Tag Archives: cars

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

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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/

Double-Decker Solar Cells Capture More Sunlight

Swiss engineers have demonstrated tandem solar cells layered so they can catch more of the solar spectrum, providing a route to cheaper and more efficient solar power. The cells are not yet ready for commercial applications, but could mark a major step forwards for renewable energy.

Traditional solar cells present engineers with a fundamental problem. The colors in sunlight are photons of different energies,but individual cells can only extract the same amount of energy from each photon, leaving designers with a choice. One path involves collecting high-energy photons and missing out on the majority of the Sun’s photons whose energy is too low. The alternative is to harvest a larger portion of the spectrum, but only get a small amount of energy from each photon, so that much of the potential of higher energy photons is wasted.

This problem can be resolved by placing different types of cells on top of each other, with the top layer catching high-energy photons while letting those of lower energy through to be captured by another cell below. Multi-junction cells that stack four layers upon each other have achieved 46 percent efficiency,but at prices notviable for most circumstances. An alternative path is to split sunlight with a prism so that each cell gets the light for which it is most suited.

Professor Ayodhya Tiwariis co-leader of a team at Empa-Swiss Federal Laboratories who have announcedin Nature Communicationsaproof of conceptfor a way to make the top cell cheaply enough for widespread use, while still letting most of the unused light through.

Tiwari’s version uses the new wondermaterialperovskitefor the top cell, with copper indium gallium diselenide below. Perovskite is a naturally occurring mineral that can also be manufactured for energy-collecting purposes. Although still not as efficient as the best solar cells, progress in perovskite materialhas happened far more rapidlythan any other solar material ever tried.

While most solar cells, perovskites included,require high-temperature manufacturing, greatly adding to the cost, Tiwari created the top layer at 50C (122F), opening up the possibility of very cheap mass production.

The test cells used perovskite crystals to collect 14.2 percent of the energy in sunlight, while letting 72 percent through. The cell below captured another 6.3 percent. The total efficiency of 20.5 percent is similar to the best commercial cells and nothing exceptional by laboratory standards. However, Tiwari claimed in a statementthat 30 percent efficiency is in sight for the cells made this way.”What we have achieved now is just the beginning,” he said.”We will have to overcome many obstacles before reaching this ambitious goal.”

Higher efficiency, even at the same price per watt, would makesolar energy more attractivewhere space is limited (such as the roofsof electric cars)and reduces the costs of installation and associated infrastructure.

Perovskite cells currently lack the durabilityof silicon crystals though, particularly when exposed to water, and this remains the biggest obstacle to their widespread use.

Read more: http://www.iflscience.com/physics/double-decker-solar-cells-capture-more-sunlight-0

Toyota releases fuel cell patents for royalty-free use to all

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Toyota senior vice president of automotive operations Bob Carter on stage at CES 2015.
Image: Mashable, Christina Ascani

LAS VEGAS — Toyota just rocked the auto industry by announcing that it is opening to the public 5,680 of its patents related to fuel cell technology for royalty-free use.

Bob Carter, the company’s senior vice-president of automotive operations, delivered the news on Monday at CES, following an elaborate presentation that touted the strengths of its fuel cell vehicle, the Toyota Mirai.

There was a collective gasp from the audience after Carter’s announcement, likely because the decision could help jumpstart this area of the automotive industry, which is exactly what Toyota is counting on.

By eliminating traditional corporate boundaries, we can speed the development of new technologies, and move into the future of mobility more quickly, effectively and economically,” Carter said.

Just before Carter made his announcement, famed theoretical physicist Michio Kaku delivered a speech about the future of technology in general, as well as the future of cars as represented by the Mirai. (For fans of Kaku, it was both a treat to see him, but also a slight letdown that one of the leading minds behind superstring theory is promoting cars — no matter how futuristic those cars may be.) All in all, Toyota’s point was clear: It is focused on future tech, and the Mirai (Japanese for “future”) is a big part of that focus.

Toyota Fuel Cell event at CES 2015

Dr. Michio Kaku on stage at CES 2015.

Image: Mashable, Christina Ascani

For many, Toyota’s patent announcement will bring to mind Tesla’s 2014 decision to make its electric-vehicle technology open to competitors. It’s unclear what this new approach to patents means for the automotive industry, but when a major company like Toyota follows Tesla into the royalty-free patent space, it suggests a clear trend toward greater openness.

“The first generation hydrogen fuel cell vehicles, launched between 2015 and 2020, will be critical,” Carter said. “[Their launch will require] a concerted effort and unconventional collaboration between automakers, government regulators, academia and energy providers.”