IEEE Power & Energy Magazine - July/August 2018 - 63

in California, curtailment increases from less than 1% of
annual Vre generation in the 2030 reference case to less than
4% of annual Vre generation in the high-electrification scenario, even with over 60% of electricity sales coming from
renewable resources. the electrification of buildings in California has little effect on renewable curtailment through 2030
because electric loads from space heating and water heating
largely occur during the mornings, evenings, and in the winter, when solar generation is less plentiful. in our analysis,

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California's electric generation mix is currently about 50%
natural gas including imports and combined heat and power,
40% zero-carbon renewable generation [including utilityscale renewables, rooftop solar photovoltaic (PV) systems,
and hydroelectric generation], with the remainder coming
from nuclear generation and out-of-state coal. By 2030, in
the high-electrification scenario, gas generation is cut in half,
falling to less than 25% of total generation. Coal imports
disappear while zero-carbon generation resources represent
over 70% of the generation mix in 2030. By 2050, the generation mix is 95% zero carbon (figure 4).
the renewable capacity build-out required to achieve these
levels of zero-carbon generation is impressive, nearly tripling in
fewer than 15 years. in the high-electrification scenario, utilityscale solar PVs increase from fewer than 10 gW today to more
than 30 gW in 2030, accompanied by an expansion in rooftop
solar PVs from 5 gW today to 18 gW by 2030. in-state wind
resources stay relatively constant between 8 and 9 gW through
2030, while out-of-state wind development is only assumed
to occur after 2030 due to challenges with building interstate
transmission lines to deliver the wind to loads.

Curtailment

2015

Electric Generation

which could result in either higher or lower peak demand
impacts, depending on the timing of the vehicle charging.

Generation (TWh)

sectors of the economy that are otherwise difficult to electrify, such as heavy-duty trucks and some industrial applications. in the high-electrification scenario, new electric loads
from hydrogen production represent 2% of total electricity
loads in 2030, growing to 10% of total electric demand by
2050. similar dynamics could occur in the northeast, though
that study did not explore hydrogen pathways.

Imports Hydro
Rooftop PV Wind

Peak Demand and Capacity Needs

july/august 2018

figure 4. California electricity generation mix and percent
zero-carbon electricity in the high-electrification scenario
(2015-2050).

System Peak Demand (GW)

in the high-electrification scenario, the 2030 system peak
demand is only slightly higher than today's level and actually lower in 2030 compared to the reference scenario, due to
high levels of ee and flexible loads. By 2050, even with total
electricity loads doubled, the system peak demand is barely
higher than in the reference scenario due to the aggressive
implementation of energy efficiency, controlled eV charging, and flexible loads in buildings. Without the benefit of
higher ee (reference efficiency) or flexible loads in buildings or controlled charging of eVs (no flexible loads), system peak demands in the high-electrification scenario could
be 10-20% higher than in the reference scenario by 2050
(figure 5). California's new renewable and energy-storage capacity, in combination with existing levels of gas and
hydroelectric capacity, is expected to be sufficient to meet
the state's 2030 planning reserve margin, although more
detailed studies are needed.
this finding emphasizes the importance of flexible building loads and controlled eV charging for managing future
system peak demands. these scenarios assume widespread
adoption of lower voltage (240 V) eV charging during daytime periods. none of the scenarios evaluated the impact of
dc fast charging (480 V) of eVs on system peak demand,

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Reference
High-Electrification Scenario
High-Electrification Scenario
with Reference Efficiency
High-Electrification Scenario
with No Flexible Loads

figure 5. California system peak demand by scenario (in
gigawatts, net of behind-the-meter generation).
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Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2018