| dc.description.abstract |
The composition of the U.S. electrical power system reflects competing objectives,
as investments are driven by ratepayers who demand access to electricity that is both
low cost and reliable. Maintaining generation ready for fluctuations in demand currently
requires the inefficient use of generation assets, driving up total energy system
costs. During the night, low demand for electricity can force the underutilization
of wind farms and baseload coal-fired plants. During the day, load-following natural
gas-fired plants are often operated at partial capacity so they can be ramped up to
track changing demand. One means to address these two issues is electricity storage.
Electricity storage technologies are capable of shifting surplus low cost nighttime
electricity to times of higher daytime demand. Whether time-shifting electricity storage
technologies may enable lower energy system costs depends upon the parameters of these
technologies and future conditions. In this study, a least-cost optimization energy
model (MARKAL) managed by U.S. EPA is used to explore the potential future role of
electricity storage under varying conditions. Scenarios model a stricter national
renewable portfolio standard (RPS), varying natural gas prices, and a national limit
on CO2 emissions from the energy system. Scenario results are analyzed to discern
the impact of electricity storage on generation output and on the associated energy
sector emissions of CO2, SO2, NOx, and PM10. Four trends emerge when examining the
impacts of time-shifting electricity storage on the national energy system. First,
electricity storage enables an increasing utilization of baseload generation and a
corresponding decreasing reliance on daytime load-following generation. Second, and
to a lesser degree, nighttime natural gas-fired generation increases, making use of
existing capacity. Third, the overall decreasing natural gas use by load-following
generation leads to the increasing use of natural gas in the industrial sector. Fourth,
the use of time-shifting electricity storage does not result in net increases of electricity
output from renewable power sources. The impacts of these four trends on generation
investments and emissions vary by the future conditions modeled. In many instances
the use of electricity storage results in a less expensive energy system with higher
emissions of CO2, SO2, NOx, and PM10.
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