Professor Ernst Huenges
Professor Ernst Huenges holds degrees in physics and geology. He is head of the International Centre for Geothermal Research at the Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences in Germany and lecturer on geothermal energy systems at the Technical University of Berlin. His research focuses on safe and efficient geothermal technologies to make geothermal a reliable component of the future energy mix.
What are the main geothermal energy technologies, and which of these technologies has the greatest potential on the European market?
Geothermal energy technologies depend on the specific geological setting. We have hot water bearing horizons in many parts of Europe. We call them hydrothermal reservoirs. In addition, the ground all across Europe has increasing temperature with depths. The horizons which do not bear water are called petrothermal systems. A general technology to economically exploit these reservoirs is to follow the so called concept of Enhanced (or Engineered) Geothermal Systems (EGS). The EGS concept includes artificial improvement of the hydraulic performance of a reservoir with the goal of using it as a source for the economic supply of heat or electric energy. The enhancement challenge involves the use of several non-conventional methods for exploring, developing and exploiting geothermal resources that are not considered economically viable with the use of conventional methods.
What is the current contribution of geothermal to the EU energy mix and how is this share expected to change in the medium to long term?
The current contribution is still very small compared to the huge existing potential. In the medium term a significant increase in geothermal heat supply can be expected, with a significant increase in geothermal power production in the long term. In the past we observed an increase in capacity of one order of magnitude in 20 years. With investment in research and development we have the chance to accelerate the deployment of geothermal technologies. However, it is important to note that a project with deep drill holes takes several years to implement and therefore the learning curve cannot be as steep as with other technologies, such as solar and wind, for example.
What technical obstacles currently hinder the scaling up of geothermal energy? What are the research priorities to overcome these obstacles?
There are still research challenges that need to be addressed in geothermal exploration and reservoir engineering and also in the monitoring and reliable operation of geothermal plants. Let’s take reservoir engineering, for example: if we succeed in increasing the productivity per well, then we can achieve a significant reduction in the specific costs of energy supply.
Is there potential to enhance geothermal output from resources that have already been identified / utilised? How does current research support this?
We have to invest further in EGS-technologies, because this enables the access to most of the European geothermal reservoirs. We learn most from operational projects. Therefore, increased investment in demonstrating the new methods would help a lot. We need several demonstration sites and each site requires investment in the order of EUR 10-30 million. Once we have these demonstrators in Europe, companies will be able to follow best practise and prepare for an extended market penetration. In addition, Europe will be able to retain its current technological lead in geothermal research.
Is the existing energy infrastructure ready to accommodate an increase in geothermal energy? How can the energy system be adapted to ensure that geothermal reaches its full potential?
There are no special requirements to accommodate electricity from geothermal plants into the grid. However, adapting district heating to low temperature would significantly increase the demand potential for geothermal heat, similar to solar heat. Nowadays, district heating systems are usually fired with fossil fuel, allowing temperatures above 100 or 130 °C. For these temperatures we would have to drill much deeper than necessary because only temperatures of about 60 °C are required for heating purposes. To take advantage of lower temperatures, we need heat transfer stations with larger areas in order to get the same amount of heat to the customer.
How does geothermal compare with other technologies in terms of levelised cost of electricity (LCOE)? Is there a cost target that the sector is aiming to achieve?
The LCOE of geothermal power depends on the site and specifically on the geological setting. For example, you don’t need to drill as deeply for geothermal energy in volcanic areas as in other regions. The LCOE of geothermal heat depends more on the size of the plant. Above a threshold of scale geothermal plants become competitive with any other source of heat supply.
Is enough being done to increase awareness among decision makers and the public regarding geothermal energy? What other non-technical barriers exist and what needs to be done to overcome them? What role does the SET-Plan play in this process?
We are seeing a significant improvement in the visibility of the geothermal option within the context of the future environmentally friendly energy mix. The SET-Plan and the involvement of industry are crucial for a broader deployment of geothermal plants. As with almost all new technologies, there is a public debate about the environmental risks associated with geothermal energy production. Dialog with the public requires the participation of all actors in the geothermal chain, with the provision of fundamental explanations of all the processes involved and a clear assessment of the risks. Political support is needed in setting the right framework conditions, for example in the mining regulatory process, and in the form of incentives to accelerate market penetration.