Wartsila has released its 20DF dual-fuel engine for sale in the U.S. market. According to the company, the engine meets the strict emissions compliance criteria of the United States Environmental Protection Agency (EPA) Tier 4 and is now available to American shipowners and operators. The 20DF is described as a proven engine, and its release is in response to the growing demand for natural gas-fueled engines.
 
By extending the availability of dual-fuel engine technology, Wartsila said it now offers the American marine sector greater possibilities to select fuel that enables compliance with environmental legislation. In addition to the environmental benefits attained from burning gas, the choice of fuel can now be made on the basis of price and availability since the dual-fuel (DF) technology allows engines to use either natural gas or diesel oil.

Lars Anderson, vice president, 4-stroke at Wartsila Ship Power, stated: "The 20DF will further accelerate the adoption of LNG as a marine fuel in the U.S. The ability to meet EPA Tier 4 emissions requirements without the need for exhaust after-treatment, while at the same time increasing the safety and operational flexibility for LNG vessels, provides significant value to our customers."
 
The 20DF is a commercial duty, medium-speed, dual-fuel engine. Engines supplied to the U.S. market will operate primarily on natural gas, with marine diesel oil (MDO) as a pilot fuel or as an emergency backup fuel.

The 20DF power spans the range from 1,056kW (1,415HP) to 1,584kW (2,122HP) per engine.

 Wartsila's 4-stroke dual-fuel engine portfolio is described a having the widest power range in the market. The 20DF, 34DF and 50DF output ranges from 1056kW (1,415HP) to 17,550kW (23,515HP) per engine. The company has delivered over 1,000 dual-fuel engines. This portfolio of engines currently has over seven million operating hours.

The lean burn, low pressure dual-fuel engine technology utilizes a very low percentage diesel fuel as a pilot ignition source, amounting to about 1 percent of total energy. This contrasts with other gas engine technologies that employ a significantly higher percentage of diesel pilot fuel, according to Wartsila, which said its lean burn results in lower operational costs and reduced emissions.