow earth. I apply seismology to important Earth science problems, including earthquake processes, Earth structure and dynamics, and smart city development.

2. What opportunities exist to capture heat from the deep earth to create low carbon energy and reduce the emission of greenhouse gases?

Recently there was an article in the Guardian about a group of geologists in New Zealand who are hoping to tap into a clean energy source by drilling deep into an extinct 11-million-year-old volcano on the South Island. They hope to harness energy stored in these old volcanic rocks to create geothermal heating.

Their idea is to pump water underground, where the water will get heated by the residual heat within the rocks and then it will circle back up to the surface and flow through buildings, providing heat during the colder months.

They are planning on drilling two wells, in order to gather enough data to test whether there is sufficient heat at depths below the surface to power a geothermal power plant. It is an interesting proposition to consider, as there is so much geothermal energy around the region in Southeast Asia where 90 per cent of the world’s volcanoes sit — often referred to as the ‘Ring of Fire’.

Knowing what is going on under the earth is critical to the planning of any future energy resource, but also to the health and safety of those in the region who could be at risk of a volcanic eruption.

3. Do you only find geothermal energy within volcanic structures?

We don’t just find geothermal energy at the site of a volcano. We also find it along geological fault lines — these are zones of weakness in the earth’s crust. That means they act as pathways for fluids to circulate. One such example is the Great Sumatran Fault, which we are currently monitoring for earthquake hazards. It also has hot springs along its fault line in several places.

We can use seismic imaging to see where the earthquakes are to understand it from a geohazards point of view, but we can also use this imaging to understand the geological system as a whole.

4. What are the key elements you need to have at a geological site to make it a viable heat source?

In addition to heat, to build a geothermal power plant you also need to have good water flow. This is critical so that a large amount of water can be pumped underground and back up to the surface to drive the geothermal heating system. This means that the rocks need to have some fractures in them so the water can flow through them. Old volcanoes may not be the best case for this scenario, as they are not expected to have many fractures that allow water to flow through.

One key consideration is that if you do harness geothermal energy from the earth, you have to be very cautious and monitor the fracture zones since there is a potential for this process to trigger small magnitude earthquakes. One extreme example of this is a few years ago in South Korea where a 5.4-magnitude earthquake happened close to a geothermal power plant. 

It was thought that this earthquake happened on a geological fault that was nearby and which was previously unidentified.

This is testimony to the importance of the work we do at the Earth Observatory of Singapore (EOS) in terms of identifying geological faults and monitoring seismicity, which are very critical to supporting the planning and location of geothermal energy stations in the future. Geothermal energy is a complex system: we need to have a heat source and we also need to have fractures in the rocks in order to have good water flow.

5. Is there any potential for future geothermal energy here in Singapore?

Here in Singapore we have hot springs, and, in the future, there are plans to drill approximately two kilometres below the surface in order to test how hot the water is and how fast the flow is at these depths. We expect the rocks to have some fractures, but we don’t know if there will be enough for the water to be able to flow through in sufficiently high volumes.

It will be remarkably interesting to see whether there is a potential for future geothermal energy in Singapore.

We know there is tremendous potential for geothermal energy in the rest of Southeast Asia. Over 40 per cent of the world’s estimated geothermal energy is found in Indonesia alone, so we do need to carefully consider and monitor these areas along with other seismically active areas such as New Zealand.

6. How does your work support the development of sustainable energy in the region?

The research that we do here at the EOS and the monitoring we do across the region help government and communities plan for future developments to ensure the safety and prosperity of those in Southeast Asia.

We also need to play a role in the energy transition and one part of that is understanding where and how we can safely harness the heat of the deep earth and to do that we need to understand these geological systems as a whole.

At EOS, we work with many countries across the region to increase their knowledge base, to help them better understand what is happening deep beneath the earth’s surface, enabling them to make informed decisions for a brighter and more sustainable future.

_{(Thumbnail source: Wikilimages from Pixabay)}