Silicon photovoltaic (“Si-PV”) modules currently dominate the solar energy market. Increased progress into Si-PV efficiency enhancements combined with historically low module costs aim to decrease the overall Levelized Cost of Electricity (“LCOE”) to a point competitive with non-renewable energy sources. Despite recent LCOE reductions, Si-PV technology remains economically inferior to fossil fuels. Additionally, flat-plate Si solar modules generally require geographical locations with high direct normal incidence (“DNI”) sunlight conditions in order to maintain module performance. Both the strict DNI requirement and the high LCOE of Si-PV cells ultimately limit the dissemination of solar power into the global energy market. A solution for the capturing of diffuse sunlight includes the use of optical concentrators.  One class of optical concentrators includes luminescent solar concentrators (“LSCs”).  Luminescent solar concentrators have garnered interest due to their ability to utilize diffuse light and their potential for use in architectural applications such as large area power-generating windows. However, LSCs have not yet reached commercialization for photovoltaic power generation, largely due to their comparatively low power conversion efficiencies (“PCEs”) and lack of scalability.     Researchers at UC Berkeley and other educational institutions have developed luminescent solar concentrators that  can be designed to minimize photon thermalization losses and incomplete light trapping using various novel components and techniques.

Natural gas, composed primarily of methane, has many potential uses as a cleaner and more renewable source of energy than other fossil fuels. However, about 20% of US natural gas reserves contain levels of N2 that are too high for pipeline processing. Using natural gas from renewable sources also encounters this problem. Furthermore, in processing steps to create high-purity methane from its various sources, the removal of N2 remains a significant energetic cost. This separation is typically performed through cryogenic distillation, and improvements in energy efficiency of this separation are necessary to utilize the many available sources of methane. Switching to membrane or adsorbent-based technologies could potentially alleviate this challenge. Size selective molecular sieves and membranes have demonstrated some ability for separating N2 from CH4, but face problems with scalability and selectivity; and current adsorbents need significant improvements in selectivity and capacity for N2 to be commercially viable.  To address this situation, researchers at UC Berkeley have developed a new adsorbent V2Cl2(btdd) with exceptional affinity for nitrogen, such that early experiments already demonstrate a N2/CH4 selectivity of over 10x greater than any reported material. The Berkeley material is a permanently porous vanadium(II)-containing metal-organic framework (MOF). It represents the first example of a MOF with five-coordinate vanadium(II) centers as the primary metal node. The electronic properties of these five-coordinate V(II) centers make this MOF uniquely reactive towards relatively inert and weak electron acceptors, such as nitrogen, creating a stronger M–N2 interaction than any known MOF. Additionally, the high-density of V(II) centers translates to a high gas uptake capacity, qualifying this material as a promising N2/CH4 selective adsorbant. Key performance parameters can be tuned as the building blocks are synthetically modifiable.

Reducing reflection from surfaces is very important for improving the efficiency of solar cells and photodetectors, producing improved optical displays with less glare as well as coatings for high power optical applications. Without anti-reflection (AR), semiconductor surfaces reflect 30-40% of incident light and glass reflects 10-20% even at normal incidence and >70% with large incident angles.  Traditional methods for achieving anti-reflection are through thin film AR coating. The traditional AR coating is designed to be a quarter-wavelength in thickness (typically 50-100 nm) and has refractive index equal to the geometric mean of the two refractive indices of the media between which antireflection is desired. Antireflection is achieved using destructive interference and is necessarily a narrow-band and narrow-angle effect. The anti-reflective performance deteriorates as incidence angle increases and is particularly severe beyond 40-50 degrees. This is a major issue in the presence of diffuse light, which is the case in any realistic environment.  Researchers at the University of California, Berkeley have developed a novel  Nanocone Metasurface that is able to address what AR coating is unable to do at high incident angles. This method significantly augments the properties of a traditional thin film AR coating. A nanocone array is made of silicon nitride sitting on a thin silicon nitride layer. This underlying layer is similar to a traditional thin film AR coating. Underneath the nanocone metasurface is a indium gallium phosphide absorber. The nanocone metasurface serves as an omni-directional anti-reflection coating thereby collecting light from all directions.

There are an estimated 130 million wooden poles that support overhead power lines in the US.  Extreme weather, aging, storms or sabotage can all lead to potential damage of these poles and power lines, which can leave large areas without basic necessities.  Due to this risk, it’s anticipated that power utility companies will deploy sensors and corresponding energy harvesters to better respond to potential damage of this critical electricity grid infrastructure. To address this anticipated mass deployment of sensors and harvesters, researchers at UC Berkeley have developed technology improvements to harvesting of electrical energy from energized conductors carrying alternating currents, such as those on overhead and underground power lines (as well as power-supplying conductors in offices and dwellings).  These enhanced harvesters would improve the economics of deploying sensors across a national power grid.  The Berkeley harvesters can readily provide enough power to supply wireless communication devices, energy storage batteries and capacitors, as well as sensors such as accelerometers, particulate matter measuring devices, and atmospheric sensors.

Surface defects dominate the behavior of minority carriers in semiconductors and optoelectronic devices. Photoluminescence quantum yield (QY), which dictates efficiency of optoelectrics such as LEDs, lasers, and solar cells, is extremely low in materials with a large number of surface defects. Researchers at UC Berkeley and Lawrence Berkeley National Laboratory have developed a bis(trifluoromethane) sulfonamide (TFSI) solution for passivation/repair of surface defects in 2D transition metal dichalcogenide (TMDC). This air-stable solution-based chemical treatment provides unmatched photoluminescence QY enhancement to values near 100% without changing the surface morphology. The treatment eliminates defect-mediated non-radiative recombination, which eliminates the low performance limit of TMDC and enhances its minority carrier lifetime. This novel development can address surface passivation in numerous semiconductors which will lead to highly efficient light emitting diodes, lasers and solar cells based on 2D materials.

More than a quarter of the world's carbon dioxide emissions come from burning fossil fuels to produce heat and electricity. Nuclear energy plants do not emit criteria pollutants or greenhouse gases when they generate electricity. Thermal-neutron reactors are the most common type of nuclear reactor, and light water reactors (LWRs) are the most common type of thermal-neutron reactor, which uses normal water as the primary coolant. Localized corrosion in the primary coolant circuits (PCC) is a big problem in LWRs. The rate of corrosion is often determined by certain electrochemical properties, such as the electrochemical corrosion potential (ECP), solution conductivity, temperature, pH, flow rate, and the kinetics of the reduction of a cathodic depolarizer (e.g. O2) on the surfaces external to the crack. Mechanical loading (stress intensity factor on the crack) and micro-structural/micro-chemical factors (e.g. grain size, precipitates, degree of sensitization) may also contribute to this problem. To address this problem, researchers at the University of California, Berkeley, have developed an operating protocol in which the PCC are protected over wide ranges of parameters as the reactor progresses through a fuel cycle, including: temperature, pH, ECP, solution conductivity, flow rate, and stress intensity factor. Laboratory models using Berkeley approach suggest significant LWR optimization while adding levels of safety and lowering operational costs (e.g., by avoiding primary water stress corrosion cracking in Alloy 600 steam generator tubes, which is a major corrosion phenomena in operating a PWR). In fact, Berkeley’s solutions require minimal modification to the reactor PCC, and in most cases, can be implemented with no modifications at all.

Over the last several decades, polymer membranes have shown promise for purifying various industrial gas mixtures. However, there are a number of potential applications in which highly polarizable gases (e.g., CO2, C3H6, C3H8, butenes, etc.) diminish membrane selectivities through the mechanism of plasticization. Plasticization is the swelling of polymer films in the presence of certain penetrants that results in increased permeation rates of all gases, but an unwanted, and often times, unpredictable loss in membrane efficiency. Current strategies for reducing plasticization effects often result in a reduction in membrane permeability. To address the need for plasticization-resistant membranes that retain good separation performance, researchers at UC Berkeley have developed a novel method for improving polymer membrane stability and performance upon the incorporation of metal-organic frameworks (MOFs). This method can be applied to a broad range of commercially available polymers as well as enable new polymers to be commercialized.

Hydrogen-fueled cell vehicles could gain ground as global researchers develop better processes to produce hydrogen economically from sustainable resources like solar and wind. On an energy-to-weight basis, hydrogen has nearly three times the energy content of gasoline (120 megajoule or MJ, per kilogram or kg, for hydrogen, versus 44 MJ/kg for gasoline). One problem is storing enough hydrogen on-board to achieve a reasonable driving range of 300 to 400 miles. On energy-to-volume basis, hydrogen takes up nearly three times the volume of gasoline (8 MJ/liter for cryogenic liquid hydrogen versus 32 MJ/liter for gasoline). Another problem is related to next-generation solid absorbents like metal hydrides, which typically show weakness in terms of the amount of gas that can be absorbed and delivered. To address these problems, researchers at the University of California, Berkeley, and Lawrence Berkeley National Laboratory, have developed a composite material using nanostructured metal hydrides that is capable of storing three times more hydrogen per volume at room temperature than a comparable cryogenic liquid hydrogen tank. Furthermore, low hydrogen pressures during absorbing and desorbing have been achieved. This represents a significant economic and safety advantage over technologically complex and costly high-pressure (10,000 psi) hydrogen tanks commonly used in mobile hydrogen storage applications today.

Thermochemical cycles combine heat sources with chemical reactions. Energy production from thermochemical cycles are quickly evolving as global researchers develop better processes to generate electricity from sustainable yet intermittent resources like solar. Typical thermochemical processes generate chemical reactants for thermochemical storage. One problem is with efficiency, where these chemical reactants are merely burned together again to recreate heat, which is then converted into mechanical energy that is subsequently converted into electrical energy. Another problem relates to flexibility, in terms of being limited to hydrogen and oxygen as the chemical reactants. To address these problems, researchers at the University of California, Berkeley, are developing a generalized closed-cycle thermoelectrochemical framework with expected chemical conversion efficiencies above 80% and high overall system efficiencies using innovative combined-cycle design.

As the most reducing and lightest metal, lithium is a desirable battery anode material due to its abilities to yield a high cell voltage and a high specific energy capacity. Lithium ion (Li-ion) battery technology is expected to grow to a $30B industry in the next 5 to 10 years. This growth is largely driven by the introduction of electric vehicles which reached one million plug-in electric vehicles globally in 2015. Problems with Li electrodes have been investigated and challenges remain, including dendrite growth, flammability of organic solvents, and decomposition of the anions at the electrode. To address these challenges, researchers at UC Berkeley are developing single-ion, solid polymer electrolytes as replacements for liquid electrolytes. The investigators have demonstrated a solid-state battery system which uses single-ion conduction and leverages three-dimensional connectivity of polymer networks to provide superior mechanical strength and flexibility which affects bulk conductivity.

Nearly all hydrocarbons are generated from petroleum or natural gas processing. Hydrocarbon mixtures are separated into component fractions at scale for the commercial production of fuels and chemical feedstocks. These large-scale systems use a lot of energy and require many sub-systems with expensive adsorbents or membrane materials like zeolites, polymers, metal oxides, and carbon. Since many of these hydrocarbon mixtures have molecules with similar structures, properties, and reactivities, many of the technical challenges and associated high costs remain. Metal-organic frameworks (MOFs) hold promise for efficient and complex separations based on their desirable surface areas, tunable pore geometries, and adjustable surface functionality. To help align MOFs with challenges in hydrocarbon separations, researchers at UC Berkeley have developed thermally robust and tunable MOF materials which are capable of separating mixtures of saturated, unsaturated, and aromatic hydrocarbons. The researchers have demonstrated the purification of a four component gas-phase mixture. 

Conventional power conversion cycles which turn fuel into heat and heat into power are constrained by basic thermodynamic considerations. The most modern technologies have been limited to 60% even with multiple cycles combined (i.e. Brayton and Rankine combined cycle). Recent demonstrations have shown relative efficiency gains of 30% in both spark-ignited and compression-ignited regimes. Researchers at the University of California, Berkeley, are working to outdo these efforts by working on an ultra-high efficiency power cycle framework using argon as the working fluid. Early laboratory results suggest the argon engine could easily achieve 70% or greater thermal efficiency. Under such research the argon replaces nitrogen as the working fluid and is recycled in the closed-loop system.

There are many applications that require the storage of a high density of gas molecules. The driving range of vehicles powered by natural gas or hydrogen, for instance, is determined by the maximum density of gas that can be stored inside a fuel tank and delivered to the engine or fuel cell. In certain situations, it is desirable to lower the pressure or raise the temperature needed to store a given amount of gas through the use of an adsorbent. Developments in next-generation adsorbents, such as metal-organic frameworks and activated carbons, have shown certain weaknesses in terms of the amount of gas that can be delivered when an application has a minimum desorption pressure greater than zero and when a significant amount of heat is released during adsorption or cooling occurs during desorption. To help solve these problems, researchers at the University of California, Berkeley, have developed a next generation of materials using novel porous metal-organic frameworks that demonstrate unprecedented deliverable gas capacities. These engineered adsorbents maximize the amount of gas delivered during each adsorption/desorption cycle. This shows promise in developing next generation gas storage materials for applications with a wide range of operating conditions.

In recent years there has been a greater interest in making more energy efficient automobiles.  A number of plug-in vehicles (PEVs) or hybrid electric vehicles (HEVs) are offered by nearly every automaker today.  Although these vehicles offer a cleaner and more energy efficient alternative to traditional petroleum-fueled vehicles, mainstream consumer acceptance of these technologies is stymied by considerations of their premium price, limited travel range, and extended charging times, all consequences of current battery technologies. To address these problems, UC Berkeley researchers have developed an electro-mechanical flywheel system to be incorporated into PEVs and HEVs which increases efficiency, extends battery life and extends travel range making this battery/flywheel system more cost effective and more appealing to the mainstream consumer.  The system combines the chemical energy storage in a battery with the electro-mechanical energy storage in a flywheel to provide the system with both high power capability and high energy density.   

Supercapacitors are attractive energy storage devices due to their high-power capabilities and robust cycle lifetimes.   “Super” capacitors are named in part because the electrodes are composed of materials with high specific surface area and the distance between the electrode and electrochemical double layer is very small compared to standard capacitors.  A variety of porous silicon nanowires have been developed for use as supercapacitors electrodes by maximizing the specific surface area of active materials.  Although the use of Si is attractive due to its wide-spread adoption by microelectronics industry and due to its abundance, Si nanowires are highly reactive and dissolve rapidly when exposed to mild saline solutions.  Previously, silicon carbide thin films were used to protect the porous silicon nanowires, but the coatings were 10’s of nm thick and while they successfully mitigated Si degradation during electrochemical cycling in aqueous electrolytes, they also resulted in pore blockage and a large decrease in energy storage potential.   Researchers at UC Berkeley have developed methods and materials to improve porous silicon nanowires by overcoming the above limitations.  The resulting nanowires have an ultrathin carbon coating preserving the pore structure while mitigating Si degradation.  The resulting supercapacitor electrodes have the highest capacitance (and hence energy storage) per projected area to date.   

Thermophotovoltaics (TPVs) converts infrared rays from a very hot thermal source into photovoltaic electricity. This process is analogous to using solar cells, but TPVs use thermal emitter and a photovoltaic diode cell to change energy forms. Conventional silicon solar cell is effectively a TPV device in which the sun functions as the emitter, and the cell’s silicon structures absorb in the visible portion of the spectrum. Many solar cell systems neglect the small infrared photon emissions due to known physical and design constraints. Thermophotovoltaic devices are uniquely positioned to overcome that limitation by harvesting the unconverted thermal-infrared emissions. Historically, the efficiency for such devices (with spectral selectivity) reach only 15%. For a world with increasing energy and conservation needs, a thermophotovoltaic module solution would need to perform at higher efficiencies for a variety of high- and low-power demand scenarios. To address these problems, researchers at the University of California, Berkeley, have developed the "Regenerative Thermophotovoltaics" framework which is designed to exploit the small infrared photons typically lost in thermophotovoltaic cells, while architecting the device for optimal variable-demand performance. The Berkeley device framework effectively captures and recycles unused photons in the photovoltaic cell that are generally below ~0.8eV energy. By putting these thermal-infrared photons to work, conversion efficiencies >50% may be produced, which could contend with conventional internal combustion engine (ICE) approaches. 

The selective and efficient conversion of light alkanes into value-added chemicals remains a challenge for those in the petrochemical and chemical industries.  Currently, there is no go-to commercial process for the selective oxidative conversion of C1-C3 hydrocarbons into value-added chemical feedstocks, such as methanol and ethanol. Industrially, methanol is produced in an indirect and energy intensive process beginning with the steam reformation of natural gas into synthesis gas. After fermentation, ethanol is largely produced from the hydration of ethylene/ethene, which relies on the use of concentrated acids and elevates risk for human safety and environment. To overcome these challenges, researchers at UC Berkeley have devised novel materials and methods involving redox-active metals within porous metal-organic frameworks for driving improved catalytic oxidation of small hydrocarbons to their corresponding alcohols and aldehydes. This innovation could be of special importance to the boom of shale gas processing, which consists of largely methane, but also contains large amounts of ethane and other light alkane impurities.

Berkeley researchers have created an electric fan with visual detection camera and movement recognition software to identify the presence and location of occupants. Occupant tracking algorithm localizes air movements to individualize comfort and conserve energy. The fan can be integrated in ceilings, wall partitions or office furniture.

There is increasing commercial interest in small-scale, electricity generator applications that harvest energy from mechanical vibrations or linear motion.    To address this interests, researchers at UC Berkeley have developed a magnetic circuit architecture that has higher flux densities -- on the order of one Telsa -- across large functional air gaps. This circuit generates large induced voltages that can be easily rectified and stored to power wireless devices such as condition monitor sensors.    This innovative circuit can be used to efficiently transduce any linear kinetic energy but is particularly attractive for small-scale applications because the magnetic circuit generates large induced voltages for overall device length scales on the order of millimeters and centimeters. The source of the kinetic energy that is transduced can come from coupling to mechanical motion, mechanical vibration, current carrying conductors, fluid flows or pressure differences.

Researchers at the University of California, Berkeley have designed a reactor cavity, reactor vessel, and core barrel system that has desirable features for use with fluoride salt cooled high temperature reactors (FHRs). The FHRs offer two potential advantages: smaller equipment size, because of the higher volumetric heat capacity of the salts, and the absence of chemical exothermal reactions between the reactor, intermediate loop and power cycle coolants for increased safety. The FHR is a pool type reactor, with a reactor vessel design similar to that commonly used in pool-type sodium fast reactors (SFRs).  General design practice in SFRs is to have a separate guard vessel to maintain the coolant inventory in the primary system if the reactor vessel leaks or ruptures.  This invention uses a different design approach that eliminates the need for a guard vessel. The design also provides useful structures to hold intermediate and emergency cooling heat exchangers and other equipment needed for operation of the reactor.

Currently Li-ion battery recycling returns less than 10% of the original battery value. In addition, much of the non-recycled components are discarded in landfill. Li ion battery technology is expected to grow to a $30B industry in the next 5-10 years. In large part this will be driven by the introduction of electric vehicles. A conservative estimate for the number of electric vehicles by 2015 is one million. To address this challenge, investigators at University of California at Berkeley have developed a method of producing pre-lithiated graphite from recycled Li-ion batteries. This offers an opportunity to introduce novel materials into Li ion battery technology at a very large scale. For example, a typical electric vehicle battery uses a 30kWhr battery, which will need 30kg of anode material. In the case of graphite, this could represent a cost opportunity of ~$500 per vehicle. This invention can provide graphite at a minimum savings of 10% by increasing the performance of the graphite through re-manufacturing. For the first time, this innovation allows for the extraction of the components of a Li-ion battery for complete recycling, and in the case of the anode, re-manufacturing of graphite. This is accomplished by opening cells at a specific state of degradation and under specific conditions. The unique process allows for a specific level of pre-lithiation to be reached and achieving a suitable anode material for specific applications of Li-ion batteries, e.g. high power, high energy, novel anodes, etc. The unique feature of this invention is that the graphite is both re-manufactured (and thus re-used) as an anode, as well as a source of pre-lithiation.

Underground jacketed and unjacketed power distribution and transmission cables are subject to ongoing deterioration. Furthermore, the concentric neutral (CN) wires in these cables can corrode and break. Power utilities have great interests in determining the condition of CNs -- in situ while they are energized in their normal state. The use of non-magnetic flexible chains to support current sensors enables a single sensing tool to inspect CN currents in underground power cables with various diameters. This approach lowers inspection costs by reducing tool inventories and technician time. To refine this cable inspection approach, researchers at UC Berkeley have developed an inexpensive and safe means of tracking the motion of a CN current sensor during the inspection of high-voltage energized power cables. The Berkeley approach uses off-the-shelf wireless optical mouse systems along with specially developed software to simply, quickly, and safely obtain coordinates of the current sensor movement as the sensing device moves along or circumferentially around the cable under inspection. The software enables the operator to keep the position display automatically within the allowable display area of a computer screen, or to adjust the display parameters for optimal monitoring of the sensor.

With over 100 million tons produced annually, oxygen (O2) is among the most widely used commodity chemicals in the world -- and the demand for pure O2 could grow enormously due to its potential use in processes associated with the reduction of carbon dioxide emissions from fossil fuel-burning plants.   The separation of O2 from air is currently done on a large scale using an energy-intensive cyrogenic distillation process. Zeolites are also used for O2 / N2 separation, however this process is inherently inefficient as the materials used adsorb N2 over O2 with poor selectivity.   To address this situation, researchers at UC Berkeley have developed novel redox-active metal-organic frameworks for gas separation. In comparison to conventional materials, the Berkeley material displays incredible separation properties at temperatures that are much more favorable to those currently used in numerous gas separaton and storage applications.   

Operation of axial or radial turbines under wet conditions is generally avoided because of three performance disadvantages: (1) droplets are unlikely to strike the turbine blades in a way that efficiently converts their momentum to rotor torque; (2) the liquid film that forms on the turbine blades alters the aerodynamics of the flow and makes it challenging to optimize the design for performance; and (3) droplet impingement in conventional turbines can cause the rotor blades to erode, and thereby shorten the life of the turbine. To address this problem, UC Berkeley researchers have developed a turbine design that is optimized for wet operation (i.e. operation with internal flow of liquid and vapor fluid phases). As the replacement for the expansion valve in vapor compression refrigeration and air-conditioning systems, this innovation can significantly enhance the energy efficiency of vapor compression systems by extracting additional power output and increasing the heat absorbing capacity of the refrigerant in the evaporator. Another version of the innovation can be used as the work output turbine in a Rankine cycle power generation system designed for wet turbine operation. This wet expansion cycle design has significantly higher heat input heat exchanger effectiveness, and higher energy efficiency than conventional Rankine cycles with superheat. 

There is strong commercial potential in the use of piezoelectric crystals for AC electricity sensors and in energy scavenging from nearby energized conductors. However, the widespread adoption of piezoelectrics in these applications is predicated on low cost of ownership including long lifecycles that don't require maintenance -- such as replacing batteries or failed parts. Therefore, improving the duration of the no-maintenance lifecycle of this technology strengthens its market potential for broad commercial penetration. To address this opportunity, researchers at UC Berkeley have developed a means of dynamically adjusting the operating properties of piezoelectric crystals used in AC electricity sensing and energy scavenging applications. This dynamic adjustment reduces the fatigue of piezoelectric crystals thereby promoting a longer lifecyle. In addition, the dynamic adjustments are implemented via circuit means -- instead of mechanical means that require relatively substantial power.