In a series-production Audi, a combustion engine currently supplies the music. The motor in an electric-powered e-tron is not an option, as it is too quiet and its high frequencies are not exactly melodious. Audi’s e-tron models will therefore feature a synthetic sound signature. Rudolf Halbmeir teamed up with his colleagues Axel Brombach and Dr. Lars Hinrichsen to create it.

The new sound – which will be fitted to all Audi e-tron EVs – isn’t a single monotone but created on the fly, depending on the speed of the motors, the overall vehicle speed, the current load and more.

The e-sound itself will be played via a loudspeaker attached the vehicle’s undercarriage.

“We designed it to handle as much as 40 watts, but during normal operation it ranges between five and eight watts. That’s loud enough for nearby pedestrians and cyclists to hear the e-tron.”

Audi says while the e-sound for future Audi e-tron electric vehicles will sound similar, each will have a signature note. The sound of the high-performance R8 e-tron, for instance, goes from a purr to a growl when the throttle is tapped.

Researchers at University of California, San Diego are creating a ”nanoforest” that can capture solar energy and use it to generate hydrogen fuel.

Reporting in the journal Nanoscale, the team said nanowires, which are made from abundant natural materials like silicon and zinc oxide, also offer a cheap way to deliver hydrogen fuel on a mass scale.

The trees’ vertical structure and branches are keys to capturing the maximum amount of solar energy. That’s because the vertical structure of trees grabs and adsorbs light while flat surfaces simply reflect it, which is also similar to retinal photoreceptor cells in the human eye. In images of Earth from space, light reflects off of flat surfaces such as the ocean or deserts, while forests appear darker.

“This is a clean way to generate clean fuel,” said Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering.
Wang’s team has mimicked this structure in their “3D branched nanowire array” which uses a process called photoelectrochemical water-splitting to produce hydrogen gas. Water splitting refers to the process of separating water into oxygen and hydrogen in order to extract hydrogen gas to be used as fuel. This process uses clean energy with no green-house gas byproduct. By comparison, the current conventional way of producing hydrogen relies on electricity from fossil fuels.

By harvesting more sun light using the vertical nanotree structure, researchers have developed a way to produce more hydrogen fuel efficiently compared to planar counterparts.

The vertical branch structure also maximizes hydrogen gas output. For example, on the flat wide surface of a pot of boiling water, bubbles must become large to come to the surface. In the nanotree structure, very small gas bubbles of hydrogen can be extracted much faster.

“With this structure, we have enhanced, by at least 400,000 times, the surface area for chemical reactions,” says Ke Sun, an  electrical engineering Ph.D. student who is leading the project.

If hydrogen fuel cells were cheap enough they would be ideal for energy storage for buildings, the grid, and in fuel cell vehicles.

In the long run, the team is aiming for a holy grail of energy production: artificial photosynthesis. It would also capture carbon from the atmosphere, reducing emissions and converting it to hydrocarbon fuel.

The research is published in Nanoscale, and will be presented at the annual Research Expo, in April at the Jacobs School of Engineering.

[source: University of California, San Diego]

The drivetrain of the Mercedes SLS AMG E-CELL has been in development since 2010 as a result of the cooperation between Mercedes-AMG and Mercedes AMG High Performance Powertrains in Brixworth.

A small series-production run of the Mercedes-Benz SLS AMG E-CELL is expected to be launched onto the market in 2013.

The ground-breaking drive system of the technology vehicle boasts some outstanding features: powerful traction is provided by four synchronous electric motors with a combined peak output of 392 kW and a maximum torque of 880 Nm.

The four compact electric motors each achieve a maximum rotational speed of 12,000 rpm and are positioned close to the wheels. As a result, compared with wheel-hub motors, the unsprung masses are substantially reduced. One transmission per axle transmits the power.

Acceleration from zero to 100 km/h in 4 seconds
When it comes to dynamics, the electrically-powered SLS makes a statement: the gullwing model accelerates from zero to 100 km/h in 4 seconds – which almost puts it on the same high level as the SLS AMG with 6.3-liter V8 engine developing 420 kW (571 hp), which can accelerate to 100 km/h in 3.8 seconds.

Further exciting touches are provided courtesy of the agile accelerator response and the straight-line performance: unlike a combustion engine, torque build-up in an electric motor is instantaneous – maximum torque is available virtually from a standstill. The spontaneous torque build-up and confident power delivery – which does not suffer from any interruption of tractive power – are combined with engine running characteristics which are totally free of vibration.

All-wheel drive with torque vectoring enables completely new levels of freedom
Four wheels, four motors – the intelligent and permanent all-wheel drive of the electric SLS guarantees driving dynamics at the highest level, while at the same time providing the best possible active safety. Optimum traction is therefore ensured, whatever the weather conditions.

According to the AMG developers, “torque vectoring” involves the individual control of the electric motors, something which enables completely new levels of freedom to be achieved. Torque vectoring is permanently active and allows for selective distribution of forces for each individual wheel. The intelligent distribution of drive torque greatly benefits driving dynamics, handling, driving safety and ride comfort. Each individual wheel can be electrically driven and electrically braked, depending on the driving conditions, thus helping to:

- optimize the vehicle’s cornering properties,
- reduce the tendency to oversteer/understeer,
- increase the yaw damping of the basic vehicle,
- reduce the steering effort and steering angle required,
- increase traction,
- and minimize ESP intervention.

Torque vectoring enables optimum use of the adhesion potential between the tyres and the road surface in all driving conditions, thereby extending the critical limits of the vehicle’s driving dynamics.

Advanced technology from Formula 1: high-voltage lithium-ion battery
The SLS AMG E-CELL incorporates a liquid-cooled high-voltage lithium-ion battery featuring a modular design with an energy content of 48 kWh. Its development has made use of advanced technology from the world of Formula 1: the battery is the first result of the co-operation between Mercedes-AMG GmbH in Affalterbach and Mercedes AMG High Performance Powertrains (formerly Mercedes-Benz High Performance Engines). Headquartered in Brixworth, England, the company has been working closely with AMG for a number of years. F1 engine experts have benefited from its extensive expertise with the KERS hybrid concept, which made its debut in the 2009 Formula 1 season. At the Hungarian Grand Prix in 2009, Lewis Hamilton achieved the first historic victory for a Formula 1 vehicle featuring KERS hybrid technology in the form of the Mercedes-Benz KER System.

The high-voltage battery consists of 12 modules each comprising 72 lithium-ion polymer cells. This optimized arrangement of a total of 864 cells has benefits not only in terms of best use of the installation space, but also in terms of performance. The maximum electric load potential of the high-voltage battery is 480 kW, which is an absolute best value in the automotive sector. Another technical feature of this considerable performance is the intelligent parallel circuit of the individual battery modules – this also helps to maximize the safety, reliability and service life of the battery. As in Formula 1, the 400-volt battery is charged by means of targeted recuperation during braking whilst the car is being driven.

High-performance control as well as effective cooling of all components
A high-performance electronic control system converts the direct current from the high-voltage battery into three-phase alternating current which is required for the synchronous motors and regulates the energy flow for all operating conditions. Two low-temperature cooling circuits ensure that the four electric motors and the power electronics are maintained at an even operating temperature.

A separate low-temperature circuit is responsible for cooling the high-voltage lithium-ion battery. In low external temperatures, the battery is quickly brought up to operating temperature with the aid of an electric heating element. This helps to preserve the overall service life of the battery. In extremely high external temperatures, the cooling circuit for the battery can be additionally boosted with the aid of the air conditioning system.

“AMG Lightweight Performance” design strategy
The trailblazing body shell structure of the SLS AMG E-CELL is part of the ambitious “AMG Lightweight Performance” design strategy. The battery is located within a carbon-fiber monocoque which forms an integral part of the body shell and acts as the gullwing model’s “spine”.

The fiber composite materials have their roots in the world of Formula 1, among other areas. The advantages of carbon-fiber were exploited by the AMG engineers in the design of the monocoque. These include their high strength, which makes it possible to create extremely rigid structures in terms of torsion and bending, excellent crash performance and low weight. CFRP components are up to 50 percent lighter than comparable steel ones, yet retain the same level of stability. Compared with aluminum, the weight saving is still around 30 percent, while the material is considerably thinner.

The weight advantages achieved through the carbon-fiber battery monocoque are reflected in the agility of the SLS AMG E-CELL and, in conjunction with the highly innovative wheel-selective four-wheel drive system, ensure true driving enjoyment.

The carbon-fiber battery monocoque is, in addition, conceived as a “zero intrusion cell” in order to meet the very highest expectations in terms of crash safety. It protects the battery modules inside the vehicle from deformation or damage in the event of a crash.

The basis for CFRP construction is provided by fine carbon fibers, ten times thinner than a human hair. A length of this innovative fiber reaching from here to the moon would weigh a mere 25 grams. Between 1000 and 24,000 of these fibers are used to form individual strands. Machines then weave and sew them into fiber mats several layers thick, which can be moulded into three-dimensional shapes. When injected with liquid synthetic resin, this hardens to give the desired structure its final shape and stability.

Through their experience with the SLR, the AMG Black Series vehicles and in motorsport, Mercedes-Benz and AMG have accumulated more than 10 years of expertise in working with carbon-fiber materials. AMG currently makes the propshaft for the SLS AMG, for example, in carbon-fiber. On the SLS Roadster, the supporting structure for the draught-stop is made as standard as a carbon sandwich structure. This component, with extremely short cycle times in an industrially oriented manufacturing process, already demonstrates what will be possible in the future.

Optimum weight distribution and low centre of gravity
The purely electric drive system was factored into the equation as early as the concept phase when the gullwing model was being developed. It is ideally packaged for the integration of the high-performance, zero-emission technology: by way of example, the four electric motors and the two transmissions can be positioned as close to the four wheels as possible and very low down in the vehicle. The same applies to the modular high-voltage battery. Advantages of this solution include the vehicle’s low centre of gravity and balanced weight distribution – ideal conditions for optimum handling, which the electrically-powered gullwing model shares with its petrol-driven sister model.

New front axle design with pushrod damper struts
The additional front-wheel drive called for a newly designed front axle: unlike the series production vehicle with AMG V8 engine, which has a double wishbone axle, the SLS AMG E-CELL features an independent multi-link suspension with pushrod damper struts. This is because the vertically-arranged damper struts in the series SLS had to make way for the additional drive shafts. As is usual in a wide variety of racing vehicles, horizontal damper struts are now used, which are operated via separate push rods and transfer levers.

Thanks to this sophisticated front-axle design, which has already been tried and tested in the world of motorsport, the agility and driving dynamics of the SLS AMG E-CELL attain the same high levels as the V8 variant. Another distinguishing feature is the speed-sensitive power steering with rack-and-pinion steering gear: the power assistance is implemented electrohydraulically rather than just hydraulically.

AMG ceramic composite brakes for perfect deceleration
The technology vehicle is slowed with the aid of AMG high-performance ceramic composite brakes, which boast extremely short stopping distances, a precise actuation point and outstanding fade resistance, even in extreme operating conditions. The over-sized discs – measuring 402 x 39 mm at the front and 360 x 32 mm at the rear – are made of carbon fiber-strengthened ceramic, feature an integral design all round and are connected to an aluminum bowl in a radially floating arrangement.

The ceramic brake discs are 40 percent lighter in weight than the conventional, grey cast iron brake discs. The reduction in unsprung masses not only improves handling dynamics and agility, but also ride comfort and tyre grip. The lower rotating masses at the front axle also ensure a more direct steering response – which is particularly noticeable when taking motorway bends at high speed. The ABS and ESP® systems have been adapted to match the special application spectrum of the permanent all-wheel drive.

When commercialized, this 400 Wh/kg battery is expected to slash the price of a 300 mile range electric car by cutting the cost of the battery pack by more than 50 percent.

Envia said its batteries were tested at 400 watt-hours per kilogram at a projected cost of $125 per kilowatt-hour, which is more energy dense than most batteries and less than half of what automakers are paying today, according to the company.

The testing of Envia’s next-generation lithium-ion battery was performed by the Electrochemical Power Systems Department at the Naval Surface Warfare Center (NSWC) in Crane, Ind., under the sponsorship of ARPA-E.

Tests at various cycling rates at NSWC confirmed that Envia’s automotive battery cell demonstrated energy density between 378-418 Wh/kg for rates between C/3 to C/10 for a 45 Amp-hour (C/3) cell. Similar cells have been cycling in Envia’s test labs for over 300 cycles.

Envia is at a prototype phase and foresees it taking at least three years before commercial production.

Envia Systems is a Silicon Valley startup founded in 2007, headquartered in Newark CA, and with a prototyping and manufacturing plant in Jiaxing China.

The company received a $4 million ARPA-E award in the High Energy Density Lithium Batteries program.

General Motors is one of Envia’s high profile investors, and invested $7 million into Envia about a year ago. GM has said that Envia will provide battery technology for future generations of GM’s Volt plug-in hybrid. Other investors in Envia include Japanese giant Asahi Kasei, Pangaea Ventures, and Redpoint Ventures.

The company received a $4 million ARPA-E award in the High Energy Density Lithium Batteries program.

Through improvements to the MEA (Membrane Electrode Assembly) and the separator flow path, which make up the structure of Fuel Cell, Nissan significantly improved the power density of Fuel Cell Stack to 2.5 times greater than its 2005 model and realized a world’s best (Among auto manufacturers) 2.5 kW per liter.

Furthermore, molding the supporting frame of the MEA integrally with the MEA enabled stable, single-row lamination of the Fuel Cell, thereby significantly reducing its overall size by more than half compared to conventional models.

Additionally, compared with the 2005 model, both the usage of platinum and parts variation has been reduced to one quarter, thereby reducing cost of the Next Generation Fuel Cell Stack to one-sixth of the 2005 model.

The latest technology development is part of the company’s continuing efforts towards the realization of a Zero Emission society.

The two companies are building a prototype that could lead to Chevrolet Volt battery packs storing energy, including renewable wind and solar energy, and feeding it back to the grid.

The system could store electricity from the grid during times of low usage to be used during periods of peak demand, saving customers and utilities money. The battery packs could also be used as back-up power sources during outages and brownouts.

Using Volt battery cells, the ABB and GM team is building a prototype system for 25-kilowatt/50-kWh applications, about the same power consumption of five U.S. homes or small retail and industrial facilities.

GM and ABB estimate that, during an outage or brownout, 33 recycled Volt batteries will have enough storage capacity to power up to 50 homes for about four hours. Over time, batteries lose their storage capacity. After seven to 10 years, their storage capacity decreases to about 70% of what they had when new. Furthermore, the batteries are the most expensive component of plug-in electric vehicles. These tired batteries are still suitable for grid storage.

Chevrolet Volt provides an eight-year or 100,000-mile warranty on its battery pack, GM expects these batteries will be able to power the Volt for 10 years so the earliest application likely would come in 2021.

“Our tests so far have shown the viability of the GM-ABB solution in the laboratory and they have provided valuable experience to overcome the technical challenges,” said Pablo Rosenfeld, ABB’s program manager for Distributed Energy Storage Medium Voltage Power Products. “We are making plans now for the next major step – testing a larger prototype on an actual electric distribution system.”

ABB has determined its existing power quality filter (PQF) inverter can be used to charge and discharge the Volt battery pack to take full advantage of the system and enable utilities to reduce the cost of peak load conditions. The system can also reduce utilities’ needs for power control, protection and additional monitoring equipment. The team will soon test the system for back-up power applications.

Last year, General Motors signed a definitive agreement with ABB to identify joint research and development projects that would reuse Chevrolet Volt battery systems, which will have up to 70 percent of life remaining after their automotive use is exhausted.

The projects, supported by the Swedish Energy Agency and the EU, encompass three potential technology combinations. Tests of the various concepts will get under way in the first quarter of 2012.

The company’s technological developments in this area currently encompass three different technology combinations, with three-cylinder petrol engines being installed to complement electric drive to the front wheels. All the variants feature brake energy regeneration. The engines can run on both petrol and ethanol (E85).

Two of the solutions are based on the Volvo C30 Electric and one is based on the Volvo V60 Plug-in Hybrid. In both cases, the standard battery pack has been somewhat reduced in size to make room for the combustion engine and its fuel tank.

Technical concept I: Volvo C30 with series-connected Range Extender
This is based on a C30 Electric with a three-cylinder combustion engine producing 60 horsepower (45 kW) installed under the rear load compartment floor. The car also has a 40 litre fuel tank.
The combustion engine is connected to a 40 kW generator. The power it generates is used primarily to drive the car’s 111 horsepower (82 kW) electric motor, but the driver can also choose to let the generator charge the battery, thus increasing the car’s operating range on electricity.

The Range Extender increases the electric car’s range by up to 1,000 km – on top of the 110 km range provided by the car’s battery pack.

Technical concept II: Volvo C30 with parallel-connected Range Extender
Here the car gets a more powerful three-cylinder combustion engine at the rear and a 40 litre fuel tank. The difference between this and the first solution is the parallel connection, whereby the turbocharged 190 horsepower engine primarily drives the rear wheels via a six-speed automatic transmission. This gives a better fuel efficiency rating when driving with the combustion engine cruising on the highway. Via a 40kW generator the battery can also be charged to give the car increased range on electricity alone.
Here too the electric motor is a 111 hp (82 kW) unit. The two power sources give the car more than 300 hp in total, and acceleration from 0-100 km/h of less than six seconds.

The Range Extender increases the electric car’s range by more than 1,000 km – in addition to the range of up to 75 km provided by the car’s battery pack.

Technical concept III: Volvo V60 with parallel-connected Range Extender
This is a solution whereby the entire drive package is installed under the bonnet at the front. The 111 hp (80 kW) electric motor is supplemented with a three-cylinder petrol turbo engine producing 190 hp (140 kW), a two-stage automatic transmission and a 40 kW generator. Power from the combustion engine drives the front wheels via the gearbox and recharges the battery pack whenever needed.
Up to 50 km/h, the car is always powered solely by electricity. The combustion engine is activated at higher speeds. What is more, it charges the battery pack when its charge drops below a predetermined level.

The battery pack is located under the rear load floor and it gives the driver a range of 50 km on electricity alone. The car also has a 45 litre tank for petrol or E85.

With this technology, the Range Extender increases the car’s total range by more than 1,000 kilometres.

Testing of this new charging system began today at Nissan’s Global Headquarters in Yokohama.

In the new charging system, electricity is generated through 488 solar cells installed on the roof of the Nissan headquarters building. Four batteries from the LEAF had been placed in a box in a cellar-like part of the building, and store the electricity generated from the solar cells.

With seven charging stations (three quick charge, four normal charge) located in the headquarter grounds, the total electricity that can be generated and stored is the equivalent to fully charging approximately 1,800 Nissan LEAFs annually.

This new system will enable electric vehicles, which do not emit any CO2 when driven, to be charged through a completely renewable energy source. This is one solution to create a cycle where CO2 emissions resulting from driving is zero. By using the same lithium-ion batteries in electric vehicles as stationary storage batteries, electricity can also be supplied to EVs regardless of the time of day or weather, enabling efficient use of renewable energy sources.

4R Energy Corporation, a joint venture established by Nissan and Sumitomo Corporation in September 2010, has already started tests on a compact electricity storage system installed with second-life lithium ion batteries previously used in Nissan LEAFs. Based on the outcome of this larger system, 4R Energy plans to enter the market of mid-sized electricity storage systems for commercial and public facilities.

Demonstration test outline

Solar cell: Maximum power output: 40kW
Power conditioner: Rated power output: 40kW (10kW×4)
Storage battery capacity: 96kWh
Grid management unit: Rated power output: 200kW
EV charging equipment: Quick charger: 3 (50kW×3), Regular charger: 4 (3.3kW×14)

In a paper published in the journal Advanced Energy Materials, they said the approach has the potential to boost battery storage capacity many times today’s levels and could even make “refueling” such batteries as quick and easy as pumping gas into a conventional car.

The new battery relies on an innovative architecture called a semi-solid flow cell, in which solid particles are suspended in a carrier liquid and pumped through the system. In this design, the battery’s active components — the positive and negative electrodes, or cathodes and anodes — are composed of particles suspended in a liquid electrolyte. These two different suspensions are pumped through systems separated by a filter, such as a thin porous membrane.

The work was carried out by Mihai Duduta ’10 and graduate student Bryan Ho, under the leadership of professors of materials science W. Craig Carter and Yet-Ming Chiang.

One important characteristic of the new design is that it separates the two functions of the battery — storing energy until it is needed, and discharging that energy when it needs to be used — into separate physical structures. (In conventional batteries, the storage and discharge both take place in the same structure.) Separating these functions means that batteries can be designed more efficiently, Chiang says.

The new design should make it possible to reduce the size and the cost of a complete battery system, including all of its structural support and connectors, to about half the current levels. That dramatic reduction could be the key to making electric vehicles fully competitive with conventional gas- or diesel-powered vehicles, the researchers say.

Another potential advantage is that in vehicle applications, such a system would permit the possibility of simply “refueling” the battery by pumping out the liquid slurry and pumping in a fresh, fully charged replacement, or by swapping out the tanks like tires at a pit stop, while still preserving the option of simply recharging the existing material when time permits.

Flow batteries have existed for some time, but have used liquids with very low energy density (the amount of energy that can be stored in a given volume). Because of this, existing flow batteries take up much more space than fuel cells and require rapid pumping of their fluid, further reducing their efficiency.

The new semi-solid flow batteries pioneered by Chiang and colleagues overcome this limitation, providing a 10-fold improvement in energy density over present liquid flow-batteries, and lower-cost manufacturing than conventional lithium-ion batteries. Because the material has such a high energy density, it does not need to be pumped rapidly to deliver its power.

The key insight by Chiang’s team was that it would be possible to combine the basic structure of aqueous-flow batteries with the proven chemistry of lithium-ion batteries by reducing the batteries’ solid materials to tiny particles that could be carried in a liquid suspension — similar to the way quicksand can flow like a liquid even though it consists mostly of solid particles. “We’re using two proven technologies, and putting them together,” Carter says.

In addition to potential applications in vehicles, the new battery system could be scaled up to very large sizes at low cost. This would make it particularly well-suited for large-scale electricity storage for utilities, potentially making intermittent, unpredictable sources such as wind and solar energy practical for powering the electric grid.

The team set out to “reinvent the rechargeable battery,” Chiang says. But the device they came up with is potentially a whole family of new battery systems, because it’s a design architecture that “is not linked to any particular chemistry.” Chiang and his colleagues are now exploring different chemical combinations that could be used within the semi-solid flow system. “We’ll figure out what can be practically developed today,” Chiang says, “but as better materials come along, we can adapt them to this architecture.”

Chiang, whose earlier insights on lithium-ion battery chemistries led to the 2001 founding of MIT spinoff A123 Systems, says the two technologies are complementary, and address different potential applications. For example, the new semi-solid flow batteries will probably never be suitable for smaller applications such as tools, or where short bursts of very high power are required — areas where A123’s batteries excel.

The new technology is being licensed to a company called 24M Technologies, founded last summer by Chiang and Carter along with entrepreneur Throop Wilder, who is the company’s president. The company has already raised more than $16 million in venture capital and federal research financing.

GM broke ground Tuesday for the previously announced addition to the complex housing its two-mode hybrid and Heavy Duty transmission operations. The electric motor plant results from two investments totaling $269.5 million announced last year.

Electric motor design and production is a core business for GM in the development and manufacture of plug-in electric and hybrid vehicles.

The campus will be powered in part by a 1.23 megawatt rooftop solar array, expected to generate nine percent of its annual energy consumption and save approximately $330,000 during the life of the project.

Constellation Energy will build, own and maintain the solar power system, and GM will purchase all of the electricity generated by the solar panels under a 20-year power purchase agreement. Constellation Energy’s first solar array for GM was a 951-kilowatt system at its Fontana, Calif., Service and Parts Operations warehouse.

GM’s Baltimore Operations has the dual distinction of being powered by renewable energy and generating no landfill waste. It earned zero-landfill status in 2007 by recycling, reusing or converting to energy all wastes from daily operations.