Malta, the renewable energy storage project born in Alphabet’s moonshot factory X, is now on its own and flush with $26 million from a Series A funding round led by Breakthrough Energy Ventures .

Concord New Energy Group and Alfa Laval also invested in the round.

Project Malta launched last year in Alphabet’s X (formerly Google X) with an aim to build energy storage facilities that can support full-scale power grids. The independent company spun out of Alphabet is now called Malta Inc.

Malta Inc. has developed a system designed to keep power generated from renewable energy or fossil fuels in reserve for longer than lithium-ion batteries. The electro-thermal storage system first captures energy generated from wind, solar or fossil generators on the grid. The collected electricity drives a heat pump, which converts the electrical energy into thermal energy. The heat is stored in molten salt, while the cold is stored in a chilled antifreeze liquid. A heat engine is used to convert the energy back to electricity for the grid when it’s needed.

The system can store electricity for days or even weeks, Malta says.

Malta is going to use the funds to work with industry partners to turn the detailed designs developed and refined at X into industrial-grade machinery for its first pilot system.

BEV, the lead investor in Malta’s Series A round, was created in 2016 by the Breakthrough Energy Coalition, an investor group that includes Microsoft co-founder Bill Gates, John Doerr, chairman of venture firm Kleiner Perkins Caufield & Byers, Alibaba founder Jack Ma, Amazon founder and CEO Jeff Bezos, and SAP co-founder Hasso Plattner.