Tag Archives: battery

Building Cars Out of Batteries Isn’t as Crazy as It Sounds

Car1

The high cost and limited range of electric vehicles can make them a tough sell, and their costliest and most limiting component are their batteries.

But batteries also open up new design possibilities because they can be shaped in more ways than gasoline tanks and because they can be made of load-bearing materials. If their chemistries can be made safer, batteries could replace conventional door panels and other body parts, potentially making a vehicle significantly lighter, more spacious and cheaper. This could go some way toward helping electric cars compete with gas-powered ones.

Tesla Motors and Volvo have demonstrated early versions of the general approach by building battery packs that can replace some of the structural material in a conventional car. Dozens of other research groups and companies are taking further steps to make batteries that replace existing body parts, such as body panels and frames.

The ability to use batteries as structural materials is currently limited by the use of flammable electrolytes, but researchers are developing safer chemistries that could be used more widely. The approach also raises several practical questions: can the energy-storing body panels be engineered so that even if they’re dented, the car will still work? And how expensive will bodywork be? However, automakers could turn to the approach under pressure to sell more electric vehicles and hybrids to meet stringent future fuel economy standards.

Batteries are the single most expensive item in electric cars, so making them cheaper would make electric vehicles cheaper too. But even without significant breakthroughs, new battery designs could make a car lighter.

One example is the way Tesla has designed the battery for the Model S. The metal casing that protects the battery also serves to make the car frame more rigid, reducing the overall amount of metal needed.

This month, Volvo demonstrated another approach using lithium-ion batteries, which are made of thin films of material that are rolled or folded up to form a battery cell. Researchers at the Lulea University of Technology in Sweden in collaboration with Volvo sandwiched these films between sheets of carbon-fiber composite. The resulting structure was used to replace plastic body parts and a small conventional battery on a hybrid version of the Volvo S80. (The car is a “stop-start” hybrid that uses a battery to make it possible to turn off the engine whenever the car isn’t moving.)

The U.S. Department of Energy’s Advanced Research Projects Agency for Energy is spending $37 million on projects seeking to use batteries as structural materials. (The program is called RANGE, which stands for Robust, Affordable, Next-Generation Energy Storage Systems). In two ARPA-E projects, researchers are figuring out ways to design battery packs to absorb energy in a crash to replace materials now used to protect passengers. For example, rather than packaging battery cells into a solid block, the cells could be allowed to move past each other in an accident, dissipating energy as they do.

Most of the approaches being explored so far still use conventional battery cells — the parts of the pack that actually store energy. If safer battery cells can be made, then this would provide even more flexibility in how a car can be designed. You wouldn’t need to enclose them in protective cases or regulate their temperature to prevent battery fires.

“When you’re not obsessed with protecting batteries, you can be a lot more creative. You’re not limited to the architecture of conventional cars,” says Ping Liu, who manages and helped conceive of ARPA-E’s RANGE project.

To this end, several researchers are developing new chemistries that don’t use flammable electrodes, so the batteries could be safely used as door panels. They’re considering replacing volatile electrolytes with less-flammable polymers, water-based materials and ceramics. Once they have a safer electrolyte, the researchers will look for ways to use the battery electrodes in a cell to bear loads.

Volvo has an experimental version of this approach that uses carbon fibers in composite materials to store and conduct electricity but also to strengthen the composites. The device was formed in the shape of a trunk lid. But it could only produce enough electricity to light up some LEDs, so it couldn’t replace the battery in an electric car or a hybrid. A newer version being developed at Imperial College in London replaces the epoxy that ordinarily holds together carbon fibers in a composite with a blend of stiff materials and ionic liquids that can conduct charged molecules. This forms a type of supercapacitor that could store enough energy to be used in place of a battery in a stop-start hybrid.

For electric cars and hybrids with larger batteries, supercapacitors don’t store enough energy. So to provide enough driving range, some researchers are developing lithium-ion batteries that use carbon fibers for one electrode, but use conventional lithium-ion materials for the opposite one. Others have developed a nonvolatile polymer electrolyte to replace conventional, flammable ones. The resulting material will make it possible to “do two jobs with one thing,” says Leif Asp, a professor at Lulea University. Several ARPA-E projects are taking this kind of approach.

These new electrolytes and load-bearing battery cells are likely more than a decade away from being useful in cars, however. It will be difficult to ensure that the battery stores large amounts of energy and can also be strong enough as a structural component.

Asp says the first applications could be in portable electronics, where load-bearing batteries could replace conventional plastic cases. But if car components can one day be made out of such materials, then batteries could finally go from a limiting factor to a selling point.

Image: Flickr, Asier Llaguno

This article originally published at MIT Technology Review
here

Read more: http://mashable.com/2013/10/29/cars-made-of-batteries/

Once a Joke, Battery-Powered Airplanes Near Reality

Siemansplane

Last month Siemens and EADS demonstrated a new gas-electric vehicle capable of carrying two people and their luggage 900 kilometers — roughly the distance from New York to Detroit — between refuels and recharges. The prototype was not a car, but a small two-seater airplane.

The hybrid plane is similar to the Chevrolet Volt in that it relies on an electric motor and uses a gas engine as backup. The airplane matches the performance of some private airplanes already on the market, but it has two distinct advantages: It is remarkably quiet and uses about 25% less fuel.

The achievement presages what is likely to be a big shift toward hybrid propulsion in airplanes. Several major corporations envision a future in which airplanes rely at least in part on electric propulsion. Although the technology will be applied to small planes at first, eventually it could help reduce noise and emissions from airliners.

“Within this decade, we will certainly see hybrid electric aircraft entering the market,” says Frank Anton, who heads the hybrid aircraft efforts at Siemens. Four-seat hybrid aircraft are likely within that time frame, he says, but even 19-seaters are possible before the decade is out. Anton predicts that eventually we will see 100-passenger hybrid aircraft that use half as much fuel as today’s airplanes.

Boeing is taking this a step further with a concept for hybrid airplanes the size of 737s — which can seat more than 150 passengers — although it’s unlikely these will come into service before 2030. EADS, the parent company of Airbus, has also developed a conceptual design for passenger airplanes that fly exclusively on electricity, although the range of these aircraft would be limited.

hybrid plane

The new plane is the first to have a hybrid drivetrain. Image courtesy of Siemens

“A few years ago, the idea of flying an airplane on batteries was a joke,” says Marty Bradley, a principle investigator for advanced aircraft concepts at Boeing Research and Technology. While batteries and electric motors are efficient and quiet, batteries tend to be big and heavy, storing far less energy than liquid fuels.

Two things have changed. The amount of energy that batteries can store is steadily improving, and this looks likely to continue as they’re developed for use in portable electronics and electric vehicles, Bradley says. Meanwhile, the technologies needed to integrate batteries and electric motors with conventional engines are getting smaller, lighter and more efficient. Siemens demonstrated an earlier version of its hybrid airplane in 2011, but it was too heavy to be practical. For the new plane, Siemens decreased the weight of the electric motor, power electronics and gears by 100 kilograms to bring its cargo and passenger capacity up to the level of similarly sized small planes.

In airplanes, a hybrid electric design improves efficiency mainly by making it possible to use a relatively small gas-powered engine designed to run at its most efficient at cruising speeds. The battery and electric motor provide the extra power needed for takeoff and ascent. The batteries also make it possible to recover energy during descent much the way hybrid cars capture energy during braking (propellers spin a generator). And, as batteries improve, they will provide more and more of the energy on board.

Electric motors confer other advantages. They can be mounted in unusual places on an airplane, which can be used to improve aerodynamics. They can also be steered: angled upward, for example, during takeoff to get a plane off the ground faster. In flight, the motor could be pointed left or right to steer the plane, eliminating the need for a rudder. These design changes, together with the efficiency of the hybrid propulsion, could help decrease fuel consumption by half, he says.

How fast electric propulsion is adopted depends mostly on the development of the batteries. EADS’s electric airplane plans call for a battery that can store 1,000 watt hours per kilogram, which is about five times more energy than a typical lithium-ion battery. New battery chemistries like lithium-air and lithium-sulfur could provide more capacity, but some big challenges remain. Bradley expects that all-electric aircraft will be limited to 1,600 kilometers until after 2050.

For larger aircraft, electric propulsion might be used to help spin the large turbofans on the front of a jet engine. The first application of electric propulsion for large planes will be for taxiing, allowing planes to save fuel on the ground, he says.

So for the next several years, hybrid technology will be limited to small planes. One near-term benefit of the technology is that small airports (which are often located near residential areas) will be quieter, says Jean Koster, a professor of aerospace engineering sciences at the University of Colorado at Boulder who has founded a company to commercialize a more compact gearbox for combining gas and electric power. Hybrid designs could also put an end to one of the last holdouts of fuel that contains lead: Small airplanes with high compression engines still require lead additives. In fact, the battery boost could make it possible to use the same gas-powered engines used in hybrid cars.

Image courtesy of Siemens

This article originally published at MIT Technology Review
here

Read more: http://mashable.com/2013/07/08/battery-powered-plane/