SIEMENS

Semprius’ newest modules (illustration) have achieved a record 34 percent efficiency.

Photovoltaic manufacturer Semprius, which is based in Durham, North Carolina, has achieved a record efficiency of 33.9 percent with its high concentration photovoltaic (HCPV) modules. This record was measured under standardized test conditions in a joint project with the Instituto de Sistemas Fotovoltaicos de Concentración and the University of Madrid. Classic photovoltaic modules made of monocrystalline or polycrystalline silicon currently achieve an efficiency of around 20 percent and 16 percent, respectively. The highly concentrated photovoltaic modules from Semprius have a glass covering with integrated lenses. The lenses focus rays of sunlight, making it possible for them to operate with much less semiconductor material in each photovoltaic panel than conventional technologies. The panels are made of an inexpensive substrate on which small solar cells about the size of a pencil point — around 0.5 mm2 — are positioned. Lenses concentrate incident sunlight by a factor of about 1,000, and the resulting heat is conducted away through the substrate. In order to work properly, however, such modules must be used in conjunction with trackers that follow the sun throughout the day. This type of solar cell is ideal for use with direct sunlight, for example in desert environments. Instead of transferring the cells chip by chip, Semprius uses its patented micro-transfer printing process, which inexpensively applies up to one thousand cells per step. The cells are made of multiple layers of light-absorbing III-V semiconductors such as gallium arsenide that actually achieve an efficiency of 41 percent in the laboratory. Siemens has a stake in Semprius and wants to develop the technology further. High-volume commercial production of the modules is scheduled to begin in mid-2012.

New magnetic materials may reduce the need for rare earths.

Many products such as electric motors and high performance magnets rely on rare earth metals, 97 percent of which currently come from China. Siemens and RWTH Aachen University in Germany have launched a joint research project aimed at developing methods and processes for extracting such materials efficiently with low environmental impact. Siemens is providing €6 million in funding for the strategic collaboration — which is the company’s first university-based research program in this area. Plans call for at least nine doctoral candidates to conduct their research in this field over the next four years. Taking part in the collaboration are four departments from RWTH Aachen University, the Jülich research center in western Germany, and experts from Siemens’ Industry Sector. Siemens wants to reduce dependence on scarce or expensive raw materials such as rare earth metals, and is using different approaches in parallel to achieve this goal. For example, scientists at Siemens Corporate Technology are also working on strategies for more efficient use, recycling, and substitution of such materials. They are analyzing existing supply-related risks and developing new materials and recycling processes.

The new switch operates at 1.2 million volts.

At its plant in Aurangabad, India, Siemens has developed the world’s first circuit breaker capable of operating at 1.2 million volts. Ultra-high voltages increase the transmission capacity of power cables, thereby making it possible to transport large amounts of electricity over long distances with a relatively small number of overhead lines. Circuit breakers are used in transformer substations to connect or disconnect individual transmission lines. The new circuit breaker is destined for a test installation in Bina, India. The Indian government is turning to ultra-high voltage (UHV) technology in order to supply metropolitan areas with electricity that has been generated at distant locations in the country’s mountainous regions. The 1.2 megavolt test transmission line is capable of transmitting 8,000 megawatts of power. It therefore has more than twice the capacity of the 800-kilovolt lines that are currently in use. Alternating voltages of over one million volts and direct voltages of over 800 kilovolts are both classified as ultra-high voltages. Transmission at such high voltages reduces power losses and is therefore more efficient.

New OLED produces a record 32 lumens per watt.

A flexible organic light-emitting diode (OLED) from Osram has set a new efficiency record. Like LEDs, OLEDs are materials that convert electricity into light. But whereas LEDs emit light from a point, the luminous plastics in OLED panels emit light over an area. OLED products in the form of light tiles have been around for two years. Flexible versions are still being developed. Now, Osram researchers have produced a flexible OLED that emits white light from a surface measuring 11 by three centimeters. The unit generates 32 lumens per watt of electricity, making it more efficient than a halogen lamp. This record-breaking efficiency value was measured under nearly realistic conditions and without any lenses or other devices to increase light yield. One of the technical challenges associated with the design of flexible OLEDs involves protecting the sensitive luminescent layer — which is just half a micrometer thick — against oxygen and humidity. This has been achieved using a special thin film process and a flexible steel foil that is as thin as a sheet of paper and replaces the glass sheet at the back of the unit.

Passengers get a front-row view on Paris’s automated Line 1.

Paris’ metropolitan transport authority (RATP) is switching its Metro’s Line 1 to fully automatic operation — which means its going driverless. Siemens is responsible for the modernization of the automation technology. The new system is more energy-efficient than those with drivers and makes it possible to shorten the intervals between trains from 105 to 85 seconds. Line 1 is the most heavily traveled Metro line in Paris, transporting approximately 725,000 passengers per day to attractions such as the Louvre and the Arc de Triomphe. Installation of the line’s control technology and telecommunication system, adaptation of the rail vehicles, and equipment for the new control center are all taking place in parallel without disrupting normal operations. At present, the old trains are being replaced, one by one. In March 2012 there were 14 driverless trains in service on Line 1. By early 2013 all 49 of the line’s new Metro trains are to be equipped with automation technology, bringing service up to full transport capacity. It will then be possible to adjust the train frequency flexibly as needed.