Mandating lower minimum operating levels for coal plants increases power system costs across most green energy adoption levels in India. Engineers expected that throttling coal generators down would ease renewable energy integration and save money. Instead, running coal boilers at low capacity burns coal less efficiently and parks heavy generators on the grid, shutting out solar and wind power.
When a coal plant reduces its minimum operating level to 40 percent of capacity, boiler combustion loses thermal efficiency and consumes extra fuel per unit of electricity generated. The throttled coal stations stay connected to the electrical grid like idling trucks clogging a delivery lane. Because these thermal generators occupy grid capacity, grid controllers must disconnect solar panels and wind turbines from power lines. This forced curtailment wastes zero-emission electricity while the grid continues to pay for inefficient coal burning.
Researchers evaluated this policy by simulating 125 power plants at 15-minute intervals across 21 operating scenarios. They found that cost savings occur only within a narrow renewable penetration window between 6 and 12.5 percent. At India’s projected 2030 renewable trajectory of roughly 22 percent, national fleet costs rise by 521 million to 1.09 billion dollars annually while discarding up to 1886 gigawatt-hours of clean power.
Grid planners can avoid fleet-wide thermal flexibility mandates that yield diminishing or negative economic returns during deep decarbonization. Rapid renewable growth carries the power system past the brief savings window within one to two years, leaving thermal plant retrofits unrecovered.