Carol Newby's search for bags of wood pellets to fuel the family pellet stove took her on a tour of Southern New Hampshire last week, with little success. "We usually get them at the local Agway," she said, "but they were in short supply and what they had was committed to customers who'd made pre-buys." She was able to get a few bags at the Lowe's in Epping, but when she went back, they were out. After coming up empty at tractor supply stores in Epping and Hooksett, she tried a nearby Home Depot, which also had no pellets to...