How a federal standard for clean energy could shape the generation landscape in the southeastern United States is examined in a new report by the Southern Alliance for Clean Energy entitled “Achieving 100% Clean Electricity in the Southeast”.
The report looks at various scenarios the region's three major utilities (NextEra, Duke Energy, and Southern Company) as well as the Tennessee Valley Authority (TVA) could undertake to achieve 100 percent renewable generation under a federal mandate.
The study assumes that any federal clean energy standard (CES) would require TVA to achieve 100% clean electricity by 2030, and the other utilities must follow suit by 2035. The report is also not a lowest cost optimization and does not take into account most of the transmission or distribution constraints.
The report also only takes into account existing non-carbon-emitting technologies without speculating about future technological improvements; it said these future technologies would only make reaching a CES easier.
Customer-oriented DERs
The first of the two paths considered focuses on customer-owned decentralized energy resources (DER), which would play a major role in the energy transition.
According to the report, this way TVA can achieve 100% clean energy with a capacity mix of 10% decentralized solar and energy efficiency measures, 41% large-scale solar energy, 17% wind, 8% other renewable resources and 12% existing nuclear power plants capacity and 13% energy storage.
Within the scenario, the storage is used to cover the winter reserve margins and is not fully used even on peak days. This means that the proposed amount of storage for TVA is available “just in case” of equipment failure or outages during peak events.
Inside Georgia Power's Vogtle Unit 4 nuclear containment building.
Image: Georgia Power
Southern Company's energy mix is divided among its three utilities: Alabama Power, Georgia Power, and Mississippi Power. These utilities currently rely on fossil fuels, particularly Mississippi Power, which is currently expected to have 90% of its generation mix made up of fossil fuels by 2035. The customer-centric path would change the mix of any utility company:
- Alabama Power: 12% decentralized solar and energy efficiency measures, 37% solar, 21% wind, 7% other renewable energies, 7% existing nuclear energy capacity and 16% energy storage;
- Georgia Power: 16% distributed solar and energy efficiency measures, 38% solar, 16% wind, 5% other renewables, 8% existing nuclear capacity and 17% energy storage;
- Mississippi Power: 7% decentralized solar and energy efficiency measures, 42% solar energy, 34% wind energy, 3% other renewable energies, 0% existing nuclear energy capacity and 14% energy storage.
For these utilities, resource capacity needs are determined by the form of demand in winter, although there is relatively little surplus generation during peak summer days. The renewables and storage to cover summer and winter peaks are expected to be sufficient to meet the load on a typical spring day, which means that utilities could likely operate some or all of the nuclear capacity in winter and summer only.
Solar at Daytona Motor Speedway in Florida.
Image: Florida Power & Light
The NextEra plan includes the utility's plan to integrate Gulf Power into Florida Power and Light by 2022. The resources required for this scenario are driven by the winter peak, which is due to the lower solar production in winter.
The proposed energy mix includes 15% decentralized solar and energy efficiency measures, 51% solar energy, 9% wind power, 2% other renewable energies, 6% existing nuclear energy capacities and 17% energy storage.
This scenario also makes NextEra's power grid less reliant on imports of fuel from outside the state due to the proposed penetration of solar and storage.
And similar to Southern Company, Duke Energy's mix is split across its three utilities: Duke Energy Carolinas, Duke Energy Progress, and Duke Energy Florida. The scenarios for Duke Energy Carolinas and Duke Energy Progress differ from Duke Energy Florida in that the Sunshine State utility has no nuclear power capacity and does not build onshore wind power on its territory. The scenario looks like this:
- Duke Energy Carolinas: 12% decentralized solar and energy efficiency measures, 46% solar, 17% wind, 4% other renewable energies, 10% existing nuclear energy capacity and 11% energy storage;
- Duke Energy Progress: 8% decentralized solar and energy efficiency measures, 51% solar, 15% wind, 3% other renewable energies, 7% existing nuclear energy capacity and 17% energy storage;
- Duke Energy Florida: 9% decentralized solar and energy efficiency measures, 55% solar, 6% wind, 3% other renewable energies, 0% existing nuclear energy capacity and 27% energy storage.
Since Duke Energy Florida has little wind and no nuclear power, solar power and storage play a bigger role here than in any other scenario studied.
Phipps Bend solar farm in Tennessee, built by United Renewable Energy, near an abandoned TVA nuclear project.
Image: United Renewable Energies
All of these scenarios are based on some key mindset changes for the region, including an immediate and significant commitment to energy efficiency, demand response and decentralized solar from 2022, increased investment in utility-scale solar and storage expansions, and some reliance on local wind, which historically was considered with low feasibility.
Great dependence on renewable energies
The second important path is more based on the expansion of large capacities through large-scale renewable energies and assumes that the DER penetration levels are lower than the DER-focused CES paths, but still higher than the current supply plans.
In this second way, TVA can achieve 100% clean energy with a capacity mix of 9% decentralized solar and energy efficiency measures, 38% large-scale solar energy, 22% wind, 8% other renewable resources, 12% existing nuclear energy capacity and 12% energy storage.
Norris hydroelectric power station. TVA's existing water and nuclear power resources are helping to achieve 100% clean electricity by 2030.
Image: Tennessee Valley Authority
TVA's existing hydropower and nuclear resources are helping to achieve 100% clean electricity by 2030, even with lower DER penetration, although it is only 1% lower and TVA has not historically been the most widely distributed solar friendly. The case would also require nearly doubling the wind developed within the TVA service area.
As for the three subsidiaries of the Southern Company, their large-scale blends put major capacity on the shoulders of solar and wind power while still maintaining significant DER penetration. This is how it works:
- Alabama Power: 11% decentralized solar and energy efficiency measures, 32% solar energy, 28% wind energy, 7% other renewable energies, 7% existing nuclear energy capacity and 15% energy storage;
- Georgia Power: 15% distributed solar and energy efficiency measures, 39% solar energy, 19% wind energy, 5% other renewables, 7% existing nuclear energy capacity and 16% energy storage;
- Mississippi Power: 7% decentralized solar and energy efficiency measures, 38% solar, 42% wind, 2% other renewable energies, 0% existing nuclear energy capacity and 11% energy storage.
110 MW tracker installed in Alabama
Image: NEXTracker
Alabama Power has the largest increase in wind and has almost no excess generation on its peak summer day, meaning that on this large-scale, renewable-energy path, both winter and summer peaks are increasing the demand for resources. Georgia Power sees a very similar surplus situation and Mississippi Power relies heavily on wind and sun in this scenario.
With NextEra, the large-scale, renewable energy-oriented path is again heavily focused on solar and storage. The energy mix of the energy supplier would therefore look like 13% decentralized solar and energy efficiency measures, 48% large-scale solar energy, 17% wind, 2% other renewable resources, 6% existing nuclear energy capacities and 14% energy storage.
Finally, as part of this large-scale, renewable-energy pathway, Duke's utilities are also turning heavily into solar and storage technology, particularly Duke Energy Florida. Here is the breakdown:
- Duke Energy Carolinas: 11% decentralized solar and energy efficiency measures, 47% solar, 19% wind, 2% other renewable energies, 9% existing nuclear energy capacity and 12% energy storage;
- Duke Energy Progress: 7% decentralized solar and energy efficiency measures, 52% solar, 17% wind, 1% other renewable energies, 6% existing nuclear capacity and 17% energy storage;
- Duke Energy Florida: 8% decentralized solar and energy efficiency measures, 53% solar, 11% wind, 1% other renewable energies, 0% existing nuclear capacity and 26% energy storage.
Despite less emphasis, DERs still play a fundamental role in achieving 100% clean electricity with a focus on large renewable resources across all utilities and subsidiaries analyzed in the report, as any reduction in load or spikes from DERs reduces the need for the construction of large renewable energies. The report's authors strongly believed that an aggressive and sustainable investment in DERs is important on any journey to 100% clean electricity.
The scenarios outlined under the second path are also based on putting many large projects online quickly, which means that location and approval procedures must be streamlined as much as possible while remaining environmentally friendly.
The report outlines some alternative strategies, but the purpose of the publication was to highlight that the region can get 100% clean electricity with technologies available today. However, investments in research and development of new technologies should not be overlooked.
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