First Reserve is a premier global energy-focused private equity and infrastructure investment firm with over $26 billion of raised capital since the firm's inception. First Reserve Corporation was founded in 1983 and is based in Greenwich, Connecticut with additional offices in Houston, Texas; Central, Hong Kong; and London, United Kingdom. The firm invests globally with a focus on Australia, Europe, and United States. It typically makes equity and equity related investments of between $100 million and $1500 million.

The firm seeks to invest in the energy and natural resource industry with a focus on energy manufacturing and oilfield services, power related companies, renewable and alternative energy, energy-related insurance and financial products, energy reserves, energy infrastructure such as firms that engineer LNG and natural gas processing facilities, renewable and other power, midstream, electric transmission and utilities. It also invests in technology, pipelines, and storage.