Producing power from the wind and sun isn’t as simple as just swapping a wind turbine for a coal-fired power plant. Every source of power we use has to work with our electrical grid, an old, imperfect, complex system that wasn’t put together with the needs of renewables in mind. For instance, because renewable generation is intermittent generation, using it goes hand-in-hand with ramping production from traditional generation up and down. When you don’t have enough wind, you turn up the gas-fire generators. That kind of treatment can put stress on machinery and rack up costs in maintenance and repairs. But new research from the National Renewable Energy Laboratory suggests that, at least in monetary terms, those costs are dwarfed by the cost savings you get from using more wind and solar power and, thus, not having to pay for fuel sources.