"With lower CO2 limits, we can only burn LNG so demand will increase as we replace coal-fired plants," CPC Vice President S.H. Chu told Reuters in an interview.
As demand for LNG increases, Taiwan could potentially have room for up to two more LNG terminals, he said.
CPC will hold open tenders in the middle of the year for the four ships, each capable of carrying 146,000 cubic metres (5.156 million cubic feet) of gas, to supply the 4,000 megawatt Tatan power plant run by Taiwan Power Co in northern Taiwan, Chu said.
He said two ships would be delivered in 2009 and two in 2010. He estimated the price of each vessel at around $175 million. He did not mention possible suppliers, but they could include South Korea's Hyundai Heavy Industries Co and Daewoo Shipbuilding and Marine Engineering, the world's two biggest shipbuilders.
Taiwan is almost entirely reliant on imports to meet its LNG needs, with Indonesia supplying roughly 60 percent and Malaysia around 40 percent.
Last year, CPC won an US $8.7 billion, 25-year contract to supply LNG to the Tatan plant, undercutting foreign competitors, including a consortium led by Royal Dutch/Shell.
To supply the gas, CPC is spending T$25 billion ($786 million) to build Taiwan's second LNG terminal in the central port of Taichung, said Chu.
The terminal will have an annual capacity of 3 million tonnes and receive its first gas shipment in 2008, said Chu, adding CPC would lease vessels to bring in the LNG for the first year.
"There have been no delays in our schedule so far and we are confident that by January 1, 2008, we will be able to supply gas as our work is progressing on time," said Chu.
He said CPC had resolved a disagreement with the Taiwan government over the land lease for the terminal. The government had wanted CPC to move the receiving dock further out to sea within 10 years to reduce congestion.
Both finally agreed to move the dock if it disrupted more than 300 ships in the harbour every year, said Chu.
"We accept the 10 years as a principle, not a condition, and we already have a verbal agreement and expect to sign the lease agreement in February," said Chu.
Chu said rising LNG demand will increase the need for more terminals, suggesting Tatan harbour near the power plant or expansions at either CPC's existing Yungan terminal in southern Taiwan or Taichung harbour as possible sites.
Taiwan's annual consumption of LNG is forecast by CPC to increase to 9 million tonnes by 2010 from around 6.6 million tonnes at present, after Tatan is fully operational and as the government brings coal-fired power plants off-line.
The gas from the second terminal will be transported to Tatan power plant via a 140 km (87-mile) undersea pipeline, said Chu.
Qatar will supply LNG from the Ras Laffan Liquefied Natural Gas Co's (Rasgas) train five to Taiwan's second LNG terminal.
CPC will form joint ventures to buy the ships. It will own 45 and 49 percent of the ventures, with the Qatar Shipping Co holding 25 percent and the remainder going to the shipbuilder, said Chu.
Taiwan has only one other LNG receiving terminal, which has an annual capacity of 7.8 million tonnes per year.