NEW YORK/BOSTON, Sept 17 (Reuters) - Riverstone Holdings LLC, one of the oil and gas sector's largest private equity investors, is planning a blank-check acquisition company that will buy a business in the clean energy industry, people familiar with the matter said on Thursday.

The move illustrates how some private equity firms that have placed big bets on hydrocarbons, a sector battered by low oil prices and rising investor awareness of climate change, are increasingly focused on deploying capital into greener projects.

A buyout firm founded 20 years ago by Goldman Sachs Group Inc veterans, and which is backed by the investment bank, Riverstone is in the process of establishing a so-called special purpose acquisition company (SPAC), the sources said.

The new entity will raise money from investors in an initial public offering (IPO), which will form the basis of a war chest to buy a privately owned clean energy business, the sources said. A formal announcement about the venture could come as soon as October, two of the sources added.

Riverstone declined to comment.

Many clean energy companies have sought mergers with SPACs in recent months, a move allowing them to go public at a time when either their own operations or the technology they use is still in the early stages of development.

Investors have poured cash into SPACs buying such firms, hoping their investment can become the next Tesla Inc, the electric vehicle startup that is now the world's most valuable automaker.

Riverstone's SPAC will be the buyout firm's fourth such entity, the previous three being oil and gas-focused. The trio raised between $450 million and $1.04 billion at their respective IPOs, and the latest is expected to be in the same range, one of the sources said.

The firm's previous SPACs have had mixed results.

Centennial Resource Development Inc, an oil producer in the prolific Permian basin, was worth more than double the Riverstone SPAC's IPO price as recently as October 2018, before subsiding investor support for the U.S. shale sector dragged down the company's valuation.

Alta Mesa Holdings, an Oklahoma-focused producer, filed for bankruptcy in September 2019, less than two years after Riverstone's second SPAC completed its $3.8 billion merger with the company.

Despite its oil and gas heritage, Riverstone has also deployed significant money into the renewable energy space for more than a decade. Among its bets was Pattern Energy, which was bought earlier this year by Canadian pension fund CPPIB in a deal worth $6.1 billion including debt. (Reporting by David French in New York and Joshua Franklin in Boston Editing by Matthew Lewis)