Final Scientific/Technical Report SOFC’s for FLIGHT (Fuel-flexible, Lightweight, Internally-reformed, Gas-turbine Hybridized for Transportation)
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33 ADVANCED PROPULSION SYSTEMS↗
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Small engine technology programs
Small engine technology programs being conducted at the NASA Lewis Research Center are described. Small gas turbine research is aimed at general aviation, commutercraft, rotorcraft, and cruise missile applications. The Rotary Engine Program is aimed at supplying fuel flexible, fuel efficient technology to the general aviation industry, but also has applications to other missions. There is a strong element of synergism between the various programs in several respects. All of the programs are aimed towards highly efficient engine cycles, very efficient components, and the use of high temperature structural ceramics. This research tends to be generic in nature and has broad applications. The Heavy Duty Diesel Transport (HDTT), rotary technology, and the compound cycle programs are all examining approached to minimum heat rejection, or adiabatic systems employing advanced materials. The Automotive Gas Turbine (AGT) program is also directed towards ceramics application to gas turbine hot section components. Turbomachinery advances in the gas turbines will benefit advanced turbochargers and turbocompounders for the intermittent combustion systems, and the fundamental understandings and analytical codes developed in the research and technology programs will be directly applicable to the system projects.
Niedzwiecki, Richard W.↗
Small engine technology programs
Described here is the small engine technology program being sponsored at the Lewis Research Center. Small gas turbine research is aimed at general aviation, commuter aircraft, rotorcraft, and cruise missile applications. The Rotary Engine program is aimed at supplying fuel flexible, fuel efficient technology to the general aviation industry, but also has applications to other missions. The Automotive Gas Turbine (AGT) and Heavy-Duty Diesel Transport Technology (HDTT) programs are sponsored by DOE. The Compound Cycle Engine program is sponsored by the Army. All of the programs are aimed towards highly efficient engine cycles, very efficient components, and the use of high temperature structural ceramics. This research tends to be generic in nature and has broad applications. The HDTT, rotary technology, and the compound cycle programs are all examining approaches to minimum heat rejection, or 'adiabatic' systems employing advanced materials. The AGT program is also directed towards ceramics application to gas turbine hot section components. Turbomachinery advances in the gas turbine programs will benefit advanced turbochargers and turbocompounders for the intermittent combustion systems, and the fundamental understandings and analytical codes developed in the research and technology programs will be directly applicable to the system projects.
Niedzwiecki, Richard W.↗
Hydrogen Storage for Flexible Fossil Fuel Power Generation: Integration of Underground Hydrogen Storage with Gas Turbine (Final Report)
As the nation continues to encourage, through market structures and financial incentives, the proliferation of intermittent renewable electricity, how to optimize the ever-changing electric grid and identify means to retain and improve resilience, while ensuring continued reductions in GHG emissions, will be critical. According to Bloomberg, wind & solar generated 10.5% of US electricity in 2020 and that percentage continues to grow. In support of expanding renewable energy use, and to address its intermittent nature, this project will develop the Hydrogen Storage for Flexible Fossil Fuel Power Generation platform that is dispatchable, reliable, repeatable and have the ability to produce zero or negative carbon power while interfacing with geology capable of CO2 and hydrogen storage. GTI Energy (GTIE) and team members Illinois State Geological Survey (ISGS), Mitsubishi Heavy Industries America (MHIA), Ameren Illinois, Hexagon Purus, and the Low Carbon Resources Initiative (LCRI) completed a Phase I Conceptual Study under contract DE-FE0032012 for Hydrogen Storage for Flexible Fossil Fuel Power Generation: Integration of Underground Hydrogen Storage with Gas Turbine. The Hydrogen Storage for Flexible Fossil Fuel Power Generation platform addresses the intermittent nature of the expanding use of Variable Renewable Energy (VRE) generation. The low cost of the electricity (COE) generated results in greater dispatch and more operation at higher power levels (higher efficiency), fewer short intervals, and fewer start/stop cycles. The reliable, resilient system can produce zero carbon power and store hydrogen. It will demonstrate hydrogen storage in geologic formations like those used in natural gas underground storage thus enabling large scale storage of hydrogen in sedimentary strata across the United States rather than in geographically restricted salt caverns. The Phase I study confirmed the system is feasible and generates power at lower cost than other low carbon approaches. The demonstration defines the pathway for broad commercial application and will accelerate the development of larger systems suitable for centralized utility scale electricity production. The study advanced the maturity of the H 2 storage-based system with flexible power generation by completing a Pre-FEED study (Phase II). The Pre-FEED focused on the selected Energy Farm on the University of Illinois Urbana-Champaign (UIUC) site that includes above ground and underground hydrogen storage, low-carbon hydrogen production (GTI’s Compact Hydrogen Generator, CHG) with underground CO2 sequestration, and a 40-MW class gas turbine. The Pre-FEED addressed the entire system and its interconnection to the natural gas and electric grid and mitigation of key risks, such as storage behavior, load-following, and system operation. During Phase 1 of the project, the team completed key tasks, which moved the entire demonstration project, specific components and approaches closer to commercialization. These Phase I Accomplishments include: Completing System Requirements Review; Completing System Layout and Modeling - Heat & Mass Balance and Process Flow Diagram; Completing modelling of 9 turbine performance cases; Evaluating rock strata for underground storage of hydrogen and sequestration of carbon dioxide; Completing initial modelling of underground storage of hydrogen and withdrawal with evaluation of loss and water production; Identifying roadable storage for above ground hydrogen storage; Identifying existing electrical infrastructure for receiving/delivering electricity; Identifying existing gas supply infrastructure for receiving natural gas; Document concept design/development plans in required reports. Conclusions: The 12-month Feasibility study in Phase I study was completed and confirmed the system is feasible and generates power at lower cost than other low carbon approaches and even lower cost than the reference NGCC plant without carbon capture when taking advantage of 45Q carbon credits. The study enabled the fidelity of the concept to be improved and allowed identification of the requirements for the system. Defining the individual system and component requirements was performed via the system requirements review with the whole team. These requirements were then incorporated into and iterated with our Heat & Mass Balance process model and process flow diagrams were generated to reflect the overall system. This information was then used to complete the TEA and show economic feasibility. Large scale non-salt geologic storage of hydrogen is an enabling technology for a hydrogen-fired turbine that can be retrofitted into large-scale electric generating units (EGU). Our demonstration will include 428 MWh or ~4 hours full load of hydrogen storage (above and underground). Carbon capture inherent to the CHG process can capture 90% CO 2 (with upgrades to >98%). This system provides a COE of 23% savings relative to an NGCC with a post combustion amine system. Our proposed storage system decouples carbon capture and hydrogen production from power production; therefore, we expect our proposed system’s efficiency and variable COE to be superior resulting in overall higher dispatch and reduced deep cycling. Our demonstration will be full to multi-day hydrogen storage and has the potential for longer (seasonal) duration commercially. The demonstration defines the pathway for broad commercial application and will accelerate the development of larger systems suitable for centralized utility scale electricity production.
03 NATURAL GAS↗
Metal-Supported Solid Oxide Fuel Cells for Natural Gas
Solid oxide fuel cells (SOFCs) are high temperature energy conversion devices that produce electricity efficiently and sustainably. High operating temperatures required for SOFC function endow these devices with many advantages including fuel flexibility and high conversion efficiencies. Fuel flexibility, in particular, distinguishes SOFCs from other types of fuel cells that operate with clean H 2 only, and enables operation with natural gas (NG). LBNL has developed metal supported SOFCs (MS-SOFCs) with unique symmetrical architecture that offer several advantages over state of the art (SoA) ceramic SOFC models including inexpensive materials, rapid start up capability, increased mechanical strength and high tolerance to thermal cycling, Fig 1. These advantages make LBNL MS-SOFCs uniquely suited for fast start-up, portable, and mobile backup generator applications. Specifically motivating this work was a scenario of backup generators fueled by pipeline natural gas delivered from SoCalGas in the event of an electric grid shut down. This project investigates the feasibility of using MS-SOFCs with pre-reformed natural gas as well as direct on-cell reforming of simulated natural gas both with and without sulfur.
03 NATURAL GAS↗
Advanced Anode for Internal Reforming and Thermal Management in Solid Oxide Fuel Cells
Solid oxide fuel cell (SOFC) is an efficient and clean electrical power generation system compared to conventional combustion based technologies with energy efficiency reaching as high as 85-90% in co-generation mode (electricity and heat). Other advantages of SOFCs are hybridization, modularity of construction, small CO 2 foot print per kWh of generated electricity and fuel flexibility. Hydrocarbons present in the gaseous fuel is utilized in SOFCs by internal or external reforming. There are two different internal reforming concepts: Direct Internal Reforming (DIR) and Indirect Internal Reforming (IIR). For DIR operation, the endothermic reforming reaction and the exothermic reaction from the oxidation reaction are operated together in the single unit eliminating the requirement for a separate fuel reformer. This configuration also simplifies the overall system design, making SOFC more attractive and efficient means of producing electrical power. The main advantage of the DIR type of operation is that the H 2 or CO consumption by the electrochemical reaction could directly promote the conversion of methane at the anode side of the fuel cell resulting in high conversion and high efficiency. The DIR operation, however, requires an anode material that has desired dual catalytic (hetero and electro) properties for reforming reaction and electrochemical reactions. The anode materials also need to remain resistant to carbon formation at the operating temperature and atmosphere with stable cell performance. Another requirement is to match the reforming reactions and electrochemical reactions to avoid local cooling or overheating, which can result in mechanical failure due to thermally induced stresses. Direct internal reforming (DIR) of hydrocarbon fuels simplifies the overall SOFC system design making it more attractive and efficient for producing electrical power. Low cost alloy anodes for distributed internal reforming of methane and other hydrocarbon fuels offer increased fuel-flexibility, reliability, and long term performance stability of solid oxide fuel cells (SOFC). The research program examined modification of the chemical compositions and microstructure of high entropy alloy (HEA) anode materials using thermochemical calculations and process simulation and modeling to achieve distributed reforming over the entire anode to eliminate hot zones. Cell fabrication and testing of the HEA anodes using button cell configuration has been performed to demonstrate the advantages of new anode over traditional Ni-YSZ anodes for distributed reforming and carbon free operation. Technical accomplishments include identification and synthesis of HEA carbon-resistant anode, demonstration of reduction in reforming rate confirmed by GC and modelling data validating effectiveness for thermal management in cell/stacks, electrochemical testing of HEA anode in single cell (HEA-GDC||YSZ||LSM-YSZ) and Characterization of pretest and posttest anode materials by TEM and SEM-EDS confirming carbon-free operation.
30 DIRECT ENERGY CONVERSION↗
Investigating the Combustion Performance of Dual Fuel Combustion with Diesel and Port Injected Hydrogen in a Large Bore Locomotive Engine
The heavy-duty transportation sector has primarily relied on conventional diesel combustion engines given their reliability and high thermal efficiency relative to spark ignition engines, but increased focus on reducing greenhouse gas emissions has led to investigation into alternative fuels. Gaseous hydrogen fuel has garnered a great deal of recent interest in the engine community given it has zero carbon, but hydrogen is not available at the scale and cost that petroleum fuels are currently available, and this is a barrier to adoption for industries that are looking to decarbonize their operations. Because of the fuel flexibility provided, dual fuel technology offers a pathway for some industries to adopt hydrogen as a fuel source while maintaining sufficient flexibility in times and locations where the new fuel is not yet available. This computational study investigates dual fuel combustion in a large bore locomotive engine architecture using direct injected diesel and port injected gaseous hydrogen fuel. With an optimal port fuel injection configuration from previous work, simulations of varying substitution ratio, compression ratio, manifold air temperature, diesel injection timing, and diesel injection pressure were performed to understand their effect on combustion performance. Results indicated that both increased substitution ratio and higher intake air temperature accelerates hydrogen flame propagation and can result in high peak cylinder pressures. Additionally, diesel injection timing and injection pressure were demonstrated as effective methods for controlling dual fuel combustion heat release rates.
ODonnell, Patrick Christopher↗
NASA Project Develops Next-Generation Low-Emissions Combustor Technologies
NASA's Environmentally Responsible Aviation (ERA) Project is working with industry to develop the fuel flexible combustor technologies for a new generation of low-emissions engine targeted for the 2020 timeframe. These new combustors will reduce nitrogen oxide (NOx) emissions to half of current state-of-the-art (SOA) combustors, while simultaneously reducing noise and fuel burn. The purpose of the low NOx fuel-flexible combustor research is to advance the Technology Readiness Level (TRL) and Integration Readiness Level (IRL) of a low NOx, fuel flexible combustor to the point where it can be integrated in the next generation of aircraft. To reduce project risk and optimize research benefit NASA chose to found two Phase 1 contracts. The first Phase 1 contracts went to engine manufactures and were awarded to: General Electric Company, and Pratt & Whitney Company. The second Phase 1 contracts went to fuel injector manufactures Goodrich Corporation, Parker Hannifin Corporation, and Woodward Fuel System Technology. In 2012, two sector combustors were tested at NASA's ASCR. The results indicated 75% NOx emission reduction below the 2004 CAEP/6 regulation level.
Lee, Chi-Ming↗
Decarbonizing Cooking Appliances With Hydrogen
A novel hydrogen compatible heterogeneous burner prototype was engineered, fabricated, and evaluated for applications in cooking appliances. The key features targeted and accomplished under this effort included fuel flexibility, tolerance to high hydrogen concentrations (up to 85% in atmospheric design and 100% in premixed design), wide range of thermal power ratings, thermal cycling, reliability, and most importantly safety. The burner was operated in the range of 3000 – 12,000 Btu/h under all practical operating conditions (cold start, hot restart, fuel concentration variance). The heterogeneous oxidation burner technology was evaluated for overall performance targeting safety, reliability, emissions, fuel flexibility, and energy efficiency in a commercial RV and residential cooking range appliance prototypes. The burner demonstrated safe and reliable performance generating infrared heating energy without the consumption of any parasitic energy while using low-cost materials. Performance evaluation testing of the novel IR burner demonstrated fuel flexibility with hydrogen blended natural gas while significantly eliminating air pollutants like NOx and methane and increasing the energy efficiency by up to 20%.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Flexible Natural Gas/Hydrogen CHP System
This project included design, development, and demonstration of a cost-effective and scalable, unique-to-the-industry 2.0 MWe fuel-flexible Caterpillar G3516 CHP genset that can run on 100% hydrogen, 100% natural gas, and up to 25% blends of hydrogen in natural gas (volume basis). This was accomplished based on over two years of extensive R&D work done on a single-cylinder engine for developing innovative hydrogen fueling, combustion, air, and electronic control systems design and strategies. Findings from the single-cylinder engine work were scaled up and applied for modifications of and lab testing and development of a 2.0 MWe 16-cylinder G3516 fuel-flexible engine-genset and electronic controls systems. During this testing and development in the engine lab, the genset was run on 100% hydrogen, 100% natural gas, and up to 25% blends of hydrogen in natural gas (volume basis) and its steady-state and transient performance and emission were documented.
03 NATURAL GAS↗
Advanced Modular Sub-Atmospheric Hybrid Heat Engine (Final Report)
The Phase 1 Final Technical Report describes the results of the work completed during the “Advanced Modular Sub-Atmospheric Hybrid Heat Engine” project. A key part of the Phase 1 work was the completion of a thermodynamic cycle analysis for the MHHE at the selected module size. The hybrid heat engine has been developed as a modular unit (sized in the range of 500kW – 60MW) that can be used with modular coal or biomass gasifiers, with distributed power generation systems, with large power plants comprised of multiple generating units, and with natural gas compression stations. The MHHE will provide cleaner, more efficient, and lower cost generation with better load following capabilities than existing competing technologies with a singular generating source such as solar farm, gas turbine, or combustion engine. The drivers of the MHHE technology are: benefits of modular power generation (reduced equipment cost, construction cost and implementation time, connection ready on delivery, flexible scalability, serviceability), fuel flexibility, lowest cost power generation and reduced emissions.A logical progression of work and a clear path forward toward meeting the FOA goals and objectives have been established. Namely, a preliminary market analysis and primary fuel identification was completed first and then the modularity of the system was defined. The benefits of the proposed hybrid and modular heat engine were described when applied to modular coal gasifiers, distributed power generators, and larger power plants. Based on the market analysis, modularity, and chosen primary fuel, a conceptual design and layout of the hybrid heat engine was developed, analyzed, and characterized. The technology gaps already identified have been reviewed and expanded upon, and a test plan to address these gaps through bench scale testing in Phase 2 has been developed. Cost estimate methodology and considerations in support of a potential Phase 2 project have been described.
08 HYDROGEN↗
Thermophotovoltaic Heat Engine
This project was aimed at developing a thermophotovoltaic device that efficiently converts thermal radiation to electrical power. Historically, TPV devices have been plagued by poor robustness; this project sought to overcome this by merging innovations in nanophotonics, photovoltaics, and robust thermal engineering. Efforts were focused on developing high efficiency TPV devices which may drastically alter the electricity sector by enabling efficient (> 20%), fuel-flexible (any combustion fuel), distributed (< 10 kW) power generation. The project research identified the technical performance limits, technology differentiator, and customer value proposition for TPV devices and established technical performance requirements for a minimum viable product.
30 DIRECT ENERGY CONVERSION↗
Benefits of Dual Fuel Heat Pump Grid-responsive Control: A Model-based Control Optimization Approach Using Building and Equipment Co-simulation
Conventional dual fuel heat pumps lack the intelligent control mechanisms to efficiently manage the switch between heat pump and furnace, leading to sub-optimal energy usage and, in some cases, increased operating costs. To resolve this gap, this study applies optimized control on hybrid heat pumps. With a focus on equipment control strategies, we compare the performances of five spacing heating equipment, including a conventional heat pump (HP), a conventional furnace, a dual fuel heat pump (DFHP) with conventional control, a dual fuel heat pump with smart control, and a novel seamlessly fuel flexible heat pump (SFFHP). While DFHP runs on either gas or electricity at any given moment, SFFHP concurrently consumes gas and electricity by continuously optimizing the proportion of each. In this research, a co-simulation framework is developed by integrating a building envelope model with a physics-based heat pump simulation model to analyze the benefits of grid-responsive controls of DFHP and SFFHP. The model-based optimal controls adjust the operation of the heat pump and gas furnace based on utility price signals and marginal grid emission to minimize utility cost and CO 2 emissions for multiple climate zones, different utility tariffs, and marginal grid emission scenarios. Case studies in Chicago and Los Angeles demonstrate that SFFHP and DFHP, with model-based optimal control, can deliver significant reductions in peak demand, utility cost, and CO 2 emission. In Chicago, SFFHP and smart controlled DFHP yield up to 64.7% and 61.7% utility cost reduction and up to 15.7% and 8.5% CO 2 emission reduction compared to the gas furnace. In Los Angeles, SFFHP and smart controlled DFHP achieve up to 43.6% and 40.1% utility cost reduction and up to 13.8% and 14.1% CO2 emission reduction compared to conventional heat pumps. In conclusion, by leveraging the fuel flexibility nature of dual fuel heat pumps, the model-based control optimization approach makes dual fuel heat pump an attractive option for demand response programs.
Control↗
Combustion technology overview
An overview of combustor technology developments required for use of broadened property fuels in jet aircraft is presented. The intent of current investigations is to determine the extent to which fuel properties can be varied, to obtain a data base of combustion - fuel quality effects, and to determine the trade-offs associated with broadened property fuels. Subcomponents of in-service combustors such as fuel injectors and liners, as well as air distributions and stoichiometry, are being altered to determine the extent to which fuel flexibility can be extended. Finally, very advanced technology consisting of new combustor concepts is being evolved to optimize the fuel flexibility of gas turbine combustors.
Niedzwiecki, R. W.↗
Cooperative Research and Development Agreement between National Energy Technology Laboratory and OxEon Energy LLC (Abstract)
The National Energy Technology Laboratory (NETL) will collaborate with OxEon Energy LLC (OxEon) to apply NETL’s patented single step electrode infiltration technique on OxEon solid oxide fuel cells (SOFC) for Electric Vertical Takeoff and Landing (eVTOL) aircraft applications below one megawatt. The expanded application of the OxEon solid oxide cell technology on eVTOL aircraft seeks to demonstrate a high performance, durable SOFC system that will produce more electricity per weight based on possible operation on ammonia as fuel. NETL’s single-step electrode infiltration technique addresses these challenges by introducing a highly active nanocatalyst material into the SOFC electrode microstructure to improving cell performance, longevity, and fuel flexibility. Specifically for this project, OxEon will incorporate NETL’s technology to generate a small stack of cells (1 kW output) to demonstrate a fuel flexible system at a relevant scale. NETL will apply its infiltration technology to cells supplied by OxEon, test the effectiveness of the infiltration internally at NETL based on performance in hydrogen, and then supply infiltrated cells to OxEon and Pacific Northwest National Laboratory for independent confirmation and for the 1 kW stack test.
30 DIRECT ENERGY CONVERSION↗
Catalytic autothermal reforming increases fuel cell flexibility
Experimental results are presented for the autothermal reforming (ATR) of n-hexane, n-tetradecane, benzene and benzene solutions of naphthalene. The tests were run at atmospheric pressure and at moderately high reactant preheat temperatures in the 800-900 K range. Carbon formation lines were determined for paraffinic and aromatic liquids. Profiles were determined for axial bed temperature and composition. Space velocity efforts were assessed, and the locations and types of carbon were recorded. Significant reactive differences between hydrocarbons were identified. Carbon formation characteristics were hydrocarbon specific. The differing behavior of paraffinic and aromatic fuels with respect to their carbon formation may be important in explaining the narrow range of carbon-free operating conditions found in the ATR of number two fuel oil.
Flytzani-Stephanopoulos, M.↗
Flashback characterization of additively manufactured swirl-stabilized fuel injector with varying surface roughness
This work investigates the effects of as-built surface roughness on the flashback propensity in additively manufactured (AM) swirl-stabilized lean premixed (LPM) fuel injectors. Adoption of AM for rapid prototyping and fabrication of complex fuel-flexible injector designs requires investigating surface roughness effects on the flow and flame stability characteristics of the combustor. Wall roughness increases the near-wall shear, which could alter the boundary layer structure and change the propensity for flame flashback. Accounting for the realistic as-built surface roughness is crucial in carrying out computational modeling and experimental analysis to establish a feedback loop for the precision designing of fuel-flexible injectors. The presented numerical analysis of as-built AM injector is an essential consideration to optimize injector design for aerodynamics and additive manufacturability.
Mohanty, Pratikshya↗
Fuel penalties and time flexibility of 4D flight profiles under mismodeled wind conditions
A parametric sensitivity study was conducted to evaluate time flexibility and fuel penalties associated with 4D operations in the presence of mismodeled wind. The final cruise and descent segments of a flight in an advanced time-metered air traffic control environment were considered. Optimal performance of a B-737-100 airplane in known, constant winds was determined. Performance in mismodeled wind was obtained by tracking no-wind reference profiles in the presence of actual winds. The results of the analysis are presented in terms of loss of time flexibility and fuel penalties compared to the optimum performance in modeled winds.
Williams, David H.↗