South Carolina’s Bad Creek could gain a second underground powerhouse with four reversible turbines, without building new reservoirs

South Carolina plans to expand its long-duration storage capacity that will feature reversible turbines.

The state is experiencing significant population growth and rapid economic development.

As these expansions continue, the pressure on regional power infrastructure and energy supplies intensifies.

Industrial operations are rising due to tech expansions, heavy industrial manufacturing, and electric vehicle battery facilities.

To address these challenges sustainably, state leaders are increasingly relying on proven, utility-scale storage assets.

Will the proposed expansion at an existing hydro plant help relieve grid strain and meet surging power demands?

How South Carolina’s electricity consumption is suddenly surging

The unprecedented influx of new residents to South Carolina, along with rapid industrialization, is driving major power demand.

Newcomers are attracted by major corporate investments and strong job growth.

This has pushed annual statewide retail power sales over 83.9 million megawatt-hours.

Industrial operations are rising due to tech expansions, heavy industrial manufacturing, and electric vehicle battery facilities.

These operations account for nearly 28% of South Carolina’s total electricity consumption.

Altogether, regional energy demand is driven to record levels.

Utilities now supply electricity to 2.9 million customers across the Carolinas, with almost 860,000 located in South Carolina.

Grid capacity is further strained by intense power surges created by residential cooling demand during summer heatwaves.

Operators are now tasked with managing surging loads while maintaining overall system reliability as sustainably as possible.

This requires large-scale renewable energy generation and storage capacity.

Without it, South Carolina will struggle to meet statutory climate targets.

Meeting clean energy goals while addressing intermittency

State policy and regional utilities encourage expanding reliance on renewable energy assets.

This is key to maintaining long-term grid stability while combating rising emissions.

Duke Energy, which serves a vast portion of South Carolina, is operating under corporate and regional commitments. This is to achieve net-zero targets by 2050.

The integration of solar and wind power into the state’s energy mix has helped progress the state’s green shift.

However, these sources present major operational bottlenecks.

Both are inherently intermittent, with output dropping just as peak residential electricity usage surges.

To overcome this, the deployment of standard battery energy storage systems is being encouraged.

Unfortunately, they offer short-term relief, dispatching power for only two to four hours.

They also experience continuous efficiency degradation over repeated cycles.

That is why developers are increasingly turning to hydroelectric pumped storage, which offers superior long-duration storage.

A recently proposed major project is now under review by the Federal Register – Duke Energy.

Bad Creek II’s reversible turbines and other pumped storage infrastructure

Duke Energy has proposed a second underground Bad Creek powerhouse.

The existing project is located in Oconee County, South Carolina, adjacent to Lake Jocassee.

It has been operating since 1991, and recent upgrades raised the facility’s total generating capacity to 1,680 megawatts.

It uses a 363-acre upper reservoir and underground powerhouse with four reversible pump-generating turbines.

A new 50-year operating license renewal has been submitted ahead of the current license expiration in July 2027.

The Bad Creek II Complex has been proposed to support unprecedented regional demand growth.

The details of the newly proposed project

A new underground powerhouse with four reversible pump-turbines will be built.

It will provide between 106 and 425 megawatts of additional capacity.

The new complex will require:

• A new upper reservoir intake structure
• A lower reservoir inlet/outlet structure
• Underground conveyance tunnels
• A switchyard and transformer yard
• Transmission lines

The infrastructure will boost site capacity without having to change the existing upper or lower reservoirs.

FERC has formally accepted the relicensing application for filing, which is now ready for environmental analysis.

Once the second complex is approved and operational, it will store excess off-peak clean energy. On-demand clean energy will then be supplied during peak hours.

Ultimately, expanding hydroelectric pumped storage facilities is key to stabilizing regional power grids.