Web giant Google has bought its first offshore wind power, adding output from a project off Belgium to its massive global procurement portfolio from onshore wind and solar.

Google will take 92MW-worth of output from the Norther wind farm in the Belgian North Sea under a deal with Engie, which markets power from the 370MW project that's currently completing construction.

The deal is Google's first for wind at sea. Google's EU energy lead Marc Oman told Recharge last year that offshore was was increasingly on its radar, thanks to the steep cost reductions seen in the sector over recent years.

The power will be used for Google's Belgian data centre. Google Belgium director Thierry Geerts said: "Modern offshore wind turbines can be more than twice the size of onshore wind turbines, allowing us to bring large quantities of clean, low-cost electricity to the grid where our Belgian data center is located."

The offshore wind deal came as Google unveiled what it billed as the biggest corporate renewable power purchase in history with 1.6GW of agreements it said would spur $2bn of solar and wind development on three continents.

Google – which claims to be the leading procurer of renewable energy globally – signed up for output from 18 development-stage projects it said brings its renewables agreement total to 5.5GW globally.

The power deals also include a hybrid wind and solar project in Chile, representing the first of its kind for Google.

Google CEO Sundar Pichai said: “Up to now, most of our renewable energy purchases in the US have been wind-driven, but the declining cost of solar (down more than 80% in the past decade) has made harnessing the sun increasingly cost-effective.”

Google, Facebook and Amazon are prominent among a clutch of US technology giants leading the corporate procurement of green energy.