One of the fleet of the world's first switchable-battery electric taxis rolls through a battery switching station in Tokyo. The world's first switchable-battery electric taxis hit the streets of the Japanese capital in a government-funded pilot project to test the emission-free cars.

The world's first taxis with easily replaceable batteries hit the streets of the Japanese capital Monday in a government-funded experiment.

The purpose-built cars that can run on easily swapped batteries -- rather than wait to be recharged or switch to other fuels -- were launched in Tokyo by Japan's energy agency.

Three cars based on the Nissan Dualis will operate as normal taxis on the city's streets during the 90-day experiment, a joint project with Better Place, a US firm specialising in providing electric vehicle infrastructure.

"Tokyo can become the capital of ," said Kiyotaka Fujii, president of the Japanese unit of Better Place.

Ordinary Tokyo taxis can clock up as many as 300 kilometres (186 miles) a day, the company says, and the city is by far the world's largest market with 60,000 cabs -- more than New York, Paris and London combined.

While taxis represent only two percent of all passenger vehicles in Tokyo, they emit about 20 percent of all (CO2) from vehicles.

"By building a good business model, we believe this technology can have a significant impact on the economy and society," Japanese energy agency official Minoru Nakamura told a press conference.