Examples of these would include SolarPower or WindPower. However many WindTurbines you erect, they will have no impact on the how much Wind there will be in the future. You just can not overuse ObligateRenewables.
This is in contrast to the PotentialRenewables, or the NonRenewables. The former can be used as a Renewable, but can also be overused. The latter will run out eventually, regardless of how you use them.