But the renewable fuel standard, as the requirements are commonly called, also allows refiners to opt out of that requirement by purchasing credits called Renewable Identification Numbers, or RINs, as offsets.
RINs are generated on a per-gallon basis by refiners that blend renewables into the fuels they produce. Typically, those refiners generate far more RINs than they need to meet their required obligations, and place excess RINs on a market where they are bought by other refiners that don’t blend renewables into their fuel, to be used as offsets.
The EPA also allowed refiners who don't blend renewables to obtain waivers if they could show they couldn't afford to meet that offset requirement, and offers extensions of waivers in subsequent years, where appropriate.
Over the years, prices for RINs have fluctuated, based upon supply and demand. Their value increased dramatically in early 2020, as refiners everywhere curtailed operations after motorists started driving less to adhere to travel restrictions imposed as part of the nation’s response to COVID-19.