Geoscience Reference
In-Depth Information
sources (and major modifications of existing sources) that emit more
than a threshold amount of GHGs.
In September 2011, EPA promulgated GHG emission standards for
model year 2014-2018 medium- and heavy-duty trucks.
In October 2012, the agency promulgated a second phase of GHG
emission standards for cars and light trucks, covering model years
2017-2025.
3
As extensive as these actions may seem, they have had relatively minor
impacts on GHG emissions to date. The rules are prospective, and in most
cases have not yet taken effect.
The auto and truck manufacturing industries have been the major focus of
the GHG regulations; in both cases, they are eager to improve fuel economy
(coincidentally reducing GHG emissions), because the high cost of fuel has
affected consumer purchasing decisions over the last five years. Almost
without exception, the major companies in these industries have supported
EPA's GHG standards.
The stationary source permitting requirements have yet to affect most
sources. EPA and the states issued fewer than 50 GHG permits to stationary
sources in the year following the requirement's implementation, because the
emission threshold for requiring permits was set at a high level, and because
few new facilities were being constructed in the recession's aftermath.
4
Ultimately, if EPA is to reduce the nation's GHG emissions, as the
President has committed to do, it will have to issue emission standards for
broad categories of existing stationary sources. EPA took the first step toward
setting such standards on April 13, 2012, with the proposal of standards for
new electric generating units (EGUs). In a June 25, 2013, memorandum to the
EPA Administrator, the President directed the agency to re-propose those
standards by September 20, 2013, finalize them ―in a timely fashion after
considering all public comments,‖ and develop guidelines for existing EGUs
by June 1, 2015.
5
As shown in Table 1, EGUs—principally, coal-fired power plants—are
the most significant U.S. source of greenhouse gases, accounting for about
one-third of the nation's total emissions. With the principal mobile source
categories already subject to GHG regulations, EPA will have addressed the
sources of more than half of all U.S. emissions once it promulgates regulations
for existing EGUs.
