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At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Crop protection in algae by exogenous terpene expression

The present disclosure relates to terpene synthases capable of producing terpenoids. In one instance, a transformed organism can include terpene synthases or vectors encoding such synthases. One method of employing such synthases and organisms includes protecting an algal culture, in which the produced terpenoid can act as a biocide.

Davis, Ryan Wesley↗
DOE OSTI2020

Preservation of Microalgae, Lignocellulosic Biomass Blends by Ensiling to Enable Consistent Year-Round Feedstock Supply for Thermochemical Conversion to Biofuels

Seasonal variation in microalgae productivity is a significant barrier to economical production of algae biofuels and chemicals. Summer production can be 3–5 times higher than in the winter resulting in uneven feedstock supplies at algae biorefineries. A portion of the summer production must be preserved for conversion in the winter in order to maintain a biorefinery running at capacity. Ensiling, a preservation process that utilizes lactic acid fermentation to limit microbial degradation, has been demonstrated to successfully stabilize algae biomass (20% solids) and algae-lignocellulosic blends (40% algae-60% lignocellulosic biomass, dry basis) for over 6 months, resulting in fuel production cost savings with fewer emissions. Preservation of algae as blends could be beneficial to biorefineries that utilize thermochemical approaches to fuel production as co-processing of algae and lignocellulosic biomass has been observed to enhance biocrude yield and improve oil quality. This study conducts a resource assessment of biomass residues in the southern United States to identify materials available during peak algae productivity and in sufficient quantity to meet the algae storage needs of an algae biofuel industry. Eight feedstocks met the quantity threshold but only three, distillers grains, haylage, and yard waste, were also available in season. Storage experiments utilizing both freshwater and marine strains of microalgae – Scenedesmus acutus, Chlorella vulgaris, Chlorella zofingiensis, Nannochloropsis gaditana, and Porphyridium purpureum – and yard waste were conducted for 30 days. Storage losses were less than 10% in all but one case, and the pH of all but one blend was reduced to less than 4.7, indicating that yard waste is a suitable feedstock for blending with algae prior to storage. To better understand whether the benefits to conversion realized by processing blends might be affected by storage, elemental analysis and bomb calorimetry of pre- and post-storage algae-yard waste blends were conducted to characterize changes occurring during storage. Storing algae biomass as blends with lignocellulosic biomass could be an effective method of mitigating seasonal variability in algae biomass production while retaining the synergistic effect of co-processing algae blends in thermochemical conversion.

09 BIOMASS FUELS↗
DOE OSTI2015

Pt-based Bi-metallic Monolith Catalysts for Partial Upgrading of Microalgae Oil

Valicor’s proprietary wet extraction process in conjunction with thermochemical pre-treatment was performed on algal biomass from two different algae strains, Nannochloropsis Salina (N.S.) and Chlorella to produce algae oils. Polar lipids such as phospholipids were hydrolyzed, and metals and metalloids, known catalyst poisons, were separated into the aqueous phase, creating an attractive “pre-refined” oil for hydrodeoxygenation (HDO) upgrading by Stevens. Oil content and oil extraction efficiency of approximately 30 and 90% respectively were achieved. At Stevens, we formulated a Pt-based bi-metallic catalyst which was demonstrated to be effective in the hydro-treating of the algae oils to produce ‘green’ diesel. The bi-metallic catalyst was wash-coated on a monolith, and in conjunction with a high throughput high pressure (pilot plant) reactor system, was used in hydrotreating algae oils from N.S. and Chlorella. Mixtures of these algae oils and refinery light atmospheric gas oil (LAGO) supplied by our petroleum refiner partner, Marathon Petroleum Corporation, were co-processed in the pilot plant reactor system using the Pt-based bi-metallic monolith catalyst. A 26 wt% N.S. algae oil/74 wt % LAGO mixture hydrotreated in the reactor system was subjected to the ASTM D975 Diesel Fuel Specification Test and it met all the important requirements, including a cetane index of 50.5. An elemental oxygen analysis performed by an independent and reputable lab reported an oxygen content of trace to none found. The successful co-processing of a mixture of algae oil and LAGO will enable integration of algae oil as a refinery feedstock which is one of the goals of DOE-BETO. We have presented experimental data that show that our precious metal-based catalysts consume less hydrogen than the conventional hydrotreating catalyst NiMo Precious metal catalysts favor the hydrodecarbonylation/hydrodecarboxylation route of HDO over the dehydration route preferred by base metal catalysts, and consumes less hydrogen, if methanation can be mitigated. Our methanation data on Pt and Rh indicate effective suppression of methanation. Our data also show that our catalysts are less susceptible to coking; and unlike NiMo and CoMo, precious metal catalysts are not deactivated by water, a by-product of HDO of algae oil. Finally, our catalysts do not need to be sulfided to be active. A rigorous techno-economic analysis of our process for commercial scale production of 10,000 barrels per day of hydrotreated algae oil, with nutraceuticals co-product claiming only 0.05% of the raw algae oil, indicates an estimated plant gate price of ~$10/gal. Sensitivity analysis shows that critical parameters affecting sale price include (1) algae doubling time (2) biomass oil content (3) CAPEX, and (4) moisture content of post extracted algae residue. Modest improvements in these areas will result in enhanced and competitive economics. Based on a life cycle assessment for greenhouse gas emission, we found that if algae oil replaced 10% of the US consumption, this would result in a CO2e reduction of 210,000 tons per day. Improving the drying process for animal feed by 50% would result in further significant reduction in CO2e.

09 BIOMASS FUELS↗
NASA NTRS2015

Benefits of Microalgae for Human Space Exploration

Algae have long been known to offer a number of benefits to support long duration human space exploration. Algae contain proteins, essential amino acids, vitamins, and lipids needed for human consumption, and can be produced using waste streams, while consuming carbon dioxide, and producing oxygen. In comparison with higher plants, algae have higher growth rates, fewer environmental requirements, produce far less "waste" tissue, and are resistant to digestion and/or biodegradation. As an additional benefit, algae produce many components (fatty acids, H2, etc.) which are useful as biofuels. On Earth, micro-algae survive in many harsh environments including low humidity, extremes in temperature, pH, and as well as high salinity and solar radiation. Algae have been shown to survive inmicro-gravity, and can adapt to high and low light intensity while retaining their ability to perform nitrogen fixation and photosynthesis. Studies have demonstrated that some algae are resistant to the space radiation environment, including solar ultraviolet radiation. It remains to be experimentally demonstrated, however, that an algal-based system could fulfil the requirements for a space-based Bioregenerative Life Support System (BLSS) under comparable spaceflight power, mass, and environmental constraints. Two specific challenges facing algae cultivation in space are that (i) conventional growth platforms require large masses of water, which in turn require a large amount of propulsion fuel, and (ii) most nutrient delivery mechanisms (predominantly bubbling) are dependent on gravity. To address these challenges, we have constructed a low water biofilm based bioreactor whose operation is enabled by capillary forces. Preliminary characterization of this Surface Adhering BioReactor (SABR) suggests that it can serve as a platform for cultivating algae in space which requires about 10 times less mass than conventional reactors without sacrificing growth rate. Further work is necessary to compare the performance of microalgae-based systems, including SABR, with systems based on higher plants, as well as conventional physicochemical-based systems. Ongoing and future work in our laboratory is therefore directed determining the feasibility of using algae as a component of a BLSS in space.

Algae↗
DOE OSTI2020

Insights into community of photosynthetic microorganisms from permafrost

ABSTRACT This work integrates cultivation studies of Siberian permafrost and analyses of metagenomes from different locations in the Arctic with the aim of obtaining insights into the community of photosynthetic microorganisms in perennially frozen deposits. Cyanobacteria and microalgae have been described in Arctic aquatic and surface soil environments, but their diversity and ability to withstand harsh conditions within the permafrost are still largely unknown. Community structure of photosynthetic organisms in permafrost sediments was explored using Arctic metagenomes available through the MG-RAST. Sequences affiliated with cyanobacteria represented from 0.25 to 3.03% of total sequences, followed by sequences affiliated with Streptophyta (algae and vascular plants) 0.01–0.45% and Chlorophyta (green algae) 0.01–0.1%. Enrichment and cultivation approaches revealed that cyanobacteria and green algae survive in permafrost and they could be revived during prolonged incubation at low light intensity. Among photosynthetic microorganisms isolated from permafrost, the filamentous Oscillatoria-like cyanobacteria and unicellular green algae of the genus Chlorella were dominant. Our findings suggest that permafrost cyanobacteria and green algae are expected to be effective members of the re-assembled community after permafrost thawing and soil collapse.

Vishnivetskaya, Tatiana A.↗
DOE OSTI2019

Simulation of shading and algal growth in experimental raceways

Many algae research groups use elevated experimental raceways to characterize algal biomass productivity. Side walls and a relatively large paddlewheel shade the culture and lower productivity, particularly in winter and with low culture depth. This paper presents a methodology to calculate shading for a given raceway shape: (1) develop a mesh of the inner surface geometry of the raceway; (2) offset the mesh horizontally in the x and y directions on the water surface as a function of wall height, solar zenith angle, and solar azimuth angle; (3) calculate the shaded area for each projected mesh with the shoelace algorithm; (4) use regression to develop a response surface for shaded area as a function of horizontal x and y offset. For each time step, the shaded area is calculated with the regression equation based on the x and y offset at that time step. The shading model was added to the Huesemann Algae Biomass Growth (HABG) model, which predicts algae growth rate as a function of water temperature and light intensity in algae culture layers. The shading model was evaluated with biomass concentrations from three Regional Algal Feedstock Testbed (RAFT) experiments with three different species of algae. The shading algorithm reduced the HABG estimate of productivity and improved the agreement with observed productivities. In the model, productivity was sensitive to the assumed light distribution below the water surface. Averaging light in each layer resulted in higher calculated growth rate than calculating growth separately in shaded and unshaded areas. Shaded area was sensitive to raceway orientation, water depth, and time of year. A north-south raceway orientation had less average shading in winter but more average shading in summer than an east-west orientation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Managing weather- and market price-related financial risks in algal biofuel production

Large-scale algae production has garnered interest due to its potential as a biofuel feedstock. Previous research assessing the profitability of algae products has been mostly based on values averaged over time, but algae production and resulting financial returns exhibit significant variability due to weather and fluctuations in selling prices for algae-based products. In other sectors, producers often reduce weather- and market price-related financial risk with financial instruments such as insurance, but little research has been performed on the design of insurance products to protect algae producers. Furthermore, this study develops a novel index-based insurance instrument that pays-out during unfavorable weather and market conditions, then explores the instrument's effectiveness, combined with a cash reserve, in reducing revenue stream variability for an algae producer. Results indicate that a biophysically based index-insurance product tailored to the specific financial risks in algae production can reduce variability in net revenues and can do so at a lower cost than relying solely on cash reserves, the most common financial risk management tool. Assessing the performance of index-insurance in algae production is particularly timely given the passage of the 2018 Farm Bill, which newly opens opportunities for the USDA to provide crop insurance to algae producers.

09 BIOMASS FUELS↗
DOE OSTI2018

Microalgae Commodities from Coal-Fired Power Plant Flue Gas CO 2 (Draft Final Report, October 1, 2015 to June 30, 2018)

The Orlando Utilities Commission (OUC) operates an approximately 900-MWe coal fired-power plant at Stanton Energy Center (SEC), which was the site for this project to develop an integrated process for microalgae utilization of flue gas CO 2 for the production of biofuels and animal feeds. Microalgae have both potentially high yields (tons biomass/acre-year) and can be used for biofuels or high value animal feeds. The high biomass yields of microalgae cultures allows efficient use of land and water resources. They can also use wastewaters, recycle fertilizers, and have lower overall greenhouse gas emissions than conventional biofuels or animal feeds. However, many technical issues and technology gaps related to large-scale algae biomass production still must be resolved before such a process can be scaled-up. In this project, techno-economic analyses (TEAs) and life cycle assessments (LCAs) were carried out, projecting the costs and impacts of large-scale algae biomass cultivation for production of biofuels and animal feeds using OUC-SEC flue gas CO 2 . In addition, 3.5-m 2 (~ 40-ft 2 ) experimental raceway ponds were used for the cultivation of microalgae at OUC-SEC and also at the University of Florida. A large-scale algae farm was designed for a 1,300-acre site (~500-ha) located near the OUC-SEC plant, consisting of 400 hectares (1,000 acres) of paddle wheel mixed raceway ponds (each 4 ha), receiving flue gas piped approximately 3 km (2 miles) from the SEC plant. In the first year of this project (Budget Period 1, BP1), the TEA and LCA studies focused on the production of biogas produced from algae biomass and its use to replace coal at the power plant. However, due to the resulting very high cost of CO 2 mitigation, the process was modified to produce compressed natural gas (‘renewable natural gas’, RNG) for transportation fuel from the biogas, in conjunction with wastewater treatment by the algae cultures. During Budget Period 2 (BP2), the TEA and LCA studies focused on the production of animal feeds by the algae farm, using fresh water and agricultural fertilizers. In this case, CO 2 mitigation costs would be entirely covered if the algal biomass could be sold at between a two to three-fold premium above soybean feed, based on a higher nutritional value for the algal biomass. In support of the above analyses, microalgae cultivation experiments were carried out for over two years during this project in small 3.5-m 2 ponds at both SEC and the University of Florida. The most important results were the demonstration at SEC of the cultivation, on flue gas CO 2 , of filamentous algae biomass, which can be harvested at much lower cost than processes required for the colloidal algae species, as currently used by almost all algal mass culture biofuels and animal feeds projects. The yield of biogas production from the algal biomass was investigated by the University of Florida, and the value of the algal biomass as animal feed was projected based on biochemical analysis of the SEC ad UF biomasses. The conclusion from TEA/LCA carried out for the biogas case in BP1 was that a 400-ha algae system producing biomethane for co-firing at OUC-SEC could generate 27,500 MWh/yr of renewable power, offsetting 28,400 Mg CO 2eq /yr, which amounted to less than 1% of the CO 2 emitted by the SEC plant. (Mg = metric ton = 1.10 short tons). The overall cost was projected at $820/Mg of CO 2eq reduction, making this process unfeasible under any possible scenario. More favorable economics were projected when the biogas was converted to higher value transportation fuel, RNG, which also would benefit from renewable fuel (RINs) and possibly other credits. However, only by combining RNG production with municipal wastewater treatment in the algal ponds would CO 2 utilization result in no net cost or even be economically beneficial (i.e., generate income to the power plant). However, in that case the amount of CO 2 utilization would be even lower than that in the biogas case, because a large fraction of the carbon required would be supplied from the wastewater and CO 2 recovered during biogas upgrading to RNG. In brief, use of power plant CO 2 emissions for algal biofuels production was not favorable, even with optimistic assumptions about biomass productivity and biogas yields. For the animal feed case, developed during BP2, algal biomass would replace soybean feeds. The same scale 400-ha algal production plant was projected to produce 26,280 Mg per year of animal feed with a utilization of 45,300 Mg flue gas CO 2 taken up by the algal biomass. However, the process would result in a projected reduction of 112,500 Mg CO 2eq emissions per year, or roughly 1.9% of OUC-SEC emissions, mainly due to the large CO 2eq emissions from conventional soybean production. A major factor in this analysis were greenhouse gas emissions from land use changes. The cost of CO 2 utilization was projected at $116/Mg if the biomass sold for the same price as soybean meal, but if sold as a premium feed (e.g., based on high omega-3 fatty acid and carotenoid content), the power plant could actually charge for the CO 2 utilized. These economic projections are sensitive to assumptions underlying the TEA and LCA models, including biomass composition and the financial models used to project CAPEX and OPEX. Further development of an algal animal feed production using coal-fired power plant flue gas CO 2 is recommended based on the TEA and LCA, as well as experimental results. The required research and development is detailed in a technology gap analysis (Section 11), which focuses on the demonstrations of the cultivation of higher value filamentous algal biomass at OUC-SEC.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2021

Development of Algal Biomass Yield Improvements in an Integrated Process (Final Report)

This project built on the success of Global Algae Innovations Algae Biomass Yield Phase 1 project to accelerate the commercialization of algal biofuels through development of an integrated, economical, photosynthetic, open raceway system to produce algal oil. Two parallel pathways to a biofuel were investigated. In the algal crude oil pathway, highlighted in blue, the dewatered algal biomass slurry is used as a feed to hydrothermal liquefaction to produce an algae crude oil and recycle aqueous stream. In the algal lipid oil pathway, highlighted in green, the algal biomass slurry is dried, and the oil is extracted to produce an algal lipid oil biofuel intermediate and a high protein algae meal co-product. Upgrading to drop-in fuels has been demonstrated for the biofuel intermediates in both pathways. Since the algal lipid oil pathway requires lipid accumulation, the productivity is generally lower than the algal crude oil pathway, but the required productivity for economical algal biofuel production is also lower because the coproduct value is greater. The outdoor cultivation was performed at the Kauai Algae Farm. The project team has expertise across the full breadth strain development, advanced algal cultivation, open raceway contamination control, CO 2 supply, harvesting, dewatering, extraction, hydrothermal liquefaction, technoeconomic analysis and life cycle analysis: Hildebrand laboratory at Scripps Institution of Oceanography – diatom strain development. Mayfield laboratory at UCSD - green algae strain development. TSD Management Associates- CO 2 supply, algal harvesting and dewatering, and algal drying and extraction. Qualitas - large-scale test site for algal harvesting technology. Texas A&M University - algal drying and extraction technology. Pacific Northwest National Laboratory - hydrothermal liquefaction technology. GE Water and Power - membrane technology. National Renewable Energy Laboratory - algal techno-economic analysis. Phase 1 of the project resulted in tremendous productivity and pre-processing improvements in an integrated, large-scale, low-cost cultivation and pre-processing process that moved algal technology closer to economic viability for biofuels than ever before. Phase 2 accomplishments further facilitate development of a commercial algal biofuel industry by adding: several top performing strains and strain development tools including breeding; open-pond cultivation innovations that achieved a 30% improvement in overall productivity, an 83% reduction in cost, and a 95% reduction in energy use relative to conventional technology; further improvements in harvesting that led to the Zobi harvester ® as a universal, economical, low energy, commercially available microalgae harvesting solution; breakthroughs in drying and extraction including a new low energy drying process and several new low energy extraction unit operations that together with the Zobi harvester ® achieve a 90% reduction in cost and 97% reduction in energy use relative to conventional technology. These improvements are sufficient to enable economical production of algae biofuel and protein meal co-product if the process were scaled up to a commercial-scale 5,000-acre algae farm.

09 BIOMASS FUELS↗
DOE OSTI2018

Carbon use efficiency diagnostics in Nannochloropsis salina

We report that carbon dioxide (CO 2 ) can be a significant resource input affecting the cost of algae biomass production on an industrial scale. Improvements in biofuel productivity therefore require characterization of CO 2 use efficiency (CUE). RuBisCO saturation with CO 2 is an important factor influencing biomass productivity. During CO2 fixation by RuBisCO, fractionation of carbon isotopes occurs, with preferential fixation of 12 CO 2 , resulting in assimilation of the lighter isotope in algae. This photosynthetic discrimination (Δ DIC-algae ), approximated by the difference between the δ 13 C of external medium and that of algae, is a function of the proportion of CO 2 fixed relative to supply. Δ DIC-algae has been applied to the study of photosynthesis in algae over the past few decades and we have adopted the tool to characterize improvements in conditions optimized for biofuel productivity, such as controlled photobioreactors. We report the use of Δ DIC-algae as a tool for characterizing CO 2 dynamics and RuBisCO saturation in Nannochloropsis salina CCMP 1776, a benchmark strain in algal biofuels research. We use Δ DIC-algae to describe the conditions under which RuBisCO saturation can be achieved to maximize biomass productivity. Finally, our results suggest that determination of Δ DIC-algae can provide important feedback to support engineering and cultural improvements that can impact carbon use efficiency and biomass productivity.

09 BIOMASS FUELS↗
DOE OSTI2020

Balancing Water Sustainability and Productivity Objectives in Microalgae Cultivation: Siting Open Ponds by Considering Seasonal Water-Stress Impact Using AWARE-US

Microalgae have great potential as an energy crop. Scaling-up algal biofuel production in the United States (US) should be done with careful attention to water stress. This study evaluates the regional and seasonal water-stress impact of potential algae-pond deployments in the US. Three site-selection strategies focusing on biomass yield, water-use efficiency (WUE), and water-stress impact, respectively, are applied and compared to meet a US algae biomass production target of 30 million metric tons/yr ash-free dry weight, which converts to 20.8 billion L renewable diesel, via hydrothermal liquefaction. Ranking algae ponds based on biomass yield leads to freshwater consumption of 2.66 km3/yr, resulting in the highest water-stress impact (39.1 US equivalent km3). Under the WUE scenario, water consumption is reduced by 81%, but biomass yield is reduced by 12%. In contrast, adding a water-stress constraint to the biomass-yield ranking reduces water consumption by 50% and water-stress impact by 97%, with a small yield reduction (1.7%). Results show that pond location has a significant effect on water stress and that water stress is not proportional to water consumption or yield. Furthermore, capturing seasonal water patterns is critical for planning because sites in water-abundant regions can have short-term but significant water-stress impacts.

algae, Biofuel, water scarcity footprint, hydrothe↗