IEEE Power & Energy Magazine - July/August 2015 - 49

Overgeneration (MW)

CO2 prices from US$10
30,000
to US$100/metric ton,
50% Large Solar
and a range of solar PV
Enhanced Regional Coordination
and wind costs), the
25,000
higher renewable sceConventional Demand Response
narios result in higher
Flexible Load/Energy Storage
20,000
electric rates. The rate
Diverse Renewable Portfolio
impacts are expected
15,000
to be lowest under the
high gas and CO2 price
10,000
sensitivity with low renewable energy costs.
✔✔ Rate increases are ex5,000
5,000 MW
pected to be significantly higher under the
0
0%
5%
10%
15%
20%
25%
30%
50% scenarios than
% of Hours
under the 40% scenario. This is primarily
figure 5. Renewable integration solutions such as enhanced regional coordination, flexible
due to the exponential loads, energy storage, and procuring a diverse portfolio of renewable resources can signifiincrease in renewable cantly reduce renewable overgeneration.
energy curtailment as
the renewable target increases toward 50%, requiring a
these sensitivity results are reduced when PV costs are
significant "overbuild" of the renewable portfolio to meet
lower than in the base case.
the standard.
✔✔ The small solar and rooftop scenarios are costlier
than the large solar and diverse scenarios. This is
✔✔ The diverse scenario shows a substantially lower rate
largely due to the difference in cost and performance
impact than the more heavily solar dominated cases,
assumed for distributed PV systems relative to cenprimarily because the diverse portfolio results in less
tral station systems. Rooftop systems, in -particular,
overgeneration. This is despite the fact that the "first
are significantly more expensive than larger systems
cost" of the resources-the cost of a renewable power
and have lower capacity factors (due to suboptimal
purchase agreement-is higher in this scenario than
tilt and orientation as well as location in coastal arin the large solar scenario. This higher first cost is
eas). Differences in transmission and distribution
more than made up for by the r- educed curtailment that
costs are small.
occurs due to a more diverse output profile.
The projected cost increases for the higher renewable
✔✔ The rank order on costs between the scenarios stays
the same under all uncertainty ranges considered. scenarios are due largely to the high and increasing cost
Costs are expected to be highest under the rooftop so- of renewable integration. While wind and solar costs are
lar scenario, followed by the small solar, large solar projected to be comparable to the cost of conventional
and diverse scenarios. The cost differences between resources on a levelized cost of energy basis in 2030,

table 4. 2030 revenue requirement (in 2012 US$ billion) for each scenario,
percentage change is relative to the 33% scenario.
50% RPS
Diverse

50% RPS
Small Solar

50% RPS
Rooftop
Solar

Revenue Requirement Category

33% RPS

40% RPS

50% RPS
Large Solar

CO2 compliance cost

3.2

2.9

2.5

2.4

2.5

Conventional generation

20.3

19.5

18.7

18.1

18.7

18.6

Renewable generation

8.2

10.6

17.1

14.8

18.5

22.8

Transmission

6.5

7.1

7.8

7.9

7.4

7.3

Distribution

16.2

16.3

16.7

16.5

Miscellaneous/other costs

2.5

Total

56.9

58.8

64.9

62.1

66.3

70.3

Percentage change

n/a

3.2%

14%

9.1%

16.4%

23.4%

july/august 2015

ieee power & energy magazine

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - July/August 2015