Sauté the green onions and garlic in a skillet coated with nonstick cooking spray over medium heat for 3 minutes. Add the broth, peanut butter, soy sauce, lemon juice, chili powder, brown sugar and ginger and mix well. Reduce the heat to low.
Simmer for 10 minutes, stirring frequently. Remove from the heat and let stand until cool. Add the shrimp and toss to coat. Marinate, covered, in the refrigerator for 1 hour or longer. Drain the shrimp, discarding the marinade.
Preheat the broiler. Thread the shrimp on metal skewers and arrange on a rack in a broiler pan. Broil for 4 minutes per side or until the shrimp turn pink.