Energy Storage for the Grid - PDF Free Download

Grid Operations A wide range of timescales 1 sec Inertial Governor Auto Generation Control 1 min 10 min 1 hr 1 day 1 wk Timescales for Grid Operations Economic Dispatch Unit Commitment Power Energy Each application for energy storage should enhance grid operations and performance at a price competitive with that of conventional approaches GE Copyright 2011 3

Potential Applications Application Type Description Value Energy Arbitrage Energy Buy low, sell high Generation Capacity Equipment Capacity Line Congestion Wind/Solar Smoothing Frequency Regulation Reserves Governor / Inertial Energy Energy Energy Power Power Power Power Time shift energy from off-peak to peak load Reduce flow through overloaded lines and transformers Time shift delivery of renewable energy during congestion Reduce ramp rates of wind and solar plants Rapidly inject and remove power for short intervals Dispatch power in < 10 minutes Provide dynamic equivalents of synchronous generators Displaces most expensive generation Defers investment in new generation Defers investment in new equipment Delays transmission line reinforcement Contributes to reserve & regulation requirements Contributes to regulation requirements Contributes to system reserves Reduces severity of frequency variations The cost of storage should be compared against conventional approaches Power Energy GE Copyright 2011 4

Energy Arbitrage Buy low, sell high Economics are driven by the spread between peak and off-peak prices Spread expected to drop with more wind power Example: 100 MW, 10hr storage system (70% efficiency) 35% wind and solar, by energy in NV, AZ, NM, CO, WY With more wind, the value of energy storage for arbitrage is not high Still need to figure out when to charge/discharge Source: NREL, Western Wind and Solar Integration Study GE Copyright 2011 5

Transmission Congestion Shift wind energy to a later time Transmission congestion when wind is strong in wind power rich areas Storage could shift wind energy that would otherwise be curtailed Future congestion, wind projects and market prices are unknown Could put the storage investment at risk $1,500/kW storage requires >20% wind energy curtailment for positive returns And other risks to cope with Source: GE Paper; IEEE PSCE 2011 GE Copyright 2011 6

Wind and Solar Smoothing Smooth power to reduce variability Aggregating many homes tends to smooth out the load The output of many wind plants is also smoother than a single plant 2 homes 20 homes Load per home Load per home Hour Hour Source: Willis & Rackliffe, Introduction to Integrated Resource T&D Planning GE studies show that the grid can accommodate fast wind variability For local wind/solar smoothing some storage will charge while others discharge In reality the variability smooths itself out GE Copyright 2011 7

Frequency Regulation Quickly Inject/absorb power 5min markets emerging, where storage can participant NYISO Projects being built today 20MW battery, 20MW flywheel Where prices are high (remote areas), good value; GE/GNB Alaska battery 4MW, 15min, 85% efficient $25/MW plus 8yr life seems to make sense at $1,700/kW 1MW Alaska BESS (1994) Alaska BESS cost $2.2M; saved $6.6M of imported diesel fuel over 12yr of operation. Battery exceeded 8yr life estimate GE Copyright 2011 8

Equipment Capacity Reduce flow of electricity when equipment is overloaded Defer investment in new transformer, substation, line by shifting energy from one time to another Duration, severity, and frequency of overloads used to size storage Potentially attractive applications Substations where space is scarce; locations where new lines are tough to build The value for T&D investment deferral should be established on a case-by-case basis GE Copyright 2011 9

Electric Vehicles If 10% of the fleet were EVs, load grew by 5%, for this system If uncontrolled peak load increased. If smart, EVs can be charged at night by lowest cost generation The marginal cost of serving the EV load is much lower when the EVs are smart charged Good value for controlled EV charging Cost savings can be used for customer incentives & charging infrastructure Source: Manz, Miller, Hinkle. Integrating Electric Vehicles into the Power System. CIGRE Symposium, Bologna, Italy, 09/2011 GE Copyright 2011 10

Electric Vehicles CO 2 emissions depend on the generation that charged the vehicle EV miles per kg CO 2 EV produces same CO 2 as a 42 MPG gasoline vehicle Miles per Gallon CO 2 emissions from electric vehicles depend on the emissions from the power plants that charged the vehicles charging strategy matters Source: Manz, Miller, Hinkle. Integrating Electric Vehicles into the Power System. CIGRE Symposium, Bologna, Italy, 09/2011 GE Copyright 2011 11

An example GE Durathon TM System Feeder Current Degradation of Equipment Peak 24 hours Battery charges with wind energy that would otherwise be curtailed and discharges when feeder peak load is exceeded BESS kw Charge BESS w/ wind power Discharge BESS 24 hours GE Copyright 2011 13

Conclusions No problems exists for which storage is the only solution Storage is being built today Frequency regulation and T&D deferral are emerging applications Strong value for niche applications T&D deferral for urban centers with no room for growth Regulation in systems with high fuel costs EVs could significantly increase load Charging strategy matters CO2 footprint depends on generation mix Each application should be assessed on a case-by-case basis GE Copyright 2011

Sources Manz, Keller, Miller, Value Propositions for Utility-scale Energy storage IEEE Power Systems Conference and Exposition, Phoenix, AZ Manz, Miller, Hinkle. Integrating Electric Vehicles into the Power System. CIGRE Symposium, Bologna, Italy, 09/2011 George Hunt, Metlakatla Battery Energy Storage System: 12 years Of Success GNB Industrial Power, Exide Technologies. 2009 Storage Week, San Diego, CA National Renewable Energy Laboratory, Western Wind and Solar Integration Study http://wind.nrel.gov/public/wwsis 15