Energy Storage News
(and Other Related News)

Rogerkb [at] energystoragenews [dot] com

Category 1 Category 2 Date Comment Source





Solar Cells silicon PV 11/16/2017 A company called ENOW is selling silicon solar panels for truck and bus top applications. The purpose of these rooftop PV systems is to keep the battery charged for running auxiliary systems. The claim is that the PV systems reduce idling time thus saving diesel fuel and at the same time reduce wear and tear and on the alternator and the battery thus decreasing maintenance costs and increasing the life time of these systems. ENOW claims to have installed more than 4500 of these systems. This use of solar panels is hardly a world saver since we really eliminate fossil fueled powered transportation completely and not just reduce idling time, but nevertheless this application of PV panels is another sign of the advancing performance and decreasing costs of this technology. enow





Batteries NMC Cathodes 11/13/2017 A German company called Akasol is manufacturing lithium in battery packs for hybrid and electric bus markets. They use batteries with the nickel-manganese-cobalt (NMC) cathode chemistry which is widely used in electric vehicle applications. This is the cathode chemistry used in the batteries produced in Tesla's lithium ion Gigafactory. Akasol uses two versions of this cathode, a standard version and so-called nano-version. Characteristics of battery packs produced using these cathodes (taken from the data sheet on Akasol's website) are listed below:

Standard: Mass=353kg, Volume=250liters, Capacity=35.3kWh, cycle life>3100 at 80% DOD

Nano: Mass=372, Volume=250liters, Capacity=30.6kWh, cycle life>6800 at 80% DOD

One can use these number to calculate the effective energy density of the whole battery pack:

Standard: gravimetric density = 100Wh/kg, volumetric density = 141Wh/liter

Nano: gravimetric density = 82Wh/kg, volumetric density = 122.4Wh/liter

These effective battery pack energy densities are much small than the typically quoted energy density for individual NMC batteries (i.e.>200 Wh/kg). Of course the real battery back mass includes the cooling system, battery management system, and the enclosure

The most impressive performance parameter of these batteries is the cycle life of 3100 for the standard cathode and 6800 for the nano-cathode. What lifetime mileage range can be obtained with these packs depends on the performance of the electric vehicle and the number of packs employed. A NREL study of a fleet of twelve 35 foot long, 35 seat BEV Proterra buses run for an average 33 thousand miles each found thate the average milage was 2.15miles/kwh using 88kWh battery packs. Obviously such buses required frequent charging which was provided by fast charging stations along the bus route. The Proterra buses which took part in this study used lithium titanate cathodes which actually have significantly lower energy density than NMC cathode batteries. Three packs of the Nano-cathode NMC battery would give roughly the same capacity as in the NREL study. If we assume that because of higher energy density we could use four packs with the same weight as the lithium titanate cathodes then the total life time milage range (assuming 2.15miles/kWh) would be:

Life Time Range = 0.8×30.6×4×6800/2.15 = 0.8*30.6*4*6800/2.15 = 308,700 miles.

Therefore, in spite of the low effective energy density, the life time range seems very respectable. Aksol's short term market for these batteries is primarily electric buses, and it is building a new facility with capacity to manufacture 300MWh/year of battery packs
Akasol





batteries Flow Batteries 11/6/2017 A group of scientists in the materials science department of MIT has published an interesting paper on the possibility of using redox flow batteries for long duration energy storage. In true redox flow batteries (as distinguished from hybrid flow batteries) all of the chemical reaction occur in pair liquid electrolytes in the two half cells of the batteries. The electrolytes are stored in tanks and pumped past the electrodes and past an ion exchange membrane which allows ions of a desired type to pass between the two half cells to complete desired chemical reaction. The electrodes are either neutral sources and sinks of electrons or are coated with catalyst that promotes the desired chemical reaction in the liquid electrolytes. However, no solid state reaction such as intercalation or plating occurs on the electrodes. The power rating of the battery is determined by the electrodes, the ion exchange membrane and the electrolyte pumping rate. The energy storage capacity is determine by the size of the electrolyte tanks. This separation of energy capacity from power rating could potentially allow flow batteries to be used for very long duration energy storage is the cost of the electrolytes.

This situation if very different from other battery types where power rating and storage capacity are not independent. For instance the MIT group estimates that the chemical cost of energy storage for the high temperature sodium sulfur batteries manufactured by NGK Insulators is US $1.60/kWh. At this price 32 cycles would be sufficient to lower the chemical cost to US $0.05/kWh. However, their basic battery module delivers 33kW of power for 7.2 hours (i.e. 216kWh of total energy). The basic physics/chemistry of the battery design does not allow any substantial increase of the ratio of energy storage to power. Therefore delivering 720 hours (thirty days) of energy requires 100 batteries to discharge in succession. Since the manufacturing costs are dominated by other factors than the chemical cost of the electrode materials these batteries are not practical for long term energy storage. For example if the total cost of manufacturing the battery exclusive of chemical costs is US $360/kWh then 7200 cycles are required to lower this part of the cost to $0.05/kWh. However, if power and storage time could be decoupled then low cost could be driven by long discharge times rather than by a large number of cycles. 720 hours of discharge delivered ten times would accomplish the same thing as 7200 charge/discharge cycles. Of course 720 hours of discharge (as opposed to 7.2hours) would increase the chemical cost by a factor of 100 so that low chemical cost is the key to making long storage times economical for redox flow batteries.

The MIT group has proposed a low chemical cost flow battery based on sodium and sulfur but with very different reaction than occur in NGK Insulators batteries. They have built a prototype which demonstrates the concept, but which does not have adequate performance for practical storage application. The cycle life is short and the round trip efficiency is low.
cell.com





Solar Cells Concentrated Solar PV 10/31/2017 High concentration solar PV systems have been pursued for some time as a way of utilizing high efficiency multijunction solar cells made from III/V semiconductor compounds (e.g. gallium arsenide). However, the economics of concentrated PV (CPV)has not yet been able to catch up with the increasing economic performance of silicon PV even in geographical locations with low cloud cover in which CPV systems attain their best performance. An Australian company called Raygen is trying to lower the cost of the two axis solar tracking required to obtain high concentration of sunlight by using an array of wirelessly controlled mirrors in a power tower design. The III/V multijunction PV panel sits atop a tower facing an semicircular array of flat mirrors which are rotated in two axes to produce uniform high concentration solar light over the surface of the solar panel. The hope is that this flat array of wireless controlled mirrors can be manufactured and installed at lower cost than the arrays of fresnel lenses which have been more commonly used in CPV installations. Raygen





batteries Battery Pack Management Systems 10/30/2017 A group of researchers at Duke University lead, interestingly enough by a psychiatry professor Stefan M. Goetz, have developed a battery management system which they call a modular multilevel series parallel converter (MMSPC) which allows large battery packs to be dynamically rewired in various series-parallel configurations, generating a wide range of output voltage levels. This control architecture can reduce the battery pack system losses by more than 20% and greatly enhance the operational safety. ieeexplore





Chemical Potential Energy Hydrogen 10/27/2017 Clean Technica recently published a story about a bid for 300MW Saudi Arabian solar project that came in at a quoted price 1.79¢/KWh. A fair amount of skepticism exists about whether this cost estimate can be met in reality, but the fact that these kind of bids exist is a reflection of ongoing cost reductions in the PV industry. Low PV electricity prices, however, are not yet an indication of the arrival of a solar energy millennium. Solar energy flows varies on long time scales (e.g. seasonal) an batteries are an unlikely technology storing energy on such scales. Hydrogen is the most often discussed storage medium for long time scales. Since the cost of electricity is an important component of hydrogen produced from water via electrolysis it is fair to wonder of low solar electricity prices might drive dedicated solar hydrogen production facilities. Such dedicated facilities would have higher capacity factors for the electrolyzers compared to facilities that were only using excess solar electricity. Since transporting hydrogen over long distance is still economically problematic the question how to best utilize the solar hydrogen is an important question. The most obvious easily transportable chemical compound made using hydrogen in ammonia for agricultural uses. Typically the hydrogen required for the production of NH3 is obtained from natural gas via steam reforming. Since 2008 the price of ammonia in the US has varied a lot but has averaged around $600/1000kg. Each 1000kg of ammonia contains 176.5kg of hydrogen. NEL Hydrogen claims hydrogen production rate of it alkaline electrolyzer falls in the range of 3.8 to 4.4kWh/Nm3. If we take the center of this range (4.1kWh/Nm3) and use the fact that 1Nm3 of hydrogen = 0.09kg we can calculate that the electricity consumption required to produce all of the hydrogen in 1000kg of ammonia is 4.1*(176.5/.09)=8040kWh. The price of electricity at which the total electricity cost equals $600 is (60,000¢/8040kWh)=7.5¢/kWh. If solar electricity prices fall significantly below this price then the possibility arises that solar ammonia production could make economic sense. Clean Technica





Chemical Potential Energy
10/22/2017 A Swedish company call Salt-X has developed an energy storage system which utilizes nano-coated salt crystals. The nano-coating porous so that the salt crystals can chemically react with water. During this reaction heat is released. This is the discharge phase of the energy storage process. The resulting crystals of salt + water are a stable form of chemical potential energy storage. In the charging phase heat is applied to the crystals which causes the water to boil off and leave the crystals. The water vapor is collected in a separate vessel where it is stored until a new discharge cycle is required. During discharge cooling occurs in the water vessel as water evaporate and returns to the salt vessel. Thus this energy storage system can produce both heat and cold. Salt-X claims that its nano-coated crystals can support thousands of energy storage cycles. They seem to be mainly targeting building heating and cooling applications with this technology, but apparently the recombination of the salt and water can produce result in fairly high temperatures since Salt-X is also exploring possible energy storage application in concentrated solar power (CSP) which requires superheated steam and thus high temperatures. Salt-X





Chemical Potential Energy Hydrogen 10/17/2017 Liquid organic hydrogen carriers (LOHC) in which hydrogen is chemically combined with organic molecules which can be easily transported in liquid form have been proposed as one possible method of economically transporting hydrogen over long distances. Recently a Spanish research group has developed a ruthenium based catalyst which allows the rapid room temperature evolution of hydrogen from compounds made up of paired alcohols and hydrosilanes. Silanes are not really organic molecules since they are silicon based rather than carbon based, but the resulting alcohol/silane combination is a relatively inert non-toxic liquid which can be transported without special handling precautions such as an inert atmosphere or high pressure. A green car congress article on this compound/catalyst combination implies that its low temperature and high hydrogen evolution rate would allow it to be used directly in automobiles. That is rather than filling up a hydrogen tank in the automobile, one could directly fill up a lower cost tank with the LOHC and then release hydrogen on demand as it is required by the fuel cell. Of course such a scheme would require a two stage refilling process. The spent fuel would have to be extracted from the fuel tank and a fresh batch of fuel loaded with hydrogen would then be pumped into the tank. Ruthenium is platinum group metal with a cost of over 1400 dollars per gm-mol. Ruthenium is much cheaper than platinum which cost about 25400 dollars per gm-mol. If the activity of a catalyst is very high then very small amounts of it can support a large volume of chemical transformations. This is the reason why PEM fuel cells with platinum catalysts are continuing to find useful market niches in spite of the high cost of platinum. Nevertheless if one is hoping to scale up such a fuel production system to support billions of people in high energy use lifestyles then the question of whether or not ruthenium supplies are sufficient to support that lifestyle is relevant. green car congress





Solar Cells Organic Solar Cells 9/25/2017 Organic solar cells are thin film solar energy harvesting devices made from carbon based compounds. They tend to be very cheap to manufacture and have very low embedded energy compared to crystalline silicon PV panels. They can also be deposited on flexible substrates semitransparent substrate which are desirable for building integrated PV applications. However, they have much lower efficiency and typically much lower expected lifetimes than silicon solar cells. Development of this type of solar cell continues because the potential low manufacturing cost is very attractive. A German company called Heliatek is bringing organic solar cells to the BIPB market with a projected lifetime of greater than 25 years and efficiency in the range of 6% to 8% (They have demonstrated 13.2% efficiency in the laboratory). The is efficiency is quite low compared to crystalline silicon cells, but Heliatek believes that the low manufacturing cost along with the ability to laminate their product to a variety of material with an attractive color and appearance will allow them to penetrate the BIPV market. heliatek





Solar Cells III-V semiconductor solar cells 9/23/2017 Multijunction solar cells made from semiconductors which a combination of group III and group V elements (Gallium/Arsenic based semiconductors are the best know) have achieve world record efficiencies (>45% in concentrated sunlight) but have failed to find applications outside of satellite and spacecraft power applications because of the very high fabrication expenses. People have tried to compensate for the high manufacturing cost of III/V semiconductors by using them with concentrating optics in order to greatly reduce the area solar cell used per unit of electricity produced. However, the falling prices of silicon solar cells have so far kept ahead of the cost concentrate photo-voltaic systems. A company call Solvoltaics is pursing another path to applying III/V semiconductors to grid connected power production. They have developed a low cost manufacturing process aerotaxy in which nanowires of a III/V material are nucleated on metal nano-particles in a low temperature gas phase process. The efficiency of the nanowire solar cells produced by this proces is not high by silicon cell standards, but because the ban gap of this material is different that that band gap of silicon the solar cell made with this material utilitze a different portion of the solar spectrum. Solvoltaics strategy is to layer their nanowire cells on top of traditional silicon cells to product a high efficiency tandem cell. How close they are to a practical manufacturing process for such tandem cells is not clear. solvoltaics.com





Batteries Hybrid Flow Batteries 9/17/2017 A research group at the Pacific Northwest Nation Laboratory has developed an aqueous zinc-polyiodide hybrid flow battery with an energy density of 167Wh/l. This energy density is high compared to vanadium flow batteries (25Wh/l) but still less than the low end of lithium ion batteries such as LiFePO<sub>4</sub>. In true flow batteries such as the vanadium battery all of the chemical reaction occur in the liquid electrolytes and the electrodes are merely a source or sink for electrons. The liquid electrolytes by an ion exchange membrane where ions pass between the so called catholyte liquid and the anolyte liquid. The power of such a battery is a function of the membrane properties and the flow rate of the liquid electrolytes. The storage capacity is determined by the size electrolyte reservoirs. The attractive features of flow batteries are the independent determination of power and storage capacity and the lack of solid state interactions in the electrodes which are often associated with failure mechanisms (such a dendrite formation) which limit the cycle life of other battery types. A hybrid flow battery still has liquid electrolytes which are pumped by an ion exchange membrane, but one of the two electrodes has as a solid state chemical process. In the case of the zinc-polyiodide flow battery the solid state process is the plating and deplating of zinc on the anode. A hybrid flow battery no long has the advantages of a true flow battery in that its power and energy storage capacity can no longer be completely decoupled and the zinc anode is potentially subject to solid state failure mechanisms such a dendrite formation. Nevertheless, if costs are low and performance is high then this battery design may find applications. The energy density is high enough that mobile applications are possible in addition to stationary storage applications. nature.com





Thermal Energy Storage Low Temperature Thermal Storage 9/16/2017 Since renewable energy flows have long term time variations (e.g. seasonal) long term energy storage would help to integrate these resource into the economy more effectively. Long term electricity storage is particularly challenging, but long term storage of thermal energy for space and water heating applications may be easier to achieve with reasonable costs. Some Canadian researchers at the University of Ottawa have proposed a system for solar space and water heating which uses an adsorbent placed in an insulated stainless steel column. The adsorbent material generates heat when it is exposed to humid air. In the discharged state the material has adsorbed the maximum amount of water that it is capable of. It can be charged up (that release the adsorbed water) by exposing it to a flow of hot air. When the adsorbent has discharged all of its water and is sealed off from the atmosphere it is in a completely stable state and it can generate heat any time it is exposed to humid air. The propose heating system consist of solar collectors on the roof of a building. The size of the solar collector system is chosen so that it can directly (i.e. with out storage) supply 70% of the heat load over the whole year. Excess heat during the summer is stored in the adsorbent and is used during the winter when the direct solar energy available is much lower. This system provides superior economics to a system which oversize the solar collectors so that they can directly meet the heat requirements on a year round basis. researchgate.net





Chemical Potential Energy Hydrogen 9/14/2017 Platinum free catalysts for the cathode side of PEM fuel cells have matched the activity of platinum based catalysts. However, further improvements in durability/stability are needed before a practical market niche is found for such catalysts. Electrochemical Society





Air Travel Without Fossil Fuels
9/9/2017 Does air travel have a future in a post fossil fuel world? Fuel cell powered planes in which propellers are driven by electric motors are one possibility. A company called Joby Aviation has done an analysis showing that ability of electric motors to deliver high efficiency performance at small sizes allows the possibility of distributed propeller aircraft designs that are much more efficient than designs driven by fossil fuel power internal combustion engines. Apparently the distributed propellors give greater lift thus allowing a smaller wing size and less air resistance. jobyaviation.com





Batteries Flow Batteries 7/3/2017 Scientists have developed an aqueous flow battery based on organic and organometallic reactants with a capacity retention of 99.99% per cycle. The metallic elements used appear to be iron and chromium. Vanadium based flow batteries have very high capacity retention, but concern exists about the scalability of vanadium supply. Iron of course is very abundant in the earth's crust. Chromium has about the same abundance as vanadium but is currently substantially cheaper ($17/gram-mole compared to $112/gram-mole). Of course supply scalability is a complex issue which cannot be simply project from crustal abundance or from current prices. ACS Energy Letters





Batteries Hybrid Flow Batteries 7/3/2017 A startup company called ESS Inc. has developed a hybrid flow battery whose metallic chemistry uses only the element iron. Traditional flow batteries have only liquid phase chemical interactions in the liquid electrolytes in the two half cells. A hybrid flow battery has a solid state chemical interaction in one the half cells. In the ESS battery iron is plated onto the solid cathode in the negative half cell during cell charging. Such solid state chemical processes are regarded as being more problematic than dissolved liquid phase processes with respect to long cycle life. ESS claims, however, that their battery design can withstand 20,000 cycles at 80% DOD. This number compares favorably with the 4500 cycles at 80% DOD achieved by NGK Insulator's sodium sulphur batteries. essinc.com





Batteries Lithium Ion Battery Anodes 4/8/2017 Bio-inspired materials with hierarchical nanopores can be used for lithium ion battery anodes and other applications requiring efficient mass transport. Nature





Batteries Lithium Ion Battery Cathodes 5/14/2017 Low temperature electrodepostion of Litihium ion battery cathodes Science Advances





Batteries Lithium Iron Phosphate Batteries 7/30/2017 The lithium iron phosphate cathode chemistry has been in existence for some time. It has lower energy density than the cobalt based cathodes which are typically used in consumer electronics and in electric vehicles. However, it has longer cycle life and is inherently safer with respect to explosions and fires. A number of battery manufacturers are promoting this technology for grid storage applications in competition with the nickel-manganese-cobalt (NMC) based cathode chemistry of the Tesla Powerwall storage systems. Valence, a manufacturer of lithium iron batteries based in the lithium/iron/phosphate cathode chemistry have successfully entere the market for hybrid and full electric buses. Apparently regular routes with centralized fast charging stations allow these lower energy density batteries to work effectively. Thus the lower lifetime cost and superior safety of this battery type have earned them a market share in this transportation niche. valence.com





Batteries Lithium Sulfur Batteries 7/24/2017 Swedish and Italian researchers have developed a gel polymer electrolyte for lithium sulfur batteries which which greatly reduces the dissolution of polysulfides formed in the cathode. Since polysulfide dissolution is a major factor leading to short cycle life for lithium sulfur batteries this innovation could lead to much longer cycle life for this high energy density battery chemistry. Green Car Congress





Batteries Magnesium Batteries 7/3/2017 Magnesium/Iodine rechargeable battery demonstrated Nature Communications





Batteries Sodium Sulfur Batteries 09/08/09 The Japanese Company NGK Insulators is the sole manufacturer of high temperature sodium sulfur batteries for utility scale electrical energy storage. more NGK Insulators





Chemical Potential Energy Hydrogen 8/29/2017 A number of analysts have denied that hydrogen will have any significant role as an energy carrier in a post fossil fuel future. I do not have a crystal ball with which I can predict the future of energy technology, but I think that a comprehensive dismissal of the future usefulness of hydrogen based energy storage is premature. Hydrogen Energy Storage





Chemical Potential Energy hydrogen 04/23/17 Hydrogen storage based on catalytic amine reforming of methanol is demonstrated. Gravimetric energy density (HHV) is 5.5 times lower than gasoline. JACS





Chemical Potential Energy hydrogen 4/13/2017 Researchers at the National Renewable Energy Laboratory in Golden Colorado have achieved a record efficiency of 16.3% for the direct conversion of sunlight to hydrogen using gallium based multijunction semiconductor devices. Of course gallium based multijunction solars cells have achieved 46% efficiency in the conversion of sunlight to electricity. If you use this current to electrolyze water at 60% efficiency your net sunlight to hydrogen efficiency is 27.6% and you don't have to immerse your delicate light harvesting semiconductors in an acid bath. So it is not clear that this achievement is cause for any great excitement. Nature Energy





Chemical Potential Energy photocatalysis 5/5/2017 A proof of concept experiment has shown that perovskite quantum dots can be in a light harvesting device which photocatalytically reduces CO2 to CO Journal of the American Chemical Society





Compressed Air Energy Storage Adiabatic compressed air energy storage 4/12/2017 A Canadian company called Hydrostor is developing a compressed air energy storage system which which utilized the hydrostatic pressure deep body of water to store air at constant pressure. Their storage system also extracts and store the heat of compression which is recombined with the compressed air to run an expander turbine/generator. They claim 60% roundtrip efficiency for this energy storage system. Hydrostor





Compressed Air Energy Storage Adiabatic compressed air energy storage 3/28/2017 European Research Project on Compressed Air/Thermal Storage energy storage system which would not require fossil fuel burning. RICAS





Compressed Air Energy Storage
05/13/12 If air is mixed with water vapor then the air can be compressed with only a small rise in the temperature of the air/water mixture. Several groups are trying to use this so-called isothermal compression process to store energy. more rheomega.com





Decentralized Energy
4/9/2017 Cheap portable hydrogen peroxide generator could provide off-grid solar powered water purification. Chemistry World





Energy Storage General Topics
8/8/2017 A number of news stories have been posted on the internet recently about energy storage research being carried about by the X skunk works of Alphabet Inc. whose parent company is Google. This energy storage system converts electrical current to sensible heat and cold in molten salt and antifreeze tanks respectively. According to the stories the stored energy will be reconverted to electricity in some sort of air powered turbine. There is a lot of talk about the potential low cost and long cycle life of such a system compared to lithium ion batteries. I have seen no information on the round trip efficiency (=electrical energy out/electrical energy in). This efficiency is likely to be less than 0.5 with significant economic consequences. A brief discussion of the economics of round trip storage efficiency can be found at the link to the right. Economics of Energy Storage Efficiency





Fuel Cells
9/9/2017 The Estonian company Elcogen, a participant in the European NELLHI project, has developed a solid oxide fuel cell with an operating temperature of 650C (compared to 700 to 800&degree;C for state of the art) and an efficiency of more than 70%. The NELLHI project claims that the manufacturing methods, materials, and designs have been optimized for mass production. NELLHI.EU





Fuel Cells
6/30/2017 2% gold nano-clusters on α-molybdenum carbide particles allows fuel cells to use CO as a fuel. Unfortunately the significance of this development could be the increasing use of reformed hydrocarbon fuels as an energy source for fuel cells, not very good news if you are hoping to leave substantial portion of existing fossil hydrocarbon reservoirs in place in the earth's crust. Chemistry World





Gravitational Potential Energy
05/16/14 A company called ARES is planning to build energy storage systems which use electricity to drive a loaded train up an mountain side and then to recover the energy at the train rolls down the mountainside. more Ares





Gravitational Potential Energy
05/16/14 A company called ARES is planning to build energy storage systems which use electricity to drive a loaded train up an mountain side and then to recover the energy at the train rolls down the mountainside. more Ares





Gravitational Potential Energy
08/02/10 Some years ago a company (now defunct) called Mechanical Electric Inc. was proposing to store electrical energy in elevated weights inside high rise buildings. I wrote about why I thought this ideas was economically impractical here.
http:\\energystoragenews.theworldisfinite.com/Energy Storage Round Trip Efficiency.html




micro-cpv
8/1/2017 Concentrated photo voltaic (CPV) systems which use concentrating optics and high efficiency multi-junction solar cells have been attempting to compete with 1 sun solar cells in the large scale utility PV market place without much success. CPV systems harvest substantially more energy per unit area of solar panel but have still been unable to compete with the falling costs of 1 sun solar cells. Now a new development called micro-cpv holds out the promise of putting high CPV efficiency a into flat panel fixed tilt configuration appropriate for roof top installations. The paper referenced by this post describes a system of fixed lenses which produces a concentrated spot of light which moves linearly by a small amount (1cm) as the sun moves in the sky. The high efficiency solar cells which are laminated onto a stiff flat surface can then be move linearly to stay within the concentrated area throughout the day. Whether micro CPV can compete in this market either is not clear. As solar cell costs have dropped installation costs on existing roofs have risen significantly as a fraction total cost and are relatively much higher than in utility scale installations. Higher efficiency (and thus a smaller number of panel installations per roof) will reduce these costs, although whether or not this reduction can offset other excess costs of the system remains to be seen. arpae-summit.com





Solar Cells Silicon PV Heterojunction Cells 8/12/2017 Solar panel design incorporates two technical innovations: heterojunction cells and bifacial cells. read story PV-Tech





Solar Cells Bifacial Solar Cells 7/3/2017 China PV manufacturer Longi Solar has achieved mass production for its bi-facial PERC (passivated emitter rear contact) solar cells. Bi-facial solar cells in which both surfaces of the cell can convert sunlight to electricity can be manufactured with very little additional cost and can increase the effective cell efficiency by 10 to 30% by harvesting defused light on the rear surface of the cell. The extra efficiency achieved depends on the details of the solar panel deployment and of the particular solar environment of each installation. pv-tech.org





Solar Cells
4/11/2017 Researchers at Kaneka Corporation have produce single junction silicon PV cells with a record efficiency of 26.5%. These cells use hetrojunctions in which band gap and of the P-type and N-type regions are different as opposed to homojunction cells in which the bandgaps are the same in both regions. Nature Energy





Solar Cells
4/1/2017 Resonant energy transfer of triplet excitons from pentatene to inorganic semiconductor nanocrystals may lead to more efficient harvesting of solar energy. Nature Materials





Supercapacitors
5/5/2017 This paper shows that structural water included transition metal oxides pseudo capacitors with higher energy/power density ACS Chemistry of Materials





Supercapacitors
3/31/2017 Thin film graphene supercapacitors with fractal electrodes achieve 30 times the energy density of non- fractal designs. Nature





Thermal Energy Storage High Temperature Thermal Storage 2/17/2017 Siemens develops high temperature thermal energy system using rocks as the storage medium and a steam turbine and the electrical power delivery device. Siemens





Thermal Energy Storage High Temperature Thermal Storage 11/01/09 Graphite Energy has developed a high temperature (>2000C) thermal energy storage system using graphite the storage medium. It is not really clear what the market is for this technology, but Graphite Energy seems most hopeful about using it to enhance the efficiency of combined cycle gas turbines. more Graphite Energy





Thermal Energy Storage
10/11/09 Molten nitrate salts can be use for sensible heat storage in concentrating solar power installations. The stored heat is later converted to electricity via a steam turbine. stanford.edu





Tidal energy
3/27/2017 Dual vertical axis turbines place on either side of flow accelerating body ('bluff body') can be used to extract energy from tidal or river flows. Maritime Journal





Water Desalinaton
5/21/2017 Graphene aerogel floating on salt water produces steam under solar radiance and can thus be used to desalinate sea water. Chemistry World





Wind Energy Kite Energy 7/5/2017 Makani is a US base kite energy research group which has been acquired by Google. They started their research using ground based generators which were turned by kit tethers. Now they are pursuing and energy harvesting system in which the generator are flown on the kites and the electrical power is transmitted to the ground through electrical cable that form part of the kite tethers. They are the only kite energy group I know of that is pursing this option. Makani





Wind Energy Kite Energy 7/5/2017 Kite Power Systems is a British research group developing kite based energy harvesting systems. Kite Power Systems





Wind Energy Kite Energy 7/5/2017 Twingtec is another Swiss kite energy company. Their kite looks like and airplane and has both horizontal and vertical propellers. However it still uses a generator sitting on the grown which is turn by the tension in the kite tether. Twingtec





Wind Energy Kite Energy 7/5/2017 Enerkite is a German research consortium active the the field kite energy Enerkite





Wind Energy Kite Energy 7/5/2017 Kitepower is another Dutch research consortium developing energy harvesting high altitude kites. Kitepower





Wind Energy Kite Energy 7/5/2017 SwissKitePower is yet another research consortium developing kite base wind energy harvesting systems. SwissKitePower




D:\Energystoragnews dot com
Wind Energy Kite Energy 7/5/2017 Ampyx Power is Dutch/Australian engineering research group also also working on harvest high altitude winds using tethered kites. Their kites, however, look more like traditional aircraft than like single wing kites. Ampyx Power





Wind Energy Kite Energy 7/5/2017 KITEEnrgy is another Italian research consortium working to develop high altitude wind harvesting based on tethered kites. KITEnrg





Wind Energy Kite Energy 7/4/2017 A number of years ago Hugo Bardi posted a story on a website called The Oil Drum about an Italian research consortium called Kitegen Research which was developing a wind energy system based on high altitude kites whose tethers would be used to mechanically drive a ground based electrical generator. The idea of this energy harvesting system is to harvest the high energy content of high altitude winds with an system which is very dematerialized compared to traditional wind turbines. Most of the energy harvested by traditional wind turbines comes from a relatively small portion of the blades near the tips. A high strong tower and very long blades are required to harvest this energy. The hope is that tethered kites can harvest energy with a much lower ratio of high cost engineered material per unit of energy produced and thus lower production costs. A recent Google search revealed that Kitegen Research is still in existence. A more general search for kite energy revealed that a number of other research groups have joined them in their quest to use kites to harvest high altitude wind energy. Kitegen