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- Senior project about Deep Direct Use (DDU) geothermal
Senior project about Deep Direct Use (DDU) geothermal
Posted by Morgan White on September 25, 2020
Lauren Kumle, Tess Sobol, Jaboc Heglund, and Tommy Robey in CEE 493 - Sustainable Design Engineering Technology worked with Dr. Andy Stumpf in Fall 2020 on a Deep Direct Use (DDU) geothermal proposal for north campus.
Dr. Stumpf provided this information to the team in September:
If your team is interested, you might consider a different technology for geothermal energy at Newmark Civil Engineering Laboratory. Specifically a deep direct-use (DDU) geothermal energy system (GES). I suggest this because I am not certain there is enough ground space at Newmark for a geothermal borefield like at CIF. The advantages of DDU GES is it requires fewer wells, and there would be enough thermal energy extracted to condition space in multiple buildings. Essentially, the DDU GES comprises extraction and injection wells (likely 2 of each needed) to access geothermal fluids (brine) from deeper bedrock formations. Under campus, one of the potential bedrock formations, the St. Peter Sandstone, lies at ~2,000 feet depth and contains an abundant amount of fluid at 78-82°F. When I last talked to Professor Liang Liu (who recently retired from College of Engineering), he was very interested in a study for DDU GES for the Engineering quad (south of Grainger library). So I think your findings from this type of system would be timely and more likely to be implemented.
My colleagues and I just completed a feasibility study of DDU GES for six agricultural research facilities on the South Farms (see summary paper attached).
The focus was on the deeper Mt. Simon Sandstone (lying at >6000 feet depth) because we were interested in extracting the hottest brine (110-130°F) since some of the farms needed to make hot water. They are not connected to the steam and hot/cold water energy system servicing the main part of campus, so propane and natural gas are the primary fuels. However, the St. Peter Sandstone would be an alternative… and this formation is also being considered for cooling buildings.
If you are interested in looking at DDU for the Newmark site, I can share the report with you. It should contain much of the information you need. Some of colleagues can help you with the life cycle costs and mechanical energy system analyses. Completing this project would also help researchers on campus compete for funding from DOE to complete tests wells which will be needed to validate your findings. DOE is very interested in developing DDU GES in non-volcanic areas of the US, especially for district-energy systems. Cornell University just received funding from DOE for a test well to develop a DDU GES on their campus, but they will most likely have to drill >15,000 feet into the Precambrian granite develop the system. They are looking to generate electricity with very hot water. https://eos.org/science-updates/exploring-by-boring-geothermal-wells-as-research-tools.
Doing a rough calculation, I think constructing a DDU GES would be of similar cost to a shallow borefield with 50-100 wells. The DDU GES would be much more efficient since you are directly using the heated brine and not trying to conduct heat in the ground. The payback period would be much quicker since it will be servicing more than one building.
On 9/25/2020, Lauren, Tommy, and Jacob met with Dr. Stumpf. He provided the following update:
I had a meeting with Lauren Jacob and Tommy today about their design project. I suggested they look at a DDU system that would heat/cool 4 buildings (Newmark, DCL, Uni High, and Siebel Center). I guess the number of buildings will depend on the amount of energy that can be extracted from the geothermal reservoir. I also suggested they look at the shallowest reservoir, the St. Peter Sandstone. As part of their analysis, they indicated there is a need for building level energy use data.