IEEE Power & Energy Magazine - November/December 2021 - 68

significant new wind, solar, and battery energy storage. The
existing gas fleet, running at low capacity factors, would provide
balancing energy. For these low-carbon grids to become
a reality, it is not enough to demonstrate technical and economic
feasibility. Policy and regulatory changes would also
be required and will be discussed.
Shifting the focus to the near-term urgency of deploying
large amounts of wind and solar energy reveals the role of transmission
in decarbonization. Findings are presented from recent
work that highlight the role of transmission in integrating high
shares of variable generation across large geographic areas. The
work also demonstrates how transmission allows for blending
the complementary production profiles of wind and solar.
A similar energy transition underway in Europe is examined
from a continental point of view, with an emphasis on
Germany. Europe has de-emphasized clean, firm sources of
power, such as nuclear or carbon capture and sequestration,
and is placing major emphasis on renewable energy. The
approach increases the coupling between the power system
and renewable energy-produced fuel systems (hydrogen and
synthetic fuels) to decarbonize other sectors, including transportation,
buildings, and industry.
Plummeting Solar, Wind, and
Battery Costs Can Accelerate
Our Clean Energy Future
Dramatic reductions in the costs of solar energy, wind energy,
and battery technologies have the potential to accelerate the
timeline for economic power sector decarbonization. " The
2035 Report " used the latest cost data and industry-standard
modeling tools and forecasts to demonstrate the feasibility
and affordability of achieving 90% U.S. carbon-free electricity
by 2035. The study used industry-leading modeling tools
and data, including the National Renewable Energy Laboratory's
(NREL's) Regional Energy Deployment System
(ReEDS) tool for capacity expansion, Energy Exemplar's
PLEXOS production cost model, and cost and performance
forecasts from NREL's Annual Technology Baseline data.
The study compared two key cases, a No New Policy case,
which assumed the current energy policy is unchanged through
2035, and a 90% Clean case that assumes a federal clean energy
standard (along with complementary policies) that mandates
90% carbon-free energy by 2035. (See Figure 1.) In comparison,
the No New Policy case achieves only 53% clean electricity
in 2035. In the 90% Clean case, all coal plants are retired by
2035, and no new fossil fuel plants are built. The 90% Clean
case cuts carbon emissions by 1.3 billion tons in 2035 compared
to the No New Policy case, cumulatively 15.5 billion tons
from 2020 to 2035. Nearly 1,100 MW of new wind and solar
resources are online by 2035 in the 90% Clean case, providing
70% of the annual generation. Hydropower and nuclear provide
an additional 20% of carbon-free generation, and natural gas
plants drop to 10% (from 38% in 2019). The wind and solar generation
sources are supported by 150 GW of 4-h battery energy
storage, providing roughly 10% of the peak load. The result is
a grid system that meets U.S. electricity demand dependably
in all regions, even during periods of high demand and/or low
renewable energy generation. The case was tested using the
PLEXOS production cost model run hourly for seven historical
weather years, testing the grid system using actual weather
data, to show that the system could meet the projected load with
expected solar and wind production.
Previous studies, such as NREL's Renewable Electricity
Futures from 2011, demonstrated the feasibility of operating
the grid on higher percentages of weather-dependent
resources. The costs for these scenarios, however, were projected
to be much higher than the results from our study. In the
2035 study, wholesale electricity costs are 13% lower in 2035
under the 90% Clean case than they are in 2020, thanks to the
dramatic decline in solar photovoltaic (PV), wind, and storage
1,000
2,000
3,000
4,000
5,000
Solar
Wind
Hydro
Nuclear
Geothermal
Biopower
Other
Gas
Coal
2020
2025
(a)
figure 1. Generation in the (a) 90% Clean and (b) No New Policy cases.
68
ieee power & energy magazine
november/december 2021
2030
2035
1,000
2,000
3,000
4,000
5,000
2020
2025
(b)
2030
2035
Solar
Wind
Nuclear
Other
Gas
Coal
Hydro Geothermal
Biopower
Annual Generation (TWh/year)
Annual Generation (TWh/year)
IEEE Power & Energy Magazine - November/December 2021

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