U.S. energy czar en route to Bulgaria SOFIA, Bulgaria, Feb. 6 (UPI) -- The U.S. envoy for Eurasian energy is on his way to Sofia to discuss Bulgarian energy initiatives, the U.S. secretary of state said. Bulgarian Prime Minister Boyko Borisov met with U.S. Secretary of State Hillary Clinton in Sofia to discuss Bulgaria's role with NATO as well as energy security. Clinton said Washington supports the country's energy diversification and independence strategies. "We are partners in helping to advance Bulgaria's energy independence and security and in protecting the beautiful Bulgarian environment," she said in a statement. Sofia last month imposed a moratorium on the hydraulic fracturing of shale natural gas deposits. Sofia estimates there's enough shale gas in the country to last a millennium, though authorities had said the extraction procedure wasn't safe. In terms of conventional natural gas, Bulgaria would host part of the planned Nabucco pipeline meant to deliver non-Russia gas supplies to European consumers. Clinton said Richard Morningstar, U.S. special envoy for Eurasian energy, was en route to the country to discuss Sofia's energy options. Morningstar told the Interfax news agency in December that Washington was a key supporter of the pipeline. Nabucco would be "preferable" but it must be commercially viable, he said. Borisov had said Bulgaria considered most renewable energy projects too expensive to pursue.