Grid operator TenneT's biggest green issuance to date scooped the award for the best corporate green bond of 2018.

The euro-denominated deal is composed of two tranches, raising a combined €1.25 billion ($1.5 billion).

The first, €750 million, tranche has a 16-year maturity and a 2% coupon. The second, €500 million, tranche has a 10-year maturity and a 1.375% coupon.

TenneT has been a regular green bond issuer since its first dual-tranche, €1 billion deal in 2015.

This is the second time the issuer has been recognised in Environmental Finance's bond awards – it previously won an award in the same category two years ago.

The issuer has now raised €6.75 billion in the green bond market, making it the 13th largest issuer.

"TenneT has been one of the true pioneers in the green bond market, having issued all their debt instruments in green guise," says Othmar ter Waarbeek, executive director for debt capital markets at Rabobank, one of the lead managers on the latest deal. "This is a natural consequence of their involvement in the energy transition in Germany and the Netherlands, and TenneT has shown great leadership in helping develop this market."

The proceeds of the bond will be used exclusively to finance projects relating to the transmission of renewable electricity from offshore wind power plants into the onshore electricity grid. ISS-oekom reviewed the TenneT framework and is of the opinion that it aligns with the Green Bond Principles.

"Projects funded by TenneT's green bond are good quality projects," said one of the judges. "It is a very important issuer, given the size, frequency, liquidity and long-term nature of its issuances."

The sustainability performance of the bond is measured by quantitative indicators and impact indicators.

This latest issuance emphasized TenneT's role as an example to other grid operators as to how to successfully issue a green bond and how to contribute to a more sustainable society.