To make a difference in the energy transition, we have to make heat more sustainable.
Geothermal energy could account for 20 % of that. That holds great promise!
Published on 01 September 2020
Geothermal energy in the Dutch energy transition
Geothermal energy, the production of heat from deep underground, is a promising and sustainable alternative to heat from natural gas. The Netherlands has a huge need for sustainable heat. The prognosis is that geothermal energy can make a significant contribution to our future heat supply. But the road ahead is challenging, with many uncertainties. It’s a route that must be developed carefully, step by step.
Yvonne A’Campo, Head of the Geo-energy and Geohazards Group at Witteveen+Bos, is fascinated by geothermal energy. Both societally, given the contribution it can make to our future need for sustainable heat, and professionally. As a geologist, she is interested in that deep subsurface of the earth, and is keen to gain insights into both opportunities and risks.
‘We distinguish between two types of geothermal heat: soil energy and geothermal energy. Soil energy (up to 500 metres deep) uses the soil’s insulating capacity to store heat or cold. Geothermal energy is the extraction of hot water from strata deeper than 500 metres. Most geothermal systems are situated between 1,500 and 3,000 metres, and produce hot water at 70-100 degrees Celsius. The heat is transferred to the customer through a heat exchanger, for example greenhouse horticulture or a residential area, and the cooled water is pumped back into the rock to be reheated there. The earth itself is an infinite source of heat.’
Yvonne: ‘More than 40 per cent of the Netherlands’ total energy consumption is used to generate heat. Only 4 per cent of our heat production comes from renewable energy. So you have to make heat more sustainable if you want to make a difference in the energy transition. Geothermal energy is expected to account for 20 per cent of that. It has enormous promise.’ But we’re still a long way from that. The Netherlands currently has twenty geothermal heat installations. One generates around 15 MW, equivalent to the heat needed for 7,500 homes. The geothermal sector’s ambition is to have 175 geothermal heat installations a decade from now, and 700 by 2050.
Once the gas fields are closed, geothermal energy should be one of the sustainable alternatives among other energy sources. Here the knowledge gained from the exploration and exploitation of gas and oil fields can be reused. ‘After my studies I worked for an oil and gas company for some time, gaining valuable experience aboard a North Sea oil rig. Drilling for oil and gas is comparable to drilling for geothermal energy. A young industry like geothermal energy can learn a huge amount from this sector with over 70 years of experience.’
Yvonne emphasises a significant difference between fossil energy sources and geothermal energy. ‘Heat can’t be transported over long distances the way oil or gas can, so the heat must be generated where it’s needed. This requires a knowledge of both the subsurface and the above-ground heat system.
‘We have broad in-house expertise at Witteveen+Bos, letting us take an integrated view of the geothermal system. Our knowledge covers the potential of the deep subsurface, geothermal drilling, heat exchangers and heat pumps, but also other heat sources (such as biomass, residual heat or aquathermia), the heat grid, heat storage and the customer’s use of heat. This lets us advise on the best possible coupling of the underground heat source with the above-ground heat system. We have performed a whole range of potential scans for industry and government, where we created feasible opportunities with this integrated view.’
This infographic is part of one of the geothermal risk fact sheets, entitled ‘Well leaks and surface spills’.
This broad expertise is also a strength when it comes to providing independent advice on any effects on the environment and residents. Like any technology, geothermal energy involves risks, such as leakage to groundwater and earthquakes.
‘The pumped water is about nine times saltier than seawater, and may contain dissolved heavy metals and slightly radioactive elements, among other things. We have conducted a range of projects around this issue with our geohydrological and chemical specialists, including research into the environmental impact of corrosion inhibitors, and the design for groundwater monitoring in geothermal energy.’
Geothermal energy is also subject to the risk of earthquakes. Alongside colleagues from the Earthquakes and Dynamics group, Yvonne is working on developing a calculation model to quantify the consequences of any induced seismicity in geothermal projects. ‘Making the risk tangible will let stakeholders make more informed choices on mitigating and accepting this risk.’
Communication is vital when weighing up the safe and responsible use of opportunities for geothermal energy against an appropriate protection policy. ‘The Province of Gelderland has commissioned us to produce a series of thematic fact sheets so as to communicate the risks of geothermal energy transparently and comprehensibly.’