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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Economic assessment of a multistage surface-heated vacuum membrane distillation process for the treatment of hypersaline produced water

Here, the treatment and disposal of hypersaline produced water remains a challenge, particularly for oil and gas producers in the Permian basin where production wells generate significant amounts of wastewater, and the traditional method of injecting wastewater into disposal wells is coming under increasing scrutiny. Here we investigate the viability of using solar energy to power a multi-stage, surface heated, vacuum membrane distillation (SHVMD) with energy recovery to treat hypersaline produced wastewater from Midland, Texas. Membrane distillation is a process that can desalinate waters with high total dissolved solids concentration, and when incorporated into a system with surface heating and energy recovery can achieve high water recovery rates. Model results show that a 6-stage SHVMD system with a 54.4 % water recovery rate and a gained output ratio (GOR) of 3.28 has the potential to be economically viable when used to treat hypersaline produced water in the Permian basin. Assuming energy costs of $\$0.03$/kWh thermal and $\$0.12$kWh electric , we estimate a project net present value (NPV) of $\$225,525$ and an internal rate of return (IRR) of 13.5 % when an air cooled condensor is used to cool the distillate and a NPV of $\$570,791$ and IRR of 24.52 % when a liquid coooling source is available.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

Passivated Contacts for Direct Wafer Product (Final Technical Report)

This TCF project developed a thin-oxide (SiO 2 )/polycrystalline silicon (poly-Si) passivated contact solar cell on CubicPV's (formally 1366 Technologies, Inc.) Direct Wafer® Product (DWP) kerfless wafers. The project used two NREL-developed technologies described in U.S. Patent No. 9,911,873, Hydrogenation of Passivated Contacts and U.S. Patent Application Serial No. 15/890,172, Doped Passivated Contacts . The project was motivated by a potential higher efficiency cell (compared to a PERC cell) using passivated contacts on the ultra-low cost kerfless wafers grown using the Direct Wafer process. The hope was to accelerate market adoption of the cell and wafer by delivering the lowest LCOE in the PV industry. The project tested both n-type and p-type SiO 2 /poly-Si passivated contacts grown by thermal oxidation and plasma enhanced chemical vapor deposition (PECVD) of the poly-Si layer on DWP with varying wafer resistivities. Both deposition techniques are industry standards and thus economically viable methods for commercializing the contacts. The results indicated that both n-type and p-type poly-Si passivated contacts can be formed on polycrystalline DWP wafers, but implied open-circuit voltages (i Voc ) were limited to below 0.65 mV (compared with ~ 730 mV on n-Cz wafers). Diffusion of H to the Si/SiO 2 /poly-Si interface was key to obtaining high i Voc values. In this study, H was diffused from a high-temperature SiN x layer deposited over the poly-Si layer during a high-temperature firing step, similar to one used for screen printed metals. The study concluded that poly-Si passivated contacts on DWP wafers passivated the surface of the wafers as well as PERC passivated surfaces, which use a less expensive dielectric layer stack. The project showed that Direct Wafer Product wafers grown by CubicPV could produce high i Voc values (~0.647 mV), which could produce a cell over 20% efficient with proper processing and metallization. These cells, though not economically viable in 2024 as a stand-alone cell, could be integrated with a wide-bandgap top solar cell to form a two-junction tandem cell that could be viable under certain circumstances. This is because the bottom cell of a 30%, two-terminal tandem only needs to be a 20% cell under one-sun conditions. Thus, the DWP could be an ideal low-cost wafer for tandems. The project also revealed that a TOPCon type cell could be formed on a p-type DWP wafer using a P-diffused emitter and a p-type poly-Si contact. In fact, the p-type version of the poly-Si contact out-performed the n-type version for a variety of wafer resistivities, from highly doped to lowly doped. This curiosity requires more work to understand because on Cz wafers, the n-type poly-Si contact is of much higher quality than the p-type version.

14 SOLAR ENERGY↗
DOE OSTI2021

Selective butene formation in direct ethanol-to-C3+-olefin valorization over Zn-Y/Beta and single-atom alloy composite catalysts using in situ generated hydrogen

The selective production of C3+ olefins from renewable feedstocks, especially via C1 and C2 platform chemicals, is a critical challenge for obtaining economically viable low-carbon middle distillate transportation fuels (i.e., jet and diesel). Here, we report a multifunctional catalyst system composed of Zn-Y/Beta and “single-atom” alloy (SAA) Pt-Cu/Al2O3 which selectively catalyzes ethanol-to-olefins (C3+, ETO) valorization in the absence of cofed hydrogen, forming butenes as the primary olefin products. Beta zeolites containing predominately isolated Zn and Y metal sites catalyze ethanol upgrading steps (588 K, 3.1 kPa ethanol, ambient pressure) regardless of cofed hydrogen partial pressure (0-98.3 kPa H2), forming butadiene as the primary product (60% selectivity at 87% conversion). The Zn-Y/Beta catalyst possesses site-isolated Zn and Y Lewis acid sites (at ~7 wt% Y) and Brønsted acidic Y sites, the latter of which has been previously uncharacterized. A secondary bed of SAA Pt-Cu/Al2O3 selectively hydrogenates butadiene to butene isomers at a consistent reaction temperature using hydrogen generated in situ from ethanol-to-butadiene (ETB) conversion. This unique hydrogenation reactivity at near-stoichiometric hydrogen and butadiene partial pressures is not observed over monometallic Pt or Cu catalysts, highlighting these operating conditions as a critical SAA catalyst application area for conjugated diene selective hydrogenation at high reaction temperatures (>573 K) and low H2/diene ratios (e.g., 1:1). Single-bed steady state selective hydrogenation rates, associated apparent hydrogen and butadiene reaction orders, and DFT calculations of the Horiuti-Polanyi reaction mechanisms indicate that the unique butadiene selective hydrogenation reactivity over SAA Pt-Cu/Al2O3 reflects lower hydrogen scission barriers relative to monometallic Cu surfaces and limited butene binding energies relative to monometallic Pt surfaces. DFT calculations further indicate the preferential desorption of butene isomers over SAA Pt-Cu(111) and Cu(111) surfaces while Pt(111) surface favors subsequent butene hydrogenation reactions to form butane over butene desorption events. Under operating conditions without of hydrogen cofeeding, this combination of Zn-Y/Beta and SAA Pt-Cu catalysts can selectively form butenes (65% butenes, 78% C3+ selectivity at 94% conversion) and avoid butane formation using only in situ generated hydrogen, avoiding costly hydrogen cofeeding requirements that hinder many renewable energy processes.

Cordon, Michael↗
DOE OSTI2020

Viable Materials with a Giant Magnetocaloric Effect

This review of the current state of magnetocalorics is focused on materials exhibiting a giant magnetocaloric response near room temperature. To be economically viable for industrial applications and mass production, materials should have desired useful properties at a reasonable cost and should be safe for humans and the environment during manufacturing, handling, operational use, and after disposal. The discovery of novel materials is followed by a gradual improvement of properties by compositional adjustment and thermal or mechanical treatment. Consequently, with time, good materials become inferior to the best. There are several known classes of inexpensive materials with a giant magnetocaloric effect, and the search continues. View Full-Text

36 MATERIALS SCIENCE↗
DOE OSTI2024

Electrochemical Production of Highly Valuable Carbon Nanotubes from Flue-Gas Sourced CO 2

The overarching goal of the project was to demonstrate a technology at pilot-scale that enables a net reduction in CO 2 and the production of carbon nanotubes (CNTs) with material properties comparable to commercially available CNTs at a selling price of ~80-90% less than what is available in the current market. The objectives were: (1) demonstrate the ability to utilize synthetic and real flue gas provided by a utility to produce CNTs through the SkyNano’s novel electrochemical process; (2) produce CNTs at the pilot-scale (0.2 kg/hr) using industrial flue gas that exhibit properties consistent with those available on the market today in industrial quantities, including median diameters of <30 nm, purity of at least 95% CNTs in final product, and high crystallinity (I D /I G < 1, measured via Raman spectroscopy); and (3) demonstrate the process to be sustainable and economically viable through the completion of a techno-economic analysis (TEA) and a life-cycle analysis (LCA).

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2023

The cost of direct air capture and storage can be reduced via strategic deployment but is unlikely to fall below stated cost targets

Carbon dioxide removal (CDR) is necessary to minimize the impact of climate change by tackling hard-toabate sectors and historical emissions. Direct air capture and storage (DACS) is an important CDR technology, but it remains unclear when and how DACS can be economically viable. Here, we use a bottom-up engineering-economic model together with top-down technological learning projections to calculate plant-level cost trajectories for four DACS technologies. Our analysis demonstrates that the costs of these technologies can plateau by 2050 at around $\$$100-600 t-CO 2 -1 mainly via capital cost reduction through aggressive deployment, but still exceed the optimistic targets defined by countries such as the US (i.e., $\$$100 t-CO 2 -1 ). A further analysis of existing policy mechanisms indicates that strong, project-catered policy support will be required to create market opportunities, accelerate DACS scale-up and lower the costs further. Our work suggests that strategic DACS deployment and operation must be coupled with strong policies to minimise the cost of DACS and maximise the opportunity to make a planet-scale climate impact.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2015

Enabling Parametric Optimal Ascent Trajectory Modeling During Early Phases of Design

During the early phases of engineering design, the costs committed are high, costs incurred are low, and the design freedom is high. It is well documented that decisions made in these early design phases drive the entire design's life cycle. In a traditional paradigm, key design decisions are made when little is known about the design. As the design matures, design changes become more difficult -- in both cost and schedule -- to enact. Indeed, the current capability-based paradigm that has emerged because of the constrained economic environment calls for the infusion of knowledge acquired during later design phases into earlier design phases, i.e. bring knowledge acquired during preliminary and detailed design into pre-conceptual and conceptual design. An area of critical importance to launch vehicle design is the optimization of its ascent trajectory, as the optimal trajectory will be able to take full advantage of the launch vehicle's capability to deliver a maximum amount of payload into orbit. Hence, the optimal ascent trajectory plays an important role in the vehicle's affordability posture as the need for more economically viable access to space solutions are needed in today's constrained economic environment. The problem of ascent trajectory optimization is not a new one. There are several programs that are widely used in industry that allows trajectory analysts to, based on detailed vehicle and insertion orbit parameters, determine the optimal ascent trajectory. Yet, little information is known about the launch vehicle early in the design phase - information that is required of many different disciplines in order to successfully optimize the ascent trajectory. Thus, the current paradigm of optimizing ascent trajectories involves generating point solutions for every change in a vehicle's design parameters. This is often a very tedious, manual, and time-consuming task for the analysts. Moreover, the trajectory design space is highly non-linear and multi-modal due to the interaction of various constraints. Additionally, when these obstacles are coupled with The Program to Optimize Simulated Trajectories [1] (POST), an industry standard program to optimize ascent trajectories that is difficult to use, it requires expert trajectory analysts to effectively optimize a vehicle's ascent trajectory. As it has been pointed out, the paradigm of trajectory optimization is still a very manual one because using modern computational resources on POST is still a challenging problem. The nuances and difficulties involved in correctly utilizing, and therefore automating, the program presents a large problem. In order to address these issues, the authors will discuss a methodology that has been developed. The methodology is two-fold: first, a set of heuristics will be introduced and discussed that were captured while working with expert analysts to replicate the current state-of-the-art; secondly, leveraging the power of modern computing to evaluate multiple trajectories simultaneously, and therefore, enable the exploration of the trajectory's design space early during the pre-conceptual and conceptual phases of design. When this methodology is coupled with design of experiments in order to train surrogate models, the authors were able to visualize the trajectory design space, enabling parametric optimal ascent trajectory information to be introduced with other pre-conceptual and conceptual design tools. The potential impact of this methodology's success would be a fully automated POST evaluation suite for the purpose of conceptual and preliminary design trade studies. This will enable engineers to characterize the ascent trajectory's sensitivity to design changes in an arbitrary number of dimensions and for finding settings for trajectory specific variables, which result in optimal performance for a "dialed-in" launch vehicle design. The effort described in this paper was developed for the Advanced Concepts Office [2] at NASA Marshall Space Flight Center

Holt, James B.↗
NASA NTRS1976

Design considerations of solar arrays for terrestrial applications

The primary objective of the Low-cost Silicon Solar Array (LSSA) Project, which forms a major part of a national photovoltaic program, is the timely development of low-cost commercial-quality photovoltaic arrays through an active program of industrial and academic involvement. The definition of future array requirements is considered as a necessary step toward meeting this objective. An overview of array requirement trends which begin to evolve from the various ERDA activities is presented. For present terrestrial arrays the primary requirement is to generate power for small, often remote electric-power applications. To meet an objective of increased energy independence requires that photovoltaics become economically viable for the large energy consumption of the future. Various developments needed to achieve such an economic viability are discussed.

Ross, R. G., Jr.↗
DOE OSTI2025

Integrating microbial communities into algal biotechnology: a pathway to enhanced commercialization

Microalgae are increasingly recognized for their potential in wastewater treatment and the sustainable production of feedstock for fuel, feed, food, and other bioproducts. Like conventional agricultural systems, algal cultivation involves complex microbial communities. However, despite their pivotal role in cultivation outcomes, especially at the commodity-scale, the critical interactions between microalgae and their microbiomes are often overlooked. Here we synthesize current knowledge on the taxonomic diversity, ecological roles, and biotechnological potential of algal microbiomes, with a focus on their interactions with algal hosts through nutrient exchange, growth modulation, pathogen defense, and environmental conditioning. We also examine how environmental factors such as nutrient availability, salinity, and temperature influence these interactions. Advances in microbiome engineering, including synthetic biology and ecological approaches, offer opportunities to enhance beneficial algal-microbiome interactions, thereby improving growth, resilience, and yield. These advancements could lead to more sustainable and economically viable microalgae cultivation, with far-reaching implications for environmental management and biotechnological innovation. By addressing key economic and environmental barriers, microbiome engineering holds transformative potential to revolutionize large-scale algae cultivation and provide sustainable solutions to global challenges.

Microbiology↗
DOE OSTI2024

Activity of Cannabidiol on Ex Vivo Amino Acid Fermentation by Bovine Rumen Microbiota

Amino-acid-fermenting bacteria are wasteful organisms within the rumens of beef cattle that remove dietary amino nitrogen by producing ammonia, which is then excreted renally. There are currently no on-label uses for the control of this microbial guild, but off-label use of broad-spectrum antimicrobials has shown efficacy, which contributes to antimicrobial resistance. Plant-derived antimicrobials supplemented into the diets of cattle may offer worthwhile alternatives. This study sought to investigate the role of cannabidiol (CBD) as a terpenophenolic antimicrobial. Ex vivo cell suspensions were harvested from the rumen fluid of Angus × Holstein steers in non-selective media with amino acid substrates. The suspensions were treated with five concentrations of CBD (860 μg mL−1–0.086 μg mL−1) and incubated (24 h), after which ammonia production and viable number of cells per substrate and treatment were measured. The data demonstrated a ~10–15 mM reduction in ammonia produced at the highest concentration of CBD and negligible changes in the viable number of amino-acid-fermenting bacteria. CBD does not appear to be a biologically or economically viable terpenophenolic candidate for the control of amino acid fermentation in beef cattle.

Biotechnology & Applied Microbiology↗
DOE OSTI2022

Life-Cycle and Techno-Economic Assessment of Early-Stage Carbon Capture and Utilization Technologies—A Discussion of Current Challenges and Best Practices

The mitigation of climate change requires research, development, and deployment of new technologies that are not only economically viable but also environmentally benign. Systematic and continuous technology assessment from early technology maturity onwards allows assessment practitioners to identify economic and environmental characteristics. With this information, decision-makers can focus time and resources on the most promising technologies. A broad toolset for technology assessment exists—stretching from the well-established life cycle assessment (LCA) methodology to more loosely defined techno-economic analysis (TEA) methods and the increasingly popular principles of technology maturity assessment such as the concept of technology readiness levels (TRL). However, current technology assessment practice faces various challenges at early stages, resulting in a potential mismatch of study results and stakeholders' needs and an escalation of assessment effort. In this practice review, we outline current challenges in the interplay of LCA, TEA, and TRL and present best practices for assessing early-stage climate change mitigation technologies in the field of carbon capture and utilization (CCU). The findings help practitioners systematically identify the TRL of a technology and adapt technology assessment methodologies accordingly. We highlight the methodological challenges for practitioners when adapting the goal and scope, identifying benchmark technologies, creating a comprehensive inventory, comparing early stage to commercial stage, ensuring clarity of recommendations for decision-making under high uncertainty, and streamlining conventional LCA and TEA assessment approaches and provide actionable recommendations. Overall, this work contributes to identifying promising technologies faster and more systematically, accelerating the development of new technologies for climate change mitigation and beyond.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Retrospective on Recent DOE-Funded Studies Concerning the Extraction of Rare Earth Elements & Lithium from Geothermal Brines (Final Report)

Rare earth elements (REE) and lithium are non-toxic metals that are considered critical materials due to their use in electronics, magnets, batteries, and a wide variety of industrial processes important for the economy and military preparedness. Demand for REE and lithium is increasing and these critical materials are imported, so identifying and exploiting domestic sources of REE and lithium is a national priority. The U.S. Department of Energy (DOE) Geothermal Technologies Office (GTO) has been in the forefront of sponsoring research investigating the potential recovery of REE, lithium, and other critical minerals from geothermal brines. It has been proposed that the future of geothermal energy should include “hybrid systems” that combine electricity generation with other revenue-generating activities, such as recovery of valuable and critical minerals, including REE and lithium. Two recent GTO funding opportunities have focused on the recovery of REE and other valuable minerals from geothermal brines. The research supported by the GTO’s mineral recovery program is focused on three areas: resource characterization, technology for the extraction of REE, and technology for the extraction of lithium (Tables 1 and 2). This report is a retrospective study examining the outcome of GTO’s two recent mineral recovery programs (DE-FOA-0001016 in FY 2014 and DE-FOA-0001376 in FY 2016). In this report, the knowledge, technology, and techniques that were developed by researchers funded by GTO are summarized and discussed. Four projects were funded to assess the concentrations and amounts of REE found in geothermal brines and oil field produced waters. The GTO-funded studies compiled publically available data on REE concentrations from brines and produced water from all over the USA. In addition, new samples were collected and characterized from major geothermal and hydrocarbon basins in the Western USA. The studies examined the relationship between lithology and REE concentrations and developed models examining the influence of geology on REE concentrations in produced brines. It was determined that REE are frequently found at higher concentrations in oil field produced water than geothermal brines, but that some geothermal areas had significant REE resources. Significant reservoirs of REE were identified in the Western USA. In some cases, concentrations of REE were more than 1000 times the concentrations found in seawater. Collectively, these studies represent a comprehensive picture of REE resources associated with geothermal and hydrocarbon systems in the USA. The studies did not examine lithium resources, but in some cases, lithium concentration data was collected. Data from these studies are housed in the Geothermal Data Repository (GDR) and represent a significant information resource and it is recommended that these data be further analyzed in a future study. Eight projects were funded to develop new technology for REE extraction from geothermal fluids. These projects investigated sorption as an approach for removal and recovery of REE from geothermal brines. The projects investigated cutting-edge technology for selective sorption of ions from complex solutions, including the application of metal-organic frameworks and biosorbent proteins. The REE sorption studies tested different combinations of metal-binding ligands and solid supports. The most promising metal-binding ligands for REE included phosphonic acid, thiol, and carboxylic acid functional groups. Ligands were attached or incorporated into a wide variety of solid supports. In most cases, attachment was via covalent bonding to organic resins, polymers, or silica-based supports. Most of the REE projects were conducted at a low technology readiness level (TRL) and showed promise, but direct comparison between technologies was not possible based on the available information. It is recommended that testing and reporting be standardized to the extent possible to facilitate comparisons between technologies. Two projects were directed at novel lithium extraction technology. Both projects investigated the use of inorganic sorbents, including manganese oxides. One study also examined the use of metal- ion imprinted polymers as selective ion-exchange resins for the separation of lithium and manganese from brines. Both approaches showed promise for the selective extraction of lithium from brines, including potentially geothermal brines. Results from these GTO studies indicated that selective REE and lithium extraction is possible, but interference from co-occurring solutes, such as calcium, magnesium, or heavy metals, will interfere with process efficiency and negatively impact process economics. Techno-economic analysis conducted as part of the resource and technology studies suggest extraction of REE from geothermal brines is unlikely to be economically viable, especially since non-geothermal produced waters frequently have higher REE concentrations. It is recommended that benchmarks for techno-economic analysis be established to the extent possible for future studies, to facilitate direct comparison of various technologies. Based on the collective results of this program, it appears that hybrid geothermal power would benefit more from recovery of lithium and other metals, rather than REE. It is recommended that future studies be conducted at a higher- TRL and that sorbents be tested against actual geothermal fluid samples. Prior higher-TRL efforts to extract metals from geothermal brines should be further evaluated for lessons learned.

36 MATERIALS SCIENCE↗
NASA NTRS2002

Second Generation Reusable Launch Vehicle Development and Global Competitiveness of US Space Transportation Industry: Critical Success Factors Assessment

In response to the unrelenting call in both public and private sectors fora to reduce the high cost associated with space transportation, many innovative partially or fully RLV designs (X-34-37) were initiated. This call is directed at all levels of space missions including scientific, military, and commercial and all aspects of the missions such as nonrecurring development, manufacture, launch, and operations. According to Wertz (2000), over thirty years, the cost of space access has remained exceedingly high. For example, London (1996, 1994), Wertz (1996) and Hammond (1999) have discussed in details the reasons for the skyrocket launch costs. The consensus in the popular press is that to decrease the current astronomical cost of access to space, more safer, reliable, and economically viable SGRLVs must be developed. This current skyrocket cost of space launch poses a major constraint to broadening and expanding U.S. economic activities in LEO. As a result, affecting global competitiveness of U. S. CST industry. Foreign firms control greater share of the launch market once dominated by U.S. For example, in the mid 1980s U.S. service providers had approximately 100% of the commercial space launch market revenues, but today U.S. has less than 50% of that market (Graham, 2001). Further, because of the growth potential in the international launch market, countries such as Brazil, India, Japan and Israel are gearing up to enter the global launch market with their own commercial space launch vehicles. Considering this fact, NASA and U.S. space launch industry cannot afford to lag behind. Therefore developing SGRLVs will immeasurably improve the U.S. space transportation capabilities by helping the U.S. to regain the global commercial space markets while supporting the transportation capabilities of NASA's space mission.

Chris I. Enyinda↗
NASA NTRS2006

Processing of Space Resources to Enable the Vision for Space Exploration

The NASA human exploration program as directed by the Vision for Exploration (G.W. Bush, Jan. 14,2004) includes developing methods to process materials on the Moon and beyond to enable safe and affordable human exploration. Processing space resources was first popularized (O Neill 1976) as a technically viable, economically feasible means to build city sized habitats and multi GWatt solar power satellites in Earth/Moon space. Although NASA studies found the concepts to be technically reasonable in the post Apollo era (AMES 1979), the front end costs the limits of national or corporate investment. In the last decade analysis of space on has shown it to be economically justifiable even on a relatively small mission or commercial scenario basis. The Mars Reference Mission analysis (JSC 1997) demonstrated that production of return propellant on Mars can enable an order of magnitude decrease in the costs of human Mars missions. Analysis (by M. Duke 2003) shows that production of propellant on the Moon for the Earth based satellite industries can be commercially viable after a human lunar base is established. Similar economic analysis (Rapp 2005) also shows large cost benefits for lunar propellant production for Mars missions and for the use of lunar materials for the production of photovoltaic power (Freundlich 2005). Recent technologies could enable much smaller initial costs, to achieve mass, energy, and life support self sufficiency, than were achievable in the 1970s. If the Exploration Vision program is executed with a front end emphasis on space resources, it could provide a path for human self reliance beyond Earth orbit. This path can lead to an open, non-zero-sum, future for humanity with safer human competition with limitless growth potential. This paper discusses extension of the analysis for space resource utilization, to determine the minimum systems necessary for human self sufficiency and growth off Earth. Such a approach can provide a more compelling and comprehensive path to space resource utilization.

Curreri, Peter A.↗
DOE OSTI2022

National-scale impacts on wind energy production under curtailment scenarios to reduce bat fatalities

Wind energy often plays a major role in meeting renewable energy policy objectives; however, increased deployment can raise concerns regarding the impacts of wind plants on certain wildlife. Particularly, estimates suggest hundreds of thousands of bat fatalities occur annually at wind plants across North America, with potential implications for the viability of several bat species. One approach to reducing bat fatalities is shutting down (or curtailing) turbines when bats are most at risk, such as at night during relatively low wind speed periods throughout summer and early autumn. While curtailment has consistently been shown to reduce bat fatalities, the lost power production reduces revenues for wind plants. This study conducted simulations with a range of curtailment scenarios across the contiguous United States to examine sensitivities of annual energy production (AEP) loss and potential impacts on economic metrics for future wind energy deployment. We found that AEP reduction can vary across the country from less than 1% to more than 10% for different curtailment scenarios. From an estimated 2891 gigawatts (GW) of simulated economically viable wind capacity (measured by a positive net present value), we found the mid curtailment scenario (6.0 m/s wind speed cut-in from July 1 through October 31) reduced the quantity of economic wind capacity by 274 GW or 9.5%. Our results indicate that high levels of curtailment could substantially reduce the future footprint of financially viable wind energy. In this context, future work that illuminates cost-effective strategies to minimize curtailment while reducing bat fatalities would be of value.

17 WIND ENERGY↗
NASA NTRS1974

A perspective on short-haul STOL

Discussion of the basic incentives motivating the development of the short-haul STOL air transportation system. The technological impact on the aircraft and its related economics required to achieve short field performance is generally detrimental. Considerations such as wing and empennage sizing, engine thrust sizing and cycle selection, thrust reverser requirements, cruise Mach number effects, noise, and fuel usage impacts are discussed. The direct operating economics are adversely affected, although it is thought that the indirect costs can be correspondingly reduced. A study of the total operating costs of the short-haul system and its related fare structure indicates that a definite potential exists for the evolution of an economically viable system yielding positive returns on investment to the operators. It is concluded that this potential is sufficient to warrant more detailed studies of these economics and the alternative implementation schemes.

Malthan, L. V.↗
NASA NTRS1998

Status of NASA High-Speed Research Program

This paper provides an overview of the NASA High-Speed Research (HSR) Program dedicated to establishing the technology foundation to support the US transport industry's decision for an environmentally acceptable, economically viable 300 passenger, 5000 n.mi., Mach 2.4 aircraft. The HSR program, begun in 1990, is supported by a team of US aerospace companies. The international economic stakes are high. The projected market for more than 500 High-Speed Civil Transport (HSCT) airplanes introduced between the years 2000 and 2015 translates to more than $200 billion in aircraft sales, and the potential of 140,000 new jobs. The paper addresses the history of supersonic commercial air transportation beginning with the Concorde and TU-144 developments in the early 1960 time period. The technology goals for the HSR program are derived from market study results, projections on environmental requirements, and technical goals for each discipline area referenced to the design and operational features of the Concorde. Progress since the inception of the program is reviewed and a summary of some of the lessons learned will be highlighted. An outline is presented of the remaining technological challenges. Emphasis in this paper will be on the traditional aeronautical technologies that lead to higher performance to ensure economic viability. Specific discussion will center around aerodynamic performance, flight deck research, materials and structures development and propulsion systems. The environmental barriers to the HSCT and that part of the HSR program that addresses those technologies are reviewed and assessed in a companion paper.

Allen H Whitehead Jr↗
DOE OSTI2026

Spaced out: An economic framework to explore the impacts of PV panel spacing on large-scale farming in Colorado

CONTEXT Agrivoltaic systems co-locate solar technologies with agricultural operations on an integrated plot of land and potentially provide benefits to both energy and agricultural systems. To date, large-scale (>5-MW) agrivoltaic projects in the United States have been limited to grazing and ecovoltaic applications, raising questions about the impact and scalability of agrivoltaic crop systems. Many agrivoltaic designs raise the height of the solar panels to accommodate agricultural practices while keeping energy density high. However, raising the panels results in increased photovoltaic (PV) development costs, which often are higher than the economic returns of crop production underneath the panels. This leads to unfavorable project economics and the need for other agrivoltaic solutions than raising panels. OBJECTIVE To explore other solutions, we perform an initial feasibility analysis for an agrivoltaic solution that can integrate with large-scale farming practices by increasing the row spacing in between panels. Increased PV row spacing is a low-cost approach for scaling agrivoltaics to accommodate crop production and this spacing can be tailored to required crop equipment for different regions. Increasing row spacing will reduce the power density (PV installed per acre), but in areas that are not land limited, these agrivoltaic designs could be economically feasible. Our analysis establishes a framework for a feasibility analysis for where and with what crops spaced out panel agrivoltaic solutions might be economical. METHODS Using a case study for large-scale agriculture crops in Colorado, we establish a framework for wide-row agrivoltaic economic feasibility analysis. We utilized the System Advisor Model to calculate technoeconomic metrics to compare different row spacing solutions and capture tradeoffs of these system designs. RESULTS AND CONCLUSIONS We find that, in some circumstances, wider row agrivoltaic solutions that allow for continued mechanized crop production can provide economic benefits over a traditional utility-scale PV system. For most crops examined in this analysis, roughly $\$$200/acre in agricultural profit justified spacing out the panels to at least 31.7 ft. to accommodate agrivoltaic configurations versus PV only configurations. Additionally, opportunities for increased agricultural revenue with agrivoltaic systems allow PV project economics to tolerate a larger range of CAPEX variability while remaining economically viable relative to the PV only configurations. SIGNIFICANCE This framework can be adapted for a wide variety of crops and regions and allows for examination of economically favorable sites for future agrivoltaic systems that utilize different configuration and expand opportunities for agrivoltaics.

14 SOLAR ENERGY↗