Had he continued working aboard fuel-powered cargo ships, Yann Jourdan reckons he'd be earning perhaps four times what he now gets as captain of a sailboat that instead uses the wind's clean energy to transport goods across the Atlantic. But the hit to Jourdan's pay is buying him peace of mind. When his 3-year-old son, Marcel, grows up, the burly French mariner wants to be able to explain what he did to make a dent in the the shipping industry's huge carbon footprint.