Lab Partnering Service Discovery
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NREL has developed the following laboratory analytical procedures (LAPs) for standard biomass analysis. The American Society for Testing and Materials (ASTM) and the Technical Association of the Pulp and Paper Industry (TAPPI) may have adopted similar procedures. ASTM and TAPPI versions may be ordered from those organizations.
Near-infrared (NIR) calibration models are created by applying multivariate calibration methods to the combination of wet chemistry data and NIR spectra of a given set of biomass samples. Wet chemical compositional data and NIR spectra exist for the following types of biomass samples: corn stover, switchgrass, mixed hardwoods, mixed softwoods, sorghum, and miscanthus. These samples may be feedstock samples, washed and dried solids from one or more pretreatment processes, liquors derived from one or more pretreatment processes, or whole pretreated slurries.
Recent investigations by a number of groups have shown that a beta zeolite catalyst (and other solid Brønsted acids) will convert methanol and/or dimethyl ether (DME) to iso-alkanes such as triptane (2,2,3-trimethylbutane), with uniquely high selectivity to C4 and C7 (termed the DME to high octane gasoline process or DTHOG). In comparison, the Exxon-Mobil methanol to gasoline (MTG) process produces a broader mixture of hydrocarbons, which is heavy in benzene, toluene, and xylene (BTX). DTHOG is milder than MTG (350-450 °F vs. 650-950 °F and 130 psia vs. 315 psia), thus offering the benefit of reduced capital and operating costs for the reactor. However, similar to MTG, this new low-temperature, selective production of alkanes is still a hydrogen-deficient process. That is, to produce alkanes, a quantitative production of aromatics is required to maintain stoichiometry—a result of oxygen from methanol or DME being rejected as water.
Scientists at the National Renewable Energy Laboratory (NREL) have developed a catalyst formulation and structure that is capable of incorporating hydrogen from gaseous co-fed H2 into methylation and alkylation products without altering aliphatic hydrocarbon selectivity or lowering reaction rates. Volumetric and gravimetric activities are increased and the rate of formation of heavy aromatic residues is decreased. The catalysts are comprised of a beta zeolite modified with Cu, Ga, other non-noble metals, and combinations thereof. The metals provide sites for H2 dissociation, hydrogen addition, and hydrogen abstraction, all of which modulate critical reaction steps—providing H for alkane formation and H removal for alkene formation, bringing products back into the carbon chain growth pathway and minimizing side-reactions that produce unwanted byproducts. The metals work with the Brønsted acids of the zeolite, which act as the catalyst for alkene methylation and carbon chain growth. Physical mixtures of the metal catalyst and zeolite do not yield the same benefits. Metal loadings are low (< 5 wt%) and include metals in metallic clusters, oxide clusters, and cationic forms.
Low-cost energy storage solutions have the promise to make carbon-free renewable solar- and wind-generated energy readily available on the electric grid and to put more electric vehicles (EVs) on the road. However, today’s 10-year lifespan of batteries for these applications cannot compete with the 20- to 30-year lifetime of fossil-fueled power-peaking plants or the 15- to 20-year lifetime of conventional petroleum-powered vehicles. Additionally, the problem of Lithium (Li) loss capacity fade plagues today’s Li-ion battery technologies, shortening their lifespan and restricting their performance.
The cost of Li-ion energy storage systems, presently around $325/kWh, is expected to fall by 45% in the next five years, outpacing most competing storage technologies presently under development. But even if costs are brought below $200/kWh, the limited lifetime of Li-ion battery devices will still impede widespread market acceptance. However, with the implementation of grid-based energy storage demonstration projects and numerous EVs on the road, hope for low-cost energy storage solutions has been renewed and technical and economic analyses are increasingly looking beyond upfront expenses in order to optimize energy storage total life-cycle costs.
Engineers at the National Renewable Energy Laboratory (NREL) have invented a passively triggered excess Li reservoir for energy storage cells to overcome the Li-loss capacity fade. This technology may greatly improve the life cycle and utility of Li-based energy storage systems for both utility and vehicle applications, extending lifetime by more than 50% while adding less than 2% to today’s cell cost.
The excess Li is uniquely released from the reservoir to maintain the cell’s capacity with no need for external circuitry or sensors to control the release. Additionally, both the volume and the mass of the internal Li reservoir are minimized within this novel invention in order to keep costs low. This invention specifies multiple locations for the Li reservoir within commercial Li-ion cells depending on the cell’s packaging and methods to engineer a controlled release rate. In addition to improving capacity retention over lifetime, the invention can also be used to greatly improve the beginning of life capacity of cells employing electrodes such as silicon that suffer from large irreversible capacity loss during their first several cycles.
Current oil and salt based heat transfer fluids have significant limitations such as usable temperature, high cost, and limited thermal conversion efficiency. To achieve the Department of Energy SunShot goal of high efficiency, low cost renewable power generation, a highly efficient and economical way to absorb solar heat and to store the thermal energy is important for broad deployment of concentrating solar power (CSP) plants as baseload power.
Engineers at the National Renewable Energy Laboratory (NREL) have developed a high-temperature “direct” supercritical CO2 (s-CO2) receiver for CSP applications. The direct s-CO2 receiver can be coupled with an s-CO2-Brayton power cycle to meet the DOE SunShot cost and performance goals. The near-blackbody (NBB) design employs a working mechanism resembling a blackbody furnace, and minimizes thermal losses from convection and radiation through reducing direct exposure of heated surfaces to the cool ambient surroundings. An ideal blackbody furnace design uses a well-known radiative mechanism and captures nearly all incoming radiation. The infrared (IR) re-radiation losses also behave as NBB emission, therefore a significant design emphasis is on minimizing IR emission. The NBB design maximizes solar energy collection efficiency while reducing IR re-radiation and convection losses for high performance.
This receiver design performs at greater than 650°C operating temperature with less than 10% thermal loss (defined as the ratio of energy delivered to the heat transfer fluid divided by the total energy that enters the receiver aperture), while minimizing the thermal stress (and hence material requirements) of the receiver. Such a design enables use in a modular, small tower s-CO2 power system, where the s-CO2 power block may be directly integrated with the receiver on top of the tower, resulting in less piping requirements and parasitic consumptions.
The global photovoltaic (PV) industry has seen approximately 30% growth each year for the past 15 years, leading to a $10 billion industry. The PV industry is looking to lower the high costs and increase the efficiency of solar power. Scientists at NREL have designed a new process, Black Silicon Etching, that has a confirmed conversion efficiency of 16.8% in a cell without conventional antireflection coatings. This surpasses the previous black silicon record by 2.9%. Additionally, this new technology could lower the Levelized Cost Of Energy (LCOE), or the lifetime cost per unit of energy, by 2.5%.
The winner of a 2010 R&D 100 Award, Black Silicon Etching is an innovative technology that both increases the efficiency of solar cells and decreases the capital costs of producing them. Black Silicon Etching is a one-step process using gold nanoparticle catalysis to etch nanopores into the surface of a silicon wafer, producing a density-graded black surface. The near-complete lack of reflection from the surface of the material means it can absorb more sunlight, and more electricity can be produced. Current technologies first texturize the silicon wafer and then coat the cells with an antireflective layer, which takes 8 to 30 minutes; this two-step process produces cells that reflect 3-7% of the light. NREL’s Black Silicon Etch process requires less than three minutes to complete at room temperature, and creates PV cells that absorb more than 98% of the incident light. Additionally, the cells created will have improved performance during morning, evening, and diffuse light conditions, since the black material can absorb light at incident angles which conventional cells reflect. Black Silicon Etching has been proven to be 16.8% efficient for single-crystalline silicon cells and 14.9% efficient for multi-crystalline cells, eclipsing the best previous density-graded antireflection solar cells which are 13.9% efficient.
Solar cell manufacturing is an expensive, capital-intensive process. Black Silicon Etching is a scalable technology that reduces the capital costs of PV manufacturing. This new process reduces the LCOE by 2.5% which includes $6-15 million capital savings on standard 100MW PV lines. Additionally, this novel process reduces the use of hazardous gases, can be performed with any simple wet-chemistry equipment, consumes less power and generates fewer greenhouse gases, and is easily inserted into 85% of the market’s current manufacturing processes. Black Silicon Etching could greatly improve current PV technologies by increasing the conversion efficiency and decreasing the costs of solar power while integrating smoothly into legacy manufacturing systems.
Ethanol is the clean, renewable, domestic form of gasoline the U.S. needs to decrease its dependence on foreign oil and mitigate pollution from vehicles. However, the current high cost of ethanol production is preventing this renewable fuel from becoming widespread.
NREL has addressed this cost issue in the fermentation step of ethanol production by developing genetically engineered bacteria known as Zymomonas mobilis 8b. Traditional yeasts have the ability to ferment six-carbon sugars, but are unable to ferment five-carbon sugars. This makes for a low yield of ethanol, or if fermented by two separate organisms in two separate fermentation tanks, a high capital cost for ethanol. In response, NREL scientists have taken the bacterium Zymomonas mobilis, which naturally only ferments six-carbon sugars, and genetically engineered it to express foreign genes encoding enzymes needed to ferment five-carbon sugars.
Zymomonas mobilis is known for its ability to rapidly and efficiently convert cellulosic glucose (six-carbon) substrates into ethanol at a low pH in an anaerobic culture, and in a medium which contains the inhibitory compounds typically associated with lignocellulosic hydrolysis. However, six-carbon sugars only make up 30-40% of a typical biomass feedstock and Z. mobilis cannot ferment the remaining five-carbon sugars, such as the xylose from hemicellulose and arabinose from switchgrass and corn fiber. Thus, achieving a high rate of conversion efficiency in the fermentation of five-carbon sugars is vital to the commercial production of fuels and chemicals from renewable substrates.
In response to this challenge, researchers at NREL have utilized a transposon and a plasmid shuttle vector for stable insertion of four exogenous genes from the yeast Saccharomyces cervisiae into the bacterial genome of Zymomonas mobilis. The transposon is useful for stable insertion of foreign genes into a bacterial genome and comprises of at least one operon having structural genes encoding enzymes from the group xylAsylB, araBAD, and tal/tkt, and at least one promoter for expression of the structural genes in the bacterium, a pair of inverted insertion sequences, the operons contained inside the insertion sequences, and a transposase gene located outside of the insertion sequences. The plasmid shuttle vector is useful for the transformation of foreign genes into a bacterial genome.
Previous variants of Z. mobilis are capable of fermenting glucose, xylose, and arabinose at very low conversion efficiency. Additionally, these strains frequently become unstable when grown in the absence of selection pressure or when they have to compete with other organisms such as those in the simultaneous-saccharification-fermentation processes. Z. mobilis 8b exhibits substantially improved stability and can retain native activity for producing pentose and hexose-fermenting enzymes for 80-160 generations, up to 4x more stable than other strains of Zymomonas.
The U.S. Department of Energy (DOE) estimates that a $1 per watt installed photovoltaic (PV) solar energy system - equivalent to 5-6¢/kilowatt hour (kWh) — would make non subsidized solar competitive with the wholesale rate of electricity, nearly everywhere in the United States. In order to reach this goal, manufacturers in the highly competitive solar manufacturing industry have placed a greater focus on two important aspects of their processes - throughput and efficiency. While all sectors of the industry must focus on process improvements, traditional crystalline silicon based manufacturers stand to benefit the most through process improvements because almost one half of the installed cost of a silicon cell solar module is driven by the cost of the silicon wafer. Silicon wafers break during manufacturing due to a combination of large stress in handling and thermal processing, and the fragile nature of the silicon substrate. Wafers that break during the manufacturing process decrease the effective yield and increase the manufactured cost per watt. Therefore, there is a significant cost savings in isolating wafers that would break during manufacturing. Current wafer screening techniques use either highly unreliable infrared imaging or extremely energy intensive method based on optically induced thermal stress. Both these approaches require a great deal of time to accurately test each individual wafer for potential defects. There exists a need in the industry for a wafer screening process with low power requirements that can offer the throughput needed by the photovoltaic industry (1200-2000 wafers/hr). Using the concepts of an optical cavity furnace, scientists at the National Renewable Energy Lab have created a low-power system with the capacity to operate at throughput levels required by high speed solar cell manufacturers.
Wafer screening by optically-induced thermal stress is typically accomplished through a process that contains several water-cooled lamps with parabolic reflectors. As the wafer is transported underneath the reflectors via conveyor belt, all light sources are directed into one small area to optically induce the maximum thermal stress the wafer would be subject to during manufacturing. If the wafer survives this test, it is likely to survive the cell fabrication process without breakage. While this process allows solar manufacturers to screen potentially bad wafers, the water-cooled lamps and reflectors require a tremendous amount of energy. Furthermore, the technique does not allow for high throughput processing.The proposed new method of screening wafers takes advantage of the concepts of an optical cavity furnace to build a high throughput wafer screening machine with low power requirements. In much the same manner as the traditional method, the wafer in the improved system is transported through the process via conveyor belt. However, in the improved system, an optical cavity is formed by placing optical sources within the reflecting walls of the furnace. This design ensures that -energy coming from the light sources is transferred to the wafer only, resulting in substantial energy savings over the traditional method. After the wafer exits the cavity furnace, it is then subjected to either a a jet of cold air or an ambient of a water-cooled camber to release the thermal energy. This dynamic temperature profile of the wafer produces a predetermined time-dependent stress in the wafer, which corresponds to the highest stress the wafer can experience during solar cell processing. This process has the capability to reach the required throughput levels of approximately 2,000 wafers/hr in a modular system that sits quietly on top of any existing line and uses far less energy than the traditional system.
This invention can produce copious quantities of carbon nanotubes at rates near grams per hour. It is an RF-induction heated side-pumped synthesis chamber for the production of carbon nanotubes.
Such an apparatus concurrently provides a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization.
Manufacturers of semiconductor devices in the microelectronic and photovoltaic industries have long been plagued by the costs of wafer fabrication. Currently, process steps such as phosphorous diffusion, aluminum alloying, coating deposition, hydrogen passivation and contact formation must be completed at extremely high temperatures. In addition to the substantial cost of heating the system, high process temperatures can introduce impurities and reduce the overall quality of a device. Currently, wafers are either processed in conventional electric or infrared furnaces. Conventional electric furnaces require the exposure of the device to high temperatures for extended periods of time and, as a result, are expensive, slow, and can result in impurity redistribution and distortion of the wafer. In contrast, infrared furnaces use a powerful optical source to quickly raise the temperature of the semiconductor device, offering a slight improvement in required energy and process time over conventional systems. Unfortunately, the non-uniform light source in the infrared furnace creates temperature variations over the wafer which can result in defects, dislocations, and wafer breakage.
Recently, improved optical furnaces have been created that can provide a uniform light source, but lack the speed and throughput required to be utilized on a high throughput production line. Due to the inherent limitations of the current state of the art, there exists a need for an energy efficient method to process wafers at a high throughput level. Using the concepts of an optical cavity furnace, scientists at the National Renewable Energy Lab have created a low cost method to process high quality semiconductor devices at speeds required by both the semiconductor and photovoltaic industries.
The optical furnace uses the principles of photo-absorption and other photonic effects to provide manufactures of semiconductor devices with a low cost, high throughput alternative to current process methods. The optical furnace sits on top of a manufacturing line and is formed by placing optical sources within the reflecting walls of the furnace. This design ensures that all energy coming from the light sources is transferred to the wafer only, resulting in substantial energy savings over the traditional method. Once inside the furnace, the wafer is processed in a manner dictated by the control of the following process parameters. First, the power and location of the optical source can be tailored to provide the desired optical flux distribution. Second, the transport rate controller can alter the speed with which the wafers are transported through the furnace. Third, a process substance controller is used to control the withdrawal or addition of substances such as processes gasses from the optical furnace.
These process parameters can be adjusted to a device manufacturer’s process line to complete a wide variety of process steps in an energy efficient manner that minimizes impacts to the surrounding layers of the device. For example, manufacturers looking to remove impurities from a semiconductor substrate or solar cell can use the furnace to first hydrogenate the backside of the substrate, and then illuminate it with electromagnetic radiation at intensity and for a time period sufficient to cause the impurities to diffuse to the back side. There, the impurities alloy with a metal already present in the device and form a contact that captures the impurities. This process is ideally suited for a solar manufacturer who seeks to simultaneously passivate defects within the device and form a contact, as the high intensity electromagnetic radiation is sufficient to sinter/alloy the metal contacts. Additionally, a solar manufacturer can use the furnace to produce a thin SiO2 film on a silicon substrate to minimize surface recombination and improve cell efficiency. During dry oxidation, the silicon wafer is about 1000°C, the furnace walls at about 500°C, and the quartz chamber is at about 200°C. This means that the furnace is almost immune to the contamination from hot walls of the quartz chamber that conventional furnaces are plagued with.
The optical furnace also lends itself as a very efficient concentrator of light. This feature of the furnace has been used to develop an online wafer screening system that separates those wafers that have propensity to break during solar cell processing. The light generated by the concentrating furnace is used to optically induce the maximum thermal stress the wafer would be subject to during manufacturing. If the wafer survives this test, it is likely to survive the cell fabrication process without breakage. The optical furnace has the capability to reach the required throughput levels of approximately 2,000 wafers/hr in a modular system that sits quietly on top of any existing line and uses far less energy than the traditional system.
Solar power generating capacity has grown from 83 MW in 2003 to over 7,200 MW in 2012, in the U.S. alone. As the solar industry grows, there is a significant need for quality control and testing methodologies. Both testing and quality control of photovoltaics (PV) and power electronics are essential to innovation and efficient production. Accurately testing new materials and manufacturing techniques in a quick and simple way can lead to unique insights and reduced manufacturing costs and throughput times.
Minority carrier lifetime is an important material parameter in PV. Minority carrier lifetime is highly sensitive to impurities and intrinsic defects, both which affect cell efficiency. Hence, minority carrier lifetime measurement is an ideal parameter for characterization of material quality and process control. By accurately and quickly measuring minority carrier lifetimes, materials can be adjusted and manufacturing defects can be caught quickly and cost effectively.
NREL scientists have developed a unique apparatus and process to determine BULK-minority carrier lifetime. This development measures the minority carrier lifetime in a semiconductor wafer or thin film from the frequency dependence of the capacitance of the junction formed by the semiconductor and a liquid conductor.
This is done by contacting the surface of a semiconductor material at a first location with the first conductive liquid probe to form a Schottky junction and contacting the surface of the semiconductor material at a second location with a second contact. A forward bias is applied to the Schottky junction causing minority carrier injection in the semiconductor material. The minority carrier lifetime of the semiconductor material is determined from the inflection frequency of the total capacitance between the contacts as a function of frequency.
This in turn results in BULK lifetime measurement and is less sensitive to surface recombination velocity and treatment. The measurement can be taken without a source of light and takes only seconds to accomplish the measurement. This method could be used for any sort of semiconductor manufacturing processes.
This algorithm calculates the solar and lunar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of +/- 0.0003 degrees for the Sun and +/- 0.003 degrees for the Moon, based on the date, time, and location on Earth.
The algorithm can be used for solar eclipse monitoring and estimating the reduction in solar irradiance for many applications, such as smart grid, solar energy, etc.
The most common way of describing the quality of an existing or potential wind or solar power generation site is the total amount of energy expected to be generated based on typical weather patterns. This total amount of energy is characterized by the capacity factor (the ratio between the expected generated amounts to the maximum possible amount for hypothetical conditions of constantly blowing wind or sunshine for a 24 hour period). The capacity factor gives a correct estimate for the useful amount of generated energy when only a small fraction of power comes from wind or solar resources and there are no significant curtailments.
The proposed method provides a consistent measure for renewable power quality. The difference between the overall amount of energy (capacity factor based estimates) and the useful energy (this method) can be as high as a factor of two and will influence the choice of wind or solar generators. The new method of characterizing renewable energy resources will be useful to different users.
NREL scientists have developed software that accomplishes two key items:
- Characterizes detailed weather conditions for a given area over a significant span of time. This develops a broad set of potential wind and solar generation sites in the area with their corresponding individual generation profiles. The weather condition characterization includes historic measurements and detailed weather modeling
- Determines the planned set of generation sites that will be built, maximizing the amount of un-curtailed (useful) energy from each site, and thus minimizing the costs associated with building the generation sites
Individual sites are presented based on the criteria for best load support, the sites number in the tens of thousands across the western U.S., excluding Alaska. The results show that about 80% of the load can be matched with wind and solar, while curtailing less than 10% of the generated energy.
This software could be useful for energy developers, infrastructure development, utility risk management, and others that are interested in site development that includes transmission issues as well as generation potential.