Joule Unlimited Technologies Inc., a Bedford company focused on commercializing sustainable, carbon-neutral ­fuels, has formed a partnership with automaker Audi AG that includes an undisclosed investment in a Joule demonstration plant in New Mexico.

Audi will help Joule commercialize Sunflow E and Sunflow D, transportation fuels for the ethanol and diesel markets, Joule said. They are produced with sunlight and waste carbon dioxide.

A long-term goal for Audi is developing vehicles that run on carbon-neutral fuels. Joule will benefit from Audi’s expertise and global reach as well as from the strength of its brand, Joule’s press release said. Audi will have “a first mover advantage” as Joule’s exclusive partner in the automotive sector.

Joule’s chief executive, William J. Sims, said the relationship “brings us one step closer to our goal of delivering Liquid Fuel from the Sun to vehicles everywhere.”

Joule has a demonstration plant for Sunflow E in Hobbs, N.M. Joule is privately held and has raised more than $110 million in funding.