Hawaii’s second-largest ocean cargo transportation firm plans to modernize much of its fleet with two to four new ships that will run on cleaner-burning liquefied natural gas.

Pasha Hawaii announced Wednesday that it is close to finalizing a contract to build two new ships that it expects to be ready for service in 2019 and 2020. And a deal, which the company said is being discussed with two U.S. shipyards, would include an option for an additional two ships.

Selecting one shipyard for the work is expected in January, Pasha said.

The order would provide Pasha with newer and bigger ships that can expand the company’s existing fleet of six ships or be used to replace older ships and maintain its fleet size. Pasha did not specify whether it will discontinue use of any older ships, and a company representative could not immediately address the question.

New ships also will make the company more competitive with dominant carrier Matson Inc., which in August said it placed a $511 million order for two new ships slated for delivery in 2019 and 2020. Matson also expects to take delivery of two new ships in 2018 and 2019 as part of a $418 million order placed in 2013.

Matson’s newest ship order calls for those ships to have engines that will run on fuel oil with a capability to be adapted to run on liquefied natural gas, also known as LNG.

Pasha said its new vessels will be the first to operate in Hawaii from the mainland on LNG from the start, and will dramatically reduce environmental impacts and increase fuel efficiency.

The company said LNG compared with traditional fuel oil cuts pollutants such as sulphur oxides, nitrogen oxides and particulate matter by as much as 90 to 100 percent while cutting up to 25 percent of carbon dioxide emissions from engine exhaust.

“We are fortunate to have shipyards within the United States that are very capable of building best-in-class cargo ships, including LNG powered vessels, competitively,” George Pasha IV, company president and CEO, said in a statement.

Pasha’s two new ships will be able to carry more containers than any of its existing ships, four of which are 36 years old and were acquired as part of Pasha’s $142 million acquisition of the Hawaii operations of former competitor Horizon Lines last year.

The expected new ships will have a capacity of 3,400 TEUs, or the equivalent of 3,400 20-foot containers. Pasha said this capacity includes 500 45-foot containers and 400 refrigerated containers.

Pasha’s four older ships have capacities of 2,300 to 2,400 TEUs. Pasha, a subsidiary of California-based The Pasha Group, began Hawaii service in 2005 with one new ship that can carry 2,500 vehicles. Last year before the Horizon acquisition, Pasha added a $200 million new ship with a capacity of 1,400 TEUs and 1,100 vehicles.

“Since entering the Hawaii shipping business in 2005, Pasha Hawaii has made and will continue to make significant capital investments to support our expanding customer base and the local business community as a whole,” George Pasha said in his statement. “In addition to increasing capability for our customers, these new ships will represent a new era in shipping for Hawaii in terms of greatly reduced emissions and increased efficiency.”