Tachikawa wind farm
by the CADDET Japanese National Team

Tachikawa wind farm.

The Japanese town of Tachikawa-machi began exploiting its local wind resource for power generation in the early 1990s. Since then, wind turbines have become a symbol of the town and its commitment to the use of renewable energy. The citizens aim to generate enough electricity from wind and other renewable energy sources – some 22,000 MWh/year – to supply annual power demand in the town by 2005. As of March 2000, nine wind turbines had been built, with a total capacity of 3,500 kW capable of generating a total of almost 6,600 Mwh/year.

Introduction

The town of Tachikawa-machi, in northeastern Japan, is located at the pivot of the fan-shaped Shonai Plain, a major rice-producing area which spreads westwards towards the Sea of Japan. Between spring and autumn a strong east-southeasterly wind, known locally as the Kiyokawa-dasi, blows through the town, frequently damaging crops and sometimes causing fires.

In addition to the seasonal, east-southeasterly Kiyokawa-dasi, strong winds from other directions contribute to a monthly mean wind speed of around 5 m/s, when averaged over the last 10 years. For 88.5 days in each year, the town experiences winds with speeds exceeding 10 m/s.

In 1995, the town established a plan to generate some 22,000 MWh/year of electricity – the annual power requirement of the town – from natural energy sources, especially wind. As of March 2000, nine wind turbines with a total installed capacity of 3,500 kW had been completed. Expected to produce 6,570 MWh/year, these will supply 30% of annual power consumption in Tachikawa-machi.

Until recently, Japan had fallen behind Europe and North America in the exploitation of wind energy. However, the installation of wind turbines is growing very rapidly and the country’s total wind power increased from 17 MW in 1997 to more than 100 MW in 1999. Within this context, the Tachikawa-machi project represents a pioneering example of large-scale wind power development in Japan.

First steps

Some small-scale experiments to test the use of wind energy for agricultural purposes were carried out from 1980–85, but the very small (1 kW and 5 kW) turbines proved no match for the region’s winds. However, the projects provided valuable experience, allowing the inhabitants of Tachikawa-machi to recognise the potential usefulness of the local wind. When, in the late 1980s, the Japanese government gave a grant worth JPY 100 million (where JPY is the Japanese yen) to every town and village for local development projects, the people of Tachikawa-machi seized the opportunity to turn the “windy nature” of their town to their advantage.

“Fusha-mura” – the wind turbine village – was built and three 100 kW wind turbines, manufactured by the US company KWI, were installed to symbolise the town’s first step towards true exploitation of wind energy.

Towards full-scale exploitation

In 1995, the town council decided to increase its commitment to full-scale exploitation of wind energy by establishing a “New Energy Introduction Plan”. This aimed to satisfy the power demand in Tachikawa-machi wholly through exploiting its renewable energy sources, mainly wind, by 2005.

In January 1996, two 400 kW wind turbines were commissioned on a large rice field in the town. Installed as part of a joint venture by six businesses, this was the first attempt to generate wind power commercially in the town.

A Danish company, NEG-MICON, manufactured the upwind-type wind turbines with forced yaw control. The 31 m diameter, three-bladed rotor is mounted on a tower at a hub height of 36 m.

The turbines run smoothly at an availability factor of 56% and a load factor of 17% for most of the time. They generate 1,200 MWh/year – thereby saving fossil fuel consumption equivalent to

292 kl/year of oil (see Tables 1 and 2). The cost to construct the 400 kW machines was JPY 310,000/kW; power generation cost is JPY 15/kWh.

In 1998, the town invested in a joint venture to build four 600 kW NEG-MICON wind turbines, completing two in May 1999 and the remaining two in March 2000. Each turbine has a 48 m diameter, three-bladed rotor tower-mounted at a hub height of 46 m. The four wind turbines achieved a relatively high capacity factor of 27% and 34% in February and March 2000 respectively, once early operating problems had been solved. With the wind turbines running smoothly, about 5,200 MWh/year of electricity can be generated, saving fossil fuel consumption equivalent to 1,270 kl of oil. The total wind power generating capacity of Tachikawa has increased to 3,500 kW, enabling the town to generate a total of 6,570 MWh/year – 30% of its annual power consumption – and saving fossil energy use equivalent to 1,600 kl/year of oil.

The 600 kW machines cost JPY 290,000/kW to build, with half the investment cost in the equipment covered by a central government subsidy. This financial support, combined with lower construction costs and higher output, reduces the power generating cost of these turbines to JPY 11.5/kWh.

Looking ahead

Figure 1: Annual wind speeds in Tachikawa-machi (at a height of 15m from the ground)

In the future, the residents of Tachikawa-machi intend to exploit other renewable sources to help meet their energy needs. There are plans to introduce a 10 kW photovoltaic power generation system for use in greenhouse cultivation and to develop small-scale hydro power generation on nearby rivers.

Since 1987, the town has run a recycling plant where household refuse, farmyard waste and rice hulls are turned into compost for agricultural use. Through community effort, the people of Tachikawa-machi are determined to play a part in helping to  protect the environment, by recycling and the exploitation of local renewable energy sources.

For more information contact the CADDET Japanese National Team in Tokyo.

The CADDET Renewable Energy Newsletter is a quarterly magazine published by  the CADDET Centre for Renewable Energy at ETSU, UK.

The articles published in the Newsletter reflect the opinions of the authors.  They do not necessarily reflect the official view of CADDET.

Enquiries concerning the Newsletter should be addressed to Pauline Toole, Editor, CADDET Centre for  Renewable Energy, ETSU, Harwell, Oxfordshire OX11 0RA, United Kingdom. Tel: +44  1235 432968, Fax: +44 1235 433595.