Sander Visser, Matthijs Noordhoek and Arianne Woudstra, students of the Hanzehogeschool Groningen, developed a Sustainable Transformed Energy Plant: a new use for exhausted gas extraction sites. Their master thesis, carried out for Royal HaskoningDHV, won the trio the GasTerra Energizer Award. A month later, Bert Loonstra and Christiaan Hoetz of Royal HaskoningDHV tell us what happened after the students won this innovation prize.
"The Netherlands has approximately 4000 gas wells. Many of these wells are still in use, but many others have or will become obsolete in the future. It is a shame to completely write off these wells. This is the reason why we had been toying with this idea for a while, but together with Sander, Matthijs and Arianne, we had the opportunity to actually examine the possibilities", says Bert Loonstra, Environmental consultant at Royal HaskoningDHV, enthusiastically.
No risk of earthquakes
Christiaan Hoetz, Consultant deep soil at HaskoningDHV, adds: "Old gas extraction sites get a new purpose as geothermal energy generation sites. A gas well consists of two concentric pipes. First, you disconnect the well at a depth of 3000 to 4000 meters. When injecting water through the outer pipe, it will slowly heat up on its way down. At a depth of 3000 meters, the temperature is approximately one hundred degrees Celcius. The water then flows back up through the inner pipe. This warm water can be used for example for glasshouse horticulture, to heat houses or to generate biogas in a fermentation facility. This technology enables us to circulate approximately ten cubic meters of water per hour, with a temperature of about 60 degrees when it comes aboveground. The energy efficiency of this technology is lower than for other deep-geothermal systems, but the investment costs are far lower. In addition, the technology produces sustainable energy and there is no risk of earthquakes."
Bert: "Sander, Arianne and Matthijs developed three scenarios of what to do with this warm water. How the heat is used, depends on the location and the situation of the well. For example, the temperature varies per soil layer and depends on the depth of the well. If the well is located in the vicinity of a residential area or glasshouse horticulture area, these are the most attractive end users of the heat. However, many wells are situated in remote, rural areas. Our study reversed the question: Which types of end users are suitable for this energy source and can be established close to the former gas well? This eliminates the need for heat transport, which would lead to extra costs and heat loss. The scenario where a biogas plant is built at the site has been further developed. The heat generated can be used in the fermentation facility and the process complements the optimal reuse of the location. As the well is already connected to the Dutch gas network, this offers the possibility to transport the biogas through the same pipes (after upgrading it to green gas), reducing the costs of sustainable green gas."
Use the existing gas network
"What makes this concept so innovative, is that the user of the heat is moved to the gas location. This bypasses a problem faced by energy transition, namely the need to transport sustainable energy over large distances. Don't forget, The Netherlands is a gas country, with an extensive gas network and many gas extraction sites. It would be a waste not to use these. The students have also drawn up a business case with calculations. The application of this concept can be done in a cost neutral manner, but this requires further calculations. One possible deal breaker is the rise of insurance premiums, because this is a technique that has not been previously applied in the Netherlands. It is all about safety, because you do not want the wells to start leaking. For that reason, each well has to be assessed, to find out what the state of maintenance is and older wells should not be used. Further research is the next step. To make this possible, we are in discussions with various parties, such as knowledge institutes, the oil and gas industry and governments. If it becomes clear that this innovative and sustainable manner of generating energy is feasible, we would like to set up a pilot project. "Because this is the perfect time to give existing gas extraction sites a new purpose!", Christiaan concludes.