FLEXIBILITY: KEY TO UNLOCKING POWER SYSTEM TRANSFORMATION Prospects for Solar PV and Storage Technologies in the Future Energy Landscape Singapore
OUTLINE About 21CPP Power System Transformation: US Snapshot Background on RE Integration and Flexibility 21CPP-IEA Power Plant Flexibility Study Summary
21CPP OBJECTIVES: POWER SYSTEM TRANSFORMATION
21CPP WORK STREAMS Annual Program of Work Includes: Thought-Leadership studies that focus on generic power system transformation topics across the world In-country technical assistance, often as part of a larger development assistance effort, focused on policy, regulatory, and technological progress; grid integration studies often highlight this work. Information exchange, capacity building, fellowship programs, and other exercises to share lessons-learned and knowledge transfer.
U.S. POWER GENERATION DYNAMICS 2000 Annual U.S. Net Generation by Fuel 1800 1600 Coal 1400 Terawatt-hours 1200 1000 800 600 400 200 0 1950 1952 1954 1956 1958 1960 1962 1964 Petrol 1966 1968 1970 1972 1974 1976 1978 1980 1982 Geothermal Biopower 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 Hydro Natural Gas 2004 2006 2008 2010 2012 2014 Nuclear Wind Solar 2016 2018
U.S. POWER GENERATION DYNAMICS 2000 Annual U.S. Net Generation by Fuel 1800 Coal 1600 1400 Terawatt-hours 1200 1000 800 600 400 200 0 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 Nuclear Hydro Natural Gas 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 Non-Hydro RE Petroleum 2014 2016 2018
U.S. POWER GENERATION DYNAMICS 2000 Annual U.S. Net Generation by Fuel 1800 1600 1400 Coal Terawatt-hours 1200 1000 800 600 Nuclear Natural Gas All RE 400 200 0 Petroleum 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018
U.S. POWER GENERATION DYNAMICS 2000 Annual U.S. Net Generation by Fuel Terawatt-hours 1800 1600 1400 1200 1000 800 600 Coal Zero Carbon (burner-tip) Natural Gas 400 200 0 Petroleum 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018
BACKGROUND ON RE INTEGRATION AND FLEXIBILITY Source: California ISO
GRID OPERATIONS: A MATTER OF BALANCE Supply Supply Components Demand Components Storage Renewable Generators Conventional Generators Storage Electric Vehicles Building End Uses Demand Supply and demand are both variable. The power system keeps these in balance at all times.
WIND AND SOLAR ADD VARIABILITY TO THE SUPPLY SIDE Source: NREL Report No. FS-6A20-63039
ACCESSING FLEXIBILITY IS A KEY OBJECTIVE OF RE INTEGRATION Physical power system: generators, transmission, storage, interconnection Institutional system: operations (e.g., scheduling, dispatch, forecasting), market rules, collaboration with neighbors Focus of most grid integration efforts Physical system Market and institutional filter Power system operation, reliability, cost Power system operation (and grid integration) relies on both
FREQUENTLY USED OPTIONS TO INCREASE FLEXIBILITY Source: Cochran et al. (2014). Flexibility in 21 st Century Power Systems.
FREQUENTLY USED OPTIONS TO INCREASE FLEXIBILITY
21CPP-IEA POWER PLANT FLEXIBILITY STUDY Released at CEM 9 (May 2018) in Copenhagen
ADVANCED POWER PLANT FLEXIBILITY CAMPAIGN Campaign Co-leads Non-government partners Participating CEM Members Now 14 partner countries and 14 industry and NGO partners membership has increased throughout the duration of the campaign
RELEVANT DIMENSIONS FOR UNLOCKING SYSTEM FLEXIBILITY Technical, economic and institutional policy layers mutually influence each other and have to be addressed in consistent way to enhance power system flexibility.
FLEXIBILITY NEEDED ACROSS A WIDE- RANGE OF TIME SCALES Timescale Issue Short-term flexibility Subseconds to seconds Address system stability, i.e. withstanding large disturbances such as loosing a large power plant Seconds to minutes Address fluctuations in the balance of demand and supply, such as random fluctuations in power demand Medium-term flexibility Long-term flexibility Minutes to hours Hours to days Days to months Months to years Manage ramps in the balance of supply and demand, e.g. increasing electricity demand following sunrise or rising net load at sunset. Decide how many thermal plants should remain connected to and running on the system. Managing scheduled maintenance of power plants and larger periods of surplus or deficit of energy, e.g., hydropower availability during wet/dry season Balance seasonal and inter-annual availability of variable generation (often influenced by weather) and electricity demand System flexibility addresses a set of issues, spanning timescales from subseconds to years.
POLICY GUIDELINES FOR FLEXIBILITY DEPLOYMENT Power plant flexibility can be rolled out successfully by following a set of best practice policy guidelines.
CONSIDERATION #1 ASSESS Building up a flexibility inventory can allow policy makers to see what options are available today and how to plan for future flexibility requirements
CONSIDERATION #2 ENGAGE Domestic and international stakeholder engagement can help build momentum for embedding flexibility in modern power systems
CONSIDERATION #3 ENHANCE Enhancing system-wide flexibility requires coordinating technical options from operational changes to demand-side measures
CONSIDERATION #4 UNLOCK Review must-run requirements for power plants Oversee the review of electricity and fuel contracts to enhance flexibility through contract flexibility Allow VRE participation in reserve provision Generation/Load (MW) 30 000 25 000 20 000 15 000 10 000 5 000 0 31 Dec 00:00 31 Dec 06:00 31 Dec 12:00 Core RE2 31 Dec 18:00 30 000 25 000 20 000 15 000 10 000 5 000 0 31 Dec 00:00 31 Dec 06:00 Plant and contract flex RE2 31 Dec 12:00 31 Dec 18:00 NUCLEAR COAL BIOMASS_WASTE OtherGas CCGT HYDRO SOLAR WIND OCGT DIESEL VRE curtailment Load Net Load Unlocking flexibility from existing assets can be a cost-effective approach but should be informed by cost-benefit analyses
CONSIDERATION #5 -- INCENTIVIZE In liberalized markets Improve wholesale market design Implement market instruments for all relevant system services Introduce capacity mechanisms that value flexibility In regulated markets Allow cost recovery for retrofit investments Provide incentives that allow for resilient, high-flexibility components in new power plants Introduce fair remuneration that accounts for the system value of flexibility
CONSIDERATION #6 ROADMAP Encourage the inclusion of flexibility assessments in planned system adequacy assessments Request state-of-the-art decision support tools for long-term planning purposes Encourage the integration of generation and transmission investment planning Assess costs and benefit of demand-side resources and electricity storage options Long-term system transformation is an iterative process that requires regular evaluation and update of system planning
MOORFLEX: FLEXIBLE COAL AND CO- GENERATION Measures Results Co-generation plant located in Hamburg with 827MWe capacity. Plant was unable to obtain sufficient revenue from base-load operation under current market conditions. Reduction of minimum stable output levels from 35% to 26% Optimization of control loops and operation modes Retrofitting with flue gas dampers to regulate cooling Reduction of minimum stable output level lead to reduced number of start-ups and shutdowns associated with increased costs Faster ramping rates: able to ramp at 48MW/min and up to 90MW/min under special conditions Improved start-up: Warm-cold 20% faster Warm 42%-50% faster Hot 40 46% faster Source: Case-study provided by MHPS, March 2018. Vattenfall (2016) Increasing power plant flexibility can enable existing assets to remain profitable despite changing market conditions.
LA CASELLA: CCGT REFURBISHMENT FOR INCREASED FLEXIBILITY Built in the 1970s as an oil-fired plant for baseload operation. Converted to a CCGT with four 370MW units between 2000 and 2003. First intervention in 2008, second in 2014 to adapt to new market requirements: competition and reserve provision. 1 st set of measures Results Exploration of plant s real limits and constraints Equipment modernization and partial automation Update to operational procedures 2 nd set of measures Optimisation of combustion behaviour at low loads Study of component limits under increased stress conditions, particularly HRSG unit. Measurement and redesign of turbine to reduce rotor stress Start-up time improvement: Warm 50% faster Cold 20% faster Reduced minimum stable level from 230 MW to 170 MW and faster ramping Ability to provide reserve and meet emissions requirements Reduced damage to equipment in the face of faster ramps Data availability and experiences have been deployed across ENEL s fleet Source: ENEL Improving plant performance is an iterative process that extend the plant s lifetime, while ensuring that changing market requirements and regulations are upheld.
KYUSHU: FLEET COORDINATION FOR INCREASED FLEXIBILITY With 6 GW installed PV capacity, 16 GW peak load and 8 GW minimum daytime load, Japan s southern-most main island, Kyushu, has the highest VRE penetration in Japan. 6 dispatch rules developed by the Japanese Organization for Cross-regional Coordination of Transmission Operators: Avoid generation from reservoirs and PSH during daytime. Prioritise electricity surplus absorption by PSH. Reduce thermal plant output to minimum stable levels. Export surplus electricity through cross-regional interconnectors. Reduce biomass power plant output. Curtail solar PV and wind as a last resort. Source: Kyushu EPCO Avoiding thermal generation shutdown is crucial as their start-up times range between 2 and 8 hours At sun-down solar PV output decreases at ~1.3GW/hour High solar PV penetration highlights the importance of improving forecasting Introducing protocols for coordinating power plant response to manage VRE variability can be useful in maintaining system stability at high VRE shares.
MAIN FINDINGS Across power systems with economic dispatch, increasing VRE penetration is redefining the way conventional assets operate The case-studies show that there is a range of technically and economically feasible solutions to improve plant flexibility and reduce VRE curtailment Regulation and market rules are crucial in unlocking flexibility across all technologies Generation technologies vary in their ability to provide flexibility across time-frames Main technical parameters Minimum stable output Reduces plant shut-down and costs Ramp rate and start-up Improve response time to VRE variability Minimum up and down times Improved scheduling flexibility
FLEXIBLE THERMAL GENERATION BUSINESS AS USUAL ALREADY TODAY Conventional electricity generation in Germany in November 2017 80 Other 70 60 Pumped storage hydro 50 Natural Gas GW 40 30 Hard coal 20 10 Lignite 0 1 5 9 13 17 21 26 30 November 2017 Nuclear Source: Agora (2018b), Die Energiewende im Stromsektor: Stand der Dinge 2017 The significant share of relatively inflexible generation, coupled with high VRE variability, make flexibility a priority for the operation of Germany s power system
CAMPAIGN CONTINUATION: NEW FOCUS ON SYSTEM FLEXIBILITY Continuation of the APPF campaign with a wider scope on power system flexibility 3 deep-dive workshops
KEY MESSAGES Power plants are one option to provide system flexibility, but many other options are available in modern power systems. Experience and examples highlighted in the report establish that many, if not all, power plant technologies can operate flexibly and across multiple timescales of power system operation. The role of existing thermal power plants is transitioning in many modern power systems toward more flexible modes of operation and, at times, reduced operating hours. Significant system flexibility lies latent in many power plants; global experience suggests a range of known strategies are available to unlock that flexibility, many of which are non-technical. Generators that were initially designed and operated as inflexible have been successfully engineered into highly flexible assets Incorporating regular flexibility assessments into planning and strategy dialogues is key. Established decision support tools can be used to assess flexibility requirements, understand the value of proposed changes, and plan for the future.
THANK YOU Visit us at: https://21stcenturypower.org Jeffrey.logan@nrel.gov
TEN STEPS FOR FLEXIBILITY AT THE POWER PLANT LEVEL 1. Raise the awareness for flexibility: Provide background information about the need for flexibility, explain the necessity and impact on the O&M of the plant, and initiate training programs. 2. Check the status of the plant and identify bottlenecks and limitations with respect to flexible operation: Consult with OEMs to assess the influences of low load operation and temperature and pressure gradients on main components and equipment. Ensure smooth operation of all control loops. 3. Plan and execute test runs to evaluate the plant flexibility potential. Create transparency about the plant performance with respect to minimal load, start-up and cycling behavior in the current setup. Identify constraints and process limitations as well as improvement potential. 4. Optimize the information and communication system: This is the most cost-effective way to enhance the flexibility of the plant. A certain level of automation is a prerequisite for tapping this potential. 5. Implement mitigation measures to manage the consequences of flexible / cycling operation. This includes a reassessment of all O&M procedures. The use of appropriate condition monitoring systems is essential. 6. Optimize combustion: Stable combustion is the key aspect to ensure minimum load operation. 7. Optimize start-up procedures: Check start-up related temperature measurements and consider replacement; automate start-up procedures. 8. Improve the plant efficiency at part load and the dynamic behavior of the plant: Use the potential of the water-steam cycle and enhance the performance of important equipment and components, e.g. fans or feed water pumps. 9. Improve the fuel quality: The better the fuel quality the better the combustion process. 10. Consider storage options to enhance the overall flexibility performance of the plant. This refers to battery or thermal storage systems.