[4] By the end of 2001, Boralex had 200 employees and 18 sites in Québec, the United States and France, for a total installed capacity close to 350 MW generated by hydroelectric, thermal and gas- and wood-residue-fired cogeneration power stations.

Boralex continued its expansion in the wind power industry by entering the United States in 2003 with the acquisition of five small hydroelectric power stations in New York State, with a total capacity of 23 MW, and then in Canada with the commissioning in February 2010 of the Thames River wind farm, totalling 90 MW,[6] in Ontario.

Seigneurie de Beaupré began operating in 2013 with a total installed capacity of 272 MW, and remains one of the largest wind sites in Canada.

[7] At the end of 2012, Boralex terminates its natural gas cogeneration operations at Kingsey Falls, 22 years after the power station opened.

In 2017, the Caisse de dépôt et placement du Québec, one of Canada’s leading institutional investors, purchases of all Cascades’ Class A common shares, making them Boralex’s principal shareholder, with 17,3%.

Decostre was Boralex’s first employee in Europe, where he spent 18 years building the company’s footprint and established the first onshore wind farm in France.

He was notably named CEO of the Year, SME Category, by Les Affaires Magazine, and was ranked in the Top 100 Power People report, both in 2017.