Flexible Power Generation
India’s NEP has set the new target of 40% of total electricity from RE by 2030 and the country has already added 71.85 GW of RE by October 2018. As per NEP, by March 2019, India’s thermal power capacity will shrink down to 63% from 70% of total installed capacity of about 350 GW.
India’s large coal-based installed capacity of approximately 193 GW accounts for 58% of the country’s total installed capacity. There is a growing need for flexible operations in the coal fleet to meet the variations and intermittence of VRE capacity, primarily wind and solar, into the grid. The NREL grid integration study under GTG establishes that the Indian power grid shall be able to integrate large-scale VRE with minimal curtailment provided the balancing sources like coal are available to support grid stability. A 2016 POSOCO study also identified the need for flexible operations in India.
During high VRE penetration, the coal-based plants shall be required to run at minimal loads (technical minimum) and should be able to quickly ramp up/down as per the variations in VRE resources to address grid stability. Presently, this flexible generation of coal-based plants in India is mandated at a minimum of 55% for interstate generating plants. In the near future, with increased VRE penetration, operators shall be required to run their plants at further reduced loads. Existing plant configurations, firing systems, controls and instrumentation impose legitimate constraints on ramp rates and technical minimums. The GTG-RISE pilot will examine to what extent retrofits/upgrades and operating practice changes are required in the Indian coal-based plants to improve ramp rates and achieve lower technical minimums.
Pilot Scope & Outcome
The flexibility pilots are helping India build a strategy to address the variability in RE generation, and set a benchmark for the entire South Asia region.
GTG-RISE is supporting technical interventions and operational changes at NTPC’s Ramagundam (200 MW unit), Jhajjar (500 MW unit) and GSECL Ukai TPS (200MW & 500 MW unit). The pilot will examine the possibility of faster ramp rates and lower technical minimums in two coal-based power generating units one each at NTPC Ltd and Gujarat State Electricity Corporation Limited (GSECL). It will also support implementation of the recommended measures by NTPC and GSECL for achieving the flexible operations of the units. The pilot will suggest potential modifications to the generating units, identify operating practice changes, and build the business case for policy and regulatory changes to implement coal flexing at a larger scale. NTPC and GSECL stations shall benefit by adapting recommendations that would be replicable for their similar range of coal fleet units.
Stage 1: Techno Economic Assessment & Roadmap
- Technical due diligence and detailed feasibility assessment
- Establishing reliable costs of flexibilisation – capex as well as opex
Stage 2: Regulatory Pathway and Fleet Level Strategies
- Assistance in framing Regulatory Mechanisms for Flexibility.
- Assistance in building fleet level strategies for NTPC / GSECL
Stage 3: Pilot Implementation
- Technical Assistance in pilot / fleet level implementation to NTPC
- Leverage private partnerships and contribution in investments
Stage 4: Scale up
- Assist in fleet-wide implementation and national scale up
- Capacity building of operators – Procedures and Operational Toolkits
“GTG-RISE pilot studies suggest India can make 60-80 GW of its coal power plants more flexible with approximately $2 billion of investment.”
GTG-RISE team, in technical assistance from Intertek AIM, USA, has already completed the damage cost modelling studies conducted at the NTPC’s Ramagundam (200 MW), Jhajjar (500 MW) and GSECL’s Ukai TPS (200MW & 500 MW) and key recommendations from the draft feasibility reports have been shared with NTPC and GSECL
Key Recommendations & Takeaways
- Modification of Operation Practices
- Carry out test runs to determine system limitation and determine the minimum load possible
- Consider nitrogen cap on the open condensate tanks.
- Ensure dampers are automated and fully functioning
- Installation of Modified programmable flame scanners
- Multiple fill cycles for the boiler feed water to the drum
- Review soot blowing schedule for optimized cleaning (auto sensors – Boss)
- Online burner tuning, with a flame mapping system should be considered.
- Hangar indication markers for hot/cold
- Minimize Air In-Leakage.
- Primary Air – APH, consider replacing the swing arm with traveling sootblower and use dry SH steam
- Utilizing the steam coils at low loads for the APH
- Reducing the number of mills in operation
- Installation of Asset health monitoring equipment
- Avoid manual override during start-ups
- Automation of drain valves
NTPC has already moved ahead, with one of the suggested recommendation on, retrofitting of Nitrogen Sparging and blanketing system in demineralised (DM) storage and condensate storage tanks across its NTPC stations.
In addition, the GTG-RISE coal flexibility experts also supported to guide the successful pilot test run at NTPC’s Mauda Unit in Maharashtra (February 15 – 17, 2019) and will help in determining the system limitations for flexible operation and lowering the stable minimum load level .The test run will be helpful in preparing standardizing operational procedures for flexible operation.
Recently, Gujarat made its first successful move to achieve greater load flexibility at its coal-based plant to boost integration of renewables. With support from USAID, Gujarat’s state power generation utility successfully operated its 500 MW Ukai unit at only 40 per cent (200 MW) of its capacity during a recently conducted low load test run. This is the first time that the Gujarat State Electricity Corporation Limited (GSECL) has been able to run its Unit to the lowest possible load points while still maintaining all the other operating parameters under stable conditions and without any supplementary oil firing support. These test run results will enable GSECL to further optimize its operating costs and customize its load under future flexible operating conditions. The low load test run was conducted with support of GTG –RISE initiative and Bharat Heavy Electricals Limited (BHEL), which is the Original Equipment Manufacturer. Every coal-plant has its own vintage, plant specifications and operational characteristics and to lower the plant load it requires a detailed procedure with the list of actions that should be taken in the event of faults or potential dangers. The test runs carried out at Ukai unit followed the low load/ramp procedures developed by GTG-RISE & BHEL, which would serve as the guiding tool while developing and implementing a long-term flexibilization road map for the county.
In future, these low load test runs will allow the utility to identify their ability and adaptability to reduce its generation when asked by the system operator for integrating more renewable energy and remain synchronized with the power grid. The test runs are the building blocks to the adoption of the nationwide roadmap for flexible operations of coal-power plants, which is a key strategy to meet India’s ambitious target of 175 GW RE addition by 2022.
Recently GTG-RISE, with its aim at scaling up, has partnered with Karnataka Power Corporation Limited (KPCL) to support its efforts on making its coal plant more flexible. The results from USAID’s pilot on flexible operation of coal-based power plant implemented in partnership with Central generating utility, NTPC Ltd. and state utility in Gujarat is now being adopted by the state utility in Karnataka i.e. Karnataka Power Corporation Limited (KPCL). The state generator approached USAID to replicate the work on coal flexibility and learn from the experiences of the pilot undertaken as a part of USAID’s GTG – Renewable Integration and Sustainable Energy (RISE) project.
- GTG-RISE is now assisting NTPC and GSECL in developing the regulatory and investment case scenarios for flexible operations
- In the next one (1) year, GTG-RISE shall assist NTPC and GSECL in preparing fleet wide strategies and support in implementation of identified interventions in select units
- Similar to NTPC, GTG-RISE to assist GSECL in seeking regulatory approval from Hon’ble GERC for compensation of its state units (January – September 2020)
- GTG-RISE to assist NTPC and GSECL in preparing fleet wide strategies and support in implementation of identified interventions in select units (Dec 2020)
The next stage of the pilot aims at providing strategic support to NTPC and GSECL, and also build the business case for policy and regulatory changes to enable flexibility requirements for coal-based stations and shall further contribute to India’s efforts to achieve fleet wide coal flexibility target. GTG-RISE is preparing a paper to advise India’s regulators on what they can do to support coal power plant flexing in India, including necessary compensation mechanisms for regulated power plants and changes to market mechanisms to accommodate various costs of start-up and load-following. GTG-RISE presented the key recommendations of the Draft Regulatory paper on its damage cost analysis to Hon’ble CERC on 5th Feb. 2019. The key recommendations & takeaways of the draft regulatory paper presented to CERC are highlighted below:
Compensation Mechanism required for additional CAPEX and OPEX in units to be subjected to below 55% is required.
Standardization of operation procedures to address flexing requirements
Fleet wide strategy for NTPC and other state utilities is required for pan India involvement.
Pilot Test Runs are required to assess the unit’s ability to adopt flexible measures in the long run.
The damage cost modeling analysis undertaken by the GTG-RISE regulatory paper is also acknowledged and referred by CEA in its upcoming report on Flexible Operations of Thermal Power Plants.
Events & Activities
To share knowledge with and train stakeholders, various workshops, bootcamps and executive exchange programs have been organized, under the USAID’s GTG program, on Coal Generation Flexibility so far.
Pilot Review Board (PRB)
The central component of GTG, RISE initiative, aims to design, implement and scale-up series of prioritized innovation pilots that support the integration of RE into the grid. Each pilot has its own implementation roadmap, stakeholder commitments, coordination and collaborations and periodic reviews by appropriate Government and regulatory counterparts. Towards this, a ‘Pilot Review Board’ (PRB) has been established for each pilot with an aim to promote transparency, ownership and accountability with the key GOI counterpart and other key stakeholders. PRB envisages to guide to address challenges, support stakeholder participation, help promote pilot awareness and lessons learned, and contribute to the sustainability of the individual pilots. PRBs is also there to review the ongoing performance of pilot activities and to recommend corrective action to maximize sustainability and minimize risk if any. Likewise PRBs will also review the challenges met or overcome in the scaling of pilot activities and make recommendations to support scaling.
PRB Structure and Members
Each innovative pilot requires different skill sets of technical expertise and respectively necessitates separate PRB for the pilot. The nominated PRB members represent policy makers, state and central regulatory bodies, grid operators, relevant utilities and even representatives from Original Equipment Manufacturers (OEMs)/Associations. Supported by GTG-RISE team, USAID’s Contracting Officer Representative (COR) for GTG-RISE initiative is the convener of the PRB. The PRB Members details for pilot on flexible operation of coal power plants are provided below:
|Member Name||Member Designation||Member Organization|
|B C Mallick||Chief Engineer||Central Electricity Authority (CEA)|
|Alok Kumar||Sr. Dy. General Manager||POSOCO|
|Saif Rehman||Dy. Manager||POSOCO|
|Somesh Bandyopadhyay||General Manager||NTPC|
|Arun Kumar Roy||Deputy General Manager||NTPC|
|B A Gandhi||Executive Engineer||GSECL|
|Monali Zeya Hazra||Contracting Officer Representation (COR)||USAID/India GTG-RISE|
|Shubhranshu Patnaik||Chief of Party (COP)||USAID GTG-RISE Initiative|