Retiring some existing coal-fired
plants and replacing their output with cleaner resources
is the key to maintaining or lowering carbon dioxide
emissions from the regional electric sector, according
to a new Northwest Power and Conservation Council
State renewables portfolio standards, substantial
energy conservation and summer-spill elimination
are insufficient to significantly slow or reverse
the rising trajectory of regional power-related
CO2 emissions, according to "Carbon Dioxide Footprint
of the Northwest Power System," released Sept.
"CO2 production from electricity generation is
dominated by existing coal-fired generating plants,"
the paper said. "To stabilize CO2 production at
2005 levels or to reduce CO2 production to 1990
levels would require substituting low CO2-producing
resources or additional conservation for some
of these existing coal-fired power plants.
"In addition, the scenario analysis shows that
policy choices that are made for purposes other
than CO2 reduction (in this case fish and wildlife
policy) can also have significant effects on CO2
production; enough effect to negate policies such
as renewables portfolio standards," it said.
The council analysis estimated that regional
CO2 emissions from the Northwest electric system
have risen from about 44 million tons in 1990--a
popular baseline year for climate-change policies--to
67 million tons in 2005. Economic growth, added
fossil-fueled generators, diminished hydro capabilities
and closure of the Trojan nuclear plant near Portland
all contributed to this trend, the council said.
The study also noted that had 2005 been a normal
water year as was 1990, CO2 emissions in 2005
would have been about 59 millions tons, a 34-percent
increase over 1990.
Looking ahead, the council projected that if
regional resource development follows its 2004
plan emphasizing renewables, conservation and
some natural gas, CO2 production by 2024 would
amount to 71 million tons, representing a 20-percent
gain over 2005, assuming normal water conditions
"It's really easy to go up [with CO2 emissions]
and it's really difficult to go down . . . is
what appears to be happening," said council senior
resource analyst Jeff King, at the Aug. 14 meeting
of the council's Power Committee.
To return to 1990 CO2 levels or below, "you have
to address the existing stock of coal-fired resources
to achieve that kind of objective," he said. From
2015-2024, under the council's recommended resource
portfolio, coal would account for 81 percent of
Northwest power system CO2 production.
The Northwest, whose total capacity is close
to two-thirds hydropower, fares well in CO2 emissions,
relative to the greater West. Under normal water
conditions in 2005, the region's power system
would have emitted about 540 pounds of CO2 per
megawatt-hour generated, compared to about 990
pounds/MWh for the Western Electricity Coordinating
Council area, the council figured.
However, it noted, all regions possess "essentially
the same set of future resource options," and
consequently, "it will be difficult for the Northwest
to maintain or reduce its CO2 emissions rate."
If state renewables portfolio standards were
met in Washington, Oregon and Montana, and all
summer spill were eliminated to enable more hydro
generation, the growth rate of CO2 emissions would
only be lowered an estimated 60 percent, the council
"Failure to achieve the conservation targets
in the Fifth Power Plan, or removing the lower
Snake River dams and replacing the power in a
manner consistent with the Fifth Power Plan, could
more than offset the potential savings from the
scenarios that reduce CO2 production," the paper
The four federal dams on the lower Snake River
generate about 1020 aMW of energy under current
river operations, and provide 2650 MW of sustained-peaking
capacity, according to the council.
The effect of their removal on regional CO2 emissions
depends on the replacement resources, taken in
the study to be 810 aMW from new and existing
gas plants, and 170 aMW from existing coal units.
This would raise average annual CO2 production
4.6 millions tons over the council plan's resource
scenario from 2015-2024.
Making up the loss of the hydro generation from
the lower Snake dams with a market-purchase scenario
was considered but not reported. The council said
this approach "would compromise system adequacy
and reliability by reducing the amount of resource
available to meet load."
Another potential scenario involves conservation
and renewables as the main substitute resources,
a notion promoted by the Northwest Energy Coalition,
among others, in support of dam-breaching as a
This approach could delay some CO2 increases,
but not stop or reverse it, the council paper
Tying the increased development of conservation
and renewables to dam breaching is "misleading,"
it said, because this means discarding more than
1000 MW of "emission-free generation" that must
eventually be replaced, "unless the supplies of
renewables and conservation are considered unlimited."
However, given the difficulty of reducing CO2
emissions, discarding existing CO2-free power
sources has to be considered "unproductive," it
Steve Weiss, policy analyst with NWEC, told the
council's Power Committee last week that conservation
and renewables as dam resource-replacements would
not all be cost-effective, but added that he expected
Congress to "make the region whole" and not increase
costs specifically to Northwest electric ratepayers
if it does authorize dam removal.
Weiss also said keeping the dams, in various
spill scenarios, "doesn't change the CO2 problem
The council asked its staff to forecast CO2 production
using an assortment of future resource scenarios.
The base case corresponded to the council's latest
plan, while other scenarios were based on low
conservation gains, high renewables development,
or utility integrated resource plans.
Lower Snake dam removal and spill effects were
Under all these scenarios, regional CO2 emissions
rose in 2024 from the 59 million tons emitted
in 2005, an average water year. The lowest level
was the high-renewables scenario, at 66 million
tons in 2024, while the highest was the utility
IRPs, at 77 million tons.
"The purpose of these alternative scenarios is
to quantify the sensitivity of results to plausible
changes in the power system and some related policies
that have received attention," said the paper.
"No new council position on any of these policies
is intended by this analysis, nor should any be
Comments on the paper are due Oct. 19. The paper
is available at www.nwcouncil.org/library/2007/2007-15.htm