Windstream was awarded a feed-in tariff contract from Ontario in May 2010 for its C$5.2bn Wolfe Island project, located 5km-16km off the northeastern coast of Lake Ontario, and the developer went on to sign a turbine supply agreement with Siemens Canada.

But the following year, amid mounting political pushback against Ontario’s high-cost renewables strategy, the province unexpectedly issued a moratorium on all offshore wind development off its coasts, citing a need for further environment studies.

Rather than suing Ontario directly – like Trillium Power, another developer, did – Windstream sued Canada for C$568m, saying the moratorium violated its rights under the North American Free Trade Agreement (NAFTA), by expropriating its investment without a clear reason for doing so.

Windstream