The cost of reducing carbon dioxide in Japan by using bioethanol fuel will be 52 times higher compared with purchasing carbon dioxide emission-reduction credits overseas, according to a recent government study.

The estimate was calculated for the five-year period from 2008 to 2012, when signatories of the 1997 Kyoto Protocol on curbing greenhouse gases are required to reduce emissions of such gases, including carbon dioxide.

The estimate, drawn up by the Natural Resources and Energy Agency, shows there will be 5.91 million fewer tons of carbon dioxide in the five years as a result of the introduction of bioethanol, an alcohol based on crops.

However, 456.7 billion yen will be needed to make necessary changes at gas stations nationwide to handle the alcohol-based fuel, according to the study.

On the other hand, if Japan purchases emission-reduction credits overseas, the cost will be only 8.8 billion yen.

The Kyoto pact allows industrialized states to purchase such credits from nations with surplus emission quotas.

Last month, the Environment Ministry decided to make gasoline mixed with 3 percent bioethanol available at gas stations across the country starting in fiscal 2012.