Dr.ir. J.M. Bloemendal

Sustainable energy has received substantial attention over the last years/decades. Heat is the largest part of the worldwide energy requirement (space heating/cooling, industry, etc.). As with many other renewable or sustainable energy sources, also with heat, the biggest challenge is dealing with the variability in the availability and demand. Heat storage is one of the major solutions to match heat availability to demand. Aquifer Thermal Energy Storage (ATES) is, therefore, one of the important geothermal energy technologies needed to utilize sustainable heating and cooling systems of buildings – and in particular, provides cheap and large scale storage (see section on ‘Background ATES development’ below). Both, high quality research and education as well as large scale adoption of ATES technology are needed during the coming decades at national and international level.

Martin Bloemendal works on various research projects to develop ATES technology and sustainably use the subsurface for renewable heating and cooling systems. Next to research he is also involved in education by supervision of Bsc and Msc thesis projects and lecturing in various courses. Martin Bloemendal is a part-time researcher. Next to his work at Delft University of Technology he works at KWR a Dutch research institute.  At KWR Martin Bloemendal is a researcher also working on Aquifer Thermal Energy Storage (ATES) projects, often applying the concepts developed at the TU Delft in pilot projects in practice. Next to that, Martin Bloemendal is also board member of the Dutch branch organization for geothermal energy storage systems.

The subsurface plays a crucial and growing part in sustainably cooling and heating buildings. Martin Bloemendal’s vision is that the enormous potential of this source of renewable energy must be put to is maximum use and must be available for future generations.

Background ATES development

Geothermal energy storage is of crucial importance to sustain energy system

To meet greenhouse gas emission reduction goals, the heating and cooling demand of buildings is of crucial importance to sustain, as it is about 50% of the total energy consumption (Jong, 2016). As heat can only be transported over small distances, different studies indicate that local solutions need to be found to sustain space heating and cooling (Hoogervorst, 2017; Ministry-of-Economic-affairs, 2016). In moderate climates and industrialized areas both heating and cooling capacity is abundantly available, however mostly not at the right time and/or at the right location. The Dutch government wants to utilize waste heat from industries and power plants (Kamp, 2015; Ministry of Economic Affairs, 2016), then supply (constant) needs to be met with demand (seasonally varying). Also with sustainable heat sources, like geothermal and solar heat, there is a mismatch in time between availability and demand.

Storage facilities are needed to overcome those discrepancies in time at individual building as well as local level. There are many options for heat storage, considering the required capacity and cost, subsurface heat storage is by far the cheapest and most feasible technology in areas where sandy layers with groundwater exist (IEA et al., 2013)[1]. Recent research showed that in the Dutch energy system without gas, about 75% of the required heating and cooling needs to come from the subsurface (Naber et al., 2016); both geothermal mining as well as heat storage and recovery from the subsurface.

Example of waste heat and variable heat utilization with heat storage 

Up-scaling geothermal energy storage requires education, research and development

Both recognized as well as relatively new storage technologies need substantial research and development to allow for utilization of their expected potential.  An overview of different geothermal technologies is given in.

Recognized geothermal storage systems (ATES and BTES) use ~5°C storage for cooling and up to 20°C for heating in combination with a heat pump. Although there are already many of such storage systems operational in The Netherlands, their level of adoption is still very modest; 0.2 % for non-houses and 1% for houses (Agterberg, 2016). The limited adoption rate is caused by both over-cautious legislation and the fact it is only applied in new buildings due to the required level of insulation. Despite the limited adoption, many cities experience scarcity of subsurface space for such systems, caused by too many safety factors regarding the mutual distance between such systems (Bloemendal et al., 2014).

Research needs to focus on application in existing buildings and governance of the local subsurface; maximizing overall CO2-emission reduction, rather than protection of individual wells. An example is the running ATES smart grids project funded by NWO,  facilitating 3 PhD’s and 2 postdocs. In this research DCSC, TPM and CEG cooperate in a first effort to solve the optimal use of the subsurface with ATES systems. With the ATES systems present on campus this research can be further developed and demonstrated at TU Delft and may deliver additional Msc’s, Phd’s and postdoc positions.

In densely build areas with a large heat demand (i.e. existing buildings & houses), district heating is a more efficient and cost effective option than low temperature energy storage. As discussed above (local) district heating networks also require large scale thermal energy storage facilities, only at much higher temperatures compared ATES systems. Given the potential role of high temperature ATES in the energy transition, local authorities allow pilot studies despite current legislation prevents geothermal energy storage at temperatures higher than 25°C (Ministry-of-Infrastructure-and-Environment, 2013).

Fundamental research to develop this technology needs to focus on 3 issues; 1) optimization of recovery efficiency; large temperature differences in the subsurface cause buoyancy flow affecting recovery efficiency, 2) sustainable operation; large temperature changes cause chemical equilibriums to shift, the resulting depositions cause clogging of the groundwater wells, and 3) environmental effects; heating to upper subsurface layers and the associated water quality effects in subsurface layers used for drinking water production. A high temperature storage in combination with the geothermal mining (DAP) project will boost TU-Delft research on this still undeveloped field. Pilot locations are very limited in the Netherlands, a well monitored pilot at the campus will facilitate several Phd and postdoc positions.

Overview of different geothermal technologies as applied in The Netherlands.

References

  • Agterberg, F.A., 2016. Roadmap Bodemenergie RVO.
  • Bloemendal, M., Olsthoorn, T., Boons, F., 2014. How to achieve optimal and sustainable use of the subsurface for Aquifer Thermal Energy Storage. Energy Policy 66, 104-114.
  • Hartog, N., Bloemendal, M., Slingerland, E., van, W.A., 2017. Duurzame warmte gaat ondergronds. VV+ sept-okt 17.
  • Hoogervorst, N., 2017. Toekomstbeeld klimaatneutrale warmtenetten in Nederland. PBL, Den Haag.
  • IEA, ETSAP, IRINA, 2013. Thermal Energy Storage, Technology Brief. iea, ETSAP, IRINA.
  • Jong, K.d., 2016. Warmte in Nederland (heat in the Netherlands), Steenwijk.
  • Kamp, H., 2015. Warmtevisie, ministry of economic affairs, Den Haag.
  • Ministry-of-Economic-affairs, 2016. Energieagenda, Naar een CO₂-arme energievoorziening. Ministry of Economic affairs, Den Haag.
  • Ministry-of-Infrastructure-and-Environment, 2013. Waterregeling (WaterAct), in: Ministry-of-Infrastructure-and-Environment (Ed.), Den Haag.
  • Naber, N., Schepers, B., Schuurbiers, M., Rooijers, F., 2016. Een klimaatneutrale warmtevoorziening voor de gebouwde omgeving – update 2016. CE-Delft, Delft.
  • Stam, S., 2016. Enorme opslagtank geeft speelruimte in levering warmte, Energiegids.nl.
[1] Recently NUON installed an €8m thermal store of 20.000 m3, enough to cover 2 days of heat delivery in a part of the Amsterdam district heating grid (Stam, S., 2016. Enorme opslagtank geeft speelruimte in levering warmte, Energiegids.nl.). A basic geothermal storage system of about €0.5m would utilize 500.000 m3 of storage space, with the upside that such a storage is in the subsurface, thus it is not seen or heard  yielding valuable space at surface level for another use.

Martin Bloemendal

Part-time Researcher