Singapore aims to raise at least S$1.5 billion via the sale of an inaugural green bond, according to officials.

Part of a sovereign and public sector issuance program worth as much as S$35 billion, the debt will be launched via a book-building process within the week, the Monetary Authority of Singapore said in a statement on Monday. The tenor will be either 30 or 50 years, with proceeds to fund expansion of the city-state’s electric rail network.

Both institutional and individual investors can purchase the bonds with the sale to be conducted via syndicate instead of an auction, it said.

Because variables such as tenor and size are set the day the bond is priced, “syndication enhances the government’s ability to issue across varied market conditions,” MAS said.

Singapore announced its plan to issue sustainable debt earlier this year and is joining countries including Hong Kong, France, and South Korea in looking to raise funds for environmental projects.

The city state laid out its standards for green bonds in June. Proceeds from issuance must adhere to widely-used guidelines and can be used for projects including improving energy efficiency, preventing pollution or natural resource management. Expenditures related to fossil fuels and nuclear energy won’t be allowed