POWER February 2016 - 19

COMBINED HEAT AND POWER
Steel City Steam
Like many large cities in the northeastern
U.S., Pittsburgh has a district heating system
in its downtown areas. And, like those
other cities, Pittsburgh's system is quite
old: It's been operating for more than 100
years. Overseen by Pittsburgh Allegheny
County Thermal (PACT), the system currently
serves about 65 buildings in the
Golden Triangle area of downtown, including
all of the area's city, county, state, and
federal office buildings.
The PACT system isn't the only district
heating system in Pittsburgh, either. Another
one, owned and operated by NRG,
serves the area on the north side of the
Allegheny River. According to David Gaier,
senior director of communications for NRG's
East Region, that system serves about 6.3
million square feet of space, including
important regional landmarks such as the
Allegheny General Hospital, PNC Park, and
the Carnegie Science Center.
Pittsburgh sits in the heart of the Marcellus
shale region, and it consequently
enjoys some of the lowest natural gas
prices in the country. That makes it an
ideal candidate for expanding its CHP
capacity. Last summer, the city signed a
memorandum of understanding with the
National Energy Technology Laboratory
on joint efforts to design modern energy
infrastructure for Pittsburgh. One key element
of that initiative was supporting
and expanding opportunities for district
energy systems, and the first target was
the city's district heating systems.
" While these energy systems have served
us well for decades, they're terribly inefficient, "
area Congressman Mike Doyle
(D-Pa.) said at the time. " That means we're
producing more pollution and greenhouse
gas emissions than we need to. " Pittsburgh
and PACT turned to NRG for help.
where existing onsite electric loads can be
served at facilities conducive to CHP. Another
110 GW of potential exists in sizing CHP systems
for industrial thermal loads, leading to
exports of electricity to the surrounding grid.
CPP = CHP
Pressure to deploy more CHP is coming, in
part because of that route to substantial efficiency
gains. The biggest driver-assuming
it survives judicial review-will be the EPA's
Clean Power Plan (CPP).
February 2016 | POWER
1. Deep heat. NRG's district heating
(DH) system in Pittsburgh is part of a
planned project to upgrade the city's aging
DH network with more-efficient infrastructure
and a new cogeneration plant. Courtesy:
NRG Energy
" We've been engaged by the City to
develop ways to improve and expand the
100-year-old PACT steam system covering
downtown, " Gaier told POWER via email.
" With 80 or so customers, the idea is to
retain current customers and add new
ones. NRG has a solid, progressive vision
for Pittsburgh District Energy: development
of and collaboration among three
systems-the existing NRG district energy
system, the PACT system, and the future
Lower Hill District system " (Figure 1).
NRG and CJL Engineering are jointly
developing the Lower Hill District system
just east of the Golden Triangle, Gaier
said. " In the plan, a new district energy
plant will be located adjacent to the Consol
Energy Center, and the UPMC Mercy
Hospital would be the anchor customer. "
The project will ultimately include a fullscale
CHP plant on the site and begin operations
in 2017.
Upgrading the PACT system will help
improve its efficiency and reduce its emissions,
and the collaboration with NRG will
create one of the largest district heating
systems in the country.
" Whether your state follows a mass-based
or rate-based approach to compliance under
the CPP, CHP would be able to contribute, "
Hampson said. Under a rate-based approach,
a CHP plant's lower emissions per megawatt
compared to conventional generation could
enable the plant owner to generate emissions
rate credits that it could sell to higher-emitting
sources. " That could provide another revenue
stream to the CHP plant, " she said. " Under a
mass-based approach, it would have a very
similar type of thing, except instead of selling
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credits, it would most likely sell into something
like an allowance market. "
Though the CPP is often thought to offer a
substantial boost to gas-fired power, a study
from EPRI released in October 2015 suggests
that CHP could provide a way for advanced
coal-fired plants to meet EPA emissions limits
without carbon capture, again because of
the efficiency gains that would result. (See
" CHP and Other Technologies Could Breathe
New Life into U.S. Coal-Fired Power Plants "
in this issue for details.) The caveat, however,
is that a 750-MW advanced ultrasupercritical
plant would require at least a 150-MW thermal
load to achieve 12.5% extraction, and the
number of potential customers who need that
much steam is limited. The study suggests
that smaller coal-fired CHP plants-similar
to Spiritwood Station-are more likely to be
viable under the CPP.
Another report, which ICF helped prepare
for the Pew Charitable Trusts, " Industrial Efficiency
in the Changing Utility Landscape, "
looked at potential growth in the CHP market
through 2030. Though CHP in general is
poised to expand, growing 12.4 GW by 2030,
the combination of the CPP and some improved
tax treatment of CHP could result in
30% more capacity: 16.1 GW by 2030. The
biggest gains in absolute terms would accrue
in California and Texas, both states with
substantial industrial bases that are potential
customers for CHP output.
State-Level Support
California and Texas also illustrate the possibilities
for state-level policy support to affect
CHP adoption. Both states have substantial
unexploited CHP potential. Another report,
by the Brattle Group, estimates the potential
in Texas at around 11 GW, and up to 20 GW
by 2032 as a result of continued growth in
the petrochemicals industry. Texas took a
big step in that direction recently by making
it easier for CHP plants to sell electricity to
adjacent customers without being considered
utilities.
California, meanwhile, has a state policy
to add at least 4 GW of new CHP capacity by
2020. That's been a bit controversial because,
while CHP is more efficient than conventional
generation, it's still typically powered
by natural gas, which means greenhouse gas
(GHG) emissions. With the state also under
a mandate to reduce those emissions, environmentalists
have pushed to cut support for
gas-fired CHP. Renewable CHP, meanwhile,
is getting some attention (see the sidebar
" Bakersfield Biomass " ).
But CHP-heavy states like California and
Texas are not the only places where the technology
has a growing future.
New York has promoted CHP for years,
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POWER February 2016

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