America’s largest machine — the power grid — has been pumping lifeblood electricity from power plants to our homes and businesses for more than a century. The vast network of wires, switches, transformers and other technology has gone through periodic upgrades, but the infrastructure is aging and increasingly prone to blackouts. Unfortunately, the stress on the network is starting to show at exactly the time when we need it to shoulder and move thousands of megawatts from new wind farms and solar installations popping up all over the country.