Even in parts of the country where the population has been growing, electricity sales have been anemic. Retail sales to homes and businesses still are less than they were in 2007, before the recession. Photo: Bloomberg News The long-term future of the nation’s electric grid is under threat from an unlikely source—energy-conserving Americans. That is the fear of some utility experts who say that as Americans use less power, electric companies won’t have the revenue needed to maintain sprawling networks of high-voltage lines and generating plants. And if the companies raise rates too high to make up for declining sales volumes, customers will embrace even more energy-saving gizmos and solar panels, pushing down demand for grid power. The Edison Electric Institute, the trade group for investor-owned utilities, has warned that they could face a “death spiral.” “Utilities seem to have concrete shoes on,” says Elisabeth Graffy, co-director of […]