One of the ways in which climate change may be mitigated, and domestic energy
security improved, is to create a new biofuel to power our cars and trucks that
does not rely on traditional petroleum sources. One such fuel, ethanol, is
already widely blended into gasoline in the US; another, biodiesel, is on sale
in many fueling stations as a standalone fuel for diesel engines. However, due
to concerns over the long-term sustainability of current production processes
for biofuels (and for ethanol in
particular),
researchers are investigating a so called “second-generation” of biofuels. These
include fuels that can be made from cellulose (the material that makes up
plants’ cell walls, and comprises most of the mass of a plant) as well as fuels
made from novel feedstocks, such as algae. My research in particular has focused
on one such second-generation biofuel, called biobutanol. Biobutanol has many
technical advantages over ethanol, but biobutanol has not been approved by the
Environmental Protection Agency (EPA) for use in road vehicles. In a recent
review, Slating and Kesan
discussed the regulatory
hurdles biobutanol must clear to be approved for everyday use.
There are many factors that determine whether the development of a new fuel will
be successful. Some of these factors are engineering ones, and include such
things as power output and energy density. Other factors involve government
regulations surrounding the fuel industry. As an engineer, it is easy to forget
that even if a new fuel is technically better than an existing fuel, it still
must pass regulatory muster before it can be distributed and sold. In the US,
there are two sets of regulations a fuel has to pass before it is considered an
acceptable fuel. As detailed in the paper, these are the Renewable Fuel
Standard (RFS2) enacted in the Energy Independence and Security Act (EISA)
of 2007 and the “Substantially Similar” rule in the Clean Air Act (CAA) of 1972.
The first of these creates a captive market and incentive to produce new
biofuels such as biobutanol, while the second effectively limits the amount of
new biofuels that can be blended into existing fuels, creating a tension that
the EPA is required to balance.
In 2005, the US Congress passed the Energy Policy Act which contained the first
Renewable Fuel Standard (RFS1). This standard mandated certain production
targets for “renewable fuels”, with “renewable fuels” having a very broad
definition. Unfortunately, this standard resulted in little change in the
market, due to the dominance of ethanol produced from corn, which was able to
satisfy the requirements outlined in RFS1. To correct this, Congress enacted the
EISA in 2007 which contained the RFS2. In the RFS2, there are four nested
categories of biofuels; in order from most restrictive to least restrictive
definitions, they are Cellulosic Biofuels, Biomass-Based Diesel, Advanced
Biofuels and Renewable Fuels. The definitions are nested such that any fuel that
meets the requirements of either of the first two definitions (i.e. Cellulosic
or Biomass-Based) also satisfies the definition for Advanced Biofuels and
Renewable Fuels. In addition to providing these more stringent definitions, RFS2
also provides yearly targets for biofuel production for each category, with more
restrictive categories making up a larger percentage of the whole as time progresses.
Yearly Targets for Biofuel Production as Specified in the EISA RFS2. Source: Stoel Rives LLP
Depending on the production process, biobutanol could fit into any of the
categories except Biomass-Based Diesel. This means that if biobutanol can be
classified in a more restrictive category than ethanol, it has the potential to
capture a large segment of the market, due to the minimum production mandates in
RFS2. If it cannot meet the more restrictive definitions, ethanol may fulfill
the requirements satisfactorily, removing the market for biobutanol. It is
unclear as of this moment which production process for biobutanol will prove to
be commercially viable (leaving aside the regulatory issues), and therefore it
is uncertain which category biobutanol might fall into.
Once a new fuel such as biobutanol is categorized according to the RFS2, it
still can’t be introduced into road vehicles without the approval of the EPA
under a second set of regulations set forth in the CAA of 1972. In the CAA,
Congress outlined the “Substantially Similar” principle, which states that any
new fuel cannot be sold unless it is “substantially similar” to the fuel used by
the EPA in its tests of road vehicles. If a new fuel cannot be fit into the
substantially similar protocol, the company must apply for a fuel waiver for
that fuel, or try to apply a previously granted fuel waiver to their fuel.
Biobutanol, therefore, has three potential paths to take through the Clean Air
Act - to comply with the substantially similar rule, as it is currently set
forth by the EPA; to try to fit into an existing fuel waiver; or, to apply for a
new fuel waiver. The easiest path to take would be to follow the substantially
similar rule, which limits the weight percent of oxygen allowed in the fuel.
However, this would limit the amount of biobutanol which could be blended in
gasoline to about 12%. If a company wanted to try to fit into an existing fuel
waiver, they could attempt to pass through a loophole in a waiver that was
intended for methanol; this could allow up to 16% biobutanol blended with
gasoline. However, there is no guarantee that the EPA would allow this fuel
waiver to be used for a fuel for which the waiver was not granted. Finally, a
company could choose to apply for a new fuel waiver; this process could take
years, and according to the analysis in this paper, has only a small chance of success.
With the regulations as they stand, the authors assert that revised regulations
are appropriate, so that society can reap the benefits of cleaner burning fuels
in the very near future. They suggest two changes that could considerably speed
the regulatory approval of new fuels. The simplest would be for the EPA to issue
a new “Substantially Similar” rule, allowing the use of higher blending amounts
of biofuels (such as biobutanol) which have been shown to reduce regulated
emissions. The authors’ other suggestion is for Congress to modify the Clean Air
Act, so that the EPA is forced to consider new fuel waivers in a more timely
manner, especially for fuels that satisfy the RFS2 mandates. Since this may not
occur in the near future, the authors’ strongly recommend the EPA to create a
new “Substantially Similar” rule.
DOI: 10.1111/j.1757-1707.2011.01146.x