Wireless recharging on the move

Researchers have developed new technology and techniques for transmitting power wirelessly from a stationary source to a mobile receiver.

The research, conducted at North Carolina State University, could lead to so-called highway ‘stations’ that can recharge electric vehicles wirelessly as the vehicles drive by.

‘We’ve made changes to both the receiver and the transmitter in order to make wireless energy transfer safer and more efficient,’ said Dr Srdjan Lukic, an assistant professor of electrical engineering at NC State and senior author of a paper on the research.

The researchers developed a series of segmented transmitter coils, each of which broadcasts a low-level electromagnetic field. The researchers also created a receiver coil that is the same size as each of the transmitter coils, and which can be placed in a car or other mobile platform.

The researchers modified the receiver so that when it comes into range and couples with a transmitter coil, that specific transmitter coil automatically increases its current – boosting its magnetic field strength and the related transfer of energy by 400 per cent. The transmitter coil’s current returns to normal levels when the receiver passes out of the range of the transmitter.

These modifications are claimed to improve on previous mobile, wireless power transfer techniques.

One previous approach was to use large transmitter coils, but this approach created a powerful and imprecise field that could couple to the frame of a car or other metal objects passing through the field. Because of the magnetic field’s strength, which is required to transfer sufficient power to the receiver, these electromagnetic field ‘leaks’ raised safety concerns and reduced system efficiency.

Another previous approach used smaller transmitter coils, which addressed safety and efficiency concerns. But this approach would require a very large number of transmitters to effectively ‘cover’ a section of the roadway, adding substantial cost and complexity to the system, and requiring very precise vehicle position detection technology.

‘We tried to take the best from both of those approaches,’ Lukic said in a statement.

Lukic and his team have developed a small, functional prototype of their system, and are now working to both scale it up and increase the power of the system.

Currently, at peak efficiency, the new system can transmit energy at a rate of 0.5kW. ‘Our goal is to move from 0.5kW into the 50kW range,’ Lukic said. ‘That would make it more practical.’

The paper, ‘Reflexive Field Containment in Dynamic Inductive Power Transfer Systems,’ is published online in IEEE Transactions on Power Electronics.

Source: http://www.theengineer.co.uk/energy-and-environment/news/wireless-recharging-on-the-move/1017546.article#ixzz2lrEKfB8T

Spinach power could provide electricity

Apparently Popeye the Sailorman isn’t the only one who can get a boost from spinach.

As far back as 1929, the cartoon character was using spinach for an energy boost that would power his “fisks”. Now five engineering students fromVanderbilt University in the US have shown us just how powerful spinach can be, by turning it into a biohybrid solar cell.

Over 40 years ago, scientists discovered that one of the proteins involved in photosynthesis, known as Photosystem 1 (PS1), could continue to function after it was extracted from various plants, including spinach. From this, they determined that PS1 converts sunlight into electricity with nearly 100 per cent efficiency — unlike manmade devices, which had efficiencies of less than 40 per cent.

Since this first discovery, scientists have been slowly and steadily developing ways to extract the protein and use it to produce long-lasting, electricity-making solar cells — not an easy task. “Nature knows how to do this extremely well. In evergreen trees, for example, PS1 lasts for years,” says associate professor David Cliffel, one of the team’s mentors. “We just have to figure out how to do it ourselves.”

His team developed a way to combine the PS1 from spinach with silicon, a material currently used in solar cells. They extracted the protein into an aqueous solution and poured the mixture on the surface of a p-doped silicon wafer, before evaporating the water to produce a one-micron-thick film of protein.

Their design, reported in the journal Advanced Materials, produced substantially more electricity than has been previously reported for biohybrid cells — nearly a milliamp (850 microamps) of current per square centimeter at 0.3 volts. That’s nearly two and half times than the best levels achieved by previous cells.

The next step is to create a functioning PS1-silicon solar cell using this design. And thanks to a US$90,000 grant from the EPA at the 8th Annual National Sustainable Design Expo, the team is on its way. “If we can continue on our current trajectory of increasing voltage and current levels, we could reach the range of mature solar conversion technologies in three years,” Cliffel says.

The five students also won the Marketplace Innovation Award from Paladin Capital and the Student Choice Award at the Expo for their innovation. “The team absolutely excelled in clearly presenting their engineering innovations to the public, says professor Kane Jennings, the team’s other mentor. “We were one of only two teams (out of 44) to win three awards.”

Source: http://scienceillustrated.com.au/

Plastic: The new material for solar cells

Professors Nunzio Motta and John Bell use world-standard super microscopes in the race to develop cheap plastic solar cells for mobile devices.

QUT's research to develop cheap plastic solar cells to charge mobile phones and other electronic devices has been boosted with the installation of one of the most powerful nanotechnology microscopes in the world.

The only one if its kind in Australia, the Zeiss Orion NanoFab enables researchers to examine natural or manmade structures in incredible detail, and will create new insights wherever it is applied.

By increasing the microscope beam current, researchers are able to etch away material to create patterns or structures with features of only a few nanometres. This is a tool that can write lines 100,000 times finer than the text on a printed page. Imagine War and Peace etched on the head of a pin - 200 times over.

QUT nanotechnology expert, Professor Nunzio Motta, said the new microscope complemented QUT's existing tunnelling microscope, the only one of its kind in Queensland, and would cement the university's place at the cutting edge of Australiannanotechnology research.

He said the super microscopes would be used to create new nanostructures which could be used in electronic devices, solar cells, gas sensors and for a range of other uses.

"At the moment plastic solar cells are quite inefficient and researchers around the world are trying to determine how to make the cells efficient and able to be commercialised," Professor Motta said.

"The advantages cheap solar cells would produce would be enormous.

"In the future plastic solar cells could generate enough energy not only to recharge the batteries of laptops and mobiles, but even to obtain power from canopies on parking areas which could be fed back into grids.

"They could even be developed as a clear film on glass windows to produce power."

Professor Motta is currently using the tunnelling microscope to improve plastic solar cells by mixing them with graphene, an atomic-scale honeycomb lattice made ofcarbon atoms

. He has found that adding gold nano-particles traps light and improves efficiency.

"While it's difficult to put a timeframe on the development of efficient plastic solar cells, a five to ten year goal is probably not unrealistic," he said.

Professor Motta said his research team also hoped to create a new class of solar-powered nano-sensors capable of detecting pollution and monitoring the environment in remote areas.

He said nanoscale science was critical to the world's future economy as advances would transform a range of scientific and engineering disciplines.

Professor Motta said QUT was organizing NanoS-E3, an International Workshop and School on nanotechnology at Airlie Beach in September.

Source: phys.org