As Duke Energy Corp.'s fleet of coal generation shrinks in the Carolinas, the company will largely rely on the addition of natural gas plants complemented by renewables to meet growing customer demand and offset planned retirements.
Duke Energy subsidiaries Duke Energy Carolinas LLC, or DEC, and Duke Energy Progress LLC, or DEP, filed their integrated resource plans Sept. 5 with the North Carolina Utilities Commission. The utilities file separate integrated resource plans, or IRPs, for North Carolina and South Carolina, but each plan analyzes the system as one utility across both states. The plans cover the period from 2019 to 2033.
DEC said it plans to reduce dependence on coal-fired generation over the next 15 years with installed coal capacity dropping to 18% of the company's total portfolio by 2033 from 29% in 2019.
The utility plans to retire all five units at the 1,161-MW G.G. Allen coal plant by December 2028. The IRP also assumes the retirement of the 546-MW unit 5 at the Cliffside coal plant in December 2032.
To offset the loss of coal capacity, DEC's 2018 IRP calls for an 8% increase in natural gas generation and 8% growth in renewable resources, energy efficiency and demand-side management. Based on this assumption, natural gas will make up 54% of the planned resource additions over the planning period, accounting for 32% of the capacity mix by 2033. Renewables and energy efficiency programs represent 40% of the additional resources and account for 16% of the 2033 capacity mix.
DEC's resource plan calls for about 3,600 MW of combustion turbine and combined-cycle natural gas generation as part of its need for approximately 4,059 MW of new resources. This includes the addition of 1,338 MW of combined-cycle capacity in both December 2027 and December 2030 along with the addition of 460 MW of combustion turbine capacity online in December 2032.
Also, a new 402-MW unit at the Lincoln Combustion plant is expected online in December 2024. The IRP assumes the retirement of the 173-MW W.S. Lee gas plant in December 2030.
The 16-MW Clemson University Combined Heat and Power facility is expected to begin operations in November 2020. The IRP includes an additional 22 MW of combined heat and power capacity in both 2020 and 2021.
DEC also includes a placeholder for 150 MW of "grid-connected battery storage" and plans to complete capacity uprates at its 1,360-MW Bad Creek Pumped Storage Project in South Carolina between 2020 and 2024.
DEP projects the need for about 6,300 MW of new resources over the 15-year planning horizon.
The utility forecasts natural gas generation will constitute about 77% of its resource additions over the period, growing to 51% of the capacity mix by 2033 from 33% in 2019. Over the same period, coal capacity will shrink to 9% from 19% of the total portfolio.
Renewables and energy efficiency programs represent 21% of the additional resources and account for 22% of the 2033 capacity mix.
DEP will retire the 384-MW Asheville coal plant in November 2019 and replace it with the 560-MW Asheville combined-cycle gas plant as part of its more than $1 billion Western Carolinas Modernization Project.
The utility's resource plan also calls for the retirement of the first two units at its Roxboro coal plant, representing 1,053 MW of capacity, in December 2028.
Other planned retirements in DEP's resource plan include units 1 to 4, 6 to 8, and 10 at the Darlington County gas plant in South Carolina, representing 514 MW of capacity, by December 2020; the 68-MW Blewett combustion turbine fuel oil plant in December 2024; and the 164-MW W.H. Weatherspoon combustion turbine fuel oil plant in December 2024. DEP has already retired units 5 and 9 at the Darlington gas plant.
The IRP also calls for the addition of 1,338 MW of combined-cycle capacity online in December 2024 and December 2026. DEP forecasts 1,840 MW of combustion turbine capacity online in December 2028 followed by 460 MW of combustion turbine capacity online in December 2031 and December 2032.
Outside of a heavy reliance on natural gas, both DEC and DEP plan to boost their clean energy portfolios.
DEP's 2018 plan calls for installed solar capacity to grow to 4,199 MW in 2033 from 2,758 MW in 2019.
DECs resource plan assumes the utility's installed solar capacity increases to 3,440 MW in 2033 from 1,218 MW in 2019.
Both utilities must issue requests for bids to procure 2,660 MW of new renewable energy resources within the next five years under a 2017 North Carolina law.
No new nukes
No nuclear generation is added to either utility's system over the planning period. Nuclear capacity drops to 21% of DEC's capacity mix by 2033 from 25% in 2019 and falls to 16% of DEP's 2033 capacity mix from 19% in 2019.
"Low natural gas prices, the absence of national carbon regulation and other industry factors have collectively moved the need for new nuclear generation outside the current planning window," DEC wrote in its resource plan.
After scrapping plans to build the 2,234-MW William States Lee III Nuclear Station in South Carolina, Duke Energy has indicated it will focus on license extensions instead of nuclear development.