Steven Sewell

Steven Sewell

Job title


Who do you work for?

I work in the geothermal division of Mighty River Power, a New Zealand company that produces energy from renewable, sustainable energy resources. While the main energy resource we use is hydroelectric power, Mighty River Power is increasingly using geothermal energy. It also is exploring other renewable forms of energy. The company also is involved in geothermal energy projects in overseas countries such as Chile, USA and Germany. Its website is at

What does your job involve?

My job is quite multi-disciplinary, covering many areas of science and engineering. It mostly involves using physics-based methods to explore, develop and manage geothermal fields (regions that are suitable for generating geothermal power).

Geothermal energy involves circulating hot fluids (~150-300 °C) from regions below the surface (called the sub-surface) and using the hot fluids to turn turbines and generate electricity.

To access the hot fluids, wells are drilled into the ground up to 3-4 kilometres deep. Naturally we need ‘images’ of these regions before any drilling is done. We need to know things like what kinds of rocks are present, whether there are any faults in the rocks, the size and location of the reservoir of hot fluids, and their likely temperature. This enables us to work out where exploration wells should be drilled.

One of the main imaging methods used in geothermal energy is magnetotelluric (MT) surveys. In this kind of survey, the electric and magnetic fields present are measured. The data is then processed to produce a kind of map of the region below the surface. A big part of my job is to plan and manage the running of these surveys and process and interpret the data that comes from them.

What is the most rewarding part of your current job?

Probably the most rewarding aspect is going in to survey a possible new geothermal field. It is good to spend some time outdoors instead of staying in an office all the time.

What is the most challenging part of your current job?

Time management! I have a lot going on in a wide variety of areas and managing my time is hard. This is nothing unusual, though, for anyone in the geothermal business at the moment!

What do you hope to do in the future?

I would like to become an expert in geothermal energy and help to put as much geothermal energy on the electricity grid as I can.

What are some of the benefits of being a geoscientist?

Geoscientists generally are paid quite well and often have opportunities to travel with their job. After studying and initially working in Australia, I have been fortunate enough to travel overseas with work to Kyrgyzstan, India and now New Zealand. Geoscientists in Australia can have widely varying salaries. Those in the minerals and petroleum sectors tend to get paid quite well, but are exposed to the ups and downs of mineral and oil prices. Salaries can range from $50,000 to $100,000 and well over. Some of the people with whom I went to university who obtained jobs with mining companies were paid in excess of $100,000 straight out of university! People in geothermal energy are paid comparatively well, but not as much as those in the minerals and petroleum sectors.

Why is the study of science, technology or engineering relevant to your role?

Although my job title is ‘geophysicist’, the work I do day-to-day involves many areas of science and engineering. For example, the chemistry of the hot fluids can provide a vast amount of information on the nature of a particular geothermal reservoir. Engineering allows us to determine how the hot fluid will flow through the reservoir into the wells and afterward be used to generate electricity. My work is very cross-disciplinary, and geothermal geoscientists and engineers need to have a wide background in many areas of science and engineering.

What training did you have for this job?

After finishing High School in country New South Wales, I enrolled in a Bachelor of Engineering and Science at Monash University in Melbourne. I dropped out of the engineering part of my course in my first year, continuing on with my science degree, not really knowing exactly what I wanted to do. I then took courses in maths, physics and geology in my second and third years and found out about geophysics in my third year.

I did a third year project in geophysics looking at heat flow through the earth, which was my first introduction to geothermal energy. I followed that project up with similar work in my Honours (4th) year. After university I worked for Geoscience Australia for around 6 months then began working for a geothermal energy consultancy in Melbourne. I then took a post-graduate course in geothermal energy for six months at the University of Auckland. After I finished that course, I obtained my current job at Mighty River Power and have now moved to Rotorua.

What career advice would you give to school students interested in a similar career?

A career in geothermal energy as a geophysicist is best supported by having a background in maths, physics and geology, so you should study as much as you can in these areas at school and university.

If you don’t know at this stage what career path you would like to take, do not worry! By the end of my second year at university, I still had no idea what direction my career would take. My main piece of advice would be to always work hard regardless of whether or not you know where it is taking you, and to try to find something you are keenly interested in and passionate about doing. If you can do this, work will hardly seem like work at all!