The Renewable Fuel Standard is a federal government mandate requiring the use of specified levels of ethanol and advanced biofuels in transportation fuels, which was first introduced in 2005.
Until now, RFS requirements have been met almost entirely by blending gasoline with ethanol made from corn. However, once corn-based ethanol production reaches 15 billion gal., the law requires the use of increasingly large amounts of ;advance biofuels’, including diesel made from biomass, ethanol made from sugarcane and cellulosic biofuels.
The International Energy Agency (IEA) has highlighted that the increased requirements for advanced biofuels might be difficult to meet in future for several reasons:
- There is a lack of availability of cellulosic biofuels.
- There is nowhere for the ethanol to go because most vehicles can only use up to E10 (a gasoline biofuel blend containing 10% ethanol; most gasoline is E10) without voiding the cars’ warranties.
- Many small motors have problems with any ethanol volumes blended with gasoline.
According to the IEA, only a small number of production facilities have started to produce cellulosic biomass because making these fuels is complex, capital-intensive and costly. Cellulosic biofuels capacity has not, and is not expected to reach the levels required by law.
Increasing requirements on biofuels usage demands a much higher level of ethanol in gasoline, potentially as much as 25% by 2022. The use of such fuel in standard vehicles would cause engine damage.
‘Flex-fuel’ vehicles can run on blends of as much as 85% ethanol (E85), however less than 2% of fueling stations in the US sell high ethanol blends due to its limited demand. Demand is limited because E85 costs more for motorists.
Delayed decision making
The Environmental Protection Agency (EPA) has reduced the annual requirements for advanced biofuels in the RFS, in recognition of the problems with the 10% ‘blend wall’. However, these reductions have yet to be finalised despite being half way through the year.
The IEA highlights that the EPA has missed its deadline to set the required volumes of ethanol and biodiesel that must be blended into transportation fuels every year since 2009. This makes it difficult for refiners to plan and ensure compliance with mandates.
Adapted from a report by Emma McAleavey.
Read the article online at: https://www.hydrocarbonengineering.com/gas-processing/04072014/iea_rfs_852/