NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Research Findings for the Electricity Sector of the USA, the West, and California Trieu Mai, Ph.D. California Energy Commission IEPR Workshop Sacramento, CA July 24, 2015

2 Outline NREL modeling capabilities Summary findings from 3 studies 1.Renewable Electricity Futures Study (REFS) 2.Western Wind and Solar Integration Studies (WWSIS) 3.Low Carbon Grid Study (LCGS)

3 Models developed or run at NREL Regional Energy Deployment System (ReEDS) model – long-term (2050) national capacity expansion Resource Planning Model (RPM) – regional year IRP-type planning tool PLEXOS – commercial production cost model (developed by Energy Exemplar)

4 Renewable Electricity Futures Study RE generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050—while meeting electricity demand on an hourly basis in every region of the country.

5 REFS: All regions of the country could contribute substantial renewable electricity supply in % RE-ITI scenario

6 REFS: Incremental cost associated with high RE generation is comparable to published cost estimates of other clean energy scenarios 80% RE scenarios are estimated to have similar incremental cost compared with EIA and EPA scenarios that have similar levels of carbon emission reductions (75-80%) With updated technology costs, fossil fuel price projections, and retirements, incremental costs for 80% RE are estimated to be lower 2014 updated scenarios

7 Western Wind and Solar Integration Study Phase 1 – Can we integrate high penetrations of wind and solar (e.g. 35%) into the Western Interconnection? Phase 2 – What is the impact of 33% wind and solar on the fossil fuel plant cycling and emissions? Phase 3 – How do high penetrations of inverter-based generation resources like wind and PV solar affect system reliability in the first minute after a large disturbance?

8 WWSIS-2: Focus on fossil-fuel unit cycling

9 WWSIS-2: Emissions impacts of cycling are relatively small

10 WWSIS-3: Frequency Response Disturbance: Trip 2 Palo Verde units (~2,750MW) 3 2 Light Spring Base Light Spring High Mix Light Spring Extreme Even at extreme levels of wind and solar, performance meets criteria - Interconnection frequency response > 840 MW/0.1Hz threshold in all cases. No under-frequency load shedding (UFLS). With good system planning, sound engineering practices, and commercially available technologies, the Western Interconnection can withstand the crucial first minute after grid disturbances with high penetrations of wind and solar on the grid.

11 Low Carbon Grid Study for California The California 2030 Low Carbon Grid Study is a modeling effort that explores the ability of California’s electricity system to cost-effectively support deep emissions reductions by the year Phase 1 – study results available on website Phase 2 – ongoing, to be published soon California’s electric sector can cut its carbon footprint in half by 2030 with minimal rate impact, minimal curtailment of renewable energy, and without compromising reliability.

12 LCGS: Renewable portfolios in each case Load: 341 TWh RE: 125 TWh CEC “Mid” EE 1.5 GW new storage Load: 321 TWh RE: 179 TWh CEC “High Mid” EE 3.5 GW new storage Baseline Case is similar to LTPP % Case Has higher penetration of rooftop PV (24 TWh in LCGS compared to 7.7 TWh in LTPP) Higher overall load (and higher PV penetration to make up RPS energy short) Target Case Many variants modeled with different RE portfolios and system flexibility

13 LCGS: Significant California CO2 emissions reductions for all “Target” (55% RE) cases Total 2013 CA emissions = 459 MMT 2013 CA electricity sector emissions (in-state generation + imports) = 91 MMT

14 LCGS: Most target scenarios are estimated to yield >$4 billion in annual production cost savings Total production cost assigned to CA = $12.7B in the Baseline Capital cost impacts analysis (JBS Energy, Inc.) will be included in final study report

15 LCGS: The amount of renewable curtailment is most sensitive to system flexibility Marginal curtailment rates can be higher

16 ReEDS: RPM: Mai et al. (2015). Implications of Model Structure and Detail for Utility Planning: Scenario Case Studies Using the Resource Planning Model - PLEXOS: o Demand Response: Hummon et al. (2014). Grid Integration of Aggregated Demand Response… - o Storage: Denholm et al. (2013). The Value of Energy Storage for Grid Applications - o Eastern Renewable Grid Integration Study (ERGIS) - o High Performance Computing: Barrows et al. (2014). Time Domain Partitioning of Electricity Production Cost Simulations - Additional References Thank you.