South China's Yunnan Province Tuesday put its second transnational power transmission project into operation and expected to send an annual 400 million kwh of electricity to Vietnam.

It is the country's largest transnational power transmission project, said sources with the Yunnan Power Grid Corporation, adding that it will inject vitality into Vietnam's economic and social development.

The electricity is generated and sent from the Maomaotiao Hydropower Station, located in the Wenshan Zhuang and Miao Autonomous Prefecture, through the 28-km-long power transmission line.

The province now has a power transmission capacity of 133,000 kw to Vietnam, with annual electricity transmission reaching over 400 million kwh, the power grid corporation said.

The province started the first transnational power transmission project in September 2004, and had sent electricity totaling 129 million kwh by May of this year.

The corporation forecast that by 2010, Yunnan will develop transnational power transmission capacity to one million kw.

According to agreements with the ASEAN, Yunnan will still send electricity to Thailand between 2006 and 2010, with transmission capacity hitting 3 million kw.