Energy giant Neste is deciding whether to locate a renewable-diesel refinery here or in the United States, according to the Finnish firm's boss.

President and chief executive Matti Lievonen said the group expects to come to a final decision on the location by the end of next year.

Neste's existing renewable-diesel plant in Singapore is the largest in the world, boasting a capacity of 1.1 million metric tonnes a year.

The firm also runs a similar facility in Rotterdam in the Netherlands, and two smaller units in Porvoo, Finland.

Mr Lievonen, who was speaking at the 10th anniversary of the company's Tuas plant, said the upcoming refinery will be bigger than its existing ones, with more complex operations. In addition to renewable diesel, it will focus on bio-jet fuels, a fast-growing market.

He would not be drawn into commenting on how Singapore is faring in the race, but said Neste is considering a host of factors, such as how the location's business chains will fit in with its operations, the availability of feedstock sites, talent, as well as support for the business.

Mr Lievonen noted that its $1.2 billion Tuas refinery has performed very well, recording a 30 per cent jump, equal to a 300,000 tonne growth in capacity, over the last four years.

The facility produces Neste MY Renewable Diesel, which can be used in engines to achieve up to 90 per cent less greenhouse gas emissions than with fossil diesel.

Most of the renewable diesel from the plant goes to the product's main markets in Europe and North America.

Mr Lievonen said: "The Neste Singapore refinery is helping reduce greenhouse gas emissions by three million tonnes annually.

"The reduction is equal to the permanent removal of 900,000 cars from the roads. This is a great achievement for a company and the environment.

"Today, people... are becoming more and more aware (of the need for cleaner fuels), and there is immense demand."

Overall net sales last year hit €11.7 billion (S$18.6 billion).

Minister for Trade and Industry (Industry) S. Iswaran told the anniversary gathering that Neste's investment here in 2007 was "not only an ambitious and strategic move... but also a strong vote of confidence for Singapore as a destination for high value-added manufacturing".

"Today, Neste Singapore serves several key markets across the world. This is enabled by Singapore's well-connected air and sea links, as well as extensive network of free trade agreements.

"In particular, Neste has benefited from our strong trade links with developed economies, such as the US and Europe, in serving the demand from these markets."