California is again at the forefront of the battle against climate change with a new mandate that could soon go into effect.

The state has just passed a mandate requiring new big rigs and other trucks to have zero emissions by 2040. It would join a recent ruling which bans sales of gas-powered cars in California by 2035.

The new proposal is intended to phase out high-pollution diesel to something that more closely matches the state’s dedication to a zero emissions future.

Transportation remains California’s greatest emissions source, pumping out greenhouse gases, smog, and other air pollutants.

A senior vice president at the California Trucking Association says that while truckers are enthusiastic about the potential for zero emissions technology, they worry about “the practical unknowns,” which include the high initial investment of buying a new (and more expensive) truck, a lack of charging stations readily available for engines as large as they need, and limited ranges – all technology issues plaguing electric vehicles in other transportation-related industries as well.

The VP, Chris Shimoda, said, “We’re flying blind into some pretty major questions about the practicality of actually implementing this rule.”

California’s air board will hold a public hearing on the proposed mandate on October 27, after a 45-day public comment.