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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2024

Biodiversity loss reduces global terrestrial carbon storage

Natural ecosystems store large amounts of carbon globally, as organisms absorb carbon from the atmosphere to build large, long-lasting, or slow-decaying structures such as tree bark or root systems. An ecosystem’s carbon sequestration potential is tightly linked to its biological diversity. Yet when considering future projections, many carbon sequestration models fail to account for the role biodiversity plays in carbon storage. Here, we assess the consequences of plant biodiversity loss for carbon storage under multiple climate and land-use change scenarios. We link a macroecological model projecting changes in vascular plant richness under different scenarios with empirical data on relationships between biodiversity and biomass. We find that biodiversity declines from climate and land use change could lead to a global loss of between 7.44-103.14 PgC (global sustainability scenario) and 10.87-145.95 PgC (fossil-fueled development scenario). This indicates a self-reinforcing feedback loop, where higher levels of climate change lead to greater biodiversity loss, which in turn leads to greater carbon emissions and ultimately more climate change. Conversely, biodiversity conservation and restoration can help achieve climate change mitigation goals.

Biodiversity↗
NASA NTRS2024

Additional Aviation Sustainability Strategies

Emissions from the aviation sector are expected to grow significantly in the next few decades due to growing demand for aviation. The U.S. fleet size has increased significantly in the past 20 years, growing from 2,132 aircraft to 5,485 aircraft. Similarly from 1990 to 2019, aviation emissions more than doubled, growing faster than any other transportation mode. These emissions include carbon dioxide (CO2), as well as non-CO2 sources including nitrogen oxides (NOx), sulfur dioxide (SO2), water (H2O), and particulate matter (soot). However, this report focuses specifically on CO2 emissions because the impacts from CO2 are well-understood and long-lived. There are also many climate goals tied to CO2 emissions, including the US Aviation Climate Action Plan which is pushing for net-zero in 2050. CO2 is a greenhouse, or heat-trapping, gas that comes from the extraction and burning of fossil fuels, from wildfires, and natural processes like volcanoes. Greenhouse gases absorb heat radiating from the Earth’s surface and release it in all directions, including back toward Earth’s surface. By adding more CO2 to the atmosphere, humans amplify the natural greenhouse effect, causing global temperature to rise. Since the onset of industrial times in 1750, human activities have raised atmospheric CO2 by 50%. Considering this challenge, the United States has set a climate goal to achieve net-zero CO2 emissions in the U.S. aviation sector by 2050 to reduce the environmental impact of aviation. Net-zero emissions refers to the amount of greenhouse gases (GHGs), such as CO2, methane or SO2, that are removed from the atmosphere being equal to those emitted by human activity. This contrasts with carbon-neutrality, which refers to no net release of carbon dioxide to the atmosphere, especially through offsetting emissions, that could be accomplished through a series of actions. As of 2022, the goal of net-zero has been adopted by much of the aviation industry including multiple airlines and countries. To reach net-zero by 2050, sustainable aviation fuels (SAFs) are identified as the technology that could provide the greatest impact within this timeframe. However, certain challenges may limit the production and/or adoption of SAFs in the marketplace, such as competition for feedstocks, production capacity, and high cost. In this case, SAFs would be insufficient to meet the net-zero CO2 emission goals. Therefore, in addition to SAFs, other strategies will be needed to close the gap on emissions produced as a result of SAF shortfalls or to enhance the impact of SAFs on reducing emissions. NASA’s Aeronautics Research Mission Directorate (ARMD) aims to examine these additional pathways to explore how its research may best contribute to the realization of net-zero emissions by 2050. Specifically, this effort considers strategies that can reduce emissions in the aviation sector in combination with the use of SAFs and carbon offsets while still meeting projected passenger demand. The strategies considered are not only feasible but also could be operationally scalable by 2050. The goal of this report is to investigate additional strategies such as alternative flight and ground operations, providing insight into the CO2 emission reduction potential and feasibility of strategy implementation by 2050.

Carbon Emissions↗
NASA NTRSDate not supplied

Evaluation of Hydrolytic Degradation of Poly(lactic acid) (PLA) Matrices in Compression Molded Flax/PLA Composites

Poly(lactic acid) (PLA) is a bio-based plastic that is an attractive alternative to its petroleum-based counterparts because of its high strength and ease of thermal processing. In an effort to reduce the carbon footprint of fossil-fuel based polymer matrix composites, PLA along with naturally-occurring fibers are being explored to produce entirely bio-based replacements. Challenges in producing these composites occur due to the water affinity of the natural fibers and the susceptibility of the PLA to hydrolytic degradation. Hydrolysis of PLA occurs at elevated processing temperatures and can further be accelerated by the presence of water contained in the natural fibers. This talk will discuss the challenges and considerations associated with processing PLA in the presence of water-absorbing flax fibers to produce composites via compression molding. The thermal, physical, and mechanical properties of PLA/flax composites will be characterized at various processing times in an effort to identify optimal manufacturing conditions.

Natural Materials↗
DOE OSTI2013

Computer Modeling VRF Heat Pumps in Commercial Buildings using EnergyPlus

Variable Refrigerant Flow (VRF) heat pumps are increasingly used in commercial buildings in the United States. Monitored energy use of field installations have shown, in some cases, savings exceeding 30% compared to conventional heating, ventilating, and air-conditioning (HVAC) systems. A simulation study was conducted to identify the installation or operational characteristics that lead to energy savings for VRF systems. The study used the Department of Energy EnergyPlus? building simulation software and four reference building models. Computer simulations were performed in eight U.S. climate zones. The baseline reference HVAC system incorporated packaged single-zone direct-expansion cooling with gas heating (PSZ-AC) or variable-air-volume systems (VAV with reheat). An alternate baseline HVAC system using a heat pump (PSZ-HP) was included for some buildings to directly compare gas and electric heating results. These baseline systems were compared to a VRF heat pump model to identify differences in energy use. VRF systems combine multiple indoor units with one or more outdoor unit(s). These systems move refrigerant between the outdoor and indoor units which eliminates the need for duct work in most cases. Since many applications install duct work in unconditioned spaces, this leads to installation differences between VRF systems and conventional HVAC systems. To characterize installation differences, a duct heat gain model was included to identify the energy impacts of installing ducts in unconditioned spaces. The configuration of variable refrigerant flow heat pumps will ultimately eliminate or significantly reduce energy use due to duct heat transfer. Fan energy is also studied to identify savings associated with non-ducted VRF terminal units. VRF systems incorporate a variable-speed compressor which may lead to operational differences compared to single-speed compression systems. To characterize operational differences, the computer model performance curves used to simulate cooling operation are also evaluated. The information in this paper is intended to provide a relative difference in system energy use and compare various installation practices that can impact performance. Comparative results of VRF versus conventional HVAC systems include energy use differences due to duct location, differences in fan energy when ducts are eliminated, and differences associated with electric versus fossil fuel type heating systems.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Estimating the variable cost for high-volume and long-haul transportation of densified biomass and biofuel

This article analyzes rail transportation costs of products that have similar physical properties as densified biomass and biofuel. The results of this cost analysis are useful to understand the relationship and quantify the impact of a number of factors on rail transportation costs of denisfied biomass and biofuel. These results will be beneficial and help evaluate the economic feasibility of high-volume and long-haul transportation of biomass and biofuel. High-volume and long-haul rail transportation of biomass is a viable transportation option for biofuel plants, and for coal plants which consider biomass co-firing. Using rail optimizes costs, and optimizes greenhouse gas (GHG) emissions due to transportation. Increasing bioenergy production would consequently result in lower GHG emissions due to displacing fossil fuels. To estimate rail transportation costs we use the carload waybill data, provided by Department of Transportation’s Surface Transportation Board for products such as grain and liquid type commodities for 2009 and 2011. We used regression analysis to quantify the relationship between variable transportation unit cost ($/ton) and car type, shipment size, rail movement type, commodity type, etc. The results indicate that: (a) transportation costs for liquid is $2.26/ton–$5.45/ton higher than grain type commodity; (b) transportation costs in 2011 were $1.68/ton–$5.59/ton higher than 2009; (c) transportation costs for single car shipments are $3.6/ton–$6.68/ton higher than transportation costs for multiple car shipments of grains; (d) transportation costs for multiple car shipments are $8.9/ton and $17.15/ton higher than transportation costs for unit train shipments of grains.

09 BIOMASS FUELS↗
DOE OSTI2013

Chromatin landscaping in algae reveals novel regulation pathway for biofuels production

The diminishing reserve of fossil fuels calls for the development of biofuels. Biofuels are produced from renewable resources, including photosynthetic organisms, generating clean energy. Microalgae is one of the potential feedstock for biofuels production. It grows easily even in waste water, and poses no competition to agricultural crops for arable land. However, little is known about the algae lipid biosynthetic regulatory mechanisms. Most studies relied on the homology to other plant model organisms, in particular Arabidopsis or through low coverage expression analysis to identify key enzymes. This limits the discovery of new components in the biosynthetic pathways, particularly the genetic regulators and effort to maximize the production efficiency of algal biofuels. Here we report an unprecedented and de novo approach to dissect the algal lipid pathways through disclosing the temporal regulations of chromatin states during lipid biosynthesis. We have generated genome wide chromatin maps in chlamydomonas genome using ChIP-seq targeting 7 histone modifications and RNA polymerase II in a time-series manner throughout conditions activating lipid biosynthesis. To our surprise, the combinatory profiles of histone codes uncovered new regulatory mechanism in gene expression in algae. Coupled with matched RNA-seq data, chromatin changes revealed potential novel regulators and candidate genes involved in the activation of lipid accumulations. Genetic perturbation on these candidate regulators further demonstrated the potential to manipulate the regulatory cascade for lipid synthesis efficiency. Exploring epigenetic landscape in microalgae shown here provides powerful tools needed in improving biofuel production and new technology platform for renewable energy generation, global carbon management, and environmental survey.

09 BIOMASS FUELS↗
DOE OSTI2014

GEOCHEMICAL INVESTIGATIONS OF CO₂-BRINE-ROCK INTERACTIONS OF THE KNOX GROUP IN THE ILLINOIS BASIN

Increased output of greenhouse gases, particularly carbon dioxide (CO₂), into the atmosphere from anthropogenic sources is of great concern. A potential technology to reduce CO₂ emissions is geologic carbon sequestration. This technology is currently being evaluated in the United States and throughout the world. The geology of the Illinois Basin exhibits outstanding potential as a carbon sequestration target, as demonstrated by the ongoing Illinois Basin – Decatur Project that is using the Mt. Simon Sandstone reservoir and Eau Claire Shale seal system to store and contain 1 million tonnes of CO₂. The Knox Group-Maquoketa Shale reservoir and seal system, located stratigraphically above the Mt. Simon Sandstone-Eau Claire Shale reservoir and seal system, has little economic value as a resource for fossil fuels or as a potable water source, making it ideal as a potential carbon sequestration target. In order for a reservoir-seal system to be effective, it must be able to contain the injected CO₂ without the potential for the release of harmful contaminants liberated by the reaction between CO₂-formation fluids and reservoir and seal rocks. This study examines portions of the Knox Group (Potosi Dolomite, Gunter Sandstone, New Richmond Sandstone) and St. Peter Sandstone, and Maquoketa Shale from various locations around the Illinois Basin. A total of 14 rock and fluid samples were exposed to simulated sequestration conditions (9101–9860 kPa [1320–1430 psi] and 32°–42°C [90°– 108°F]) for varying amounts of time (6 hours to 4 months). Knox Group reservoir rocks exhibited dissolution of dolomite in the presence of CO₂ as indicated by petrographic examination, X-ray diffraction analysis, and fluid chemistry analysis. These reactions equilibrated rapidly, and geochemical modeling confirmed that these reactions reached equilibrium within the time frames of the experiments. Pre-reaction sample mineralogy and postreaction fluid geochemistry from this study suggests only limited potential for the release of United States Environmental Protection Agency regulated inorganic contaminants into potable water sources. Short-term core flood experiments further verify that the carbonate reactions occurring in Knox Group reservoir samples reach equilibrium rapidly. The core flood experiments also lend insight to pressure changes that may occur during CO₂ injection. The Maquoketa Shale experiments reveal that this rock is initially chemically reactive when in contact with CO₂ and brine. However, due to the conservative nature of silicate and clay reaction kinetics and the rapid equilibration of carbonate reactions that occur in the shale, these reactions would not present a significant risk to the competency of the shale as an effective seal rock.

Yoksoulian, Lois↗
DOE OSTI2013

The Western Wind and Solar Integration Study Phase 2 (Fact Sheet)

This fact sheet is a basic overview of the Western Wind and Solar Integration Study, Phase 2. The electric grid is a highly complex, interconnected machine, and changing one part of the grid can have consequences elsewhere. Adding wind and solar affects the operation of the other power plants and adding high penetrations can induce cycling of fossil-fueled generators. Cycling leads to wear-and-tear costs and changes in emissions.

wind, WWSIS, western wind and solar, integration, ↗
DOE OSTI2016

Supporting Clean Energy Development in Swaziland

Swaziland, a country largely dependent on regional fossil fuel imports to meet power needs, is vulnerable to supply changes and price shocks. To address this challenge, the country's National Energy Policy and Implementation Strategy prioritizes actions to enhance energy independence through scaling up renewable energy and energy efficiency. With approximately 70 percent of the country lacking electricity, Swaziland is also strongly committed to expanding energy access to support key economic and social development goals. Within this context, energy security and energy access are two foundational objectives for clean energy development in Swaziland. The partnership between the Swaziland Energy Regulatory Authority and the Clean Energy Solutions Center led to concrete outcomes to support clean energy development in Swaziland. Improving renewable energy project licensing processes will enable Swaziland to achieve key national objectives to expand clean energy access and transition to greater energy independence.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2016

Building America Case Study: Solar Water Heating in Multifamily Buildings, Greenfield, Massachusetts

Solar domestic hot water (SDHW) systems have been installed on buildings for decades, but because of relatively high costs they have not achieved significant market penetration in most of the country. As more buildings move towards zero net energy consumption, however, many designers and developers are looking more closely at SDHW. In multifamily buildings especially, SDHW may be more practical for several reasons: (1) When designing for zero net energy consumption, solar water heating may be part of the lowest cost approach to meet water heating loads. (2) Because of better scale, SDHW systems in multifamily buildings cost significantly less per dwelling than in single-family homes. (3) Many low-load buildings are moving away from fossil fuels entirely. SDHW savings are substantially greater when displacing electric resistance water heating. (4) In addition to federal tax incentives, some states have substantial financial incentives that dramatically reduce the costs (or increase the benefits) of SDHW systems in multifamily buildings. With support from the U.S. DOE Building America program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in spring of 2014, and CARB has been monitoring performance of the water heating systems since May 2014.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

NREL Collaboration Breaks 1-Volt Barrier in CdTe Solar Technology

NREL scientists have worked with Washington State University and the University of Tennessee to improve the maximum voltage available from CdTe solar cells. Changes in dopants, stoichiometry, interface design, and defect chemistry improved the CdTe conductivity and carrier lifetime by orders of magnitude, thus enabling CdTe solar cells with open-circuit voltages exceeding 1 volt for the first time. Values of current density and fill factor for CdTe solar cells are already at high levels, but sub-par voltages has been a barrier to improved efficiencies. With voltages pushed beyond 1 volt, CdTe cells have a path to produce electricity at costs less than fossil fuels.

14 SOLAR ENERGY↗
DOE OSTI2016

Building America Case Study: Solar Water Heating in Multifamily Buildings

Solar domestic hot water (SDHW) systems have been installed on buildings for decades, but because of relatively high costs they have not achieved significant market penetration in most of the country. As more buildings move towards zero net energy consumption, however, many designers and developers are looking more closely at SDHW. In multifamily buildings especially, SDHW may be more practical for several reasons: (1) When designing for zero net energy consumption, solar water heating may be part of the lowest cost approach to meet water heating loads. (2.) Because of better scale, SDHW systems in multifamily buildings cost significantly less per dwelling than in single-family homes. (3) Many low-load buildings are moving away from fossil fuels entirely. SDHW savings are substantially greater when displacing electric resistance water heating. (4) In addition to federal tax incentives, some states have substantial financial incentives that dramatically reduce the costs (or increase the benefits) of SDHW systems in multifamily buildings. With support form the U.S. DOE Building America program, the Consortium for Advanced Residential Buildings (CARB) worked with a developer in western Massachusetts to evaluate a SDHW system on a 12-unit apartment building. Olive Street Development completed construction in spring of 2014, and CARB has been monitoring performance of the water heating systems since May 2014.

Building America↗
DOE OSTI2016

From the Toilet to the Tank – Biofuels from Sewage

What we flush can be converted into a biocrude oil with properties very similar to fossil fuels. Pacific Northwest National Laboratory researchers have worked out a process that does not require that sewage be dried before transforming it under heat and pressure to biocrude. Metro Vancouver in Canada hopes to build a demonstration plant.

09 BIOMASS FUELS↗
DOE OSTI2016

R&D 100, 2016: Falling Particle Receiver

After several years of design and development, the world's first continuously recirculating high-temperature Falling Particle Receiver for Concentrated Solar Energy was constructed and tested at Sandia National Laboratories. This technology enables clean, renewable energy and electricity on demand with cheap, efficient storage at costs comparable with fossil-fuel-based plants.

14 SOLAR ENERGY↗
DOE OSTI2016

CFD Study of Full-Scale Aerobic Bioreactors: Evaluation of Dynamic O2 Distribution, Gas-Liquid Mass Transfer and Reaction

If advanced biofuels are to measurably displace fossil fuels in the near term, they will have to operate at levels of scale, efficiency, and margin unprecedented in the current biotech industry. For aerobically-grown products in particular, scale-up is complex and the practical size, cost, and operability of extremely large reactors is not well understood. Put simply, the problem of how to attain fuel-class production scales comes down to cost-effective delivery of oxygen at high mass transfer rates and low capital and operating costs. To that end, very large reactor vessels (>500 m3) are proposed in order to achieve favorable economies of scale. Additionally, techno-economic evaluation indicates that bubble-column reactors are more cost-effective than stirred-tank reactors in many low-viscosity cultures. In order to advance the design of extremely large aerobic bioreactors, we have performed computational fluid dynamics (CFD) simulations of bubble-column reactors. A multiphase Euler-Euler model is used to explicitly account for the spatial distribution of air (i.e., gas bubbles) in the reactor. Expanding on the existing bioreactor CFD literature (typically focused on the hydrodynamics of bubbly flows), our simulations include interphase mass transfer of oxygen and a simple phenomenological reaction representing the uptake and consumption of dissolved oxygen by submerged cells. The simulations reproduce the expected flow profiles, with net upward flow in the center of column and downward flow near the wall. At high simulated oxygen uptake rates (OUR), oxygen-depleted regions can be observed in the reactor. By increasing the gas flow to enhance mixing and eliminate depleted areas, a maximum oxygen transfer (OTR) rate is obtained as a function of superficial velocity. These insights regarding minimum superficial velocity and maximum reactor size are incorporated into NREL's larger techno-economic models to supplement standard reactor design equations.

09 BIOMASS FUELS↗
DOE OSTI2014

Production of biodiesel from vegetable oils; Producción de biodiesel a partir de aceites vegetales

One of the major impacts that humans have had on the world is the consequence of the use of natural resources of the planet, whose purpose has been the energy supply for economic and technological development. This economic development has caused an increase in the demand for goods and services in industrialized countries, and in turn has led to an increase in per capita consumption of energy worldwide. For this reason, it is very important to develop new energy alternatives to reduce the actual dependence on petroleum and, at the same time, reduce the impact of emissions of greenhouse gases to the environment. An alternative to using fossil fuels is biodiesel, which is biodegradable, eco-friendly, and represents an economical source of energy. Biodiesel may be produced by the transesterification reaction of new or used vegetable oils (for example sunflower, corn, or olive oil) with a short chain alcohol (methanol) in the presence of a catalyst (NaOH). In the present work we have synthesized biodiesel from these three types of vegetable oils that have been subsequently characterized. Different chemical tests have been used to ensure the quality of the biodiesel obtained. The results indicate that sunflower oil provided better efficiency biodiesel, followed by corn and olive oils. CO 2 emissions that could affect the environment were, in all cases, less than 4.1%.

09 BIOMASS FUELS↗
DOE OSTI2014

New Photocatalysts for Hydrogen Production; Nuevos Fotocatalizadores para la Producción de Hidrógeno

The use of hydrogen as replacement for fossil fuels, on which we depend today, is a matter of great relevance. The sustainable generation of hydrogen as fuel is relevant from an environmental and economic point of view. In this study we have explored new synthetic routes for developing new photocatalysts to be used in water splitting, for hydrogen production. Different techniques have been used to produce hydrogen, such as electrolysis, even though these processes have been found to be energetically non suitable. In this research various photocatalytic materials were presented as possible alternatives for using in water splitting processes. Characterization of the new synthesized materials has been done by using different experimental techniques including Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), surface area BET, and X-ray Diffraction (XRD). The efficiency of the synthesized photocatalysts was determined by evaluating the hydrogen evolution by the photocatalytic water splitting reaction.

08 HYDROGEN↗
DOE OSTI2013

Carbon Footprint of Biofuel Sugarcane Produced in Mineral and Organic Soils in Florida

Ethanol produced from sugarcane is an existing and accessible form of renewable energy. In this study, we applied the Life Cycle Assessment (LCA) approach to estimate the Carbon Footprint (CFP) of biofuel sugarcane produced on mineral (sandy) and organic (muck) soils in Florida. CFP was estimated from greenhouse gas (GHG) emissions (CO2, CH4, and N2O) during the biofuel sugarcane cultivation. The data for the energy (fossil fuels and electricity), equipment, and chemical fertilizers were taken from enterprise budgets prepared by the University of Florida based on surveys and interviews obtained from local growers during the cropping years 2007/2008 and 2009/2010 for mineral soils and 2008/2009 for organic soils. Emissions from biomass burning and organic land use were calculated based on the IPCC guidelines. The results show that the CFP for biofuel sugarcane production is 0.04 kg CO2e kg-1y-1 when produced in mineral soils and 0.46 kg CO2e kg-1y-1 when produced in organic soils. Most of the GHG emissions from production of biofuel sugarcane in mineral soils come from equipment (33%), fertilizers (28%), and biomass burning (27%); whereas GHG emissions from production in organic soils come predominantly from the soil (93%). This difference should be considered to adopt new practices for a more sustainable farming system if biofuel feedstocks are to be considered.

09 BIOMASS FUELS↗

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