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Donald R. Fosnacht, Ph.D.
Hull Rust Mine Panorama, Hibbing Minnesota
Meeting State Mandates for Renewable Power Generation
Minnesota renewable energy standard (MN Statute 216B.1691: 25% renewable by 2025 for non‐nuclear power utilities and 30% by utilities with nuclear capability). Minnesota’s climate change goal (MN Statute 216H.02: 30% reduction by 2025 and 80% reduction in green house gases by 2050)
How can increasing amounts of renewable energy be integrated into the power grid system without causing significant disturbance?
Solar and wind energy are intermittent energy resourcesAs more and more wind and solar energy is brought “on‐line” they will have increasing effects on system stabilityEnergy managers believe that penetration beyond 12% of overall power generation will require fossil fuel based peaking plants and various types of energy storage systems
Why? Balance Intermittent Power Source Generation with Need
Load versus Wind Power Generation for MN on 1/3/2010 (Source: MISO)
Pumped Hydro Energy StorageKnown technology over 40 sites exist in US todayVery high capacityPredictable capital and operating costsEasily integrated into the grid management systemRequires significant water resourceRequires power source to move water from lower to upper reservoirModern variable speed systems now achieve 86% overall efficiency
It should be viewed as a facilitation technology for renewable energy implementation
Existing PHES Facilities in USA Courtesy of Rick Miller, HDR Inc.
Various Energy Strategies are under development
Ibrahim, H., Ilinca, A., and Perron, J., 2008, Energy storage systems – characteristics and comparisons: Renewable and Sustainable Energy Reviews.
Cost and Storage Capability are key to large scale renewable implementation
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CAES PHES PHES (variable speed)
Na - S Battery LA Battery (FC) LA Battery (VRLA)
Zn-Br Battery Ni/Cd Battery
Annual Costs for 8-hr Bulk Energy Storage Technologies ($/kW-year)
Source: Schoenung, S. M., and Hassenzahl, W. V., 2003, Long- vs. short-term energy storage technologies analysis: A life cycle cost study:A study for the DOE Energy Storage Systems Program: Sandia National Laboratories Report SAND2003-2783, 60 p.
Basic Concept Diagram
http://upload.wikimedia.org/wikipedia/commons/9/9a/Pumpstor_racoon_mtn.jpg]
Basic Operating ConceptDuring off‐peak periods, wind
energy is plentiful and low priced
Upper, lower reservoirs are existing, out of
service, Iron Range open pit mines ?
PHES facility stores low price energy, releasing it during peak periods when demand
and price is high
Comparison of Technologies
Bogenrieder, W.: 2.6. Pumped storage power plants. Heinloth, K. (ed.). SpringerMaterials ‐ The Landolt‐Börnstein Database DOI: 10.1007/10858992_7
Storage Benefits need to be reflected in revenue and cost equations ‐‐ PHES can:
Allow firming of overall capacity from renewable sourcesSignificant capacity per unit capital costLong term facility lifeCan follow load requirementProvide a fast acting spin reserveHelp regulate system voltage requirements
Provide transmission systems support and buffer possible congestionEmploy time of use energy cost managementDemand charge managementAdd soaking capabilitiesProvide reliable power quality
Overall Energy Efficiency for PHES Systems ‐‐ Example
Bogenrieder, W.: 2.6. Pumped storage power plants. Heinloth, K. (ed.). SpringerMaterials ‐ The Landolt‐BörnsteinDatabase DOI: 10.1007/10858992_7
Modern variable speed systems can approach 86% efficiency
Minnesota OpportunityTake advantage of water resources on MN’s Iron Range (MIR) from abandoned mine pitsClose proximity to Minnesota Power’s DC transmission line from North Dakota wind resourcesGreat River Energy and Minnesota Power have ample transmission line capability near the various mining sitesAllow potential large scale energy storage using a proven technology to aid in adoption of renewable energy from wind
Why this project?Key questions that need study:
What potential sites exist on the MIR?What makes a good pumped storage site? Are there potential sites for closed loop pumped storage in Northeastern Minnesota with sufficient scale to support a project from previous mining activities?
Can a closed loop pumped storage project co‐exist with present and/or future mining activities?How can PHES be implemented in an environmentally benign way?Are any changes needed to state policy to remove roadblocks that would impede implementation of the technology that balances the value of the environment, minerals and renewable generation?
UM – diverse input to projectUM Participants
Natural Resources Research InstituteUMD Civil engineeringSaint Anthony Falls LaboratoryHumphrey Institute
Commercial ParticipantsGreat River EnergyMinnesota PowerBarr Engineering
Four focus areasEnvironmental IssuesFacilities requirementsGeotechnical parametersPolicy and economic factors
Geotechnical TeamAssess the integrity and properties of the rock at any selected locationDetermine the geologic conditions that exist at any site and the likelihood for coherent rock structures for the upper and lower reservoir basin Generate maps and datasets illustrating site characteristics Lead assessment of alternative land useAssess integration of pumped hydro storage design with the long‐range mining plans of existing mining operationsCharacterize select waste materials for economic and environmental purposes
Geotechnical TeamGeotechnical Assessment‐ Rock Mechanics – Sampling & Testing/GIS;‐Mineral Assessment/Permitting/GIS;‐ Rock Stratification/Geological Mapping/GIS;‐ Geological Integrity/Geological Mapping/GIS;‐Minerals Usage and Value/GIS;‐Waste Rock Characterization & Analysis/GIS; and‐ Archeology/Historic Sites/GIS.
Facilities TeamSurvey of existing pumped hydro facilities, overview of overall systems/components and overview of design variations Component characterizations including cost and potential size limitations (civil and mechanical works) Review of current economic analysis of pumped hydro plant construction (i.e., cost/MW(h)) including currently reported estimates and models
Critical Component areasReservoirs Mechanical and Electrical
Sealing mechanisms and construction techniquesOverflow controlsLeakage monitoringIntake and associated gatesPenstock to pumphouseEmbankment/dam constructionRock walls/manifolds/surge tanks
Pump/turbineMotor/generatorDraft tubeStart‐up systemsPumpsCompressorsGate ActuatorsControls/meters/actuatorsTransmission lines and transmission equipment
Consider environmental impacts of both mining and PHES implementation
Study areas:
Environmental Team
1. Geology and soil 2. Water resources
• groundwater & surface water• water quality & quantity• greenhouse gases
3. Terrestrial resources• wetlands and vegetation
4. Wildlife 5. Threatened & endangered
species 6. Cultural Resources 7. Air quality & Noise
8. Hazardous Materials
Permit assessmentState permits
1. Minnesota Public Utility Commission (PUC) permits
2. DNR Water Appropriation Permit3. MPCA National Pollutant Discharge
Elimination System (NPDES) Permit
4. Dam Safety Permit5. Wetland Conservation Act (WCA)
compliance6. MPCA Industrial Stormwater
Permit
Federal permits1. Federal Energy Regulatory
Commission (FERC) Licensing
2. Section 404 Permit (if wetlands are impacted)
FERC “Initial Consultation List”:http://www.ferc.gov/industries/hydropower/enviro/consultlist.aspx?State=Minnesota
Surface and Ground Water Exchange1. Within what area surrounding the pit will groundwater
flow (direction and magnitude) be changed?2. How might these changes affect the oxidation/reduction
of iron and sulfur within the affected area and therefore, the water quality in pit lakes?
3. How might PHES development affect ongoing and future mine land reclamation efforts?
4. What is the potential for PHES to exacerbate existing water resource issues in the region? (e.g. sulfate, fish‐mercury, heavy metals, sedimentation, et al.)
Conceptual model for PHES effects on water resources under development
Modeling of System
Mean WL
HWL
LWL
dLdhK− Long‐term average
flux of GW to reservoir
Short‐term exchange of GW
with SW in reservoir
Surficial geology, unconsolidated,
high K
Bedrock geology, consolidated,
low K
Pump discharge into complex
limnology of deep pit reservoirs
( )tQP
•Two mechanisms foreseen for altering mass transfer from rocks to SW
1. Wetting/drying cycles speed oxidation processes
2. Hydrostatic pumping increase exchange with groundwater
•Pumping drawdown may influence surficial hydrogeology that influences surficial hydrologic budget
•Characterizing hydraulic properties of fracture dominated rock
Policy TeamAssess land use and mineral rights issues that would be impacted by locating PHES facilities on the MIR.Identify socio‐political factors that affect PHES deployment on the MIR, including key stakeholders and their perception of PHES.Determine policy implications of closed loop PHES on the MIR and identify legal or regulatory barriers to implementation. Identify life cycle parameters that will need to be quantified in more detail in future studiesOutline potential benefit stream from PHES deployment
PHES implications – some initial considerations(1) Improve System ReliabilityPumped storage is alternative to natural gas power plants for providing back‐up generation for variable generation• Pumped storage also serves as a load during pumping. Therefore, it
could reduce episodes when wind producers are asked to shut down because there is not enough demand, termed curtailments.• Under most power purchase agreements, utilities bear the risk of
curtailment
(2) Reduce transmission congestion • A high location marginal price (LMP) is a signal of weakness in the power system. High LMPs can be alleviated with either new generation or new transmission.
• PHES is an alternative to building additional transmission• Generators (e.g. PHES) capable of closely matching LMP patterns
on the local region are of higher value to the system as they are more effective at reducing need for, and stress on, the transmission network
PHES implications – continued
(3) Arbitrage electricity prices and provide ancillary services
• The profit of the pumped‐storage plant is maximized by operating the facility as a generator when the LMP is high and as a pump when the LMP is low
• The revenue of a pumped‐storage unit includes the revenue received by selling energy when it is in the generating mode and by being accepted in the non‐synchronous reserve market when not in the generating or pumping mode
(4) Offer system balancing services
• Bid the services of pumped storage into the ancillary markets when it is not pumping or generating
Relationship of PHES to Minnesota’s Renewable Energy Standard
• Unclear whether PHES would be treated as renewable power.• Pro ‐ PHES operates similar to a hydroelectric facility in that it
releases water through turbines to generate electricity.• Con ‐ the fuel for pumped storage is off‐peak power, not water.
The pumped storage facility is a net consumer of energy.
• Current MN policy states that hydroelectric with a capacity of less than 100 MW qualifies as an eligible energy technology for purposes of satisfying the renewable energy standard
• PHES facilities will most likely need to be larger than 100 MW to be viable economically – this is a potential policy barrier.
Potential MIR Schemes•Pit‐to‐pit
•Most difficult to find in topography•Reduced cost due to completed reservoirs•May require patches to slow leakage
•Natural Pit to Constructed Upper reservoir•Reservoir Construction•Easier to find in topography
•Isolated Pit to Constructed Upper Reservoir
Project StatusMilestone Completion Date
• Tour of Ludington, MI PHES Facility 30‐Jul‐10• PHES Policy Group Focus Meeting @ GRE 28‐Sep‐10• Tour of Selected Potential PHES Sites 14‐Oct‐10• Research, Literature Review Underway• Compile, Analyze GIS Data Underway• Geological Mapping of Potential Sites Underway
Future ActivitiesMilestone Completion Date
• Develop Site Assessment Guidelines Underway• Develop Site Survey Plan (locations) Underway• Review Site Survey Plan w/DNR Underway• Conduct Site Survey Jan‐2011• Geological Sampling Feb‐2011• Site Ranking Feb‐2011• Policy Factors Review Mar‐2011• Draft Project Report Mar‐2011• Final Project Report Apr‐2011• PHES Project Completion Date 30‐Jun‐2011
Participants in Study
Dr. Donald Fosnacht, NRRI, Principle InvestigatorMr. Dwight Anderson, Minnesota PowerMr. Vince Herda, Great River Energy
Facilities TeamMr. Jeffrey Marr, St. Anthony Falls Laboratory, UMTC*Dr. John Gulliver, Civil Engineering, UMTCMr. Matthew Lueker, St. Anthony Falls Laboratory, UMTCMr. David Aspie, Minnesota Power
Geotechnical TeamMr. Steven Hauck, NRRI*Dr. Carlos Carranza‐Torres, Civil Engineering, UMDDr. George Hudak, NRRIMr. Mark Severson, NRRIMr. John Heine, NRRIMr. David Aspie, Minnesota PowerMs. Rochon Kinney, Minnesota PowerMr. Carl Sulzer, Great River EnergyMs. Julie Oreskovich, NRRI
Policy TeamDr. Elizabeth Wilson, Humphrey Institute of Public Affairs*Melisa Pollak, Humphrey Institute of Public AffairsNathan Paine, Humphrey Institute of Public AffairsMr. Dwight Anderson, Minnesota PowerMr. Steve Garvey, Minnesota PowerMs. Cindy Hammerlund, Minnesota PowerMr. Mike Klopp, Minnesota PowerMr. Bob Ambrose, Great River EnergyMr. Mark Fagan, Great River EnergyMr. Jay Porter, Great River EnergyMr. Bob Sandberg, Great River Energy
Environmental TeamDr. Nathan Johnson, Civil Engineering UMD*Xianben Zhu, Civil Engineering UMDDr. Rich Axler, NRRIMr. Kurt Johnson, NRRIMr. Blake Francis, Minnesota PowerMr. Mark Strohfus, Great River Energy
Overall Coordination
*Team Leaders
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