Pictures: A New Hub for Solar Tech Blooms in Japan

Zeroing In on Solar Power Efficiency

Photograph courtesy of JFE Engineering

The 87 heliostats of the Solar Techno Park's HyperHelios system are designed to track the movement of the sun and then concentrate the collected sunlight on a receiver installed atop a 20-meter (65-foot) tower.

This tower-type Concentrating Photovoltaic (CPV) power system produces twice the generation efficiency of conventional silicon panels, thanks to its unique arrangement of heliostats mounted with about 800 circular mirrors, along with a lens-like receiver that directly generates electricity from solar cells installed right behind the lens.

The receiver, which can become extremely hot from the concentrated sunlight, is cooled by a circulating water system that applies technology JFE has developed for its steel business. The water recirculates between the solar cell module and the cooler to minimize water use.

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Published March 7, 2012

Space-Age Solar Tracking

Photograph by Koichi Kamoshida, Bloomberg via Getty Images

Eighty of the heliostats in the Solar Techno Park's HyperHelios CPV system have circular mirrors that use tracking sensors to follow the sun, while seven other heliostats have flat square mirrors with programmed movement. The circular mirrors were developed by Mitaka Kohki, a Japanese manufacturer of high-precision instruments for space research institutions such as NASA and Japan's Institute of Space and Astronautical Science. The heliostats use the same tracking sensor technology as solar telescopes.

Though the mirrors are treated with protective coating, JFE said it will need to develop a device that can automatically clean the mirror surfaces because the clarity of the mirrors directly affects the apparatus's ability to collect sunlight.

Published March 7, 2012

Transforming the Sun's Heat

Photograph courtesy JFE Engineering

Solar Techno Park's concentrating solar thermal power (CSP) system uses the same configuration as that of the HyperHelios system, seen here from the ground below. Heliostats collect solar energy and channel it to a receiver at the top of a 20-meter tower.

But instead of converting sunlight, the CSP receiver gathers the sun's heat, which is then used to generate hot steam. In a working power plant, that steam would drive a turbine, producing electricity in the same way as other thermal and nuclear plants. Solar Techno Park's testing-only setup does not have the costly turbine required to convert the steam for electricity generation.

Such a system, when fully operational, would be suitable for large-scale power generation and could store heat to allow for power generation around the clock. Because a CSP system can use only sunlight that directly hits a mirror, JFE's technology will more likely provide revenue as an export to sunnier climes, as opposed to providing energy at home in Japan.

The company is also working on combining the advantages of the CPV and CSP systems to create a more cost-effective and efficient tower-type power generator that can be used at night and on cloudy days.

Published March 7, 2012

Thermal Power Impervious to Wind

Photograph courtesy JFE Engineering

The Linear Fresnel concentrating solar thermal power system shown here can generate steam of up to 450°C (842°F) by concentrating solar heat on linear collecting tubes installed 2 meters (6.5 feet) above a row of flat mirrors. The simple structure has the advantage of being relatively low-cost and unaffected by wind compared to a conventional parabolic trough system, which uses a similar array of curved mirrors.

JFE Engineering licensed the technology from German developer Solar Power Group in 2011 for exclusive sales rights in Southeast Asia, but the system has yet to be installed in any Japanese facility, and JFE is primarily focused on selling the Linear Fresnel technology to overseas markets. Although solar thermal power is known to be more efficient than conventional photovoltaic systems, Japan lacks the vast land area and dry, cloudless weather needed for CSP plants. The country experimented with solar thermal power in the 1970s and 1980s, but failure to produce substantial results put a halt to further research in the field until recently.

Another reason for the lack of commercial interest in domestic CSP: Japan's new feed-in tariff (FIT) policy, which will require utilities to buy electricity from renewable energy sources at preset rates starting in July, does not have provisions for solar thermal power. The scheme offers solar energy producers long-term contracts at above-market prices to reflect the higher cost of solar generation, while allowing utilities to bill a surcharge to customers.

Published March 7, 2012

Efforts to Heat Up an Industry

Photograph by Koichi Kamoshida, Bloomberg/Getty Images  

Before it opened Solar Techno Park, JFE had begun developing the HyperHelios system as part of a June 2010 commission from Japan's Environment Ministry that was focused on counteracting global warming. But the nuclear crisis has created a new urgency for the development of renewable energy in Japan. With the cooperation of Mitaka Kohki and the Institute of Applied Energy, JFE finished installing the tower CPV system at its Yokohama facility in August 2011.

The solar market continues to be a challenge. Once-thriving Japanese solar panel manufacturers have suffered in the wake of lower-priced competition from China. But the newly passed FIT incentives, which will go into effect in July, stand to boost an industry that is already benefiting from Japan's altered energy landscape. For JFE, the payoff in solar could go beyond hedging its own bets on the recovery of Japan's power grid. The company invested more than 300 million yen ($3.7 million) to develop and build Solar Techno Park; it is targeting solar industry sales of at least 50 billion yen ($610 million) by 2015.

Published March 7, 2012