There are currently more than 60,000 taxis cruising around Japan, a number that accounts for 20 percent of the country's CO2 emissions. To promote environmental health, the Japanese government has joined with Better Place, a US firm specializing in electric vehicle development, to come up with a solution: electric taxis powered by replaceable batteries. Today, three of the taxis will begin their circuit during a 90-day experiment funded by Japan's energy agency.