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DOE OSTI2025

Roughrider Carbon Storage Hub (Final Report)

The Roughrider Carbon Storage Hub was a 2-year project (October 2023 – September 2025) conducted by the Energy & Environmental Research Center (EERC) focused on advancing the feasibility of a commercial-scale carbon dioxide (CO 2 ) geologic storage hub in McKenzie County, North Dakota. The project’s objective was to investigate the potential that stacked storage complexes (multiple deep saline formations) can safely and economically store at least 50 million tonnes of CO 2 within 30 years. The captured CO 2 would be sourced from industrial emitters including project partner ONEOK, Inc.’s gas-processing plants and a planned gas-to-liquids facility. Drilling of the Roughrider 1 stratigraphic test well (14,979-ft total depth) was completed in November 2024. The wellbore intersected four candidate storage formations: Inyan Kara, Broom Creek, Mission Canyon, and Black Island–Deadwood. Operational challenges, including a stuck drill string, were resolved without long-term impact. A comprehensive logging and coring program was conducted, followed by successful well abandonment and site reclamation. Over 660 ft of 4-in. whole core was retrieved. Core plug samples were processed and analyzed for petrophysical and geochemical properties. Results confirmed promising porosity and permeability in the Inyan Kara and Broom Creek Formations and removal of the Mission Canyon and Black Island–Deadwood horizons from further investigation. Data derived from the logging and coring program were used to improve initial geologic models built from legacy data. CO 2 injection simulations showed that the Inyan Kara alone can feasibly store the target mass of CO 2 . Because of subtle differences in geologic structure and porosity trends between the formations, a stacked storage scenario using the Broom Creek and Inyan Kara Formations resulted in a larger overall plume area than using the Inyan Kara alone. Preliminary CO 2 pipeline routes from the industrial sources were mapped utilizing existing rights of way and evaluated for capacity and cost using U.S. Department of Energy Office of Fossil Energy and Carbon Management/National Energy Technology Laboratory models and U.S. Environmental Protection Agency emissions data. Integrating capture, transport, and storage cost estimates with policy incentives (e.g., 45Q credits) provided a total cost-per-ton analysis. Results indicate that the small scale of the volumes to be transported over the cumulative large distances does not support the project’s financial viability. However, the groundwork laid during this project from geological, regulatory, and social perspectives positions the Roughrider hub site as a promising candidate for commercial carbon storage in North Dakota, especially if the economy of scale is introduced for CO 2 transportation to the hub site.

01 COAL, LIGNITE, AND PEAT↗

DOE OSTI2026

Colorado (Pueblo) Regional DAC Hub TA-1: Feasibility (Phase 0a) (Final Technical Report)

This project supports the U.S. Department of Energy's (DOE) mission to reduce the environmental and climate impacts of fossil fuels and industrial processes, contributing to the goal of achieving net-zero emissions across the U.S. economy. The primary objective is to conduct a feasibility study for a Regional Direct Air Capture (DAC) Hub in the Southern Colorado region, northeast of Pueblo. The geographic construct of this hub is based on the Denver-Julesburg Basin – a geological area where a significant number of geological storage studies have been conducted (See Figure 1). The project will leverage the work of Project Eos, a CarbonSAFE Phase III study led by the Colorado School of Mines and CarbonAmerica. The DAC Hub aims to capture, store, and/or utilize at least 1,000,000 tonnes of CO 2 from the atmosphere annually. To achieve this, the project team is designing a system with an initial capacity of 100,000 tonnes per year. This feasibility-stage project will formulate the Regional DAC Hub concept and team to conduct the relevant analysis, networking and community stakeholder engagement necessary to advance the project to the design stage.

42 ENGINEERING↗

DOE OSTI2026

Building a Trusted Roaming Hub [Slides]

The Trusted Roaming Hub is a U.S. Department of Energy-backed initiative led by the National Laboratory of the Rockies (NLR) to address one of the most persistent challenges in electric vehicle (EV) charging: fragmented roaming, inconsistent interoperability, and insufficient digital trust across charging networks. As EV adoption accelerates and charging infrastructure scales nationwide, today's many-to-many integration model between eMobility Service Providers (eMSPs) and Charge Point Operators (CPOs) has become increasingly brittle, costly, and difficult to secure. The Trusted Roaming Hub introduces a neutral, cybersecurity-forward "switchboard" architecture that enables standardized, secure, and scalable roaming interactions across the EV charging ecosystem. Rather than replacing existing networks or commercial relationships, the hub acts as a trusted intermediary that enforces consistent identity, authentication, authorization, and routing across participants improving reliability for drivers, lowering integration burden for industry, and creating a foundation for future grid-interactive charging services. This read-ahead provides an overview of the problem the hub is designed to solve, the core functional and security concepts behind the architecture, the value proposition to key stakeholders, and the near-term trajectory of the work.

33 ADVANCED PROPULSION SYSTEMS↗

NASA NTRS1977

Effects of reset stators and a rotating, grooved stator hub on performance of a 1.92-pressure-ratio compressor stage

The overall performance and blade-element performance of a transonic fan stage are presented for two modified test configurations and are compared with the unmodified stage. Tests were conducted with reset stators 2 deg open and reset stators with a rotating grooved stator hub. Detailed radial and circumferential (behind stator) surveys of the flow conditions were made over the stable operating range at rotative speeds of 70, 90, and 100 percent of design speed. Reset stator blade tests indicated a small increase in stage efficiency, pressure ratio, and maximum weight flow at each speed. Performance with reset stators and a rotating, grooved stator hub resulted in an additional increase in stage efficiency and pressure ratio at all speeds. The rotating grooved stator hub reduced hub losses considerably.

Lewis, G. W., Jr.↗

NASA NTRS1984

Application of a quasi-3D inviscid flow and boundary layer analysis to the hub-shroud contouring of a radial turbine

Application of a quasi-3D approach to the aerodynamic analysis of several radial turbine configurations is described. The objective was to improve the rotor aerodynamic characteristics by hub-shroud contouring. The approach relies on available 2D inviscid methods coupled with boundary layer analysis to calculate profile, mixing, and endwall losses. Windage, tip clearance, incidence, and secondary flow losses are estimated from correlations. To eliminate separation along the hub and blade suction surfaces of a baseline rotor, the analysis was also applied to three alternate hub-shroud geometries. Emphasis was on elimination an inducer velocity overshoot as well as increasing hub velocities. While separation was never eliminated, the extent of the separated area was progressively reduced. Results are presented in terms of mid-channel and blade surface velocities; kinetic energy loss coefficients; and efficiency. The calculation demonstrates a first step for a systematic approach to radial turbine design that can be used to identify and control aerodynamic characteristics that ultimately determine heat transfer and component life. Experimentation will be required to assess the extent to which flow and boundary layer behavior were predicted correctly.

Civinskas, K. C.↗

NASA NTRS1984

Application of a quasi-3D inviscid flow and boundary layer analysis to the hub-shroud contouring of a radial turbine

Application of a quasi-3D approach to the aerodynamic analysis of several radial turbine configurations is described. The objective was to improve the rotor aerodynamic characteristics by hub-shroud contouring. The approach relies on available 2D inviscid methods coupled with boundary layer analysis to calculate profile, mixing, and endwall losses. Windage, tip clearance, incidence, and secondary flow losses are estimated from correlations. To eliminate separation along the hub and blade suction surfaces of a baseline rotor, the analysis was also applied to three alternate hub-shroud geometries. Emphasis was on elimination of an inducer velocity overshoot as well as increasing hub velocities. While separation was never eliminated, the extent of the separated area was progressively reduced. Results are presented in terms of mid-channel and blade surface velocities; kinetic energy loss coefficients; and efficiency. The calculation demonstrates a first step for a systematic approach to radial turbine design that can be used to identify and control aerodynamic characteristics that ultimately determine heat transfer and component life. Experimentation will be required to assess the extent to which flow and boundary layer behavior were predicted correctly.

Civinskas, K.↗

NASA NTRS1985

Preliminary report on in-flight measurement of rotor hub drag and lift using the RSRA

The Rotor Systems Research Aircraft (RSRA) is a compound helicopter that was test flown as a fixed wing aircraft, with the main rotor blades removed and the rotor hub installed. An onboard rotor load measurement system measured the resulting rotor hub drag and lift. Measured hub drag and lift are plotted for comparison to that predicted by full scale and 1/6 scale model wind tunnel tests. The success of the demonstration gives confidence that planned improvements to the RSRA will allow high accuracy hub drag and lift measurements to be made in flight on a routine research basis.

Acree, C. W., Jr.↗

NASA NTRS1987

Hub flexibility effects on propfan vibration

The significance of hub flexibility in the nonlinear static and dynamic analyses of advanced turboprop blades is assessed. The chosen blade is the 0.175 scale model of the GE-A7-B4 unducted fan blade. A procedure for coupling the effective hub stiffness matrix to an MSC/NASTRAN finite element model is defined and verified. A series of nonlinear static and dynamic analyses are conducted on the blade for both rigid and flexible hug configurations. Results indicate that hub flexibility is significant in the nonlinear static and dynamic analyses of the GE-A7-B4. In order to insure accuracy in analyses of other blades, hub flexibility should always be considered.

Ernst, Michael A.↗

NASA NTRS1987

The hub wall boundary layer development and losses in an axial flow compressor rotor passage

The hub wall boundary layer development in a compressor stage including the rotor passage is experimentally investigated. A miniature five-hole probe was employed to measure the hub wall boundary layer inside the inlet guide vane passage, upstream and far downstream of the rotor. The hub wall boundary layer inside the rotor passage was acquired using a rotating miniature five-hole probe. The boundary layer is well behaved upstream and far downstream of the rotor. The migration of the hub wall boundary layer towards the suction surface corner is observed. The limiting streamline angles and static pressure distribution across the stage were also measured. The mean velocity profiles and the integral properties upstream, inside and downstream of the rotor, and the losses are presented and interpreted.

Murthy, K. N. S.↗

NASA NTRS1985

In-flight measurement of rotor hub drag using the RSRA - A feasibility demonstration

The Rotor Systems Research Aircraft (RSRA) is a compound helicopter that was test flown as a fixed-wing aircraft, with the main rotor blades removed and the rotor hub installed. An onboard rotor load-measurement system measured the resulting rotor hub drag and lift. Measured hub drag and lift are plotted for comparison to that predicted by full-scale and 1/6-scale model wind-tunnel tests. The success of the demonstration gives confidence that planned improvements to the RSRA will allow high-accuracy hub drag and lift measurements to be made in flight on a routine research basis.

Acree, C. W., Jr.↗

NASA NTRS1987

Determination of rotor derivatives and rotor hub force and moment derivatives from flight measurements with the RSRA compound helicopter

A case study of the application of an integrated rotorcraft identification method to the linear modeling of rotor system dynamics and rotor hub loads is presented. Applying the method to flight data obtained from the RSRA compound helicopter, the rotor derivatives in the rotor state dynamic equation are identified along with blade equivalent damping and spring periodic coefficients. A rigid blade flapping equation of motion can be derived from the identified rotor state equation. It is shown that the concept of rotor hub load derivatives is useful for small maneuvering loads. The hub load derivatives can be used to relate the hub dynamic load to rotor/fuselage motion and applied inputs.

Wang, Ji C.↗

NASA NTRS1988

Hub loads analysis of the SA349/2 helicopter

The forces and moments at the rotor hub of an Aerospatiale SA349/2 helicopter were investigated. The study included three main topics. First, measured hub forces and moments for a range of level flight conditions (mu = 0.14 to 0.37) were compared with predictions from a comprehensive rotorcraft analysis to examine the influence of the wake model on the correlations. Second, the effect of changing the blade mass distribution and blade chordwise center of gravity location on the 3/rev nonrotating frame hub loads was studied for a high-speed flight condition (mu = 0.37). Third, the use of higher harmonic control to reduce nonrotating frame 3/rev hub shear forces was investigated. The last two topics were theoretical studies only.

Heffernan, R. M.↗

NASA NTRS1989

Evaluation of VSAERO in prediction of aerodynamic characteristics of helicopter hub fairings

A low-order panel code, VSAERO, was used to predict the aerodynamic characteristics of helicopter hub fairings. Since the simulation of this kind of bluff body by VSAERO was not documented before, the VSAERO solutions were correlated with experimental data to establish their validity. The validation process revealed that simulation of the aerodynamic environment around a hub fairing was sensitive to several modeling parameters. Some of these parameters are body and wake panels arrangement, streamwise and spanwise separation location, and the most prominent one-the wake modeling. Three wake models were used: regular wake, separated wake, and jet model. The regular wake is a wake with negligible thickness (thin wake). It is represented by a single vortex sheet. The separated wake and the jet model in the present application are wakes with finite thickness (thick wake). They consist of a vortex sheet enclosing a region of low-energy flow. The results obtained with the reqular wake were marginally acceptable for sharp-edged hub fairings. For all other cases under consideration, the jet model results correlated slightly better. The separated wake, which seemed to be the most appropriate model, caused the solution to diverge. While the regular wake was straight-forward to apply in simulations, the jet model was not. It requires the user to provide information about the doublet strength gradient on wake panels by guessing the efflux velocities at the wake shedding location. In summary, VSAERO neither predicts accurately the aerodynamic characteristics of helicopter hub fairings nor was cost effective.

Louie, Alexander↗

NASA NTRS1990

Hub loads analysis of the SA349/2 helicopter

Heffernan, Ruth M.↗

NASA NTRS1991

Soft hub for bearingless rotors

Soft hub concepts which allow the direct replacement of articulated rotor systems by bearingless types without any change in controllability or need for reinforcement to the drive shaft and/or transmission/fuselage attachments of the helicopter were studied. Two concepts were analyzed and confirmed for functional and structural feasibility against a design criteria and specifications established for this effort. Both systems are gimballed about a thrust carrying universal elastomeric bearing. One concept includes a set of composite flexures for drive torque transmittal from the shaft to the rotor, and another set (which is changeable) to impart hub tilting stiffness to the rotor system as required to meet the helicopter application. The second concept uses a composite bellows flexure to drive the rotor and to augment the hub stiffness provided by the elastomeric bearing. Each concept was assessed for weight, drag, ROM cost, and number of parts and compared with the production BO-105 hub.

Dixon, Peter G. C.↗

NASA NTRS1993

A parametric study of harmonic rotor hub loads

A parametric study of vibratory rotor hub loads in a nonrotating system is presented. The study is based on a CAMRAD/JA model constructed for the GBH (Growth Version of Blackhawk Helicopter) Mach-scaled wind tunnel rotor model with high blade twist (-16 deg). The theoretical hub load predictions are validated by correlation with available measured data. Effects of various blade aeroelastic design changes on the harmonic nonrotating frame hub loads at both low and high forward flight speeds are investigated. The study aims to illustrate some of the physical mechanisms for change in the harmonic rotor hub loads due to blade design variations.

He, Chengjian↗

NASA NTRS2006

The Competitive Position of Hub Airports in the Transatlantic Market

This article puts forward the argument that the measurement of connectivity in hub-and-spoke networks has to take into account the quality and quantity of both direct and indirect connections. The NETSCAN model, which has been applied in this study, quantifies indirect connectivity and scales it into a theoretical direct connection. NETSCAN allows researchers, airports, airlines, alliances and airport regions to analyse their competitive position in an integrated way. Using NETSCAN, the authors analysed the developments on the market between northwest Europe and the United States (US) between May 2003 and May 2005. One of the most striking developments has certainly been the impact of the Air France-KLM merger and the effects of the integration of KLM and Northwest into the SkyTeam alliance on the connectivity of Amsterdam Schiphol. Direct as well as indirect connectivity (via European and North American hubs) from Amsterdam to the US increased substantially. The main reason for this increase is the integration of the former Wings and SkyTeam networks via the respective hub airports. Moreover, the extended SkyTeam alliance raised frequencies between Amsterdam and the SkyTeam hubs (Atlanta, Houston, for example), opened new routes (Cincinnati) and boosted the network between Amsterdam and France. As a result of the new routes and frequencies, Amsterdam took over Heathrow s position as the third best-connected northwest European airport to the US.

Burghouwt, Guillaume↗

NASA NTRS2023

Global Droughts Connected By Linkages Between Drought Hubs

Quantifying the spatial and interconnected structure of regional to continental scale droughts is one of the unsolved global hydrology problems, which is important for understanding the looming risk of mega-scale droughts and the resulting water and food scarcity and their cascading impact on the worldwide economy. Using a Complex Network analysis, this study explores the topological characteristics of global drought events based on the self-calibrated Palmer Drought Severity Index. Event Synchronization is used to measure the strength of association between the onset of droughts at different spatial locations within the time lag of 1-3 months. The network coefficients derived from the synchronization network indicate a highly heterogeneous connectivity structure underlying global drought events. Drought hotspot regions such as Southern Europe, Northeast Brazil, Australia, and Northwest USA behave as drought hubs that synchronize regionally and with other hubs at inter-continental or even inter-hemispheric scale. This observed affinity among drought hubs is equivalent to the ‘rich-club phenomenon’ in Network Theory, where ‘rich’ nodes (here, drought hubs) are tightly interconnected to form a club, implicating the possibility of simultaneous large-scale droughts over multiple continents.

Drought↗