U.S. artificial intelligence-driven energy storage company Stem Inc. is nearing a deal to go public through a merger with blank-check acquisition company Star Peak Energy Transition Corp. at a valuation of around $1.35 billion, according to people familiar with the matter on Dec. 3.

The agreement could be announced as early as Dec. 4, the sources said, requesting anonymity ahead of an official announcement.

Stem was founded in 2009 and provides an energy storage system which allows users to automatically switch energy usage between battery and grid power, based on an artificial intelligence platform dubbed “Athena”. Its backers include Activate Capital, BNP Paribas and GE Ventures.

Batteries are used to solve the issue of the intermittent nature of renewable energy sources such as wind and solar. Pairing big batteries with renewable energy projects improves reliability without creating climate-changing emissions.

Star Peak is a special purpose acquisition company (SPAC). A SPAC is a shell company which raises funds in an IPO with the aim of acquiring a private company, which then becomes public as result of the merger.

Star Peak raised around $350 million in an IPO in August on the NYSE with the aim of buying a business focused on the transition to newer sources of energy. Star Peak’s chairman is Mike Morgan, the lead director of U.S. pipeline operator Kinder Morgan Inc.

SPACs have emerged as a quick route to the stock market for companies, particularly auto technology startups, which are seeking to eschew the lengthy IPO process.