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Tuesday, Aug. 9, 2011



Backup batteries for home on radar

Storage units touted to counter power outages, peak-time rates

Staff writer

Storage batteries — especially those for home use — have been gaining attention since the March 11 earthquake and tsunami crippled the Fukushima No. 1 nuclear plant and sparked fears of blackouts hitting Tokyo during another sweltering summer.

News photo
Juice on hand: NEC Corp. started marketing this battery-based power storage system for home use on July 18 amid public concerns that power outages might occur this summer because of the crisis at the Fukushima No. 1 nuclear plant and other reactor closures. NEC CORP.

Although large systems designed for industrial use are still mainly in the experimental stage, several home-use power storage systems are already on the market or on their way.

Given the seriousness of the disaster, use of the systems is expected to climb if prices drop enough.

Here are some questions and answers on storage batteries:

How do home-use storage battery systems work?

The systems are mainly designed to serve as an emergency power source for blackouts. At night, when utility charges are lower, people might want to charge them so they can provide power during peak daylight hours, when utility charges rise.

A typical home system would incorporate lithium-ion batteries in a box. The batteries can be recharged via the national grid, in many cases by just plugging the unit into ordinary household sockets. Others can be charged off rooftop solar panels.

The battery-based system includes an inverter to convert alternating current from the national power grid into direct current and also converts DC to AC to power home appliances.

Experts stress the importance of developing battery-based storage systems because they will help utilities boost the use of renewable energy sources, particularly solar and wind.

Because the weather is unpredictable, however, power generated from natural sources is undependable, they said.

What models are now on the market?

Manufacturers initially focused on corporate-use battery systems, but the disasters and the sporadic rolling blackouts that followed spurred demand for compact home systems. Also, there is growing demand for so-called smart homes featuring technological innovations.

NEC Corp. started selling a power storage system for homes on July 18.

On a full charge, the 76-cm-wide, 45-cm-deep and 88-cm-high unit provides 6 kw per hour.

The system, which can be connected to a power panel installed in a home, can automatically be recharged either via the grid or solar panels, and discharge power as needed. The retail price is ¥2.5 million.

NEC plans to sell 100 units this year and 10,000 annually starting in 2012.

Lithium-ion battery maker Edison Power on April 15 started to sell a lower-cost battery-based storage system to retailers. The system can be charged off power outlets. The 1 kw-per-hour model is priced at ¥800,000 and the 2.5 kw-per-hour model runs for ¥1.8 million.

Eliiy Power Co., a startup maker of lithium-ion batteries that has let corporate customers lease its Power Yiile since September, will start selling the product for home use this fall for ¥1.5 million to ¥1.9 million. The system provides 2 kw per hour.

Are there efforts to pare prices?

Yes. Some companies plan to market a power-storage system using cheap, second-hand batteries salvaged from electric vehicles, including 4R Energy, a joint venture involving Nissan Motor Co. and trading house Sumitomo Corp.

The venture said last month it plans to develop storage battery systems using second-hand lithium-ion batteries used in Nissan EVs.

According to 4R Energy, if a five-year-old Nissan EV has a low odometer reading, the original battery probably still has about 80 percent of its power storage capacity. These batteries can be removed and reused in the home, the company said.

"The existing battery systems on sale for households are too expensive," said 4R Energy President Takashi Sakagami after a news conference on July 11.

"The market will decide the price, but I expect we can cut the price because the batteries are second-hand," he said.

On its own, Nissan, according to recent reports, is working on a system that would allow its Leaf EV to be used as a power source for the home.

The Weekly FYI appears Tuesdays. Readers are encouraged to send ideas, questions and opinions to hodobu@japantimes.co.jp

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