The Hindu BusinessLine•
Why, at 42.79%, record RE penetration is as much a cause for worry as cheer
At 12:29 hours on July 13, India achieved a record that went almost unnoticed. Wind and solar together accounted for 42.79 per cent of the electricity being generated in the country at that instant — the highest ever share of variable renewable energy (VRE) in the grid.
Wind and solar together were generating electricity at a rate of 103.7 GW, another record. (GW measures the rate at which energy is generated, much like the horsepower rating of a water pump indicates how much water it can move at any instant.)
Wind and solar had touched their individual milestones earlier. Wind’s share in generation reached a record 17.13 per cent on July 12, while solar’s highest penetration was 39.1 per cent on March 3.
The record renewable energy penetration on July 13, even if for a short duration, illustrates how far India has come in clean energy. Today, VRE capacity (wind plus solar), at 219.6 GW, accounts for 40 per cent of the total installed power capacity of 548.85 GW.
The high penetration of VRE is indeed a cause for celebration; equally, it is a warning to grid operators. VRE is good news for energy decarbonisation, but a headache for grid operators. If the output from wind and solar suddenly falls because the wind has dropped or clouds have rolled in, then another source — typically coal, hydro or storage — must step in almost immediately. Electricity generation and demand must be balanced every second, otherwise the grid itself comes under stress.
The obvious answer is ‘storage’. Batteries can absorb surplus solar electricity during the afternoon and feed it into the grid after sunset, when demand is high and solar generation stops. Recognising this need, India has begun awarding large battery energy storage projects. But storage alone cannot carry the burden. An oversized battery capacity built for storing the maximum generation is economically unwise.
That is why coal, ironically, has become an important enabler of renewable energy. India’s coal stations were designed to run steadily as baseload generators. The Central Electricity Authority (CEA) has laid down a roadmap for making coal plants more flexible, ultimately enabling many units to tune down, within minutes, their operations to as low as 40 per cent of their rated capacity. In practice, however, much of the fleet remains stuck at a minimum operating level of around 55 per cent. Running plants at lower loads reduces efficiency, increases wear and tear, and raises maintenance costs, which the generators are loath to bear.
A renewable-rich grid, however, demands flexibility. The engineering solutions are largely known. The need of the hour are market instruments that help pay for flexibility. Today’s electricity market largely rewards generators for the number of units they produce. Tomorrow’s grid will increasingly need mechanisms that reward flexibility and reliability.
Capacity markets — a concept that’s just being introduced in India — compensate generators or storage providers for being available when the system needs them, even if only occasionally. They reward the ability to provide firm power whenever required. Such market instruments recognise that, in a renewable-rich grid, availability can be as valuable as generation itself.
Former GRID-INDIA chairman SR Narasimhan, commenting on the July 13 milestone, has argued that higher renewable penetration must be accompanied by greater grid discipline.
GRID-INDIA has petitioned the Central Electricity Regulatory Commission (CERC) for powers to disconnect renewable generators that repeatedly fail to comply with grid regulations. Renewable generators are mandated to equip their plants with low-voltage and high-voltage ride-through (LVRT and HVRT) capability — tools that strengthen grid resilience by enabling the generators to remain connected and support the grid during temporary voltage disturbances, instead of disconnecting and worsening the problem. The commission is yet to grant the permission — perhaps because there is a pushback from the generators.
Narasimhan also urges the CEA to announce the “long-overdue” fresh (revamped) Technical Standards for Connectivity to the Grid Regulations.
Why, at 42.79%, record RE penetration is as much a cause for worry as cheerRead More →