Page 121 - Sustainable On-Site CHP Systems Design, Construction, and Operations

Regulatory Issues 99

The federal Clean Air Act of 1970 and its amendments that regulate air emissions from
stationary engines such as those used to power CHP systems is the most significant
emissions related legislation. The Clean Air Act required the U.S. Environmental Pro-
tection Agency (EPA) to establish ambient air quality standards to protect public health
and the environment. These National Ambient Air Quality Standards (NAAQS) are the
metric for the emissions compliance for CHP applications and have limits for six crite-
ria pollutants of which NO , CO, SO , and particulate matter (PM) are of the greatest
x 2
relevance to CHP systems (see Chap. 7). Most CHP systems employed today operate
with natural gas as the main fuel source so the criteria pollutant of most concern for
CHP systems is NO . Ambient air is classified by region as either “in attainment” or
x
“nonattainment” for a given pollutant. Areas that are in nonattainment for NO will be
x
required to meet lower emission levels than those areas that are in attainment and will
most likely require the addition of post-combustion treatment of exhaust to meet the
emissions requirements.
While the NAAQS are standards for ambient air quality, there are also equipment-
based performance standards and new source review requirements established by the
federal government but which are implemented by state authorities. CHP plant devel-
opers are required to apply for preconstruction environmental permits (see Chap. 12)
that will generally be categorized according to the annual volume of specific pollut-
ants that the proposed CHP plant has the potential to emit. The potential to emit is
calculated on the total emissions from the plant running at full output for all operat-
ing hours. Large plants that exceed certain total annual emissions thresholds are con-
sidered a major source. As such they are subject to regulation according to federal
standards as implemented by the state. Plants that emit less than these major sources
are subject to state regulated “minor source review” and small plants that are under
state specified thresholds may be exempt from permit requirements. Small plants and
minor source plants are generally subject to state regulations which are designed to
meet federal standards at a minimum but which may also be considerably more
restrictive than federal standards. The air permitting process is generally used to
define the type of pollution control device to be used in order that the CHP plant may
obtain a permit to construct and a permit to operate. In all cases the air permit require-
ments for CHP plants needs to meet federal standards as well as be in compliance
with local regulations.

U.S. State CHP Policy
As indicated above, the influence of the federal government on the development of
CHP in the United States is somewhat limited due to jurisdictional issues. The PURPA
regulations introduced in the late 1970s gave a strong boost to large-scale CHP for three
decades but the economic benefits provided by this federal legislation are no longer
available in most regions. Until the 10 percent investment tax credit recently enacted,
there has been little material support for CHP over the past three decades from the
federal government. The U.S Department of Energy has generally been sympathetic to
CHP and has implemented various CHP-related research and demonstration programs,
but has been prevented from providing significant material support due to budget
appropriations for CHP being relatively small.
In trying to overcome the many roadblocks that prevent wide implementation of
CHP it has become apparent that the individual states play a much more significant role