Google has teamed up with the German insurance company Allianz and a Swedish wind-farm developer called O2 in a deal to provide wind energy for the internet company's new data center in Hamina, Finland, for the next 10 years.

This is Google's fourth long-term renewable-energy-purchase contract and its first such deal in Europe. O2 will build a 72MW wind farm in northern Sweden, whose entire electricity output will go to the Google data center for a decade.

Such a multinational agreement would not be possible without Scandinavia's integrated electricity market and grid system called Nord Pool, Francois Sterin, senior manager for Google's global infrastructure team, wrote in a blog post. “It enables us to buy the wind farm’s output in Sweden with Guarantee of Origin certification and consume an equivalent amount of power at our data center in Finland,” he wrote.

Allianz is financing the entire construction project and will become the wind farm's owner once it comes online in early 2015. Google's long-term purchase agreement is what helped O2 get the financing.

The Hamina data center is famous for its innovative energy efficient design, whose most distinctive feature is its cooling system. The building used to be a paper mill and had a large tunnel that brought seawater from the Baltic Sea for cooling.

Google retrofitted the tunnel to use seawater in the cooling system for its data center.

Google has done similar power-purchase deals for its data centers in Oklahoma and Iowa. In each case, the company helped a wind-farm developer finance construction of a wind-generation project by committing to purchasing the future wind farm's entire energy output for an extended period of time.

In Oklahoma, the company contracted in 2011 to buy all power from a 100.8MW wind farm for the following 20 years. In 2010, Google signed a 20-year power-purchase agreement with a developer of a 114MW wind farm in Iowa.

In addition to acting as a customer, the internet giant also invests in renewable-energy projects around the world. Back in Iowa, the company bought a $75m equity stake in an operating wind farm.

In April 2011, the company invested $5m in a photovoltaic power plant in Germany. Just last week, the company announced its first investment in Africa: a $12m cash infusion into a 96MW photovoltaic plant in South Africa.