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OwnerJuly 2015 to presentEl Cerrito

Finding best available technologies for meeting energy needs today and tomorrow: energy efficiency, demand response,, solar, wind, electric vehicles, biofuels and smart grid. It’s all the innovations that make the energy we use more secure, clean, and affordable. The energy world's best hopes lie in what's happening in the digital realm, especially in data analytics.

Thursday, July 24, 2014

Building Science

Back to Smart Efficiency

A. Building Systems Basics
FRIDAY, MARCH 25, 2011
Commercial and residential buildings account for 40% of total energy consumption in the US. Smart Building has the capacity for greatly increasing building system operating efficiency, reducing greenhouse gas emissions and improving comfort and performance of occupants.


B. Lighting Controls/ Daylighting
updated friday, october 7, 2016 
As a nation, we spend about one-quarter of our electricity budge on lighting, but much of this expense is unnecessary. Technologies developed during the past 10 years can help us cut lighting costs by 30 – 60 percent while enhancing lighting quality and reducing environmental impact.


C. HVAC Controls
TUESDAY, DECEMBER 6, 2011
Building operations consume 39% of the energy in the U.S. and HVAC gobbles up a big part of that. However, 9 out of 10 commercial buildings fail to meet fundamental conditions for acceptable comfort and energy efficiency.


(New). Just What is Net Zero Energy?
FRIDAY, SEPTEMBER 20, 2013
(Coming Soon) NZE is frequently bandied about these days, but there is no consensus what the term means.

Superconducting Magnetic Storage (SMES)

More efficient than other storage methods because electric currents encounter almost no resistance



SMES can be used for power quality and increased transmission asst utilitzation
About six small plans are in operation for power quality applications (1 to 3 MW with 1 to 3 seconds of storage)

High temperature superconductors will lower SMES costs

Navigate this Report
Back to Energy Storage Index

1. Background
2. Acronyms/Definitions
3. Business Case
4. Benefits
5. Risks/Issues
6. Next Steps
7. Companies
8. Links

1.Background
  • SMES store energy in the magnetic field created by the flow of direct current in a superconducting coil which has been cryogenically cooled to a temperature below its superconducting critical temperature. A typical SMES system includes three parts: superconducting coil, power conditioning system and cryogenically cooled refrigerator. Once the superconducting coil is charged, the current will not decay and the magnetic energy can be stored indefinitely. The stored energy can be released back to the network by discharging the coil. The power conditioning system uses an inverter/rectifier to transform alternating current (AC) power to direct current or convert DC back to AC power.
  • Superconducting magnetic energy storage systems store energy in the field of a large magnetic coil with direct current flowing. It can be converted back to AC electric current as needed. A magnetic field is created by circulating a DC current in a closed coil of superconducting wire. The path of the coil circulating current can be opened with a solid state switch which is modulated on and off. Due to the high inductance of the coil, when the switch is off (open), the magnetic coil behaves as a current source and will force current into the capacitor which will charge to some voltage level. Proper modulation of the solid-state switch can hold the voltage across the capacitor within the proper operating range of the inverter. An inverter converts the DC voltage into AC power. SMES systems are large and generally used for short durations, such as utility switching events.


2. Acronyms/Definitions
  1. Power Factor -
  2. SMES - Low Temperature Superconducting Magnetic Storage - Cooled by liquid helium Commercially available
  3. SMES - High temperature Superconducting Magnetic Storage - Cooled by liquid nitrogen is still in the development stage and may become a viable commercial energy storage source in the future
  4. Solenoid - A coil wound into a tightly packed helix. In physics, the term solenoid refers to a long, thin loop of wire, often wrapped around a metallic core, which produces a magnetic field when an electric current is passed through it. Solenoids are important because they can create controlled magnetic fields and can be used as electromagnets.

    For small SMES, solenoids are usually used because they are easy to coil and no pre-compression is needed
  5. .
  6. Toroid - A doughnut-shaped object, such as an O-ring. Its annular shape is generated by revolving a plane geometrical figure about an axis external to that figure which is parallel to the plane of the figure and does not intersect the figure.

    Toroidal geometry can help to lessen the external magnetic forces and therefore reduces the size of mechanical support needed. Also, due to the low external magnetic field, toroidal SMES can be located near a utility or customer load. In toroidal SMES, the coil is always under compression by the outer hoops and two disks, one of which is on the top and the other is on the bottom to avoid breakage. Currently, there is little need for toroidal geometry for small SMES, but as the size increases, mechanical forces become more important and the toroidal coil is needed.


3. Business Case
  • SMES is currently used for short duration energy storage. Therefore, SMES is most commonly devoted to improving power quality. If SMES were to be used for utilities it would be a diurnal storage device, charged from base load power at night and meeting peak loads during the day.
  • Economics of Superconducting Magnetic Storage
    • Capital $200-250 per kW
    • Variable $650,000 – 860,000 per KWh
    • Hours 1 second
    • Total Cost $380 – 489 per kW
      $kW + (Hours x $/kWh)


4. Benefits
  • Frequency Regulation - The time delay during charge and discharge is quite short. Power is available almost instantaneously and very high power output can be provided for a brief period of time. Other energy storage methods, such as pumped hydro or compressed air have a substantial time delay associated with the energy conversion of stored mechanical energy back into electricity.
  • Voltage Regulation - SMES is also used in utility applications to provide grid stability in distribution systems. In northern Wisconsin, a string of distributed SMES units was deployed to enhance stability of a transmission loop. The transmission line is subject to large, sudden load changes due to the operation of a paper mill, with the potential for uncontrolled fluctuations and voltage collapse.
  • Power Quality Control - Several 1 MW SMES units are used for power quality control especially to provide power quality at manufacturing plants requiring ultra-clean power, such as microchip fabrication facilities.
  • High Efficiency - The loss of power is less than other storage methods because electric currents encounter almost no resistance. The inverter/rectifier accounts for about 2-3% energy loss in each direction. SMES loses the least amount of electricity in the energy storage process compared to other methods of storing energy. SMES systems are highly efficient; the round-trip efficiency is greater than 95%
  • Reliability - The main parts in a SMES are motionless, which results in high reliability.
  • Fast Charging (within seconds), Because of their very fast charging rate, ECs may be able to recover the energy from many repetitive processes (e.g., braking in cars or descending elevators) that is currently being wasted
  • Service Life - large number of charge-discharge cycles (hundreds of thousands)


5. Risks/Issues
  • Cost - The high cost of superconductors is the primary limitation for commercial use. The cost incurred is higher than other technologies such as capacitors, CAES, flywheels but lower than battery systems.
  • Cryogenics - Cold temperature technology can be a challenge. Energy requirements of refrigeration the cooling requirements incur energy and maintenance costs.
  • Low Energy Density
  • Mechanical Support - Needed because of lorentz forces.
  • Size - To achieve commercially useful levels of storage, around 1 GW·h (3.6 TJ), a SMES installation would need a loop of around 100 miles. This is traditionally pictured as a circle, though in practice it could be more like a rounded rectangle. In either case it would require access to a significant amount of land to house the installation, and to contain the health effects noted below.
  • Manufacturing - There are two manufacturing issues around SMES. The first is the fabrication of bulk cable suitable to carry the current. Most of the superconducting materials found to date are relatively delicate ceramics, making it difficult to use established techniques to draw extended lengths of superconducting wire. Much research has focussed on layer deposit techniques, applying a thin film of material onto a stable substrate, but this is currently only suitable for small-scale electrical circuits.
  • Infrastructure - Until room-temperature superconductors are found, the 100 mile loop of wire would have to be contained within a vacuum flask of liquid nitrogen. This in turn would require stable support, most commonly envisioned by burying the installation.
  • Critical Current - In general power systems look to maximize the current they are able to handle. This makes any losses due to inefficiencies in the system relatively insignificant. Unfortunately the superconducting properties of most materials break down as current increases, at a level known as the critical current. Current materials struggle, therefore, to carry sufficient current to make a commercial storage facility economically viable.
  • Critical Magnetic Field - Related to critical current, there is a similar limitation to superconductivity linked to the magnetic field induced in the wire, and this too is a factor at commercial storage levels


6. Next Steps
  • New materials and chemical processes are needed to improve their charge storage capabilities by increasing both their energy and their power densities. Incremental changes in existing technologies will not produce the breakthroughs needed to realize these improvements. Rather, a fundamental understanding of the physical and chemical processes that take place in the EC—including the electrodes, the electrolytes, and especially their interfaces—is needed to design revolutionary concepts.
  • The Engineering Test Model is a large SMES with a capacity of approximately 20 MW•h, capable of providing 400 MW of power for 100 seconds or 10 MW of power for 2 hours.


7. Companies
  • American Superconductor (NASDAQ: AMSC)- Devens, MA - AMSC’s D-VAR system is ideally suited to help meet wind farm interconnection standards. The D-VAR system is a fully integrated, inverter-based reactive compensation system (STATCOM). It can be seamlessly integrated with low cost capacitor banks in an extremely cost-effective solution that provides steady-state voltage regulation, power factor correction, and high and low voltage ride through capability for the entire wind farm. The D-VAR system can also “soft-switch” capacitors, thereby eliminating the voltage step changes seen by the wind farm and the utility.

  • ACCEL Instruments GmbH, Cologne, Germany - With its many years experience in design, manufacturing and testing ACCEL serves the increasing demand for superconducting accelerators world-wide. For production of the cavities either solid Niobium is used (bulk Nb cavities) or the technology of coating Nb-films on copper cavities is used (Nb/Cu sputter technology developed by CERN).

  • Bruker - EST - (Nasdaq: BRKR) Billerica, MA - Magnets and magnet systems are manufactured for special applications according to the customer's specification and needs including superconducting solenoids for Megajoule applications for energy storage (SMES)


8. Links

Flywheel

The most powerful flywheel energy storage systems currently for sale on the market can hold up to 133 kWh of energy


Navigate this Report
Back to Energy Storage Index
1. Background

2. Acronyms/Definitions
3. Business Case
4. Benefits
5. Risks/Issues
6. Case Studies
7. Companies
8. Links

1.Background
  • Flywheels are 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 producing electricity. Electricity is stored as the kinetic energy of the disc. Friction must be kept to a minimum to prolong the storage time. This is often achieved by placing the flywheel in a vacuum and using magnetic bearings, tending to make the method expensive. Larger flywheel speeds allow greater storage capacity but require strong materials such as composite materials to resist the centrifugal forces.

  • The flywheel provides power during period between the loss of utility supplied power and either the return of utility power or the start of a sufficient back-up power system (i.e., diesel generator). Flywheels provide 30 seconds of ride-through time, and back-up generators are typically online within 5-20 seconds.

  • Traditional flywheel rotors are usually constructed of steel and are limited to a spin rate of a few thousand RPM. Advanced flywheels constructed from carbon fiber materials and magnetic bearings can spin in vacuum at speeds up to 40,000 to 60,000 RPM.


2. Acronyms/Definitions
  1. Angular Instability - A low-frequency (usually less than 1 Hz) undamped power fluctuation traveling from one end of a power grid to the other end. This traveling wave cannot be easily damped and can take up significant capacity on transmission lines.
  2. Energy Recycling - The ability to use braking power from one train to move another or capture energy generated in a shipyard crane’s lowering cycle to lift the next container.
  3. Frequency Regulation - Electric frequency must be maintained very close to 60 hertz (Hz), or cycles per second (50 Hz in Europe and elsewhere). When the supply of electricity exactly matches the demand (or "load"), grid frequency is held at a stable level. Grid operators, therefore, seek to continuously balance electricity supply with load to maintain the proper frequency. They do this by directing about one percent of total generation capacity to increase or decrease its power output in response to frequency deviations.
  4. RPM – Revolutions per Minute
  5. UPS – Uninterruptible Power Supply


Beacon's Smart Energy 25flywheel's rotor assembly is sealed in a vacuum chamber and spins between 8,000 and 16,000 rpm. At 16,000 rpm, the surface speed of the rim would be approximately Mach 2 - or about 1500 mph - if it were operated in normal atmosphere so the rim must be enclosed in a high vacuum to reduce friction and energy losses. To reduce losses even further, the rotor is levitated with a combination of permanent magnets and an electromagnetic bearing. (Beacon filed for bankruptcy on October 30, 2011)



3. Business Case
  • Flywheel-based energy storage systems, unlike fossil-fuel power plants that are used on the grid for frequency regulation, are sustainable "green" technology solutions that consume no fossil fuel, nor produce CO2 or other emissions during operation.
  • Additional Regulation is required for 33% Renewable Portfolio Goals
  • Economics of 10MW Flywheel
    1. Capital $3360 – 3920 per kW
    2. Variable $1340 - 1570 per KWh
    3. Hours 0.25
    4. Total Cost $3695 - 4313 per kW
      $kW + (Hours x $/kWh)


4. Benefits
  • Frequency Regulation – Flywheels are designed to smooth out transient fluctuations in load and supply, Changing power output causes greater wear and tear on equipment, and fossil generators that perform frequency regulation incur higher operating costs due to increased fuel consumption and maintenance costs. They also suffer a significant loss in "heat rate" efficiency and produce greater quantities of CO2 and other unwanted emissions when throttling up and down to perform frequency regulation services.

  • UPS Protection - Flywheel storage is also currently used to provide UPS systems (such as those in large datacenters) for ride-through power necessary during transfer - that is, the relatively brief amount of time between a loss of power to the mains and the warm-up of an alternate source, such as a diesel generator. As a replacement for battery-based UPS systems, flywheel technology has the advantage of being virtually maintenance-free compared to maintenance-intensive and less-reliable battery-based UPS.

  • Angular Instability Control - If the low-frequency oscillation could be damped, the transmission line capacity could be restored making it easier to relieve congested lines or reduce possible grid instability. In the past, this type of instability has been linked to wide-scale regional blackouts costing billions of dollars in lost productivity, goods and services. A flywheel energy storage system, combined with phasor measurements and an integrated communications and control network, has the potential to overcome this vulnerability and prevent such blackouts.

  • Railway Voltage Control – As the spacing between trains decreases, rail systems become more prone to voltage drops that impair performance and reliability. While substations can be upgraded to add power conditioning equipment, space constraints and the related difficulty of increasing local power distribution can make it very costly to upgrade some substations. Flywheels can boost voltage when necessary.

  • Very High Burst of Power - Applications that require very high bursts of power for very short durations use flywheel power. Examples include Tokamak and laser experiments where a motor generator is spun up to operating speed and may actually come to a stop in one revolution.

  • VAR Support - Reactive power support can be provided on either a unitary or small-system basis, or as a secondary overlay application for a full-scale 20 MW frequency regulation power plant. For industrial and commercial end users, potential benefits include lower fees from utilities resulting from improvement of power factor levels that would otherwise fall below specified minimums, as well as higher power quality for sensitive industrial and commercial applications. For grid operators or utilities, potential benefits include the ability to defer investments in transmission and/or distribution infrastructure.

  • Adaptabilty - Compared to sustainable energy storage solutions such as molten salt, flywheels may also be more portable and site-adaptable. They are also highly durable and they are already starting to pop up in some high stress environments.



5. Risks/Issues
  • Scale – A flywheel generally only provides 15-30 minutes of duration. The ranges of power and energy storage technically and economically achievable tend to make flywheels unsuitable for general power system application.
  • Cost - Price is a legitimate concern –but performance characteristics and emission benefits provide compelling motivations for particular applications.


6. Case Studies

  • Flywheel technology has been implemented by EDA in the Azores on the islands of Graciosa and Flores. This system uses a 18MWs flywheel to improve power quality and thus allow increased renewable energy usage.

  • Powercorp in Australia have been developing applications using wind turbines, flywheels and low load diesel (LLD) technology to maximize the wind input to small grids. A system installed in Coral Bay, Western Australia, uses wind turbines coupled with a flywheel based control system and LLDs to achieve better than 60% wind contribution to the town grid.

  • Vycon has created a flywheel application it calls "energy recycling" that captures the energy contained in cargo containers being lowered by cranes and feeds it back to the crane for the next hoist.

    Cranes need large amounts of power in rapid bursts in quick succession for several hours a day. A single hoist might require 160 kilowatts to 300 kilowatts, take about 30 seconds, and get repeated every five minutes.

    Although cranes now mostly run on AC motors, they aren't grid connected. . The constant movement (and gigantic power requirements) wouldn't allow that. As a result, cranes derive their power from polluting diesel generators. And because cargo loads vary in size, port operators have to install generators for the worse case scenarios, leading to more fuel consumption and emissions that are warranted in most circumstances. Some of the generators are capable of generating 500 kilowatts to 800 kilowatts.

    Besides needing power for the lift, cranes burn diesel when lowering cargo to control the descent. On the drop, the AC motor is run in reverse, generating 200 kilowatts of power.  In a Toyota Prius, that generates power for the battery. On a cargo crane, the power is burned off as waste heat.
    The white box between the center wheels of this container crane is Vycon's flywheel

     In Vycon's system, the energy is absorbed into the rotating mass of the flywheel, which stores the energy and feeds it back into the system. The fuel saving largely come in through the fact that port operators can employ smaller generators once they have a flywheel.

    Vycon sells both a retrofit kit (take it away for $120,000) and a kit for new cranes. One of the key selling points is the rapid installation. Diesel generators regularly undergo scheduled maintenance; an overhaul can take a few weeks. Vycon goes in and offers a complete new system-generator and flywheel-that can be popped on to the crane in three days.

    The flywheel also lasts 20 years, which Romo says is probably longer than battery-only systems.



7. Companies
  1. Active Power (NASDAQ: ACPW) Austin TX - Provides the most energy-efficient critical power solutions and UPS systems in the world. Their flywheel-based solutions ensure business continuity in the event of power disturbances.

  2. Amber Kinetics, Fremont, CA - Won a $4 million Smart Grid Demonstration Project funding from DOE to develop and demonstrate an innovative flywheel technology for use in grid-connected, low-cost bulk energy storage applications. This demonstration effort, which partners with Lawrence Livermore National Laboratory, will improve on traditional flywheel systems, resulting in higher efficiency and cost reductions that will be competitive with pumped hydro technologies. Total project value is $10 million.

  3. Beacon Power (NASDAQ: BCON) Tyngsboro, MA - Spun off of SatCon Technology Corp in 1997 and went public in 2000.  Makes 2 and 6 kilowatt-hour flywheel (kinetic-electric) energy storage units. Beacon started out applying their technology to the telecom market but soon moved into the frequency regulation sector of the utility energy market. Beacon estimates the frequency regulation market as well in excess of $500 million and about one percent of load. Although Beacon designs and manufactures the flywheel storage systems, the firm now utilizes its flywheels in its new role as an Independent regulation services provider (IRSP).

    In 2009, Beacon Power received a $43 million DOE loan guarantee that was used to complete a 20 MW flywheel energy storage project in New York now in operation.

    In August 2011, Beacon was awarded a $5-million state grant toward construction of a 20-megawatt flywheel energy storage plant in Hazle Township, Pennsylvania. In addition to the $5 million state grant, the $53-million Hazle Township plant was also awarded a $24-million Smart Grid stimulus grant from the U.S. Department of Energy.

    On October 30, 2011, Beacon filed for bankruptcy just a year after the energy storage company received a $43 million loan guarantee from a controversial Department of Energy program.Beacon Power drew down $39 million of its government-guaranteed loan to fund a portion of a $69 million, 20-megawatt flywheel energy storage plant in Stephentown, New York.
    There are several key differences between Beacon's loan and Solyndra's (See my blog article Solyndra Failure), an Energy Department spokesman said on Sunday, noting the Beacon plant continues to operate, unlike Solyndra, which shut down shortly before filing for bankruptcy.

    The Energy Department also had agreed to restructure Solyndra's debt in a last-ditch effort to keep the company alive, a deal which put taxpayers behind $75 million in private investment. But for the Beacon project, the government loan is the first debt the company must pay, the spokesman said.  The loan guarantee for the project included "many protections for the taxpayer," said DOE spokesman Damien LaVera, noting the department is not directly exposed to Beacon's liabilities, has the operating plant as collateral, as well as cash reserves held by the business.

    It said in documents filed with Delaware's bankruptcy court that it had $72 million in assets and $47 million in debts.  Beacon currently operates at a loss and its revenues are not enough to support its operations, it said in court documents.  It blamed the bankruptcy on its inability to secure additional investments due to the financing terms mandated by the Department of Energy, its recent delisting by the Nasdaq stock market and the current "political climate."


  4. Power-Thru - Livonia, MI - Designs, manufactures and markets advanced flywheel energy storage systems that provide ride-through power and voltage stabilization for power quality and power recycling applications. Pentadyne is the world's leading manufacturer of flywheel energy storage systems.

  5. Vycon Yorba Linda CA - Serves the UPS industry. Vycon’s proprietary system consists of a steel hub with magnetic bearings, a dual motor/generator (the motor charges the system, the generator dispenses the energy), high tech system controls, and a converter that transforms the flywheel’s AC power into DC.

    In January 2010, Vycon closed a $13.7 million round of funding, which includes conversion of $6.5 million in existing convertible notes and $1.1 million of existing trade debt.



8. Links

Supply Shifting

Generation Domain - The National Institute of Standards and Technology released a common semantic model for the Smart Grid in June 2009 - NIST worked with standards development organizations to form a common representation of information models for the smart grid

Back to Smart Energy

(New).  Heat Pumps
FRIDAY, september 20, 2013
While heat pumps are not a traditional supply shifting technology, they can replace burning natural gas with efficient electric power and they do shift heat in the desired direction.

A. Natural Gas Fracking 
monday, december 1, 2014
Hydraulic fracturing has driven down the price of natural gas from a high of $13 per million British Thermal Units (mmBTU) in 2008, natural gas prices have plummeted to below $2.50 per mmBTU, nearing record-setting lows, a game changer for both coal and renewables.  Is the process worth the risk?



B. Managing Variable Energy Resources (VER)
monday, may 14, 2012
Smart Grid technology will enable intermittent resources such as wind and solar to participate by providing visibility of renewable production and capacity


C. Distributed Energy Resources (DER)
saturday, may 19, 2012
According to Amory Levins of the Rocky Mountain Institute, all new central thermal power stations are now obsolete and uncompetitive. What will a larger number of smaller-distributed power plants mean for the Smart Grid?


D. Hydroelectric Uprating
monday, september 23, 2013
Retrofitting dams to provide more generation at peak times is one of the most immediate, cost-effective, and environmentally acceptable means of developing additional electric power.

Pumped Hydro

To date, the only significant bulk electricity storage technology that is common in the market



Navigate this Page
Back to Energy Storage Index
1. Background

2. Acronyms/Definitions
3. Business Case
4. Benefits
5. Risks/Issues
6. Next Steps
7. Companies
8. Links



1.Background
  • Pumped storage hydroelectric power generation is used by some power plants for load balancing. The method stores energy in the form of water, pumped from a lower elevation reservoir to a higher elevation. Low-cost off-peak electric power is used to run the pumps. During periods of high electrical demand, the stored water is released through turbines. Although the losses of the pumping process makes the plant a net consumer of energy overall, the system increases revenue by selling more electricity during periods of peak demand, when electricity prices are highest. Pumped storage is the largest-capacity form of grid energy storage now available.
  • In the 1930s reversible hydroelectric turbines became available. These turbines could operate as both turbine-generators and in reverse as electric motor driven pumps. The latest in large-scale engineering technology are variable speed machines for greater efficiency. These machines generate in synchronization with the network frequency, but operate asynchronously, independent of the network frequency as motor-pumps.
  • During a 30-year period from the late 1950s to the late 1980s, approximately 19,500 MW of pumped hydroelectric storage facilities were brought into service in the United States. By 2000 the United States had 19.5 GW of pumped storage generating capacity, accounting for 2.5% of base load generating capacity. PHS generated (net) -5500 GWh of energy because more energy is consumed in pumping than is generated; losses occur due to water evaporation, electric turbine/pump efficiency, and friction.


2. Acronyms/Definitions
  • Conventional Hydroelectric Plants do not use pumped-storage, but those that have significant storage capacity may be able to play a similar role in the electrical grid as pumped storage, by deferring output until needed.

  • Hold Back Hydro - The need for expensive peaker power plants could be reduced, simply by holding back hydro reserves (water) for times when the most expensive peaker operation is now required. As renewables develop this could go further to act similarly to store power, not by actually pumping, but simply by gating off the water flow when renewable power was surging. This has the same effect as storage, since there is water held in reserve just as if it had been pumped there. Full capability would involve some addition of holding ponds to manage water flow appropriately.

    Spain seems to do this to some degree, meaning they completely shut off hydro output at night, thus having capacity to respond at peak times. It is not clear to what extent they utilize the rapid response possibilities.

  • Pumped Hydro in California
    1. Castaic Dam (1978), 1,566 MW
    2. Edward C. Hyatt (1968), 780 MW
    3. Helms (1984), 1,200 MW
    4. Iowa Hill, (Proposed 2010), 400 MW
    5. John S. Eastwood (1988), 200 MW
    6. Pyramid Lake (1973), 1,495 MW
    7. San Luis Dam (William R. Gianelli) (1968), 424 MW


3. Business Case
  • Linking windpower and hydropower can add to the nation’s supply of electrical energy. Large wind machines can be tied to existing hydroelectric power plants. Wind power can be used, when the wind is blowing, to reduce demands on hydropower. That would allow dams to save their water for later release to generate power in peak periods.
  • Pumped Hydro Economics (Conventional 1000 MW)
    1. Capital $1300 per kW
    2. Variable $80 per KWh
    3. Hours 10
    4. Total Cost $2100 per kW
      $kW + (Hours x $/kWh)


4. Benefits
  • Very Dispatchable – Hydroelectric generating units are able to start up quickly and make rapid adjustments in output. They operate efficiently when used for one hour or several hours. Thermal plants are much less able to respond to sudden changes in electrical demand, potentially causing frequency and voltage instability. Pumped storage plants can respond to load changes within seconds.
  • Relatively Efficient - Approximately 70% to 85% of the electrical energy used to pump the water into the elevated reservoir can be regained. The technique is currently the most cost-effective means of storing large amounts of electrical energy on an operating basis.
  • Supports Reliability - load following, and frequency control helps protect against system failures that could lead to the damage of equipment and even brown or blackouts.
  • Low Lifecycle Costs
  • Improved Response Time - The variable pump/turbines made today for pumped hydro can address numerous ancillary service needs; not only are they much more versatile when coupled with state of the art stators and electronics they being response times down to where a 15 minute two way market is possible. They are just now starting to replace the older models in some of the PHS facilities in the US in response to market demands for something other than peak energy.


5. Risks/Issues
  • Low Energy Density - Pumped storage systems requires either a very large body of water or a large variation in height. For example, 1000 kilograms of water (1 cubic meter) at the top of a 100 meter tower has a potential energy of about 0.272 kWh. The only way to store a significant amount of energy is by having a large body of water located on a hill relatively near, but as high as possible above, a second body of water. In some places this occurs naturally, in others one or both bodies of water have been man-made.
  • Geographic Limitations - make it difficult to be placed where needed most needed. Because of the need for significant elevation changes in pumped hydroelectric plan designs, the number of environmentally acceptable sites for future pumped hydroelectric facilities is very limited. The siting of new plants will face the same objections that the siting of new transmission lines faces today.
  • Evaporation - Losses from the exposed water surface.
  • Ecological Damage from fluctuating water levels. In the Pacific Northwest for example, incorporating wind power raises environmental issues as the BPA tries to balance mandates from states for more renewable energy against a responsibility to protect migrating salmon. The Northwest’s wind turbine farms are geographically concentrated at the east end of the Columbia River Gorge. While the BPA has a concentration of transmission lines in that corridor to serve dams, the lines are already overtaxed. And when the wind blows, all of the wind farms start sending power to the grid at the same time. The federal hydro system is a great tool to integrate with wind because reservoirs are the only large-scale way to store energy and can quickly ramp up and down to balance intermittent supply and demand. However, the system has its limits, and when wind speeds jump or fall well beyond the levels forecast by wind farm operators, it can require the agency to operate with inadequate reserves or spill water in a way that is harmful to fish.
  • Large Initial Investment - Capital costs are relatively high with long construction periods up to 7 or 8 years
  • Too Slow for System Regulation - Reaction time up to 10 minutes
  • Seasonal unpredictability.
  • Transmission Congestion - These plants are generally located some distance from load centers and can do little to effect potential congestion issues that impact utility transmission and distribution networks during periods of peak demand.


6. Next Steps
The Dutch government is exploring the creation of an “energy island,” whereby a hollowed-out artificial island in the North Sea would use pumped hydroelectric in reverse—windmills would pump water out of the island, and then hydroelectric turbines could generate electricity when it is desired from water flowing back into the island’s cavity

7. Companies
  • North American Hydro - Schofield, WI- Specializes in developing, upgrading, owning, and operating hydroelectric facilities. Unlike other companies, retaining assets in approximately 40 hydroelectric facilities allows us to offer integrated solutions that are backed by direct operations and maintenance experience.


8. Links

Energy Efficiency & Property Value

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