The US Constitution specifically authorizes eminent domain....and specifies that the property thereby appropriated will be paid for at a fair price to the owner. Eminent domain has been so horribly abused over the years, from making George Bush rich to cities handing private homes to private developers to increase municipal tax revenues that clearly the prescience of the Founding Fathers is once again demonstrated. Politicians are corrupt.
But guess what? "General welfare" does not mean "fund any, or all, socialist looney toon ideas the left comes up with."