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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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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Algae-based sorbents for removal of gallium from semiconductor manufacturing wastewater

Gallium is increasingly used in industry, and particularly as a component of new materials that have entered semiconductor manufacturing. The release of gallium in factory’s wastewater is potentially an environmental issue and a human health concern. Utilization of algae-based sorbents in the treatment of wastewater polluted by heavy metals has been regarded as a potentially efficient and environmentally-friendly technology. Removal of gallium from simulated wastewater using dead freshwater green algae, ( Chlorella sorokiniana ), as a sorbent was studied. Both batch and continuous flow operations were investigated. Mass balance-based process models were developed and validated for both batch and flow systems. These models were found to be valuable for both understanding the process steps as well as for analyzing the experimental data and determining the fundamental kinetics and thermodynamic parameters. Adsorption capacity was found to be 14.1 mg/g at pH of 2.3, increasing to 38.5 mg/g when the pH is raised to 2.8. The effect of pH is attributed to the surface charge interactions between biomass and gallium and indicates that gallium can be acid-washed and desorbed from the biomass. This property allows for capture followed by recovery of gallium from wastewater using algae based biosorbents.

09 BIOMASS FUELS↗
DOE OSTI2023

Muconic acid production from algae hydrolysate as a high-value co-product of an algae biorefinery

Muconic acid is an attractive bio-derived product because it can be easily converted to adipic acid, a high-value and high-volume monomer used in the production of nylon and other valuable consumer plastics. As such, production of muconic acid from algae hydrolysate was explored to expand the suite of products available from algal biomass. Here we have established initial performance parameters and have shown that the range of substrates present in algae hydrolysate that are consumed by Pseudomonas putida includes at least glucose, mannose, glycerol, acetic acid, and lactic acid. We achieved complete utilization of these major carbon sources found in Scenedesmus acutus hydrolysate with a maximum muconic acid productivity of 0.25 g/L h. Final titer was 13.0 g/L (27% molar process yield) at approximately 50 h. In addition, algae hydrolysate does not require any additional nutrients to achieve these performance metrics. Techno-economic analysis showed the potential to support up to 150 algal biorefineries at this yield with significant greenhouse gas reductions.

09 BIOMASS FUELS↗
DOE OSTI2011

The GC-rich mitochondrial and plastid genomes of the green alga Coccomyxa give insight into the evolution of organelle DNA nucleotide landscape

Here, most of the available mitochondrial and plastid genome sequences are biased towards adenine and thymine (AT) over guanine and cytosine (GC). Examples of GC-rich organelle DNAs are limited to a small but eclectic list of species, including certain green algae. Here, to gain insight in the evolution of organelle nucleotide landscape, we present the GC-rich mitochondrial and plastid DNAs from the trebouxiophyte green alga Coccomyxa sp. C-169. We compare these sequences with other GC-rich organelle DNAs and argue that the forces biasing them towards G and C are nonadaptive and linked to the metabolic and/or life history features of this species. The Coccomyxa organelle genomes are also used for phylogenetic analyses, which highlight the complexities in trying to resolve the interrelationships among the core chlorophyte green algae, but ultimately favour a sister relationship between the Ulvophyceae and Chlorophyceae, with the Trebouxiophyceae branching at the base of the chlorophyte crown.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Model of temperature, evaporation, and productivity in elevated experimental algae raceways and comparison with commercial raceways

Elevated Experimental Raceways (EERs) have been used at many research sites in the United States to evaluate algal biomass productivity. This paper develops temperature and evaporation models for EERs and then evaluates whether the temperature profile and resultant productivity in an EER is representative of large-scale commercial raceways. Open water surface evaporation and temperature models with shading algorithms were programmed in Python and calibrated with temperature and evaporation data from the EERs in the Regional Algal Feedstock Testbed (RAFT) experiments at the University of Arizona. The final calibrated model for EERs was named the EERTEM (Elevated Experimental Raceway Temperature and Evaporation Model). The energy balance algorithms in the Biomass Assessment Tool (BAT model) were also added to the Python code and used to develop temperature simulations of standard commercial paddlewheel raceways. A comparison of BAT and EERTEM simulations indicated that EER temperature fluctuations are not representative of in ground commercial paddlewheel raceways, primarily due to the buffering effect of soil heat flux in commercial raceways. With the different temperature profiles, biomass productivities of three algae species in the EERs were compared to productivities in commercial raceways. Differences in productivity between EERTEM and BAT model temperature profiles were observed when the maximum daytime temperature of one raceway was in the optimal growth range but the temperature of the other raceway exceeded or was below the optimal growth range.

Khawam, George↗
DOE OSTI2014

Spectroradiometric monitoring for open outdoor culturing of algae and cyanobacteria

We assess the measurement of hyperspectral reflectance for the outdoor monitoring of green algae and cyanobacteria cultures with a multi-channel, fiber-coupled spectroradiometer. Reflectance data acquired over a four-week period are interpreted via numerical inversion of a reflectance model, in which the above-water reflectance is expressed as a quadratic function of the single backscattering albedo, dependent on the absorption and backscatter coefficients. The absorption coefficient is treated as the sum of component spectra consisting of the cultured species (green algae or cyanobacteria), dissolved organic matter, and water (including the temperature dependence of the water absorption spectrum). The backscatter coefficient is approximated as the scaled Hilbert transform of the culture absorption spectrum with a wavelength-independent vertical offset. Additional terms in the reflectance model account for the pigment fluorescence features and the water surface reflection of sunlight and skylight. For both the green algae and cyanobacteria, the wavelength-independent vertical offset of the backscatter coefficient is found to scale linearly with daily dry weight measurements, providing the capability for a non-sampling measurement of biomass in outdoor ponds. Other fitting parameters in the reflectance model are compared to auxiliary measurements and physics-based calculations. The magnitudes of the sunlight and skylight water-surface contributions derived from the reflectance model compare favorably with Fresnel reflectance calculations, while the reflectance-derived quantum efficiency of Chl-a fluorescence is found to be in agreement with literature values. To conlclude, the water temperature derived from the reflectance model exhibits excellent agreement with thermocouple measurements during the morning hours and highlights significantly elevated temperatures in the afternoon hours.

47 OTHER INSTRUMENTATION↗
DOE OSTI2018

A model suite of green algae within the Scenedesmaceae for investigating contrasting desiccation tolerance and morphology

ABSTRACT Microscopic green algae inhabiting desert microbiotic crusts are remarkably diverse phylogenetically, and many desert lineages have independently evolved from aquatic ancestors. Here we worked with five desert and aquatic species within the family Scenedesmaceae to examine mechanisms that underlie desiccation tolerance and release of unicellular versus multicellular progeny. Live cell staining and time-lapse confocal imaging coupled with transmission electron microscopy established that the desert and aquatic species all divide by multiple (rather than binary) fission, although progeny were unicellular in three species and multicellular (joined in a sheet-like coenobium) in two. During division, Golgi complexes were localized near nuclei, and all species exhibited dynamic rotation of the daughter cell mass within the mother cell wall at cytokinesis. Differential desiccation tolerance across the five species, assessed from photosynthetic efficiency during desiccation/rehydration cycles, was accompanied by differential accumulation of intracellular reactive oxygen species (ROS) detected using a dye sensitive to intracellular ROS. Further comparative investigation will aim to understand the genetic, ultrastructural and physiological characteristics supporting unicellular versus multicellular coenobial morphology, and the ability of representatives in the Scenedesmaceae to colonize ecologically diverse, even extreme, habitats.

Cardon, Zoe G. (ORCID:0000000187257842)↗
DOE OSTI2017

The laboratory environmental algae pond simulator (LEAPS) photobioreactor: Validation using outdoor pond cultures of Chlorella sorokiniana and Nannochloropsis salina

A bench-scale photobioreactor system, the Laboratory Environmental Algae Pond Simulator (LEAPS), was designed and constructed to simulate outdoor pond cultivation for a wide range of geographical locations and seasons. The LEAPS consists of six well-mixed glass column photobioreactors submerged in a temperature controlled waterbath (-2 °C to >60 °C) and illuminated from above by a programmable multicolor LED lighting system (0 to 2,500 µmol/m 2 -sec). Measured incident light intensities and water temperatures deviated from the respective light and temperature setpoints on average only 2.3% and 0.9%, demonstrating accurate simulation of light and temperature conditions measured in outdoor ponds. In order to determine whether microalgae strains cultured in the LEAPS exhibit the same linear phase biomass productivity as in outdoor ponds, Chlorella sorokiniana and Nannochloropsis salina were cultured in the LEAPS bioreactors using light and temperature scripts measured previously in the respective outdoor pond studies. For Chlorella sorokiniana, the summer season biomass productivity in the LEAPS was 6.6% and 11.3% lower than in the respective outdoor ponds in Rimrock, Arizona, and Delhi, California; however, these differences were not statistically significant. For Nannochloropsis salina, the winter season biomass productivity in the LEAPS was 9.2% higher than in the respective outdoor ponds in Tucson, Arizona, a difference shown to be not statistically significant. Potential reasons for the positive or negative divergence in LEAPS performance, relative to outdoor ponds, are discussed. To demonstrate the utility of the LEAPS in predicting productivity, two other strains – Scenedesmus obliquus and Stichococcus minor – were evaluated using the summer season script for Rimrock, Arizona. For both strains, the productivity was around 11.6 g/m 2 -day at 25 cm culture depth. In conclusion, the LEAPS is an accurate pond simulator and thus offers a reliable, fast, and cost-effective way to screen microalgae strains and operating conditions for high biomass productivity and co-product yields.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Chromosome-level genome assembly and transcriptome of the green alga Chromochloris zofingiensis illuminates astaxanthin production

Microalgae have potential to help meet energy and food demands without exacerbating environmental problems. There is interest in the unicellular green alga Chromochloris zofingiensis, because it produces lipids for biofuels and a highly valuable carotenoid nutraceutical, astaxanthin. Here, to advance understanding of its biology and facilitate commercial development, we present a C. zofingiensis chromosome-level nuclear genome, organelle genomes, and transcriptome from diverse growth conditions. The assembly, derived from a combination of short- and long-read sequencing in conjunction with optical mapping, revealed a compact genome of ~58 Mbp distributed over 19 chromosomes containing 15,274 predicted protein-coding genes. The genome has uniform gene density over chromosomes, low repetitive sequence content (~6%), and a high fraction of protein-coding sequence (~39%) with relatively long coding exons and few coding introns. Functional annotation of gene models identified orthologous families for the majority (~73%) of genes. Synteny analysis uncovered localized but scrambled blocks of genes in putative orthologous relationships with other green algae. Two genes encoding beta-ketolase (BKT), the key enzyme synthesizing astaxanthin, were found in the genome, and both were up-regulated by high light. Isolation and molecular analysis of astaxanthin-deficient mutants showed that BKT1 is required for the production of astaxanthin. Moreover, the transcriptome under high light exposure revealed candidate genes that could be involved in critical yet missing steps of astaxanthin biosynthesis, including ABC transporters, cytochrome P450 enzymes, and an acyltransferase. Finally, the high-quality genome and transcriptome provide insight into the green algal lineage and carotenoid production.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2016

Use of Cultivation Data from the Algae Testbed Public Private Partnership as Utilized in NREL's Algae State of Technology Assessments

The Algae Testbed Public Private Partnership (ATP3) conducted algal growth experiments over the course of 16 months termed the Unified Field Studies (UFS). These experiments were conducted at 5 different geographic locations in Arizona (ASU), California (CP), Florida (FA), Georgia (GT), and Hawaii (CELL). The UFS sought to evaluate different algal biomass harvesting strategies using identical ponds, media, and operational conditions through all four seasons across different geographic regions to isolate the effects on productivity attributed to locational climate and seasonal variability, overlaid by the differing harvest strategies. Set up as the baseline against which other experiments would build upon, it must be emphasized that as per the stated, approved experimental goals of the ATP3 UFS, no attempts at growth or lipid accumulation optimization were made; rather, the primary focus of the UFS work was to cultivate algal biomass under deliberate, consistent conditions, time periods, and harvesting protocols, to provide public data on year-round outdoor biomass production that could be directly compared between one site and another (with accompanying climate data for each site). Thus the resulting productivity numbers in effect represent a conservative baseline of non-optimized algal growth one may expect at these sites. Also clearly weather can vary dramatically from season to season and from year to year, and even within a given 'season' where an individual season's data was typically based on 4-6 week operating windows. Thus these numbers also only reflect a short snapshot in time, and must be interpreted carefully in projecting what may be expected over many years or decades (for example, a 30-year facility lifetime as evaluated in techno-economic models).

09 BIOMASS FUELS↗
DOE OSTI2021

Techno-economic and Life Cycle Analysis of MixAlco® Processes for Mixed Alcohol Production from Brown Algae

The need for producing renewable fuels from biomass has increased due to depleting fossil resources and environmental concerns. However, the low fraction of biomass carbon converted to product is an undeniable drawback for most current biofuel productions from fermentation due to undecomposed lignin in biomass composition and carbon loss as CO 2 . In this work, two main production routes of the MixAlco® process, the ketonization route (KR) and esterification route (ER) are evaluated for the mixed alcohol production by brown algae, a third-generation biomass without lignin. A novel fermentation process using syntrophic bacteria consortia (SBC) is developed to produce acetic acid from waste gas produced by KR and ER process. The paper investigates the integrated flowsheet for these alternative routes, using techno-economic and life cycle analysis to compare the minimum selling price and environmental impacts. From TEA, we find that the overall costs for KR and ER are lower than the SBC processes. The cost of ketonization routes is lower than esterification routes. The capital cost and operating cost for the ER+SBC process are the highest. Raw materials and utilities are the two major costs for all the processing routes examined. Here, the MSP for the ER+SBC process is the lowest out of all four routes. ER process performs the best in terms of environmental impacts except in water depletion compared with other processes, while the KR process performs the worst regarding the environmental metrics.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Air Carbon for Algae Production (AirCAP) – Expanding algae resource potential via direct (in-pond) air-CO2 capture.

Microalgae biofuel production potential in the United States is constrained by a lack of suitable cultivation locations within a close proximity to CO2 point-sources. Initial estimates suggest that removing the requirement of a concentrated CO2 source expands resource potential ten-fold, allowing the projection of production levels that approach levels of current U.S. diesel consumption. Decoupling cultivation locations from concentrated CO2 point-sources requires direct capture of air-CO2 into the pond bulk at a rate sufficient to meet maximum expected carbon assimilation rates (10 g C/m2-day and higher). Enhancement of the ingassing rate via chemical reaction, the direct reaction of dissolved CO2 with hydroxide ions, has been proposed as a mechanism to increase the ingassing rate of air-CO2. The central objectives of this project are to validate whether chemically enhanced air-CO2 ingassing rates in large raceway ponds can meet or exceed the level required to support high levels of algae productivity, then subsequently identify alkaliphilic strains able to withstand such conditions while maintaining a biomass productivity that enables process economics. Full scale ponds (~1 acre, unlined) will be used to validate ingassing rates as a function of pH expected at scale in a series of abiotic experiments. To date, mass-transfer dynamics have been characterized in ponds ranging from 1 to 1,000 m2. Initial results will be presented describing the mass transfer coefficient in 1-acre (~4,000 m2), unlined ponds. The maximum expected carbon ingassing rate will be measured during ingassing trials, in which pond pH is displaced from equilibrium via the addition of a strong base, with the subsequent decrease in pH (and increase in dissolved inorganic carbon) corresponding to the air-CO2 absorption rate. A mass-transfer model, validated with experimental results, will be used to project ingassing rates expected at pond scales (10 acres) required for production of commodity chemicals.

09 BIOMASS FUELS↗
DOE OSTI2015

Simultaneous cryo X-ray ptychographic and fluorescence microscopy of green algae

Trace metals play important roles in normal and in disease-causing biological functions. X-ray fluorescence microscopy reveals trace elements with no dependence on binding affinities (unlike with visible light fluorophores) and with improved sensitivity relative to electron probes. However, X-ray fluorescence is not very sensitive for showing the light elements that comprise the majority of cellular material. Here we show that X-ray ptychography can be combined with fluorescence to image both cellular structure and trace element distribution in frozen-hydrated cells at cryogenic temperatures, with high structural and chemical fidelity. Ptychographic reconstruction algorithms deliver phase and absorption contrast images at a resolution beyond that of the illuminating lens or beam size. Using 5.2-keV X-rays, we have obtained sub-30-nm resolution structural images and similar to 90-nm-resolution fluorescence images of several elements in frozen-hydrated green algae. This combined approach offers a way to study the role of trace elements in their structural context.

Deng, Junjing↗
DOE OSTI2022

BETO 2021 Peer Review: Algae Biotechnology Partnership - Technology Area Session: Advanced Algae Systems

Development of advanced genetic and genomic tools for targeted algal metabolic engineering pursuits will be integral to achieving target biomass productivity and, ultimately, the BETO goal of cost-competitive biofuels derived from algal biomass by 2022. However, at present, broad-host-range tool development is currently hindered by strain-specific negative regulatory mechanisms. Indeed, the biological processes controlling algal transcription and translation are subject to complex host regulation, which often presents hurdles for targeted genetic engineering strategies. Advanced genetic approaches offer a means to rewire these regulatory systems and/or introduce novel functionality into algal biocatalysts. Synthetic systems biology approaches also present a means to construct novel genetic regulatory networks and rewire natural biological systems to establish an “orthogonal central dogma,” wherein non-native control elements are introduced into or evolved in host microbes for bypass of host control. To this end, the Algae Biotechnology Partnership aims to develop advanced genetic editing tools and synthetic and orthogonal genetic regulatory systems to enable universal metabolic engineering strategies in top-candidate deployment algal strains. Successful development will ultimately open the door for targeted strain-engineering strategies, aimed at maximizing algal outdoor biomass production, composition, and strain robustness.

biocatalysis↗