An image of a solar bicycle station. (C)SANYO Electric Co.,Ltd.

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The city of Setagaya in Tokyo has long been active in supporting environmental conservation. It is now garnering attention for its introduction of eco-friendly electric bicycles and two Solar Parking Lots powered by solar cells and lithium-ion batteries. The initiative is part of the city's efforts to realize a low-carbon society.

Solar Pedal PowerThe Solar Parking Lots were designed by major home electronics maker Sanyo, and will open in March 2010. One is located at Sakura-josui Station on the Keio Line, a railway that runs through Setagaya Ward; the other near Sakura-shinmachi Station on the Tokyu Den-en-toshi Line. Both employ a system in which power generated by solar cells on the rooftop is supplied via a lithium-ion-battery system in the facilities' interior.

An Eneloop Bike. (C)SANYO Electric Co.,Ltd.

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There are two advantages to combining these two different power systems. The first is that the batteries store any excess power generated by the solar panels. The second is that electricity can be supplied even on rainy days or at night, when there is no sunlight to power the panels. The electricity generated by this system is used primarily for powering the facilities' lights and charging the electric-assist bicycles, but it can also be used to power emergency equipment in the event of a natural disaster or other emergency.

Another creation is the Eneloop Bike, a hit product featuring the company's Eneloop rechargeable battery technology. The bike's electric motor has a system for automatically switching between charging and providing additional power. When the rear brakes are engaged or the bike is coasting the motor functions as a generator, converting power for storage to the battery; when the rider attempts to travel up an incline, the motor automatically provides additional power to the wheels. This system allows the Eneloop Bike to travel 1.8 times farther per charge than previous models.

An image of the bike park to be built at Sakura-shinmachi Station. (C)SANYO Electric Co.,Ltd.

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A New Form of Urban TransportDespite being located in the heart of Tokyo, Setagaya has an abundance of nature, and the local government has long been proactive in its efforts to protect this environment. Encouraging the use of bicycles is a part of these efforts. There are already rent-a-cycle ports at the area's five major train stations, providing transportation in the form of over 1,400 bikes that can be rented for a fee.

The introduction of the Solar Parking Lot and Eneloop Bikes will take this effort even further. In addition to making it easier to climb Setagaya's many hills, the new bikes will encourage the use of bicycles among older residents and others who may have previously found the terrain challenging. Constructing bike parks that derive most of their electricity from solar panels will reduce carbon dioxide emissions resulting from the bikes' operation.

Sakura-josui Station and Kyodo Station on the Odakyu Line are two of the five major stations in the area; 40 Eneloop Bikes are available for rent at the former and 20 at the latter. Setagaya plans to continue increasing the number of electric-assist bicycles available to residents and visitors.

Similar systems have been set up at other locations in Japan, and as numerous Japanese companies are capable of building such systems, it is quite likely that parallel endeavors will be pursued throughout the country. This would represent a step forward for Japan's society-wide effort to realize low-carbon cities. (March 2010)