It will be a significant challenge in the supply chain. The issue of the clean fuel standard, specifically to your question...Currently, the trucking industry has no alternative to diesel fuel. We are not married to diesel fuel. It is a marriage of no other choice. Right now there is no infrastructure capacity for another fuel that's North American-wide that would allow a long-haul trucker to operate.
On February 26th, 2019. See this statement in context.