Which combination is most effective for balancing supply and demand in a high-renewables grid?

• A. Relying solely on transmission expansion without storage.
• B. Building more coal plants.
• C. Demand response along with energy storage that has high round-trip efficiency.
• D. Ignoring demand signals and accepting variability.

Answer: (C)

In a high-renewables grid, the main challenge is aligning when power is available with when it’s needed, since wind and sun can’t be counted on to match demand every hour. You want flexibility both on the supply side and the demand side. Demand response lets consumers shift or reduce their usage in response to grid needs, cutting peak demand and smoothing the overall load. Energy storage with high round-trip efficiency stores surplus generation when renewables are plentiful and releases it when generation dips, minimizing losses and keeping the system reliable without needing extra fossil-fuel generation. Put together, these tools address timing mismatches and support higher renewable penetration.

Relying only on transmission expansion helps move electricity around but doesn’t solve the timing gap between when electricity is produced and when it’s needed. Building more coal plants adds generation but is inflexible, slower to ramp, and undermines emissions and renewable integration goals. Ignoring demand signals guarantees persistent mismatches between supply and demand.