By Timothy Gardner

WASHINGTON, July 19 (Reuters) - TAE Technologies, a private company hoping to revolutionize electricity generation with nuclear fusion, said on Tuesday it has raised $250 million in its latest funding from new investors like Chevron and existing ones including Google.

California-based TAE has raised $1.2 billion to date for research in fusion, the same process that powers the sun. It sees non-radioactive hydrogen-boron as the ideal fusion fuel.

Fusion works when nuclei of two atoms are subjected to extreme heat, leading them to fuse into a new larger atom, giving off enormous amounts of energy in the process.

The extreme heat takes a lot of energy when starting up, one hurdle for fusion. Another is that the heat must be contained economically in a power plant.

TAE says that it has achieved temperatures of more than 75 million Celsius (135 million Fahrenheit) with its research reactor, called Norman, and that the new money will fund construction of its next research reactor, Copernicus.

Global interest in fusion is rising as the need to cut carbon emissions increases.

"The caliber and interest of our investors validates our significant technical progress and supports our goal to begin commercialization of fusion by the end of this decade," said Michl Binderbauer, CEO of TAE Technologies.

Chevron invested an undisclosed amount in TAE through its Technology Ventures, a unit focusing on energy innovation.

"TAE - and fusion technology as a whole - has the potential to be a scalable source of no-carbon energy generation and a key enabler of grid stability as renewables become a greater portion of the energy mix," said Jim Gable, vice president for innovation and president of Chevron Technology Ventures.

Alphabet's Google, which has partnered with TAE since 2014 on computational artificial intelligence and machine learning, also invested an undisclosed amount.

Founded in 1998 and formerly known as Tri Alpha Energy, TAE Technologies operated in stealth mode for years, drawing the interest of investors including Venrock, brokerage Charles Schwab and the Kuwait Investment Authority. (Reporting by Timothy Gardner; Editing by Bradley Perrett)