The Modified UpDraft Tower (MUT) Technology for Geothermal Power Generation and Rankine Cogeneration research investigation was a nine month, @$256,000 National Science Foundation (NSF) Grant. The major goal of this investigation was to validate the technical viability of the Modified Updraft Tower concept, using scientific methods, well-reasoned and well-organized activities including computation, measurement, observations, and analyzation of computer models, based on sound theory, to find operational boundaries, and optimum functional parameters. The primary outcome was the computation modeled simulations of coherent, displaced air with sufficient velocity and mass flow rate, induced by a specific thermal energy input and MUT geometrical configurations, to demonstrate critical functions and elements that determine an operational range and operational envelope of the MUT. The specific goal of this funded research was the production and analysis of computer-based simulation models, including:

• Air intake velocity for a given set of pressure differentials.
• Thermal/Pressure gradient disruption.
• Expected exhaust air flow generated.

Additionally, goals of market research and broader impacts substantiation which involved completing the Beat the Odds Boot Camp and Customer Discovery helped define the MUT commercialization potential, identification of specific initial customers, innovative products and services derived from MUT technology including development partners, market growth possibilities, and the processes needed to build lasting sustainable societal and economic impact.

The NSF Grant (2222965) was awarded in 2023 to PowerSILO Inc., and was supported by two outside consulting firms, FEAmax Engineering Service LLC of North Carolina and CZero Inc. of Colorado, with both firms unknowingly participating in a single blind CFD modeling, simulation, and investigation effort. PowerSILO’s initial work focused on demonstrating that harnessing Rankine Cycle process waste heat (or RE Geothermal) to create a buoyancy driven air flow generated in a vertical tower configuration is viable for extracting the resulting kinetic energy as electricity with the use of a novel Vertical Axis Vertical Airflow Nozzled Turbine (VAVANT) design. Though unanimous, positive concurrence from both firms regarding “the viability” to the geometry investigated was not achieved; both teams did produce independent CFD models and simulation data that substantiate significant induced airflow and MUT power output potential. This phase of investigation was expected to provide neither a highly refined, efficient, or complete product, but only to serve as validation of the concept and proof of the physics supporting said concept.  A result of this exploration is that the PowerSILO team pivoted from an internal heat exchange arrangement to a forced air configuration.  The results of this investigation led by PowerSILO validates this basic concept of a Modified Updraft Tower as functional and that further investigation is needed to refine the precise operating envelopes, required energy inputs, specific configurations, material selection, and construction methodologies to fully determine the commercial viability of any products or services developed from this technology. PowerSILO’s investigation conducted 14 CFD simulations of digital models that included baseline cases, ground towers, and forced air simulations. Of the 10 Forced Air CFD simulations conducted, 6 have configurations that demonstrate and document an average VAVANT turbine velocity of 14.7meters/s, with a highest measured velocity of 28.5meters/s through the @19.5meter diameter VAVANT Turbine. Additionally, an average mass flow rate of 133m³/s and a highest measured mass flow rate of 188m³/s through the VAVANT was observed.

It is thus premature to state that the technology and results produced at this stage is not viable, and not worthy of continued investigation especially given the consideration that the potential impacts and outcomes are substantial.

Based on the simulation results, when both Forced Air Inlet1 and Draft Air Inlet2 are velocity inlets, the parameters like velocity and temperature of the air at the VAVANT turbine outlet can actually be calculated using theoretical formulas such as 𝜌𝜌Av=const, cmt =const, etc. The CFD analysis results are consistent with the theoretical formulas.  The simulation results when Forced Air Inlet1 is a velocity inlet and Draft Air Inlet2 is a pressure Inlet yield the same results when consideration of the pressure gradient is respected.  When there is a known significant pressure difference between the Draft Inlet2 and the VAVANT turbine outlet, the pressure difference generates a driving buoyancy force. At this time, the velocity calculated according to the theoretical formula may have some errors, however the simulation calculations are more accurate.

The conclusion PowerSILO derives from this data is that further investigation, with minimal to marginal redesign and refinements, will prove the technology application as commercially viable for specific industrial and energy sector applications driving increased Cogeneration, Eefficiency and Geothermal based Renewable Energy.

The PowerSILO MUT concept validation supports continued research and development towards commercialization of marketable products and services. For more information, visit www.powersilo.energy.

Last Modified: 11/10/2023
Modified by: Rod Nash