I would think saving the planet would be motivation enough.
That only works on the truest of true believers.
But if nothing else, I think the US government should fund and subsidize the shift to a new energy infrastructure, through research grants, tax incentives, etc.
Using money to motivate people. That works.
In a larger scope, it is interesting to me that profit is the only way we can think of to motivate people. It's as if we weren't creative beings at heart. Absent the profit motive, I think people would create and build things out of necessity, creativity, or a desire to make life better for oneself and others. Profit is actually a poor motivator because a well-done job or quality product is only a by product of a desire for profit. If a profit can be made with shoddy work or an inferior product, that's just as well; because the motivation is profit, not doing a good job.
You don't need to motivate people to do what they already want to do. But they're probably already doing that, so how will you get anyone to change?
The US government has shown that it will come up with large amounts of money when properly motivated. We need a Manhattan Project
In WW2, the US was attacked. This is an obvious motivating factor. Climate change is something with ambiguous consequences in the distant future. "Something bad might happen someday" isn't really similar to "we're under attack".
If you give up on using money, you can only motivate change by telling a convincing story or threatening people. That's why people focus on money.