Work example: wind energy and storage 2012

SNOHOMISH COUNTY PUD NO.1

Wheatfield Wind – Management and Energy Storage Considerations

Power and Business Services



Limited Generation Flexibility:PUD electricity supply

81% - Bonneville Power Administration7% - Wind Energy Purchases4% - Jackson Hydroelectric Project4% - Everett Cogeneration/Hampton Biomass Projects3% - Long Term Contracts1% - Klickitat Landfill Gas

Note: not including projected addition of small hydro units



Hay Canyon (Iberdrola Contract) 100.8MWh MWh Capacity @ $75.01 per*

Wheatfield 96.6MWh Capacity at $77.50 per* BPA SLICE averaging $30 per MWh Disproportionate Wind Generation Capacity to non-

Wind dispatchable Snohomish Resources Increasing urgency to focus on Power Scheduling

mechanics:balancing resource to load consistentlyoptimizing BPA 2011 SLICE contractual rights and river managementmaintaining District integrity and reliability within BPA Control Area

* contractual cost – not defrayed by RECSs





http://transmission.bpa.gov/business/operations/Wind/WindAnimation.aspx



Optimal storage v generation through a twenty-four hour scheduling day

http://transmission.bpa.gov/business/operations/Wind/WindAnimation.aspx



Augurs increasing “displacement”, or spilling of hydropower to allow for wind generation



Real-Time responsibilities first 30 minutes every hour

• Load forecasting and resources balancing• Predicting wind generation variances, compensatory adjustment of SLICE, and

marketing length in a wind-saturated market• ICAP marketing operations through Columbia Grid participation• Precise allocation of NT and PTP resources, with POD, POR and Zonal designations• “Transassigning” surplus transmission• Comprehensively managing the District’s share of six (6) hydro plants on the

Columbia River within “hard” BPA flow constraints dynamically within SLICE 2011. Fifteen (15) minute estimate to run “simulator” for SNO share

• Creating market and physical path tags for all internal and external Control Areas purchases

• Communicating hourly Wheatfield generation forecasts to Horizon Wind (ROCC)

Shaping Wind



Energy Utilities are increasingly pursuing energy storage solutions to “smooth” their wind generation, mitigating large unanticipated fluctuations in output. A variety of energy storage methods are being considered for resource to load congruency, frequency regulation, containing wind integration fees charged by Control Areas, and efficiencies of hour-ahead transmission line capacity reservations.

Energy Storage Methods

Flywheel Energy storage is based on mechanical inertia. A heavy rotating disc is accelerated by

an electric motor, which acts as a generator on reversal, slowing down the disc and generating electricity. Electricity is stored as the kinetic energy of the disc. It can be a motor at one moment and a generator the next.A system installed in Coral Bay, Western Australia, uses wind turbines coupled with a flywheel system and low load diesel (LLD) technology resulting in a better than 60% wind contribution to the town grid.

Hydrogen Hydrogen is also being developed as an electrical storage process. Hydrogen is

produced (using electrical energy and/or heat), then usually compressed or liquefied, stored and then converted back to electrical energy and/or heat. However, the conversion process to electricity is through a combustion turbine (CT), or fuel cell, not readily feasible for the District.




Compressed Air A grid energy storage method is to use light load (LLH) or renewably generated

electricity to compress air, which is usually stored in old mines or some other geological feature. During peak load periods or sharp ramp-up demand, the compressed air is heated with a small amount of natural gas and then goes through turboexpanders to generate electricity.

Pumped Water• Pumped storage hydroelectricity is used to even out daily load shapes by pumping

water to a high storage reservoir during LLH hours and weekends. During peak load hours, this water can be used as a high value rapid-response reserve. Pumped storage recovers about 75% of the energy consumed, and is currently the most cost-effective form of mass power storage. The chief difficulty with pumped storage is that it usually requires two nearby reservoirs at considerably different heights, and is capital intensive.




Flow Batteries Flow batteries are rechargeable. A flow battery typically uses liquid

electrolytes that react, exchanging ions and electrons when pumped together into a battery cell stack. The reaction in the cell membrane can either discharge or charge the electrolytes. It’s all reversible. Storage capacity is increased by simply increasing the size of the electrolyte tanks.A company called Xtreme Power, on surface, seems to promise a viable energy storage solution for Wheatfield Wind generation output subject to potential ROI. Xtreme Power claims to have developed new technology using dry cell batteries, in a modular, scalable system with up to 100MWh of storage capacity. They are currently installing a battery storage system for a Maui, Hawaii 30MWwind farm. The state wants 70% of its energy needs met with renewables by 2030.



Xtreme Power Wind Management Claims Power capacity up to 100MW Power storage up to 500MWh Cycle efficiency greater than 95% each direction Automatic communication with transmission grid and SCADA systems Prevents curtailments due to grid constraints or low demand Cost-effective solution to ramp-up / ramp-down excursions





http://transmission.bpa.gov/Business/Operations/Wind/baltwg.aspx







ENERGY STORAGE CONSIDERATIONS – NEAR FUTURE

Wind capacity doubles within last 3 years in Washington, Oregon and California By 2013, wind capacity expected to double again California just increased renewable energy standard. Will need more RECs. REC demand drives increasing production of renewable energy, potentially disrupting

Mid-Columbia markets to ruinous conditions 15% Northwest wind farm energy purchased by public utilities. BPA manages 75%

region’s high voltage transmission system, including most sections serving the wind farms.

Disproportionate displacement of hydropower to accommodate wind production growth Routine spilling will harm fish and not a strategic solution Curtailing wind undermines its economics by foregoing tax and renewable energy

credits BPA ongoing pressure to increase wind integration fees up to quadruple current rates Consistent operational problems when BPA wind integration reaches total capacity of

6,000MW, projected in 2013



Moojen Solution

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Work example: wind energy and storage 2012