Backup generators have been around for decades, what is new about on-site power generation?
Recent developments have pushed to make on site power generation cleaner, cheaper, and quieter. Backup generators typically use internal combustion engines with a multitude of moving parts and relatively high emissions of pollutants NOx and SOx. Microturbines have been developed which have very low emissions of pollutants and extremely few moving parts making them attractive from an environmental and maintenance point of view. Gas turbines are also being marketed in smaller capacities so that they have appeal beyond large utilities and factories. Fuel cells continue to be developed with a promise of higher efficiencies and lower emissions than any other source of electricity and heat. Finally, strides are being made to reduce emissions from IC engine driven generators to reduce their environmental impact.